WorldWideScience

Sample records for based solder candidates

  1. Development of gold based solder candidates for flip chip assembly

    DEFF Research Database (Denmark)

    Chidambaram, Vivek; Hald, John; Hattel, Jesper Henri

    2009-01-01

    Flip chip technology is now rapidly replacing the traditional wire bonding interconnection technology in the first level packaging applications due to the miniaturization drive in the microelectronics industry. Flip chip assembly currently involves the use of high lead containing solders...... for interconnecting the chip to a carrier in certain applications due to the unique properties of lead. Despite of all the beneficial attributes of lead, its potential environmental impact when the products are discarded to land fills has resulted in various legislatives to eliminate lead from the electronic products...... based on its notorious legacy as a major health hazard across the spectrum of human generations and cultures. Flip chip assembly is also now increasingly being used for the high-performance (H-P) systems. These H-P systems perform mission-critical operations and are expected to experience virtually...

  2. Design of lead-free candidate alloys for high-temperature soldering based on the Au–Sn system

    DEFF Research Database (Denmark)

    Chidambaram, Vivek; Hattel, Jesper Henri; Hald, John

    2010-01-01

    Au–Sn based candidate alloys have been proposed as a substitute for high-lead content solders that are currently being used for high-temperature soldering. The changes in microstructure and microhardness associated with the alloying of Ag and Cu to the Au rich side as well to the Sn rich side of...... the Au–Sn binary system were explored in this work. Furthermore, the effects of thermal aging on the microstructure and microhardness of these promising Au–Sn based ternary alloys were investigated. For this purpose, the candidate alloys were aged at a lower temperature, 150°C for up to 1week and...

  3. Development of Au-Ge based candidate alloys as an alternative to high-lead content solders

    DEFF Research Database (Denmark)

    Chidambaram, Vivek; Hald, John; Hattel, Jesper Henri

    Au-Ge based candidate alloys have been proposed as an alternative to high-lead content solders that are currently being used for high-temperature applications. The changes in microstructure and microhardness associated with the addition of low melting point metals namely In, Sb and Sn to the Au......-Ge eutectic were investigated in this work. Furthermore, the effects of thermal aging on the microstructure and its corresponding microhardness of these promising candidate alloys have been extensively reported. To investigate the effects of aging temperature, candidate alloys were aged at a lower temperature...... induced by the In atoms were the most effective strengthening mechanism....

  4. Assessment of potential solder candidates for high temperature applications

    DEFF Research Database (Denmark)

    package with different solders of different melting temperatures. High Pb containing alloys where the lead levels can be above 85% by weight, is one of the solders currently being used in this technology. Responding to market pressure i.e. need for green electronic products there is now an increasing...... pressure to eliminate lead containing materials despite the fact that materials for high Pb containing alloys are currently not affected by any legislations. A tentative assessment was carried out to determine the potential solder candidates for high temperature applications based on the solidification...

  5. Au-Ge based Candidate Alloys for High-Temperature Lead-Free Solder Alternatives

    DEFF Research Database (Denmark)

    Chidambaram, Vivek; Hald, John; Hattel, Jesper Henri

    2009-01-01

    and microhardness has been extensively reported. Furthermore, the effects of thermal aging on the microstructure and its corresponding microhardness of these promising candidate alloys have been investigated in this work. After thermal aging at 200°C for different durations ranging from 1 day to 3 weeks...

  6. Solderability study of RABiTS-based YBCO coated conductors

    Energy Technology Data Exchange (ETDEWEB)

    Zhang Yifei [Oak Ridge National Laboratory, P.O. Box 2008, Oak Ridge, TN 37831-6305 (United States); Duckworth, Robert C., E-mail: duckworthrc@ornl.gov [Oak Ridge National Laboratory, P.O. Box 2008, Oak Ridge, TN 37831-6305 (United States); Ha, Tam T.; Gouge, Michael J. [Oak Ridge National Laboratory, P.O. Box 2008, Oak Ridge, TN 37831-6305 (United States)

    2011-08-15

    Study examines the implication of solder and flux selection in YBCO splice joints. Focus is on commercially available RABiTS-based YBCO coated conductors. Solderability varied with solder and flux for three different stabilizations tested. Resistivity of stabilizer was dominant factor in splice joint resistance. Solder materials affected splice joint resistance when solderability was poor. The solderability of commercially available YBa{sub 2}Cu{sub 3}O{sub 7-x} (YBCO) coated conductors that were made from Rolling Assisted Biaxially Textured Substrates (RABiTS)-based templates was studied. The coated conductors, also known as second-generation (2G) high temperature superconductor (HTS) wires (in the geometry of flat tapes about 4 mm wide), were laminated with copper, brass, or stainless steel strips as stabilizers. To understand the factors that influence their solderability, surface profilometry and scanning electron microscopy were used to characterize the wire surfaces. The solderability of three solders, 52In48Sn, 67Bi33In, and 100In (wt.%), was evaluated using a standard test (IPC/ECA J-STD-002) and with two different commercial fluxes. It was found that the solderability varied with the solder and flux but the three different wires showed similar solderability for a fixed combination of solder and flux. Solder joints of the 2G wires were fabricated using the tools and the procedures recommended by the HTS wire manufacturer. The solder joints were made in a lap-joint geometry and with the superconducting sides of the two wires face-to-face. The electrical resistances of the solder joints were measured at 77 K, and the results were analyzed to qualify the soldering materials and evaluate the soldering process. It was concluded that although the selection of soldering materials affected the resistance of a solder joint, the resistivity of the stabilizer was the dominant factor.

  7. The Effect of Gap Angle on Tensile Strength of Preceramic Base Metal Solder Joints

    OpenAIRE

    Farnaz Fattahi; Zahra Hashemi Ardakani; Maryam Hashemi Ardakani

    2015-01-01

    Statement of the Problem: Soldering is a process commonly used in fabricating dental prosthesis. Since most soldered prosthesis fail at the solder joints; the joint strength is of utmost importance. Purpose: The purpose of this study was to evaluate the effect of gap angle on the tensile strength of base metal solder joints. Materials and Method: A total number of 40 Ni-Cr samples were fabricated according to ADA/ISO 9693 specifications for tensile test. Samples were cut at the midpoint...

  8. Nano copper based high temperature solder alternative

    Science.gov (United States)

    Sharma, Akshay

    Nano Cu an alternative to high temperature solder is developed by the Advance Technological Center at the Lockheed Martin Corporation. A printable paste of Cu nano particles is developed with an ability to fuse at 200°C in reflow oven. After reflow the deposited material has nano crystalline and nano porous structure which affects its properties. Accelerated test are performed on nano Cu deposition having nano porous and nano crystalline structure for assessment and prediction of reliability. Nano Cu assemblies with different bond layer thickness are sheared to calculate the strength of the material and are correlated with the porous and crystalline structure of nano Cu. Thermal and isothermal fatigue test are performed on nano Cu to see the dependency of life on stress and further surface of failed assemblies were observed to determine the type of failure. Creep test at RT are performed to find the type of creep mechanism and how they are affected when subjected to high temperature. TEM, SEM, X-ray, C-SAM and optical microscopy is done on the nano Cu sample for structure and surface analysis.

  9. Research on defects inspection of solder balls based on eddy current pulsed thermography.

    Science.gov (United States)

    Zhou, Xiuyun; Zhou, Jinlong; Tian, Guiyun; Wang, Yizhe

    2015-01-01

    In order to solve tiny defect detection for solder balls in high-density flip-chip, this paper proposed feasibility study on the effect of detectability as well as classification based on eddy current pulsed thermography (ECPT). Specifically, numerical analysis of 3D finite element inductive heat model is generated to investigate disturbance on the temperature field for different kind of defects such as cracks, voids, etc. The temperature variation between defective and non-defective solder balls is monitored for defects identification and classification. Finally, experimental study is carried on the diameter 1mm tiny solder balls by using ECPT and verify the efficacy of the technique. PMID:26473871

  10. Fast formation and growth of high-density Sn whiskers in Mg/Sn-based solder/Mg joints by ultrasonic-assisted soldering: Phenomena, mechanism and prevention.

    Science.gov (United States)

    Li, M Y; Yang, H F; Zhang, Z H; Gu, J H; Yang, S H

    2016-01-01

    A universally applicable method for promoting the fast formation and growth of high-density Sn whiskers on solders was developed by fabricating Mg/Sn-based solder/Mg joints using ultrasonic-assisted soldering at 250 °C for 6 s and then subjected to thermal aging at 25 °C for 7 d. The results showed that the use of the ultrasonic-assisted soldering could produce the supersaturated dissolution of Mg in the liquid Sn and lead to the existence of two forms of Mg in Sn after solidification. Moreover, the formation and growth of the high-density whiskers were facilitated by the specific contributions of both of the Mg forms in the solid Sn. Specifically, interstitial Mg can provide the persistent driving force for Sn whisker growth, whereas the Mg2Sn phase can increase the formation probability of Sn whiskers. In addition, we presented that the formation and growth of Sn whiskers in the Sn-based solders can be significantly restricted by a small amount of Zn addition (≥3 wt.%), and the prevention mechanisms are attributed to the segregation of Zn atoms at grain or phase boundaries and the formation of the lamellar-type Zn-rich structures in the solder. PMID:27273421

  11. Fast formation and growth of high-density Sn whiskers in Mg/Sn-based solder/Mg joints by ultrasonic-assisted soldering: Phenomena, mechanism and prevention

    Science.gov (United States)

    Li, M. Y.; Yang, H. F.; Zhang, Z. H.; Gu, J. H.; Yang, S. H.

    2016-06-01

    A universally applicable method for promoting the fast formation and growth of high-density Sn whiskers on solders was developed by fabricating Mg/Sn-based solder/Mg joints using ultrasonic-assisted soldering at 250 °C for 6 s and then subjected to thermal aging at 25 °C for 7 d. The results showed that the use of the ultrasonic-assisted soldering could produce the supersaturated dissolution of Mg in the liquid Sn and lead to the existence of two forms of Mg in Sn after solidification. Moreover, the formation and growth of the high-density whiskers were facilitated by the specific contributions of both of the Mg forms in the solid Sn. Specifically, interstitial Mg can provide the persistent driving force for Sn whisker growth, whereas the Mg2Sn phase can increase the formation probability of Sn whiskers. In addition, we presented that the formation and growth of Sn whiskers in the Sn-based solders can be significantly restricted by a small amount of Zn addition (≥3 wt.%), and the prevention mechanisms are attributed to the segregation of Zn atoms at grain or phase boundaries and the formation of the lamellar-type Zn-rich structures in the solder.

  12. Effect of grain orientation on mechanical properties and thermomechanical response of Sn-based solder interconnects

    International Nuclear Information System (INIS)

    The thermomechanical response of Sn-based solder interconnects with differently oriented grains was investigated by electron backscattered diffraction technique under thermal cycling and thermal shock testing in this study. The results showed that deformation and cracking of solder interconnects have a close relationship with the unique characteristics of grain orientation and boundaries in each solder interconnect, and deformation was frequently confined within the high-angle grain boundaries. The micro Vickers hardness testing results showed that the hardness varied significantly depending on the grain orientation and structure, and deformation twins can be induced around the indents by the indentation testing. - Highlights: • Thermomechanical response shows a close relationship with the grain structure. • Deformation was frequently confined within the high-angle grain boundaries. • Different grain orientations exhibit different hardness. • Deformation twins can be induced around the indents in SAC105 solder interconnects

  13. Mechanical property of the epoxy-contained Sn–58Bi solder with OSP surface finish

    Energy Technology Data Exchange (ETDEWEB)

    Myung, Woo-Ram [SKKU Advanced Institute of Nanotechnology (SAINT), Sungkyunkwan University, 300 Cheoncheon-dong, Jangan-gu, Suwon 440-746 (Korea, Republic of); Kim, Yongil [Micro Electronic Packaging Laboratory, Sungkyunkwan University, 300 Cheoncheon-dong, Jangan-gu, Suwon 440-746 (Korea, Republic of); Jung, Seung-Boo, E-mail: sbjung@skku.edu [School of Advanced Materials Science and Engineering, Sungkyunkwan University, 300 Cheoncheon-dong, Jangan-gu, Suwon 440-746 (Korea, Republic of)

    2014-12-05

    Highlights: • We studied the improved bonding properties of the Sn–58Bi epoxy solder. • We evaluated the mechanical properties compared no surface finished and OSP surface finished on the Cu substrate. • The Sn–58Bi solder with epoxy exhibited the higher value of shear strength than that of Sn–58Bi solder. • The epoxy solder of OSP finished sample showed higher number of drops than other conditions. - Abstract: In the electronic packaging technology, lead-free solders have been widely used to replace lead-based solders because of the toxicity of lead. Among the investigated lead-free solders, the Sn–58Bi solder has been considered as a highly promising candidate because of its low-melting temperature, high tensile strength and good creep resistance. However, the Sn–58Bi solder has poor ductility and shock absorbance. To enhance the mechanical properties of the Sn–58Bi solder, epoxy resin is mixed with the Sn–58Bi solder. The advantages of the Sn–58Bi solder with epoxy are good reliability and no need of a cleaning process. This study elucidated not only the mechanical properties of the Sn–58Bi epoxy solder but also the effects of the epoxy during the reflow process by conducting a shear test and a board-level drop test. The shear strength of the Sn–58Bi epoxy solder was about 2 times higher than that of the Sn–58Bi solder. In result of the drop test, the Sn–58Bi solder specimen failed under the 10th drop. However, the number of drops of the Sn–58Bi epoxy solder was over 100 drops without failure.

  14. Mechanical property of the epoxy-contained Sn–58Bi solder with OSP surface finish

    International Nuclear Information System (INIS)

    Highlights: • We studied the improved bonding properties of the Sn–58Bi epoxy solder. • We evaluated the mechanical properties compared no surface finished and OSP surface finished on the Cu substrate. • The Sn–58Bi solder with epoxy exhibited the higher value of shear strength than that of Sn–58Bi solder. • The epoxy solder of OSP finished sample showed higher number of drops than other conditions. - Abstract: In the electronic packaging technology, lead-free solders have been widely used to replace lead-based solders because of the toxicity of lead. Among the investigated lead-free solders, the Sn–58Bi solder has been considered as a highly promising candidate because of its low-melting temperature, high tensile strength and good creep resistance. However, the Sn–58Bi solder has poor ductility and shock absorbance. To enhance the mechanical properties of the Sn–58Bi solder, epoxy resin is mixed with the Sn–58Bi solder. The advantages of the Sn–58Bi solder with epoxy are good reliability and no need of a cleaning process. This study elucidated not only the mechanical properties of the Sn–58Bi epoxy solder but also the effects of the epoxy during the reflow process by conducting a shear test and a board-level drop test. The shear strength of the Sn–58Bi epoxy solder was about 2 times higher than that of the Sn–58Bi solder. In result of the drop test, the Sn–58Bi solder specimen failed under the 10th drop. However, the number of drops of the Sn–58Bi epoxy solder was over 100 drops without failure

  15. Soldering of aluminium alloys

    International Nuclear Information System (INIS)

    A literature survey about soldering in general and aluminium alloys soldering in particular is presented. The existing methods of soldering aluminium alloys are described. These include soldering with flux, soldering after preliminary plating, vacuum brazipressure and temperature (NTP), sample age calculation based on 14C half life of 5570 and 5730 years, age correction for NTP, dendrochronological corrections and the relative radiocarbon concentration. All results are given with one standard deviation. Input data test (Chauvenet's criterion), gas purity test, standard deviation test and test of the data processor are also included in the program. (author)

  16. Effects of Ga Addition on Interfacial Reactions Between Sn-Based Solders and Ni

    Science.gov (United States)

    Wang, Chao-Hong; Li, Kuan-Ting

    2016-07-01

    The use of Ga as a micro-alloying element in Sn-based solders can change the microstructure of solder joints to improve the mechanical properties, and even suppress the interfacial intermetallic compound (IMC) growth. This research investigated the effects of Ga addition (0.2-1 wt.%Ga) on the IMC formation and morphological evolution in the Sn-based solder joints with Ni substrate. In the soldering reaction at 250°C and with less than 0.2 wt.%Ga addition, the formed phase was Ni3Sn4. When the Ga addition increased to 0.5 wt.%, it changed to a thin Ni2Ga3 layer of ˜1 μm thick, which stably existed at the interface in the initial 1-h reaction. Subsequently, the whole Ni2Ga3 layer detached from the Ni substrate and drifted into the molten solder. The Ni3Sn4 phase became dominant in the later stage. Notably, the Ga addition significantly reduced the grain size of Ni3Sn4, resulting in the massive spalling of Ni3Sn4 grains. With 1 wt.%Ga addition, the Ni2Ga3 layer remained very thin with no significant growth, and it stably existed at the interface for more than 10 h. In addition, the solid-state reactions were examined at temperatures of 160°C to 200°C. With addition of 0.5 wt.%Ga, the Ni3Sn4 phase dominated the whole reaction. By contrast, with increasing to 1 wt.%Ga, only a thin Ni2Ga3 layer was found even after aging at 160°C for more than 1200 h. The 1 wt.%Ga addition in solder can effectively inhibit the Ni3Sn4 formation in soldering and the long-term aging process.

  17. Research and application of visual location technology for solder paste printing based on machine vision

    Institute of Scientific and Technical Information of China (English)

    Luosi WEI; Zongxia JIAO

    2009-01-01

    A location system is very important for solder paste printing in the process of surface mount technology (SMT). Using machine vision technology to complete the location mission is new and very efficient. This paper presents an integrated visual location system for solder paste printing based on machine vision. The working principle of solder paste printing is introduced and then the design and implementation of the visual location system are described. In the system, two key techniques are completed by secondary development based on VisionPro.One is accurate image location solved by the pattern-based location algorithms of PatMax. The other one is camera calibration that is achieved by image warping technology through the checkerboard plate. Moreover, the system can provide good performances such as high image locating accuracy with 1/40 sub-pixels, high anti-jamming, and high-speed location of objects whose appearance is rotated, scaled, and/or stretched.

  18. Soldering handbook

    CERN Document Server

    Vianco, Paul T

    1999-01-01

    Contains information related to soldering processes, and solder joint performance and reliability. Covers soldering fundamentals, technology, materials, substrate materials, fluxes, pastes, assembly processes, inspection, and environment. Covers today's advanced joining applications and emphasizes new materials, including higher strength alloys; predictive performance; computer modeling; advanced inspection techniques; new processing concepts, including laser heating; and the resurgence in ultrasonic soldering.

  19. The Effect of Gap Angle on Tensile Strength of Preceramic Base Metal Solder Joints

    Directory of Open Access Journals (Sweden)

    Farnaz Fattahi

    2015-12-01

    Full Text Available Statement of the Problem: Soldering is a process commonly used in fabricating dental prosthesis. Since most soldered prosthesis fail at the solder joints; the joint strength is of utmost importance. Purpose: The purpose of this study was to evaluate the effect of gap angle on the tensile strength of base metal solder joints. Materials and Method: A total number of 40 Ni-Cr samples were fabricated according to ADA/ISO 9693 specifications for tensile test. Samples were cut at the midpoint of the bar, and were placed at the considered angles by employing an explicitly designed device. They were divided into 4 groups regarding the gap angle; Group C (control group with parallel gap on steady distance of 0.2mm, Group 1: 10°, Group 2: 20°, and Group3: 30° gap angles. When soldered, the specimens were all tested for tensile strength using a universal testing machine at a cross-head speed of 0.5 mm/min with a preload of 10N. Kruskal-Wallis H test was used to compare tensile strength among the groups (p< 0.05. Results: The mean tensile strength values obtained from the study groups were respectively 307.84, 391.50, 365.18, and 368.86 MPa. The tensile strength was not statistically different among the four groups in general (p≤ 0.490. Conclusion: Making the gap angular at the solder joints and the subsequent unsteady increase of the gap distance would not change the tensile strength of the joint.

  20. Study on solder joint reliability of ceramic ball grid array component based on design of experiment method

    Institute of Scientific and Technical Information of China (English)

    Wu Zhaohua; Huang Chunyue; Zhou Dejian

    2006-01-01

    Four process parameters, pad diameter, stencil thickness, ball diameter and stand-off were chosen as four control factors.By using an L25 ( 56 ) orthogonal array the ceramic ball grid array ( CBGA ) solder joints which have 25 different combinations of process parameters were designed.The numerical models of all the 25 CBGA solder joints were developed using the Surface Evolver.Utilizing the surface coordinate exported from the 25 CBGA solder joints numerical models, the finite element analysis models were set up and the nonlinear finite element analysis of the CBGA solder joints under thermal cycles were performed by ANSYS.The thermal fatigne life of CBGA solder joint was calculated using Coffin-Manson equation.Based on the calculated thermal fatigue life results, the range analysis and the variance analysis were performed.The results show that the fatigue life of CBGA solder joint is affected by the pad diameter, the stencil thickness, the ball diameter and the standoff in a descending order, the best combination of process parameters results in the longest fatigue life is 0.07 mm stand-off,0.125 mm stencil thickness of, 0.85 mm ball diameter and 0.89 mm pad diameter.With 95% confidence the pad diameter has a significant effect on the reliability of CBGA solder joints whereas the stand-off, the stencil thickness and the ball diameter have little effect on the reliability of CBGA solder joints.

  1. Low-strain laser-based solder joining of mounted lenses

    Science.gov (United States)

    Burkhardt, Thomas; Hornaff, Marcel; Kamm, Andreas; Burkhardt, Diana; Schmidt, Erik; Beckert, Erik; Eberhardt, Ramona; Tünnermann, Andreas

    2015-09-01

    A novel laser-based soldering technique - Solderjet Bumping - using liquid solder droplets in a flux-free process with only localized heating is presented. We demonstrate an all inorganic, adhesive free bonding of optical components and support structures suitable for optical assemblies and instruments under harsh environmental conditions. Low strain bonding suitable for a following high-precision adjustment turning process is presented, addressing components and subsystems for objectives for high power and short wavelengths. The discussed case study shows large aperture transmissive optics (diameter approx. 74 mm and 50 mm) made of fused silica and LAK9G15, a radiation resistant glass, bonded to thermally matched metallic mounts. The process chain of Solderjet Bumping - cleaning, solderable metallization, handling, bonding and inspection - is discussed. This multi-material approach requires numerical modelling for dimensioning according to thermal and mechanical loads. The findings of numerical modelling, process parametrization and environmental testing (thermal and vibrational loads) are presented. Stress and strain introduced into optical components as well as deformation of optical surfaces can significantly deteriorate the wave front of passing light and therefore reduce system performance significantly. The optical performance with respect to stress/strain and surface deformation during bonding and environmental testing were evaluated using noncontact and nondestructive optical techniques: polarimetry and interferometry, respectively. Stress induced surface deformation of less than 100 nm and changes in optical path difference below 5 nm were achieved. Bond strengths of about 55 MPa are reported using tin-silver-copper soft solder alloy.

  2. High-temperature lead-free solder alternatives

    DEFF Research Database (Denmark)

    Nachiappan, Vivek Chidambaram; Hattel, Jesper Henri; Hald, John

    2011-01-01

    For lead-free solders in the high-temperature regime, unfortunately, a limited number of alloying systems are available. These are Bi based alloys, gold involving alloys and Zn–Al based alloys. Based on these systems, possible candidate alloys were designed to have a melting range between 270°C and...... 350°C. Each has its own superior characteristics as well as some drawbacks however none of them can fulfill all the requirements to replace the current high-lead content solders. Even the alternative technologies that are currently being developed cannot address several critical issues of high......-temperature soldering. Therefore, further research and development of high-temperature lead-free soldering is obviously needed....

  3. High-temperature soldering of carborundum-based ceramics with TZM molybdenum alloy

    International Nuclear Information System (INIS)

    In the paper, properties of a modern composite material designed SiC30 silicon carbide based with a fraction of graphite and free silicon are presented. Due to such properties like high hardness, thermal shock, wear and chemical resistance, this material is applied for heavy-duty machine parts and high-temperature regime parts. However, the specific structure of this silicide ceramics makes additional difficulties in the process of bonding with metals. Subsequent phases of the experiment and its analysis are presented. As a result, satisfactory bonds of the SiC-C-Si ceramics with the TZM molybdenum-based high-temperature alloy were obtained. When choosing the copper based, high temperature solder with active components Cr, Zr and Ti, the wettability test played an immense role. To obtain a soldered joint, the wedge test was of most importance. This test permitted assessment of the existing physicochemical phenomena, choice of the gap width and its transfer to the parallel joint. This resulted in obtaining a soldered joint od advantageous structure with no cracks. Metallographic evaluation of the joints was based on optical and electron microscopy and on microhardness measurements. (author)

  4. Thermal analysis of selected tin-based lead-free solder alloys

    DEFF Research Database (Denmark)

    Palcut, Marián; Sopoušek, J.; Trnková, L.; Hodúlová, E.; Szewczyková, B.; Ožvold, M.; Turňa, M.; Janovec, J.

    2009-01-01

    The Sn-Ag-Cu alloys have favourable solderability and wetting properties and are, therefore, being considered as potential lead-free solder materials. In the present study, tin-based Sn-Ag-Cu and Sn-Ag-Cu-Bi alloys were studied in detail by a differential scanning calorimetry (DSC) and...... thermodynamic calculations using the CALPHAD approach. The amount of the alloying elements in the materials was chosen to be close to the respective eutectic composition and the nominal compositions were the following: Sn-3.7Ag-0.7Cu, Sn-1.0Ag-0.5Cu-1Bi (in wt.%). Thermal effects during melting and solidifying...... simulated using the Thermo-Calc software package. This approach enabled us to obtain the enthalpy of cooling for each alloy and to compare its temperature derivative with the experimental DSC curves....

  5. Effect of alloying elements on the creep behavior of high Pb-based solders

    International Nuclear Information System (INIS)

    Research highlights: → This study examines creep behavior of four high Pb-based solders with alloying elements. → Dislocation creep limited by dislocation climb or viscous solute drag occurs in high Pb solders. → Viscous solute drag is the rate-limiting step for creep of 90Pb-10Sn due to high concentration of Sn. → The climb mechanism is switched from pipe diffusion to lattice diffusion at ∼0.7Tm. → Activation energy for dislocation creep is reduced by In and Sn substitutional elements. - Abstract: This study examines the high temperature creep behavior of several Pb-based alloys. All compositions tested were found to follow power-law dislocation creep in the strain rate range of 10-9-10-3 s-1. Both the stress exponent and activation energy were measured from 298 to 473 K to identify the rate controlling mechanism for creep deformation. Creep of 95Pb-5In, 92.5Pb-5Sn-2.5Ag, 93Pb-3Sn-2Ag-2In was rate limited by dislocation climb from the observed stress exponent. A transition in the controlling climb mechanism from pipe diffusion to lattice diffusion was observed around 0.7Tm. Creep of 90Pb-10Sn was, however, rate limited by viscous solute drag rather than dislocation climb due to the greater concentration of Sn in Pb. The enhancement in self-diffusion of Pb was dependent on the degree of solid solution with solute atoms. The outcome of this work identifies variables related to the alloy elements that control creep behavior of Pb-based alloys used in high temperature applications where traditional solders cannot be used.

  6. Structural and mechanical characteristics of some lead-free Cu-Sn based solder alloys

    OpenAIRE

    Mitovski Aleksandra M.; Balanović Ljubiša T.; Živković Dragana T.; Marjanović Šaša R.; Marjanović Bata R.; Novaković Slađana O.

    2008-01-01

    The results of structural and mechanical characteristics of lead-free Cu-Sn based solder alloys, produced in Company "11. mart" AD Srebrenica (Republic of Srpska), are presented in this paper. The results of investigation of samples - alloys CuSnl4, CuSnlFelAlO.5, CuSnlOFelAllMnO.5 and CuA110Fe3Mn produced by different processing methods, include the data obtained by optical microscopy and measurements of hardness, micro hardness and electroconductivity, in order to characterize mentioned all...

  7. Transient liquid phase Ag-based solder technology for high-temperature packaging applications

    International Nuclear Information System (INIS)

    Highlights: • Ag-based transient-liquid-phase (TLP) bonding for high-temperature applications. • The shear strength measured at 250 °C showed good high temperature performance. • A higher amount of Sn content than the stoichiometric ratio needed for joining Cu UBM. • Ag–Sn TLP bonding is an effective interconnection method for harsh environment. -- Abstracts: A lead-free Ag-based soldering technique through transient-liquid-phase (TLP) bonding is proposed in this study for high-temperature microelectronic packaging applications. The solder paste, which contained Ag and Sn powders with a no-clean flux, was used to join Cu substrates. The setup was bonded at 250 °C for 10 minutes. The study focuses on mechanical and microstructural characterizations of the joints. The shear strength measured at 250 °C shows good high temperature performance of the joint. The effects of Ag and Sn contents on mechanical, electrical and thermal properties of sintered bulk Ag–Sn samples were also investigated independently. The results demonstrate that the Ag–Sn TLP bonding is an effective interconnection method for harsh environment electronic packaging

  8. Development of new multicomponent Sn–Ag–Cu–Bi lead-free solders for low-cost commercial electronic assembly

    International Nuclear Information System (INIS)

    Highlights: • Small amounts of Bi have been added into Sn–1.5Ag–0.7Cu solder. • Bi reduced the undercooling and eutectic temperature of SAC257 solder. • Bi refined the microstructure and diminishes the nucleation rate of IMCs. • Bi increased the creep resistance and fracture lifetime of the solder. • Overall SAC properties can be improved adding not more than 3 wt.% Bi. - Abstract: Eutectic Sn–Ag–Cu (SAC) solder is one of the candidate alternatives to Sn–Pb-based solder alloys. The coupling effect of both minor alloying Bi addition and reducing the amount of Ag phase have been proposed as an important approach to optimize existing and to develop new SAC solders. Characteristics of new Sn–Ag–Cu–Bi solders were analyzed and compared with those of as-solidified Sn–1.5Ag–0.7Cu (SAC157) alloy. The results of differential scanning calorimetry (DSC) indicate significant reduction of both undercooling, eutectic temperature, solidus and liquidus temperatures with the addition of Bi into SAC(157) solder, although the pasty range remains the same or slightly increased. Moreover, SAC(157) solders containing Bi were found to have a higher creep resistance (126.1 times) than SAC(157) solder at the same stress level and testing temperature. The higher creep resistance was contributed by the solid solution and precipitations strengthen effects of Bi. The precipitation of these Bi atoms or particles can significantly refine the microstructure, blocks the movement of dislocations and increases the creep resistance of Bi-containing solders. The creep life time of plain SAC(157) alloy was extremely enlarged 23.7 times with the addition of 3 wt.% Bi. Constitutive Garofalo model of creep for both SAC(157) and Sn–Ag–Cu–Bi solders was assembled based on the experimental data

  9. Development of new multicomponent Sn–Ag–Cu–Bi lead-free solders for low-cost commercial electronic assembly

    Energy Technology Data Exchange (ETDEWEB)

    El-Daly, A.A., E-mail: dreldaly11@yahoo.com [Physics Department, Faculty of Science, Zagazig Univ., Zagazig (Egypt); Center of Nanotechnology, Zagazig Univ., Zagazig (Egypt); El-Taher, A.M. [Physics Department, Faculty of Science, Zagazig Univ., Zagazig (Egypt); Center of Nanotechnology, Zagazig Univ., Zagazig (Egypt); Gouda, S. [Physics Department, Faculty of Science, Zagazig Univ., Zagazig (Egypt)

    2015-04-05

    Highlights: • Small amounts of Bi have been added into Sn–1.5Ag–0.7Cu solder. • Bi reduced the undercooling and eutectic temperature of SAC257 solder. • Bi refined the microstructure and diminishes the nucleation rate of IMCs. • Bi increased the creep resistance and fracture lifetime of the solder. • Overall SAC properties can be improved adding not more than 3 wt.% Bi. - Abstract: Eutectic Sn–Ag–Cu (SAC) solder is one of the candidate alternatives to Sn–Pb-based solder alloys. The coupling effect of both minor alloying Bi addition and reducing the amount of Ag phase have been proposed as an important approach to optimize existing and to develop new SAC solders. Characteristics of new Sn–Ag–Cu–Bi solders were analyzed and compared with those of as-solidified Sn–1.5Ag–0.7Cu (SAC157) alloy. The results of differential scanning calorimetry (DSC) indicate significant reduction of both undercooling, eutectic temperature, solidus and liquidus temperatures with the addition of Bi into SAC(157) solder, although the pasty range remains the same or slightly increased. Moreover, SAC(157) solders containing Bi were found to have a higher creep resistance (126.1 times) than SAC(157) solder at the same stress level and testing temperature. The higher creep resistance was contributed by the solid solution and precipitations strengthen effects of Bi. The precipitation of these Bi atoms or particles can significantly refine the microstructure, blocks the movement of dislocations and increases the creep resistance of Bi-containing solders. The creep life time of plain SAC(157) alloy was extremely enlarged 23.7 times with the addition of 3 wt.% Bi. Constitutive Garofalo model of creep for both SAC(157) and Sn–Ag–Cu–Bi solders was assembled based on the experimental data.

  10. Solder joint technology materials, properties, and reliability

    CERN Document Server

    Tu, King-Ning

    2007-01-01

    Solder joints are ubiquitous in electronic consumer products. The European Union has a directive to ban the use of Pb-based solders in these products on July 1st, 2006. There is an urgent need for an increase in the research and development of Pb-free solders in electronic manufacturing. For example, spontaneous Sn whisker growth and electromigration induced failure in solder joints are serious issues. These reliability issues are quite complicated due to the combined effect of electrical, mechanical, chemical, and thermal forces on solder joints. To improve solder joint reliability, the science of solder joint behavior under various driving forces must be understood. In this book, the advanced materials reliability issues related to copper-tin reaction and electromigration in solder joints are emphasized and methods to prevent these reliability problems are discussed.

  11. Solder joint reliability of indium-alloy interconnection

    Science.gov (United States)

    Shimizu, Kozo; Nakanishi, Teru; Karasawa, Kazuaki; Hashimoto, Kaoru; Niwa, Koichi

    1995-01-01

    Recent high-density very large scale integrated (VLSI) interconnections in multichip modules require high-reliability solder interconnection to enable us to achieve small interconnect size andlarge number of input/output terminals, and to minimize soft errors in VLSIs induced by α-particle emission from solder. Lead-free solders such as indium (In)-alloy solders are a possible alternative to conventional lead-tin (Pb-Sn) solders. To realize reliable interconnections using In-alloy solders, fatigue behavior, finite element method (FEM) simulations, and dissolution and reaction between solder and metallization were studied with flip-chip interconnection models. We measured the fatigue life of solder joints and the mechanical properties of solders, and compared the results with a computer simulation based on the FEM. Indium-alloy solders have better mechanical properties for solder joints, and their flip-chip interconnection models showed a longer fatigue life than that of Pb-Sn solder in thermal shock tests between liquid nitrogen and room temperatures. The fatigue characteristics obtained by experiment agree with that given by FEM analysis. Dissolution tests show that Pt film is resistant to dissolution into In solder, indicating that Pt is an adequate barrier layer material for In solder. This test also shows that Au dissolution into the In-Sn solder raises its melting point; however, Ag addition to In-Sn solder prevents melting point rise. Experimental results show that In-alloy solders are suitable for fabricating reliable interconnections.

  12. Research of Interaction Between Zn Based Solders and Cu, Al Substrates

    OpenAIRE

    Prach Michal; Kostolný Igor; Koleňák Roman

    2014-01-01

    The paper deals with the study of interaction between Cu, Al substrates (purity 5N) and ZnAl4, ZnAg6Al6 zinc solders for higher application temperatures. Soldering was performed with power ultrasound in the air without flux application at temperature 420 °C. Acting time of ultrasonic vibration was 3 s and ultrasound frequency was 40 kHz. Soldered joints were assessed by optical light microscopy and EDX microanalysis. Intermetallic layers (IM) CuZn4 and Cu5Zn8 were formed at the Cu/ZnAl4 bound...

  13. Soldering on

    Czech Academy of Sciences Publication Activity Database

    Watson, A.; Kroupa, Aleš; Ipser, H.; Dinsdale, A.; Vřešťál, J.

    2007-01-01

    Roč. 15, č. 7 (2007), s. 32-33. ISSN 0967-8638 Institutional research plan: CEZ:AV0Z20410507 Keywords : lead -ree solders * high temperatures Subject RIV: BJ - Thermodynamics Impact factor: 0.153, year: 2007

  14. Microstructurally based thermomechanical fatigue lifetime model of solder joints for electronic applications

    Energy Technology Data Exchange (ETDEWEB)

    Frear, D.R.; Rashid, M.M.; Burchett, S.N.

    1993-07-01

    We present a new methodology for predicting the fatigue life of solder joints for electronics applications. This approach involves integration of experimental and computational techniques. The first stage involves correlating the manufacturing and processing parameters with the starting microstructure of the solder joint. The second stage involves a series of experiments that characterize the evolution of the microstructure during thermal cycling. The third stage consists of a computer modeling and simulation effort that utilizes the starting microstructure and experimental data to produce a reliability prediction of the solder joint. This approach is an improvement over current methodologies because it incorporates the microstructure and properties of the solder directly into the model and allows these properties to evolve as the microstructure changes during fatigue.

  15. Soldering in electronics assembly

    CERN Document Server

    Judd, Mike

    2013-01-01

    Soldering in Electronics Assembly discusses several concerns in soldering of electronic assemblies. The book is comprised of nine chapters that tackle different areas in electronic assembly soldering. Chapter 1 discusses the soldering process itself, while Chapter 2 covers the electronic assemblies. Chapter 3 talks about solders and Chapter 4 deals with flux. The text also tackles the CS and SC soldering process. The cleaning of soldered assemblies, solder quality, and standards and specifications are also discussed. The book will be of great use to professionals who deal with electronic assem

  16. The Lead-Free Solder Selection Method and Process Optimization Based on Design of Experiment

    Directory of Open Access Journals (Sweden)

    Wang Bing

    2013-07-01

    Full Text Available In the study, through researching the characteristic of the lead-free solder, we introduce the method of QFD (Quality Function Deployment to transform the demand of production properties and process into the technical demand of the lead-free solder, thus we could transform the demand concept of sampling into a concrete performance index. Finally we can obtain two parameters of the technological competitive power index and market competitive power index to evaluate performance of the lead-free solder through making a series of experiments. We utilize the design of experiment method to find out key parameter of process and the best collocation of parameter, which make the co planarity of tin ball descend to 149 from 178 and promote the process’s ability up to 95.2 from 85%.

  17. Coplanarity inspection of BGA solder balls based on laser interference structure light

    Science.gov (United States)

    Wei, Zhe; Xiao, Zexin; Zhang, Xuefei; Zhou, Haiying

    2011-11-01

    Using laser interference structure light for profilometry is a rapid, non-contact, full-field profile and high accuracy measuring method.And it has been a promising technique in complicated geometrical shape measurement. In this paper, a fast and cost-effective measurement method of coplanarity inspection of ball grid array (BGA) solder balls is proposed. Laser interference structure light can be obtained by using the principle of shearing interferometry. The collimated and beam expanded laser produced interference fringe by the high reflection rate optical flat. After laser interference fringe project on the surface of object and the structured light would modulated. The light signal pass through the image optical grabber and captured by the CCD image sensor. The height of each point on object can be demodulated by the imaging processing software.This method to construct the measurement appliance for coplanarity inspection of ball grid array (BGA) chip solder ball. Experiments have shown that the coplanarity measurement of BGA solder balls is very efficient and effective with the measurement. The measurement accuracy achieve micrometer level. The processing time of the measurement accuracy is less than 3s on a personal computer. This measurement appliance could completely meet the demand of measure.

  18. Thermo-mechanical investigations on the effects of the solder meniscus design in solder joint lifetime for power electronic devices

    OpenAIRE

    BOUARROUDJ, M; KHATIR, Z; Lefebvre, S.; L. Dupont

    2007-01-01

    The crack and delamination of solder joints between base plates and DCB substrates of power modules is one of the most frequently encountered failure mode and studied in literature. In this paper we present numerical effects of solder meniscus design in solder lifetime prediction. Especially, we show the effect of singular points, which appear in the border edges or corners of DCB or solder joints geometries, in mechanical stress, strain and plastic work evaluations. Furthermore the effect of...

  19. Properties of Cerium Containing Lead Free Solder

    Science.gov (United States)

    Xie, Huxiao

    With increasing concerns of the intrinsic toxicity of lead (Pb) in electronics, a series of tin (Sn) based alloys involving silver (Ag) and copper (Cu) have been proposed as replacements for Pb-Sn solder and widely accepted by industry. However, they have a higher melting point and often exhibit poorer damage tolerance than Pb-Sn alloys. Recently, a new class of alloys with trace amount of rare-earth (RE) elements has been discovered and investigated. In previous work from Prof. Chawla's group, it has been shown that cerium (Ce)-based Pb-free solder are less prone to oxidation and Sn whiskering, and exhibit desirable attributes of microstructural refinement and enhanced ductility relative to lanthanum (La)-based Sn-3.9Ag-0.7Cu (SAC) alloy. Although the formation of RESn3 was believed to be directly responsible for the enhanced ductility in RE-containing SAC solder by allowing microscopic voids to nucleate throughout the solder volume, this cavitation-based mechanism needs to be validated experimentally and numerically. Additionally, since the previous study has exhibited the realistic feasibility of Ce-based SAC lead-free solder alloy as a replacement to conventional SAC alloys, in this study, the proposed objective focuses on the in in-depth understanding of mechanism of enhanced ductility in Ce-based SAC alloy and possible issues associated with integration of this new class of solder into electronic industry, including: (a) study of long-term thermal and mechanical stability on industrial metallization, (b) examine the role of solder volume and wetting behavior of the new solder, relative to Sn-3.9Ag-0.7Cu alloys, (c) conduct experiments of new solder alloys in the form of mechanical shock and electromigration. The research of this new class alloys will be conducted in industrially relevant conditions, and the results would serve as the first step toward integration of these new, next generation solders into the industry.

  20. Comparisons of Mechanical Properties of sub-mm Lead Based and Lead Free Based Solder Using in Manufacturing of Printed Circuits

    OpenAIRE

    Alaa Hasan Ali

    2014-01-01

    This study investigates the mechanical compression properties of tin-lead and lead-free alloy spherical balls, using more than 500 samples to identify statistical variability in the properties in each alloy. Isothermal aging was done to study and compare the aging effect on the microstructure and properties. The results showed significant elastic and plastic anisotropy of tin phase in lead-free tin based solder and that was compared with simulation using a Crystal Plasticity Finite Element (C...

  1. Submicron accuracy optimization for laser beam soldering processes

    Science.gov (United States)

    Beckert, Erik; Burkhardt, Thomas; Hornaff, Marcel; Kamm, Andreas; Scheidig, Ingo; Stiehl, Cornelia; Eberhardt, Ramona; Tünnermann, Andreas

    2010-02-01

    Laser beam soldering is a packaging technology alternative to polymeric adhesive bonding in terms of stability and functionality. Nevertheless, when packaging especially micro optical and MOEMS systems this technology has to fulfil stringent requirements for accuracy in the micron and submicron range. Investigating the assembly of several laser optical systems it has been shown that micron accuracy and submicron reproducibility can be reached when using design-of-experiment optimized solder processes that are based on applying liquid solder drops ("Solder Bumping") onto wettable metalized joining surfaces of optical components. The soldered assemblies were subject to thermal cycles and vibration/ shock test also.

  2. Solder flow over fine line PWB surface finishes

    Energy Technology Data Exchange (ETDEWEB)

    Hosking, F.M.; Hernandez, C.L.

    1998-08-01

    The rapid advancement of interconnect technology has stimulated the development of alternative printed wiring board (PWB) surface finishes to enhance the solderability of standard copper and solder-coated surfaces. These new finishes are based on either metallic or organic chemistries. As part of an ongoing solderability study, Sandia National Laboratories has investigated the solder flow behavior of two azole-based organic solderability preservations, immersion Au, immersion Ag, electroless Pd, and electroless Pd/Ni on fine line copper features. The coated substrates were solder tested in the as-fabricated and environmentally-stressed conditions. Samples were processed through an inerted reflow machine. The azole-based coatings generally provided the most effective protection after aging. Thin Pd over Cu yielded the best wetting results of the metallic coatings, with complete dissolution of the Pd overcoat and wetting of the underlying Cu by the flowing solder. Limited wetting was measured on the thicker Pd and Pd over Ni finishes, which were not completely dissolved by the molten solder. The immersion Au and Ag finishes yielded the lowest wetted lengths, respectively. These general differences in solderability were directly attributed to the type of surface finish which the solder came in contact with. The effects of circuit geometry, surface finish, stressing, and solder processing conditions are discussed.

  3. Interface between Sn-Sb-Cu solder and copper substrate

    International Nuclear Information System (INIS)

    Highlights: → New lead-free solder materials based on Sn-Sb-Cu were designed and prepared. → Melting and solidification temperatures of the solders have been determined. → Cu-substrate/solder interaction has been analyzed and quantified. → Phases formed at the solder-substrate interface have been identified. → Composition and soldering atmospheres were correlated with joint strength. - Abstract: Influence of antimony and copper in Sn-Sb-Cu solder on the melting and solidification temperatures and on the microstructure of the interface between the solder and copper substrate after wetting the substrate at 623 K for 1800 s were studied. Microstructure of the interface between the solder and copper substrates in Cu-solder-Cu joints prepared at the same temperature for 1800 s was observed and shear strength of the joints was measured. Influence of the atmosphere - air with the flux and deoxidising N2 + 10H2 gas - was taken into account. Thermal stability and microstructure were studied by differential scanning calorimetry (DSC), light microscopy, scanning electron microscopy (SEM) with energy-dispersive spectrometry (EDS) and X-ray diffraction (XRD). Melting and solidification temperatures of the solders were determined. An interfacial transition zone was formed by diffusion reaction between solid copper and liquid solder. At the interface Cu3Sn and Cu6Sn5 phases arise. Cu3Sn is adjacent to the Cu substrate and its thickness decreases with increasing the amount of copper in solder. Scallop Cu6Sn5 phase is formed also inside the solder drop. The solid solution Sn(Sb) and SbSn phase compose the interior of the solder drop. Shear strength of the joints measured by push-off method decreases with increasing Sb concentration. Copper in the solder shows even bigger negative effect on the strength.

  4. Soldering-based easy packaging of thin polyimide multichannel electrodes for neuro-signal recording

    International Nuclear Information System (INIS)

    We propose a novel packaging method for preparing thin polyimide (PI) multichannel microelectrodes. The electrodes were connected simply by making a via-hole at the interconnection pad of a thin PI electrode, and a nickel (Ni) ring was constructed by electroplating through the via-hole to permit stable soldering with strong adhesion to the electrode and the printed circuit board. The electroplating conditions were optimized for the construction of a well-organized Ni ring. The electrical properties of the packaged electrode were evaluated by fabricating and packaging a 40-channel thin PI electrode. Animal experiments were performed using the packaged electrode for high-resolution recording of somatosensory evoked potential from the skull of a rat. The in vivo and in vitro tests demonstrated that the packaged PI electrode may be used broadly for the continuous measurement of bio-signals or for neural prosthetics. (paper)

  5. Soldering-based easy packaging of thin polyimide multichannel electrodes for neuro-signal recording

    Science.gov (United States)

    Baek, Dong-Hyun; Han, Chang-Hee; Jung, Ha-Chul; Kim, Seon Min; Im, Chang-Hwan; Oh, Hyun-Jik; Jungho Pak, James; Lee, Sang-Hoon

    2012-11-01

    We propose a novel packaging method for preparing thin polyimide (PI) multichannel microelectrodes. The electrodes were connected simply by making a via-hole at the interconnection pad of a thin PI electrode, and a nickel (Ni) ring was constructed by electroplating through the via-hole to permit stable soldering with strong adhesion to the electrode and the printed circuit board. The electroplating conditions were optimized for the construction of a well-organized Ni ring. The electrical properties of the packaged electrode were evaluated by fabricating and packaging a 40-channel thin PI electrode. Animal experiments were performed using the packaged electrode for high-resolution recording of somatosensory evoked potential from the skull of a rat. The in vivo and in vitro tests demonstrated that the packaged PI electrode may be used broadly for the continuous measurement of bio-signals or for neural prosthetics.

  6. Microsoldering using a YAG laser: on lead-free solder

    Science.gov (United States)

    Nakahara, Sumio; Kamata, Tatsuya; Yoneda, Noriyuki; Hisada, Shigeyoshi; Fujita, Takeyoshi

    2000-11-01

    Solderability of conventional Sn-37Pb solder pastes and Pb- free alloys (Sn-43Bi and Sn-2Ag-5Bi-0.5Cu) were examined on micro soldering using a YAG laser. Experiments were performed in order to determine the range of soldering parameters of a laser power density and an irradiation time for obtaining an appropriate wettability based on a visual inspection by a Japanese Industrial Standard. And the laser soldering processes were monitored by measuring temperature change inside solder joint (solder and Cu pad) and on a surface of a chip component. Next joining strength of chip components for surface mounting soldered on printed circuit board (glass epoxy) was tested on application thickness of solder paste (0.2, 0.3, and 0.4 mm). In addition, joining strength characteristics at different power density and materials were examined around thermal shock test by the gas phase method. As a result, characteristics of Sn-Ag-Bi-Cu (Pb-free) solder paste are equivalent to that of Sn-Pb solder paste.

  7. In situ measurement of electromigration-induced transient stress in Pb-free Sn-Cu solder joints by synchrotron radiation based X-ray polychromatic microdiffraction

    OpenAIRE

    CHEN, KAI

    2011-01-01

    Electromigration-induced hydrostatic elastic stress in Pb-free SnCu solder joints was studied by in situ synchrotron X-ray white beam microdiffraction. The elastic stresses in two different grains with similar crystallographic orientation, one located at the anode end and the other at the cathode end, were analyzed based on the elastic anisotropy of the Beta-Sn crystal structure. The stress in the grain at the cathode end remained constant except for temperature fluctuations, while the compre...

  8. Prototyping lead-free solders on hand-soldered, through-hole circuit boards

    Energy Technology Data Exchange (ETDEWEB)

    Vianco, P.T. [Sandia National Labs., Albuquerque, NM (United States); Mizik, P.M. [Allied-Signal Aerospace Co., Kansas City, MO (United States). Kansas City Div.

    1993-12-31

    The lead-free solders 96.5Sn-3.5Ag (wt %), 95.5Sn-4.0Cu-0.5Ag, 91. 84Sn-3.33Ag-4.83Bi were used in the assembly of a through-hole circuit board to determine the feasibility of their suitability in hand soldering processes. Prototypes assembled with 63Sn-37Pb solder were manufactured to serve as control units. Implementation of the lead-free alloys were performed with a rosin-based, mildly activated (RMA) flux and a 700{degree}F soldering tip. A procedure was developed to remove the tin-lead finish from the leaded components and replace it with a 100Sn hot dipped coating. Assembly feasibility was demonstrated for all three lead-free solders. Defect counts were greater than observed with the tin-lead control alloy; however, the number of defects diminished with experience gained by the operator. Visual examination of the solder joints indicated satisfactory wetting of both the device leads and circuit board land with no apparent damage to the underlying laminate nor to the device packages. Cross sections of the lead-free solder joints showed that the were more susceptible to void formation within the holes than was the case with the tin-lead solder. Some cracking was observed at the interface between the Sn-Ag-Bi solder and the copper lands; the relatively high strength of this solder and fast cooling rate of the hand assembly process was believed responsible for this defect.

  9. Thermal Analysis of the Sn-Ag-Cu-In Solder Alloy

    DEFF Research Database (Denmark)

    Sopousek, J.; Palcut, Marián; Hodúlová, Erika;

    2010-01-01

    The tin-based alloy Sn-1.5Ag-0.7Cu-9.5In (composition in wt.%) is a potential candidate for lead-free soldering at temperatures close to 200°C due to the significant amount of indium. Samples of Sn-1.5Ag-0.7Cu-9.5In were prepared by controlled melting of the pure elements, followed by quenching...

  10. Evaluation of Die-Soldering and Erosion Resistance of High Velocity Oxy-Fuel Sprayed MoB-Based Cermet Coatings

    Science.gov (United States)

    Khan, Faisal Farooq; Bae, Gyuyeol; Kang, Kicheol; Na, Hyuntaek; Kim, Junghwan; Jeong, Taeho; Lee, Changhee

    2011-09-01

    Soldering and erosion are two of the biggest serious problems faced in the die-casting industries. Cermet coatings utilized by high-velocity oxy-fuel (HVOF) spray technology have been developed in an attempt to overcome these problems. MoB-based cermet feedstock powders (MoB/NiCr and MoB/CoCr) were deposited on SKD61 (AISI H-13) substrates used as a preferred die (mold) material. Microstructural and mechanical properties of the coatings have been characterized by scanning electron microscopy, x-ray diffraction, Romulus bond strength test, and Vickers microhardness test. The durability of these coatings on cylindrical specimens against soldering also has been investigated by immersing in molten aluminum alloy (ADC-12) for 25 h at 670 °C and subsequently, compared with that of NiCr and CoMoCr coatings. Both types of MoB-based cermet coatings have shown high soldering resistance as negligible intermetallic formation occurred during the immersion test. This result is attributed to the existence of multiple inert borides in the coatings. The coatings also showed excellent mechanical properties. MoB/NiCr, in particular, showed higher bond strength, hardness, and wear resistance than MoB/CoCr. This suggests that MoB/NiCr will show higher durability than MoB/CoCr, NiCr, and CoMoCr during high pressure die-casting of aluminum alloys.

  11. Oxidation and reduction kinetics of eutectic SnPb, InSn, and AuSn: a knowledge base for fluxless solder bonding applications

    OpenAIRE

    Kuhmann, Jochen Friedrich; Preuss, A.; Adolphi, B.; K. Maly; Wirth, T.; Oesterle, W.; Pittroff, W.; Weyer, G.; Fanciulli, M.

    1998-01-01

    For microelectronics and especially for upcoming new packaging technologies in micromechanics and photonics fluxless, reliable and economic soldering technologies are needed. In this article, we consequently focus on the oxidation and reduction kinetics of three commonly used eutectic solder alloys: (1) SnPb; (2) InSn; (3) AuSn. The studies of the oxidation kinetics show that the growth of the native oxide, which covers the solder surfaces from the start of all soldering operations is self-li...

  12. Development of lead-free solders for high-temperature applications

    DEFF Research Database (Denmark)

    Chidambaram, Vivek

    This work also reviews the alternative technologies for replacing the high-temperature soldering since it was determined that even the expensive candidate alloys involving Au too could not cover the spectrum of properties required for being accepted as a standard soft solder for high-temperature ......This work also reviews the alternative technologies for replacing the high-temperature soldering since it was determined that even the expensive candidate alloys involving Au too could not cover the spectrum of properties required for being accepted as a standard soft solder for high......-temperature applications. Unfortunately, even the substitute technologies that are currently being developed cannot address several critical issues of high-temperature soldering. Therefore, further research and development of high-temperature lead-free soldering is obviously needed. It is hoped that this thesis can serve...

  13. Characterization of Low-Melting-Point Sn-Bi-In Lead-Free Solders

    Science.gov (United States)

    Li, Qin; Ma, Ninshu; Lei, YongPing; Lin, Jian; Fu, HanGuang; Gu, Jian

    2016-02-01

    Development of lead-free solders with low melting temperature is important for substitution of Pb-based solders to reduce direct risks to human health and the environment. In the present work, Sn-Bi-In solders were studied for different ratios of Bi and Sn to obtain solders with low melting temperature. The microstructure, thermal properties, wettability, mechanical properties, and reliability of joints with Cu have been investigated. The results show that the microstructures of the Sn-Bi-In solders were composed of β-Sn, Bi, and InBi phases. The intermetallic compound (IMC) layer was mainly composed of Cu6Sn5, and its thickness increased slightly as the Bi content was increased. The melting temperature of the solders was around 100°C to 104°C. However, when the Sn content exceeded 50 wt.%, the melting range became larger and the wettability became worse. The tensile strength of the solder alloys and solder joints declined with increasing Bi content. Two fracture modes (IMC layer fracture and solder/IMC mixed fracture) were found in solder joints. The fracture mechanism of solder joints was brittle fracture. In addition, cleavage steps on the fracture surface and coarse grains in the fracture structure were comparatively apparent for higher Bi content, resulting in decreased elongation for both solder alloys and solder joints.

  14. Reliability of Sn-3.5Ag Solder Joints in High Temperature Packaging Applications

    Energy Technology Data Exchange (ETDEWEB)

    Muralidharan, Govindarajan [ORNL; Kurumaddali, Nalini Kanth [ORNL; Kercher, Andrew K [ORNL; Leslie, Dr Scott [Powerex Inc

    2010-01-01

    There is a significant need for next generation, high performance power electronic packages and systems with wide band gap devices to operate at high temperatures in automotive and electricity transmission applications. Sn-3.5Ag solder is a candidate for use in such packages with potential operating temperatures up to 200oC. However, there is a need to understand thermal cycling reliability of Sn-3.5Ag solders subject to such operating conditions. The results of a study on the damage evolution occurring in large area Sn-3.5Ag solders joints between silicon dies and DBC substrates subject to thermal cycling between 200oC and 5oC is presented in this paper. Damage accumulation was followed using high resolution X-ray radiography techniques while nonlinear finite element models were developed based on the mechanical property data available in literature to understand the relationship between the stress state within the solder joint and the damage evolution occurring under thermal cycling conditions. It was observed that regions of damage observed in the experiments do not correspond to the finite element predictions of the location of regions of maximum plastic work.

  15. A Study of Solder Alloy Ductility for Cryogenic Applications

    Science.gov (United States)

    Lupinacci, A.; Shapiro, A. A.; Suh, J-O.; Minor, A. M.

    2013-01-01

    For aerospace applications it is important to understand the mechanical performance of components at the extreme temperature conditions seen in service. For solder alloys used in microelectronics, cryogenic temperatures can prove problematic. At low temperatures Sn-based solders undergo a ductile to brittle transition that leads to brittle cracks, which can result in catastrophic failure of electronic components, assemblies and spacecraft payloads. As industrial processes begin to move away from Pb-Sn solder, it is even more critical to characterize the behavior of alternative Sn-based solders. Here we report on initial investigations using a modified Charpy test apparatus to characterize the ductile to brittle transformation temperature of nine different solder systems.

  16. Laser-activated protein solder for peripheral nerve repair

    Science.gov (United States)

    Trickett, Rodney I.; Lauto, Antonio; Dawes, Judith M.; Owen, Earl R.

    1995-05-01

    A 100 micrometers core optical fiber-coupled 75 mW diode laser operating at a wavelength of 800 nm has been used in conjunction with a protein solder to stripe weld severed rat tibial nerves, reducing the long operating time required for microsurgical nerve repair. Welding is produced by selective laser denaturation of the albumin based solder which contains the dye indocyanine green. Operating time for laser soldering was 10 +/- 5 min. (n equals 20) compared to 23 +/- 9 min. (n equals 10) for microsuturing. The laser solder technique resulted in patent welds with a tensile strength of 15 +/- 5 g, while microsutured nerves had a tensile strength of 40 +/- 10 g. Histopathology of the laser soldered nerves, conducted immediately after surgery, displayed solder adhesion to the outer membrane with minimal damage to the inner axons of the nerves. An in vivo study is under way comparing laser solder repaired tibial nerves to conventional microsuture repair. At the time of submission 15 laser soldered nerves and 7 sutured nerves were characterized at 3 months and showed successful regeneration with compound muscle action potentials of 27 +/- 8 mV and 29 +/- 8 mW respectively. A faster, less damaging and long lasting laser based anastomotic technique is presented.

  17. Microstructural Evolution of Lead-Free Solder Joints in Ultrasonic-Assisted Soldering

    Science.gov (United States)

    Ji, Hongjun; Wang, Qiang; Li, Mingyu

    2016-01-01

    Solder joint reliability greatly depends on the microstructure of the solder matrix and the morphology of intermetallic compounds (IMCs) in the joints. Addition of strengthening phases such as carbon nanotubes and ceramic particles to solder joints to improve their properties has been widely studied. In this work, ultrasonic vibration (USV) of casting ingots was applied to considerably improve their microstructure and properties, and the resulting influence on fluxless soldering of Cu/Sn-3.0Ag-0.5Cu/Cu joints and their microstructural evolution was investigated. It was demonstrated that USV application during reflow of Sn-based solder had favorable effects on β-Sn grain size refinement as well as the growth and distribution of various IMC phases within the joints. The β-Sn grain size was significantly refined as the ultrasound power was increased, with a reduction of almost 90% from more than 100 μm to below 10 μm. Long and large Cu6Sn5 tubes in the solder matrix of the joints were broken into tiny ones. Needle-shaped Ag3Sn was transformed into flake-shaped. These IMCs were mainly precipitated along β-Sn phase boundaries. High-temperature storage tests indicated that the growth rate of interfacial IMCs in joints formed with USV was slower than in conventional reflow joints. The mechanisms of grain refinement and IMC fragmentation are discussed and related to the ultrasonic effects.

  18. Integration of environmentally compatible soldering technologies for waste minimization

    International Nuclear Information System (INIS)

    There has been a concentrated effort throughout the international microelectronics industry to phase out chlorofluorocarbon (CFC) materials and alleviate the serious problem of ozone depletion created by the release of CFCS. The development of more environmentally compatible manufacturing technologies is the cornerstone of this effort. Alternative materials and processes for cleaning and soldering have received special attention. Electronic. soldering typically utilizes rosin-based fluxes to promote solder wettability. Flux residues must be removed from the soldered parts when high product reliability is essential. Halogenated or CFC solvents have been the principle chemicals used to clean the residues. With the accelerated push to eliminate CFCs in the US by 1995, CFC-free solvents, aqueous-based cleaning, water soluble or ''no clean'' fluxes, and fluxless soldering technologies are being developed and quickly integrated into manufacturing practice. Sandia's Center for Solder Science and Technology has been ch g a variety of fluxless and alternative soldering technologies for DOE's waste minimization program. The work has focused on controlled atmosphere, laser, and ultrasonic fluxless soldering, protective metallic and organic coatings, and fluxes which have water soluble or low solids-based chemistries. With the increasing concern that Pb will also be banned from electronic soldering, Sandia has been characterizing the wetting, aging, and mechanical properties of Pb-fire solder alloys. The progress of these integrated studies will be discussed. Their impact on environmentally compatible manufacturing will be emphasized. Since there is no universal solution to the various environmental, safety, and health issues which currently face industry, the proposed technologies offer several complementary materials and processing options from which one can choose

  19. Diode laser soldering using a lead-free filler material for electronic packaging structures

    Energy Technology Data Exchange (ETDEWEB)

    Chaminade, C. [IREPA LASER, Parc d' innovation, Pole API, 67400 Illkirch (France)]. E-mail: cc@irepa.u-strabg.fr; Fogarassy, E. [IREPA LASER, Parc d' innovation, Pole API, 67400 Illkirch (France); Boisselier, D. [IREPA LASER, Parc d' innovation, Pole API, 67400 Illkirch (France)

    2006-04-30

    As of today, several lead-free soldering pastes have been qualified for currently used soldering process. Regarding the new potential of laser-assisted soldering processes, the behaviour of the SnAgCu soldering paste requires, however, new investigations. In the first part of this study, the specific temperature profile of a laser soldering process is investigated using a high power diode laser (HPDL). These experimental results are compared to a thermal simulation developed for this specific application. The second part of this work deals with the diffusion of the tin-based filler material through the nickel barrier using the information extracted from the temperature simulations.

  20. Diode laser soldering using a lead-free filler material for electronic packaging structures

    International Nuclear Information System (INIS)

    As of today, several lead-free soldering pastes have been qualified for currently used soldering process. Regarding the new potential of laser-assisted soldering processes, the behaviour of the SnAgCu soldering paste requires, however, new investigations. In the first part of this study, the specific temperature profile of a laser soldering process is investigated using a high power diode laser (HPDL). These experimental results are compared to a thermal simulation developed for this specific application. The second part of this work deals with the diffusion of the tin-based filler material through the nickel barrier using the information extracted from the temperature simulations

  1. Oxidation and reduction kinetics of eutectic SnPb, InSn, and AuSn: a knowledge base for fluxless solder bonding applications

    DEFF Research Database (Denmark)

    Kuhmann, Jochen Friedrich; Preuss, A.; Adolphi, B.;

    1998-01-01

    For microelectronics and especially for upcoming new packaging technologies in micromechanics and photonics fluxless, reliable and economic soldering technologies are needed. In this article, we consequently focus on the oxidation and reduction kinetics of three commonly used eutectic solder alloys......: (1) SnPb; (2) InSn; (3) AuSn. The studies of the oxidation kinetics show that the growth of the native oxide, which covers the solder surfaces from the start of all soldering operations is self-limiting. The rate of oxidation on the molten, metallic solder surfaces is significantly reduced...... and reduction kinetics, are applied to flip-chip (FC) bonding experiments in vacuum with and without the injection of H2. Wetting in vacuum is excellent but the self-alignment during flip-chip soldering is restricted. The desired, perfectly self-aligned FC-bonds have been only achieved, using evaporated...

  2. Frictional Behavior of Fe-based Cladding Candidates for PWR

    International Nuclear Information System (INIS)

    After the recent nuclear disaster at Fukushima Daiichi reactors, there is a growing consensus on the development of new fuel systems (i.e., accident-tolerant fuel, ATF) that have high safety margins under design-basis accident (DBA) and beyond design-basis accident (BDBA). A common objective of various developing candidates is to archive the outstanding corrosion-resistance under severe accidents such as DBA and DBDA conditions for decreasing hydrogen production and increasing coping time to respond to severe accidents. ATF could be defined as new fuel/cladding system with enhanced accident tolerant to loss of active cooling in the core for a considerably longer time period under severe accidents while maintaining or improving the fuel performance during normal operations. This means that, in normal operating conditions, new fuel systems should be applicable to current operating PWRs for suppressing various degradation mechanisms of current fuel assembly without excessive design changes. When considering that one of the major degradation mechanisms of PWR fuel assemblies is a grid-to-rod fretting (GTRF), it is necessary to examine the tribological behavior of various ATF candidates at initial development stage. In this study, friction and reciprocating wear behavior of two kinds of Fe-based ATF candidates were examined with a reciprocating wear tests at room temperature (RT) air and water. The objective is to examine the compatibilities of these Fe-based alloys against current Zr-based alloy properties, which is used as major structural materials of PWR fuel assemblies. The reciprocating wear behaviors of Fe-based accident-tolerant fuel cladding candidates against current Zr-based alloy has been studied using a reciprocating sliding wear tester in room temperature air and water. Frictional behavior and wear depth were used for evaluating the applicability and compatibilities of Fe-based candidates without significant design changes of PWR fuel assemblies

  3. Frictional Behavior of Fe-based Cladding Candidates for PWR

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Young-Ho; Kim, Hyung-Kyu [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of); Byun, Thak Sang [Oak Ridge National Lab., Oak Ridge (United States)

    2014-10-15

    After the recent nuclear disaster at Fukushima Daiichi reactors, there is a growing consensus on the development of new fuel systems (i.e., accident-tolerant fuel, ATF) that have high safety margins under design-basis accident (DBA) and beyond design-basis accident (BDBA). A common objective of various developing candidates is to archive the outstanding corrosion-resistance under severe accidents such as DBA and DBDA conditions for decreasing hydrogen production and increasing coping time to respond to severe accidents. ATF could be defined as new fuel/cladding system with enhanced accident tolerant to loss of active cooling in the core for a considerably longer time period under severe accidents while maintaining or improving the fuel performance during normal operations. This means that, in normal operating conditions, new fuel systems should be applicable to current operating PWRs for suppressing various degradation mechanisms of current fuel assembly without excessive design changes. When considering that one of the major degradation mechanisms of PWR fuel assemblies is a grid-to-rod fretting (GTRF), it is necessary to examine the tribological behavior of various ATF candidates at initial development stage. In this study, friction and reciprocating wear behavior of two kinds of Fe-based ATF candidates were examined with a reciprocating wear tests at room temperature (RT) air and water. The objective is to examine the compatibilities of these Fe-based alloys against current Zr-based alloy properties, which is used as major structural materials of PWR fuel assemblies. The reciprocating wear behaviors of Fe-based accident-tolerant fuel cladding candidates against current Zr-based alloy has been studied using a reciprocating sliding wear tester in room temperature air and water. Frictional behavior and wear depth were used for evaluating the applicability and compatibilities of Fe-based candidates without significant design changes of PWR fuel assemblies

  4. A study on the Joining Properties of Bi-2212 High-Tc Superconducting Tube and Indium Solder

    International Nuclear Information System (INIS)

    As a material for SFCL(Superconducting Fault Current Limiter), BSCCO tube with metal stabilizer is a promising candidate, assuring the stability and large power capacity, For the application, the proper soldering technique, which overcome the difficulties of the joining between BSCCO and metal stabilizer, is required. In this study, after soldering In-Bi solder and In-Sn solder with BSCCO superconductor, welding properties between BSCCO and solders were investigated. Because ceramic materials is difficult to weld, Ag electro-plating on BSCCO 2212 is used for intermetallic layer. To find out the best welding condition for superconductor, soldering is tested in the maximum temperature from 155 degrees C to 165 degrees C in the reflow oven. By investigating the composition and thickness of IMC (lntermetallic Compound) created in the reaction of Ag with solder, we analyzed the welding properties of High-Tc superconductor from a micro point of view.

  5. Utilization of Pb-free solders in MEMS packaging

    Science.gov (United States)

    Selvaduray, Guna S.

    2003-01-01

    Soldering of components within a package plays an important role in providing electrical interconnection, mechanical integrity and thermal dissipation. MEMS packages present challenges that are more complex than microelectronic packages because they are far more sensitive to shock and vibration and also require precision alignment. Soldering is used at two major levels within a MEMS package: at the die attach level and at the component attach level. Emerging environmental regulations worldwide, notably in Europe and Japan, have targeted the elimination of Pb usage in electronic assemblies, due to the inherent toxicity of Pb. This has provided the driving force for development and deployment of Pb-free solder alloys. A relatively large number of Pb-free solder alloys have been proposed by various researchers and companies. Some of these alloys have also been patented. After several years of research, the solder alloy system that has emerged is based on Sn as a major component. The electronics industry has identified different compositions for different specific uses, such as wave soldering, surface mount reflow, etc. The factors that affect choice of an appropriate Pb-free solder can be divided into two major categories, those related to manufacturing, and those related to long term reliability and performance.

  6. Passive alignment and soldering technique for optical components

    Science.gov (United States)

    Faidel, Heinrich; Gronloh, Bastian; Winzen, Matthias; Liermann, Erik; Esser, Dominik; Morasch, Valentin; Luttmann, Jörg; Leers, Michael; Hoffmann, Dieter

    2012-03-01

    The passive-alignment-packaging technique presented in this work provides a method for mounting tolerance-insensitive optical components e.g. non-linear crystals by means of mechanical stops. The requested tolerances for the angle deviation are +/-100 μrad and for the position tolerance +/-100 μm. Only the angle tolerances were investigated, because they are more critical. The measurements were carried out with an autocollimator. Fused silica components were used for test series. A solder investigation was carried out. Different types of solder were tested. Due to good solderability on air and low induced stress in optical components, Sn based solders were indicated as the most suitable solders. In addition several concepts of reflow soldering configuration were realized. In the first iteration a system with only the alignment of the yaw angle was implemented. The deviation for all materials after the thermal and mechanical cycling was within the tolerances. The solderability of BBO and LBO crystals was investigated and concepts for mounting were developed.

  7. Soldering Tested in Reduced Gravity

    Science.gov (United States)

    Struk, Peter M.; Pettegrew, Richard D.; Watson, J. Kevin; Down, Robert S.; Haylett, Daniel R.

    2005-01-01

    Whether used occasionally for contingency repair or routinely in nominal repair operations, soldering will become increasingly important to the success of future long-duration human space missions. As a result, it will be critical to have a thorough understanding of the service characteristics of solder joints produced in reduced-gravity environments. The National Center for Space Exploration Research (via the Research for Design program), the NASA Glenn Research Center, and the NASA Johnson Space Center are conducting an experimental program to explore the influence of reduced gravity environments on the soldering process. Solder joint characteristics that are being considered include solder fillet geometry, porosity, and microstructural features. Both through-hole (see the drawing and image on the preceding figure) and surface-mounted devices are being investigated. This effort (the low-gravity portion being conducted on NASA s KC-135 research aircraft) uses the soldering hardware currently available on the International Space Station. The experiment involves manual soldering by a contingent of test operators, including both highly skilled technicians and less skilled individuals to provide a skill mix that might be encountered in space mission crews. The experiment uses both flux-cored solder and solid-core solder with an externally applied flux. Other experimental parameters include the type of flux, gravitational level (nominally zero,

  8. Soldering of Nanotubes onto Microelectrodes

    DEFF Research Database (Denmark)

    Madsen, Dorte Nørgaard; Mølhave, Kristian; Mateiu, Ramona Valentina;

    2003-01-01

    Suspended bridges of individual multiwalled carbon nanotubes were fabricated inside a scanning electron microscope by soldering the nanotube onto microelectrodes with highly conducting gold-carbon material. By the decomposition of organometallic vapor with the electron beam, metal-containing solder...... bonds were formed at the intersection of the nanotube and the electrodes. Current-voltage curves indicated metallic conduction of the nanotubes, with resistances in the range of 9-29 kOmega. Bridges made entirely of the soldering material exhibited resistances on the order of 100 Omega, and the solder...... bonds were consistently found to be mechanically stronger than the carbon nanotubes....

  9. In situ measurement of electromigration-induced transient stress in Pb-free Sn-Cu solder joints by synchrotron radiation based X-ray polychromatic microdiffraction

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Kai; Tamura, Nobumichi; Kunz, Martin; Tu, King-Ning; Lai, Yi-Shao

    2009-05-15

    Electromigration-induced hydrostatic elastic stress in Pb-free SnCu solder joints was studied by in situ synchrotron X-ray white beam microdiffraction. The elastic stresses in two different grains with similar crystallographic orientation, one located at the anode end and the other at the cathode end, were analyzed based on the elastic anisotropy of the {beta}-Sn crystal structure. The stress in the grain at the cathode end remained constant except for temperature fluctuations, while the compressive stress in the grain at the anode end was built-up as a function of time during electromigration until a steady state was reached. The measured compressive stress gradient between the cathode and the anode is much larger than what is needed to initiate Sn whisker growth. The effective charge number of {beta}-Sn derived from the electromigration data is in good agreement with the calculated value.

  10. In situ measurement of electromigration-induced transient stress in Pb-free Sn-Cu solder joints by synchrotron radiation based X-ray polychromatic microdiffraction

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Kai; Tamura, Nobumichi; Kunz, Martin; Tu, King-Ning; Lai, Yi-Shao

    2009-12-01

    Electromigration-induced hydrostatic elastic stress in Pb-free SnCu solder joints was studied by in situ synchrotron X-ray white beam microdiffraction. The elastic stresses in two different grains with similar crystallographic orientation, one located at the anode end and the other at the cathode end, were analyzed based on the elastic anisotropy of the Beta-Sn crystal structure. The stress in the grain at the cathode end remained constant except for temperature fluctuations, while the compressive stress in the grain at the anode end was built-up as a function of time during electromigration until a steady state was reached. The measured compressive stress gradient between the cathode and the anode is much larger than what is needed to initiate Sn whisker growth. The effective charge number of Beta-Sn derived from the electromigration data is in good agreement with the calculated value.

  11. Closure of incision in cataract surgery in-vivo using a temperature controlled laser soldering system based on a 1.9μm semiconductor laser

    Science.gov (United States)

    Gabay, Ilan; Basov, Svetlana; Varssano, David; Barequet, Irina; Rosner, Mordechai; Rattunde, Marcel; Wagner, Joachim; Platkov, Max; Harlev, Mickey; Rossman, Uri; Katzir, Abraham

    2016-03-01

    In phacoemulsification-based cataract surgery, a corneal incision is made and is then closed by hydration of the wound lips, or by suturing. We developed a system for sealing such an incision by soldering with a semiconductor disk laser (λ=1.9μm), under close temperature control. The goal was to obtain stronger and more watertight adhesion. The system was tested on incisions in the corneas of 15 eyes of pigs, in-vivo. Optical Coherent Tomography (OCT) and histopathologic examination showed little thermal damage and good apposition. The measured average burst pressure was 1000+/-30mmHg. In the future, this method wound may replace suturing of corneal wounds, including in traumatic corneal laceration and corneal transplantation.

  12. Quantitative Analysis of Porosity and Transport Properties by FIB-SEM 3D Imaging of a Solder Based Sintered Silver for a New Microelectronic Component

    Science.gov (United States)

    Rmili, W.; Vivet, N.; Chupin, S.; Le Bihan, T.; Le Quilliec, G.; Richard, C.

    2016-04-01

    As part of development of a new assembly technology to achieve bonding for an innovative silicon carbide (SiC) power device used in harsh environments, the aim of this study is to compare two silver sintering profiles and then to define the best candidate for die attach material for this new component. To achieve this goal, the solder joints have been characterized in terms of porosity by determination of the morphological characteristics of the material heterogeneities and estimating their thermal and electrical transport properties. The three dimensional (3D) microstructure of sintered silver samples has been reconstructed using a focused ion beam scanning electron microscope (FIB-SEM) tomography technique. The sample preparation and the experimental milling and imaging parameters have been optimized in order to obtain a high quality of 3D reconstruction. Volume fractions and volumetric connectivity of the individual phases (silver and voids) have been determined. Effective thermal and electrical conductivities of the samples and the tortuosity of the silver phase have been also evaluated by solving the diffusive transport equation.

  13. Mechanical Solder Characterisation Under High Strain Rate Conditions

    Science.gov (United States)

    Meier, Karsten; Roellig, Mike; Wiese, Steffen; Wolter, Klaus-Juergen

    2010-11-01

    Using a setup for high strain rate tensile experiments the mechanical behavior of two lead-free tin based solders is investigated. The first alloy is SnAg1.3Cu0.5Ni. The second alloy has a higher silver content but no addition of Ni. Solder joints are the main electrical, thermal and mechanical interconnection technology on the first and second interconnection level. With the recent rise of 3D packaging technologies many novel interconnection ideas are proposed with innovative or visionary nature. Copper pillar, stud bump, intermetallic (SLID) and even spring like joints are presented in a number of projects. However, soldering will remain one of the important interconnect technologies. Knowing the mechanical properties of solder joints is important for any reliability assessment, especially when it comes to vibration and mechanical shock associated with mobile applications. Taking the ongoing miniaturization and linked changes in solder joint microstructure and mechanical behavior into account the need for experimental work on that issue is not satisfied. The tests are accomplished utilizing miniature bulk specimens to match the microstructure of real solder joints as close as possible. The dogbone shaped bulk specimens have a crucial diameter of 1 mm, which is close to BGA solder joints. Experiments were done in the strain rate range from 20 s-1 to 600 s-1. Solder strengthening has been observed with increased strain rate for both SAC solder alloys. The yield stress increases by about 100% in the investigated strain rate range. The yield level differs strongly. A high speed camera system was used to assist the evaluation process of the stress and strain data. Besides the stress and strain data extracted from the experiment the ultimate fracture strain is determined and the fracture surfaces are evaluated using SEM technique considering rate dependency.

  14. Mechanical and Physical Properties of In-Zn-Ga Lead-Free Solder Alloy for Low Energy Consumption

    Science.gov (United States)

    Ervina Efzan, M. N.; Nur Faziera, M. N.; Bakri Abdullah, Mohd Mustafa Al

    2016-06-01

    Due to the demand in the use of electronics devices in industry, the usage of solder connections has increased. Concerning with the toxicity of lead in Sn-37Pb solder alloy, developing lead free solder alloy with low melting temperature is one of the most important issues in electronic industry. Previously, researchers found out that the most promising candidate of lead free solder alloy is Sn-3.0Ag-0.5Cu (SAC). However, the melting temperature of this solder alloy is 217°C, 34°C higher than Sn-37Pb. This can lead to high energy consumption in electronic industry. In this paper, In-Zn-Ga solder alloy was investigated as a potential candidate replacing SAC. This study covers on the physical and mechanical properties of the solder alloy. Differential Scanning Calorimetry (DSC) testing shows that this solder alloy gave low melting temperature as low as 141.31°C. The addition of Ga in In-Zn solder alloy lowered the melting temperature compared to SAC and Sn-37Pb. From coefficient of thermal expansion (CTE) analysis, the In-Zn-Ga solder alloy gives good expansion properties and able to avoid the mismatch between the solder and copper substrates. The density of In-Zn-Ga solder alloy is 6.801g/cm3, lower than SAC and Sn-37Pb. For the strength, single lap shear testing was conducted on the In-Zn-Ga solder alloy and the results is near to the strength of SAC.

  15. Eutectic Solder Bonding for Highly Manufacturable Microelectromechanical Systems Probe Card

    Science.gov (United States)

    Kim, Bonghwan

    2011-06-01

    We developed eutectic solder bonding for the microelectromechanical systems (MEMS) probe card. We tested various eutectic solder materials, such as Sn, AgSn, and AuSn, and investigated the bonding ability of Sn-based multi-element alloys and their resistance to chemical solutions. The Sn-based alloys were formed by sputtering, electroplating, and the use of solder paste. According to our experimental results, Sn-rich solders, such as Ag3.5Sn, Ag3.5Sn96Cu0.5, and Sn, were severely damaged by silicon wet etchant such as potassium hydroxide (KOH) and tetramethylammonium hydroxide (TMAH). On the other hand Au80Sn20 was resistant to those chemicals. In order to verify the joint bondability of the solders, we used a cantilever probe beam, and bump which were made of nickel and nickel alloy. After flip-chip bonding of the cantilever beam and the bump with Au80Sn20 solder paste, we measured the contact force to verify the mechanical strength. We then re-inspected it with X-rays and found no voids in the joint.

  16. Microstructure-based modeling of the ageing effect on the deformation behavior of the eutectic micro-constituent in SnAgCu lead-free solder

    International Nuclear Information System (INIS)

    The eutectic micro-constituent in SnAgCu solder governs the deformation behavior of the joint as it shows better deformation resistance than the Sn dendrites and occupies a high volume percentage of the whole solder. The main scope of this study is to develop a three-dimensional (3-D) homogenization model taking into account the microstructural evolution in the eutectic micro-constituent of SnAgCu solder in order to simulate the change in mechanical behavior of the joint caused by isothermal ageing. For this purpose, 3-D configurations of Ag3Sn and Cu6Sn5 intermetallic compounds (IMCs) in near-eutectic SnAgCu solder are visualized in the as-soldered condition and after ageing by focused ion beam/scanning electron microscopy tomography. The tomographic images are used to generate feature-preserving finite element meshes of the actual microstructures. The representative volume element size and constitutive behavior of the eutectic mixture in the two conditions are determined by a numerical homogenization procedure. The results show a considerable reduction in the yield stress level of the eutectic micro-constituent after ageing of the solder joint. It is shown that the increase in the inter-particle spacing and decrease in the aspect ratio of IMCs due to ageing cause a significant change in the strain distribution in the tin matrix, which leads to a lower contribution of IMCs in load-sharing and yield strength of aged solder. The elastic–plastic properties of as-soldered and aged eutectic mixtures are determined by nanoindentation. The results of homogenization are validated through comparison with experimental results and prediction of the dislocation detachment theory.

  17. Influence on the soldered seam properties with large gap widths by heat treatment

    International Nuclear Information System (INIS)

    Soldering tests were performed on the nickel base alloy NiCr 20 TiAl with the soldering material NiCrSi. It is seen that soldered seams of over 100 μm width are very brittle. The brittleness is due to the silicides formed during soldering. The ductility behaviour can be considerably improved by an annealing treatment after soldering which does not affect the properties of the basic material. This ductility-increasing heat treatment can also be applied to other soldered joints, the optimum temperatures and annealing times being determined by metallographic and technological investigations. Spot sampling under the actual operational conditions is recommended prior to introducing this heat treatment step into the fabrication. (orig./LH)

  18. Study of Direct Bonding Ceramics with Metal Using Sn2La Solder

    Directory of Open Access Journals (Sweden)

    Roman Koleňák

    2015-01-01

    Full Text Available The aim of this research was to study the direct bonding of ceramic materials, mainly Al2O3 and selected metals, with primary attention given to Cu substrate. Soldering was performed with Sn-based solder alloyed with 2% La. We found that the bond formation between Sn2La solder and Al2O3 occurs at the activation of lanthanum phases in solder by ultrasound. Lanthanum in the solder becomes oxidised in air during the soldering process. However, due to ultrasonic activation, the lanthanum particles are distributed to the boundary with ceramic material. A uniformly thin layer containing La, 1.5 µm in thickness, is formed on the boundary with Al2O3 material, ensuring both wetting and joint formation. The shear strength with Al2O3 ceramics is 7.5 MPa. Increased strength to 13.5 MPa was observed with SiC ceramics.

  19. Corrosive microenvironments at lead solder surfaces arising from galvanic corrosion with copper pipe.

    Science.gov (United States)

    Nguyen, Caroline K; Stone, Kendall R; Dudi, Abhijeet; Edwards, Marc A

    2010-09-15

    As stagnant water contacts copper pipe and lead solder (simulated soldered joints), a corrosion cell is formed between the metals in solder (Pb, Sn) and the copper. If the resulting galvanic current exceeds about 2 μA/cm(2), a highly corrosive microenvironment can form at the solder surface, with pH < 2.5 and chloride concentrations at least 11 times higher than bulk water levels. Waters with relatively high chloride tend to sustain high galvanic currents, preventing passivation of the solder surface, and contributing to lead contamination of potable water supplies. The total mass of lead corroded was consistent with predictions based on the galvanic current, and lead leaching to water was correlated with galvanic current. If the concentration of sulfate in the water increased relative to chloride, galvanic currents and associated lead contamination could be greatly reduced, and solder surfaces were readily passivated. PMID:20738129

  20. Trinocular stereo vision method based on mesh candidates

    Science.gov (United States)

    Liu, Bin; Xu, Gang; Li, Haibin

    2010-10-01

    One of the most interesting goals of machine vision is 3D structure recovery of the scenes. This recovery has many applications, such as object recognition, reverse engineering, automatic cartography, autonomous robot navigation, etc. To meet the demand of measuring the complex prototypes in reverse engineering, a trinocular stereo vision method based on mesh candidates was proposed. After calibration of the cameras, the joint field of view can be defined in the world coordinate system. Mesh grid is established along the coordinate axes, and the mesh nodes are considered as potential depth data of the object surface. By similarity measure of the correspondence pairs which are projected from a certain group of candidates, the depth data can be obtained readily. With mesh nodes optimization, the interval between the neighboring nodes in depth direction could be designed reasonably. The potential ambiguity can be eliminated efficiently in correspondence matching with the constraint of a third camera. The cameras can be treated as two independent pairs, left-right and left-centre. Due to multiple peaks of the correlation values, the binocular method may not satisfy the accuracy of the measurement. Another image pair is involved if the confidence coefficient is less than the preset threshold. The depth is determined by the highest sum of correlation of both camera pairs. The measurement system was simulated using 3DS MAX and Matlab software for reconstructing the surface of the object. The experimental result proved that the trinocular vision system has good performance in depth measurement.

  1. An Evaluation of Prototype Circuit Boards Assembled with a Sn-Ag Bi Solder

    International Nuclear Information System (INIS)

    An evaluation was performed which examined the aging of surface mount solder joints assembled with 91.84Sn-3.33Ag-4.83Bi solder. Defect analysis of the as-fabricated test vehicles revealed excellent solderability, good package alignment, and a minimum number of voids. Continuous DC electrical monitoring of the solder joints did not reveal opens during as many as 10,000 thermal cycles (0 C, 100 C). The solder joints exhibited no significant degradation through 2500 cycles, based upon an absence of microstructural damage and sustained shear and pull strengths of chip capacitors and J-leaded solder joints, respectively. Thermal cycles of 5000 and 10,000 resulted in some surface cracking of the solder fillets and coatings. In a few cases, deeper cracks were observed in the thinner reaches of several solder fillets. There was no deformation or cracking in the solder located in the gap between the package I/O and the circuit board pad nor in the interior of the fillets, both locations that would raise concerns of joint mechanical integrity. A drop in the chip capacitor shear strength was attributed to crack growth near the top of the fillet

  2. Damage behavior of SnAgCu/Cu solder joints subjected to thermomechanical cycling

    International Nuclear Information System (INIS)

    Highlights: •A creep–fatigue damage model based on CDM was proposed. •Designed system includes load frame, strain measure device and damage test device. •Damage evolution of solder joints was a function of accumulated inelastic strain. •Damage of solder joints is an interaction between creep and low-cycle fatigue. -- Abstract: Thermomechanical fatigue damage is a progressive process of material degradation. The objective of this study was to investigate the damage behavior of SnAgCu/Cu solder joints under thermomechanical cycling. A damage model was proposed based on continuum damage mechanics (CDM). Based upon an analysis of displacements for flip-chip solder joints subjected to thermal cycling, a special bimetallic loading frame with single-solder joint samples was designed to simulate the service conditions of actual joints in electronic packages. The assembly, which allowed for strain measurements of an individual solder joint during temperature cycling, was used to investigate the impact of stress–strain cycling on the damage behavior of SnAgCu/Cu solder joints. The characteristic parameters of the damage model were determined through thermomechanical cycling and strain measurement tests. The damage variable D = 1 − R0/R was selected, and values for it were obtained using a four-probe method for the single-solder joint samples every dozen cycles during thermomechanical cycling tests to verify the model. The results showed that the predicted damage was in good agreement with the experimental results. The damage evolution law proposed here is a function of inelastic strain, and the results showed that the damage rate of SnAgCu/Cu solder joints increased as the range of the applied strain increased. In addition, the microstructure evolution of the solder joints was analyzed using scanning electron microscopy, which provided the microscopic explanation for the damage evolution law of SnAgCu/Cu solder joints

  3. Gelatin based on Power-gel.TM. as solders for Cr.sup.4+laser tissue welding and sealing of lung air leak and fistulas in organs

    Science.gov (United States)

    Alfano, Robert R.; Tang, Jing; Evans, Jonathan M.; Ho, Peng Pei

    2006-04-25

    Laser tissue welding can be achieved using tunable Cr.sup.4+ lasers, semiconductor lasers and fiber lasers, where the weld strength follows the absorption spectrum of water. The use of gelatin and esterified gelatin as solders in conjunction with laser inducted tissue welding impart much stronger tensile and torque strengths than albumin solders. Selected NIR wavelength from the above lasers can improve welding and avoid thermal injury to tissue when used alone or with gelatin and esterified gelatin solders. These discoveries can be used to enhance laser tissue welding of tissues such as skin, mucous, bone, blood vessel, nerve, brain, liver, pancreas, spleen, kidney, lung, bronchus, respiratory track, urinary tract, gastrointestinal tract, or gynecologic tract and as a sealant for pulmonary air leaks and fistulas such as intestinal, rectal and urinary fistulas.

  4. GP2 - Sb-Sn-X alloy systems for high-temperature soldering applications

    Czech Academy of Sciences Publication Activity Database

    Borzone, G.; Delsante, S.; Li, D.; Yuan, Y.; Zanicchi, G.; Novakovic, R.; Giuranno, D.; Ricci, E.; Watson, A.; Ipser, H.; Flandorfer, H.; Schmetterer, C.; Hindler, M.; Mikula, A.; Fürtauer, S.; Rechchachb, M.; Elmahfoudi, A.; Mishra, R.; Kroupa, Aleš; Zemanová, Adéla; Bencze, L.; Fitzner, K.; Onderka, B.; Jendrzejczyk-Handzlik, D.; Lapsa, J.; Gierlotka, W.; Plevachuk, Y.; Kaban, I.; Romanowska, J.

    Brno : COST office, 2012 - (Kroupa, A.), s. 25-58 ISBN 978-80-905363-3-3. - ( COST MPO602. High-temperature Lead-free Solders. Vol 3) R&D Projects: GA MŠk(CZ) OC08053 Institutional support: RVO:68081723 Keywords : Lead-free soldering * (Sb,Sn) based materials * Thermodynamic properties * Phase diagrams Subject RIV: BJ - Thermodynamics

  5. Heat Lamps Solder Solar Array Quickly

    Science.gov (United States)

    Coyle, P. J.; Crouthamel, M. S.

    1982-01-01

    Interconnection tabs in a nine-solar-cell array have been soldered simultaneously with radiant heat. Cells and tabs are held in position for soldering by sandwiching them between compliant silicone-rubber vacuum platen and transparent polyimide sealing membrane. Heat lamps warm cells, producing smooth, flat solder joints of high quality.

  6. Dural reconstruction by fascia using a temperature-controlled CO2 laser soldering system

    Science.gov (United States)

    Forer, Boaz; Vasilyev, Tamar; Brosh, Tamar; Kariv, Naam; Gil, Ziv; Fliss, Dan M.; Katzir, Abraham

    2005-04-01

    Conventional methods for dura repair are normally based on sutures or stitches. These methods have several disadvantages: (1) The dura is often brittle, and the standard procedures are difficult and time consuming. (2) The seal is leaky. (3) The introduction of a foreign body (e.g. sutures) may cause an inflammatory response. In order to overcome these difficulties we used a temperature controlled fiber optic based CO2 laser soldering system. In a set of in vitro experiments we generated a hole of diameter 10 mm in the dura of a pig corpse, covered the hole with a segment of fascia, and soldered the fascia to the edges of the hole, using 47% bovine albumin as a solder. The soldering was carried out spot by spot, and each spot was heated to 65° C for 3-6 seconds. The soldered dura was removed and the burst pressure of the soldered patch was measured. The average value for microscopic muscular side soldering was 194 mm Hg. This is much higher than the maximal physiological pressure of the CSF fluid in the brain, which is 15 mm Hg. In a set of in vivo experiments, fascia patches were soldered on holes in five farm pigs. The long term results of these experiments were very promising. In conclusion, we have developed an advanced technique for dural reconstruction, which will find important clinical applications.

  7. Long-Term Effects of Soldering By-Products on Nickel-Coated Copper Wire

    Science.gov (United States)

    Rolin, T. D.; Hodge, R. E.

    2008-01-01

    An analysis of thirty-year-old, down graded flight cables was conducted to determine the makeup of a green material on the surface of the shielded wire near soldered areas and to ascertain if the green material had corroded the nickel-coated copper wire. Two likely candidates were possible due to the handling and environments to which these cables were exposed. The flux used to solder the cables is known to contain abietic acid, a carboxylic acid found in many pine rosins used for the soldering process. The resulting material copper abietate is green in color and is formed during the application of heat during soldering operations. Copper (II) chloride, which is also green in color is known to contaminate flight parts and is corrosive. Data is presented that shows the material is copper abietate, not copper (II) chloride, and more importantly that the abietate does not aggressively attack nickel-plated copper wire.

  8. Reliability of Wind Turbine Components-Solder Elements Fatigue Failure

    DEFF Research Database (Denmark)

    Kostandyan, Erik; Sørensen, John Dalsgaard

    2012-01-01

    The physics of failure for electrical components due to temperature loading is described. The main focus is on crack propagation in solder joints and damage accumulation models based on the Miner’s rule. Two models are proposed that describe the initial accumulated plastic strain depending on the...... temperature mean and temperature range. Constant terms and model errors are estimated. The proposed methods are useful to predict damage values for solder joint in power electrical components. Based on the proposed methods it is described how to find the damage level for a given temperature loading profile...

  9. 基于Ag-Sn焊片共晶键合的MEMS气密性封装%Eutectic Bonding for MEMS Hermetic Packaging Based on Ag -Sn Solder Film

    Institute of Scientific and Technical Information of China (English)

    陈继超; 赵湛; 刘启民; 肖丽; 杜利东

    2012-01-01

    This paper introduced the eutectic bonding technology in MEMS hermetic packaging based on Ag - Sn solder film. The structure of multi-layer material for eutectic bonding and the pattern of sealing rings were designed. A good bonding effect was realized in the N2 protecting environment at 221 ℃,and the average shear strength was 9.4 MPa. Helium leak rate is no more than 5 × 10-4 Pa ·cm3/s in the comparative experiments through three months,which meets the GJB548B -2005 standard and verifies the feasibility of Ag - Sn eutectic bonding technology in MEMS hermetic packaging.%研究了在MEMS气密性封装中基于Ag - Sn焊片的共晶键合技术.设计了共晶键合多层材料的结构和密封环图形,在221℃实现了良好的键合效果,充N2保护的键合环境下,平均剪切强度达到9.4 Mpa.三个月前后气密性对比实验表明氦泄漏不超过5×10-4 Pa.cm3/s,满足GJB548B-2005标准规定,验证了Ag - Sn共晶键合技术在MEMS气密封装中应用的可行性.

  10. Handbook of machine soldering SMT and TH

    CERN Document Server

    Woodgate, Ralph W

    1996-01-01

    A shop-floor guide to the machine soldering of electronics Sound electrical connections are the operational backbone of every piece of electronic equipment-and the key to success in electronics manufacturing. The Handbook of Machine Soldering is dedicated to excellence in the machine soldering of electrical connections. Self-contained, comprehensive, and down-to-earth, it cuts through jargon, peels away outdated notions, and presents all the information needed to select, install, and operate machine soldering equipment. This fully updated and revised volume covers all of the new technologies and processes that have emerged in recent years, most notably the use of surface mount technology (SMT). Supplemented with 200 illustrations, this thoroughly accessible text Describes reflow and wave soldering in detail, including reflow soldering of SMT boards and the use of nitrogen blankets * Explains the setup, operation, and maintenance of a variety of soldering machines * Discusses theory, selection, and control met...

  11. Physical properties of lead free solders in liquid and solid state

    Energy Technology Data Exchange (ETDEWEB)

    Mhiaoui, Souad

    2007-04-17

    The European legislation prohibits the use of lead containing solders in Europe. However, lead free solders have a higher melting point (typical 20%) and their mechanical characteristics are worse. Additional problems are aging and adhesion of the solder on the electronic circuits. Thus, research activities must focus on the optimization of the properties of Sn-Ag-Cu based lead free solders chosen by the industry. Two main objectives are treated in this work. In the center of the first one is the study of curious hysteresis effects of metallic cadmium-antimony alloys after thermal cycles by measuring electronic transport phenomena (thermoelectric power and electrical resistivity). The second objective, within the framework of ''cotutelle'' between the universities of Metz and of Chemnitz and supported by COST531, is to study more specifically lead free solders. A welding must well conduct electricity and well conduct and dissipate heat. In Metz, we determined the electrical conductivity, the thermoelectric power and the thermal conductivity of various lead free solders (Sn-Ag-Cu, Sn-Cu, Sn-Ag, Sn-Sb) as well in the liquid as well in the solid state. The results have been compared to classical lead-tin (Pb-Sn) solders. In Chemnitz we measured the surface tension, the interfacial tension and the density of lead free solders. We also measured the viscosity of these solders without and with additives, in particular nickel. These properties were related to the industrial problems of wettability and spreadability. Lastly, we solidified alloys under various conditions. We observed undercooling. We developed a technique of mixture of nanocrystalline powder with lead free solders ''to sow'' the liquid bath in order to obtain ''different'' solids which were examined using optical and electron microscopy. (orig.)

  12. Effect of Lanthanum on Driving Force for Cu6Sn5 Growth and Improvement of Solder Joint Reliability

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    By means of adding low content of rare earth element La into Sn60-Pb40 solder alloy, the growth of Cu6Sn5 intermetallic compound at the interface of solder joint is hindered, and the thermal fatigue life of solder joint is increased by 2 times. The results of thermodynamic calculation based on diffusion kinetics show that, the driving force for Cu6Sn5 growth is lowered by adding small content of La in Sn60-Pb40 solder alloy. Meanwhile, there is an effective local mole fraction range of La, in which, 0.18% is the limited value and 0.08% is the best value.

  13. Candidate Smoke Region Segmentation of Fire Video Based on Rough Set Theory

    OpenAIRE

    Yaqin Zhao

    2015-01-01

    Candidate smoke region segmentation is the key link of smoke video detection; an effective and prompt method of candidate smoke region segmentation plays a significant role in a smoke recognition system. However, the interference of heavy fog and smoke-color moving objects greatly degrades the recognition accuracy. In this paper, a novel method of candidate smoke region segmentation based on rough set theory is presented. First, Kalman filtering is used to update video background in order to ...

  14. Lead Free Solder Joint Thermal Condition in Semiconductor Packaging

    Directory of Open Access Journals (Sweden)

    M. N. Harif

    2010-01-01

    Full Text Available Problem statement: Solder joints are responsible for both electrical and mechanical connections. Solder does not have adequate ductility to ensure the repeated relative displacements due to the mismatch between expansion coefficients of the chip carrier and the circuit board. Solder material plays a crucial role to provide the necessary electrical and mechanical interconnections in an electronic assembly. Finding a technique to increase the service life of future connections is not the total solution. A method must be developed for predicting the remaining service life of many joints already in use. Approach: The effect of High Temperature Storage (HTS on lead free solder joint material for ball grid array application using pull test method is studied in this study. Some statistical analysis base on the pull test data also discussed. Three samples of different lead free solder joint material were selected in this experiment namely Sn3.8Ag0.7Cu (SAC387, Sn2.3Ag0.08Ni0.01Co (SANC and Sn3.5Ag. After the thermal condition test, all the lead free solder joint material samples were tested using Dage 4000 pull test machine. Each pull test will be 5 units and each unit contains 8 balls. Results: The mean pull strength for high temperature storage is 2847.66, 2628.20 and 2613.79 g for Sn3.5Ag, SANC and SAC387, respectively. Thus, Sn3.5Ag shows a significantly better solder joint performance in terms of joint strength compare to SANC and SAC387. Hence, Intermetallic Compound (IMC thicknesses were measured after cross-sectioning. Sample size for cross-sectioning was 3 units per read point, 2 balls per unit and 3 maximum IMC peaks per ball and the measurement using high power scope of 100x and Image Analyzer software to measure the IMC thickness. For high temperature storage, result show that the mean IMC thicknesses for SAC387, SANC and Sn3.5Ag are 3.9139, 2.3111 and 2.3931 µm. Conclusion/Recommendations: It was found that IMC thickness for SANC and Sn3

  15. Microstructures and properties of SnZn-xEr lead-free solders

    Institute of Scientific and Technical Information of China (English)

    ZHANG Liang; CUI Junhua; HAN Jiguang; GUO Yonghuan; HE Chengwen

    2012-01-01

    The Sn9Zn eutectic alloy is the nontoxic lead-free solders alternative having a melting temperature which is closest to that of the entectic SnPb alloy.In order to improve the properties of SnZn lead-free solders,0-0.5 wt.% of rare earth Er was added to the base alloys,and the microstructures were studied.Results showed that the addition of rare earth Er could enhance the wettability of SnZn solders,with 0.08%Er addition,the spreading area gave an 19.1% increase.And based on the mechanical testing,it was found that the tensile force and shear force of SnZn-xEr solder joints could be improved significantly.Moreover,the oxidation resistance of SnZn0.08Er solder was better than that of SnZn solder.In addition,it was found that trace amounts of rare earth Er could refine the microstRUctures of SnZn solders,especially for Zn-rich phases,and excessive amount of rare earth Er led to a coarse microstructure.

  16. Characterization of solder flow on PWB surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Hosking, F.M.; Yost, F.G.

    1995-07-01

    Different solderability tests have been developed to determine the wetting behavior of solder on metallic surfaces. None offer an exact measure of capillary flow associated with conventional mixed technology soldering. With shrinking package designs, increasing reliability requirements, and the emergence of new soldering technologies, there is a growing need to better understand and predict the flow of solder on printed wiring board (PWB) surfaces. Sandia National Laboratories has developed a capillary flow solderability test, through a joint effort with the National Center for Manufacturing Sciences, that considers this fundamental wetting issue for surface mount technology. The test geometry consists of a metal strip (width, {delta}) connected to a circular metal pad (radius, r{sub c}). Test methodology, experimental results, and validation of a flow model are presented in this paper.

  17. Pilot Study of a Haptic Soldering Environment

    OpenAIRE

    Sung, R.C.W.; Ritchie, J. M.; Lim, T; Dewar, R.; Weston, N.

    2012-01-01

    Soldering plays an important role in the electronics manufacturing industry, whether it is carried out manually, semi-automatically or fully-automatically. Even though it is straightforward to learn the fundamental techniques involved in manual soldering, it still requires a vast amount of time and effort to reach an expert level. The research presented here aims to simulate the manual soldering process in a haptics environment, and by logging the users’ actions automatically and uno...

  18. A Study of Temperature, Microstructure and Hardness Properties of Sn-3.8Ag-0.7Cu (SAC Solder Alloy

    Directory of Open Access Journals (Sweden)

    Singh Amares

    2015-01-01

    Full Text Available Solder alloys are one of the most crucial aspect linking the electrical components to the printed circuit board PCB substrate. Thus, producing a good solder is a must to say in electronic industries. Among major functions of solder alloys are to provide beneficial properties in melting, microstructure and mechanical strand. In this aspect, the Sn-3.8Ag-0.7Cu (SAC solder alloys are recommended as potential candidate to assure these benefits. In this study, the solder possesses melting temperature of, TM=227°C which is below the desired soldering temperature, TM=250°C. Besides, this SAC solder produces well-defined microstructures with Sn-matrix and eutectic phase consisting Cu6Sn5 and Ag3Sn displayed from SEM image, contributes in harvesting good mechanical properties. The SAC solder also provides a high hardness value with an average of 14.4Hv for Vickers hardness. All these results seem to satisfy the need of a viable solder alloy.

  19. Simulation of thermomechanical fatigue in solder joints

    Energy Technology Data Exchange (ETDEWEB)

    Fang, H.E.; Porter, V.L.; Fye, R.M.; Holm, E.A. [Sandia National Labs., Albuquerque, NM (United States)

    1997-12-31

    Thermomechanical fatigue (TMF) is a very complex phenomenon in electronic component systems and has been identified as one prominent degradation mechanism for surface mount solder joints in the stockpile. In order to precisely predict the TMF-related effects on the reliability of electronic components in weapons, a multi-level simulation methodology is being developed at Sandia National Laboratories. This methodology links simulation codes of continuum mechanics (JAS3D), microstructural mechanics (GLAD), and microstructural evolution (PARGRAIN) to treat the disparate length scales that exist between the macroscopic response of the component and the microstructural changes occurring in its constituent materials. JAS3D is used to predict strain/temperature distributions in the component due to environmental variable fluctuations. GLAD identifies damage initiation and accumulation in detail based on the spatial information provided by JAS3D. PARGRAIN simulates the changes of material microstructure, such as the heterogeneous coarsening in Sn-Pb solder, when the component`s service environment varies.

  20. Eddy current quality control of soldered current-carrying busbar splices of superconducting magnets

    CERN Document Server

    Kogan, L; Savary, F; Principe, R; Datskov, V; Rozenfel'd, E; Khudjakov, B

    2015-01-01

    The eddy current technique associated with a U-shaped transducer is studied for the quality control of soldered joints between superconducting busbars ('splices'). Two other quality control techniques, based on X-rays and direct measurement of the electrical resistance, are also studied for comparison. A comparative analysis of the advantages and disadvantages of these three methods in relation to the quality control of soldered superconducting busbar cables enclosed in copper shells is used for benchmarking. The results of inspections with the U-shaped eddy current transducer carried out on several sample joints presenting different types of soldering defects show the potential of this type of nondestructive (ND) quality control technique.

  1. Life Prediction of Ball Grid Array Soldered Joints under Thermal Cycling Loading by Fracture Mechanics Method

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Fatigue crack propagation life of ball grid array (BGA) soldered joints during thermal cycling loading was investigated by fracture mechanics approach using finite element analysis. The relationships between the strain energy release rate (G) and crack size (α), thermal cycle numbers (N) can be derived. Based on the relationships, fatigue life of the soldered joints was determined. The results showed that crack propagation life was higher than crack initiation life. Therefore, it appears that it is more appropriate to predict the fatigue life of soldered joints using the fracture mechanics method.

  2. Lead free solder mechanics and reliability

    CERN Document Server

    Pang, John Hock Lye

    2012-01-01

    Lead-free solders are used extensively as interconnection materials in electronic assemblies and play a critical role in the global semiconductor packaging and electronics manufacturing industry. Electronic products such as smart phones, notebooks and high performance computers rely on lead-free solder joints to connect IC chip components to printed circuit boards. Lead Free Solder: Mechanics and Reliability provides in-depth design knowledge on lead-free solder elastic-plastic-creep and strain-rate dependent deformation behavior and its application in failure assessment of solder joint reliability. It includes coverage of advanced mechanics of materials theory and experiments, mechanical properties of solder and solder joint specimens, constitutive models for solder deformation behavior; numerical modeling and simulation of solder joint failure subject to thermal cycling, mechanical bending fatigue, vibration fatigue and board-level drop impact tests. This book also: Discusses the mechanical prope...

  3. A Feasibility Study of Lead Free Solders for Level 1 Packaging Applications

    DEFF Research Database (Denmark)

    Chidambaram, Vivek; Hald, John; Hattel, Jesper Henri

    2009-01-01

    An attempt has been made to determine the lead free ternary combinations that satisfied the solidification requirement for a solder used in level 1 packaging applications, using the CALPHAD approach. The segregation profiles of the promising candidates were analyzed after scrutinizing the...

  4. USING HASH BASED APRIORI ALGORITHM TO REDUCE THE CANDIDATE 2- ITEMSETS FOR MINING ASSOCIATION RULE

    OpenAIRE

    K. Vanitha

    2011-01-01

    In this paper we describe an implementation of Hash based Apriori. We analyze, theoretically and experimentally, the principal data structure of our solution. This data structure is the main factor in the efficiency of our implementation. We propose an effective hash-based algorithm for the candidate set generation. Explicitly, the number of candidate 2-itemsets generated by the proposed algorithm is, in orders of magnitude, smaller than that by previous methods, thus resolving the performanc...

  5. In-situ study of electromigration-induced grain rotation in Pb-free solder joint by synchrotron microdiffraction

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Kai; Tamura, Nobumichi; Tu, King-Ning

    2008-10-31

    The rotation of Sn grains in Pb-free flip chip solder joints hasn't been reported in literature so far although it has been observed in Sn strips. In this letter, we report the detailed study of the grain orientation evolution induced by electromigration by synchrotron based white beam X-ray microdiffraction. It is found that the grains in solder joint rotate more slowly than in Sn strip even under higher current density. On the other hand, based on our estimation, the reorientation of the grains in solder joints also results in the reduction of electric resistivity, similar to the case of Sn strip. We will also discuss the reason why the electric resistance decreases much more in strips than in the Sn-based solders, and the different driving force for the grain growth in solder joint and in thin film interconnect lines.

  6. New Candidates for Plant-Based Repellents Against Aedes aegypti.

    Science.gov (United States)

    Misni, Norashiqin; Nor, Zurainee Mohamed; Ahmad, Rohani

    2016-06-01

    Based on an ethnobotanical study on use for plant species against mosquito bites in the Kota Tinggi District, Johor State, Malaysia, 3 plants selected for study, Citrus aurantifolia (leaves), Citrus grandis (fruit peel), and Alpinia galanga (rhizome), were extracted using hydrodistillation to produce essential oils. These essential oils were then formulated as a lotion using a microencapsulation process and then tested for their repellent effect against Aedes aegypti. N,N-diethyl-m-toluamide (deet) was also prepared in the same formulation and tested for repellency as controls. Four commercial plant-based repellent (KAPS(®), MozAway(®), BioZ Natural(®), and Mosiquard(®)) also were incorporated in the bioassay for comparison purposes. Bioassays revealed that at 20% concentration all repellent formulations demonstrated complete protection for 2 h and >90% for 4 h post-application. The A. galanga-based formulation provided the greatest level of protection (98.91%), which extended for 4 h post-application and was not significantly different from deet at similar concentration. When compared with commercial plant-based repellents (KAPS(®), MozAway(®), and BioZ Natural(®)), the 3 lotion formulations showed significantly better protection against Ae. aegypti bites, providing >90% protection for 4 h. In conclusion, our 3 plant-based lotion formulations provided acceptable levels of protection against host-seeking Ae. aegypti and should be developed. PMID:27280349

  7. Effect of rare earth Ce on the fatigue life of SnAgCu solder joints in WLCSP device using FEM and experiments

    International Nuclear Information System (INIS)

    With the addition of 0.03 wt% rare earth Ce, in our previous works, the properties of SnAgCu solder were enhanced obviously. Based on the Garofalo–Arrhenius creep constitutive model, finite element method was used to simulate the stress–strain response during thermal cycle loading, and combined with the fatigue life prediction models, the fatigue life of SnAgCu/SnAgCuCe solder joints was calculated respectively, which can demonstrate the effect of the rare earth Ce on the fatigue life of SnAgCu solder joints. The results indicated that the maximum stress–strain can be found on the top surface of the corner solder joint, and the warpage of the PCB substrate occurred during thermal cycle loading. The trends obtained from modeling results have a good agreement with the experimental data reported in the literature for WLCSP devices. In addition, the stress–strain of SnAgCuCe solder joints is lower than that of SnAgCu solder joints. The thermal fatigue lives of solder joints calculated based on the creep model and creep strain energy density model show that the fatigue life of SnAgCuCe solder joints is higher than the SnAgCu solder joints. The fatigue life of SnAgCuCe solder joints can be enhanced significantly with the addition of Ce, is 30.2% higher than that of SnAgCu solder joints, which can be attributed to the CeSn3 particles formed resisting the motion of dislocation; moreover, the refinement of microstructure and the IMC sizes also contribute to the enhancement of fatigue life, which elucidates that SnAgCuCe solder can be utilized in electronic industry with high reliability replacing the SnAgCu solder

  8. Solder fused interconnections in multilayer circuits

    Energy Technology Data Exchange (ETDEWEB)

    Voida, G.

    1977-02-01

    A new solder fusion process has been developed for production of multi-layer cables and multilayer printed wiring boards. The multilayer process consists of three steps: (1) the photo-etching fabrication of the basic flexcircuit, (2) the lamination bonding of several flexcircuit layers together, and (3) solder fusion interjoining of the exposed lands to provide electrical continuity. Solder fusion is the unique feature of the process. In the solder fusion process the multilayer assembly is never in contact with highly reactive chemicals which, if entrapped, can lead to corrosion and dielectric breakdown of the assembly. Accurate layer to layer registration can be accomplished with the solder fusion process. A multilayer assembly produced by solder fusion can be shaped into three-dimensional configurations. The repeatable electrical continuity of solder fused interconnections in multilayer assemblies has been confirmed by microhm resistance testing. The solder fused multilayer assembly can be used very advantageously in highly sophisticated instruments and apparatus where portability, weight, bulk, environmental stability, and high reliability are critical requirements.

  9. Nano-soldering to single atomic layer

    Science.gov (United States)

    Girit, Caglar O.; Zettl, Alexander K.

    2011-10-11

    A simple technique to solder submicron sized, ohmic contacts to nanostructures has been disclosed. The technique has several advantages over standard electron beam lithography methods, which are complex, costly, and can contaminate samples. To demonstrate the soldering technique graphene, a single atomic layer of carbon, has been contacted, and low- and high-field electronic transport properties have been measured.

  10. Effects of voids on thermal-mechanical reliability of lead-free solder joints

    OpenAIRE

    Benabou Lahouari; Le Van Nhat; Sun Zhidan; Pougnet Philippe; Etgens Victor

    2014-01-01

    Reliability of electronic packages has become a major issue, particularly in systems used in electrical or hybrid cars where severe operating conditions must be met. Many studies have shown that solder interconnects are critical elements since many failure mechanisms originate from their typical response under thermal cycles. In this study, effects of voids in solder interconnects on the electronic assembly lifetime are estimated based on finite element simulations.

  11. Effects of voids on thermal-mechanical reliability of lead-free solder joints

    Directory of Open Access Journals (Sweden)

    Benabou Lahouari

    2014-06-01

    Full Text Available Reliability of electronic packages has become a major issue, particularly in systems used in electrical or hybrid cars where severe operating conditions must be met. Many studies have shown that solder interconnects are critical elements since many failure mechanisms originate from their typical response under thermal cycles. In this study, effects of voids in solder interconnects on the electronic assembly lifetime are estimated based on finite element simulations.

  12. Lead free soldering quality problems in electronics

    International Nuclear Information System (INIS)

    Full text: There is a growing interest in lead-free soldering in Europe mainly driven by forthcoming legislation banning the use of lead solders in electronics by July 2006. Currently the most favoured alloys (SnAgCu, SnCuNi, SnCu) to replace tin/lead solders all have 30-400 C higher melting temperature than the traditional Sn63Pb37 eutectic alloy. Therefore in general lead-free solder pastes recommend a peak temperature range 30-400 C higher as compared to Sn/Pb solder. Due to the higher reflow peak temperature the use of some materials, components, technological processes and equipment may not be feasible for Pb-free assembly. The use of new materials and higher reflow temperatures in Pb-free soldering processes causes various problems on solder joint quality and reliability. One of them is wetting behaviour. The surface tension of the lead free alloys is significantly higher than Sn/Pb therefore they wet more slowly than Sn/Pb alloys at any temperature. Critical problems, especially in the case of wave soldering, are associated with fillet lifting due to the larger temperature change during the process. Additional problem is the higher cost of lead-free soldering materials. The use of pure tin finishes as an economical lead-free plating option has the threat of failure due to tin whiskering. Methods for solder joint quality control should be modified including standard criteria formulation for visual and X-ray inspection methods as well as reliability tests should be improved

  13. Climate specific thermomechanical fatigue of flat plate photovoltaic module solder joints

    Energy Technology Data Exchange (ETDEWEB)

    Bosco, Nick; Silverman, Timothy J.; Kurtz, Sarah

    2016-07-01

    FEM simulations of PbSn solder fatigue damage are used to evaluate seven cities that represent a variety of climatic zones. It is shown that the rate of solder fatigue damage is not ranked with the cities' climate designations. For an accurate ranking, the mean maximum daily temperature, daily temperature change and a characteristic of clouding events are all required. A physics-based empirical equation is presented that accurately calculates solder fatigue damage according to these three factors. An FEM comparison of solder damage accumulated through service and thermal cycling demonstrates the number of cycles required for an equivalent exposure. For an equivalent 25-year exposure, the number of thermal cycles (-40 degrees C to 85 degrees C) required ranged from roughly 100 to 630 for the cities examined. It is demonstrated that increasing the maximum cycle temperature may significantly reduce the number of thermal cycles required for an equivalent exposure.

  14. Effect of Solder Flux Residues on Corrosion of Electronics

    DEFF Research Database (Denmark)

    Hansen, Kirsten Stentoft; Jellesen, Morten Stendahl; Møller, Per;

    2009-01-01

    Flux from ‘No Clean’ solder processes can cause reliability problems in the field due to aggressive residues, which may be electrical conducting or corrosive in humid environments. The solder temperature during a wave solder process is of great importance to the amount of residues left on a PCBA...... that no cleaning after the solder process is required. In some cases, however, this statement is not correct. Experiments with ‘No Clean’ wave solder flux have been performed, and the results show, that the solder temperature plays an important role; temperatures below 170°C cause more flux residues than solder...

  15. Inspection of the Spirometric Parameters and the Frequency of Respiratory Symptoms in Soldering Workers of a Factory Producing Electronic Appliances

    Directory of Open Access Journals (Sweden)

    E Safavi

    2005-07-01

    Full Text Available Introduction: Regarding the numerous problems of solderers in electronic industries because of their exposure to Acids, bases and fumes of soldering ,a study was carried out on107 solderers and administrative personels of a factory producing electronic appliances in Tehran to inspect the long term effects of soldering on lung functions Inspection. Methods: At first ,47 solderers and 66 controls (totally 107 persons were selected randomly. All the solderers were working in the manual soldering section and used the soldering wire made of an alloy (composed of plumbum, Stannum and special oil of soldering called flux . The persons controls worked in the administrative sections of the same factory and for the same hours as the solderers , but they did not have any soldering experience. After they filled the standard respiratory questionnaire , spirometry was done at least 3 times on each of them under the same conditions and according to the ACT criteria (No smokers included in the study Results:The spirometry parameters of the two groups were compared . There was a significant difference in the average FEF 25 : 75% (P=0.03.Also ,there was a significant difference in the average FEV1/FVC P=0.026 and PEFR (P=0.04between two groups .After controling the altering age factor . ameaningful relation between the years of work in soldering section and decrease in the spirometry parameters related to FED 25-75% and FEV1/FVC was seem . Also . the frequency of the signs of nasal and eyes initation in the solderer group was more than the other group (p=0.007 Cough and Asthma related to ork had no meaningful difference in the two groups . Conclsion :It seem that in the above study , soldering is a factor decreasing the spirometry parameters with a blocking pattern , especilly in smal airways . This study was done in the direction of the former studies done in other countries and emphasizes on the need for necessary preventive action in this profession , uch as

  16. Joint Lead-Free Solder Test Program for High Reliability Military and Space Applications

    Science.gov (United States)

    Brown, Christina

    2004-01-01

    Current and future space and defense systems face potential risks from the continued use of tin-lead solder, including: compliance with current environmental regulations, concerns about potential environmental legislation banning lead-containing products, reduced mission readiness, and component obsolescence with lead surface finishes. For example, the United States Environmental Protection Agency (USEPA) has lowered the Toxic Chemical Release reporting threshold for lead to 100 pounds. Overseas, the Waste Electrical and Electronic Equipment (WEEE) and the Restriction on Hazardous Substances (RoHS) Dicctives in Europe and similar mandates in Japan have instilled concern that a legislative body will prohibit the use of lead in aerospace/military electronics soldering. Any potential banning of lead compounds could reduce the supplier base and adversely affect the readiness of missions led by the National Aeronautics and Space Administration (NASA) and the U.S. Department of Defense (DoD). Before considering lead-free electronics for system upgrades or future designs, however, it is important for the DoD and NASA to know whether lead-free solders can meet their systems' requirements. No single lead-free solder is likely to qualify for all defense and space applications. Therefore, it is important to validate alternative solders for discrete applications. As a result of the need for comprehensive test data on the reliability of lead-free solders, a partnership was formed between the DoD, NASA, and several original equipment manufactures (OEMs) to conduct solder-joint reliability (laboratory) testing of three lead-free solder alloys on newly manufactured and reworked circuit cards to generate performance data for high-reliability (IPC Class 3) applications.

  17. Solderability of melting lead-free solder to tiny joint of electronic products

    Science.gov (United States)

    Chen, Fang; Du, Changhua; Du, Yunfei

    2005-12-01

    The behavior of melting solder has an important influence on the tiny joints of electronic products. In order to improve the properties of lead-free solder, a Sn-3.5Ag0.6Cu alloy was smelted using traditional and a modified technology, respectively. The solderability of the two alloys were investigated using a wetting balance method for the different conditions. The test results showed that the modified solder had good solderability, where the excellent flux used was rosin-ethanol or rosin-isopropanol solution. In experimental condition, when the added active agent is 0.4% of rosin mass or 0.1% of solution mass, the wetting velocity and wetting force can be improved 5 times and 1.5 times, respectively. The best soldering parameters are temperature levels less than or equal to 270°, and the soakage time in 2-3s.

  18. A Novel Technique for the Connection of Ceramic and Titanium Implant Components Using Glass Solder Bonding

    Directory of Open Access Journals (Sweden)

    Enrico Mick

    2015-07-01

    Full Text Available Both titanium and ceramic materials provide specific advantages in dental implant technology. However, some problems, like hypersensitivity reactions, corrosion and mechanical failure, have been reported. Therefore, the combining of both materials to take advantage of their pros, while eliminating their respective cons, would be desirable. Hence, we introduced a new technique to bond titanium and ceramic materials by means of a silica-based glass ceramic solder. Cylindrical compound samples (Ø10 mm × 56 mm made of alumina toughened zirconia (ATZ, as well as titanium grade 5, were bonded by glass solder on their end faces. As a control, a two-component adhesive glue was utilized. The samples were investigated without further treatment, after 30 and 90 days of storage in distilled water at room temperature, and after aging. All samples were subjected to quasi-static four-point-bending tests. We found that the glass solder bonding provided significantly higher bending strength than adhesive glue bonding. In contrast to the glued samples, the bending strength of the soldered samples remained unaltered by the storage and aging treatments. Scanning electron microscopy (SEM and energy-dispersive X-ray (EDX analyses confirmed the presence of a stable solder-ceramic interface. Therefore, the glass solder technique represents a promising method for optimizing dental and orthopedic implant bondings.

  19. Differentially Private Frequent Sequence Mining via Sampling-based Candidate Pruning

    Science.gov (United States)

    Xu, Shengzhi; Cheng, Xiang; Li, Zhengyi; Xiong, Li

    2016-01-01

    In this paper, we study the problem of mining frequent sequences under the rigorous differential privacy model. We explore the possibility of designing a differentially private frequent sequence mining (FSM) algorithm which can achieve both high data utility and a high degree of privacy. We found, in differentially private FSM, the amount of required noise is proportionate to the number of candidate sequences. If we could effectively reduce the number of unpromising candidate sequences, the utility and privacy tradeoff can be significantly improved. To this end, by leveraging a sampling-based candidate pruning technique, we propose a novel differentially private FSM algorithm, which is referred to as PFS2. The core of our algorithm is to utilize sample databases to further prune the candidate sequences generated based on the downward closure property. In particular, we use the noisy local support of candidate sequences in the sample databases to estimate which sequences are potentially frequent. To improve the accuracy of such private estimations, a sequence shrinking method is proposed to enforce the length constraint on the sample databases. Moreover, to decrease the probability of misestimating frequent sequences as infrequent, a threshold relaxation method is proposed to relax the user-specified threshold for the sample databases. Through formal privacy analysis, we show that our PFS2 algorithm is ε-differentially private. Extensive experiments on real datasets illustrate that our PFS2 algorithm can privately find frequent sequences with high accuracy. PMID:26973430

  20. Induction soldering of photovoltaic system components

    Science.gov (United States)

    Kumaria, Shashwat; de Leon, Briccio

    2015-11-17

    A method comprises positioning a pair of photovoltaic wafers in a side-by-side arrangement. An interconnect is placed on the pair of wafers such that the interconnect overlaps both wafers of the pair, solder material being provided between the interconnect and the respective wafers. A solder head is then located adjacent the interconnect, and the coil is energized to effect inductive heating of the solder material. The solder head comprises an induction coil shaped to define an eye, and a magnetic field concentrator located at least partially in the eye of the coil. The magnetic field concentrator defines a passage extending axially through the eye of the coil, and may be of a material with a high magnetic permeability.

  1. Calibration of the Gaia RVS from ground-based observations of candidate standard stars

    OpenAIRE

    Chemin, L.; Soubiran, C.; Crifo, Françoise; Jasniewicz, Gérard; Katz, David; Hestroffer, Daniel; Udry, Stéphane

    2011-01-01

    International audience The Radial Velocity Spectrometer (RVS) on board of Gaia will perform a large spectroscopic survey to determine the radial velocities of some 1.5 × 10^8 stars. We present the status of ground-based observations of a sample of 1420 candidate standard stars designed to calibrate the RVS. Each candidate star has to be observed several times before Gaia launch (and at least once during the mission) to ensure that its radial velocity remains stable during the whole mission...

  2. Calibration of the Gaia Radial Velocity Spectrometer from ground-based observations of candidate standard stars

    OpenAIRE

    Chemin, L.; Soubiran, C.; Crifo, F.; Jasniewicz, G.; Katz, D.; Hestroffer, D.; Udry, S.

    2011-01-01

    The Radial Velocity Spectrometer (RVS) on board of Gaia will perform a large spectroscopic survey to determine the radial velocities of some 1.5x10^8 stars. We present the status of ground-based observations of a sample of 1420 candidate standard stars designed to calibrate the RVS. Each candidate star has to be observed several times before Gaia launch (and at least once during the mission) to ensure that its radial velocity remains stable during the whole mission. Observations are performed...

  3. A three-dimensional measurement method based on mesh candidates assisted with structured light

    Science.gov (United States)

    Xu, Gang; Zhang, Wenming; Li, Haibin; Liu, Bin

    2009-07-01

    Rendering three-dimensional information of a scene from optical measurement is very important for a wide variety of applications such as robot navigation, rapid prototyping, medical imaging, industrial inspection, etc. In this paper, a new 3D measurement method based on mesh candidate with structured light illuminating is proposed. The vision sensor consists of two CCD cameras and a DLP projector. The measurement system combines the technology of binocular stereo vision and structured light, so as to simplify the process of acquiring depth information using mesh candidates. The measurement method is based on mesh candidates which represent the potential depth in the three dimensional scene. First the mesh grid was created along the direction of axes in world coordinate system, and the nodes were considered as depth candidates on the surface of object. Then each group of the mesh nodes varying along z axis were mapped to the captured image planes of both cameras. At last, according to the similarity measure of the corresponding pixel pairs, the depth of the object surface can be obtained. The matching process is between the pixels in both camera planes corresponding to the spatial mesh candidates. Aided by the structured light pattern, the accuracy of measurement system improved. Appending the periodic sawtooth pattern on the scene by structured light made measurement easier, while the computational cost did not increased since the projector had no need to be calibrated. The 3DS MAX and Matlab software were used to simulate measurement system and reconstruct the surface of the object. After the positioned cameras have been calibrated using Matlab calibration toolbox, the projector is used to project structured light pattern on the scene. Indicated by experimental results, the mesh-candidate-based method is obviously superior in computation and accuracy. Compared with traditional methods based on image matching, our method has several advantages: (1) the complex

  4. A Plant-Based Transient Expression System for the Rapid Production of Malaria Vaccine Candidates.

    Science.gov (United States)

    Boes, Alexander; Reimann, Andreas; Twyman, Richard M; Fischer, Rainer; Schillberg, Stefan; Spiegel, Holger

    2016-01-01

    There are currently no vaccines that provide sterile immunity against malaria. Various proteins from different stages of the Plasmodium falciparum life cycle have been evaluated as vaccine candidates, but none of them have fulfilled expectations. Therefore, combinations of key antigens from different stages of the parasites life cycle may be essential for the development of efficacious malaria vaccines. Following the identification of promising antigens using bioinformatics, proteomics, and/or immunological approaches, it is necessary to express, purify, and characterize these proteins and explore the potential of fusion constructs combining different antigens or antigen domains before committing to expensive and time-consuming clinical development. Here, using malaria vaccine candidates as an example, we describe how Agrobacterium tumefaciens-based transient expression in plants can be combined with a modular and flexible cloning strategy as a robust and versatile tool for the rapid production of candidate antigens during research and development. PMID:27076325

  5. Whisker Formation on SAC305 Soldered Assemblies

    Science.gov (United States)

    Meschter, S.; Snugovsky, P.; Bagheri, Z.; Kosiba, E.; Romansky, M.; Kennedy, J.; Snugovsky, L.; Perovic, D.

    2014-11-01

    This article describes the results of a whisker formation study on SAC305 assemblies, evaluating the effects of lead-frame materials and cleanliness in different environments: low-stress simulated power cycling (50-85°C thermal cycling), thermal shock (-55°C to 85°C), and high temperature/high humidity (85°C/85% RH). Cleaned and contaminated small outline transistors, large leaded quad flat packs (QFP), plastic leaded chip carrier packages, and solder balls with and without rare earth elements (REE) were soldered to custom designed test boards with Sn3Ag0.5Cu (SAC305) solder. After assembly, all the boards were cleaned, and half of them were recontaminated (1.56 µg/cm2 Cl-). Whisker length, diameter, and density were measured. Detailed metallurgical analysis on components before assembly and on solder joints before and after testing was performed. It was found that whiskers grow from solder joint fillets, where the thickness is less than 25 µm, unless REE was present. The influence of lead-frame and solder ball material, microstructure, cleanliness, and environment on whisker characteristics is discussed. This article provides detailed metallurgical observations and select whisker length data obtained during this multiyear testing program.

  6. Comparison of Extensive Thermal Cycling Effects on Microstructure Development in Micro-alloyed Sn-Ag-Cu Solder Joints

    Energy Technology Data Exchange (ETDEWEB)

    Anderson, Iver E.; Boesenberg, Adam; Harringa, Joel; Riegner, David; Steinmetz, Andrew; Hillman, David

    2011-09-28

    Pb-free solder alloys based on the Sn-Ag-Cu (SAC) ternary eutectic have promise for widespread adoption across assembly conditions and operating environments, but enhanced microstructural control is needed. Micro-alloying with elements such as Zn was demonstrated for promoting a preferred solidification path and joint microstructure earlier in simple (Cu/Cu) solder joints studies for different cooling rates. This beneficial behavior now has been verified in reworked ball grid array (BGA) joints, using dissimilar SAC305 (Sn-3.0Ag-0.5Cu, wt.%) solder paste. After industrial assembly, BGA components joined with Sn-3.5Ag-0.74Cu-0.21Zn solder were tested in thermal cycling (-55 C/+125 C) along with baseline SAC305 BGA joints beyond 3000 cycles with continuous failure monitoring. Weibull analysis of the results demonstrated that BGA components joined with SAC + Zn/SAC305 have less joint integrity than SAC305 joints, but their lifetime is sufficient for severe applications in consumer, defense, and avionics electronic product field environments. Failure analysis of the BGA joints revealed that cracking did not deviate from the typical top area (BGA component side) of each joint, in spite of different Ag3Sn blade content. Thus, SAC + Zn solder has not shown any advantage over SAC305 solder in these thermal cycling trials, but other characteristics of SAC + Zn solder may make it more attractive for use across the full range of harsh conditions of avionics or defense applications.

  7. Experimental characterization of the mechanical behavior of two solder alloys for high temperature power electronics applications

    OpenAIRE

    Msolli, Sabeur; Alexis, Joël; Dalverny, Olivier; Karama, Moussa

    2015-01-01

    An experimental investigation of two potential candidate materials for the diamond die attachment is presented in this framework. These efforts are motivated by the need of developing a power electronic packaging for the diamond chip. The performance of the designed packaging relies particularly on the specific choice of the solder alloys for the die/substrate junction. To implement a high temperature junction, AuGe and AlSi eutectic alloys were chosen as die attachment and characterized expe...

  8. Age-aware solder performance models : level 2 milestone completion.

    Energy Technology Data Exchange (ETDEWEB)

    Neilsen, Michael K.; Vianco, Paul Thomas; Neidigk, Matthew Aaron; Holm, Elizabeth Ann

    2010-09-01

    Legislated requirements and industry standards are replacing eutectic lead-tin (Pb-Sn) solders with lead-free (Pb-free) solders in future component designs and in replacements and retrofits. Since Pb-free solders have not yet seen service for long periods, their long-term behavior is poorly characterized. Because understanding the reliability of Pb-free solders is critical to supporting the next generation of circuit board designs, it is imperative that we develop, validate and exercise a solder lifetime model that can capture the thermomechanical response of Pb-free solder joints in stockpile components. To this end, an ASC Level 2 milestone was identified for fiscal year 2010: Milestone 3605: Utilize experimentally validated constitutive model for lead-free solder to simulate aging and reliability of solder joints in stockpile components. This report documents the completion of this milestone, including evidence that the milestone completion criteria were met and a summary of the milestone Program Review.

  9. An Evaluation Method for Tensile Characteristics of Cu/Sn IMCs Using Miniature Composite Solder Specimen

    Science.gov (United States)

    Ohguchi, Ken-ichi; Kurosawa, Kengo

    2016-06-01

    In design of electronic packages, finite-element method (FEM) analysis for evaluating the strength and reliability of solder joints should be conducted with consideration of the presence of Cu/Sn intermetallic compounds (IMCs) generated at the interface between solder and copper wiring. To conduct such analysis accurately, the deformation characteristics of Cu/Sn IMCs must be clarified by conducting tensile tests. This paper describes a method to evaluate tensile characteristics of Cu/Sn IMCs. The method employs a composite specimen with first outer layer of Cu, second layer of Cu/Sn IMCs, and core of Sn-3.0Ag-0.5Cu lead-free solder. The specimen is made by a method in which a copper-plated solder specimen is heat treated at 453 K to generate Cu/Sn IMCs between the solder and copper. Tensile tests were conducted using the composite specimen. After the tests, the fracture appearance and characteristics of the stress-strain relations of the specimens were investigated. Based on the results, a numerical method based on the rule of mixtures (ROM) is proposed to estimate the stress-strain relation of Cu/Sn IMCs under tensile loading.

  10. Effect of Preconditioning and Soldering on Failures of Chip Tantalum Capacitors

    Science.gov (United States)

    Teverovsky, Alexander A.

    2014-01-01

    Soldering of molded case tantalum capacitors can result in damage to Ta205 dielectric and first turn-on failures due to thermo-mechanical stresses caused by CTE mismatch between materials used in the capacitors. It is also known that presence of moisture might cause damage to plastic cases due to the pop-corning effect. However, there are only scarce literature data on the effect of moisture content on the probability of post-soldering electrical failures. In this work, that is based on a case history, different groups of similar types of CWR tantalum capacitors from two lots were prepared for soldering by bake, moisture saturation, and longterm storage at room conditions. Results of the testing showed that both factors: initial quality of the lot, and preconditioning affect the probability of failures. Baking before soldering was shown to be effective to prevent failures even in lots susceptible to pop-corning damage. Mechanism of failures is discussed and recommendations for pre-soldering bake are suggested based on analysis of moisture characteristics of materials used in the capacitors' design.

  11. Single-wall carbon nanotube (SWCNT) functionalized Sn-Ag-Cu lead-free composite solders

    International Nuclear Information System (INIS)

    Sn-3.8Ag-0.7Cu-based composite solders functionalized with single-wall carbon nanotubes (SWCNTs) with various weight proportions ranging from 0.01 to 1 wt% were successfully produced. The microstuctural, melting and mechanical properties of Sn-3.8Ag-0.7Cu-based composite solders were evaluated as a function of different wt% of SWCNT addition. The microstructures of the composite specimens were studied by means of field-emission scanning electron microscope (FE-SEM). It was observed that SWCNTs were homogeneously distributed at the edges of Ag3Sn compounds that are distributed evenly in the β-Sn solder matrix. Energy dispersion X-ray (EDX) analysis method was employed to reveal the presence of the phases existed in the solder composites. The mechanical properties of the composite solders were evaluated by Vickers-microhardness measurements and tensile tests performed at room temperature. The different wt% and addition of SWCNTs to Sn-3.8Ag-0.7Cu produced a dramatic increase in tensile strength, hardness, and better melting characteristics. A slight decrease in elongation to failure was observed. FE-SEM observations of the fracture surface, revealed the overall failure mechanism as the ductile manner of failure

  12. Fundamentals of lead-free solder interconnect technology from microstructures to reliability

    CERN Document Server

    Lee, Tae-Kyu; Kim, Choong-Un; Ma, Hongtao

    2015-01-01

    This unique book provides an up-to-date overview of the fundamental concepts behind lead-free solder and interconnection technology. Readers will find a description of the rapidly increasing presence of electronic systems in all aspects of modern life as well as the increasing need for predictable reliability in electronic systems. The physical and mechanical properties of lead-free solders are examined in detail, and building on fundamental science, the mechanisms responsible for damage and failure evolution, which affect reliability of lead-free solder joints are identified based on microstructure evolution.  The continuing miniaturization of electronic systems will increase the demand on the performance of solder joints, which will require new alloy and processing strategies as well as interconnection design strategies. This book provides a foundation on which improved performance and new design approaches can be based.  In summary, this book:  Provides an up-to-date overview on lead-free soldering tech...

  13. Efforts to Develop a 300°C Solder

    Energy Technology Data Exchange (ETDEWEB)

    Norann, Randy A [Perma Works LLC

    2015-01-25

    This paper covers the efforts made to find a 300°C electrical solder solution for geothermal well monitoring and logging tools by Perma Works LLC. This paper covers: why a high temperature solder is needed, what makes for a good solder, testing flux, testing conductive epoxy and testing intermetallic bonds. Future areas of research are suggested.

  14. Microstructural evolution of eutectic Au-Sn solder joints

    Energy Technology Data Exchange (ETDEWEB)

    Song, Ho Geon

    2002-05-31

    Current trends toward miniaturization and the use of lead(Pb)-free solder in electronic packaging present new problems in the reliability of solder joints. This study was performed in order to understand the microstructure and microstructural evolution of small volumes of nominally eutectic Au-Sn solder joints (80Au-20Sn by weight), which gives insight into properties and reliability.

  15. Microstructural evolution of eutectic Au-Sn solder joints

    OpenAIRE

    Song, Ho Geon

    2002-01-01

    Current trends toward miniaturization and the use of lead(Pb)-free solder in electronic packaging present new problems in the reliability of solder joints. This study was performed in order to understand the microstructure and microstructural evolution of small volumes of nominally eutectic Au-Sn solder joints (80Au-20Sn by weight), which gives insight into properties and reliability.

  16. Effect of Solder Flux Residues on Corrosion of Electronics

    DEFF Research Database (Denmark)

    Hansen, Kirsten Stentoft; Jellesen, Morten Stendahl; Møller, Per; Westermann, Peter Jacob Schwencke; Ambat, Rajan

    2009-01-01

    Flux from ‘No Clean’ solder processes can cause reliability problems in the field due to aggressive residues, which may be electrical conducting or corrosive in humid environments. The solder temperature during a wave solder process is of great importance to the amount of residues left on a PCBA...

  17. A novel method for direct solder bump pull testing using lead-free solders

    Science.gov (United States)

    Turner, Gregory Alan

    This thesis focuses on the design, fabrication, and evaluation of a new method for testing the adhesion strength of lead-free solders, named the Isotraction Bump Pull method (IBP). In order to develop a direct solder joint-strength testing method that did not require customization for different solder types, bump sizes, specific equipment, or trial-and-error, a combination of two widely used and accepted standards was created. First, solder bumps were made from three types of lead free solder were generated on untreated copper PCB substrates using an in-house fabricated solder bump-on-demand generator, Following this, the newly developed method made use of a polymer epoxy to encapsulate the solder bumps that could then be tested under tension using a high precision universal vertical load machine. The tests produced repeatable and predictable results for each of the three alloys tested that were in agreement with the relative behavior of the same alloys using other testing methods in the literature. The median peak stress at failure for the three solders tested were 2020.52 psi, 940.57 psi, and 2781.0 psi, and were within one standard deviation of the of all data collected for each solder. The assumptions in this work that brittle fracture occurred through the Intermetallic Compound layer (IMC) were validated with the use of Energy-Dispersive X-Ray Spectrometry and high magnification of the fractured surface of both newly exposed sides of the test specimens. Following this, an examination of the process to apply the results from the tensile tests into standard material science equations for the fracture of the systems was performed..

  18. Microstructure and In Situ Observations of Undercooling for Nucleation of β-Sn Relevant to Lead-Free Solder Alloys

    OpenAIRE

    Elmer, John W.; Specht, Eliot D.; Kumar, Mukul

    2010-01-01

    Difficult nucleation of β-Sn during solidification of tin and tin-based lead-free solder alloys can result in high degrees of undercooling of the liquid prior to solidification. The undercooling can produce solder joints with large grains, anisotropic behavior, and undesirable mechanical properties. This paper describes our examination of the amount of undercooling of tin on both graphite (non-wetting) and copper (wetting) surfaces using in situ x-ray diffraction. The microstructure was furth...

  19. Physics of Failure as a Basis for Solder Elements Reliability Assessment in Wind Turbines

    DEFF Research Database (Denmark)

    Kostandyan, Erik; Sørensen, John Dalsgaard

    Traditionally assessment of reliability of electrical components is done by classical reliability techniques using failure rates as the basic measure of reliability. In this paper a structural reliability approach is applied in order to include all relevant uncertainties and to give a more detailed...... description of the reliability. A physics of failure approach is applied. A SnAg solder component used in power electronics is used as an example. Crack propagation in the SnAg solder is modeled and a model to assess the accumulated plastic strain is proposed based on a physics of failure approach. Based on...

  20. Capillary wave formation on excited solder jet and fabrication of lead-free solder ball

    Institute of Scientific and Technical Information of China (English)

    ZHANG Shu-guang; HE Li-jun; ZHU Xue-xin; ZHANG Shao-ming; SHI Li-kai; XU Jun

    2005-01-01

    A survey of solder ball production processes especially focusing on disturbed molten metal jet breakup process was made. Then the formation of capillary wave on tin melt jet in the way of rapid solidification was studied. A semi-empirical formula, which can be written as λ = Cvib (σ/ρ)1/3f-2/3 to predict the relationship between wavelength of capillary wave and frequency of imposed vibration was obtained. Sn-4.0Ag-0.5Cu lead free solder ball was successfully produced with tight distribution and good sphericity. The excited jet breakup process is promising for cost effectively producing solder ball.

  1. Intelligent laser soldering inspection and process control

    Science.gov (United States)

    Vanzetti, Riccardo

    1987-01-01

    Component assembly on printed circuitry keeps making giant strides toward denser packaging and smaller dimensions. From a single layer to multilayer, from through holes to surface mounted components and tape applied bonds, unrelenting progress results in new, difficult problems in assembling, soldering, inspecting and controlling the manufacturing process of the new electronics. Among the major problems are the variables introduced by human operators. The small dimensions and the tight assembly tolerances are now successfully met by machines which are faster and more precise than the human hand. The same is true for soldering. But visual inspection of the solder joints is now so severely limited by the ever shrinking area accessible to the human eye that the inspector's diagnosis cannot be trusted any longer. Solutions to correcting these problems are discussed.

  2. ESD Test Apparatus for Soldering Irons

    Science.gov (United States)

    Sancho, Jose; Esser, Robert

    2013-01-01

    ESDA (Electrostatic Discharge Association) ESD STM 13.1-2000 requires frequent testing of the voltage leakage from the tip of a soldering iron and the resistance from the tip of the soldering iron to the common point ground. Without this test apparatus, the process is time-consuming and requires several wires, alligator clips, or test probes, as well as additional equipment. Soldering iron tips must be tested for electrostatic discharge risks frequently, and this typically takes a lot of time in setup and testing. This device enables the operator to execute the full test in one minute or less. This innovation is a simple apparatus that plugs into a digital multimeter (DMM) and the Common Point Ground (CPG) reference. It enables the user to perform two of the electrostatic discharge tests required in ESD STM 13.1-2000. The device consists of a small black box with two prongs sticking out of one end, two inputs on the opposite end (one of the inputs is used to connect the reference CPG to the DMM), and a metal tab on one side. Inside the box are wires, several washers of various materials, and assembly hardware (nuts and screws/bolts). The device is a passive electronic component that is plugged into a DMM. The operator sets the DMM to read voltage. The operator places the heated tip of the soldering iron onto the metal tab with a small amount of solder to ensure a complete connection. The voltage is read and recorded. The operator switches the DMM to read resistance. The operator places the heated tip of the soldering iron onto the metal tab with a small amount of solder to ensure a complete connection. The resistance is recorded. If the recorded voltage and resistance are below a number stated in ESDA ESD STM 13.1-2000, the test is considered to pass. The device includes all the necessary wiring internal to its body so the operator does not need to do any independent wiring, except for grounding. It uses a stack of high-thermal-resistance washers to minimize the

  3. Lead (Pb)-Free Solder Applications

    Energy Technology Data Exchange (ETDEWEB)

    VIANCO,PAUL T.

    2000-08-15

    Legislative and marketing forces both abroad and in the US are causing the electronics industry to consider the use of Pb-free solders in place of traditional Sn-Pb alloys. Previous case studies have demonstrated the satisfactory manufacturability and reliability of several Pb-free compositions for printed circuit board applications. Those data, together with the results of fundamental studies on Pb-free solder materials, have indicated the general feasibility of their use in the broader range of present-day, electrical and electronic components.

  4. Candidate Smoke Region Segmentation of Fire Video Based on Rough Set Theory

    Directory of Open Access Journals (Sweden)

    Yaqin Zhao

    2015-01-01

    Full Text Available Candidate smoke region segmentation is the key link of smoke video detection; an effective and prompt method of candidate smoke region segmentation plays a significant role in a smoke recognition system. However, the interference of heavy fog and smoke-color moving objects greatly degrades the recognition accuracy. In this paper, a novel method of candidate smoke region segmentation based on rough set theory is presented. First, Kalman filtering is used to update video background in order to exclude the interference of static smoke-color objects, such as blue sky. Second, in RGB color space smoke regions are segmented by defining the upper approximation, lower approximation, and roughness of smoke-color distribution. Finally, in HSV color space small smoke regions are merged by the definition of equivalence relation so as to distinguish smoke images from heavy fog images in terms of V component value variety from center to edge of smoke region. The experimental results on smoke region segmentation demonstrated the effectiveness and usefulness of the proposed scheme.

  5. Commentary: Photothermal effects of laser tissue soldering

    International Nuclear Information System (INIS)

    freezing and thawing induces extracellular and intracellular damage. The study is methodologically sound, and the findings in agreement with those of previous studies, i.e. increasing the concentration of the solder results in a greater tensile strength of the bonded tissue and the higher the tissue temperature the greater the thermal damage. As proteins are believed to be the primary component of the welding process, topical applied proteins, used as solders, may provide the necessary amount of protein for welding and result in a greater tensile strength (Poppas et al 1992). A surprising finding is that no colour changes were observed at the irradiances producing optimal tensile strength (corresponding to a temperature of 85 deg. C), as it is above the denaturisation temperature of proteins and logically would be expected to result in some colour changes. Availability and cost are the biggest obstacles to the widespread use of lasers in tissue welding. Most lasers are not equipped with a stable milliwatt mode and/or a micromanipulator. Sutures, on the contrary, are cheap, reliable and always readily available. From a technical point of view, elements of the laser welding technique are unfamiliar to most surgeons. Therefore, acquisition of technical skills and handling of the laser is essential in a laboratory set-up before proceeding to the clinic. For repair of tissues in humans, placement of sutures seems to be mandatory to facilitate manipulation of the tissue during laser irradiation and to lower the risk of post-operative dehiscence. To use the laser only to avoid the placement of extra sutures (and thus proceeding to standard suture repair) seems, at present, unjustified as many studies have failed to show significant results in favour of laser welding. The end point in tissue welding is, at the moment, based on visual changes of the tissue and the surgeon must 'see and feel' whether the welding is complete. It is important that many investigations continue in the

  6. Single Image Camera Calibration in Close Range Photogrammetry for Solder Joint Analysis

    Science.gov (United States)

    Heinemann, D.; Knabner, S.; Baumgarten, D.

    2016-06-01

    Printed Circuit Boards (PCB) play an important role in the manufacturing of electronic devices. To ensure a correct function of the PCBs a certain amount of solder paste is needed during the placement of components. The aim of the current research is to develop an real-time, closed-loop solution for the analysis of the printing process where solder is printed onto PCBs. Close range photogrammetry allows for determination of the solder volume and a subsequent correction if necessary. Photogrammetry is an image based method for three dimensional reconstruction from two dimensional image data of an object. A precise camera calibration is indispensable for an accurate reconstruction. In our certain application it is not possible to use calibration methods with two dimensional calibration targets. Therefore a special calibration target was developed and manufactured, which allows for single image camera calibration.

  7. Effects of PCB thickness on adjustable fountain wave soldering

    Indian Academy of Sciences (India)

    M S Abdul Aziz; M Z Abdullah; C Y Khor; A Jalar; M A Bakar; W Y W Yusoff; F Che Ani; Nobe Yan; M Zhou; C Cheok

    2015-10-01

    This study investigates the effects of printed circuit board (PCB) thickness on adjustable fountain and conventional wave soldering. The pin-through-hole (PTH) vertical fill is examined with three PCBs of different thicknesses (i.e., 1.6, 3.1, and 6.0 mm) soldered through adjustable fountain and conventional wave soldering at conveyor angles of 0° and 6°. The vertical fill of each PCB is the focus. The PTH solder profile is inspected with a non-destructive X-ray computed tomography scanning machine. The percentages of the PTH vertical fill of both soldering processes are also estimated and compared. The aspect ratio of the PCB is also investigated. Experimental results reveal that adjustable fountain wave soldering yields better vertical fill than conventional wave soldering. The vertical fill level of adjustable fountain wave soldering is 100%, 90%, and 50% for the 1.6, 3.1, and 6.0 mm PCB thickness, respectively. FLUENT simulation is conducted for the vertical fill of the solder profile. Simulation and experimental results show that the PTH solder profiles of the two soldering processes are almost identical. The effect of PCB thickness on PTH voiding is also discussed.

  8. Effect of trace elements on the interface reactions between two lead-free solders and copper or nickel substrates

    Directory of Open Access Journals (Sweden)

    Soares D.

    2007-01-01

    Full Text Available Traditional Sn-Pb solder alloys are being replaced, because of environmental and health concerns about lead toxicity. Among some alternative alloy systems, the Sn-Zn and Sn-Cu base alloy systems have been studied and reveal promising properties. The reliability of a solder joint is affected by the solder/substrate interaction and the nature of the layers formed at the interface. The solder/substrate reactions, for Sn-Zn and Sn-Cu base solder alloys, were evaluated in what concerns the morphology and chemical composition of the interface layers. The effect of the addition of P, at low levels, on the chemical composition of the layers present at the interface was studied. The phases formed at the interface between the Cu or Ni substrate and a molten lead-free solder at 250ºC, were studied for different stage times and alloy compositions. The melting temperatures, of the studied alloys, were determined by Differential Scanning Calorimetry (DSC. Identification of equilibrium phases formed at the interface layer, and the evaluation of their chemical composition were performed by Scanning Electron Microscopy (SEM/EDS. Different interface characteristics were obtained, namely for the alloys containing Zn. The obtained IML layer thickness was compared, for both types of alloy systems.

  9. Solder for oxide layer-building metals and alloys

    International Nuclear Information System (INIS)

    A low temperature solder and method for soldering an oxide layer-building metal such as aluminum, titanium, tantalum or stainless steel is disclosed. The composition comprises tin and zinc; germanium as a wetting agent; preferably small amounts of copper and antimony; and a grit, such as silicon carbide. The grit abrades any oxide layer formed on the surface of the metal as the germanium penetrates beneath and loosens the oxide layer to provide good metal-to-metal contact. The germanium comprises less than approximately 10% by weight of the solder composition so that it provides sufficient wetting action but does not result in a melting temperature above approximately 300 C. The method comprises the steps rubbing the solder against the metal surface so the grit in the solder abrades the surface while heating the surface until the solder begins to melt and the germanium penetrates the oxide layer, then brushing aside any oxide layer loosened by the solder

  10. Finite element simulation for mechanical response of surface mounted solder joints under different temperature cycling

    Institute of Scientific and Technical Information of China (English)

    马鑫; 钱乙余

    2001-01-01

    Nonlinear finite element simulation for mechanical response of surface mounted solder joint under different temperature cycling was carried out. Seven sets of parameters were used in order to evaluate the influence of temperature cycling profile parameters. The results show that temperature cycling history has significant effect on the stress response of the solder joint. Based on the concept of relative damage stress proposed by the authors, it is found that enough high temperature holding time is necessary for designing the temperature cycling profile in accelerated thermal fatigue test.

  11. Tin-silver-bismuth solders for electronics assembly

    Science.gov (United States)

    Vianco, Paul T.; Rejent, Jerome A.

    1995-01-01

    A lead-free solder alloy for electronic assemblies composed of a eutectic alloy of tin and silver with a bismuth addition, x, of 0tin effective to depress the melting point of the tin-silver composition to a desired level. Melting point ranges from about 218.degree. C. down to about 205.degree. C. depending an the amount of bismuth added to the eutectic tin-silver alloy as determined by DSC analysis, 10.degree. C./min. A preferred alloy composition is 91.84Sn-3.33Ag-4.83Bi (weight percent based on total alloy weight).

  12. Influence of nickel–phosphorus surface roughness on wettability and pores formation in solder joints for high power electronic applications

    Energy Technology Data Exchange (ETDEWEB)

    Vivet, L., E-mail: laurent.vivet@valeo.com [Valeo, Group Electronic Expertise and Development Services, 2 rue André Boulle, 94046 Créteil (France); Joudrier, A.-L. [Institut Lavoisier de Versailles, UMR CNRS 8180, 45 Avenue des Etats-Unis, 78035 Versailles (France); Tan, K.-L.; Morelle, J.-M. [Valeo, Group Electronic Expertise and Development Services, 2 rue André Boulle, 94046 Créteil (France); Etcheberry, A. [Institut Lavoisier de Versailles, UMR CNRS 8180, 45 Avenue des Etats-Unis, 78035 Versailles (France); Chalumeau, L. [Egide, Site industriel du Sactar, 85500 Bollène (France)

    2013-12-15

    Electroless nickel-high-phosphorus Ni–P plating is used as substrate coating in the electronic component technology. The ability to minimize pores formation in solder joints and the wettability of the Ni–P layer remain points of investigation. The qualities and the control of the physical and chemical properties of the deposits are essential for the reliability of the products. In this contribution it has been measured how a controlled change of one property of the Ni–P surface, its average roughness, changes the wettability of this surface before soldering completion, at ambient temperature and under ambient air, and how it contribute to change the amount and size of pores inside solder joints, after soldering completion. Before all, observations of the Ni–P surfaces using scanning electron microscopy have been achieved. Then the wettability has been measured through the determination of both the disperse and the polar fractions of the substrate surface tension, based on the measurements of the wetting angle for droplets of four different liquids, under ambient air and at room temperature (classical sessile drop technique). Finally the X-ray micro-radiography measurements of both the area fraction of pores and the size of the largest pore inside the solder joint of dice laser soldered on the studied substrate, using high melting temperature solder (300 °C, PbSnAg) have been achieved. This study clearly demonstrates that both the ability to minimize pores formation in solder joints and the wettability under ambient conditions of the Ni–P substrate decrease and become more variable when its average roughness increases. These effects can be explained considering the Cassie–Baxter model for rough surface wetting behaviour, completed by the model of heterogeneous nucleation and growth for gas bubbles inside a liquid.

  13. Arc spraying solderable tabs to glass

    Science.gov (United States)

    Lindmayer, J.

    1981-01-01

    Tabs suitable for electrical or mechanical connections in solar cells and integrated circuits are made by spraying technique. Solder wets copper, copper bonds to aluminum, and aluminum adheres to glass. Arc spraying is automated and integrated with encapsulation, eliminating hand tabbing, improving reliability, and reducing cost.

  14. New Failure Mode of Flip-Chip Solder Joints Related to the Metallization of an Organic Substrate

    Science.gov (United States)

    Jang, J. W.; Yoo, S. J.; Hwang, H. I.; Yuk, S. Y.; Kim, C. K.; Kim, S. J.; Han, J. S.; An, S. H.

    2015-10-01

    We report a new failure phenomenon during flip-chip die attach. After reflow, flip-chip bumps were separated between the Al and Ti layers on the Si die side. This was mainly observed at the Si die corner. Transmission electron microscopy images revealed corrosion of the Al layer at the edge of the solder bump metallization. The corrosion at the metallization edge exhibited a notch shape with high stress concentration factor. The organic substrate had Cu metallization with an organic solderable preservative (OSP) coating layer, where a small amount of Cl ions were detected. A solder bump separation mechanism is suggested based on the reaction between Al and Cl, related to the flow of soldering flux. During reflow, the flux will dissolve the Cl-containing OSP layer and flow up to the Al layer on the Si die side. Then, the Cl-dissolved flux will actively react with Al, forming AlCl3. During cooling, solder bumps at the Si die corner will separate through the location of Al corrosion. This demonstrated that the chemistry of the substrate metallization can affect the thermomechanical reliability of flip-chip solder joints.

  15. Immunogenicity of multi-epitope-based vaccine candidates administered with the adjuvant Gp96 against rabies.

    Science.gov (United States)

    Niu, Yange; Liu, Ye; Yang, Limin; Qu, Hongren; Zhao, Jingyi; Hu, Rongliang; Li, Jing; Liu, Wenjun

    2016-04-01

    Rabies, a zoonotic disease, causes > 55,000 human deaths globally and results in at least 500 million dollars in losses every year. The currently available rabies vaccines are mainly inactivated and attenuated vaccines, which have been linked with clinical diseases in animals. Thus, a rabies vaccine with high safety and efficacy is urgently needed. Peptide vaccines are known for their low cost, simple production procedures and high safety. Therefore, in this study, we examined the efficacy of multi-epitope-based vaccine candidates against rabies virus. The ability of various peptides to induce epitope-specific responses was examined, and the two peptides that possessed the highest antigenicity and conservation, i.e., AR16 and hPAB, were coated with adjuvant canine-Gp96 and used to prepare vaccines. The peptides were prepared as an emulsion of oil in water (O/W) to create three batches of bivalent vaccine products. The vaccine candidates possessed high safety. Virus neutralizing antibodies were detected on the day 14 after the first immunization in mice and beagles, reaching 5-6 IU/mL in mice and 7-9 IU/mL in beagles by day 28. The protective efficacy of the vaccine candidates was about 70%-80% in mice challenged by a virulent strain of rabies virus. Thus, a novel multi-epitope-based rabies vaccine with Gp96 as an adjuvant was developed and validated in mice and dogs. Our results suggest that synthetic peptides hold promise for the development of novel vaccines against rabies. PMID:27068655

  16. X-ray laminography analysis of ultra-fine-pitch solder connections on ultrathin boards

    Science.gov (United States)

    Adams, John A.

    1991-07-01

    As the demand increases for smaller, more powerful new products, design engineers are pressed to increase component densities while simultaneously reducing the size of interconnects. Almost every new product contains more solder joints per square inch than the previous one. New quad flatpack and TAB designs as small as 25 micron leads on 50 micron centers are in the prototype stage. Direct 'chip-on-board' (COB) components placed on a grid of solder bumps with a diameter of 75 microns and a grid of 200 microns are routinely being produced. Future plans include designs with a 25 micron diameter on 50 micron centers which are currently in development. Devices consisting of chips stacked upon chips and interconnected with solder or tungsten wires are increasingly included in new designs. Manufacturers have also begun to produce assemblies on very thin circuit boards with components on both sides. Several technologies have been applied in an effort to provide solder paste and post- reflow inspection. X-ray inspection has proven most effective at determining component placement and solder joint integrity. With its ability to pass freely through circuit board materials and extract detailed structural information from hidden and visible solder joints, the x-ray has proven more adept at assembled board inspection than other automated methods such as laser, ultrasonic, thermal and camera-based systems. This paper addresses the inspection and process control of ultra-thin boards with ultra fine pitch interconnects using x-ray laminography. In addition, the advantages and disadvantages of integrating various fine pitch technologies into the circuit board assembly process are reviewed.

  17. Calibration of the Gaia Radial Velocity Spectrometer from ground-based observations of candidate standard stars

    CERN Document Server

    Chemin, L; Crifo, F; Jasniewicz, G; Katz, D; Hestroffer, D; Udry, S

    2011-01-01

    The Radial Velocity Spectrometer (RVS) on board of Gaia will perform a large spectroscopic survey to determine the radial velocities of some 1.5x10^8 stars. We present the status of ground-based observations of a sample of 1420 candidate standard stars designed to calibrate the RVS. Each candidate star has to be observed several times before Gaia launch (and at least once during the mission) to ensure that its radial velocity remains stable during the whole mission. Observations are performed with the high-resolution spectrographs SOPHIE, NARVAL and CORALIE, completed with archival data of the ELODIE and HARPS instruments. The analysis shows that about 7% of the current catalogue exhibits variations larger than the adopted threshold of 300 m/s. Consequently, those stars should be rejected as reference targets, due to the expected accuracy of the Gaia RVS. Emphasis is also put here on our observations of bright asteroids to calibrate the ground-based velocities by a direct comparison with celestial mechanics. ...

  18. Network Based Integrated Analysis of Phenotype-Genotype Data for Prioritization of Candidate Symptom Genes

    Directory of Open Access Journals (Sweden)

    Xing Li

    2014-01-01

    Full Text Available Background. Symptoms and signs (symptoms in brief are the essential clinical manifestations for individualized diagnosis and treatment in traditional Chinese medicine (TCM. To gain insights into the molecular mechanism of symptoms, we develop a computational approach to identify the candidate genes of symptoms. Methods. This paper presents a network-based approach for the integrated analysis of multiple phenotype-genotype data sources and the prediction of the prioritizing genes for the associated symptoms. The method first calculates the similarities between symptoms and diseases based on the symptom-disease relationships retrieved from the PubMed bibliographic database. Then the disease-gene associations and protein-protein interactions are utilized to construct a phenotype-genotype network. The PRINCE algorithm is finally used to rank the potential genes for the associated symptoms. Results. The proposed method gets reliable gene rank list with AUC (area under curve 0.616 in classification. Some novel genes like CALCA, ESR1, and MTHFR were predicted to be associated with headache symptoms, which are not recorded in the benchmark data set, but have been reported in recent published literatures. Conclusions. Our study demonstrated that by integrating phenotype-genotype relationships into a complex network framework it provides an effective approach to identify candidate genes of symptoms.

  19. Candidate List of yoUr Biomarker (CLUB: A Web-based Platform to Aid Cancer Biomarker Research

    Directory of Open Access Journals (Sweden)

    N. Leigh Anderson

    2008-01-01

    Full Text Available CLUB (“Candidate List of yoUr Biomarkers” is a freely available, web-based resource designed to support Cancer biomarker research. It is targeted to provide a comprehensive list of candidate biomarkers for various cancers that have been reported by the research community. CLUB provides tools for comparison of marker candidates from different experimental platforms, with the ability to filter, search, query and explore, molecular interaction networks associated with cancer biomarkers from the published literature and from data uploaded by the community. This complex and ambitious project is implemented in phases. As a first step, we have compiled from the literature an initial set of differentially expressed human candidate cancer biomarkers. Each candidate is annotated with information from publicly available databases such as Gene Ontology, Swiss-Prot database, National Center for Biotechnology Information’s reference sequences, Biomolecular Interaction Network Database and IntAct interaction. The user has the option to maintain private lists of biomarker candidates or share and export these for use by the community. Furthermore, users may customize and combine commonly used sets of selection procedures and apply them as a stored workflow using selected candidate lists. To enable an assessment by the user before taking a candidate biomarker to the experimental validation stage, the platform contains the functionality to identify pathways associated with cancer risk, staging, prognosis, outcome in cancer and other clinically associated phenotypes. The system is available at http://club.bii.a-star.edu.sg.

  20. Effect of the Soldering Process on the Microstructure and Mechanical Properties of Sn-9Zn/Al Solder Joints

    Science.gov (United States)

    Yao, Yao; Feng, Xue; Jian, Zhou; Zhanying, Feng; Xu, Chen

    2015-08-01

    Tin-zinc solder alloys are considered to be appropriate for soldering of aluminum alloys at low-temperature in electronics and radiators applications. In this paper, the effects of different soldering parameters on the microstructure and interfacial reaction behaviors of 1070Al/Sn-9Zn/1070Al joints were investigated. The results show that the Al substrate was dissolved by the liquid solder, but Al-related intermetallic was not observed in the interface. Two kinds of Al-rich phases formed in the solder matrix. Large butterfly-shaped solid solution (Al)″ phases (about 10 μm) were formed in the liquid alloys, and compact-shaped precipitations (nano-size) were dissolved out from solders during solidification process. With increasing of the soldering time, Al″ phases were migrated upwards in the solders and the amount of this phase increased. In addition, with the increase of the soldering temperature, the dissolution rate of Al into the solder increased and the formation time of (Al)″ phases was reduced. Shear test results indicate when soldered at 250 °C, the shear strength increased from 48.6 MPa to a maximum 60.5 MPa and then decreased to a stable value (about 55 MPa) with increasing of the soldering time. Similar trends were also observed at 300 and 350 °C, while the soldering time needed to obtain maximum shear strength was shortened. The formation of these Al-rich phases improves the shear strength but deteriorates the ductility.

  1. Sn-Ag-Cu Nanosolders: Solder Joints Integrity and Strength

    Science.gov (United States)

    Roshanghias, Ali; Khatibi, Golta; Yakymovych, Andriy; Bernardi, Johannes; Ipser, Herbert

    2016-05-01

    Although considerable research has been dedicated to the synthesis and characterization of lead-free nanoparticle solder alloys, only very little has been reported on the reliability of the respective joints. In fact, the merit of nanoparticle solders with depressed melting temperatures close to the Sn-Pb eutectic temperature has always been challenged when compared with conventional solder joints, especially in terms of inferior solderability due to the oxide shell commonly present on the nanoparticles, as well as due to compatibility problems with common fluxing agents. Correspondingly, in the current study, Sn-Ag-Cu (SAC) nanoparticle alloys were combined with a proper fluxing vehicle to produce prototype nanosolder pastes. The reliability of the solder joints was successively investigated by means of electron microscopy and mechanical tests. As a result, the optimized condition for employing nanoparticles as a competent nanopaste and a novel procedure for surface treatment of the SAC nanoparticles to diminish the oxide shell prior to soldering are being proposed.

  2. Solder assembly of cantilever bar force or displacement sensors

    OpenAIRE

    Maeder, Thomas; Genoud, Dominique

    2001-01-01

    In this paper, the stability of a displacement sensor assembled with Sn96 (tin- silver) solder, Sn62 (tin-leadsilver) solder or conductive silver-loaded epoxy glue was compared. In the absence of humidity or thermal cycling, the glue was found to be much better than both solders. This is ascribed to better creep behaviour combined with lower elastic modulus and much smaller bond thickness. However, the glue underwent severe degradation in hot, humid air, and is therefore not suitable for...

  3. Site candidates for ground-based telescope devoted to space debris searching

    Science.gov (United States)

    Jiang, Hu; Hu, Haiying; Shen, Xue-min

    2015-12-01

    The demands for space debris scanning have been increasingly urgent in recent decade. The more space activities, the more urgent demands for space debris information. China has laid out space debris scanning from ground-based observation facilities. According to the latitudinal boundaries of China, north latitudes of 20deg, 30deg, 40deg, 50deg, 60deg are considered to be candidates for telescope sites. Space debris distribution is simulated under the assumption that telescopes are stationed in north latitudes of 20deg, 30deg, 40deg, 50deg, 60deg respectively. According to space debris simulations, it is recommended that the telescope dedicated to space debris scanning should be deployed in lower latitudes in order to achieve a better performance in detecting space debrises for China observing users.

  4. THERMAL PROCESS OF VACUUM FLUXLESS LASERSOLDERING AND ANALYSIS ON SOLDER SPREADING AND WETTING

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    In order to study the mechanism of vacuum fluxless soldering on the conditions of laser heating, the method of measuring temperature by the thermocouple is used to analyze the spreading and wetting process of boh fluxless SnPb solder in the vacuum surroundings and flux SnPb solder on Cu pad. Solder spreading and wetting affected by the soldering thermal process is also discussed according to the thermodynamics principle. Results show that vacuum fluxless soldering demands higher temperature, and the fall of the solder su rface tension is the important factor achieving fluxless laser soldering.

  5. Design and Experiment of a Solder Paste Jetting System Driven by a Piezoelectric Stack

    Directory of Open Access Journals (Sweden)

    Shoudong Gu

    2016-06-01

    Full Text Available To compensate for the insufficiency and instability of solder paste dispensing and printing that are used in the SMT (Surface Mount Technology production process, a noncontact solder paste jetting system driven by a piezoelectric stack based on the principle of the nozzle-needle-system is introduced in this paper, in which a miniscule gap exists between the nozzle and needle during the jetting process. Here, the critical jet ejection velocity is discussed through theoretical analysis. The relations between ejection velocity and needle structure, needle velocity, and nozzle diameter were obtained by FLUENT software. Then, the prototype of the solder paste jetting system was fabricated, and the performance was verified by experiments. The effects of the gap between nozzle and needle, the driving voltage, and the nozzle diameter on the jetting performance and droplet diameter were obtained. Solder paste droplets 0.85 mm in diameter were produced when the gap between the nozzle and needle was adjusted to 10 μm, the driving voltage to 80 V, the nozzle diameter to 0.1 mm, and the variation of the droplet diameter was within ±3%.

  6. Microstructural and mechanical properties analysis of extruded Sn–0.7Cu solder alloy

    Directory of Open Access Journals (Sweden)

    Abdoul-Aziz Bogno

    2015-01-01

    Full Text Available The properties and performance of lead-free solder alloys such as fluidity and wettability are defined by the alloy composition and solidification microstructure. Rapid solidification of metallic alloys is known to result in refined microstructures with reduced microsegregation and improved mechanical properties of the final products as compared to normal castings. The rapidly solidified Sn-based solders by melt spinning were shown to be suitable for soldering with low temperature and short soldering duration. In the present study, rapidly solidified Sn–0.7 wt.%Cu droplets generated by impulse atomization (IA were achieved as well as directional solidification under transient conditions at lower cooling rate. This paper reports on a comparative study of the rapidly solidified and the directionally solidified samples. Different but complementary characterization techniques were used to fully analyze the solidification microstructures of the samples obtained under the two cooling regimes. These include X-ray diffractometry (XRD and scanning electron microscopy (SEM. In order to compare the tensile strength and elongation to fracture of the directionally solidified ingot and strip castings with the atomized droplet, compaction and extrusion of the latter were carried out. It was shown that more balanced and superior tensile mechanical properties are available for the hot extruded samples from compacted as-atomized Sn–0.7 wt.%Cu droplets. Further, elongation-to-fracture was 2–3× higher than that obtained for the directionally solidified samples.

  7. A quick electrical inspection method of solder joint quality for LED products

    Science.gov (United States)

    Zhang, Jianhua; Que, Xiufu; Liu, Yanan; Chen, Weining; Tao, Guoqiao; Yang, Lianqiao

    2016-06-01

    Solder joint qualities of light-emitting diodes (LED) lamps have a significant effect on their lifetime. Due to variations in LEDs, the product lifetime is determined by the lowest performing component of the product when multi-LEDs are used. In this paper, we propose a quick electrical inspection method of solder joint quality for LED products, which is obtained by the heating curve measurement for a short time with the forward voltage as a temperature sensitive parameter. The utility of this quick inspection method is verified by the measurement of a solder voids ratio based on the most commonly used approaches in the industry—x-ray. The proposed method is cost effective and only needs around 1–5 s for each LED, which is about one third of the x-ray. Therefore, the quick electrical test method is both meaningful and promising especially when carrying out quality tests on large quantities of solder and can be a highly recommended method to be adopted by the LED lighting industry.

  8. Reliability Study of Solder Paste Alloy for the Improvement of Solder Joint at Surface Mount Fine-Pitch Components

    Directory of Open Access Journals (Sweden)

    Mohd Nizam Ab. Rahman

    2014-12-01

    Full Text Available The significant increase in metal costs has forced the electronics industry to provide new materials and methods to reduce costs, while maintaining customers’ high-quality expectations. This paper considers the problem of most electronic industries in reducing costly materials, by introducing a solder paste with alloy composition tin 98.3%, silver 0.3%, and copper 0.7%, used for the construction of the surface mount fine-pitch component on a Printing Wiring Board (PWB. The reliability of the solder joint between electronic components and PWB is evaluated through the dynamic characteristic test, thermal shock test, and Taguchi method after the printing process. After experimenting with the dynamic characteristic test and thermal shock test with 20 boards, the solder paste was still able to provide a high-quality solder joint. In particular, the Taguchi method is used to determine the optimal control parameters and noise factors of the Solder Printer (SP machine, that affects solder volume and solder height. The control parameters include table separation distance, squeegee speed, squeegee pressure, and table speed of the SP machine. The result shows that the most significant parameter for the solder volume is squeegee pressure (2.0 mm, and the solder height is the table speed of the SP machine (2.5 mm/s.

  9. Effect of Metal Bond-Pad Configurations on the Solder Microstructure Development of Flip-Chip Solder Joints

    Science.gov (United States)

    Hu, Y. J.; Hsu, Y. C.; Huang, T. S.; Lu, C. T.; Wu, Albert T.; Liu, C. Y.

    2014-01-01

    Various microstructural zones were observed in the solidified solder of flip-chip solder joints with three metal bond-pad configurations (Cu/Sn/Cu, Ni/Sn/Cu, and Cu/Sn/Ni). The developed microstructures of the solidified flip-chip solder joints were strongly related to the associated metal bond pad. A hypoeutectic microstructure always developed near the Ni bond pad, and a eutectic or hypereutectic microstructure formed near the Cu pad. The effect of the metal bond pads on the solder microstructure alters the Cu solubility in the molten solder. The Cu content (solubility) in the molten Sn(Cu) solder eventually leads to the development of particular microstructures. In addition to the effect of the associated metal bond pads, the developed microstructure of the flip-chip solder joint depends on the configuration of the metal bond pads. A hypereutectic microstructure formed near the bottom Cu pad, and a eutectic microstructure formed near the top Cu pad. Directional cooling in the flip-chip solder joint during the solidification process causes the effects of the metal bond-pad configuration. Directional cooling causes the Cu content to vary in the liquid Sn(Cu) phase, resulting in the formation of distinct microstructural zones in the developed microstructure of the flip-chip solder joint.

  10. Preparation of candidate reference materials for the determination of phosphorus containing flame retardants in styrene-based polymers.

    Science.gov (United States)

    Roth, Thomas; Urpi Bertran, Raquel; Latza, Andreas; Andörfer-Lang, Katrin; Hügelschäffer, Claudia; Pöhlein, Manfred; Puchta, Ralph; Placht, Christian; Maid, Harald; Bauer, Walter; van Eldik, Rudi

    2015-04-01

    Candidate reference materials (RM) for the analysis of phosphorus-based flame retardants in styrene-based polymers were prepared using a self-made mini-extruder. Due to legal requirements of the current restriction for the use of certain hazardous substances in electrical and electronic equipment, focus now is placed on phosphorus-based flame retardants instead of the brominated kind. Newly developed analytical methods for the first-mentioned substances also require RMs similar to industrial samples for validation and verification purposes. Hence, the prepared candidate RMs contained resorcinol-bis-(diphenyl phosphate), bisphenol A bis(diphenyl phosphate), triphenyl phosphate and triphenyl phosphine oxide as phosphorus-based flame retardants. Blends of polycarbonate and acrylonitrile-co-butadiene-co-styrene as well as blends of high-impact polystyrene and polyphenylene oxide were chosen as carrier polymers. Homogeneity and thermal stability of the candidate RMs were investigated. Results showed that the candidate RMs were comparable to the available industrial materials. Measurements by ICP/OES, FTIR and NMR confirmed the expected concentrations of the flame retardants and proved that analyte loss and degradation, respectively, was below the uncertainty of measurement during the extrusion process. Thus, the candidate RMs were found to be suitable for laboratory use. PMID:25410641

  11. Solid particle erosion of steels and nickel based alloys candidates for USC steam turbine blading

    Energy Technology Data Exchange (ETDEWEB)

    Cernuschi, Federico; Guardamagna, Cristina; Lorenzoni, Lorenzo [ERSE SpA, Milan (Italy); Robba, Davide [CESI, Milan (Italy)

    2010-07-01

    The main objective of COST536 Action is to develop highly efficient steam power plant with low emissions, from innovative alloy development to validation of component integrity. In this perspective, to improve the operating efficiency, materials capable of withstanding higher operating temperatures are required. For the manufacturing of components for steam power plants with higher efficiency steels and nickel-based alloys with improved oxidation resistance and creep strength at temperature as high as 650 C - 700 C have to be developed. Candidate alloys for manufacturing high pressure steam turbine diaphragms, buckets, radial seals and control valves should exhibit, among other properties, a good resistance at the erosion phenomena induced by hard solid particles. Ferric oxide (magnetite) scales cause SPE by exfoliating from boiler tubes and steam pipes (mainly super-heaters and re-heaters) and being transported within the steam flow to the turbine. In order to comparatively study the erosion behaviour of different materials in relatively short times, an accelerated experimental simulation of the erosion phenomena must be carried out. Among different techniques to induce erosion on material targets, the use of an air jet tester is well recognised to be one of the most valid and reliable. In this work the results of SPE comparative tests performed at high temperatures (550 C, 600 C and 650 C) at different impaction angles on some steels and nickel based alloys samples are reported. (orig.)

  12. A PROJECT-BASED LEARNING PACKAGE FOR PH. D CANDIDATES AT HIT

    Institute of Scientific and Technical Information of China (English)

    ZhaoYuqin

    2004-01-01

    Project-based learning is to involve students in a project-like learning program to achieve the required purposes of language learning, It is a new pedagogical approach composed of a series of tasks, requiring students to use various languages and other skills to accomplish respectively. It is to provide students with opportunities to learn the language in a simulated authentic communicative situation when they are using the language. A project-based learning program was desigued for the Ph. D.candidates at HIT, named “simulating an international conference”. It involves the students in the whole process of organizing and participating an international conference. In the simulated context, students have opportunities to learn and practice English while they are using English to fulfill some tasks. Meanwhile, students are able to practice other skills, such as using information technologies, word editing and publishing. More importantly, students need to collaborate and cooperate with each other. The abilities to use English as a communicative tool for international communication, to use information technologies and to be able to cooperate with other sare the aims of education in the 21st century.

  13. A Sub-Pathway Based Method to Identify Candidate Agents for Ankylosing Spondylitis

    Directory of Open Access Journals (Sweden)

    Ming Li

    2012-10-01

    Full Text Available The need for new therapeutics for Ankylosing Spondylitis (AS is highlighted by the general lack of efficacy for most agents currently available for this disease. Many recent studies have detailed molecular pathways in AS, and several molecule-targeting agents are undergoing evaluation. We aimed to explore the mechanism of AS and identify biologically active small molecules capable of targeting the sub-pathways which were disregulated in the development of AS. By using the GSE25101 microarray data accessible from the Gene Expression Omnibus database, we first identified the differentially expressed genes (DEGs between AS samples and healthy controls, followed by the sub-pathway enrichment analysis of the DEGs. In addition, we propose the use of an approach based on targeting sub-pathways to identify potential agents for AS. A total of 3,280 genes were identified as being significantly different between patients and controls with p-values < 0.1. Our study showed that neurotrophic signaling pathway and some immune-associated pathways may be involved in the development of AS. Besides, our bioinformatics analysis revealed a total of 15 small molecules which may play a role in perturbing the development of AS. Our study proposes the use of an approach based on targeting sub-pathways to identify potential agents for AS. Candidate agents identified by our approach may provide the groundwork for a combination therapy approach for AS.

  14. Computerized detection of multiple sclerosis candidate regions based on a level set method using an artificial neural network

    International Nuclear Information System (INIS)

    Yamamoto et al. developed the system for computer-aided detection of multiple sclerosis (MS) candidate regions. In a level set method in their proposed method, they employed the constant threshold value for the edge indicator function related to a speed function of the level set method. However, it would be appropriate to adjust the threshold value to each MS candidate region, because the edge magnitudes in MS candidates differ from each other. Our purpose of this study was to develop a computerized detection of MS candidate regions in MR images based on a level set method using an artificial neural network (ANN). To adjust the threshold value for the edge indicator function in the level set method to each true positive (TP) and false positive (FP) region, we constructed the ANN. The ANN could provide the suitable threshold value for each candidate region in the proposed level set method so that TP regions can be segmented and FP regions can be removed. Our proposed method detected MS regions at a sensitivity of 82.1% with 0.204 FPs per slice and similarity index of MS candidate regions was 0.717 on average. (author)

  15. AuSn Solder Packaging in Vacuum Oven%真空炉金锡封焊

    Institute of Scientific and Technical Information of China (English)

    刘艳; 徐骁; 陈洁民; 陈凯

    2012-01-01

      In this paper,with the introduction of semiconductor packaging technology of AuSn solder, emphasis on the deep research of technology problems of AuSn solder and temperature curve settings. Based on many vacuum AuSn solder packaging experiments and theoretical analysis,research the technologies of module gas-tight packaging. Discusses the effects of packaging fixture,lid plating layer,alloy state,interface,pressing block,solder thickness and heating process to the solder packaging. The gas-tight performance can be fairly meet after environment mechanism test. The feasibility of alloy used and packaging technique can be proved according to the application background.%  文章在介绍半导体金锡焊料封装工艺的基础上,重点对金锡焊料、炉温曲线设置等工艺技术问题进行了深入研究。基于大量的金锡焊料真空焊接封装实验及理论分析,研究了器件气密封装技术。讨论了封焊夹具、管帽镀层、合金状态、封接面表面、压块、焊料厚度以及加热程序对焊接质量的影响。密封后的产品在经过环境试验和机械试验考核后,封装气密性能很好地满足要求。并且结合应用背景证明了所采用的合金及封装工艺的可行性。

  16. Candidate Gene Analysis Suggests Untapped Genetic Complexity in Melanin-Based Pigmentation in Birds.

    Science.gov (United States)

    Bourgeois, Yann X C; Bertrand, Joris A M; Delahaie, Boris; Cornuault, Josselin; Duval, Thomas; Milá, Borja; Thébaud, Christophe

    2016-07-01

    Studies on melanin-based color variation in a context of natural selection have provided a wealth of information on the link between phenotypic and genetic variation. Here, we evaluated associations between melanic plumage patterns and genetic polymorphism in the Réunion grey white-eye (Zosterops borbonicus), a species in which mutations on MC1R do not seem to play any role in explaining melanic variation. This species exhibits 5 plumage color variants that can be grouped into 3 color forms which occupy discrete geographic regions in the lowlands of Réunion, and a fourth high-elevation form which comprises 2 color morphs (grey and brown) and represents a true color polymorphism. We conducted a comprehensive survey of sequence variation in 96 individuals at a series of 7 candidate genes other than MC1R that have been previously shown to influence melanin-based color patterns in vertebrates, including genes that have rarely been studied in a wild bird species before: POMC, Agouti, TYR, TYRP1, DCT, Corin, and SLC24A5 Of these 7 genes, 2 (Corin and TYRP1) displayed an interesting shift in allele frequencies between lowland and highland forms and a departure from mutation-drift equilibrium consistent with balancing selection in the polymorphic highland form only. Sequence variation at Agouti, a gene frequently involved in melanin-based pigmentation patterning, was not associated with color forms or morphs. Thus, we suggest that functionally important changes in loci other than those classically studied are involved in the color polymorphism exhibited by the Réunion grey white-eye and possibly many other nonmodel species. PMID:26995742

  17. Trust Based Algorithm for Candidate Node Selection in Hybrid MANET-DTN

    Directory of Open Access Journals (Sweden)

    Jan Papaj

    2014-01-01

    Full Text Available The hybrid MANET - DTN is a mobile network that enables transport of the data between groups of the disconnected mobile nodes. The network provides benefits of the Mobile Ad-Hoc Networks (MANET and Delay Tolerant Network (DTN. The main problem of the MANET occurs if the communication path is broken or disconnected for some short time period. On the other side, DTN allows sending data in the disconnected environment with respect to higher tolerance to delay. Hybrid MANET - DTN provides optimal solution for emergency situation in order to transport information. Moreover, the security is the critical factor because the data are transported by mobile devices. In this paper, we investigate the issue of secure candidate node selection for transportation of the data in a disconnected environment for hybrid MANET- DTN. To achieve the secure selection of the reliable mobile nodes, the trust algorithm is introduced. The algorithm enables select reliable nodes based on collecting routing information. This algorithm is implemented to the simulator OPNET modeler.

  18. Cell-Based Assay Design for High-Content Screening of Drug Candidates.

    Science.gov (United States)

    Nierode, Gregory; Kwon, Paul S; Dordick, Jonathan S; Kwon, Seok-Joon

    2016-02-01

    To reduce attrition in drug development, it is crucial to consider the development and implementation of translational phenotypic assays as well as decipher diverse molecular mechanisms of action for new molecular entities. High-throughput fluorescence and confocal microscopes with advanced analysis software have simplified the simultaneous identification and quantification of various cellular processes through what is now referred to as highcontent screening (HCS). HCS permits automated identification of modifiers of accessible and biologically relevant targets and can thus be used to detect gene interactions or identify toxic pathways of drug candidates to improve drug discovery and development processes. In this review, we summarize several HCS-compatible, biochemical, and molecular biology-driven assays, including immunohistochemistry, RNAi, reporter gene assay, CRISPR-Cas9 system, and protein-protein interactions to assess a variety of cellular processes, including proliferation, morphological changes, protein expression, localization, post-translational modifications, and protein-protein interactions. These cell-based assay methods can be applied to not only 2D cell culture but also 3D cell culture systems in a high-throughput manner. PMID:26428732

  19. Current Status of Lead-Free Soldering and Conductive Adhesives

    Institute of Scientific and Technical Information of China (English)

    KatsuakiSuganuma

    2003-01-01

    Lead-free soldering technology took offin the Japanese market during the year 2000, and as the year 2001-03 ushered in the 21 st century, a large number of products with lead-free soldering were already appearing on store shelves. Elsewhere, EU deliberation on the draft of the WEEE/RoHS directive finalized in February 2003 and be in force in July 2006. The course had been set for adopting lead-free solder for mounting processes of parts as well, bringing the possibility of lead-free solder mounting very close to achievement. This review will provide a view of the current state of technological progress in lead-free soldering, both in Japan and abroad, and will discuss future prospects.

  20. Development of lead-free solders for hybrid microcircuits

    Energy Technology Data Exchange (ETDEWEB)

    Hosking, F.M.; Vianco, P.T.; Frear, D.R.; Robinson, D.G.

    1996-01-01

    Extensive work has been conducted by industry to develop lead-free solders for electronics applications. The driving force behind this effort is pressure to ban or tax the use of lead-bearing solders. There has been further interest to reduce the use of hazardous chemical cleaners. Lead-free soldering and low-residue, ``no clean`` assembly processing are being considered as solutions to these environmental issues. Most of the work has been directed toward commercial and military printed wiring board (PWB) technology, although similar problems confront the hybrid microcircuit (HMC) industry, where the development of lead-free HMC solders is generally lagging. Sandia National Laboratories is responsible for designing a variety of critical, high reliability hybrid components for radars. Sandia has consequently initiated a project, as part of its Environmentally Conscious Manufacturing program, to develop low-residue, lead-free soldering for HMCs. This paper discusses the progress of that work.

  1. Laser beam soldering of fine-pitch technology packages with solid solder deposits

    Science.gov (United States)

    Pucher, Hans-Joerg; Glasmacher, Mathias; Geiger, Manfred

    1996-04-01

    Micro electronics is a key technology attracting the attention of information, communication, automation and data processing technologies. Ongoing miniaturization combined with an increasing number of I/Os has inevitably lead to ever finer lead geometries. Therefore the demands put upon the surface mount technology are increasing continuously. Processing of high lead count fine pitch packages, for example those which are applied in high-capacity computers, has not increased the demands put upon the assembly process only, but also on the connecting techniques. By reflow soldering with laser beam radiation the benefits from the tool `laser beam' are used extensively, for example contact and force free processing, strictly localized heating and the good controllability thereof, formation of fine crystalline and homogeneous structures, etc. Within the scope of this paper the fundamentals of laser beam soldering are discussed for fine pitch lead frames (pitch 300 micrometers ) for plastic packages, made by a modified CuFe2P alloy with a 5 micrometers Sn90Pb plating, on solid solder depths (Sn63Pb) performed by the so called High-Pad process. These investigations are unique in the field of laser beam soldering and are carried out by means of a Nd:YAG-laser. A pyrometer is used for detection of the emission of the temperature radiation of the joining area for process control. The additional use of a high-speed camera gives a detailed description of the melting and wetting process. The influence of laser beam parameters and the volume of the solid solder deposits on the joining result are presented.

  2. Detection of the early keratoconus based on corneal biomechanical properties in the refractive surgery candidates

    Directory of Open Access Journals (Sweden)

    Zofia Pniakowska

    2016-01-01

    Full Text Available Context: Subclinical keratoconus is contraindication to refractive surgery. The currently used methods of preoperative screening do not always allow differentiating between healthy eyes and those with subclinical keratoconus. Aim: To evaluate biomechanical parameters of the cornea, waveform score (WS, and intraocular pressure (IOP as potentially useful adjuncts to the diagnostic algorithm for precise detection of the early keratoconus stages and selection of refractive surgery candidates. Settings and Design: Department of Ophthalmology and prospective cross-sectional study. Patients and Methods: Patients enrolled in the study were diagnosed with refractive disorders. We assessed parameters of corneal biomechanics such as corneal hysteresis (CH, corneal resistance factor (CRF, Goldman-correlated IOP (IOPg, corneal compensated IOP, WS, and keratoconus match index (KMI. They were classified into one of three groups based on the predefined KMI range: Group 1 (from 0.352 to 0.757 – 45 eyes, Group 2 (from −0.08 to 0.313 – 52 eyes, and Group 0 - control group (from 0.761 to 1.642 – 80 eyes. Results: In both study groups, IOPg, CRF, and CH were decreased when compared to control (P < 0.0001. In control group, there was positive correlation between CH and KMI (P < 0.05, with no correlations in any of the two study groups. CRF correlated positively with KMI in control (P < 0.0001 and in Group 2 (P < 0.05. Conclusions: CH and CRF, together with WS and IOPg, consist a clinically useful adjunct to detect subclinical keratoconus in patients referred for refractive surgery when based on KMI staging.

  3. Power Cycling Test Circuit for Thermal Fatigue Resistance Analysis of Solder Joints in IGBT

    OpenAIRE

    Dupont, Laurent; Lefebvre, Stéphane; Khatir, Zoubir; FAUGIERE, Jean Claude

    2003-01-01

    The paper will give a detailed presentation of an active power cycling test bench in high temperature conditions developed to ageing the solder between the Direct Copper Bonding (DCB) and the base of IGBT devices. The average junction temperature measurement protocol, the temperature regulation of the base plate, the acquisition of all the electrical signals, and the performance of the test circuit will be presented and discussed. Moreover, a thermal modelling presentation has been used to de...

  4. Break-up Process of Perturbed Molten Metal Jet and Preparation of Lead-Free Solder Balls

    Institute of Scientific and Technical Information of China (English)

    He Lijun; Zhang Shuguang; Zhang Shaoming; Xu Jun; Shi Likai

    2004-01-01

    Solder balls, which are used in advanced electronics packages such as BGA (Ball Grid Array) and CSP (Chip Scale Package) to substitute the leads and realize the electrical and mechanical connections between substrate and chip,have severe specifications in diameter tolerance, roundness and surface quality, and therefore challenge the traditional technologies for fabrication of metallic particles and powders. The present work made a survey of perturbed molten metal jet break-up process, observed the formation and growth of capillary wave of tin-lead melt jet by way of rapid solidification, and on the basis of the above research, successfully obtained tin-lead eutectic and Sn-4.0Ag-0.5Cu lead free solder balls with tight distribution and good sphericity of particles through optimization of processing parameters, forming a solid base for cost effectively producing solder balls.

  5. Effects Of Nickel On The Microstructure And The Mechanical Properties Of Sn-0.7Cu Lead-Free Solders

    Directory of Open Access Journals (Sweden)

    Gyenes A.

    2015-06-01

    Full Text Available This paper investigates the effects of small amount nickel addition (0, 200, 400, 800, 1800 ppm on the microstructure and the mechanical properties of Sn-0.7Cu lead-free solder alloys. It is known that even ppm level Ni additions have significant effects on the microstructure of Sn-Cu solder alloys. Ni suppresses the growth of β-Sn dendrites in favour of eutectic formation. As the nickel content increases, the microstructure undergoes a morphological evolution from hypoeutectic through fully eutectic to hypereutectic. Along with these transformations, the mechanical properties of the alloy also significantly change. Based on the experimental results presented in this paper, the Sn-0.7Cu solder achieves maximum strength at the addition level of 800 ppm Ni, when the microstructure becomes fully eutectic.

  6. Comparative Evaluation of Marginal Accuracy of a Cast Fixed Partial Denture Compared to Soldered Fixed Partial Denture Made of Two Different Base Metal Alloys and Casting Techniques: An In vitro Study

    OpenAIRE

    Jei, J. Brintha; Mohan, Jayashree

    2013-01-01

    The periodontal health of abutment teeth and the durability of fixed partial denture depends on the marginal adaptation of the prosthesis. Any discrepancy in the marginal area leads to dissolution of luting agent and plaque accumulation. This study was done with the aim of evaluating the accuracy of marginal fit of four unit crown and bridge made up of Ni–Cr and Cr–Co alloys under induction and centrifugal casting. They were compared to cast fixed partial denture (FPD) and soldered FPD. For t...

  7. Effect of solder bump size on interfacial reactions during soldering between Pb-free solder and Cu and Ni/ Pd/ Au surface finishes

    International Nuclear Information System (INIS)

    Flip chip technology provides the ultimate in high I/ O-density and count with superior electrical performance for interconnecting electronic components. Therefore, the study of the intermetallic compounds was conducted to investigate the effect of solder bumps sizes on several surface finishes which are copper and Electroless Nickel/ Electroless Palladium/ Immersion Gold (ENEPIG) which is widely used in electronics packaging as surface finish for flip-chip application nowadays. In this research, field emission scanning electron microscopy (FESEM) analysis was conducted to analyze the morphology and composition of intermetallic compounds (IMCs) formed at the interface between the solder and UBM. The IMCs between the SAC lead-free solder with Cu surface finish after reflow were mainly (Cu, Ni)6Sn5 and Cu6Sn5. While the main IMCs formed between lead-free solder on ENEPIG surface finish are (Ni, Cu)3Sn4 and Ni3Sn4. The results from FESEM with energy dispersive x-ray (EDX) have revealed that isothermal aging at 150 degree Celsius has caused the thickening and coarsening of IMCs as well as changing them into more spherical shape. The thickness of the intermetallic compounds in both finishes investigated was found to be higher in solders with smaller bump size. From the experimental results, it also appears that the growth rate of IMCs is higher when soldering on copper compared to ENEPIG finish. Besides that, the results also showed that the thickness of intermetallic compounds was found to be proportional to isothermal aging duration. (author)

  8. Fatigue and thermal fatigue of Pb-Sn solder joints

    International Nuclear Information System (INIS)

    This paper presents a fundamental investigation of the fatigue and thermal fatigue characteristics, with an emphasis on the microstructural development during fatigue, of Sn-Pb solder joints. Fatigue tests were performed in simple shear on both 60Sn-40Pb and 5Sn-95Pb solder joints. Isothermal fatigue tests show increasing fatigue life of 60Sn-40Pb solder joints with decreasing strain and temperature. In contrast, such behavior was not observed in the isothermal fatigue of 5Sn-95Pb solder joints. Thermal fatigue results on 60Sn-40Pb solder cycled between -550C and 1250C show that a coarsened region develops in the center of the joint. Both Pb-rich and Sn-rich phases coarsen, and cracks form within these coarsened regions. The failure mode 60Sn-40Pb solder joints in thermal and isothermal fatigue is similar: cracks form intergranularly through the Sn-rich phase or along Sn/Pb interphase boundaries. Extensive cracking is found throughout the 5Sn-95Pb joint for both thermal and isothermal fatigue. In thermal fatigue the 5Sn-95Pb solder joints failed after fewer cycles than 60Sn-40Pb

  9. Environmentally compatible solder materials for thick film hybrid assemblies

    Energy Technology Data Exchange (ETDEWEB)

    Hosking, F.M.; Vianco, P.T.; Rejent, J.A.; Hernandez, C.L. [Sandia National Labs., Albuquerque, NM (United States). Materials and Process Sciences Center

    1997-02-01

    New soldering materials and processes have been developed over the last several years to address a variety of environmental issues. One of the primary efforts by the electronics industry has involved the development of alternative solders to replace the traditional lead-containing alloys. Sandia National Laboratories is developing such alternative solder materials for printed circuit board and hybrid microcircuit (HMC) applications. This paper describes the work associated with low residue, lead-free soldering of thick film HMC`s. The response of the different materials to wetting, aging, and mechanical test conditions was investigated. Hybrid test vehicles were designed and fabricated with a variety of chip capacitors and leadless ceramic chip carriers to conduct thermal, electrical continuity, and mechanical evaluations of prototype joints. Microstructural development along the solder and thick film interface, after isothermal solid state aging over a range of elevated temperatures and times, was quantified using microanalytical techniques. Flux residues on soldered samples were stressed (temperature-humidity aged) to identify potential corrosion problems. Mechanical tests also supported the development of a solder joint lifetime prediction model. Progress of this effort is summarized.

  10. A New Strategy Based on Smrho Protein Loaded Chitosan Nanoparticles as a Candidate Oral Vaccine against Schistosomiasis

    OpenAIRE

    Oliveira, Carolina R.; Rezende, Cíntia M. F.; Silva, Marina R.; Ana Paula Pêgo; Olga Borges; Alfredo M. Goes

    2012-01-01

    BACKGROUND: Schistosomiasis is one of the most important neglected tropical diseases and an effective control is unlikely in the absence of improved sanitation and vaccination. A new approach of oral vaccination with alginate coated chitosan nanoparticles appears interesting because their great stability and the ease of target accessibility, besides of chitosan and alginate immunostimulatory properties. Here we propose a candidate vaccine based on the combination of chitosan-based nanoparticl...

  11. Investigation on the Microstructure, Interfacial IMC Layer, and Mechanical Properties of Cu/Sn-0.7Cu-xNi/Cu Solder Joints

    Science.gov (United States)

    Yang, Li; Ge, Jinguo; Zhang, Yaocheng; Dai, Jun; Liu, Haixiang; Xiang, Jicen

    2016-04-01

    Sn-0.7Cu-xNi composite solder has been fabricated via mechanical mixing of different weight percentages of Ni particles with Sn-0.7Cu solder paste, and the effect of the Ni concentration on the microstructure, wettability, and tensile properties of Cu/Sn-0.7Cu-xNi/Cu solder joints investigated. The results show that refined dot-shaped particles of intermetallic compounds (IMCs) are uniformly dispersed in a primary β-Sn matrix in the Cu/Sn-0.7Cu-(0.05-0.1)Ni/Cu solder joints. The interfacial IMC layer thickness increased slightly when adding Ni content to 0.05 wt.%, then rapidly when further increasing the Ni concentration to 0.4 wt.%. Excellent wettability with bright appearance was obtained for the Sn-0.7Cu-0.05Ni solder due to diminished interfacial tension. The tensile properties improved after adding Ni content to 0.05 wt.% due to the presence of the refined dot-like IMC particles, in agreement with theoretical predictions based on the combination of dispersion and grain-refinement strengthening mechanisms. Refined microstructure and enhanced mechanical properties were obtained for the Cu/Sn-0.7Cu-0.05Ni/Cu solder joint.

  12. An Exploration of Initial Certification Candidates' TPACK and Mathematics-Based Applications Using Touch Device Technology

    Science.gov (United States)

    McCrory, Michael Ray

    2010-01-01

    This qualitative research study employed a multiple-case study approach to describe the experiences of a group of Initial Certification Candidates (ICCs) as they participated in explorations of readings and third-party applications (apps) run on touch screen technology devices. The group of ICCs was comprised of two Undergraduate Teacher…

  13. A Novel Technique for the Connection of Ceramic and Titanium Implant Components Using Glass Solder Bonding

    OpenAIRE

    Enrico Mick; Joachim Tinschert; Aurica Mitrovic; Rainer Bader

    2015-01-01

    Both titanium and ceramic materials provide specific advantages in dental implant technology. However, some problems, like hypersensitivity reactions, corrosion and mechanical failure, have been reported. Therefore, the combining of both materials to take advantage of their pros, while eliminating their respective cons, would be desirable. Hence, we introduced a new technique to bond titanium and ceramic materials by means of a silica-based glass ceramic solder. Cylindrical compound samples (...

  14. Solder technology in the manufacturing of electronic products

    Energy Technology Data Exchange (ETDEWEB)

    Vianco, P.T.

    1993-08-01

    The electronics industry has relied heavily upon the use of soldering for both package construction and circuit assembly. The solder attachment of devices onto printed circuit boards and ceramic microcircuits has supported the high volume manufacturing processes responsible for low cost, high quality consumer products and military hardware. Defects incurred during the manufacturing process are minimized by the proper selection of solder alloys, substrate materials and process parameters. Prototyping efforts are then used to evaluate the manufacturability of the chosen material systems. Once manufacturing feasibility has been established, service reliability of the final product is evaluated through accelerated testing procedures.

  15. Solder extrusion pressure bonding process and bonded products produced thereby

    Science.gov (United States)

    Beavis, Leonard C.; Karnowsky, Maurice M.; Yost, Frederick G.

    1992-01-01

    Production of soldered joints which are highly reliable and capable of surviving 10,000 thermal cycles between about -40.degree. C. and 110.degree. C. Process involves interposing a thin layer of a metal solder composition between the metal surfaces of members to be bonded and applying heat and up to about 1000 psi compression pressure to the superposed members, in the presence of a reducing atmosphere, to extrude the major amount of the solder composition, contaminants including fluxing gases and air, from between the members being bonded, to form a very thin, strong intermetallic bonding layer having a thermal expansion tolerant with that of the bonded members.

  16. Physics of failure as a basis for solder elements reliability assessment in wind turbines

    International Nuclear Information System (INIS)

    Traditionally assessment of reliability of electrical components is done by classical reliability techniques using failure rates as the basic measure of reliability. In this paper a structural reliability approach is applied in order to include all relevant uncertainties and to give a more detailed description of the reliability. A physics of failure approach is applied. A SnAg solder component used in power electronics is used as an example. Crack propagation in the SnAg solder is modeled and a model to assess the accumulated plastic strain is proposed based on a physics of failure approach. Based on the proposed model it is described how to find the accumulated linear damage and reliability levels for a given temperature loading profile. Using structural reliability methods the reliability levels of the electrical components are assessed by introducing scale factors for stresses. - Highlights: ► Physics of failure as a basis for reliability assessment. ► Failure mechanism based on component microstructure. ► SnAg solder fatigue and damage modeling in Wind Turbines. ► Structural reliability techniques for electrical components reliability assessment. ► Scale factor estimation for temperature loadings.

  17. Decomposition studies of no-clean solder flux systems in connection with corrosion reliability of electronics

    DEFF Research Database (Denmark)

    Conseil, Helene; Jellesen, Morten Stendahl; Verdingovas, Vadimas;

    2013-01-01

    One of the predominant factors for accelerated corrosion in electronics is the intrinsic contamination on Printed Circuit Board Assemblies (PCBAs) originating from the soldering process used for component mounting. However, the amount, distribution, and morphology of flux residue vary considerably...... with specific soldering process and parameters, while most important factors are the flux chemistry and its decomposition characteristics. Active parts of the flux residue can cause increased water absorption due to their hygroscopic nature and in solution they will increase leakage current and corrosion...... such as electrochemical migration resulting in intermittent or permanent failures. This paper summarizes the investigations on decomposition of some typical no-clean flux systems (WOA based) which are used today for the electronic manufacturing. The change in flux chemistry was studied as a function of temperature...

  18. Fully Pipelined Parallel Architecture for Candidate Block and Pixel-Subsampling-Based Motion Estimation

    Directory of Open Access Journals (Sweden)

    Reeba Korah

    2008-01-01

    Full Text Available This paper presents a low power and high speed architecture for motion estimation with Candidate Block and Pixel Subsampling (CBPS Algorithm. Coarse-to-fine search approach is employed to find the motion vector so that the local minima problem is totally eliminated. Pixel subsampling is performed in the selected candidate blocks which significantly reduces computational cost with low quality degradation. The architecture developed is a fully pipelined parallel design with 9 processing elements. Two different methods are deployed to reduce the power consumption, parallel and pipelined implementation and parallel accessing to memory. For processing 30 CIF frames per second our architecture requires a clock frequency of 4.5 MHz.

  19. Genetic relationships of some Citrus genotypes based on the candidate iron chlorosis genes

    OpenAIRE

    KAÇAR, Yıldız AKA; Özhan ŞİMŞEK; DÖNMEZ, Dicle; BONCUK, Melda; YEŞİLOĞLU, Turgut; Ollitrault, Patrick

    2014-01-01

    Iron is one of the most important elements in plant mineral nutrition. Fe deficiency is a critical abiotic stress factor for Mediterranean citriculture; the development of marker-assisted selection for this trait would greatly enhance rootstock breeding. In this study, DNA sequencing and single-stranded conformation polymorphism (SSCP) analyses were performed to determine the allelic diversity of genes associated with tolerance to iron chlorosis in citrus. Two candidate iron chlorosis toleran...

  20. Precision dispensing of small volumes of albumin solder for laser-assisted wound closure

    Science.gov (United States)

    Sorg, Brian S.; McNally-Heintzelman, Karen M.; Chan, Eric K.; Frederickson, Christopher J.; Welch, Ashley J.

    1999-06-01

    Recent laser-tissue soldering work in our lab has demonstrated the feasibility of building a solder bond from individually coagulated small droplets using a precision pipette for the deposition of the solder droplets. This method of using small, precise volumes of solder to build a bond may result in stronger and more reproducible bonds than coagulating an equivalent large volume of solder all at once. We have investigated the technique further in this study. The solder was dispensed onto the intimal side of a bovine aorta substrate and irradiated with an 808nm diode laser. A bond was created across an incision in the tissue substrate by alternately dispensing and coagulating each small volume of solder, or by coagulating a single large equivalent volume. Acute strength analysis was performed on the solder bond. Future work will concentrate on testing a bench-top solder dispensing device and investigating the feasibility of turning the deice into a prototype tool for clinical applications.

  1. Identification of plasma biomarker candidates in glioblastoma using an antibody-array-based proteomic approach

    International Nuclear Information System (INIS)

    Glioblastoma multiforme (GBM) is a brain tumour with a very high patient mortality rate, with a median survival of 47 weeks. This might be improved by the identification of novel diagnostic, prognostic and predictive therapy-response biomarkers, preferentially through the monitoring of the patient blood. The aim of this study was to define the impact of GBM in terms of alterations of the plasma protein levels in these patients. We used a commercially available antibody array that includes 656 antibodies to analyse blood plasma samples from 17 healthy volunteers in comparison with 17 blood plasma samples from patients with GBM. We identified 11 plasma proteins that are statistically most strongly associated with the presence of GBM. These proteins belong to three functional signalling pathways: T-cell signalling and immune responses; cell adhesion and migration; and cell-cycle control and apoptosis. Thus, we can consider this identified set of proteins as potential diagnostic biomarker candidates for GBM. In addition, a set of 16 plasma proteins were significantly associated with the overall survival of these patients with GBM. Guanine nucleotide binding protein alpha (GNAO1) was associated with both GBM presence and survival of patients with GBM. Antibody array analysis represents a useful tool for the screening of plasma samples for potential cancer biomarker candidates in small-scale exploratory experiments; however, clinical validation of these candidates requires their further evaluation in a larger study on an independent cohort of patients

  2. Identification of Novel Potential Vaccine Candidates against Tuberculosis Based on Reverse Vaccinology

    Directory of Open Access Journals (Sweden)

    Gloria P. Monterrubio-López

    2015-01-01

    Full Text Available Tuberculosis (TB is a chronic infectious disease, considered as the second leading cause of death worldwide, caused by Mycobacterium tuberculosis. The limited efficacy of the bacillus Calmette-Guérin (BCG vaccine against pulmonary TB and the emergence of multidrug-resistant TB warrants the need for more efficacious vaccines. Reverse vaccinology uses the entire proteome of a pathogen to select the best vaccine antigens by in silico approaches. M. tuberculosis H37Rv proteome was analyzed with NERVE (New Enhanced Reverse Vaccinology Environment prediction software to identify potential vaccine targets; these 331 proteins were further analyzed with VaxiJen for the determination of their antigenicity value. Only candidates with values ≥0.5 of antigenicity and 50% of adhesin probability and without homology with human proteins or transmembrane regions were selected, resulting in 73 antigens. These proteins were grouped by families in seven groups and analyzed by amino acid sequence alignments, selecting 16 representative proteins. For each candidate, a search of the literature and protein analysis with different bioinformatics tools, as well as a simulation of the immune response, was conducted. Finally, we selected six novel vaccine candidates, EsxL, PE26, PPE65, PE_PGRS49, PBP1, and Erp, from M. tuberculosis that can be used to improve or design new TB vaccines.

  3. Phylogeography, Salinity Adaptations and Metabolic Potential of the Candidate Division KB1 Bacteria Based on a Partial Single Cell Genome.

    Science.gov (United States)

    Nigro, Lisa M; Hyde, Andrew S; MacGregor, Barbara J; Teske, Andreas

    2016-01-01

    Deep-sea hypersaline anoxic basins and other hypersaline environments contain abundant and diverse microbial life that has adapted to these extreme conditions. The bacterial Candidate Division KB1 represents one of several uncultured groups that have been consistently observed in hypersaline microbial diversity studies. Here we report the phylogeography of KB1, its phylogenetic relationships to Candidate Division OP1 Bacteria, and its potential metabolic and osmotic stress adaptations based on a partial single cell amplified genome of KB1 from Orca Basin, the largest hypersaline seafloor brine basin in the Gulf of Mexico. Our results are consistent with the hypothesis - previously developed based on (14)C incorporation experiments with mixed-species enrichments from Mediterranean seafloor brines - that KB1 has adapted its proteins to elevated intracellular salinity, but at the same time KB1 apparently imports glycine betaine; this compatible solute is potentially not limited to osmoregulation but could also serve as a carbon and energy source. PMID:27597842

  4. Analytical electron microscopy of lead-free nanopowder solders

    Czech Academy of Sciences Publication Activity Database

    Buršík, Jiří; Sopoušek, J.; Zálešák, Jakub; Buršíková, V.

    Olomouc: -, 2010, s. 336-339. ISBN 978-80-87294-19-2. [NANOCON 2010. International Conference /2./. Olomouc (CZ), 12.10.2010-14.10.2010] Institutional support: RVO:68081723 Keywords : solder * nanopowder * nanoindentation Subject RIV: JG - Metallurgy

  5. Horizon shells and BMS-like soldering transformations

    OpenAIRE

    Blau, Matthias; O’Loughlin, Martin

    2016-01-01

    We revisit the theory of null shells in general relativity, with a particular emphasis on null shells placed at horizons of black holes. We study in detail the considerable freedom that is available in the case that one solders two metrics together across null hypersurfaces (such as Killing horizons) for which the induced metric is invariant under translations along the null generators. In this case the group of soldering transformations turns out to be infinite dimensional, an...

  6. Establishing a Th17 based mouse model for preclinical assessment of the toxicity of candidate microbicides

    Institute of Scientific and Technical Information of China (English)

    LI Liang-zhu; YANG Yu; YUAN Song-hua; WAN Yan-min; QIU Chao; FENG Yan-ling; XU Jian-qing; ZHANG Xiao-yan

    2010-01-01

    one mouse (score: 8), which were significantly associated with both inflammatory cytokines IL-17A and IL-6 and anti-inflammatory cytokines IL-4 and IL-10. Interestingly, IL-17A showed significant positive association with inflammatory cytokine TNF-α (r=0.739; P <0.05), anti-inflammatory cytokines IL-10 (r=0.804; P <0.01) and IL-4 (r=0.668; P <0.05).Conclusions Our data demonstrate that a panel of cytokines (IL-17A, IL-6, IL-4 and IL-10) could be used as surrogate biomarkers to predict the histopathological damage. Th17 may play a central role in orchestrating inflammatory cytokine responses. This Th17 based mouse model is cost-effective and suitable to assess the toxicity of candidate microbicides in preclinical studies.

  7. Thermomechanical fatigue behavior of Sn-Ag solder joints

    Science.gov (United States)

    Choi, S.; Subramanian, K. N.; Lucas, J. P.; Bieler, T. R.

    2000-10-01

    Microstructural studies of thermomechanically fatigued actual electronic components consisting of metallized alumina substrate and tinned copper lead, soldered with Sn-Ag or 95.5Ag/4Ag/0.5Cu solder were carried out with an optical microscope and environmental scanning electron microscope (ESEM). Damage characterization was made on samples that underwent 250 and 1000 thermal shock cycles between -40°C and 125°C, with a 20 min hold time at each extreme. Surface roughening and grain boundary cracking were evident even in samples thermally cycled for 250 times. The cracks were found to originate on the free surface of the solder joint. With increased thermal cycles these cracks grew by grain boundary decohesion. The crack that will affect the integrity of the solder joint was found to originate from the free surface of the solder very near the alumina substrate and progress towards and continue along the solder region adjacent to the Ag3Sn intermetallic layer formed with the metallized alumina substrate. Re-examination of these thermally fatigued samples that were stored at room temperature after ten months revealed the effects of significant residual stress due to such thermal cycles. Such observations include enhanced surface relief effects delineating the grain boundaries and crack growth in regions inside the joint.

  8. Life cycle assessment (LCA of lead-free solders from the environmental protection aspect

    Directory of Open Access Journals (Sweden)

    Mitovski Aleksandra M.

    2009-01-01

    Full Text Available Life-cycle assessment (LCA presents a relatively new approach, which allows comprehensive environmental consequences analysis of a product system over its entire life. This analysis is increasingly being used in the industry, as a tool for investigation of the influence of the product system on the environment, and serves as a protection and prevention tool in ecological management. This method is used to predict possible influences of a certain material to the environment through different development stages of the material. In LCA, the product systems are evaluated on a functionally equivalent basis, which, in this case, was 1000 cubic centimeters of an alloy. Two of the LCA phases, life-cycle inventory (LCA and life-cycle impact assessment (LCIA, are needed to calculate the environmental impacts. Methodology of LCIA applied in this analysis aligns every input and output influence into 16 different categories, divided in two subcategories. The life-cycle assessment reaserch review of the leadfree solders Sn-Cu, SAC (Sn-Ag-Cu, BSA (Bi-Sb-Ag and SABC (Sn-Ag-Bi-Cu respectively, is given in this paper, from the environmental protection aspect starting from production, through application process and finally, reclamation at the end-of-life, i.e. recycling. There are several opportunities for reducing the overall environmental and human health impacts of solder used in electronics manufacturing based on the results of the LCA, such as: using secondary metals reclaimed through post-industrial recycling; power consumption reducing by replacing older, less efficient reflow assembly equipment, or by optimizing the current equipment to perform at the elevated temperatures required for lead-free soldering, etc. The LCA analysis was done comparatively in relation to widely used Sn-Pb solder material. Additionally, the impact factors of material consumption, energy use, water and air reserves, human health and ecotoxicity have been ALSO considered including

  9. A PSF-based approach to Kepler/K2 data. II. Exoplanet candidates in Praesepe (M 44)

    Science.gov (United States)

    Libralato, M.; Nardiello, D.; Bedin, L. R.; Borsato, L.; Granata, V.; Malavolta, L.; Piotto, G.; Ochner, P.; Cunial, A.; Nascimbeni, V.

    2016-08-01

    In this work we keep pushing K2 data to a high photometric precision, close to that of the Kepler main mission, using a PSF-based, neighbour-subtraction technique, which also overcome the dilution effects in crowded environments. We analyse the open cluster M 44 (NGC 2632), observed during the K2 Campaign 5, and extract light curves of stars imaged on module 14, where most of the cluster lies. We present two candidate exoplanets hosted by cluster members and five by field stars. As a by-product of our investigation, we find 1680 eclipsing binaries and variable stars, 1071 of which are new discoveries. Among them, we report the presence of a heartbeat binary star. Together with this work, we release to the community a catalogue with the variable stars and the candidate exoplanets found, as well as all our raw and detrended light curves.

  10. A PSF-based approach to Kepler/K2 data. II. Exoplanet candidates in Praesepe (M 44)

    CERN Document Server

    Libralato, M; Bedin, L R; Borsato, L; Granata, V; Malavolta, L; Piotto, G; Ochner, P; Cunial, A; Nascimbeni, V

    2016-01-01

    In this work we keep pushing K2 data to a high photometric precision, close to that of the Kepler main mission, using a PSF-based, neighbour-subtraction technique, which also overcome the dilution effects in crowded environments. We analyse the open cluster M 44 (NGC 2632), observed during the K2 Campaign 5, and extract light curves of stars imaged on module 14, where most of the cluster lies. We present two candidate exoplanets hosted by cluster members and five by field stars. As a by-product of our investigation, we find 1680 eclipsing binaries and variable stars, 1071 of which are new discoveries. Among them, we report the presence of a heartbeat binary star. Together with this work, we release to the community a catalogue with the variable stars and the candidate exoplanets found, as well as all our raw and detrended light curves.

  11. Candidate evaluation system: Documentation of the data base design and application software for the prototype expert support system

    Energy Technology Data Exchange (ETDEWEB)

    Arnold, H.G.; Loffman, R.S.; Sexton, F.L.; Rush, R.M.

    1988-06-01

    The US Department of the Army established the Candidate Evaluation Prototype Project, Project Management Office to analyze the current procedure for filing Army civilian jobs and to develop improved automated procedures to meet this need. The Army Civilian Personnel Center (now the Civilian Information Directorate) tasked The Oak Ridge National Laboratory (ORNL) to provide technical support, research, and development to the Project Management Office and deliver a prototype of a Candidate Evaluation System that would run on the minicomputer hardware and software being delivered to personnel offices located throughout the world. This report discusses the background of the project, including constraints and requirements; describes the data base design and program code developed to implement the prototype; documents known limitations of the prototype; and contains recommendations to be considered in future development. The objective of this report is to document the prototype software system for use by Army programmers/analysts who will maintain or further develop the prototype software.

  12. Globular clusters hosting intermediate-mass black-holes: no mass-segregation based candidates

    CERN Document Server

    Pasquato, Mario; Sohn, Bong Won; Lee, Young-Wook

    2016-01-01

    Recently, both stellar mass-segregation and binary-fractions were uniformly measured on relatively large samples of Galactic Globular Clusters (GCs). Simulations show that both sizeable binary-star populations and Intermediate-Mass Black Holes (IMBHs) quench mass-segregation in relaxed GCs. Thus mass-segregation in GCs with a reliable binary-fraction measurement is a valuable probe to constrain IMBHs. In this paper we combine mass-segregation and binary-fraction measurements from the literature to build a sample of 33 GCs (with measured core-binary fractions), and a sample of 43 GCs (with a binary fraction measurement in the area between the core radius and the half-mass radius). Within both samples we try to identify IMBH-host candidates. These should have relatively low mass-segregation, a low binary fraction (< 5%), and short (< 1 Gyr) relaxation time. Considering the core binary fraction sample, no suitable candidates emerge. If the binary fraction between the core and the half-mass radius is consid...

  13. The Candidate

    OpenAIRE

    Osborn, John C

    2013-01-01

    ABSTRACT   The Candidate is an attempt to marry elements of journalism and gaming into a format that both entertains and educates the player. The Google-AP Scholarship, a new scholarship award that is given to several journalists a year to work on projects at the threshold of technology and journalism, funded the project. The objective in this prototype version of the game is to put the player in the shoes of a congressional candidate during an off-year election, specificall...

  14. The Reliability of Microalloyed Sn-Ag-Cu Solder Interconnections Under Cyclic Thermal and Mechanical Shock Loading

    Science.gov (United States)

    Mattila, Toni T.; Hokka, Jussi; Paulasto-Kröckel, Mervi

    2014-11-01

    In this study, the performance of three microalloyed Sn-Ag-Cu solder interconnection compositions (Sn-3.1Ag-0.52Cu, Sn-3.0Ag-0.52Cu-0.24Bi, and Sn-1.1Ag-0.52Cu-0.1Ni) was compared under mechanical shock loading (JESD22-B111 standard) and cyclic thermal loading (40 ± 125°C, 42 min cycle) conditions. In the drop tests, the component boards with the low-silver nickel-containing composition (Sn-Ag-Cu-Ni) showed the highest average number of drops-to-failure, while those with the bismuth-containing alloy (Sn-Ag-Cu-Bi) showed the lowest. Results of the thermal cycling tests showed that boards with Sn-Ag-Cu-Bi interconnections performed the best, while those with Sn-Ag-Cu-Ni performed the worst. Sn-Ag-Cu was placed in the middle in both tests. In this paper, we demonstrate that solder strength is an essential reliability factor and that higher strength can be beneficial for thermal cycling reliability but detrimental to drop reliability. We discuss these findings from the perspective of the microstructures and mechanical properties of the three solder interconnection compositions and, based on a comprehensive literature review, investigate how the differences in the solder compositions influence the mechanical properties of the interconnections and discuss how the differences are reflected in the failure mechanisms under both loading conditions.

  15. The In-Space Soldering Investigation: To Date Analysis of Experiments Conducted on the International Space Station

    Science.gov (United States)

    Grugel, Richard N.; Gillies, D. C.; Hua, F.; Anilkumar, A.

    2006-01-01

    Soldering is a well established joining and repair process that is of particular importance in the electronics industry. Still, internal solder joint defects such as porosity are prevalent and compromise desired properties such as electrical/thermal conductivity and fatigue strength. Soldering equipment resides aboard the International Space Station (ISS) and will likely accompany Exploration Missions during transit to, as well as on, the moon and Mars. Unfortunately, detrimental porosity appears to be enhanced in lower gravity environments. To this end, the In-Space Soldering Investigation (ISSI) is being conducted in the Microgravity Workbench Area (MWA) aboard the ISS as "Saturday Science" with the goal of promoting our understanding of joining techniques, shape equilibrium, wetting phenomena, and microstructural development in a microgravity environment. The work presented here will focus on direct observation of melting dynamics and shape determination in comparison to ground-based samples, with implications made to processing in other low-gravity environments. Unexpected convection effects, masked on Earth, will also be shown as well as the value of the ISS as a research platform in support of Exploration Missions.

  16. The In-Space Soldering Investigation: Research Conducted on the International Space Station in Support of NASA's Exploration Initiative

    Science.gov (United States)

    Grugel, R. N.; Fincke, M.; Sergre, P. N.; Ogle, J. A.; Funkhouser, G.; Parris, F.; Murphy, L.; Gillies, D.; Hua, F.

    2004-01-01

    Soldering is a well established joining and repair process that is of particular importance in the electronics industry. Still. internal solder joint defects such as porosity are prevalent and compromise desired properties such as electrical/thermal conductivity and fatigue strength. Soldering equipment resides aboard the International Space Station (ISS) and will likely accompany Exploration Missions during transit to, as well as on, the moon and Mars. Unfortunately, detrimental porosity appears to be enhanced in lower gravity environments. To this end, the In-Space Soldering Investigation (ISSI) is being conducted in the Microgravity Workbench Area (MWA) aboard the ISS as "Saturday Science" with the goal of promoting our understanding of joining techniques, shape equilibrium, wetting phenomena, and microstructural development in a microgravity environment. The work presented here will focus on direct observation of melting dynamics and shape determination in comparison to ground-based samples, with implications made to processing in other low-gravity environments. Unexpected convection effects, masked on Earth, will also be shown as well as the value of the ISS as a research platform in support of Exploration Missions.

  17. A recombinant, chimeric tetravalent dengue vaccine candidate based on a dengue virus serotype 2 backbone.

    Science.gov (United States)

    Osorio, Jorge E; Wallace, Derek; Stinchcomb, Dan T

    2016-04-01

    Dengue fever is caused by infection with one of four dengue virus (DENV) serotypes (DENV-1-4), necessitating tetravalent dengue vaccines that can induce protection against all four DENV. Takeda's live attenuated tetravalent dengue vaccine candidate (TDV) comprises an attenuated DENV-2 strain plus chimeric viruses containing the prM and E genes of DENV-1, -3 and -4 cloned into the attenuated DENV-2 'backbone'. In Phase 1 and 2 studies, TDV was well tolerated by children and adults aged 1.5-45 years, irrespective of prior dengue exposure; mild injection-site symptoms were the most common adverse events. TDV induced neutralizing antibody responses and seroconversion to all four DENV as well as cross-reactive T cell-mediated responses that may be necessary for broad protection against dengue fever. PMID:26635182

  18. Globular Clusters Hosting Intermediate-Mass Black Holes: No Mass-Segregation Based Candidates

    Science.gov (United States)

    Pasquato, Mario; Miocchi, Paolo; Won, Sohn Bong; Lee, Young-Wook

    2016-06-01

    Recently, both stellar mass segregation and binary fractions were uniformly measured on relatively large samples of Galactic globular clusters (GCs). Simulations show that both sizable binary-star populations and intermediate-mass black holes (IMBHs) quench mass segregation in relaxed GCs. Thus mass segregation in GCs with a reliable binary-fraction measurement is a valuable probe to constrain IMBHs. In this paper we combine mass-segregation and binary-fraction measurements from the literature to build a sample of 33 GCs (with measured core binary fractions), and a sample of 43 GCs (with binary-fraction measurements in the area between the core radius and the half-mass radius). Within both samples we try to identify IMBH-host candidates. These should have relatively low mass segregation, a low binary fraction (segregated (and show a larger binary fraction), confirming the theoretical expectation that the energy sources responsible for the large core are also quenching mass segregation.

  19. Candidate lesion-based criteria for defining a positive sacroiliac joint MRI in two cohorts of patients with axial spondyloarthritis

    DEFF Research Database (Denmark)

    Weber, Ulrich; Østergaard, Mikkel; Lambert, Robert G W;

    2015-01-01

    OBJECTIVE: To determine candidate lesion-based criteria for a positive sacroiliac joint (SIJ) MRI based on bone marrow oedema (BMO) and/or erosion in non-radiographic axial spondyloarthritis (nr-axSpA); to compare the performance of lesion-based criteria with global evaluation by expert readers...... clinical examination, pelvic radiography and laboratory values as having nr-axSpA (n=51), ankylosing spondylitis (n=34) or non-specific back pain (n=72). Four blinded readers assessed SIJ MRI, recording the presence/absence of SpA by concomitant global evaluation of T1-weighted spin echo (T1SE) and short τ...... inversion recovery (STIR) scans and, thereafter, whether BMO and/or erosion were present/absent in each SIJ quadrant of each MRI slice. We derived candidate lesion-based criteria based on the number of SIJ quadrants with BMO and/or erosion and calculated mean sensitivity and specificity for SpA. RESULTS...

  20. A new web-based data mining tool for the identification of candidate genes for human genetic disorders.

    Science.gov (United States)

    van Driel, Marc A; Cuelenaere, Koen; Kemmeren, Patrick P C W; Leunissen, Jack A M; Brunner, Han G

    2003-01-01

    To identify the gene underlying a human genetic disorder can be difficult and time-consuming. Typically, positional data delimit a chromosomal region that contains between 20 and 200 genes. The choice then lies between sequencing large numbers of genes, or setting priorities by combining positional data with available expression and phenotype data, contained in different internet databases. This process of examining positional candidates for possible functional clues may be performed in many different ways, depending on the investigator's knowledge and experience. Here, we report on a new tool called the GeneSeeker, which gathers and combines positional data and expression/phenotypic data in an automated way from nine different web-based databases. This results in a quick overview of interesting candidate genes in the region of interest. The GeneSeeker system is built in a modular fashion allowing for easy addition or removal of databases if required. Databases are searched directly through the web, which obviates the need for data warehousing. In order to evaluate the GeneSeeker tool, we analysed syndromes with known genesis. For each of 10 syndromes the GeneSeeker programme generated a shortlist that contained a significantly reduced number of candidate genes from the critical region, yet still contained the causative gene. On average, a list of 163 genes based on position alone was reduced to a more manageable list of 22 genes based on position and expression or phenotype information. We are currently expanding the tool by adding other databases. The GeneSeeker is available via the web-interface (http://www.cmbi.kun.nl/GeneSeeker/). PMID:12529706

  1. Vacuous soldering of elements of martensitic steel, grade 13-4, rotor wheels of turbocompressor

    International Nuclear Information System (INIS)

    Soldering is one of those processes, which can be profitably carried out, in vacuous furnaces. Joints soldered in an appropriate vacuum are of a very high quality due to lack of oxide inclusions, dissolved gases and blowholes. That is the reason why, while producing highly loaded parts od machines of complex selections, vacuous soldering technology appears highly competitive. Vacuous soldering of martensitic steels rotor wheals by means of BAu-4 alloy has been presented in the paper. (author)

  2. The (w)hole survey: An unbiased sample study of transition disk candidates based on Spitzer catalogs

    Science.gov (United States)

    van der Marel, N.; Verhaar, B. W.; van Terwisga, S.; Merín, B.; Herczeg, G.; Ligterink, N. F. W.; van Dishoeck, E. F.

    2016-08-01

    Understanding disk evolution and dissipation is essential for studies of planet formation. Transition disks, i.e., disks with large dust cavities and gaps, are promising candidates of active evolution. About two dozen candidates, selected by their spectral energy distribution (SED), have been confirmed to have dust cavities through millimeter interferometric imaging, but this sample is biased toward the brightest disks. The Spitzer surveys of nearby low-mass star-forming regions have resulted in more than 4000 young stellar objects. Using color criteria, we selected a sample of ~150 candidates and an additional 40 candidates and known transition disks from the literature. The Spitzer data were complemented by new observations at longer wavelengths, including new JCMT and APEX submillimeter photometry, and WISE and Herschel-PACS mid- and far-infrared photometry. Furthermore, optical spectroscopy was obtained and stellar types were derived for 85% of the sample, including information from the literature. The SEDs were fit to a grid of RADMC-3D disk models with a limited number of parameters: disk mass, inner disk mass, scale height and flaring, and disk cavity radius, where the latter is the main parameter of interest. About 72% of our targets possibly have dust cavities based on the SED. The derived cavity sizes are consistent with imaging/modeling results in the literature, where available. Trends are found with Ldisk over L∗ ratio and stellar mass and a possible connection with exoplanet orbital radii. A comparison with a previous study where color observables are used reveals large overlap between their category of planet-forming disks and our transition disks with cavities. A large number of the new transition disk candidates are suitable for follow-up observations with ALMA. Full Tables 4, 5, A.1-A.3, C.1, and D.1 are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (http://130.79.128.5) or via http://cdsarc

  3. Experimental Methods in Reduced-gravity Soldering Research

    Science.gov (United States)

    Pettegrew, Richard D.; Struk, Peter M.; Watson, John K.; Haylett, Daniel R.

    2002-01-01

    The National Center for Microgravity Research, NASA Glenn Research Center, and NASA Johnson Space Center are conducting an experimental program to explore the influence of reduced gravity environments on the soldering process. An improved understanding of the effects of the acceleration environment is important to application of soldering during current and future human space missions. Solder joint characteristics that are being considered include solder fillet geometry, porosity, and microstructural features. Both through-hole and surface mounted devices are being investigated. This paper focuses on the experimental methodology employed in this project and the results of macroscopic sample examination. The specific soldering process, sample configurations, materials, and equipment were selected to be consistent with those currently on-orbit. Other apparatus was incorporated to meet requirements imposed by operation onboard NASA's KC-135 research aircraft and instrumentation was provided to monitor both the atmospheric and acceleration environments. The contingent of test operators was selected to include both highly skilled technicians and less skilled individuals to provide a population cross-section that would be representative of the skill mix that might be encountered in space mission crews.

  4. High-Temperature Lead-Free Solder Alternatives: Possibilities and Properties

    DEFF Research Database (Denmark)

    High-temperature solders have been widely used as joining materials to provide stable interconnections that resist a severe thermal environment and also to facilitate the drive for miniaturization. High-lead containing solders have been commonly used as high-temperature solders. The development of...

  5. 30 CFR 77.1112 - Welding, cutting, or soldering with arc or flame; safeguards.

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Welding, cutting, or soldering with arc or... WORK AREAS OF UNDERGROUND COAL MINES Fire Protection § 77.1112 Welding, cutting, or soldering with arc or flame; safeguards. (a) When welding, cutting, or soldering with arc or flame near...

  6. 30 CFR 75.1106 - Welding, cutting, or soldering with arc or flame underground.

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Welding, cutting, or soldering with arc or... Protection § 75.1106 Welding, cutting, or soldering with arc or flame underground. All welding, cutting, or... conducted in fireproof enclosures. Welding, cutting, or soldering with arc or flame in other than...

  7. 30 CFR 77.1916 - Welding, cutting, and soldering; fire protection.

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Welding, cutting, and soldering; fire... OF UNDERGROUND COAL MINES Slope and Shaft Sinking § 77.1916 Welding, cutting, and soldering; fire protection. (a) One portable fire extinguisher shall be provided where welding, cutting, or soldering...

  8. Identification of candidate target genes of pituitary adenomas based on the DNA microarray.

    Science.gov (United States)

    Zhou, Wei; Ma, Chun-Xiao; Xing, Ya-Zhou; Yan, Zhao-Yue

    2016-03-01

    The present study aimed to explore molecular mechanisms involved in pituitary adenomas (PAs) and to discover target genes for their treatment. The gene expression profile GSE4488 was downloaded from the Gene Expression Omnibus database. Differentially expressed genes (DEGs) were identified using the Limma package and analyzed by two‑dimensional hierarchical clustering. Gene ontology (GO) and pathway enrichment analyses were performed in order to investigate the functions of DEGs. Subsequently, the protein‑protein interaction (PPI) network was constructed using Cytoscape software. DEGs were then mapped to the connectivity map database to identify molecular agents associated with the underlying mechanisms of PAs. A total of 340 upregulated and 49 downregulated DEGs in PA samples compared with those in normal controls were identified. Hierarchical clustering analysis showed that DEGs were highly differentially expressed, indicating their aptness for distinguishing PA samples from normal controls. Significant gene ontology terms were positive regulation of immune system-associated processes for downregulated DEGs and skeletal system development for upregulated DEGs. Pathways significantly enriched by DEGs included extracellular matrix (ECM)‑receptor interaction, the Hedgehog (Hh) signaling pathway and neuroactive ligand‑receptor interaction. The PPI network was constructed with 117 nodes, 123 edges and CD44 and Gli2 as hub nodes. Furthermore, depudecin, a small molecule drug, was identified to be mechanistically associated with PA. The genes CD44 and Gli2 have important roles in the progression of PAs via ECM‑receptor interaction and the Hh signaling pathway and are therefore potential target genes of PA. In addition, depudecin may be a candidate drug for the treatment of PAs. PMID:26782791

  9. An Overview of Surface Finishes and Their Role in Printed Circuit Board Solderability and Solder Joint Performance

    Energy Technology Data Exchange (ETDEWEB)

    Vianco, P.T.

    1998-10-15

    A overview has been presented on the topic of alternative surface finishes for package I/Os and circuit board features. Aspects of processability and solder joint reliability were described for the following coatings: baseline hot-dipped, plated, and plated-and-fused 100Sn and Sn-Pb coatings; Ni/Au; Pd, Ni/Pd, and Ni/Pd/Au finishes; and the recently marketed immersion Ag coatings. The Ni/Au coatings appear to provide the all-around best option in terms of solderability protection and wire bondability. Nickel/Pal ftishes offer a slightly reduced level of performance in these areas that is most likely due to variable Pd surface conditions. It is necessmy to minimize dissolved Au or Pd contents in the solder material to prevent solder joint embrittlement. Ancillary aspects that included thickness measurement techniques; the importance of finish compatibility with conformal coatings and conductive adhesives; and the need for alternative finishes for the processing of non-Pb bearing solders were discussed.

  10. Corrosion Issues in Solder Joint Design and Service

    Energy Technology Data Exchange (ETDEWEB)

    VIANCO,PAUL T.

    1999-11-24

    Corrosion is an important consideration in the design of a solder joint. It must be addressed with respect to the service environment or, as in the case of soldered conduit, as the nature of the medium being transported within piping or tubing. Galvanic-assisted corrosion is of particular concern, given the fact that solder joints are comprised of different metals or alloy compositions that are in contact with one-another. The (thermodynamic) potential for corrosion to take place in a particular environment requires the availability of the galvanic series for those conditions and which includes the metals or alloys in question. However, the corrosion kinetics, which actually determine the rate of material loss under the specified service conditions, are only available through laboratory evaluations or field data that are found in the existing literature or must be obtained by in-house testing.

  11. Horizon Shells and BMS-like Soldering Transformations

    CERN Document Server

    Blau, Matthias

    2015-01-01

    We revisit the theory of null shells in general relativity, with a particular emphasis on null shells placed at horizons of black holes. We study in detail the considerable freedom that is available in the case that one solders two metrics together across null hypersurfaces (such as Killing horizons) for which the induced metric is invariant under translations along the null generators. In this case the group of soldering transformations turns out to be infinite dimensional, and these solderings create non-trivial horizon shells containing both massless matter and impulsive gravitational wave components. We also rephrase this result in the language of Carrollian symmetry groups. To illustrate this phenomenon we discuss in detail the example of shells on the horizon of the Schwarzschild black hole (with equal interior and exterior mass), uncovering a rich classical structure at the horizon and deriving an explicit expression for the general horizon shell energy-momentum tensor. In the special case of BMS-like ...

  12. Tsunami-HySEA: A GPU based model for the Italian candidate Tsunami Service Provider

    Science.gov (United States)

    Gonzalez Vida, Jose Manuel; Macias, Jorge; Castro, Manuel; de la Asuncion, Marc; Melini, Daniele; Romano, Fabrizio; Tonini, Roberto; Lorito, Stefano; Piatanesi, Alessio; Molinari, Irene

    2015-04-01

    Tsunami Service Providers (TSP), providing tsunami warnings in the framework of the systems coordinated by IOC/UNESCO worldwide, and other national tsunami warning centers, are striving to complement, or replace, decision matrices and pre-calculated tsunami scenario databases with FTRT (Faster Than Real Time) tsunami simulations. The aim is to increase the accuracy of tsunami forecast by assimilating the largest possible amount of data in quasi real time, and performing simulations in a few minutes wall-clock time, possibly including the coastal inundation stage. This strategy of direct real time computation, that could seem unfeasible a decade ago, it is now foreseeable thanks to the astonishingly recent increase in the computational power and bandwidth evolution of modern GPUs. The INGV in collaboration with the EDANYA Group (University of Málaga) are developing and implementing a FTRT Tsunami Simulation approach for the Italian candidate TSP, namely the Centro Allerta Tsunami (CAT), which is in pre-operational stage starting from 1 October 2014, in the 24/7 seismic monitoring room at INGV. The mandate of CAT is to provide warnings for potential tsunamis within the Mediterranean basin to its subscribers, in the framework of NEAMTWS (http://www.ioc-tsunami.org/index.php?option=com_content&view=article&id=70:neamtws-home&catid=9&Itemid=14&lang=es). CAT also performs global monitoring, for continuous testing, training, and validation purposes. The tsunami-HySEA model, developed by EDANYA Group, implements in the same code the three phases of an earthquake generated tsunami: generation, propagation and coastal inundation. At the same time it is implemented in nested meshes with different resolution and multi-GPU environment, which allows much faster than real time simulations. The challenge set by the Italian TSP for warning in the NEAMTWS region is twofold: to be able to reasonably constrain the earthquake source in the absence of deep sea tsunami sensors, and to

  13. Recognition-Based Pedagogy: Teacher Candidates' Experience of Deficit

    Science.gov (United States)

    Parkison, Paul T.; DaoJensen, Thuy

    2014-01-01

    This study seeks to introduce what we call "recognition-based pedagogy" as a conceptual frame through which teachers and instructors can collaboratively develop educative experiences with students. Recognition-based pedagogy connects the theories of critical pedagogy, identity politics, and the politics of recognition with the educative…

  14. A solder sealing method for paraffin-filled microcavities

    OpenAIRE

    Nguyen, Hugo; Bejhed, Johan; Köhler, Johan; Thornell, Greger

    2006-01-01

    Demonstrated and investigated here is a method to seal microfluidic systems by soldering. As a particularly difficult case of growing importance, the sealing of openings contaminated with paraffin wax was studied. Solder paste, screen printed on a metallized silicon, substrate was melted locally through application of 6.5 to 10 V to a 5 Ω copper film resistor for a few seconds and found able to drive an intermediate layer of paraffin away and seal a 0.2 mm diameter circular via by wetti...

  15. Characterization of microstructure and phases in lead-free solder alloys

    International Nuclear Information System (INIS)

    Significant progress has been made in the development of a range of lead-free solder alloys for application in household appliances, IT, telecommunication and other electronic equipment. The choice of a lead-free solder may however depend on the final requirement and operating conditions. In this work, lead-free solder (Sn-Bi) alloys have been developed to examine the structural characteristics of the solder joints made under different conditions. The results of microstructural and interfacial changes occurring during aging are presented in order to optimize composition and processing parameters of the solder alloys. (author)

  16. Evaluation of Candidate Measures for Home-Based Screening of Sleep Disordered Breathing in Taiwanese Bus Drivers

    Directory of Open Access Journals (Sweden)

    Hua Ting

    2014-05-01

    Full Text Available Background: Sleepiness-at-the-wheel has been identified as a major cause of highway accidents. The aim of our study is identifying the candidate measures for home-based screening of sleep disordered breathing in Taiwanese bus drivers, instead of polysomnography. Methods: Overnight polysomnography accompanied with simultaneous measurements of alternative screening devices (pulse oximetry, ApneaLink, and Actigraphy, heart rate variability, wake-up systolic blood pressure and questionnaires were completed by 151 eligible participants who were long-haul bus drivers with a duty period of more than 12 h a day and duty shifting. Results: 63.6% of professional bus drivers were diagnosed as having sleep disordered breathing and had a higher body mass index, neck circumference, systolic blood pressure, arousal index and desaturation index than those professional bus drivers without evidence of sleep disordered breathing. Simple home-based candidate measures: (1 Pulse oximetry, oxygen-desaturation indices by ≥3% and 4% (r = 0.87~0.92; (2 Pulse oximetry, pulse-rising indices by ≥7% and 8% from a baseline (r = 0.61~0.89; and (3 ApneaLink airflow detection, apnea-hypopnea indices (r = 0.70~0.70, based on recording-time or Actigraphy-corrected total sleep time were all significantly correlated with, and had high agreement with, corresponding polysomnographic apnea-hypopnea indices [(1 94.5%~96.6%, (2 93.8%~97.2%, (3 91.1%~91.3%, respectively]. Conversely, no validities of SDB screening were found in the multi-variables apnea prediction questionnaire, Epworth Sleepiness Scale, night-sleep heart rate variability, wake-up systolic blood pressure and anthropometric variables. Conclusions: The indices of pulse oximetry and apnea flow detection are eligible criteria for home-based screening of sleep disordered breathing, specifically for professional drivers.

  17. Application of a kernel-based online learning algorithm to the classification of nodule candidates in computer-aided detection of CT lung nodules

    International Nuclear Information System (INIS)

    Classification of the nodule candidates in computer-aided detection (CAD) of lung nodules in CT images was addressed by constructing a nonlinear discriminant function using a kernel-based learning algorithm called the kernel recursive least-squares (KRLS) algorithm. Using the nodule candidates derived from the processing by a CAD scheme of 100 CT datasets containing 253 non-calcified nodules or 3 mm or larger as determined by the consensus of two thoracic radiologists, the following trial were carried out 100 times: by randomly selecting 50 datasets for training, a nonlinear discriminant function was obtained using the nodule candidates in the training datasets and tested with the remaining candidates; for comparison, a rule-based classification was tested in a similar manner. At the number of false positives per case of about 5, the nonlinear classification method showed an improved sensitivity of 80% (mean over the 100 trials) compared with 74% of the rule-based method. (orig.)

  18. Potential and limits of water cooled divertor concepts based on monoblock design as possible candidates for a DEMO reactor

    Energy Technology Data Exchange (ETDEWEB)

    Li-Puma, Antonella, E-mail: antonella.lipuma@cea.fr [CEA, DEN, Saclay, DM2S, SERMA, F-91191 Gif-sur-Yvette (France); Richou, Marianne; Magaud, Philippe; Missirlian, Marc [CEA, IRFM, F-13108 Saint Paul Lez Durance (France); Visca, Eliseo [Associazione EURATOM-ENEA sulla Fusione, C.R. Frascati, IT-00044 Frascati (Italy); Ridolfini, Vincenzo Pericoli [EFDA-CSU Garching, PPPT department, D-85748 Garching bei München (Germany)

    2013-10-15

    In this paper water-cooled divertor concepts based on tungsten monoblock design identified in previous studies as candidate for fusion power plant have been reviewed to assess their potential and limits as possible candidates for a DEMO concept deliverable in a short to medium term (“conservative baseline design”). The rationale and technology development assumptions that have led to their selection are revisited taking into account present factual information on reactor parameters, materials properties and manufacturing technologies. For that purpose, main parameters impacting the divertor design are identified and their relevance discussed. The state of the art knowledge on materials and relevant manufacturing techniques is reviewed. Particular attention is paid to material properties change after irradiation; phenomenon thresholds (if any) and possible operating ranges are identified (in terms of temperature and damage dose). The suitability of various proposed heat sink/structural and sacrificial layer materials, as proposed in the past, are re-assessed (e.g. with regard to the possibility of reducing peak heat flux and/or neutron radiation damages). As a result, potential and limits of various proposed concepts are highlighted, ranges in which they could operate (if any) defined and possible improvements are proposed. Identified missing point in materials database and/or manufacturing techniques knowledge that should be uppermost investigated in future R and D activities are reported. This work has been carried out in the frame of EFDA PPPT Work Programme activities.

  19. Potential and limits of water cooled divertor concepts based on monoblock design as possible candidates for a DEMO reactor

    International Nuclear Information System (INIS)

    In this paper water-cooled divertor concepts based on tungsten monoblock design identified in previous studies as candidate for fusion power plant have been reviewed to assess their potential and limits as possible candidates for a DEMO concept deliverable in a short to medium term (“conservative baseline design”). The rationale and technology development assumptions that have led to their selection are revisited taking into account present factual information on reactor parameters, materials properties and manufacturing technologies. For that purpose, main parameters impacting the divertor design are identified and their relevance discussed. The state of the art knowledge on materials and relevant manufacturing techniques is reviewed. Particular attention is paid to material properties change after irradiation; phenomenon thresholds (if any) and possible operating ranges are identified (in terms of temperature and damage dose). The suitability of various proposed heat sink/structural and sacrificial layer materials, as proposed in the past, are re-assessed (e.g. with regard to the possibility of reducing peak heat flux and/or neutron radiation damages). As a result, potential and limits of various proposed concepts are highlighted, ranges in which they could operate (if any) defined and possible improvements are proposed. Identified missing point in materials database and/or manufacturing techniques knowledge that should be uppermost investigated in future R and D activities are reported. This work has been carried out in the frame of EFDA PPPT Work Programme activities

  20. Problem-Based Learning in the Educational Psychology Classroom: Bahraini Teacher Candidates' Experience

    Science.gov (United States)

    Razzak, Nina Abdul

    2012-01-01

    There was a concern from faculty at Bahrain Teachers' College that undergraduate Bahraini students lack the necessary competencies needed for success in educational contexts that are conducive to active, student-centered learning. It was decided that the students be introduced to a problem-based learning (PBL) strategy in one of their educational…

  1. Usability of a Web-Based School Experience System: Opinions of IT Teachers and Teacher Candidates

    Science.gov (United States)

    Genç, Zülfü

    2015-01-01

    With advances in information and communication technologies, the classical nature of educational institutions has changed. One innovative effort within teacher training is the Web-Based School Experience System (WBSES) developed by the researcher. In this study, the usability of an existing WBSES is evaluated from both teachers' (n = 13) and…

  2. Soldering and brazing safety guide: A handbook on space practice for those involved in soldering and brazing

    Science.gov (United States)

    This manual provides those involved in welding and brazing with effective safety procedures for use in performance of their jobs. Hazards exist in four types of general soldering and brazing processes: (1) cleaning; (2) application of flux; (3) application of heat and filler metal; and (4) residue cleaning. Most hazards during those operations can be avoided by using care, proper ventilation, protective clothing and equipment. Specific process hazards for various methods of brazing and soldering are treated. Methods to check ventilation are presented as well as a check of personal hygiene and good maintenance practices are stressed. Several emergency first aid treatments are described.

  3. Fast Qualification of Solder Reliability in Solid-state Lighting System

    OpenAIRE

    Zhang, J.

    2015-01-01

    Solid-state lighting (SSL), which is based 0n semiconductor Lighting Emitting Diode (LED), is the most promising and reliable energy saving solution for future lighting applications. Since a bare LED die can hardly survive without a package, one of the most import function of the LED package is to facilitate the electrical connection and heat dissipation of the light engine mounted on a printed circuit board (PCB) by Land Grid Array (LGA) solder joints. These joints have been proven to be one...

  4. Thermal cyclic test for Sn-4Ag-0.5Cu solders on high P Ni/Au and Ni/Pd/Au surface finishes

    Directory of Open Access Journals (Sweden)

    M.A. Azmah Hanim

    2015-12-01

    Full Text Available In electronic packaging, the reliability of the interconnection changes with the surface finish and the type of solders being used. Thermal cycling is one method of reliability assessment. In thermal cycling experiments, the strain state is simplified by soldering together regular shaped pieces of materials with different coefficients of thermal expansion and exposing the joint to repeated fluctuations of temperature within a certain range. Thus, this study focuses on the intermetallic evolution of Sn-4Ag-0.5Cu on Ni/Au and Ni/Pd/Au surface finishes with thermal cycling up to 1000 cycles with the range of temperature varying from 10 to 80 °C. Sandwich samples were prepared by placing solder balls of Sn-4Ag-0.5Cu between two substrates of two different surface finishes: Ni/Au and Ni/Pd/Au. Optical microscope and FESEM (Field emission scanning electron microscope were used to analyze the samples. From the study, it was observed that the intermetallic changes from (Cu, Ni6Sn5 to (Ni, Cu3Sn4 after 1000 thermal cycles for Ni/Au. These changes promote the formation of cracks at the solder joint because of the different mechanical properties between Ni-Sn based intermetallic and Cu-Sn intermetallics. However, for the Ni/Pd/Au surface finishes, no cracks formed after thermal cycling up to 1000 cycles. This shows that the reliability of the solder joint is higher for Ni/Pd/Au surface finishes in this experiment. Based on these results, it can be concluded that the reliability of the Ni/Pd/Au surface finishes with Sn-4Ag-0.5Cu solders is higher within the given condition of this research.

  5. Amplicon-based metagenomics identified candidate organisms in soils that caused yield decline in strawberry.

    Science.gov (United States)

    Xu, Xiangming; Passey, Thomas; Wei, Feng; Saville, Robert; Harrison, Richard J

    2015-01-01

    A phenomenon of yield decline due to weak plant growth in strawberry was recently observed in non-chemo-fumigated soils, which was not associated with the soil fungal pathogen Verticillium dahliae, the main target of fumigation. Amplicon-based metagenomics was used to profile soil microbiota in order to identify microbial organisms that may have caused the yield decline. A total of 36 soil samples were obtained in 2013 and 2014 from four sites for metagenomic studies; two of the four sites had a yield-decline problem, the other two did not. More than 2000 fungal or bacterial operational taxonomy units (OTUs) were found in these samples. Relative abundance of individual OTUs was statistically compared for differences between samples from sites with or without yield decline. A total of 721 individual comparisons were statistically significant - involving 366 unique bacterial and 44 unique fungal OTUs. Based on further selection criteria, we focused on 34 bacterial and 17 fungal OTUs and found that yield decline resulted probably from one or more of the following four factors: (1) low abundance of Bacillus and Pseudomonas populations, which are well known for their ability of supressing pathogen development and/or promoting plant growth; (2) lack of the nematophagous fungus (Paecilomyces species); (3) a high level of two non-specific fungal root rot pathogens; and (4) wet soil conditions. This study demonstrated the usefulness of an amplicon-based metagenomics approach to profile soil microbiota and to detect differential abundance in microbes. PMID:26504572

  6. Amplicon-based metagenomics identified candidate organisms in soils that caused yield decline in strawberry

    OpenAIRE

    Xiangming Xu; Thomas Passey; Feng Wei; Robert Saville; Harrison, Richard J.

    2015-01-01

    A phenomenon of yield decline due to weak plant growth in strawberry was recently observed in non-chemo-fumigated soils, which was not associated with the soil fungal pathogen Verticillium dahliae, the main target of fumigation. Amplicon-based metagenomics was used to profile soil microbiota in order to identify microbial organisms that may have caused the yield decline. A total of 36 soil samples were obtained in 2013 and 2014 from four sites for metagenomic studies; two of the four sites ha...

  7. Discovery and characterization of antibody variants using mass spectrometry-based comparative analysis for biosimilar candidates of monoclonal antibody drugs.

    Science.gov (United States)

    Li, Wenhua; Yang, Bin; Zhou, Dongmei; Xu, Jun; Ke, Zhi; Suen, Wen-Chen

    2016-07-01

    Liquid chromatography mass spectrometry (LC-MS) is the most commonly used technique for the characterization of antibody variants. MAb-X and mAb-Y are two approved IgG1 subtype monoclonal antibody drugs recombinantly produced in Chinese hamster ovary (CHO) cells. We report here that two unexpected and rare antibody variants have been discovered during cell culture process development of biosimilars for these two approved drugs through intact mass analysis. We then used comprehensive mass spectrometry-based comparative analysis including reduced light, heavy chains, and domain-specific mass as well as peptide mapping analysis to fully characterize the observed antibody variants. The "middle-up" mass comparative analysis demonstrated that the antibody variant from mAb-X biosimilar candidate was caused by mass variation of antibody crystalline fragment (Fc), whereas a different variant with mass variation in antibody antigen-binding fragment (Fab) from mAb-Y biosimilar candidate was identified. Endoproteinase Lys-C digested peptide mapping and tandem mass spectrometry analysis further revealed that a leucine to glutamine change in N-terminal 402 site of heavy chain was responsible for the generation of mAb-X antibody variant. Lys-C and trypsin coupled non-reduced and reduced peptide mapping comparative analysis showed that the formation of the light-heavy interchain trisulfide bond resulted in the mAb-Y antibody variant. These two cases confirmed that mass spectrometry-based comparative analysis plays a critical role for the characterization of monoclonal antibody variants, and biosimilar developers should start with a comprehensive structural assessment and comparative analysis to decrease the risk of the process development for biosimilars. PMID:27214604

  8. The COST 531 Thermodynamic Database for Lead-free Solders

    Czech Academy of Sciences Publication Activity Database

    Watson, A.; Dinsdale, A.; Kroupa, Aleš; Vřešťál, J.; Zemanová, Adéla

    Helsinki : Helsinki University of Technology, 2008 . s. 78-78. [CALPHAD /37./. 15.06. 2008 -20.08. 2008 , Saariselkä] Institutional research plan: CEZ:AV0Z20410507 Keywords : COST 531 * lead-free solder materials Subject RIV: BJ - Thermodynamics

  9. Aqueous cleaning of flux residue from solder joints. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Krska, C.M.

    1992-08-01

    Solder joints have traditionally been cleaned using chlorinated or fluorinated solvents. This study addressed alternate processing. One process involved using a saponifier/water solution to remove rosin flux residues; the other process involved using a water-soluble flux and water to remove the residues. Although both processes were satisfactory, the water-soluble flux with water cleaning proved to be the best.

  10. Aqueous cleaning of flux residue from solder joints

    Energy Technology Data Exchange (ETDEWEB)

    Krska, C.M.

    1992-08-01

    Solder joints have traditionally been cleaned using chlorinated or fluorinated solvents. This study addressed alternate processing. One process involved using a saponifier/water solution to remove rosin flux residues; the other process involved using a water-soluble flux and water to remove the residues. Although both processes were satisfactory, the water-soluble flux with water cleaning proved to be the best.

  11. Horizon shells and BMS-like soldering transformations

    Science.gov (United States)

    Blau, Matthias; O'Loughlin, Martin

    2016-03-01

    We revisit the theory of null shells in general relativity, with a particular emphasis on null shells placed at horizons of black holes. We study in detail the considerable freedom that is available in the case that one solders two metrics together across null hypersurfaces (such as Killing horizons) for which the induced metric is invariant under translations along the null generators. In this case the group of soldering transformations turns out to be infinite dimensional, and these solderings create non-trivial horizon shells containing both massless matter and impulsive gravitational wave components. We also rephrase this result in the language of Carrollian symmetry groups. To illustrate this phenomenon we discuss in detail the example of shells on the horizon of the Schwarzschild black hole (with equal interior and exterior mass), uncovering a rich classical structure at the horizon and deriving an explicit expression for the general horizon shell energy-momentum tensor. In the special case of BMS-like soldering supertranslations we find a conserved shell-energy that is strikingly similar to the standard expression for asymptotic BMS supertranslation charges, suggesting a direct relation between the physical properties of these horizon shells and the recently proposed BMS supertranslation hair of a black hole.

  12. New types of lead-free solders and their properties

    Czech Academy of Sciences Publication Activity Database

    Drápala, J.; Petlák, D.; Malcharcziková, J.; Vodárek, V.; Konečná, K.; Smetana, B.; Zlá, S.; Kostiuková, G.; Seidlerová, J.; Lasek, S.; Madaj, M.; Kroupa, Aleš; Urbánek, J.; Dušek, K.; Sedláček, J.; Sidorov, V.E.

    Ostrava: TANGER LTD, 2012, s. 1455-1466. ISBN 978-80-87294-31-4. [Metal 2012. Brno (CZ), 23.05.2012-25.05.2012] R&D Projects: GA MŠk(CZ) OC08053 Institutional support: RVO:68081723 Keywords : lead-free solders * experimental measurements * ternary and binary systems Subject RIV: BJ - Thermodynamics

  13. Green electronics through Legislation and lead free soldering

    Energy Technology Data Exchange (ETDEWEB)

    Herat, Sunil [Griffith School of Engineering, Griffith University, Queensland (Australia)

    2008-02-15

    Management of used electrical and electronic equipment (EEE) is becoming a major issue as each year around 20 to 50 million tonnes of electronic waste (e-waste) is generated worldwide. EEE contains over 1000 materials of which lead (Pb) has been one of the targets of the regulators forcing manufacturers to adopt lead free products. Industry has come up with several lead free solders with preference given to alloys containing tin, silver, and copper but there is no,drop-in' substitute to leaded solder. Issues with lead free solders such as temperature, intermetallics, tin whisker, tin pest, and reliability are yet to be resolved. The paper investigated the contribution of lead free soldering to green electronics in a holistic way. Global lead free movement has reached a point of no return. However, it is necessary to make sure that life span of EEE is not shortened thereby resulting in an unforeseen increase in e-waste or problem shifting does not occur by shifting a problem from one life cycle to another or from one category/media to another. (Abstract Copyright [2008], Wiley Periodicals, Inc.)

  14. Interfacial reaction and elemental redistribution in Sn3.0Ag0.5Cu-xPd/immersion Au/electroless Ni solder joints after aging

    Energy Technology Data Exchange (ETDEWEB)

    Wang, I-Tai [Department of Material Science and Engineering, National Tsing Hua University, Hsinchu, Taiwan (China); Duh, Jenq-Gong, E-mail: jgd@mx.nthu.edu.tw [Department of Material Science and Engineering, National Tsing Hua University, Hsinchu, Taiwan (China); Cheng, Chih-Yuan; Wang, Jim [Shenmao Technology Inc. Micro Material Institute, Taoyuan, Taiwan (China)

    2012-02-15

    Highlights: Black-Right-Pointing-Pointer Pd doping has significant effect on the microstructural development of Sn3.0Ag0.5Cu solder. Black-Right-Pointing-Pointer The growth of intermetallics reduced by adding Pd. Black-Right-Pointing-Pointer Pd mainly dissolved in Cu{sub 6}Sn{sub 5}. Black-Right-Pointing-Pointer Adding Pd into the solder improves stability of the intermetallics. - Abstract: Sn3.0Ag0.5Cu solder doped with 0, 100, and 500 ppm Pd was reflowed with electroless Ni/immersion Au substrate. As Pd concentration increased in the solder, formation and growth of (Cu,Ni){sub 6}Sn{sub 5} were suppressed. After thermal aging, Cu{sub 4}Ni{sub 2}Sn{sub 5} and Cu{sub 5}NiSn{sub 5} were observed at interface of Sn3.0Ag0.5Cu-xPd/Au/Ni systems. As compared to Cu{sub 4}Ni{sub 2}Sn{sub 5}, more Pd dissolved in Cu{sub 5}NiSn{sub 5}. In addition, Pd doping enhanced the growth of Cu{sub 4}Ni{sub 2}Sn{sub 5} and slowed the formation of Cu{sub 5}NiSn{sub 5}, which would stabilize the intermetallic compound. Based on quantitative analysis by field emission electron probe microanalyzer, the correlation between Pd doping and elemental redistribution in solder joints was probed and discussed. This study described a possible mechanism of the formation of different intermetallic compounds in Pd-doped lead-free solder.

  15. Interfacial reaction and IMC growth between Bi-containing Sn0.7Cu solders and Cu substrate during soldering and aging

    International Nuclear Information System (INIS)

    Highlights: • The Bi-containing Sn0.7Cu/Cu soldered joints were prepared by reflowing. • Growth of the interfacial IMC layer was accelerated by Bi addition. • The interfacial IMC layer were thicker with higher Bi content in solder alloy. -- Abstract: Intermetallic compounds (IMCs) formations of Bi-containing Sn0.7Cu/Cu interface were studied for soldering at four levels of temperatures (240, 260, 280 and 300 °C) and isothermal aging at 150 °C. It was found that addition of Bi into the Sn0.7Cu eutectic solder caused the excessive formations of IMCs during the soldering reaction and thereafter in aging condition. The interfacial IMC layer was composed of Cu6Sn5 and Cu3Sn layers after liquid soldering for Sn0.7Cu/Cu, Sn0.7Cu0.7Bi/Cu and Sn0.7Cu1.3Bi/Cu joints. With the increasing soldering temperature, the thickness of IMC layers (including Cu6Sn5 and Cu3Sn IMCs) increased linearly. After various days of aging, a comparatively planar IMC layer at the solder/Cu interface was observed than that of the as-soldered joints. The growth of IMC layer during aging for Sn0.7Cu, Sn0.7Cu0.7Bi and Sn0.7Cu1.3Bi solders followed the diffusion control mechanism. And the interfacial IMC layers were thicker with higher Bi content in solder alloy since the Bi could result in more chemical bonds between Cu atoms or between Cu and Sn atoms to be broken, which made more Cu and Sn atoms activated

  16. A malaria diagnostic tool based on computer vision screening and visualization of Plasmodium falciparum candidate areas in digitized blood smears.

    Directory of Open Access Journals (Sweden)

    Nina Linder

    Full Text Available INTRODUCTION: Microscopy is the gold standard for diagnosis of malaria, however, manual evaluation of blood films is highly dependent on skilled personnel in a time-consuming, error-prone and repetitive process. In this study we propose a method using computer vision detection and visualization of only the diagnostically most relevant sample regions in digitized blood smears. METHODS: Giemsa-stained thin blood films with P. falciparum ring-stage trophozoites (n = 27 and uninfected controls (n = 20 were digitally scanned with an oil immersion objective (0.1 µm/pixel to capture approximately 50,000 erythrocytes per sample. Parasite candidate regions were identified based on color and object size, followed by extraction of image features (local binary patterns, local contrast and Scale-invariant feature transform descriptors used as input to a support vector machine classifier. The classifier was trained on digital slides from ten patients and validated on six samples. RESULTS: The diagnostic accuracy was tested on 31 samples (19 infected and 12 controls. From each digitized area of a blood smear, a panel with the 128 most probable parasite candidate regions was generated. Two expert microscopists were asked to visually inspect the panel on a tablet computer and to judge whether the patient was infected with P. falciparum. The method achieved a diagnostic sensitivity and specificity of 95% and 100% as well as 90% and 100% for the two readers respectively using the diagnostic tool. Parasitemia was separately calculated by the automated system and the correlation coefficient between manual and automated parasitemia counts was 0.97. CONCLUSION: We developed a decision support system for detecting malaria parasites using a computer vision algorithm combined with visualization of sample areas with the highest probability of malaria infection. The system provides a novel method for blood smear screening with a significantly reduced need for

  17. Substituição das soldas estanho-chumbo na manufatura: efeitos na saúde do trabalhador e no desempenho ambiental Substitution of tin-lead solders in manufacturing: impacts on workers' health and on the environment

    Directory of Open Access Journals (Sweden)

    Cecilia Maria Villas Bôas de Almeida

    2013-03-01

    Full Text Available As soldas à base de estanho-chumbo (63Sn/37Pb são largamente utilizadas no Brasil e no mundo. Este estudo aplica a avaliação em emergia em um fabricante de soldas brandas à base de estanho e chumbo e outros metais. O cálculo da emergia por unidade de três tipos de solda mostra que mais recursos são utilizados para produzir uma tonelada de soldas livres de chumbo do que para produzir soldas à base de estanho e chumbo. O indicador DALY (Disability Adjusted Life Years foi utilizado para comparar as emissões na atmosfera dos três tipos de produção de soldas e os resultados apontam para a adoção das soldas à base de chumbo, quando se considera todo o ciclo de vida do produto. A diferença entre os resultados obtidos por avaliações locais e globais é discutida.Tin-lead solders (Sn63-Pb37 have been widely used in Brazil and worldwide. This study evaluates the emergy in a company that manufactures soft solders based on tin, lead, and other metals. The calculation of emergy per unit of three types of solder showed that more resources are used to produce one ton of lead-free solders than those used to produce tin-lead solders. The DALY (Disability Adjusted Life Years indicator was used to assess the emissions to air of three types of solder. The results favor the use of tin-lead solders when the whole product life-cycle is evaluated. The difference between the results obtained by local and global assessments is discussed.

  18. Accomplishing PETE Learning Standards and Program Accreditation through Teacher Candidates' Technology-Based Service Learning Projects

    Science.gov (United States)

    Gibbone, Anne; Mercier, Kevin

    2014-01-01

    Teacher candidates' use of technology is a component of physical education teacher education (PETE) program learning goals and accreditation standards. The methods presented in this article can help teacher candidates to learn about and apply technology as an instructional tool prior to and during field or clinical experiences. The goal in…

  19. Solid-state Diffusion Bonding of Candidate Fe-base and Ni-base Alloys for the Application of S-CO2 Cycle Heat Exchanger

    International Nuclear Information System (INIS)

    To achieve efficient heat transfer, compact type heat exchangers, such as printed circuit or plate fin type heat exchanger, are considered for intermediate heat exchangers (IHXs). Solid-state diffusion bonding (DB) is one of key issues for joining the thin metal sheets with flow passages that are either machined or photo-chemically etched. In this study, diffusion bonding was performed for the candidate Fe-base and Ni-base alloys. Tensile properties of the as-bonded were compared with the as-received and characteristics of the aged in high temperature S-CO2 environment were discussed. Studies on diffusion bonding of candidate alloys for the application of super-critical CO2 cycle were carried out. Strength ratios were close to 1 for Fe-base alloys (F91, SS 316H, and SS 347H), while those of Ni-base alloys (Alloy 600, Alloy 690) and Fe-Ni-Cr alloy (Incoloy 800HT) were somewhat decreased to about 0.8 due to the planar grain boundary and precipitates formed along the bond-line. After exposure in high temperature S-CO2 environment for 1000 h, mechanical properties were not changed substantially and the location of the failure was still in the gauge section away from the bond-line for most alloys. Thus, bond-line which plays a role as grain boundary is thought to have superior corrosion and carburization resistance comparable to that of parent matrix

  20. Development of materials design tool and its application in Pb-free micro-solders in electronic package

    Institute of Scientific and Technical Information of China (English)

    OHNUMA; Ikuo; KAINUMA; Ryosuke; ISHIDA; Kiyohito; CHANG; Austin; Y.

    2010-01-01

    A materials design tool for developing Pb-free soldering alloys in electronic package was developed based on comprehensive experimental data of phase equilibria and thermodynamic properties data accumulated with the CALPHAD (calculation of phase diagrams) method and contains 10 elements,namely,Ag,Au,Bi,Cu,In,Ni,Sb,Sn,Zn and Pb.It can handle the calculation of phase diagrams in all combinations of these elements and all composition ranges.In addition,based on this tool,the liquidus,solidus,phase fractions and constitutions,equilibrium and non-equilibrium solidification behavior,surface tension and viscosity of liquid,diffusion reactions and microstructural evolution,etc.can be predicted.Typical examples of the calculation and application of this tool are presented.The design tool is expected to be a powerful tool for the development of Pb-free solders,as well as for promoting the understanding of the interfacial phenomena between Cu substrate and Pb-free solders in electronic packaging technology.

  1. Study of contact-reaction soldering of graphite to steel using the method of experiment planning

    International Nuclear Information System (INIS)

    The aim of the present investigation in the searching of the optimum condition of soldering of graphite (GM3, ARV, MPG6, VPP) to steel and to cast iron (St3, 45, U8 steel SCh12-28 cast+iron), providing the production of maximally strong and electric conducting weld as well as the study on the effect of graphite structure and of carbon content in soldering steel on exploitational properties of soldered samples. On the basis of studies carried out suppositions are made on the mechanism of fracture of soldered graphit-steel joints, as well as the prevailing role of soldering pressure and graphite structure on the strength of soldered joint is significant

  2. High-speed through-silicon via filling method using Cu-cored solder balls

    Institute of Scientific and Technical Information of China (English)

    He Ran; Wang Huijuan; Yu Daquan; Zhou Jing; Dai Fengwei; Song Chongshen; Sun Yu; Wan Lixi

    2012-01-01

    A novel low-cost and high-speed via filling method using Cu-cored solder balls was investigated for through-silicon via manufacture.Cu-cored solder balls with a total diameter of 100 μm were used to fill 150 μm deep,110 μm wide vias in silicon.The wafer-level filling process can be completed in a few seconds,which is much faster than using the traditional electroplating process.Thermo-mechanical analysis of via filling using solder,Cu and Cu-cored solder was carried out to assess the thermo-mechanical properties of the different filling materials.It was found that the vias filled with Cu-cored solder exhibit less thermal-mechanical stresses than solder-filled vias,but more than Cu-filled vias.

  3. Wettability and Reaction between Solder and Silver Busbar during the Tabbing Process for Silicon Photovoltaic Modules

    Science.gov (United States)

    Lee, Beom-Yong; Hoang, Thi-Lien; Cho, Sung-Bin; Huh, Joo-Youl; Lee, Young-Sik

    2012-10-01

    The soldering quality of a Cu ribbon onto the Ag busbars of solar cells is one of the key factors affecting the cell-to-module loss and durability of a silicon photovoltaic module. In this study, we examined the effects of the surface chemistry and morphology of the screen-printed Ag busbars on the solder wettability and bonding uniformity of the Cu ribbon over the length of the busbar during the tabbing process. The surface of the as-fired Ag busbar was covered by a thin glass layer originating from the glass frit contained in the Ag paste. The presence of the thin glass layer significantly decreased the wettability of the solder, leading to the formation of voided regions at the solder/busbar interface. Although it had only a minor influence on solder wettability, increasing the roughness of the busbar surface resulted in the formation of more voided regions at the solder/busbar interface.

  4. The Mechanical Behavior of Sn-Ag4 Solder Joints Subjected to Thermal Cycling

    Institute of Scientific and Technical Information of China (English)

    CHENGuohai; MAJusheng

    2004-01-01

    The method of mount strain gages is used to measure the stress/strain hysteresis loops of the solder joints under thermal cycling. The results show that different solders have different loops; the shape of the loops will change less, and finally become a line along with the thermal cycle increase. The shear module decreases along with the thermal cycling process. But the creep index of the solder joints is not sensitive to the cycling process,which fluctuates between 5 and 7. Because the elements of the solder and matrix materials diffuse during the process, the voids induced in the solder joints expand. The expansion of the voids will lead to the crystal lattice aberrance of solder crystal.

  5. Effects of particle size on the mechanical properties of particle-reinforced Sn-Ag composite solder joint

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    Particulate size has significant influenced on the mechanical properties of particle-reinforced composite solder joints. In this current research, Cu or Ni reinforcement particles were mechanically added to the Sn-3.5Ag eutectic solder, and the effects of the particle size on the mechanical properties of particle-reinforced composite solder joint were systematically studied. This investigation touched on how mechanical properties of the solder joints are affected by particles size. A quantitative formula was set up to correlate the mechanical property of the solder joint with particle size in different processing conditions. Besides, the fracture mechanism of the composite solder joint was analyzed.

  6. Effects of particle size on the mechanical properties of particle-reinforced Sn-Ag composite solder joint

    Institute of Scientific and Technical Information of China (English)

    TAI Feng; GUO Fu

    2009-01-01

    Particulate size has significant influenced on the mechanical properties of particle-reinforced compos-ite solder joints. In this current research, Cu or Ni reinforcement particles were mechanically added to the Sn-3.5Ag eutectic solder, and the effects of the particle size on the mechanical properties of parti-cle-reinforced composite solder joint were systematically studied. This investigation touched on how mechanical properties of the solder joints are affected by particles size. A quantitative formula was set up to correlate the mechanical property of the solder joint with particle size in different processing conditions. Besides, the fracture mechanism of the composite solder joint was analyzed.

  7. Microstructure, phases morphologies and hardness of a Bi–Ag eutectic alloy for high temperature soldering applications

    International Nuclear Information System (INIS)

    Highlights: • Growth of eutectic cells prevailed for lower “v” values. • The experimental growth formula λ2v = C encompasses eutectic growth. • Interphase spacing between Ag-rich spheroids occurred in the range 0.4–1.7 μm. • Hall–Petch type equations are proposed relating to hardness. - Abstract: The conversion to RoHS-compliant lead-free assembly has been a considerable challenge to the electronics industry. Among several alternative solder alloys, Bi–Ag alloys have been highlighted as a potential candidate to replace high Pb solder alloys for applications in oil and gas, automotive and avionics industries. The typical melting temperatures of Bi–Ag near-eutectic alloys are considered acceptable and excellent mechanical properties may be achieved with appropriate microstructures. Such promising alloys for high temperature soldering remain barely understood especially regarding non-equilibrium solidification features. In this study, a directional solidification experiment was carried out with the Bi–2.5 wt%Ag eutectic so that a large range of cooling rates (T) could be obtained under unsteady-state conditions. The experimental investigation include: thermal solidification parameters (growth rate, v and cooling rate, T), microstructure parameters (eutectic/dendritic spacing, interphase spacings) and phases morphologies analyzed by optical microscopy, scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), and hardness. Experimental interrelations between hardness and microstructure (scale and morphology) of the eutectic Bi–Ag are reported. Solidification parameters are also associated with each configuration observed along the casting, i.e., coexistence of dendrites and eutectic cells for regions very close to the cooled casting surface, eutectic cells prevailing and eutectic cells together with β-Bi primary phase. The cell spacing, λc, is correlated with hardness by Hall–Petch type equations

  8. Influence of Sb on IMC growth in Sn-Ag-Cu-Sb Pb-free solder joints in reflow process

    International Nuclear Information System (INIS)

    The influence of Sb on the soldering reaction and growth kinetics of Intermetallic compound (IMC) in Sn-3.5Ag-0.7Cu-xSb (x=0, 0.5, 1.0, and 1.5) lead-free solder joints is investigated in this study. Scanning electron microscope (SEM) is used to observe microstructure evolution of solder joint and to estimate the thickness and the grain size of the intermetallic layers. IMC phases are identified by energy dispersive X-ray (EDX) and X-ray diffractometer (XRD). Results show that some of the Sb powders are dissolved in the β-Sn matrix (Sn-rich phase), some of them participate in the form of Ag3(Sn, Sb), and the rest dissolves in the Cu6Sn5 IMC layer. Both thickness and grain size of IMC decrease when Sb is added. The growth exponents for both IMC layer and grains are determined by curve-fitting. The results reveal that Sn-3.5Ag-0.7Cu with about 1.0 wt.% Sb solder system exhibits the smallest growth rate and gives the most prominent effect in retarding IMC growth and refining IMC grain size. Based on the thermodynamic and phase diagram analysis, Sb has higher affinity to Sn element, and it will reduce the activity of Sn by forming SnSb compound, resulting in a decreased driving force for Cu-Sn IMC formation. A heterogeneous nucleation effect for retarding the IMC growth due to Sb addition is proposed

  9. Intermetallic growth at the interface between copper and bismuth-tin solder

    OpenAIRE

    Vollweiler, Fred O. P.

    1993-01-01

    Approved for public release; distribution is unlimited. Tin-bismuth alloys have been proposed as alternatives to lead containing solders for interconnection and packaging applications. Consequently, the interface between copper metallizations and bismuth-tin solders needs to be evaluated with respect to brittle intermetallic formation. In the binary Bi-Sn alloys both the Cu6Sn5 and Cu3Sn intermetallic phases were found at the Cu/ solder interface after exposure at 250 deg C, 300 deg C, and...

  10. Identification of putative candidate genes for red rot resistance in sugarcane (Saccharum species hybrid) using LD-based association mapping.

    Science.gov (United States)

    Singh, Ram K; Banerjee, Nandita; Khan, M S; Yadav, Sonia; Kumar, Sanjeev; Duttamajumder, S K; Lal, Ram Ji; Patel, Jinesh D; Guo, H; Zhang, Dong; Paterson, Andrew H

    2016-06-01

    Red rot is a serious disease of sugarcane caused by the fungus Colletotrichum falcatum that has a colossal damage potential. The fungus, prevalent mainly in the Indian sub-continent, keeps on producing new pathogenic strains leading to breakdown of resistance in newly released varieties and hence the deployment of linked markers for marker-assisted selection for resistance to this disease can fine tune the breeding programme. This study based on a panel of 119 sugarcane genotypes fingerprinted for 944 SSR alleles was undertaken with an aim to identify marker-trait associations (MTAs) for resistance to red rot. Mixed linear model containing population structure and kinship as co-factor detected four MTAs that were able to explain 10-16 % of the trait variation, individually. Among the four MTAs, EST sequences diagnostic of three could be BLAST searched to the sorghum genome with significant sequence homology. Several genes encoding important plant defence related proteins, viz., cytochrome P450, Glycerol-3-phosphate transporter-1, MAP Kinase-4, Serine/threonine-protein kinase, Ring finger domain protein and others were localized to the vicinity of these MTAs. These positional candidate genes are worth of further investigation and possibly these could contribute directly to red rot resistance, and may find a potential application in marker-assisted sugarcane breeding. PMID:26961118

  11. New π-Conjugated Materials Based on Furylenevinylene Candidate for Organic Solar Cells Application: A DFT Study

    Directory of Open Access Journals (Sweden)

    El Alamy Aziz

    2015-12-01

    Full Text Available The specific properties of organic-conjugated molecules and polymers are of great importance since they have become the most promising materials for the optoelectronic device technology such as solar cells. The use of low band gap materials is a viable method for better harvesting of the solar spectrum and increasing its efficiency. The control of the parameters of these materials is a research issue of ongoing interest. In this work, a quantum chemical investigation was performed to explore the optical and electronic properties of a series of different compounds based on furylenevinylene. Different electron side groups were introduced to investigate their effects on the electronic structure. The theoretical knowledge of the highest occupied molecular orbital (HOMO and lowest unoccupied molecular orbital (LUMO energy levels of the components is basic in studying organic solar cells; so the HOMO, LUMO, Gap energy and open circuit voltage (Voc of the studied compounds have been calculated and reported. These properties suggest that these materials behave as good candidate for organic solar cells. DOI: http://dx.doi.org/10.17807/orbital.v7i4.763 

  12. Glutathione transferase (GST) as a candidate molecular-based biomarker for soil toxin exposure in the earthworm Lumbricus rubellus

    International Nuclear Information System (INIS)

    The earthworm Lumbricus rubellus (Hoffmeister, 1843) is a terrestrial pollution sentinel. Enzyme activity and transcription of phase II detoxification superfamily glutathione transferases (GST) is known to respond in earthworms after soil toxin exposure, suggesting GST as a candidate molecular-based pollution biomarker. This study combined sub-proteomics, bioinformatics and biochemical assay to characterise the L. rubellus GST complement as pre-requisite to initialise assessment of the applicability of GST as a biomarker. L. rubellus possesses a range of GSTs related to known classes, with evidence of tissue-specific synthesis. Two affinity-purified GSTs dominating GST protein synthesis (Sigma and Pi class) were cloned, expressed and characterised for enzyme activity with various substrates. Electrospray ionisation mass spectrometry (ESI-MS) and tandem mass spectrometry (MS/MS) following SDS-PAGE were superior in retaining subunit stability relative to two-dimensional gel electrophoresis (2-DE). This study provides greater understanding of Phase II detoxification GST superfamily status of an important environmental pollution sentinel organism. - This study currently provides the most comprehensive view of the Phase II detoxification enzyme superfamily of glutathione transferases within the important environmental pollution sentinel earthworm Lumbricus rubellus.

  13. The (w)hole survey: an unbiased sample study of transition disk candidates based on Spitzer catalogs

    CERN Document Server

    van der Marel, Nienke; van Terwisga, Sierk; Merin, Bruno; Herczeg, Gregory; Ligterink, Niels F W; van Dishoeck, Ewine F

    2016-01-01

    Understanding disk evolution and dissipation is essential for studies of planet formation. Transition disks, i.e., disks with large dust cavities and gaps, are promising candidates of active evolution. About two dozen SED-selected candidates have been confirmed to have dust cavities through millimeter interferometric imaging, but this sample is biased towards the brightest disks. The Spitzer surveys of nearby low-mass star forming regions have resulted in more than 4000 Young Stellar Objects (YSOs). Using color criteria we have selected a sample of ~150 candidates, and an additional 40 candidates and known transition disks from the literature. The Spitzer data were complemented by new observations at longer wavelengths, including new JCMT and APEX submillimeter photometry, and WISE and Herschel-PACS mid and far-infrared photometry. Furthermore, optical spectroscopy was obtained and stellar types were derived for 85% of the sample, including information from the literature. The SEDs were fit to a grid of RADMC...

  14. Application of CO2 laser for electronic components soldering

    Science.gov (United States)

    Mascorro-Pantoja, J.; Soto-Bernal, J. J.; Nieto-Pérez, M.; Gonzalez-Mota, R.; Rosales-Candelas, I.

    2011-10-01

    Laser provides a high controllable and localized spot for soldering joint formation and this is a valuable tool in Sn/Pb Soldering process on electronic industry, in recent years, laser beam welding has become an emerging welding technique, the use of laser in welding area is a high efficiency method. A 60 Watts CO2 continuous laser was used on this study, during welding experimental results indicated the laser could significantly improve speed and weld quality. In this work, the welding interactions of CO2 laser with Sn/Pb wire have been investigated in details through varying the energy ratios of laser. And at the same time, the effect of distance from laser spot to material.

  15. Automated inspection of solder joints for surface mount technology

    Science.gov (United States)

    Savage, Robert M.; Park, Hyun Soo; Fan, Mark S.

    1993-03-01

    Researchers at NASA/GSFC evaluated various automated inspection systems (AIS) technologies using test boards with known defects in surface mount solder joints. These boards were complex and included almost every type of surface mount device typical of critical assemblies used for space flight applications: X-ray radiography; X-ray laminography; Ultrasonic Imaging; Optical Imaging; Laser Imaging; and Infrared Inspection. Vendors, representative of the different technologies, inspected the test boards with their particular machine. The results of the evaluation showed limitations of AIS. Furthermore, none of the AIS technologies evaluated proved to meet all of the inspection criteria for use in high-reliability applications. It was found that certain inspection systems could supplement but not replace manual inspection for low-volume, high-reliability, surface mount solder joints.

  16. Research Progress in Solderable Black Pad of Electroless Nickel/Immersion Gold

    Institute of Scientific and Technical Information of China (English)

    Liu Haiping; Li Ning; Bi Sifu; Li Deyu

    2007-01-01

    Electroless nickel/immersion gold (ENIG) technology is widely used as one of the surface final finish for electronics packaging substrate and printed circuit board (PCB), providing a protective, conductive and solderable surface. However, there is a solder joint interfacial brittle fracture (or solderability failure) of using the ENIG coating. The characteristics and the application of ENIG technology were narrated in this paper. The research progress on the solderability failure of ENIG was introduced. The mechanism of "black pad" and the possible measure of eliminating or alleviating the "black pad" were also introduced. The development direction and market prospects of ENIG were prospected.

  17. Role of Ag in the formation of interfacial intermetallic phases in Sn-Zn soldering

    Science.gov (United States)

    Song, Jenn-Ming; Liu, Pei-Chi; Shih, Chia-Ling; Lin, Kwang-Lung

    2005-09-01

    This study explored the effect of Ag as the substrate or alloying element of solders on the interfacial reaction in Sn-Zn soldering. Results show that instead of Ag-Sn compounds, ζ-AgZn and γ-Ag5Zn8 form at the Sn-Zn/Ag interface. The addition of Ag in Sn-Zn solders leads to the precipitation of ɛ-AgZn3 from the liquid solder on preformed interfacial intermetallics. The morphology of this additional AgZn3 is closely related to the solidification process of Ag-Zn intermetallics and the under intermetallic layer.

  18. Quality Analysis of Welded and Soldered Joints of Cu-Nb Microcomposite Wires

    Directory of Open Access Journals (Sweden)

    Nikolaj VIŠNIAKOV

    2011-03-01

    Full Text Available Quality analysis of welded and soldered joints of Cu-Nb microcomposite wires has been performed. Quality and mechanical characteristics of joints as ultimate tensile stress limit and elongation at break were measured with an universal testing machine and controlled visually using an optical microscope. Two wires joints were soldered with silver and copper solders and put into steel and copper sleeve respectively. Another two wires joints were soldered with silver solder and welded without any reinforcement. Joints soldered with the silver solder and steel sleeve have demonstrated the best mechanical characteristics: ultimate tensile stress limit of 650 MPa and elongation at break of 0.85 %. Joints soldered with the copper sleeve have no advantages comparing with the soldered butt joint. Ultimate tensile stress limit and elongation at break were in 300 MPa - 350 MPa and in 0.35 % - 0.45 % ranges respectively. Two welded joints had ultimate tensile stress limit of 470 MPa and elongation at break of 0.71 %. In all joints the microstructure of Nb filaments was destroyed and mechanical properties have been specified by mechanical strength of copper and sleeve materials only.http://dx.doi.org/10.5755/j01.ms.17.1.242

  19. Miniaturized frequency doubled DPSS laser soldered for space applications

    OpenAIRE

    Gilaberte Basset, Marta

    2014-01-01

    This master thesis presents the research performed to reach the optimum assembling technique for the miniaturized green laser for the ESA Exomars space mission. The strong requirements on optical performance of the laser, in combination with the space resistance needs, make a challenge to assemble this laser. The objective of this master thesis is to demonstrate that assembling the laser using the solderjet soldering technology studied and developed by Fraunhofer IOF is the solution for the l...

  20. A new strategy based on SmRho protein loaded chitosan nanoparticles as a candidate oral vaccine against schistosomiasis.

    Directory of Open Access Journals (Sweden)

    Carolina R Oliveira

    Full Text Available BACKGROUND: Schistosomiasis is one of the most important neglected tropical diseases and an effective control is unlikely in the absence of improved sanitation and vaccination. A new approach of oral vaccination with alginate coated chitosan nanoparticles appears interesting because their great stability and the ease of target accessibility, besides of chitosan and alginate immunostimulatory properties. Here we propose a candidate vaccine based on the combination of chitosan-based nanoparticles containing the antigen SmRho and coated with sodium alginate. METHODS AND FINDINGS: Our results showed an efficient performance of protein loading of nanoparticles before and after coating with alginate. Characterization of the resulting nanoparticles reported a size around 430 nm and a negative zeta potential. In vitro release studies of protein showed great stability of coated nanoparticles in simulated gastric fluid (SGF and simulated intestinal fluid (SIF. Further in vivo studies was performed with different formulations of chitosan nanoparticles and it showed that oral immunization was not able to induce high levels of antibodies, otherwise intramuscular immunization induced high levels of both subtypes IgG1 and IgG2a SmRho specific antibodies. Mice immunized with nanoparticles associated to CpG showed significant modulation of granuloma reaction. Mice from all groups immunized orally with nanoparticles presented significant levels of protection against infection challenge with S. mansoni worms, suggesting an important role of chitosan in inducing a protective immune response. Finally, mice immunized with nanoparticles associated with the antigen SmRho plus CpG had 38% of the granuloma area reduced and also presented 48% of protection against of S. mansoni infection. CONCLUSIONS: Taken together, this results support this new strategy as an efficient delivery system and a potential vaccine against schistosomiasis.

  1. Cartan's soldered spaces and conservation laws in physics

    Science.gov (United States)

    Kouneiher, Joseph; Barbachoux, Cécile

    2015-06-01

    In this paper, we will introduce a generalized soldering p-forms geometry, which can be the right framework to describe many new approaches and concepts in modern physics. Here we will treat some aspects of the theory of local cohomology in fields theory or more precisely the theory of soldering-form conservation laws in physics. We provide some illustrative applications, primarily taken from the Einstein equations of general theory of relativity and Yang-Mills theory. This theory can be considered to be a generalization of Noether's theory of conserved current to differential forms of any degree. An essential result of this, is that the conservation of the energy-momentum in general relativity, is linked to the fact that the vacuum field equations are equivalent to the integrability conditions of a first-order system of differential equations. We also apply the idea of the soldered space and the integrability conditions to the case of Yang-Mills theory. The mathematical framework, where these intuitive considerations would fit naturally, can be used to describe also the dynamics of changing manifolds.

  2. Blood-based gene expression signatures of medication-free outpatients with major depressive disorder: integrative genome-wide and candidate gene analyses

    OpenAIRE

    Hiroaki Hori; Daimei Sasayama; Toshiya Teraishi; Noriko Yamamoto; Seiji Nakamura; Miho Ota; Kotaro Hattori; Yoshiharu Kim; Teruhiko Higuchi; Hiroshi Kunugi

    2016-01-01

    Several microarray-based studies have investigated gene expression profiles in major depressive disorder (MDD), yet with highly variable findings. We examined blood-based genome-wide expression signatures of MDD, focusing on molecular pathways and networks underlying differentially expressed genes (DEGs) and behaviours of hypothesis-driven, evidence-based candidate genes for depression. Agilent human whole-genome arrays were used to measure gene expression in 14 medication-free outpatients wi...

  3. Comparison of Sn-Ag-Cu Solder Alloy Intermetallic Compound Growth Under Different Thermal Excursions for Fine-Pitch Flip-Chip Assemblies

    Science.gov (United States)

    Tian, Ye; Liu, Xi; Chow, Justin; Wu, Yi Ping; Sitaraman, Suresh K.

    2013-08-01

    The intermetallic compound (IMC) evolution in Cu pad/Sn-Ag-Cu solder interface and Sn-Ag-Cu solder/Ni pad interface was investigated using thermal shock experiments with 100- μm-pitch flip-chip assemblies. The experiments show that low standoff height of solder joints and high thermomechanical stress play a great role in the interfacial IMC microstructure evolution under thermal shock, and strong cross-reaction of pad metallurgies is evident in the intermetallic growth. Furthermore, by comparing the IMC growth during thermal aging and thermal shock, it was found that thermal shock accelerates IMC growth and that kinetic models based on thermal aging experiments underpredict IMC growth in thermal shock experiments. Therefore, new diffusion kinetic parameters were determined for the growth of (Cu,Ni)6Sn5 using thermal shock experiments, and the Cu diffusion coefficient through the IMC layer was calculated to be 0.2028 μm2/h under thermal shock. Finite-element models also show that the solder stresses are higher under thermal shock, which could explain why the IMC growth is faster and greater under thermal shock cycling as opposed to thermal aging.

  4. Tin Whisker Growth on the Surface of Sn-0.7Cu Lead-Free Solder with a Rare Earth (Nd) Addition

    Science.gov (United States)

    Liu, Meng; Xian, Ai-Ping

    2009-11-01

    The phenomenon of rare earth (RE) additions inducing whisker growth in Sn-0.7Cu-Nd (0.1-5 wt.%Nd) solder is reported. The results showed that Nd exists as Sn3Nd in the microstructure of the solder alloys. A snowflake-like Sn3Nd was observed when Nd ≤ 0.5 wt.%. After exposure to ambient conditions, the Nd-bearing alloys have a strong tendency toward whisker growth, with a short incubation time for whisker nucleation (only several hours). All whiskers originated from the Sn-Nd compound, where whiskers grew relatively fast; the average growth rate of the five longest whiskers was approximately 4 Å/s, and a 190 μm whisker was observed within 480 h. Based on these results, it was predicted that whisker growth would be inevitable for all RE-bearing solders. The cause of this phenomenon is also discussed. Finally, the authors suggest that any solders doped with RE should be carefully considered again.

  5. Novel Plasmodium falciparum malaria vaccines: evidence-based searching for variant surface antigens as candidates for vaccination against pregnancy-associated malaria

    DEFF Research Database (Denmark)

    Staalsoe, Trine; Jensen, Anja T R; Theander, Thor G; Hviid, Lars

    2002-01-01

    statistically significant co-variation with protection rather than on demonstration of causal relationships. We have studied the relationship between variant surface antigen-specific antibodies and clinical protection from Plasmodium falciparum malaria in general, and from pregnancy-associated malaria (PAM) in......Malaria vaccine development has traditionally concentrated on careful molecular, biochemical, and immunological characterisation of candidate antigens. In contrast, evidence of the importance of identified antigens in immunity to human infection and disease has generally been limited to...... particular, to provide robust evidence of a causal link between the two in order to allow efficient and evidence-based identification of candidate antigens for malaria vaccine development....

  6. Field based measurements of albedo for two candidate perennial cellulosic feedstocks and row crops in Central Illinois

    Science.gov (United States)

    Miller, J. N.; VanLoocke, A.; Bernacchi, C. J.

    2012-12-01

    The production of perennial cellulosic feedstocks for bioenergy present the potential to diversify regional economies and the national energy supply, while also serving as a climate 'regulators' due to a number of biogeochemical and biophysical differences relative to row crops. Numerous observationally and modeling based approaches, including life cycle analyses have investigated biogeochemical tradeoffs, such as increased carbon sequestration and biophysical increased water use, associated with growing cellulosic feedstocks. A less understood aspect is the biophysical changes associated with the difference in albedo, which will alter the local energy balance and could cause a local to regional cooling several times larger than that associated with offsetting carbon. To address this factor an experiment consisting of paired fields of Miscanthus and Switchgrass, two of the leading perennial cellulosic feedstock candidates, and traditional row crops was established in central Illinois. Data from the first two growing seasons indicate that this effect is most pronounced during the spring and fall as perennial biofuel crops green up earlier and senesce later than common annual row crops. The albedo of the perennials converges to that of the row crops during the growing season as the canopies develop. During the early winter, before the perennial crops are harvested, the albedo over fallow soybean and maize fields can vary greatly depending on snowfall and, to a lesser extent, soil moisture, whereas perennials show less variation. Thus, perennial biofuel crops also have the potential to buffer the local environment against short-term variations in climate. These factors should be considered when evaluating the tradeoffs and climate-regulation services associated with large-scale planting of bioenergy crops.

  7. Effect of iron and indium on IMC formation and mechanical properties of lead-free solder

    International Nuclear Information System (INIS)

    Highlights: ► The addition of In and Ce/Fe affected the IMC morphology and increased shear strength. ► The addition of Fe resulted in increased wettability of the SAC solder. ► The melting Point of the SAC solder was decreased by the addition of In and Ce. ► The addition of Fe/In and Ce led to a decrease in the CTE. ► The addition of 0.6Fe/In and Ce resulted in a single peak in DSC, despite the addition of 0.2Fe. - Abstract: In recent years, because of environmental concerns, lead solders have been replaced by lead-free solders. One of the numerous lead-free solders developed in the past several years is the Sn–Ag–Cu (SAC) eutectic solder. This work explored the effects of adding iron and indium to the reliability of SAC solder. Four different solders have been fabricated by adding Fe or In into the solder, i.e., Sn3.6Ag0.9Cu (SAC–E), SAC–Fe02, SAC–Fe06 and SAC–InCe. DSC results showed that adding indium decreased the melting point of SAC, and the single eutectic peak was maintained in all cases. Solders were reflowed on bare Cu and electroless Ni–P-coated substrates. It was found that the SAC–E and SAC–InCe gave the highest and the lowest IMC thickness, respectively among all solders. The same pattern was observed in the wetting angle measurement. Shear strength results showed that the SAC–Fe06 and SAC–Fe02 solder displayed the highest strength, followed by SAC–InCe and the SAC–E solder had the lowest strength. Results suggest that adding small amounts of Fe and In and Ce improved the wettability and shear strength of the SAC solder. Also, the Coefficient of thermal expansion measurement showed a possible decrease in thermal expansion mismatch with the addition of In and Ce and Fe into the SAC eutectic solder.

  8. A microstructural analysis of solder joints from the electronic assemblies of dismantled nuclear weapons

    Energy Technology Data Exchange (ETDEWEB)

    Vianco, P.T.; Rejent, J.A. [Sandia National Labs., Albuquerque, NM (United States). Materials Joining Dept.

    1997-05-01

    MC1814 Interconnection Boxes from dismantled B57 bombs, and MC2839 firing Sets from retired W70-1 warheads were obtained from the Pantex facility. Printed circuit boards were selected from these components for microstructural analysis of their solder joints. The analysis included a qualitative examination of the solder joints and quantitative assessments of (1) the thickness of the intermetallic compound layer that formed between the solder and circuit board Cu features, and (2) the Pb-rich phase particle distribution within the solder joint microstructure. The MC2839 solder joints had very good workmanship qualities. The intermetallic compound layer stoichiometry was determined to be that of Cu6Sn5. The mean intermetallic compound layer thickness for all solder joints was 0.885 mm. The magnitude of these values did not indicate significant growth over the weapon lifetime. The size distribution of the Pb-rich phase particles for each of the joints were represented by the mean of 9.85 {times} 10{sup {minus}6} mm{sup 2}. Assuming a spherical geometry, the mean particle diameter would be 3.54 mm. The joint-to-joint difference of intermetallic compound layer thickness and Pb-rich particle size distribution was not caused by varying thermal environments, but rather, was a result of natural variations in the joint microstructure that probably existed at the time of manufacture. The microstructural evaluation of the through-hole solder joints form the MC2839 and MC1814 components indicated that the environmental conditions to which these electronic units were exposed in the stockpile, were benign regarding solder joint aging. There was an absence of thermal fatigue damage in MC2839 circuit board, through-hole solder joints. The damage to the eyelet solder joints of the MC1814 more likely represented infant mortality failures at or very near the time of manufacture, resulting from a marginal design status of this type of solder joint design.

  9. Rock mass quality and support recommendations for basalt at the candidate repository horizon, based on the Q-system

    International Nuclear Information System (INIS)

    An analysis of the Q-system of rockmass characterization and tunnel support selection and its application to the candidate repository horizon is provided. The range of rockmass qualities, tunnel sizes and tunnel depths which constitute the Q-system database are reviewed and related to the quality of the candidate repository horizon, rock conditions equivalent to those in the candidate horizon are thoroughly documented. A detailed review of pertinent BWIP documents was undertaken to estimate general conditions and possible extreme conditions, and resulted in determining an extreme range of Q from 0.05 to 10 and a design range of 0.4 to 4. Detailed rock reinforcement recommendations, incorporating appropriate reinforcement for typical and extreme colonnade and entablature, were derived for roofs, walls and intersections in all planned tunnels. 35 refs., 31 figs., 19 tabs

  10. A biologically-inspired framework for contour detection using superpixel-based candidates and hierarchical visual cues.

    Science.gov (United States)

    Sun, Xiao; Shang, Ke; Ming, Delie; Tian, Jinwen; Ma, Jiayi

    2015-01-01

    Contour detection has been extensively investigated as a fundamental problem in computer vision. In this study, a biologically-inspired candidate weighting framework is proposed for the challenging task of detecting meaningful contours. In contrast to previous models that detect contours from pixels, a modified superpixel generation processing is proposed to generate a contour candidate set and then weigh the candidates by extracting hierarchical visual cues. We extract the low-level visual local cues to weigh the contour intrinsic property and mid-level visual cues on the basis of Gestalt principles for weighting the contour grouping constraint. Experimental results tested on the BSDS benchmark show that the proposed framework exhibits promising performances to capture meaningful contours in complex scenes. PMID:26492252

  11. Research on Void Rate of Eutectic Solder Welding%共晶焊料焊接的孔隙率研究

    Institute of Scientific and Technical Information of China (English)

    陈波; 丁荣峥; 明雪飞; 高娜燕

    2012-01-01

      大功率或高功率密度的高可靠集成电路等通常采用合金焊料焊接芯片,以降低封装热阻和提高芯片焊接的可靠性。合金焊料焊接方式主要有真空烧结、保护气氛下静压烧结、共晶摩擦焊等。不同焊接工艺有其不同的适应性和焊接可靠性。文章以高可靠封装常用金基焊料的共晶焊接为例,探讨在相同封装结构、不同共晶焊接工艺下焊接层孔隙率,以及相同工艺设备、工艺条件下随芯片尺寸增大孔隙率的变化趋势。研究结果表明:金-硅共晶摩擦焊工艺的孔隙率低于金-锡真空烧结工艺和金-锡保护气氛静压烧结;同一焊接工艺,随着芯片尺寸变大,其孔隙率变化不显著,但单个空洞的尺寸有明显增大趋势。%  Alloy solder slice is widely used in the package of IC devices with high power or high power density. Generally, these IC devices are called for high reliability which is realized by the use of alloy solder slice, while it decreases the heat resistance of IC package. The widely used processes for alloy soldering are soldering in vacuum, soldering in protecting gas same as atmospheric pressure, jointing with eutectic scrub, etc. These processes vary in soldering reliability and are employed in different conditions according to different demands. It is reported that how the eutectic soldering process and chip size influence the void rate of Au-based alloy. Researches show that, void rate of Au-Si eutectic scrub bonding is lower than Au-Sn alloy jointing in vacuum and Au-Sn alloy jointing in protecting gas;void rate does not but the size of single void does obviously change as chip size increases.

  12. Quantitative iTRAQ-Based Proteomic Identification of Candidate Biomarkers for Diabetic Nephropathy in Plasma of Type 1 Diabetic Patients

    DEFF Research Database (Denmark)

    Overgaard, Anne Julie; Thingholm, Tine Engberg; Larsen, Martin R;

    2010-01-01

    INTRODUCTION: As part of a clinical proteomics programme focused on diabetes and its complications, it was our goal to investigate the proteome of plasma in order to find improved candidate biomarkers to predict diabetic nephropathy. METHODS: Proteins derived from plasma from a cross-sectional co...

  13. Isoquinoline-based analogs of the cancer drug clinical candidate tipifarnib as anti-Trypanosoma cruzi agents

    OpenAIRE

    Chennamaneni, Naveen Kumar; Arif, Jenifer; Buckner, Frederick S.; Gelb, Michael H

    2009-01-01

    We developed a synthetic route to prepare isoquinoline analogs of the cancer drug clinical candidate tipifarnib. We show that these compounds kill Trypanosoma cruzi amastigotes grown in mammalian host cells at concentrations in the low nanomolar range. These isoquinolines represent new leads for the development of drugs to treat Chagas disease.

  14. Development of technique for laser welding of biological tissues using laser welding device and nanocomposite solder.

    Science.gov (United States)

    Gerasimenko, A; Ichcitidze, L; Podgaetsky, V; Ryabkin, D; Pyankov, E; Saveliev, M; Selishchev, S

    2015-08-01

    The laser device for welding of biological tissues has been developed involving quality control and temperature stabilization of weld seam. Laser nanocomposite solder applied onto a wound to be weld has been used. Physicochemical properties of the nanocomposite solder have been elucidated. The nature of the tissue-organizing nanoscaffold has been analyzed at the site of biotissue welding. PMID:26738200

  15. New multicomponent solder alloys of low melting pointfor low-cost commercial electronic assembly

    Science.gov (United States)

    Al-Ganainy, G. S.; Sakr, M. S.

    2003-09-01

    The requirements of the telecommunications, automobile, electronics and aircraft industries for non-toxic solders with melting points close to that of near-eutectic Pb-Sn alloys has led to the development of new Sn-Zn-In solder alloys. Differential thermal analysis (DTA) shows melting points of 198, 195, 190 and 185 +/- 2 °C for the alloys Sn-9Zn, Sn-9Zn-2In, Sn-9Zn-4In and Sn-9Zn-6In, respectively. An equation that fits the data relating the melting point to the In content in the solders is derived. The X-ray diffraction patterns are analyzed to determine the phases that exist in each solder. The stress-strain curves are studied in the temperature range from 90 to 130 °C for all the solders except for those that contain 4 wt% of In, where the temperature range continues to 150 °C. The work-hardening parameters, y (the yield stress), f (the fracture stress), and the parabolic work-hardening coefficient X, increase with increasing indium content in the solders at all working temperatures. They decrease with increasing working temperature for each solder, and show two relaxation stages only for the Sn-9Zn-4In solder around a temperature of 120 °C. (

  16. Brno Contribution to the COCT 531 Lead-Free Solders Thermodynamic Database

    Czech Academy of Sciences Publication Activity Database

    Kroupa, Aleš; Vřešťál, J.; Vízdal, J.; Zemanová, Adéla

    Vienna : Vienna University, 2007. s. 29-29. [COST Action 531 "Lead-Free Solder Materials". 17.05.2007-18.05.2007, Vienna] Institutional research plan: CEZ:AV0Z20410507 Keywords : lead-free solders Subject RIV: BJ - Thermodynamics

  17. Current Problems and Possible Solutions in High-Temperature Lead-Free Soldering

    Czech Academy of Sciences Publication Activity Database

    Kroupa, Aleš; Andersson, D.; Hoo, N.; Pearce, J.; Watson, A.; Dinsdale, A.; Mucklejohn, S.

    2012-01-01

    Roč. 21, č. 5 (2012), s. 629-637. ISSN 1059-9495 Institutional support: RVO:68081723 Keywords : lead-free soldering, * materials for high-temperature LF * new technologies for HT lead-free soldering Subject RIV: BJ - Thermodynamics Impact factor: 0.915, year: 2012

  18. 30 CFR 77.1111 - Welding, cutting, soldering; use of fire extinguisher.

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Welding, cutting, soldering; use of fire... OF UNDERGROUND COAL MINES Fire Protection § 77.1111 Welding, cutting, soldering; use of fire extinguisher. One portable fire extinguisher shall be provided at each location where welding, cutting,...

  19. Long-term creep rupture strength of weldment of Fe-Ni based alloy as candidate tube and pipe for advanced USC boilers

    Energy Technology Data Exchange (ETDEWEB)

    Bao, Gang; Sato, Takashi [Babcok-Hitachi K.K., Hiroshima (Japan). Kure Research Laboratory; Marumoto, Yoshihide [Babcok-Hitachi K.K., Hiroshima (Japan). Kure Div.

    2010-07-01

    A lot of works have been going to develop 700C USC power plant in Europe and Japan. High strength Ni based alloys such as Alloy 617, Alloy 740 and Alloy 263 were the candidates for boiler tube and pipe in Europe, and Fe-Ni based alloy HR6W (45Ni-24Fe-23Cr-7W-Ti) is also a candidate for tube and pipe in Japan. One of the Key issues to achieve 700 C boilers is the welding process of these alloys. Authors investigated the weldability and the long-term creep rupture strength of HR6W tube. The weldments were investigated metallurgically to find proper welding procedure and creep rupture tests are ongoing exceed 38,000 hours. The long-term creep rupture strengths of the HST weld joints are similar to those of parent metals and integrity of the weldments was confirmed based on with other mechanical testing results. (orig.)

  20. Intermetallics Characterization of Lead-Free Solder Joints under Isothermal Aging

    Science.gov (United States)

    Choubey, Anupam; Yu, Hao; Osterman, Michael; Pecht, Michael; Yun, Fu; Yonghong, Li; Ming, Xu

    2008-08-01

    Solder interconnect reliability is influenced by environmentally imposed loads, solder material properties, and the intermetallics formed within the solder and the metal surfaces to which the solder is bonded. Several lead-free metallurgies are being used for component terminal plating, board pad plating, and solder materials. These metallurgies react together and form intermetallic compounds (IMCs) that affect the metallurgical bond strength and the reliability of solder joint connections. This study evaluates the composition and extent of intermetallic growth in solder joints of ball grid array components for several printed circuit board pad finishes and solder materials. Intermetallic growth during solid state aging at 100°C and 125°C up to 1000 h for two solder alloys, Sn-3.5Ag and Sn-3.0Ag-0.5Cu, was investigated. For Sn-3.5Ag solder, the electroless nickel immersion gold (ENIG) pad finish was found to result in the lowest IMC thickness compared to immersion tin (ImSn), immersion silver (ImAg), and organic solderability preservative (OSP). Due to the brittle nature of the IMC, a lower IMC thickness is generally preferred for optimal solder joint reliability. A lower IMC thickness may make ENIG a desirable finish for long-life applications. Activation energies of IMC growth in solid-state aging were found to be 0.54 ± 0.1 eV for ENIG, 0.91 ± 0.12 eV for ImSn, and 1.03 ± 0.1 eV for ImAg. Cu3Sn and Cu6Sn5 IMCs were found between the solder and the copper pad on boards with the ImSn and ImAg pad finishes. Ternary (Cu,Ni)6Sn5 intermetallics were found for the ENIG pad finish on the board side. On the component side, a ternary IMC layer composed of Ni-Cu-Sn was found. Along with intermetallics, microvoids were observed at the interface between the copper pad and solder, which presents some concern if devices are subject to shock and vibration loading.

  1. Modeling of high temperature- and diffusion-controlled die soldering in aluminum high pressure die casting

    DEFF Research Database (Denmark)

    Domkin, Konstantin; Hattel, Jesper Henri; Thorborg, Jesper

    2009-01-01

    layers. The die-soldering model combines two approaches available in literature, describing the two aspects of die soldering: the growth of the intermetallic layer, and the thermal and metallurgical conditions in the layer that lead to the die soldering. The theoretical model is then extended with the...... treatment of the intermetallic layer growth controlled by the idealized effective diffusivity and with the treatment of solder strength dependent on the temperature and liquid fraction within the layer. The solder strength locally on the die surface is calculated as a function of the number of die...... agreement with the reports in literature. The influence of several casting process parameters such as cooling/spraying efficiency and other parameters that control the thermal history of the die and the casting is in agreement with the expected behavior....

  2. Modification of Sn-1.0Ag-0.5Cu solder using nickel and boron

    Institute of Scientific and Technical Information of China (English)

    Jun-Feng Qu; Jun Xu; Qiang Hu; Fu-Wen Zhang; Shao-Ming Zhang

    2015-01-01

    Effects of Ni and B additions on the microstructure and growth behavior of the intermetallic compound (IMC) of Sn-1.0Ag-0.5Cu alloys (SAC105) were investigated in this study.Results show that microadditions of Ni and B result in volume fraction of primary Sn increasing and the grain size decreasing observably.It is found that a large number of fine reinforcement particles with network-like shape are found in the solder,and the thickness of interfacial IMC layer in the solder joint is grew less than that of SAC 105 with longer aging time.Shear test results reveal that as-soldered solder joints of microalloyed SAC105 have better shear strength than that of SAC 105 solder alloy.

  3. Study on Mitigation Method of Solder Corrosion for Crystalline Silicon Photovoltaic Modules

    Directory of Open Access Journals (Sweden)

    Ju-Hee Kim

    2014-01-01

    Full Text Available The corrosion of 62Sn36Pb2Ag solder connections poses serious difficulties for outdoor-exposed photovoltaic (PV modules, as connection degradation contributes to the increase in series resistance (RS of PV modules. In this study, we investigated a corrosion mitigation method based on the corrosion mechanism. The effect of added sacrificial metal on the reliability of PV modules was evaluated using the oxidation-reduction (redox reaction under damp heat (DH conditions. Experimental results after exposure to DH show that the main reason for the decrease in power was a drop in the module’s fill factor. This drop was attributed to the increase of RS. The drop in output power of the PV module without added sacrificial metal is greater than that of the sample with sacrificial metal. Electroluminescence and current-voltage mapping analysis also show that the PV module with sacrificial metal experienced less degradation than the sample without sacrificial metal.

  4. Pb-free Sn-Ag-Cu ternary eutectic solder

    Science.gov (United States)

    Anderson, Iver E.; Yost, Frederick G.; Smith, John F.; Miller, Chad M.; Terpstra, Robert L.

    1996-06-18

    A Pb-free solder includes a ternary eutectic composition consisting essentially of about 93.6 weight % Sn-about 4.7 weight % Ag-about 1.7 weight % Cu having a eutectic melting temperature of about 217.degree. C. and variants of the ternary composition wherein the relative concentrations of Sn, Ag, and Cu deviate from the ternary eutectic composition to provide a controlled melting temperature range (liquid-solid "mushy" zone) relative to the eutectic melting temperature (e.g. up to 15.degree. C. above the eutectic melting temperature).

  5. Microstructure of model system for Pb-free nanoparticle solders

    Czech Academy of Sciences Publication Activity Database

    Buršík, Jiří; Sopoušek, J.; Zálešák, J.

    Luxembourg: Office for Official Publications of the European Communities, 2009 - (Fantechi, S.; Havlíčková, L.; Svobodová, E.; Fryček, R.; Albrecht, V.). s. 167-167 ISBN 978-92-79-11109-9. [European and International Forum on Nanotechnology: EuroNanoForum 2009 - Nanotechnology for Sustainable Economy . 02.06.2009-05.06.2009, Praha] R&D Projects: GA ČR(CZ) GA106/09/0700 Institutional research plan: CEZ:AV0Z20410507 Keywords : Pb-free nanoparticle solders * microstructure * X-ray analysis Subject RIV: BJ - Thermodynamics

  6. Reflow Soldering of Surface Mount Electronic Components in a Laboratory

    CERN Document Server

    Erickson, Christopher J

    2009-01-01

    We present a basic tutorial for implementing surface mount technology in lab-built scientific instruments. We discuss the advantages and disadvantages of using surface mount chips. We also describe methods for the development and prototyping of surface mount circuitry in home-built electronics. The method of soldering surface mount components in a common toaster oven is described. We provide advice from our own experience in developing this technology, and argue that surface mount technology is often preferable to using leaded components when building large circuits, and is essential if the desired component characteristics are only available in surface mount packages.

  7. Prioritizing Disease Candidate Proteins in Cardiomyopathy-Specific Protein-Protein Interaction Networks Based on “Guilt by Association” Analysis

    OpenAIRE

    Li, Wan; Chen, Lina; He, Weiming; Li, Weiguo; Qu, Xiaoli; Liang, Binhua; Gao, Qianping; Feng, Chenchen; Jia, Xu; Lv, Yana; Zhang, Siya; Li, Xia

    2013-01-01

    The cardiomyopathies are a group of heart muscle diseases which can be inherited (familial). Identifying potential disease-related proteins is important to understand mechanisms of cardiomyopathies. Experimental identification of cardiomyophthies is costly and labour-intensive. In contrast, bioinformatics approach has a competitive advantage over experimental method. Based on “guilt by association” analysis, we prioritized candidate proteins involving in human cardiomyopathies. We first built...

  8. Impact of Cooling Rate-Induced Recrystallization on High G Mechanical Shock and Thermal Cycling in Sn-Ag-Cu Solder Interconnects

    Science.gov (United States)

    Lee, Tae-Kyu; Bieler, Thomas R.; Kim, Choong-Un

    2016-01-01

    The mechanical stability and thermo-mechanical fatigue performance of solder joints with low silver content Sn-1.0Ag-0.5Cu (wt.%) (SAC105) alloy based on different cooling rates are investigated in high G level shock environment and thermal cycling conditions. The cooling rate-controlled samples ranging from 1°C/min to 75°C/min cooling rate, not only show differences in microstructure, where a fine poly-granular microstructure develops in the case of fast cooling versus normal cooling, but also show various shock performances based on the microstructure changes. The fast cooling rate improves the high G shock performance by over 90% compared to the normal cooled SAC105 alloy air-cooling environment commonly used after assembly reflow. The microstructure effect on thermal cycling performance is also discussed, which is analyzed based on the Sn grain orientation, interconnect stability, and solder joint bulk microstructure.

  9. Imaging and Analysis of Void-defects in Solder Joints Formed in Reduced Gravity using High-Resolution Computed Tomography

    Science.gov (United States)

    Easton, John W.; Struk, Peter M.; Rotella, Anthony

    2008-01-01

    As a part of efforts to develop an electronics repair capability for long duration space missions, techniques and materials for soldering components on a circuit board in reduced gravity must be developed. This paper presents results from testing solder joint formation in low gravity on a NASA Reduced Gravity Research Aircraft. The results presented include joints formed using eutectic tin-lead solder and one of the following fluxes: (1) a no-clean flux core, (2) a rosin flux core, and (3) a solid solder wire with external liquid no-clean flux. The solder joints are analyzed with a computed tomography (CT) technique which imaged the interior of the entire solder joint. This replaced an earlier technique that required the solder joint to be destructively ground down revealing a single plane which was subsequently analyzed. The CT analysis technique is described and results presented with implications for future testing as well as implications for the overall electronics repair effort discussed.

  10. Comprehensive analytical strategy for biomarker identification based on liquid chromatography coupled to mass spectrometry and new candidate confirmation tools.

    Science.gov (United States)

    Mohamed, Rayane; Varesio, Emmanuel; Ivosev, Gordana; Burton, Lyle; Bonner, Ron; Hopfgartner, Gérard

    2009-09-15

    A comprehensive analytical LC-MS(/MS) platform for low weight biomarkers molecule in biological fluids is described. Two complementary retention mechanisms were used in HPLC by optimizing the chromatographic conditions for a reversed-phase column and a hydrophilic interaction chromatography column. LC separation was coupled to mass spectrometry by using an electrospray ionization operating in positive polarity mode. This strategy enables us to correctly retain and separate hydrophobic as well as polar analytes. For that purpose artificial model study samples were generated with a mixture of 38 well characterized compounds likely to be present in biofluids. The set of compounds was used as a standard aqueous mixture or was spiked into urine at different concentration levels to investigate the capability of the LC-MS(/MS) platform to detect variations across biological samples. Unsupervised data analysis by principal component analysis was performed and followed by principal component variable grouping to find correlated variables. This tool allows us to distinguish three main groups whose variables belong to (a) background ions (found in all type of samples), (b) ions distinguishing urine samples from aqueous standard and blank samples, (c) ions related to the spiked compounds. Interpretation of these groups allows us to identify and eliminate isotopes, adducts, fragments, etc. and to generate a reduced list of m/z candidates. This list is then submitted to the prototype MZSearcher software tool which simultaneously searches several lists of potential metabolites extracted from metabolomics databases (e.g., KEGG, HMDB, etc) to propose biomarker candidates. Structural confirmation of these candidates was done off-line by fraction collection followed by nanoelectrospray infusion to provide high quality MS/MS data for spectral database queries. PMID:19702294

  11. Microstructure Evolution and Shear Behavior of the Solder Joints for Flip-Chip LED on ENIG Substrate

    Science.gov (United States)

    Liu, Yang; Sun, Fenglian; Luo, Liangliang; Yuan, Cadmus A.; Zhang, Guoqi

    2015-07-01

    The microstructure evolution and shear behavior of the solder joints for the flip-chip light-emitting diode on the electroless nickel/immersion gold (ENIG) substrate were investigated in this study. The experimental results reveal that the solder joints for the anode and cathode have different microstructures and failure characteristics during the shear test before and after isothermal aging. For the solder joints for the anode, the interfacial intermetallic compound (IMC) is (Au, Ni)Sn4 at the solder/anode interface but dendritic Ni3Sn4 grains at the solder/ENIG interface after reflow. Meanwhile, the dendritic Ni3Sn4 grains are surrounded by (Au, Ni)Sn4, which suppresses the growth of the Ni3Sn4 grains during aging. For the solder joints for the cathode, a nano scaled Au-rich layer can be observed near the cathode/solder layer interface after reflow. And the Au-rich layer moves toward the bulk solder because of the volume expansion by the transformation from Au into (Au, Ni)Sn4 during reflow and isothermal aging. Due to the diffusion of the Au atom from the Au-rich layer into the bulk solder, the Au-rich layer transformed into an interface inside of the solder joint. The average shear force of the solder joints shows a decrease from 380 gf to 250 gf because of the microstructure evolution during the isothermal aging for 1000 h at 85°C. After long time aging, the primary failure mode of the solder joint for the anode changed from the anode broken to the brittle failure of the solder layer. The delamination between the IMC layer and the insulation layer is suggested to be the dominated failure mode of the solder joint for the cathode after aging.

  12. Rapid communication: Computational simulation and analysis of a candidate for the design of a novel silk-based biopolymer.

    Science.gov (United States)

    Golas, Ewa I; Czaplewski, Cezary

    2014-09-01

    This work theoretically investigates the mechanical properties of a novel silk-derived biopolymer as polymerized in silico from sericin and elastin-like monomers. Molecular Dynamics simulations and Steered Molecular Dynamics were the principal computational methods used, the latter of which applies an external force onto the system and thereby enables an observation of its response to stress. The models explored herein are single-molecule approximations, and primarily serve as tools in a rational design process for the preliminary assessment of properties in a new material candidate. PMID:24723330

  13. Practical application of lead free solder in electronic production

    Energy Technology Data Exchange (ETDEWEB)

    Chae, K.S.; Min, J.S.; Kim, I.J.; Cho, I.J. [LG Electronics, Pyungtaek (Korea)

    2004-07-01

    At present, LG Electronics pushes ahead to eliminate the Pb(Lead) -a hazardous material- from all products. Especially, we have performed to select the optimum standard composition of lead free alloy for the application to products for about 3 years from 2000. These days, we have the chance for applying to the mass-production. This project constructed the system for applying the lead free solders on consumer electronic products, which is one of the major products of the LG Electronics. To select the lead free solders with corresponding to the product features, we have passed through the test and applied with Sn-3.0Ag-0.5Cu alloy system to our products, and for the application to the high melting temperature composition, we secured the thermal resistance of the many parts and substrate and optimized the processing conditions. We have operated the temperature cycling test and the high temperature storage test under the standards to confirm the reliability of the products. On these samples, we considered the consequence of our decision by the operating test. For the long life time of the product, we have operated the temperature cycling test at -45 C - + 125 C, 1 cycle/hour, 1000 cycles. Also we have tested the tin whisker growth about lead free plating on lead finish. We have analyzed with the SEM, EDS and any other equipment for confirming the failure mode at the joint and the tin whisker growth on lead free finish. (orig.)

  14. Effects of Temperature on the Wave Soldering of Printed Circuit Boards: CFD Modeling Approach

    Directory of Open Access Journals (Sweden)

    M.S. Abdul Aziz

    2016-01-01

    Full Text Available ABSTRACT This study investigated the effects of temperature on the wave soldering of printed circuit boards (PCBs using three-dimensional finite volume analysis. A computational solder pot model consisting of a six-blade rotational propeller was developed and meshed using tetrahedral elements. The leaded molten solder (Sn63Pb37 distribution and PCB wetting profile were determined using the volume of fluid technique in the fluid flow solver, FLUENT. In this study, the effects of five different molten solder temperatures (456 K, 473 K, 523 K, 583 K, and 643 K on the wave soldering of a 70 mm × 146 mm PCB were considered. The effects of temperature on wetting area, wetting profile, velocity vector, and full wetting time were likewise investigated. Molten solder temperature significantly affected the wetting time and distribution of PCBs. The molten solder temperature at 523 K demonstrated desirable wetting distribution and yielded a stable fountain profile and was therefore considered the best temperature in this study. The simulation results were substantiated by the experimental results.

  15. Effect of Au on the reliability of fine pitch surface mount solder joints

    Energy Technology Data Exchange (ETDEWEB)

    Glazer, J. (Hewlett-Packard Co., Palo Alto, CA (United States)); Kramer, P.; Morris, J.W. Jr. (Lawrence Berkeley Lab., CA (United States))

    1991-05-01

    The effect of Au on the reliability of 0.65 mm pitch surface mount solder joints between plastic quad flat packs and Cu-Ni-Au FR-4 printed circuit boards was investigated. Cu-Ni-Au is a desirable printed circuit board finish for multi-chip modules or printed circuit boards that would otherwise require a selective Au finish, for example for edge connectors or wire bondable parts. However, Au is known to embrittle solder when it is present in sufficiently high concentrations, creating a concern that solder joint fatigue life in service will also be adversely affected. This paper reports the results of mechanical shock, mechanical vibration and thermal cycling testing of fine pitch solder joints containing varying amounts of Au. Tests were performed on as-soldered joints and on joints that had been heat-treated to evolve the microstructure toward equilibrium. The tests were designed to accelerate in-service conditions in a typical industrial environment. Under these conditions, the Au concentrations tested did not promote solder joint failures. Microstructural characterization of the distribution and morphology of the Au-, Ni-, and Cu-Sn intermetallics in the joint before and after accelerated testing was also performed. On the basis of these observations it is recommended that the Au concentration in solder joints between plastic quad flat packs and Cu-Ni-Au FR-4 printed circuit boards not exceed 3.0 wt %. 13 refs., 6 figs.

  16. Simulation of Grain Growth in a Near-Eutectic Solder Alloy

    Energy Technology Data Exchange (ETDEWEB)

    TIKARE,VEENA; VIANCO,PAUL T.

    1999-12-16

    Microstructural evolution due to aging of solder alloys determines their long-term reliability as electrical, mechanical and thermal interconnects in electronics packages. The ability to accurately determine the reliability of existing electronic components as well as to predict the performance of proposed designs depends upon the development of reliable material models. A kinetic Monte Carlo simulation was used to simulate microstructural evolution in solder-class materials. The grain growth model simulated many of the microstructural features observed experimentally in 63Sn-37Pb, a popular near-eutectic solder alloy. The model was validated by comparing simulation results to new experimental data on coarsening of Sn-Pb solder. The computational and experimental grain growth exponent for two-phase solder was found to be much lower than that for normal, single phase grain growth. The grain size distributions of solders obtained from simulations were narrower than that of normal grain growth. It was found that the phase composition of solder is important in determining grain growth behavior.

  17. The tensile strength characteristics study of the laser welds of biological tissue using the nanocomposite solder

    Science.gov (United States)

    Rimshan, I. B.; Ryabkin, D. I.; Savelyev, M. S.; Zhurbina, N. N.; Pyanov, I. V.; Eganova, E. M.; Pavlov, A. A.; Podgaetsky, V. M.; Ichkitidze, L. P.; Selishchev, S. V.; Gerasimenko, A. Y.

    2016-04-01

    Laser welding device for biological tissue has been developed. The main device parts are the radiation system and adaptive thermal stabilization system of welding area. Adaptive thermal stabilization system provided the relation between the laser radiation intensity and the weld temperature. Using atomic force microscopy the structure of composite which is formed by the radiation of laser solder based on aqua- albuminous dispersion of multi-walled carbon nanotubes was investigated. AFM topograms nanocomposite solder are mainly defined by the presence of pores in the samples. In generally, the surface structure of composite is influenced by the time, laser radiation power and MWCNT concentration. Average size of backbone nanoelements not exceeded 500 nm. Bulk density of nanoelements was in the range 106-108 sm-3. The data of welding temperature maintained during the laser welding process and the corresponding tensile strength values were obtained. Maximum tensile strength of the suture was reached in the range 50-55°C. This temperature and the pointwise laser welding technology (point area ~ 2.5mm) allows avoiding thermal necrosis of healthy section of biological tissue and provided reliable bonding construction of weld join. In despite of the fact that tensile strength values of the samples are in the range of 15% in comparison with unbroken strips of pigskin leather. This situation corresponds to the initial stage of the dissected tissue connection with a view to further increasing of the joint strength of tissues with the recovery of tissue structure; thereby achieved ratio is enough for a medical practice in certain cases.

  18. Planetary Candidates Observed by Kepler. VII. The First Fully Uniform Catalog Based on The Entire 48 Month Dataset (Q1-Q17 DR24)

    CERN Document Server

    Coughlin, Jeffrey L; Thompson, Susan E; Rowe, Jason F; Burke, Christopher J; Latham, David W; Batalha, Natalie M; Ofir, Aviv; Quarles, Billy L; Henze, Christopher E; Wolfgang, Angie; Caldwell, Douglas A; Bryson, Stephen T; Shporer, Avi; Catanzarite, Joseph; Akeson, Rachel; Barclay, Thomas; Borucki, William J; Boyajian, Tabetha S; Campbell, Jennifer R; Christiansen, Jessie L; Girouard, Forrest R; Haas, Michael R; Howell, Steve B; Huber, Daniel; Jenkins, Jon M; Li, Jie; Patil-Sabale, Anima; Quintana, Elisa V; Ramirez, Solange; Seader, Shawn; Smith, Jeffrey C; Tenenbaum, Peter; Twicken, Joseph D; Zamudio, Khadeejah A

    2015-01-01

    We present the seventh Kepler planet candidate catalog, which is the first to be based on the entire, uniformly processed, 48 month Kepler dataset. This is the first fully automated catalog, employing robotic vetting procedures to uniformly evaluate every periodic signal detected by the Q1-Q17 Data Release 24 (DR24) Kepler pipeline. While we prioritize uniform vetting over the absolute correctness of individual objects, we find that our robotic vetting is overall comparable to, and in most cases is superior to, the human vetting procedures employed by past catalogs. This catalog is the first to utilize artificial transit injection to evaluate the performance of our vetting procedures and quantify potential biases, which are essential for accurate computation of planetary occurrence rates. With respect to the cumulative Kepler Object of Interest (KOI) catalog, we designate 1,478 new KOIs, of which 402 are dispositioned as planet candidates (PCs). Also, 237 KOIs dispositioned as false positives (FPs) in previou...

  19. VennPainter: A Tool for the Comparison and Identification of Candidate Genes Based on Venn Diagrams.

    Directory of Open Access Journals (Sweden)

    Guoliang Lin

    Full Text Available VennPainter is a program for depicting unique and shared sets of genes lists and generating Venn diagrams, by using the Qt C++ framework. The software produces Classic Venn, Edwards' Venn and Nested Venn diagrams and allows for eight sets in a graph mode and 31 sets in data processing mode only. In comparison, previous programs produce Classic Venn and Edwards' Venn diagrams and allow for a maximum of six sets. The software incorporates user-friendly features and works in Windows, Linux and Mac OS. Its graphical interface does not require a user to have programing skills. Users can modify diagram content for up to eight datasets because of the Scalable Vector Graphics output. VennPainter can provide output results in vertical, horizontal and matrix formats, which facilitates sharing datasets as required for further identification of candidate genes. Users can obtain gene lists from shared sets by clicking the numbers on the diagram. Thus, VennPainter is an easy-to-use, highly efficient, cross-platform and powerful program that provides a more comprehensive tool for identifying candidate genes and visualizing the relationships among genes or gene families in comparative analysis.

  20. VennPainter: A Tool for the Comparison and Identification of Candidate Genes Based on Venn Diagrams.

    Science.gov (United States)

    Lin, Guoliang; Chai, Jing; Yuan, Shuo; Mai, Chao; Cai, Li; Murphy, Robert W; Zhou, Wei; Luo, Jing

    2016-01-01

    VennPainter is a program for depicting unique and shared sets of genes lists and generating Venn diagrams, by using the Qt C++ framework. The software produces Classic Venn, Edwards' Venn and Nested Venn diagrams and allows for eight sets in a graph mode and 31 sets in data processing mode only. In comparison, previous programs produce Classic Venn and Edwards' Venn diagrams and allow for a maximum of six sets. The software incorporates user-friendly features and works in Windows, Linux and Mac OS. Its graphical interface does not require a user to have programing skills. Users can modify diagram content for up to eight datasets because of the Scalable Vector Graphics output. VennPainter can provide output results in vertical, horizontal and matrix formats, which facilitates sharing datasets as required for further identification of candidate genes. Users can obtain gene lists from shared sets by clicking the numbers on the diagram. Thus, VennPainter is an easy-to-use, highly efficient, cross-platform and powerful program that provides a more comprehensive tool for identifying candidate genes and visualizing the relationships among genes or gene families in comparative analysis. PMID:27120465

  1. VennPainter: A Tool for the Comparison and Identification of Candidate Genes Based on Venn Diagrams

    Science.gov (United States)

    Yuan, Shuo; Mai, Chao; Cai, Li; Murphy, Robert W.; Zhou, Wei; Luo, Jing

    2016-01-01

    VennPainter is a program for depicting unique and shared sets of genes lists and generating Venn diagrams, by using the Qt C++ framework. The software produces Classic Venn, Edwards’ Venn and Nested Venn diagrams and allows for eight sets in a graph mode and 31 sets in data processing mode only. In comparison, previous programs produce Classic Venn and Edwards’ Venn diagrams and allow for a maximum of six sets. The software incorporates user-friendly features and works in Windows, Linux and Mac OS. Its graphical interface does not require a user to have programing skills. Users can modify diagram content for up to eight datasets because of the Scalable Vector Graphics output. VennPainter can provide output results in vertical, horizontal and matrix formats, which facilitates sharing datasets as required for further identification of candidate genes. Users can obtain gene lists from shared sets by clicking the numbers on the diagram. Thus, VennPainter is an easy-to-use, highly efficient, cross-platform and powerful program that provides a more comprehensive tool for identifying candidate genes and visualizing the relationships among genes or gene families in comparative analysis. PMID:27120465

  2. Contamination profile on typical printed circuit board assemblies vs soldering process

    DEFF Research Database (Denmark)

    Conseil, Helene; Jellesen, Morten Stendahl; Ambat, Rajan

    2014-01-01

    Purpose – The purpose of this paper was to analyse typical printed circuit board assemblies (PCBAs) processed by reflow, wave or selective wave soldering for typical levels of process-related residues, resulting from a specific or combination of soldering processes. Typical solder flux residue...... structure was identified by Fourier transform infrared spectroscopy, while the concentration was measured using ion chromatography, and the electrical properties of the extracts were determined by measuring the leak current using a twin platinum electrode set-up. Localized extraction of residue was carried...

  3. Potentiodynamic polarization effect on phase and microstructure of SAC305 solder in hydrochloric acid solution

    Science.gov (United States)

    Zaini, Nurwahida Binti Mohd; Nazeri, Muhammad Firdaus Bin Mohd

    2016-07-01

    The corrosion analysis of SAC305 lead free solder was investigated in Hydrochloric acid (HCl) solution. Potentiodynamic polarization was used to polarize the SAC305. The effect of polarization on the phase and microstructure were compared to as-prepared SAC305 solder. Potentiodynamic polarization introduces mixed corrosion products on the surface of SAC305 solder. The XRD analysis confirms that the mixed corrosion products emerged on the surface after polarization by formation of SnO and SnO2 of which confirmed that dissolution of Sn was dominant during polarization. Microstructure analysis reveal the presence of gap and porosities produced limits the protection offered by the passivation film.

  4. Performances of PIXE and nuclear microprobes for the study of gold soldering processes

    International Nuclear Information System (INIS)

    Our work undertaken ten years ago in order to understand the procedures used in antiquity to realize tiny solders on gold jewellery artefacts has been extended to the rediscovery, in laboratory, of possible antique recipes and their improvements for modern purposes. We are now able to put forward economical processes to solder pieces of gold at low temperatures using bulk brazing materials and diffusion bonding processes by local diffusion of cadmium or rapid diffusion of silicon along grain boundaries. The performances of PIXE and nuclear microprobes to investigate materials and solders are discussed. (orig.)

  5. Generation and Characterization of Live Attenuated Influenza A(H7N9 Candidate Vaccine Virus Based on Russian Donor of Attenuation.

    Directory of Open Access Journals (Sweden)

    Svetlana Shcherbik

    Full Text Available Avian influenza A (H7N9 virus has emerged recently and continues to cause severe disease with a high mortality rate in humans prompting the development of candidate vaccine viruses. Live attenuated influenza vaccines (LAIV are 6:2 reassortant viruses containing the HA and NA gene segments from wild type influenza viruses to induce protective immune responses and the six internal genes from Master Donor Viruses (MDV to provide temperature sensitive, cold-adapted and attenuated phenotypes.LAIV candidate A/Anhui/1/2013(H7N9-CDC-LV7A (abbreviated as CDC-LV7A, based on the Russian MDV, A/Leningrad/134/17/57 (H2N2, was generated by classical reassortment in eggs and retained MDV temperature-sensitive and cold-adapted phenotypes. CDC-LV7A had two amino acid substitutions N123D and N149D (H7 numbering in HA and one substitution T10I in NA. To evaluate the role of these mutations on the replication capacity of the reassortants in eggs, the recombinant viruses A(H7N9RG-LV1 and A(H7N9RG-LV2 were generated by reverse genetics. These changes did not alter virus antigenicity as ferret antiserum to CDC-LV7A vaccine candidate inhibited hemagglutination by homologous A(H7N9 virus efficiently. Safety studies in ferrets confirmed that CDC-LV7A was attenuated compared to wild-type A/Anhui/1/2013. In addition, the genetic stability of this vaccine candidate was examined in eggs and ferrets by monitoring sequence changes acquired during virus replication in the two host models. No changes in the viral genome were detected after five passages in eggs. However, after ten passages additional mutations were detected in the HA gene. The vaccine candidate was shown to be stable in the ferret model; post-vaccination sequence data analysis showed no changes in viruses collected in nasal washes present at day 5 or day 7.Our data indicate that the A/Anhui/1/2013(H7N9-CDC-LV7A reassortant virus is a safe and genetically stable candidate vaccine virus that is now available for

  6. Evolution of microstructure, thermal and creep properties of Ni-doped Sn–0.5Ag–0.7Cu low-Ag solder alloys for electronic applications

    International Nuclear Information System (INIS)

    Highlights: • Novel SAC (0507) solder alloy with (0.05–0.1 wt.%) Ni additions were systematically investigated. • The 0.05Ni-containing sample exhibited a drastically reduced undercooling to be 6.3 °C. • Improved creep resistance and creep–rupture life of SAC (0507)–0.05Ni was due to the fine dispersion of IMCs. - Abstract: For development of lead-free solder for advance electrical components, the correlation of microstructure with thermal and creep properties of novel Ni-doped Sn–0.5Ag–0.7Cu (SAC (0507)) lead free solders has been investigated. Results showed that addition of 0.05Ni into the lead-free SAC (0507) solder led to the microstructural refinement, more uniform distribution of the Ag3Sn, (Cu,Ni)6Sn5 intermetallic compounds (IMCs) and small primary β-Sn grains. However, the SAC (0507)–0.1Ni alloy has relatively high fraction of the primary β-Sn phase and the IMCs appeared coarse within the matrix compared with the other examined alloys. DSC results showed that the addition of Ni did not produce any significant effect on the melting behavior. Interestingly, 0.05 wt.% Ni addition exhibited a drastically reduced undercooling to be 6.3 °C. In terms of creep behavior, the SAC (0507)–0.05Ni gave the highest creep resistance due to the fine dispersion of IMCs. Furthermore, 0.05 wt.% Ni addition can evidently increase the creep–rupture life, about 2.0 times greater than that of the baseline SAC (0507) and approximately 5.0 times better than that of SAC (0507)–0.1Ni solder. Meanwhile, the SAC (0507)–0.1Ni alloy shows lower creep resistance which is mainly attributable to smaller volume fraction of the precipitate phases. Based on the obtained stress exponents and activation energies, it is proposed that the dominant deformation mechanism in SAC (0507) solders is dislocation climb over the whole temperature range investigated

  7. Solid-state reactions between Sn-20.0 wt.%In-x wt.%Zn solders and Ag and Ni substrates

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Shih-kang [Department of Materials Science and Engineering, National Cheng Kung University, Tainan 701, Taiwan (China); Promotion Center for Global Materials Research, National Cheng Kung University, Tainan 701, Taiwan (China); Center for Micro/Nano Science and Technology, National Cheng Kung University, Tainan 701, Taiwan (China); Chang, Ru-Bo [Department of Chemical Engineering, National Tsing Hua University, Hsinchu 300, Taiwan (China); Chen, Sinn-wen, E-mail: swchen@mx.nthu.edu.tw [Department of Chemical Engineering, National Tsing Hua University, Hsinchu 300, Taiwan (China); Tsai, Ming-yueh [Department of Materials Science and Engineering, National Cheng Kung University, Tainan 701, Taiwan (China); Hsu, Chia-ming [Department of Chemical Engineering, National United University, Miaoli 360, Taiwan (China)

    2015-03-15

    The Sn-20 wt.%In (Sn–20In) alloy is a promising base material for low-temperature Pb-free solders. Zn is usually added in solders to reduce the extent of undercooling during reflow, while Ag and Ni are commonly seen under bump metallurgy in contact with solder in electronic products. In this study, solid-state reactions at 150 °C between Zn-doped Sn–20In solders and Ag and Ni substrates are investigated. In Sn–20In–xZn/Ag couples, when the Zn-doping level is low (x ≤ 1.0), the reaction path is γ-InSn{sub 4}/ζ-AgZn/ζ-(Ag,In)/ζ-AgZn/Ag, that the ζ-AgZn layer near the solder has non-uniform composition, the ζ-(Ag,In) layer has a porous microstructure, and the ζ-AgZn phase near the substrate is composed of small grains. When the Zn doping level is high (x ≥ 2.0), the reaction path becomes γ-InSn{sub 4}/ε-AgZn{sub 3}/γ-Ag{sub 5}Zn{sub 8}/ζ-AgZn/Ag, that all intermetallic compounds (IMCs) are planar and neither Sn nor In participate in the reactions. Although the reactions are very sensitive to Zn contents, the overall thicknesses of IMCs do not vary much with different Zn-doping levels. In Sn–20In–xZn/Ni couples, the planar Ni{sub 5}Zn{sub 21} phase is the only reaction product with a very slow growth rate. The interfacial liquation in Sn–20In/Ni contacts can be fully mitigated with a minor Zn addition of 0.5 wt.%. - Highlights: • Sn–20In–xZn/Ag and Sn–20In–xZn/Ag interfacial reactions at 150 °C were investigated. • Sn–20In–xZn/Ag reactions show strong dependence on Zn-doping levels. • Ni{sub 5}Zn{sub 21} is the only product with a very slow growth rate in Sn–20In–xZn/Ni couples. • Ni is an effective diffusion barrier for Sn–20In–xZn Pb-free solders.

  8. Solid-state reactions between Sn-20.0 wt.%In-x wt.%Zn solders and Ag and Ni substrates

    International Nuclear Information System (INIS)

    The Sn-20 wt.%In (Sn–20In) alloy is a promising base material for low-temperature Pb-free solders. Zn is usually added in solders to reduce the extent of undercooling during reflow, while Ag and Ni are commonly seen under bump metallurgy in contact with solder in electronic products. In this study, solid-state reactions at 150 °C between Zn-doped Sn–20In solders and Ag and Ni substrates are investigated. In Sn–20In–xZn/Ag couples, when the Zn-doping level is low (x ≤ 1.0), the reaction path is γ-InSn4/ζ-AgZn/ζ-(Ag,In)/ζ-AgZn/Ag, that the ζ-AgZn layer near the solder has non-uniform composition, the ζ-(Ag,In) layer has a porous microstructure, and the ζ-AgZn phase near the substrate is composed of small grains. When the Zn doping level is high (x ≥ 2.0), the reaction path becomes γ-InSn4/ε-AgZn3/γ-Ag5Zn8/ζ-AgZn/Ag, that all intermetallic compounds (IMCs) are planar and neither Sn nor In participate in the reactions. Although the reactions are very sensitive to Zn contents, the overall thicknesses of IMCs do not vary much with different Zn-doping levels. In Sn–20In–xZn/Ni couples, the planar Ni5Zn21 phase is the only reaction product with a very slow growth rate. The interfacial liquation in Sn–20In/Ni contacts can be fully mitigated with a minor Zn addition of 0.5 wt.%. - Highlights: • Sn–20In–xZn/Ag and Sn–20In–xZn/Ag interfacial reactions at 150 °C were investigated. • Sn–20In–xZn/Ag reactions show strong dependence on Zn-doping levels. • Ni5Zn21 is the only product with a very slow growth rate in Sn–20In–xZn/Ni couples. • Ni is an effective diffusion barrier for Sn–20In–xZn Pb-free solders

  9. Stochastic Dynamics of the Multi-State Voter Model over a Network based on Interacting Cliques and Zealot Candidates

    CERN Document Server

    Palombi, Filippo

    2013-01-01

    The stochastic dynamics of the multi-state voter model is investigated on a class of complex networks made of non-overlapping cliques, each hosting a political candidate and interacting with the others via Erd\\H{o}s-R\\'enyi links. Numerical simulations of the model are interpreted in terms of an ad-hoc mean field theory, specifically tuned to resolve the inter/intra-clique interactions. Under a proper definition of the thermodynamic limit (with the average degree of the agents kept fixed while increasing the network size), the model is found to display the empirical scaling discovered by Fortunato and Castellano (2007) [1] and the vote distribution resembles qualitatively that observed in Brazilian elections.

  10. Predicted Coverage and Immuno-Safety of a Recombinant C-Repeat Region Based Streptococcus pyogenes Vaccine Candidate.

    Science.gov (United States)

    McNeilly, Celia; Cosh, Samantha; Vu, Therese; Nichols, Jemma; Henningham, Anna; Hofmann, Andreas; Fane, Anne; Smeesters, Pierre R; Rush, Catherine M; Hafner, Louise M; Ketheesan, Natkuman; Sriprakash, Kadaba S; McMillan, David J

    2016-01-01

    The C-terminal region of the M-protein of Streptococcus pyogenes is a major target for vaccine development. The major feature is the C-repeat region, consisting of 35-42 amino acid repeat units that display high but not perfect identity. SV1 is a S. pyogenes vaccine candidate that incorporates five 14mer amino acid sequences (called J14i variants) from differing C-repeat units in a single recombinant construct. Here we show that the J14i variants chosen for inclusion in SV1 are the most common variants in a dataset of 176 unique M-proteins. Murine antibodies raised against SV1 were shown to bind to each of the J14i variants present in SV1, as well as variants not present in the vaccine. Antibodies raised to the individual J14i variants were also shown to bind to multiple but different combinations of J14i variants, supporting the underlying rationale for the design of SV1. A Lewis Rat Model of valvulitis was then used to assess the capacity of SV1 to induce deleterious immune response associated with rheumatic heart disease. In this model, both SV1 and the M5 positive control protein were immunogenic. Neither of these antibodies were cross-reactive with cardiac myosin or collagen. Splenic T cells from SV1/CFA and SV1/alum immunized rats did not proliferate in response to cardiac myosin or collagen. Subsequent histological examination of heart tissue showed that 4 of 5 mice from the M5/CFA group had valvulitis and inflammatory cell infiltration into valvular tissue, whereas mice immunised with SV1/CFA, SV1/alum showed no sign of valvulitis. These results suggest that SV1 is a safe vaccine candidate that will elicit antibodies that recognise the vast majority of circulating GAS M-types. PMID:27310707

  11. Effect of Surface Finish of Substrate on Mechanical Reliability of in-48SN Solder Joints in Moems Package

    CERN Document Server

    Koo, Ja-Myeong

    2007-01-01

    Interfacial reactions and shear properties of the In-48Sn (in wt.%) ball grid array (BGA) solder joints after bonding were investigated with four different surface finishes of the substrate over an underlying Cu pad: electroplated Ni/Au (hereafter E-NG), electroless Ni/immersion Au (hereafter ENIG), immersion Ag (hereafter I-Ag) and organic solderability preservative (hereafter OSP). During bonding, continuous AuIn2, Ni3(Sn,In)4 and Cu6(Sn,In)5 intermetallic compound (IMC) layers were formed at the solder/E-NG, solder/ENIG and solder/OSP interface, respectively. The interfacial reactions between the solder and I-Ag substrate during bonding resulted in the formation of Cu6(Sn,In)5 and Cu(Sn,In)2 IMCs with a minor Ag element. The In-48Sn/I-Ag solder joint showed the best shear properties among the four solder joints after bonding, whereas the solder/ENIG solder joint exhibited the weakest mechanical integrity.

  12. 化学镀可焊性锡基合金的研究进展%Progress of research on electroless plating of solderable tin alloy

    Institute of Scientific and Technical Information of China (English)

    赵国鹏; 樊江莉; 温青

    2001-01-01

    本文综述了近10年来化学镀可焊性锡基合金的研究现状及动态。列举了4种不同镀液体系的典型配方及工艺,并对化学镀锡合金的未来发展提出了建议。%Current status and prospect of solderable electroless tin alloy plating were summarized with 18 references published in the recent decade. Four traditional plating solutions based on chloride, fluoboric, alkyl sulfonate and ethane sulfonate were exemplified. Suggestions were presented about the develoment of electroless plating of solderable tin alloy.

  13. Experimental investigations on the soldering performances of the joints for Bi-2223/Ag tapes

    Energy Technology Data Exchange (ETDEWEB)

    Zou, Chunlong, E-mail: clzou@ipp.ac.cn; Son, Yuntao; Huang, Xiongyi; Liu, Chenglian; Khan, Shahab Ud-Din; Weibin, Xi; Kun, Lu

    2015-01-15

    Highlights: • Bi-2223/Ag jointed tapes were fabricated by five solder. • The solder have a different melting point. • The joint resistive were evaluated at liquid nitrogen. • Two different welding technique were compared. - Abstract: In this paper, we have fabricated Bi-2223/Ag jointed tapes and evaluated its joint resistance at liquid nitrogen temperature (77 K). The tapes were joined by the conventional resistive joint method using five kinds of solders with different melting points. The lower melting point Bi–Sn–Pb and high melting point Sn–Ag–Cu solders have lower joint resistances. In addition, two different joining processes were compared by joining the copper sheet. The joint resistances were measured at lower temperature and the resistance appears comparable to each other. It indicated that the direct-jointing is more effective method for high temperature superconductor (HTS) joining.

  14. Ultrasonic semi-solid coating soldering 6061 aluminum alloys with Sn-Pb-Zn alloys.

    Science.gov (United States)

    Yu, Xin-ye; Xing, Wen-qing; Ding, Min

    2016-07-01

    In this paper, 6061 aluminum alloys were soldered without a flux by the ultrasonic semi-solid coating soldering at a low temperature. According to the analyses, it could be obtained that the following results. The effect of ultrasound on the coating which promoted processes of metallurgical reaction between the components of the solder and 6061 aluminum alloys due to the thermal effect. Al2Zn3 was obtained near the interface. When the solder was in semi-solid state, the connection was completed. Ultimately, the interlayer mainly composed of three kinds of microstructure zones: α-Pb solid solution phases, β-Sn phases and Sn-Pb eutectic phases. The strength of the joints was improved significantly with the minimum shear strength approaching 101MPa. PMID:26964943

  15. Interfacial Reactions and Joint Strengths of Sn- xZn Solders with Immersion Ag UBM

    Science.gov (United States)

    Jee, Y. K.; Yu, Jin

    2010-10-01

    The solder joint microstructures of immersion Ag with Sn- xZn ( x = 0 wt.%, 1 wt.%, 5 wt.%, and 9 wt.%) solders were analyzed and correlated with their drop impact reliability. Addition of 1 wt.% Zn to Sn did not change the interface microstructure and was only marginally effective. In comparison, the addition of 5 wt.% or 9 wt.% Zn formed layers of AgZn3/Ag5Zn8 at the solder joint interface, which increased drop reliability significantly. Under extensive aging, Ag-Zn intermetallic compounds (IMCs) transformed into Cu5Zn8 and Ag3Sn, and the drop impact resistance at the solder joints deteriorated up to a point. The beneficial role of Zn on immersion Ag pads was ascribed to the formation of Ag-Zn IMC layers, which were fairly resistant to the drop impact, and to the suppression of the brittle Cu6Sn5 phase at the joint interface.

  16. Reliability Assessment of Solder Joints in Power Electronic Modules by Crack Damage Model for Wind Turbine Applications

    Directory of Open Access Journals (Sweden)

    John D. Sørensen

    2011-12-01

    Full Text Available Wind turbine reliability is an important issue for wind energy cost minimization, especially by reduction of operation and maintenance costs for critical components and by increasing wind turbine availability. To develop an optimal operation and maintenance plan for critical components, it is necessary to understand the physics of their failure and be able to develop reliability prediction models. Such a model is proposed in this paper for an IGBT power electronic module. IGBTs are critical components in wind turbine converter systems. These are multilayered devices where layers are soldered to each other and they operate at a thermal-power cycling environment. Temperature loadings affect the reliability of soldered joints by developing cracks and fatigue processes that eventually result in failure. Based on Miner’s rule a linear damage model that incorporates a crack development and propagation processes is discussed. A statistical analysis is performed for appropriate model parameter selection. Based on the proposed model, a layout for component life prediction with crack movement is described in details.

  17. Processing and Characterization of Device Solder Interconnection and Module Attachment for Power Electronics Modules

    OpenAIRE

    Haque, Ashim Shatil

    1999-01-01

    Processing and Characterization of Device Solder Interconnection and Module Attachment for Power Electronics Modules by Shatil Haque Committee Chairman: Dr. Guo-Quan Lu Materials Engineering and Science Department (ABSTRACT) This research is focused on the processing of an innovative three-dimensional packaging architecture for power electronics building blocks with soldered device interconnections and subsequent characterization of the module's critical interfaces. A low-co...

  18. Thermomechanical cycling investigation of CU particulate and NITI reinforced lead-free solder

    OpenAIRE

    Horton, W. Scott.

    2006-01-01

    In todayâ s Flip Chip (FC) and Ball Grid Array (BGA) electronic packages solder joints provide both the electrical as well as the mechanical connections between the silicon chip and the substrate. Due to coefficient of thermal expansion (CTE) differences between the chip and substrate the solder joints undergo thermomechanical stresses and strains as an electronic package is heated and cooled with power on/off cycles. Advances in chip designs result in chips that are larger, run hotter and d...

  19. GC-MS Based Plasma Metabolomics for Identification of Candidate Biomarkers for Hepatocellular Carcinoma in Egyptian Cohort.

    Directory of Open Access Journals (Sweden)

    Mohammad R Nezami Ranjbar

    Full Text Available This study evaluates changes in metabolite levels in hepatocellular carcinoma (HCC cases vs. patients with liver cirrhosis by analysis of human blood plasma using gas chromatography coupled with mass spectrometry (GC-MS. Untargeted metabolomic analysis of plasma samples from participants recruited in Egypt was performed using two GC-MS platforms: a GC coupled to single quadruple mass spectrometer (GC-qMS and a GC coupled to a time-of-flight mass spectrometer (GC-TOFMS. Analytes that showed statistically significant changes in ion intensities were selected using ANOVA models. These analytes and other candidates selected from related studies were further evaluated by targeted analysis in plasma samples from the same participants as in the untargeted metabolomic analysis. The targeted analysis was performed using the GC-qMS in selected ion monitoring (SIM mode. The method confirmed significant changes in the levels of glutamic acid, citric acid, lactic acid, valine, isoleucine, leucine, alpha tocopherol, cholesterol, and sorbose in HCC cases vs. patients with liver cirrhosis. Specifically, our findings indicate up-regulation of metabolites involved in branched-chain amino acid (BCAA metabolism. Although BCAAs are increasingly used as a treatment for cancer cachexia, others have shown that BCAA supplementation caused significant enhancement of tumor growth via activation of mTOR/AKT pathway, which is consistent with our results that BCAAs are up-regulated in HCC.

  20. Evaluation of low-residue soldering for military and commercial applications: A report from the Low-Residue Soldering Task Force

    Energy Technology Data Exchange (ETDEWEB)

    Iman, R.L.; Anderson, D.J. [Sandia National Labs., Albuquerque, NM (United States); Burress, R.V. [SEHO (United States)] [and others

    1995-06-01

    The LRSTF combined the efforts of industry, military, and government to evaluate low-residue soldering processes for military and commercial applications. These processes were selected for evaluation because they provide a means for the military to support the presidential mandate while producing reliable hardware at a lower cost. This report presents the complete details and results of a testing program conducted by the LRSTF to evaluate low-residue soldering for printed wiring assemblies. A previous informal document provided details of the test plan used in this evaluation. Many of the details of that test plan are contained in this report. The test data are too massive to include in this report, however, these data are available on disk as Excel spreadsheets upon request. The main purpose of low-residue soldering is to eliminate waste streams during the manufacturing process.

  1. Evaluation of solder joint reliability in flip-chip packages during accelerated testing

    Science.gov (United States)

    Kim, Jong-Woong; Kim, Dae-Gon; Hong, Won Sik; Jung, Seung-Boo

    2005-12-01

    The microstructural investigation and thermomechanical reliability evaluation of the Sn-3.0Ag-0.5Cu solder bumped flip-chip package were carried out during the thermal shock test of the package. In the initial reaction, the reaction product between the solder and Cu mini bump of chip side was Cu6Sn5 intermetallic compound (IMC) layer, while the two phases which were (Cu,Ni)6Sn5 and (Ni,Cu)3Sn4 were formed between the solder and electroless Ni-P layer of the package side. The cracks occurred at the corner solder joints after the thermal shocks of 400 cycles. The primary failure mechanism of the solder joints in this type of package was confirmed to be thermally-activated solder fatigue failure. The premature brittle interfacial failure sometimes occurred in the package side, but nearly all of the failed packages showed the occurrence of the typical fatigue cracks. The finite-element analyses were conducted to interpret the failure mechanisms of the packages, and revealed that the cracks were induced by the accumulation of the plastic work and viscoplastic shear strains.

  2. Effect of gamma radiation on micromechanical hardness of lead-free solder joint

    International Nuclear Information System (INIS)

    Lead-free solders are important material in nano and microelectronic surface mounting technology for various applications in bio medicine, environmental monitoring, spacecraft and satellite instrumentation. Nevertheless solder joint in radiation environment needs higher reliability and resistance to any damage caused by ionizing radiations. In this study a lead-free 99.0Sn0.3Ag0.7Cu wt.% (SAC) solder joint was developed and subjected to various doses of gamma radiation to investigate the effects of the ionizing radiation to micromechanical hardness of the solder. Averaged hardness of the SAC joint was obtained from nanoindentation test. The results show a relationship between hardness values of indentations and the increment of radiation dose. Highest mean hardness, 0.2290 ± 0.0270 GPa was calculated on solder joint which was exposed to 5 Gray dose of gamma radiation. This value indicates possible radiation hardening effect on irradiated solder. The hardness gradually decreased to 0.1933 ± 0.0210 GPa and 0.1631 ± 0.0173 GPa when exposed to doses 50 and 500 gray respectively. These values are also lower than the hardness of non irradiated sample which was calculated as 0.2084 ± 0.0.3633 GPa indicating possible radiation damage and needs further related atomic dislocation study

  3. Wall-slip effects in SnAgCu solder pastes used in electronics assembly applications

    International Nuclear Information System (INIS)

    Solder paste is the most important strategic bonding material used in the assembly of surface mount components in electronics manufacturing. As the trend towards miniaturisation of electronic products continues, there is an increasing demand for better understanding of the flow and deformation that is, the rheological behaviour of solder paste formulations. Wall slip plays an important role in characterising the flow behaviour of solder paste materials. The problem of wall slip arises due to the various attractive and repulsive forces acting between the solder particles and the walls of the measuring geometry. These interactions could lead to the presence of a thin solvent layer adjacent to the wall, which gives rise to slippage. In rheological measurements, slip effects can generally be avoided by using roughened surfaces for measuring geometries. In this paper, a novel technique is developed to study the effect of wall slip in the rheological measurements of lead-free solder paste. The viscosity and oscillatory data obtained for three different solder paste samples (from measuring geometries of different surface roughness) have been analysed and compared. In viscosity measurements, slip effects were dominant at low shear rates and the use of serrated surfaces was found to be quite effective in minimizing slip effects. Oscillatory measurements were also affected by roughening the surfaces of measuring geometries.

  4. Rheological characterisation and printing performance of Sn/Ag/Cu solder pastes

    International Nuclear Information System (INIS)

    Lead-free solder paste printing process accounts for majority of the assembly defects in the electronic manufacturing industry. The study investigates rheological behaviour and stencil printing performance of the lead-free solder pastes (Sn/Ag/Cu). Oscillatory stress sweep test was carried out to study the visco-elastic behaviour of the lead-free solder pastes. The visco-elastic behaviour of the paste encompasses solid and liquid characteristic of the paste, which could be used to study the flow behaviour experienced by the pastes during the stencil printing process. From this study, it was found that the solid characteristics (G') is higher than the liquid characteristic (G'') for the pastes material. In addition, the results from the study showed that the solder paste with a large G' = G'' has a higher cohesiveness resulting in poor withdrawal of the paste during the stencil printing process. The phase angles (δ) was used to correlate the quality of the dense suspensions to the formulation of solder paste materials. This study has revealed the value of having a rheological measurement for explaining and characterising solder pastes for stencil printing. As the demand for lead free pastes increases rheological measurements can assist with the formulation or development of new pastes.

  5. Candidate Gene Identification with SNP Marker-Based Fine Mapping of Anthracnose Resistance Gene Co-4 in Common Bean.

    Directory of Open Access Journals (Sweden)

    Andrew J Burt

    Full Text Available Anthracnose, caused by Colletotrichum lindemuthianum, is an important fungal disease of common bean (Phaseolus vulgaris. Alleles at the Co-4 locus confer resistance to a number of races of C. lindemuthianum. A population of 94 F4:5 recombinant inbred lines of a cross between resistant black bean genotype B09197 and susceptible navy bean cultivar Nautica was used to identify markers associated with resistance in bean chromosome 8 (Pv08 where Co-4 is localized. Three SCAR markers with known linkage to Co-4 and a panel of single nucleotide markers were used for genotyping. A refined physical region on Pv08 with significant association with anthracnose resistance identified by markers was used in BLAST searches with the genomic sequence of common bean accession G19833. Thirty two unique annotated candidate genes were identified that spanned a physical region of 936.46 kb. A majority of the annotated genes identified had functional similarity to leucine rich repeats/receptor like kinase domains. Three annotated genes had similarity to 1, 3-β-glucanase domains. There were sequence similarities between some of the annotated genes found in the study and the genes associated with phosphoinositide-specific phosphilipases C associated with Co-x and the COK-4 loci found in previous studies. It is possible that the Co-4 locus is structured as a group of genes with functional domains dominated by protein tyrosine kinase along with leucine rich repeats/nucleotide binding site, phosphilipases C as well as β-glucanases.

  6. Investigation of electrochemical migration on Sn-0.7Cu-0.3Ag-0.03P-0.005Ni solder alloy in HNO{sub 3} solution

    Energy Technology Data Exchange (ETDEWEB)

    Sarveswaran, C.; Othman, N. K. [School of Applied Physics, Faculty of Science and Technology, Universiti Kebangsaan Malaysia, 43600, Bangi, Selangor (Malaysia); Ali, M. Yusuf Tura; Ani, F. Che; Samsudin, Z. [Jabil Circuit Sdn Bhd, Bayan Lepas Industrial Park, 11900, Penang (Malaysia)

    2015-09-25

    Current issue in lead-free solder in term of its reliability is still under investigation. This high impact research attempts to investigate the electrochemical migration (ECM) on Sn-0.7Cu-0.3Ag-0.03P-0.005Ni solder alloy by Water Drop Test (WDT) in different concentration of HNO{sub 3} solution. The concentration of HNO{sub 3} solution used in this research was 0.05, 0.10, 0.50 and 1M. Optical Microscope (OM), Field Emission Scanning Electron Microscope (FESEM) and Energy Dispersive X-Ray Analysis (EDX) were carried out in order to analysis the ECM behavior based on the growth of dendrite formation after WDT. In general, the results demonstrated that dendrite growth is faster in higher concentration compared with low concentration of HNO{sub 3}. The concentration of HNO{sub 3} solution used has a strong correlation with Mean-Time-To-Failure (MTTF). As the concentration of HNO{sub 3} increases, the MTTF value decreases. Based on the MTTF results the solder alloy in 1M HNO{sub 3} solution is most susceptible to ECM. SnO{sub 2} forms as a corrosion by-product in the samples proved by EDX analysis. The solder alloy poses a high reliability risk in microelectronic devices during operation in 1M HNO{sub 3} solution.

  7. Dominant effects of Sn orientation on serrated cathode dissolution and resulting failure in actual solder joints under electromigration

    Energy Technology Data Exchange (ETDEWEB)

    Yang, T.L.; Yu, J.J.; Li, C.C.; Lin, Y.F.; Kao, C.R., E-mail: crkao@ntu.edu.tw

    2015-04-05

    Highlights: • Excessive serrated cathode dissolution strongly depends on the Sn grain orientation. • Sn grain orientation is a dominant factor that controls the direction of the serrated teeth. • Producing joints with fine Sn grains is one of the approaches to improve the reliability against current-induced failures in solder joints. - Abstract: Excessive metal dissolution is one of the major electromigration-induced degradation mechanisms in interconnects, and it often produces a distinctive serrated cathode interface with most of the serrated teeth inclined toward a specific direction. In this study, actual flip-chip solder joints were systematically analyzed to understand this highly interesting morphology. It was unequivocally established that the Sn grain orientation is a dominant factor that controls the direction of the serrated teeth. When the c-axis of a Sn grain was nearly parallel to the electron flow direction, serrated dissolution occurred, with the serrated teeth inclined toward the c-axis. These observations were rationalized based on the diffusion anisotropy of Cu in Sn.

  8. Dominant effects of Sn orientation on serrated cathode dissolution and resulting failure in actual solder joints under electromigration

    International Nuclear Information System (INIS)

    Highlights: • Excessive serrated cathode dissolution strongly depends on the Sn grain orientation. • Sn grain orientation is a dominant factor that controls the direction of the serrated teeth. • Producing joints with fine Sn grains is one of the approaches to improve the reliability against current-induced failures in solder joints. - Abstract: Excessive metal dissolution is one of the major electromigration-induced degradation mechanisms in interconnects, and it often produces a distinctive serrated cathode interface with most of the serrated teeth inclined toward a specific direction. In this study, actual flip-chip solder joints were systematically analyzed to understand this highly interesting morphology. It was unequivocally established that the Sn grain orientation is a dominant factor that controls the direction of the serrated teeth. When the c-axis of a Sn grain was nearly parallel to the electron flow direction, serrated dissolution occurred, with the serrated teeth inclined toward the c-axis. These observations were rationalized based on the diffusion anisotropy of Cu in Sn

  9. Serum-free microcarrier based production of replication deficient Influenza vaccine candidate virus lacking NS1 using Vero cells

    Directory of Open Access Journals (Sweden)

    Yan Mylene L

    2011-08-01

    Full Text Available Abstract Background Influenza virus is a major health concern that has huge impacts on the human society, and vaccination remains as one of the most effective ways to mitigate this disease. Comparing the two types of commercially available Influenza vaccine, the live attenuated virus vaccine is more cross-reactive and easier to administer than the traditional inactivated vaccines. One promising live attenuated Influenza vaccine that has completed Phase I clinical trial is deltaFLU, a deletion mutant lacking the viral Nonstructural Protein 1 (NS1 gene. As a consequence of this gene deletion, this mutant virus can only propagate effectively in cells with a deficient interferon-mediated antiviral response. To demonstrate the manufacturability of this vaccine candidate, a batch bioreactor production process using adherent Vero cells on microcarriers in commercially available animal-component free, serum-free media is described. Results Five commercially available animal-component free, serum-free media (SFM were evaluated for growth of Vero cells in agitated Cytodex 1 spinner flask microcarrier cultures. EX-CELL Vero SFM achieved the highest cell concentration of 2.6 × 10^6 cells/ml, whereas other SFM achieved about 1.2 × 10^6 cells/ml. Time points for infection between the late exponential and stationary phases of cell growth had no significant effect in the final virus titres. A virus yield of 7.6 Log10 TCID50/ml was achieved using trypsin concentration of 10 μg/ml and MOI of 0.001. The Influenza vaccine production process was scaled up to a 3 liter controlled stirred tank bioreactor to achieve a cell density of 2.7 × 10^6 cells/ml and virus titre of 8.3 Log10 TCID50/ml. Finally, the bioreactor system was tested for the production of the corresponding wild type H1N1 Influenza virus, which is conventionally used in the production of inactivated vaccine. High virus titres of up to 10 Log10 TCID50/ml were achieved. Conclusions We describe for the

  10. Selection and validation of potato candidate genes for maturity corrected resistance to Phytophthora infestans based on differential expression combined with SNP association and linkage mapping

    Directory of Open Access Journals (Sweden)

    Meki Shehabu Muktar

    2015-09-01

    Full Text Available Late blight of potato (Solanum tuberosum L. caused by the oomycete Phytophthora infestans (Mont. de Bary, is one of the most important bottlenecks of potato production worldwide. Cultivars with high levels of durable, race unspecific, quantitative resistance are part of a solution to this problem. However, breeding for quantitative resistance is hampered by the correlation between resistance and late plant maturity, which is an undesirable agricultural attribute. The objectives of our research are (i the identification of genes that condition quantitative resistance to P. infestans not compromised by late plant maturity and (ii the discovery of diagnostic single nucleotide polymorphism (SNP markers to be used as molecular tools to increase efficiency and precision of resistance breeding. Twenty two novel candidate genes were selected based on comparative transcript profiling by SuperSAGE (serial analysis of gene expression in groups of plants with contrasting levels of maturity corrected resistance (MCR. Reproducibility of differential expression was tested by quantitative real time PCR and allele specific pyrosequencing in four new sets of genotype pools with contrasting late blight resistance levels, at three infection time points and in three independent infection experiments. Reproducibility of expression patterns ranged from 28% to 97%. Association mapping in a panel of 184 tetraploid cultivars identified SNPs in five candidate genes that were associated with MCR. These SNPs can be used in marker-assisted resistance breeding. Linkage mapping in two half-sib families (n = 111 identified SNPs in three candidate genes that were linked with MCR. The differentially expressed genes that showed association and/or linkage with MCR putatively function in phytosterol synthesis, fatty acid synthesis, asparagine synthesis, chlorophyll synthesis, cell wall modification and in the response to pathogen elicitors.

  11. Evaluating the Impact of Dwell Time on Solder Interconnect Durability Under Bending Loads

    Science.gov (United States)

    Menon, Sandeep; Osterman, Michael; Pecht, Michael

    2015-11-01

    With the increasing portability and miniaturization of modern-day electronics, the mechanical robustness of these systems has become more of a concern. Existing standards for conducting mechanical durability tests of electronic assemblies include bend, shock/drop, vibration, and torsion. Although these standards provide insights into both cyclic fatigue and overstress damage incurred in solder interconnects (widely regarded as the primary mode of failure in electronic assemblies), they fail to address the impact of time- dependent (creep) behavior due to sustained mechanical loads on solder interconnect durability. It has been seen in previous studies that solder durability under thermal cycling loads is inversely proportional to the dwell time or hold time at either temperature extreme of the imposed temperature cycle. Fatigue life models, which include dwell time, have been developed for solder interconnects subject to temperature cycling. However, the fatigue life models that have been developed in the literature for solder interconnects under mechanical loads fail to address the influence of the duration of loading. In this study, solder interconnect test vehicles were subjected to cyclic mechanical bending with various dwell times in order to understand the impact of the duration of mechanical loads on solder interconnect durability. The solder interconnects examined in this study were formed with 2512 resistor packages using various solder compositions [tin-lead (Sn-Pb) and 96.5Sn-3Ag-0.5Cu (SAC305)]. To evaluate the impact of dwell time, the boards were tested with 0 s, 60 s, and 300 s of dwell time at both extremes of the loading profile. It was observed that an increase in the dwell time of the loading profile resulted in a decrease in the characteristic life of the solder interconnects. The decrease in fatigue life was attributed to increased creep damage as identified using finite-element simulations. An energy partitioning approach was then used to

  12. Transcriptomic identification of candidate genes involved in sunflower responses to chilling and salt stresses based on cDNA microarray analysis

    Directory of Open Access Journals (Sweden)

    Paniego Norma

    2008-01-01

    Full Text Available Abstract Background Considering that sunflower production is expanding to arid regions, tolerance to abiotic stresses as drought, low temperatures and salinity arises as one of the main constrains nowadays. Differential organ-specific sunflower ESTs (expressed sequence tags were previously generated by a subtractive hybridization method that included a considerable number of putative abiotic stress associated sequences. The objective of this work is to analyze concerted gene expression profiles of organ-specific ESTs by fluorescence microarray assay, in response to high sodium chloride concentration and chilling treatments with the aim to identify and follow up candidate genes for early responses to abiotic stress in sunflower. Results Abiotic-related expressed genes were the target of this characterization through a gene expression analysis using an organ-specific cDNA fluorescence microarray approach in response to high salinity and low temperatures. The experiment included three independent replicates from leaf samples. We analyzed 317 unigenes previously isolated from differential organ-specific cDNA libraries from leaf, stem and flower at R1 and R4 developmental stage. A statistical analysis based on mean comparison by ANOVA and ordination by Principal Component Analysis allowed the detection of 80 candidate genes for either salinity and/or chilling stresses. Out of them, 50 genes were up or down regulated under both stresses, supporting common regulatory mechanisms and general responses to chilling and salinity. Interestingly 15 and 12 sequences were up regulated or down regulated specifically in one stress but not in the other, respectively. These genes are potentially involved in different regulatory mechanisms including transcription/translation/protein degradation/protein folding/ROS production or ROS-scavenging. Differential gene expression patterns were confirmed by qRT-PCR for 12.5% of the microarray candidate sequences. Conclusion

  13. Intermetallic compound formation at Sn-3.0Ag-0.5Cu-1.0Zn lead-free solder alloy/Cu interface during as-soldered and as-aged conditions

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Feng-Jiang [Department of Materials Science and Engineering, Shanghai University of Engineering Science, Shanghai 201620 (China)]. E-mail: wangfjy@yahoo.com.cn; Yu, Zhi-Shui [Department of Materials Science and Engineering, Shanghai University of Engineering Science, Shanghai 201620 (China); Qi, Kai [Department of Materials Science and Engineering, Shanghai University of Engineering Science, Shanghai 201620 (China)

    2007-07-12

    Intermetallic formations of Sn-3.0Ag-0.5Cu solder alloy with additional 1.0 wt% Zn were investigated for Cu-substrate during soldering and isothermal aging. During soldering condition, the Cu{sub 5}Zn{sub 8} compound with granular-type morphology is the interfacial IMC for Sn-3.0Ag-0.5Cu-1.0Zn solder, while the Cu{sub 6}Sn{sub 5} compound with scallop-type morphology is the interfacial IMC for Sn-3.0Ag-0.5Cu solder. During thermal aging, the final interfacial structure for Sn-3.0Ag-0.5Cu-1.0Zn solder is solder/Cu{sub 5}Zn{sub 8}/Cu{sub 6}Sn{sub 5}/Cu{sub 3}Sn/Cu, different from the solder/Cu{sub 6}Sn{sub 5}/Cu{sub 3}Sn/Cu for Sn-3.0Ag-0.5Cu solder. The thickness of Cu-Sn IMC layers increases, while the thickness of Cu{sub 5}Zn{sub 8} compound layer decreases with increasing aging time due to the decomposition of the Cu{sub 5}Zn{sub 8} layer by the diffusion of Cu and Zn atoms into the solder and Cu{sub 6}Sn{sub 5} at higher aging temperature. For Sn-3.0Ag-0.5Cu-1.0Zn solder, at higher aging temperature of 150 or 175 {sup o}C, with the formation of Cu{sub 3}Sn at Cu{sub 6}Sn{sub 5}/Cu, Kirkendall voids can be observed at the interface of Cu{sub 3}Sn/Cu.

  14. Subunit influenza vaccine candidate based on CD154 fused to HAH5 increases the antibody titers and cellular immune response in chickens.

    Science.gov (United States)

    Pose, Alaín González; Gómez, Julia Noda; Sánchez, Alina Venereo; Redondo, Armando Vega; Rodríguez, Elsa Rodríguez; Seguí, Raquel Montesino; Ramos, Ernesto Manuel González; Moltó, María Pilar Rodríguez; Rodríguez, Elaine Santana; Cordero, Liliam Rios; Mallón, Alina Rodríguez; Nordelo, Carlos Borroto

    2011-09-28

    World Health Organization has a great concern about the spreading of avian influenza virus H5N1. To counteract its massive spread, poultry vaccination is highly recommended together with biosecurity measures. In our study, a recombinant vaccine candidate based on the fusion of extracellular segments of hemagglutinin (HA) H5 of avian influenza virus and chicken CD154 (HACD) is tested with the aim of enhancing humoral and cellular immune responses in chickens. Protein expression was carried out by transducing several mammalian cell lines with recombinant adenoviral vectors. HACD purification was assessed by three distinct purification protocols: immunoaffinity chromatography by elution at acidic pH or with a chaotropic agent and size exclusion chromatography. Humoral and cellular immune responses were measured using the hemagglutination inhibition assay and the semiquantitative real time PCR, respectively. The results showed that humoral response against HACD was significantly higher than the obtained with HA alone after booster (Pvaccine candidate against H5N1 virus outbreaks. PMID:21680114

  15. Integrating candidate metabolites and biochemical factors to elucidate the action mechanism of Xue-sai-tong injection based on (1)H NMR metabolomics.

    Science.gov (United States)

    Jiang, Miaomiao; Zhao, Xiaoping; Wang, Linli; Xu, Lei; Zhang, Yan; Li, Zheng

    2016-07-15

    A strategy of integrating candidate metabolites with crucial biochemical factors was proposed in this study to discover relevant biological functions for interpreting the action mechanism of Traditional Chinese Medicines (TCM). This approach was applied to Xue-Sai-Tong injection (XST) to reveal the action mechanism based on the metabolic response in an ischemia/reperfusion (I/R) rat model by analyzing NMR profile. Partial least squares discriminate analysis (PLS-DA) was used to compare metabolic profiles of serum samples and revealed nine metabolites altered by I/R injury could be restored to normal status (sham-operated group) under the therapy of XST. The pathway enrichment analysis suggested the metabolic changes were mainly involved in pyruvate metabolism, glycolysis, and citrate cycle. The functional roles of the candidate metabolites were further identified by Pearson correlation analysis with the key biochemical factors in serum. The results indicated pyruvate, succinate, acetate and lysine showed significant associations with the oxidative stress factors. Elevated level of pyruvate was found as an essential metabolic response for the major effect of XST against I/R injury by enhancing glycolysis and overcoming the induced reactive oxygen species (ROS). This metabolomics approach provides a better understanding of the mechanisms of TCM and helps to develop a holistic view of TCM efficacy. PMID:26862062

  16. Bonding Low-density Nanoporous Metal Foams Using Sputtered Solder

    Energy Technology Data Exchange (ETDEWEB)

    Bono, M; Cervantes, O; Akaba, C; Hamza, A; Foreman, R; Teslich, N

    2007-08-21

    A method has been developed for bonding low-density nanoporous metal foam components to a substrate using solder that is sputtered onto the surfaces. Metal foams have unusual properties that make them excellent choices for many applications, and as technologies for processing these materials are evolving, their use in industry is increasing dramatically. Metal foams are lightweight and have advantageous dynamic properties, which make them excellent choices for many structural applications. They also provide good acoustic damping, low thermal conductivity, and excellent energy absorption characteristics. Therefore, these materials are commonly used in the automotive, aerospace, construction, and biomedical industries. The synthesis of nanoporous metal foams with a cell size of less then 1 {micro}m is an emerging technology that is expected to lead to widespread application of metal foams in microdevices, such as sensors and actuators. One of the challenges to manufacturing components from metal foams is that they can be difficult to attach to other structures without degrading their properties. For example, traditional liquid adhesives cannot be used because they are absorbed into foams. The problem of bonding or joining can be particularly difficult for small-scale devices made from nanoporous foam, due to the requirement for a thin bond layer. The current study addresses this problem and develops a method of soldering a nanoporous metal foam to a substrate with a bond thickness of less than 2 {micro}m. There are many applications that require micro-scale metal foams precisely bonded to substrates. This study was motivated by a physics experiment that used a laser to drive a shock wave through an aluminum foil and into a copper foam, in order to determine the speed of the shock in the copper foam. To avoid disturbing the shock, the interface between the copper foam and the aluminum substrate had to be as thin as possible. There are many other applications that

  17. EFFECTS OF LEAD WIDTHS AND PITCHES ON RELIABILITY OF QUAD FLAT PACKAGE (QFP) SOLDERED JOINTS

    Institute of Scientific and Technical Information of China (English)

    XUE Songbai; WU Yuxiu; HAN Zongjie; WANG Jianxin

    2007-01-01

    The finite element method(FEM) is used to analyze the effects of lead widths and pitches on reliability of soldered joints. The optimum Simulation for QFP devices is also researched. The results indicate that when the lead pitches are the same, the maximum equivalent stress of the soldered joints increases with the increasing of lead widths, while the reliability of the soldered joints reduces. When the lead widths are the same, the maximum equivalent stress of the soldered joints doesn't decrease completely with the increasing of lead pitches, a minimum value of the maximum equivalent stress values exists in all the curves. Under this condition the maximum equivalent stress of the soldered joints is relatively the least, the reliability of soldered joints is high and the assembly is excellent. The simulating results indicate the best parameter: The lead width is 0.2 mm and lead pitch is 0.3 mm (the distance between two leads is 0.1 mm), which are benefited for the micromation of QFP devices now. The minimum value of the maximum equivalent stress of soldered joints exists while lead width is 0.25 mm and lead pitch is 0.35 mm (the distance between two leads is 0.1 mm), the devices can serve for a long time and the reliability is the highest, the assembly is excellent. The simulating results also indicate the fact that the lead width is 0.15 mm and lead pitch is 0.2 mm maybe the limit of QFP, which is significant for the high lead count and micromation of assembly.

  18. Effect of the Creative Drama-Based Assertiveness Program on the Assertiveness Skill of Psychological Counsellor Candidates

    Science.gov (United States)

    Gundogdu, Rezzan

    2012-01-01

    The purpose of this quasi-experimental research is to study the effects of the creative drama-based assertiveness program (CDBAP) on the assertiveness skill of Psychological Counselling and Guidance (PCG) department students. The opinions of experimental group students on the program were obtained through the CDBAP evaluation form. The sample of…

  19. A new high-throughput method utilizing porous silica-based nano-composites for the determination of partition coefficients of drug candidates.

    Science.gov (United States)

    Yu, Chih H; Tam, Kin; Tsang, Shik C

    2011-09-01

    We show that highly porous silica-based nanoparticles prepared via micro-emulsion and sol-gel techniques are stable colloids in aqueous solution. By incorporating a magnetic core into the porous silica nano-composite, it is found that the material can be rapidly separated (precipitated) upon exposure to an external magnetic field. Alternatively, the porous silica nanoparticles without magnetic cores can be equally separated from solution by applying a high-speed centrifugation. Using these silica-based nanostructures a new high-throughput method for the determination of partition coefficient for water/n-octanol is hereby described. First, a tiny quantity of n-octanol phase is pre-absorbed in the porous silica nano-composite colloids, which allows an establishment of interface at nano-scale between the adsorbed n-octanol with the bulk aqueous phase. Organic compounds added to the mixture can therefore undergo a rapid partition between the two phases. The concentration of drug compound in the supernatant in a small vial can be determined by UV-visible absorption spectroscopy. With the adaptation of a robotic liquid handler, a high-throughput technology for the determination of partition coefficients of drug candidates can be employed for drug screening in the industry based on these nano-separation skills. The experimental results clearly suggest that this new method can provide partition coefficient values of potential drug candidates comparable to the conventional shake-flask method but requires much shorter analytical time and lesser quantity of chemicals. PMID:21780284

  20. Capacitor Test, Evaluation. and Modeling Within NASA Electronic Parts and Packaging (NEPP) Program. "Why Ceramic Capacitors Fracture During Manual Soldering and How to Avoid Failures"

    Science.gov (United States)

    Teverovsky, Alexander

    2011-01-01

    Presentation discusses: (1) Why Multi-Layer Ceramic Capacitors(MLCCs) crack during manual soldering? Workmanship and parts issues. (2) Do existing qualification requirements assure crack-free soldering? MIL-spec Thermal Shock (TS) testing. MIL-spec Resistance to Soldering Heat (RSH) test. (3) What test can assure reliable soldering? Mechanical characteristics of ceramics. Comparison of three TS techniques: LND, TSD, and IWT. (4) Simulation of TS conditions.

  1. Special Education Teacher Candidate Assessment: A Review

    Science.gov (United States)

    McCall, Zach; McHatton, Patricia Alvarez; Shealey, Monika Williams

    2014-01-01

    Teacher preparation has been under intense scrutiny in recent years. In order for preparation of special education teacher candidates to remain viable, candidate assessment practices must apply practices identified in the extant literature base, while special education teacher education researchers must extend this base with rigorous efforts to…

  2. Characterization of tin crystal orientation evolution during thermal cycling in lead-free solder joints

    Science.gov (United States)

    Zhou, Bite

    To address the long term reliability of lead-free solder joints in electronic devices during thermal cycling, the fundamental understanding of deformation mechanisms was studied using polarized light optical microscopy (PLM), electron backscatter diffraction (EBSD) in scanning electron microscopy (SEM), and synchrotron X-ray diffraction (XRD). Near-eutectic Sn-3.0(wt %) Ag-0.5(wt %) Cu (SAC305) lead-free solder joints were assessed in three different package designs: low-strain plastic ball grid array (PBGA), medium-strain fine-pitch ball grid array (BGA), and high-strain wafer-level-chip-scale package (WLCSP). The effect of microstructure evolution on solder failure is correlated with dislocation slip activities. The major failure mode in lead-free solder joints during thermal cycling that causes the electrical failure of the device is cracking in the bulk Sn near the Si chip/solder interface. Microstructure and Sn grain orientation evolution usually precedes crack development. A combined approach of both statistical analysis of a large number of solder joints, and detailed studies of individual solder balls was used to investigate the causes of fracture. Sn crystal orientation evolution and its effect on deformation was characterized in solder joints with different thermal histories, and compared with those from other package designs with different effective strain levels. The relationship between the initial dominant and localized recrystallized Sn grain orientations on crack development was investigated. It is found that in the low-strain package design, cracking is strongly correlated with Sn grain orientations with the [001] direction (c-axis) nearly aligned with the chip/solder interface. But no cracks were observed in solder balls with dominant orientations that have the c-axis normal to the interface plane. In higher-strain packages, however, cracking occurred in a variety of Sn grain orientations, and even solder balls with dominant orientations that are

  3. Improving the quality of biomarker candidates in untargeted metabolomics via peak table-based alignment of comprehensive two-dimensional gas chromatography-mass spectrometry data.

    Science.gov (United States)

    Bean, Heather D; Hill, Jane E; Dimandja, Jean-Marie D

    2015-05-15

    The potential of high-resolution analytical technologies like GC×GC/TOF MS in untargeted metabolomics and biomarker discovery has been limited by the development of fully automated software that can efficiently align and extract information from multiple chromatographic data sets. In this work we report the first investigation on a peak-by-peak basis of the chromatographic factors that impact GC×GC data alignment. A representative set of 16 compounds of different chromatographic characteristics were followed through the alignment of 63 GC×GC chromatograms. We found that varying the mass spectral match parameter had a significant influence on the alignment for poorly-resolved peaks, especially those at the extremes of the detector linear range, and no influence on well-chromatographed peaks. Therefore, optimized chromatography is required for proper GC×GC data alignment. Based on these observations, a workflow is presented for the conservative selection of biomarker candidates from untargeted metabolomics analyses. PMID:25857541

  4. Mechanical strength and its variability in Bi-modified Sn-Ag-Cu solder alloy

    Directory of Open Access Journals (Sweden)

    M. Matahir

    2011-05-01

    Full Text Available Purpose: Many previous work on Sn rich Pb-free soldering had focused on the evolution, morphology and the role of interfacial intermetallic compounds (IMC layers of Cu3Sn and Cu6Sn5 on the mechanical integrity of soldered joints. However recent studies had shown that under static shearing stress, more fracture failures had been found to occur through the solder and thus indicate the significance of solder microstructures in the joint integrity. In this work, we investigated the effect of Bi substitution for Sn on the shear strength of solder joints of near eutectic SAC alloy Sn3.5Ag0.9Cu.Design/methodology/approach: Ingot alloy were prepared from pure elements and their melting characteristics were followed with thermal analyses. Copper plates were soldered together in lap joints that were subjected to shear testing in the as-soldered conditions. The microstructures were followed by SEM and EDS.Findings: Results show that failures occurred in quasi-brittle manner, with large variability. The ternary SAC alloy had average shear strength of 30 MPa better than binary eutectic Sn/Cu. Small Bi substitution of Sn up to 2 wt% lead to increased average shear strengths with maximum strengths of about 50 MPa recorded for compositions with Bi content of 0.5 to 1.5 wt%. Bi substitutions beyond 2wt% gave substantially lower strength values. The application of Weibull criteria suggest untypical high variability in strength with Webuill moduli less than 10. Higher variability in shear strengths were found in compositions containing more than 2 wt.% Bi.Research limitations/implications: Micro-structural evidence suggest that the role of Bi in increasing strength may be related to the high solubility of Bi in Sn and this would have provided some solution hardening effect. Higher Bi content however, lead to the formation Bi rich phases in the microstructure and this would have affected the mechanics of deformation thus leading to generally lower strength values

  5. Comparison of the Hydrolysis Rate of Several Polyol Ester Oils as a Candidate for Environmentally Adapted Synthetic Base Oil

    Energy Technology Data Exchange (ETDEWEB)

    Han, Du Hee [Korea Research Institute of Chemical Technology, Taejon (Korea); Masuko, Masabumi [Department of Chemical Engineering, Tokyo Institute of Technology, Tokyo (Japan)

    2001-05-01

    The hydrolysis rates of seven kinds of polyol ester base oils [POEs] of different branch shape were investigated by using a simple apparatus under a mild acidic condition. Seven polyol ester base oils were made of poly hydric alcohols of two-four valence, normal or branched fatty acids of different carbon number. p-Toluene sulfonic acid was used as an acid catalyst to accelerate the rate of hydrolysis. Partial esters and fatty acid produced by sequential hydrolysis of POEs were identified, and their concentrations were determined by the calibrated-internal standard method using Gas Chromatography. The rate constants of each step, in sequential hydrolysis, were determined by the least square method from rate equation, and the concentration of each component was compared with one another. It was shown that the rate of hydrolysis of POEs was strongly affected by the molecular structure of fatty acid, a straight chain or a branch chain, and the position of branch. The hydrolysis stability for all the POEs can be reasonably explained by the steric hindrance effect of their molecular structures as water molecule makes an attack on the carbonyl carbon of POEs. 14 refs., 8 figs., 2 tabs.

  6. Chemical wiring and soldering toward all-molecule electronic circuitry.

    Science.gov (United States)

    Okawa, Yuji; Mandal, Swapan K; Hu, Chunping; Tateyama, Yoshitaka; Goedecker, Stefan; Tsukamoto, Shigeru; Hasegawa, Tsuyoshi; Gimzewski, James K; Aono, Masakazu

    2011-06-01

    Key to single-molecule electronics is connecting functional molecules to each other using conductive nanowires. This involves two issues: how to create conductive nanowires at designated positions, and how to ensure chemical bonding between the nanowires and functional molecules. Here, we present a novel method that solves both issues. Relevant functional molecules are placed on a self-assembled monolayer of diacetylene compound. A probe tip of a scanning tunneling microscope is then positioned on the molecular row of the diacetylene compound to which the functional molecule is adsorbed, and a conductive polydiacetylene nanowire is fabricated by initiating chain polymerization by stimulation with the tip. Since the front edge of chain polymerization necessarily has a reactive chemical species, the created polymer nanowire forms chemical bonding with an encountered molecular element. We name this spontaneous reaction "chemical soldering". First-principles theoretical calculations are used to investigate the structures and electronic properties of the connection. We demonstrate that two conductive polymer nanowires are connected to a single phthalocyanine molecule. A resonant tunneling diode formed by this method is discussed. PMID:21548552

  7. Investigation of Dissolution Behavior of Metallic Substrates and Intermetallic Compound in Molten Lead-free Solders

    Science.gov (United States)

    Yen, Yee-Wen; Chou, Weng-Ting; Tseng, Yu; Lee, Chiapyng; Hsu, Chun-Lei

    2008-01-01

    This study investigates the dissolution behavior of the metallic substrates Cu and Ag and the intermetallic compound (IMC)-Ag3Sn in molten Sn, Sn-3.0Ag-0.5Cu, Sn-58Bi and Sn-9Zn (in wt.%) at 300, 270 and 240°C. The dissolution rates of both Cu and Ag in molten solder follow the order Sn > Sn-3.0Ag-0.5Cu >Sn-58Bi > Sn-9Zn. Planar Cu3Sn and scalloped Cu6Sn5 phases in Cu/solders and the scalloped Ag3Sn phase in Ag/solders are observed at the metallic substrate/solder interface. The dissolution mechanism is controlled by grain boundary diffusion. The planar Cu5Zn8 layer formed in the Sn-9Zn/Cu systems. AgZn3, Ag5Zn8 and AgZn phases are found in the Sn-9Zn/Ag system and the dissolution mechanism is controlled by lattice diffusion. Massive Ag3Sn phases dissolved into the solders and formed during solidification processes in the Ag3Sn/Sn or Sn-3.0Ag-0.5Cu systems. AgZn3 and Ag5Zn8 phases are formed at the Sn-9Zn/Ag3Sn interface. Zn atoms diffuse through Ag-Zn IMCs to form (Ag, Zn)Sn4 and Sn-rich regions between Ag5Zn8 and Ag3Sn.

  8. Formation and growth of intermetallic phases in diffusion soldered Cu/In-Bi/Cu interconnections

    International Nuclear Information System (INIS)

    The paper presents microscopy observations of Cu/Bi-22 at.%In/Cu interconnections obtained as a result of diffusion soldering process. The choice of the material as well as technological process allowed getting thermally stable joints dedicated to the electronic equipment thanks to controllable growth of intermetallic phase(s). The θ[Cu11In9] phase was present in the Cu/In-22Bi/Cu joint manufactured in the temperature range of 85-200 deg. C. Two sublayers of θ were identified; the first one, adjacent to copper substrate, contained (except for In and Cu) up to 6 at.% Bi, the second one appeared as the so-called scallops growing into liquid solder. The θ phase enriched in Bi transformed into η[Cu2In] phase. The η showed also two morphologies. The homogeneous layer of η grew at the Cu/In-Bi solder interface at 300-325 deg. C. On the other hand, islands surrounded by unreacted solder were present after soldering at 350 deg. C. The third intermetallic phase δ[Cu7In3] coexisted with η at 350 deg. C. Moreover, the solid solution of In and Bi in Cu is formed at the δ/copper substrate. All the three phases belong to the binary Cu-In equilibrium phase diagram, while Bi appears in the form of separated areas within the θ or η phase.

  9. Efficacy of a recombinant fowl pox-based Newcastle disease virus vaccine candidate against velogenic and respiratory challenge.

    Science.gov (United States)

    Taylor, J; Christensen, L; Gettig, R; Goebel, J; Bouquet, J F; Mickle, T R; Paoletti, E

    1996-01-01

    A fowl pox-based recombinant virus TROVAC-NDV (vFP96.5) was developed expressing the fusion and hemagglutinin-neuraminidase glycoproteins from a velogenic strain of Newcastle disease virus (NDV). Studies in specific-pathogen-free birds indicated that inoculation of a single dose of the recombinant led to the induction of significant levels of hemagglutination-inhibiting antibody that were maintained to 8 wk postinoculation. Further, the recombinant induced protective immunity against a combined intramuscular velogenic NDV challenge and respiratory NDV challenge. In commercial broiler chickens that were inoculated in the presence of maternally derived NDV immunity, the level of the NDV-specific humoral response was dampened, but significant levels of protection against both a lethal intramuscular NDV challenge and a fowl poxvirus challenge were obtained. PMID:8713031

  10. Synthesis and evaluation of influenza A viral neuraminidase candidate inhibitors based on a bicyclo[3.1.0]hexane scaffold.

    Science.gov (United States)

    Colombo, Cinzia; Pinto, B Mario; Bernardi, Anna; Bennet, Andrew J

    2016-07-01

    This manuscript describes a novel class of derivatives based on a bicyclo[3.1.0]hexane scaffold, proposed as mimics of sialic acid in a distorted boat conformation that is on the catalytic pathway of neuraminidases (sialidases). A general synthetic route for these constrained-ring molecules was developed using a photochemical reaction followed by a Johnson-Corey-Chaykovsky cyclopropanation. Functionalization with the goal of occupying the 150-cavity was also exploited. Inhibition assays demonstrated low micromolar inhibition against both group-1 (H5N1) and group-2 (H9N2) influenza neuraminidase subtypes, indicating good affinity for the alpha and beta sialic acid mimics and 150-cavity-targeted derivatives. These results provide a validation of a bicyclo[3.1.0]hexane scaffold as a mimic of a distorted sialic acid bound in the neuraminidase active site during catalysis. PMID:27305457

  11. GP5- Modeling and experimental investigation of the microstructural changes in the interdiffusion zone of leadfree solder joints

    Czech Academy of Sciences Publication Activity Database

    Moelans, N.; Botsis, J.; Čička, R.; Cugnoni, J.; Durga, A.; Danielewski, M.; Drápala, J.; Drienovský, M.; Guan, Y.; Harcuba, P.; Janczak-Rusch, J.; Janovec, J.; Kodentsov, A.A.; Kroupa, Aleš; Kubíček, P.; Kudyba, A.; Maleki, M.; Novakovic, R.; Nowak, R.; Ožvold, M.; Pawelkiewicz, M.; Pietrzak, K.; Pocisková Dimová, K.; Rízeková Trnková, L.; Scheller, M.; Sienicki, E.; Sobczak, N.; Sosnowska, K. K.; Toporek, G.; Vodárek, V.; Zemanová, Adéla; Zolliker, P.

    Brno : COST office, 2012 - (Kroupa, A.), s. 109-180 ISBN 978-80-905363-3-3. - ( COST MPO602. High-temperature Lead-free Solders. Vol 3) R&D Projects: GA MŠk(CZ) OC08053 Institutional support: RVO:68081723 Keywords : Leads-free solders * Modelling of diffusion processes * Phase field method * Processes on interface Subject RIV: BJ - Thermodynamics

  12. Information criterion-based clustering with order-restricted candidate profiles in short time-course microarray experiments

    Directory of Open Access Journals (Sweden)

    Zhang Baoxue

    2009-05-01

    Full Text Available Abstract Background Time-course microarray experiments produce vector gene expression profiles across a series of time points. Clustering genes based on these profiles is important in discovering functional related and co-regulated genes. Early developed clustering algorithms do not take advantage of the ordering in a time-course study, explicit use of which should allow more sensitive detection of genes that display a consistent pattern over time. Peddada et al. 1 proposed a clustering algorithm that can incorporate the temporal ordering using order-restricted statistical inference. This algorithm is, however, very time-consuming and hence inapplicable to most microarray experiments that contain a large number of genes. Its computational burden also imposes difficulty to assess the clustering reliability, which is a very important measure when clustering noisy microarray data. Results We propose a computationally efficient information criterion-based clustering algorithm, called ORICC, that also takes account of the ordering in time-course microarray experiments by embedding the order-restricted inference into a model selection framework. Genes are assigned to the profile which they best match determined by a newly proposed information criterion for order-restricted inference. In addition, we also developed a bootstrap procedure to assess ORICC's clustering reliability for every gene. Simulation studies show that the ORICC method is robust, always gives better clustering accuracy than Peddada's method and saves hundreds of times computational time. Under some scenarios, its accuracy is also better than some other existing clustering methods for short time-course microarray data, such as STEM 2 and Wang et al. 3. It is also computationally much faster than Wang et al. 3. Conclusion Our ORICC algorithm, which takes advantage of the temporal ordering in time-course microarray experiments, provides good clustering accuracy and is meanwhile much

  13. Enhanced interfacial thermal transport in pnictogen tellurides metallized with a lead-free solder alloy

    International Nuclear Information System (INIS)

    Controlling thermal transport across metal–thermoelectric interfaces is essential for realizing high efficiency solid-state refrigeration and waste-heat harvesting power generation devices. Here, the authors report that pnictogen chalcogenides metallized with bilayers of Sn96.5Ag3Cu0.5 solder and Ni barrier exhibit tenfold higher interfacial thermal conductance Γc than that obtained with In/Ni bilayer metallization. X-ray diffraction and x-ray spectroscopy indicate that reduced interdiffusion and diminution of interfacial SnTe formation due to Ni layer correlates with the higher Γc. Finite element modeling of thermoelectric coolers metallized with Sn96.5Ag3Cu0.5/Ni bilayers presages a temperature drop ΔT ∼ 22 K that is 40% higher than that obtained with In/Ni metallization. Our results underscore the importance of controlling chemical intermixing at solder–metal–thermoelectric interfaces to increase the effective figure of merit, and hence, the thermoelectric cooling efficiency. These findings should facilitate the design and development of lead-free metallization for pnictogen chalcogenide-based thermoelectrics

  14. Enhanced interfacial thermal transport in pnictogen tellurides metallized with a lead-free solder alloy

    Energy Technology Data Exchange (ETDEWEB)

    Devender,; Ramanath, Ganpati, E-mail: Ramanath@rpi.edu [Department of Materials Science and Engineering, Rensselaer Polytechnic Institute, Troy, New York 12180 (United States); Lofgreen, Kelly; Devasenathipathy, Shankar; Swan, Johanna; Mahajan, Ravi [Intel Corporation, Assembly Test and Technology Development, Chandler, Arizona 85226 (United States); Borca-Tasciuc, Theodorian [Department of Mechanical Aerospace and Nuclear Engineering, Rensselaer Polytechnic Institute, Troy, New York 12180 (United States)

    2015-11-15

    Controlling thermal transport across metal–thermoelectric interfaces is essential for realizing high efficiency solid-state refrigeration and waste-heat harvesting power generation devices. Here, the authors report that pnictogen chalcogenides metallized with bilayers of Sn{sub 96.5}Ag{sub 3}Cu{sub 0.5} solder and Ni barrier exhibit tenfold higher interfacial thermal conductance Γ{sub c} than that obtained with In/Ni bilayer metallization. X-ray diffraction and x-ray spectroscopy indicate that reduced interdiffusion and diminution of interfacial SnTe formation due to Ni layer correlates with the higher Γ{sub c}. Finite element modeling of thermoelectric coolers metallized with Sn{sub 96.5}Ag{sub 3}Cu{sub 0.5}/Ni bilayers presages a temperature drop ΔT ∼ 22 K that is 40% higher than that obtained with In/Ni metallization. Our results underscore the importance of controlling chemical intermixing at solder–metal–thermoelectric interfaces to increase the effective figure of merit, and hence, the thermoelectric cooling efficiency. These findings should facilitate the design and development of lead-free metallization for pnictogen chalcogenide-based thermoelectrics.

  15. Design of Experiments to Determine Causes of Flex Cable Solder Wicking, Discoloration and Hole Location Defects

    Energy Technology Data Exchange (ETDEWEB)

    Wolfe, Larry

    2009-04-22

    Design of Experiments (DoE) were developed and performed in an effort to discover and resolve the causes of three different manufacturing issues; large panel voids after Hot Air Solder Leveling (HASL), cable hole locations out of tolerance after lamination and delamination/solder wicking around flat flex cable circuit lands after HASL. Results from a first DoE indicated large panel voids could be eliminated by removing the pre-HASL cleaning. It also revealed eliminating the pre-HASL bake would not be detrimental when using a hard press pad lamination stackup. A second DoE indicated a reduction in hard press pad stackup lamination pressure reduced panel stretch in the y axis approximately 70%. A third DoE illustrated increasing the pre-HASL bake temperature could reduce delamination/solder wicking when using a soft press pad lamination stackup.

  16. Dissolution ad uptake of cadmium from dental gold solder alloy implants

    International Nuclear Information System (INIS)

    Pure metallic cadmium was irradiated by means of thermal neutrons. The irradiated cadmium (115Cd) was placed in bags of gold foil and the bags were implanted subcutaneously in the neck region of mice. Two and 3 d respectively after implantation the mice were killed, the bags removed and the animals subjected to whole-body autoradiography. The autoradiograms revealed an uptake of 115Cd in liver and kidney. In another experiment specimens of a cadmium-containing dental gold solder alloy, a cadmium-free dental casting gold alloy and soldered assemblies made of these two alloys were implanted subcutaneously in the neck region of mice. The animals were killed after 6 months; cadmium analysis showed significant increases in the cadmium concentration in liver and kidney of those mice which had been given implants of gold solder alloy. The study clearly shows that due to electrochemical corrosion cadmium can be released from implants and accumulated in the kidneys and the liver. (author)

  17. Instantaneous fluxless bonding of Au with Pb-Sn solder in ambient atmosphere

    Science.gov (United States)

    Lee, Teck Kheng; Zhang, Sam; Wong, Chee Cheong; Tan, Ah Chin

    2005-08-01

    A fluxless bonding technique has been developed as a method of flip-chip bonding for microelectronic packaging. The fluxless bonding technique can be achieved instantaneously in an ambient environment between metallic stud bumps and predefined molten solder. This paper describes the mechanics of the bonding action and verifies the effectiveness of this bonding method through wetting balance tests and scanning electron microscope and energy dispersive x-ray analysis. This technique has been demonstrated by using a gold stud bump to break the tin oxide layer over molten solder. This allows for a fast, solid liquid interdiffusion between gold (Au) and the fresh molten eutectic lead-tin (Pb-Sn) solder for joint formation during solidification. This bonding method has been successfully tested with 130-μm-pitch flip-chip bond pads on a joint-in-via flex substrate architecture.

  18. Interfacial Reactions Between In-Sn Solder and Ni-Fe Platings

    Science.gov (United States)

    Daghfal, John P.; Shang, P. J.; Liu, Z. Q.; Shang, J. K.

    2009-12-01

    Interfacial interactions in a Ni- xFe-Sn-In eutectic solder ( x = 30 at.%, 55 at.%) have been examined. Transmission and scanning electron microscopy (TEM/SEM) were utilized to investigate the structure, composition, and morphology of the intermetallic compounds (IMCs). Upon reflow, Ni3Sn4 and FeSn2 phases appeared at the interface along with Cu6Sn5 in the solder. Annealing experiments revealed the formation of a bilayer IMC that was Fe-rich adjacent to the Ni-Fe metallization and Ni-rich on the solder side. Kinetic studies established the apparent activation energies for both systems to be 51.8 kJ/mol and 85.1 kJ/mol, for 30 at.% and 55 at.% Fe contents, respectively. In the Fe-rich system, globular Ni3Sn4 crystals were formed upon reflow, but were changed into a cubic/faceted structure after annealing.

  19. NASA-DoD Lower Process Temperature Lead-Free Solder Project Overview

    Science.gov (United States)

    Kessel, Kurt R.

    2014-01-01

    This project is a follow-on effort to the Joint Council on Aging AircraftJoint Group on Pollution Prevention (JCAAJG-PP) Pb-free Solder Project and NASA-DoD Lead-Free Electronics Project which were the first projects to test the reliability of Pb-free solder joints against the requirements of the aerospace and military community. This effort would continue to build on the results from the JCAAJG-PP Lead-Free Solder Project and NASA-DoD Lead-Free Electronics Project while focusing on a particular failure mechanism currently plaguing Pb-free assemblies, pad cratering.The NASA-DoD Lead-Free Electronics Project confirmed that pad cratering is one of the dominant failure modes that occur in various board level reliability tests, especially under dynamic loading. Pad Cratering is a latent defect that may occur during assembly, rework, and post assembly handling and testing.

  20. Nanoscale Soldering of Positioned Carbon Nanotubes using Highly Conductive Electron Beam Induced Gold Deposition

    DEFF Research Database (Denmark)

    Madsen, Dorte Nørgaard; Mølhave, Kristian; Mateiu, Ramona Valentina; Bøggild, Peter; Rasmussen, A.M.; Appel, C.C.; Brorson, M; Jacobsen, C.J.H.

    2003-01-01

    We have developed an in-situ method for controlled positioning of carbon nanotubes followed by highly conductive contacting of the nanotubes, using electron beam assisted deposition of gold. The positioning and soldering process takes place inside an Environmental Scanning Electron Microscope (E...... embedded in a carbon matrix. Nanoscale soldering of multi-walled carbon nanotubes (MWNT) onto microelectrodes was achieved by deposition of a conducting gold line across a contact point between nanotube and electrode. The solderings were found to be mechanically stronger than the carbon nanotubes. We have......-SEM) in the presence of a source of gold-organic precursor gas. Bridges deposited between suspended microelectrodes show resistivities down to 10-4 Ωcm and Transmission Electron Microscopy (TEM) of the deposits reveals a dense core of gold particles surrounded by a crust of small gold nanoparticles...

  1. High-yield production of a stable Vero cell-based vaccine candidate against the highly pathogenic avian influenza virus H5N1

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Fangye; Zhou, Jian; Ma, Lei; Song, Shaohui; Zhang, Xinwen; Li, Weidong; Jiang, Shude [No. 5, Department of Bioproducts, Institute of Medical Biology, Chinese Academy of Medical Science and Pecking Union Medical College, Jiaoling Avenue 935, Kunming, Yunnan Province 650102, People' s Republic of China (China); Wang, Yue, E-mail: euy-tokyo@umin.ac.jp [National Institute for Viral Disease Control and Prevention, China Center for Disease Control and Prevention, Yingxin Lane 100, Xicheng District, Beijing 100052, People' s Republic of China (China); Liao, Guoyang, E-mail: liaogy@21cn.com [No. 5, Department of Bioproducts, Institute of Medical Biology, Chinese Academy of Medical Science and Pecking Union Medical College, Jiaoling Avenue 935, Kunming, Yunnan Province 650102, People' s Republic of China (China)

    2012-05-18

    Highlights: Black-Right-Pointing-Pointer Vero cell-based HPAI H5N1 vaccine with stable high yield. Black-Right-Pointing-Pointer Stable high yield derived from the YNVa H3N2 backbone. Black-Right-Pointing-Pointer H5N1/YNVa has a similar safety and immunogenicity to H5N1delta. -- Abstract: Highly pathogenic avian influenza (HPAI) viruses pose a global pandemic threat, for which rapid large-scale vaccine production technology is critical for prevention and control. Because chickens are highly susceptible to HPAI viruses, the supply of chicken embryos for vaccine production might be depleted during a virus outbreak. Therefore, developing HPAI virus vaccines using other technologies is critical. Meeting vaccine demand using the Vero cell-based fermentation process has been hindered by low stability and yield. In this study, a Vero cell-based HPAI H5N1 vaccine candidate (H5N1/YNVa) with stable high yield was achieved by reassortment of the Vero-adapted (Va) high growth A/Yunnan/1/2005(H3N2) (YNVa) virus with the A/Anhui/1/2005(H5N1) attenuated influenza vaccine strain (H5N1delta) using the 6/2 method. The reassorted H5N1/YNVa vaccine maintained a high hemagglutination (HA) titer of 1024. Furthermore, H5N1/YNVa displayed low pathogenicity and uniform immunogenicity compared to that of the parent virus.

  2. High-yield production of a stable Vero cell-based vaccine candidate against the highly pathogenic avian influenza virus H5N1

    International Nuclear Information System (INIS)

    Highlights: ► Vero cell-based HPAI H5N1 vaccine with stable high yield. ► Stable high yield derived from the YNVa H3N2 backbone. ► H5N1/YNVa has a similar safety and immunogenicity to H5N1delta. -- Abstract: Highly pathogenic avian influenza (HPAI) viruses pose a global pandemic threat, for which rapid large-scale vaccine production technology is critical for prevention and control. Because chickens are highly susceptible to HPAI viruses, the supply of chicken embryos for vaccine production might be depleted during a virus outbreak. Therefore, developing HPAI virus vaccines using other technologies is critical. Meeting vaccine demand using the Vero cell-based fermentation process has been hindered by low stability and yield. In this study, a Vero cell-based HPAI H5N1 vaccine candidate (H5N1/YNVa) with stable high yield was achieved by reassortment of the Vero-adapted (Va) high growth A/Yunnan/1/2005(H3N2) (YNVa) virus with the A/Anhui/1/2005(H5N1) attenuated influenza vaccine strain (H5N1delta) using the 6/2 method. The reassorted H5N1/YNVa vaccine maintained a high hemagglutination (HA) titer of 1024. Furthermore, H5N1/YNVa displayed low pathogenicity and uniform immunogenicity compared to that of the parent virus.

  3. Investigation Of The Effects Of Reflow Profile Parameters On Lead-free Solder Bump Volumes And Joint Integrity

    Science.gov (United States)

    Amalu, E. H.; Lui, Y. T.; Ekere, N. N.; Bhatti, R. S.; Takyi, G.

    2011-01-01

    The electronics manufacturing industry was quick to adopt and use the Surface Mount Technology (SMT) assembly technique on realization of its huge potentials in achieving smaller, lighter and low cost product implementations. Increasing global customer demand for miniaturized electronic products is a key driver in the design, development and wide application of high-density area array package format. Electronic components and their associated solder joints have reduced in size as the miniaturization trend in packaging continues to be challenged by printing through very small stencil apertures required for fine pitch flip-chip applications. At very narrow aperture sizes, solder paste rheology becomes crucial for consistent paste withdrawal. The deposition of consistent volume of solder from pad-to-pad is fundamental to minimizing surface mount assembly defects. This study investigates the relationship between volume of solder paste deposit (VSPD) and the volume of solder bump formed (VSBF) after reflow, and the effect of reflow profile parameters on lead-free solder bump formation and the associated solder joint integrity. The study uses a fractional factorial design (FFD) of 24-1 Ramp-Soak-Spike reflow profile, with all main effects and two-way interactions estimable to determine the optimal factorial combination. The results from the study show that the percentage change in the VSPD depends on the combination of the process parameters and reliability issues could become critical as the size of solder joints soldered on the same board assembly vary greatly. Mathematical models describe the relationships among VSPD, VSBF and theoretical volume of solder paste. Some factors have main effects across the volumes and a number of interactions exist among them. These results would be useful for R&D personnel in designing and implementing newer applications with finer-pitch interconnect.

  4. Tin whisker growth from micro-alloyed SAC solders in corrosive climate

    Energy Technology Data Exchange (ETDEWEB)

    Illés, Balázs, E-mail: billes@ett.bme.hu [Department of Electronics Technology, Budapest University of Technology and Economics, Egry József St. 18, Budapest 1111 (Hungary); Horváth, Barbara [National Institute for Materials Science, 1-2-1 Sengen, Tsukuba 305-0047 (Japan)

    2014-12-15

    Highlights: • Lead-free micro-alloyed SAC solders can also develop tin whiskers. • The whiskering ability depends on the corrosion behavior of the SAC solders. • Copper and bismuth traces were found within the whiskers. • Copper and bismuth atoms can fragment the whisker grain. • The grain fragmentation can reduce the maximum length of the developed whiskers. - Abstract: In this paper the tin whisker growth properties of lead-free SAC (SnAgCu) solder alloys were investigated. There different alloys were studied: two micro-alloyed SAC (SnAgCu + Bi + Sb) and the widely applied SAC305 as reference. FR4 test board was developed for 0805 chip resistor components. Solder joints were fabricated on imm-Sn surface finish. The samples were aged in elevated temperature and different humidity levels to induce the tin whisker formation: at 85 °C/85RH% and 85 °C/20RH%. The test duration was 3000 h. Whisker growth was checked after every 500 h by scanning electron microscope. The developed whiskers were etched by focused ion beam and the cross-sections were observed by scanning ion microscope and transmission electron microscope. It was shown that the lead-free SAC solder alloys can also develop tin whiskers and the whiskering ability depends on the corrosion behavior of the SAC solders. Copper and bismuth precipitations were found at the whisker roots and within the whiskers which could effect on the number, length and type of the developed whiskers.

  5. Tin whisker growth from micro-alloyed SAC solders in corrosive climate

    International Nuclear Information System (INIS)

    Highlights: • Lead-free micro-alloyed SAC solders can also develop tin whiskers. • The whiskering ability depends on the corrosion behavior of the SAC solders. • Copper and bismuth traces were found within the whiskers. • Copper and bismuth atoms can fragment the whisker grain. • The grain fragmentation can reduce the maximum length of the developed whiskers. - Abstract: In this paper the tin whisker growth properties of lead-free SAC (SnAgCu) solder alloys were investigated. There different alloys were studied: two micro-alloyed SAC (SnAgCu + Bi + Sb) and the widely applied SAC305 as reference. FR4 test board was developed for 0805 chip resistor components. Solder joints were fabricated on imm-Sn surface finish. The samples were aged in elevated temperature and different humidity levels to induce the tin whisker formation: at 85 °C/85RH% and 85 °C/20RH%. The test duration was 3000 h. Whisker growth was checked after every 500 h by scanning electron microscope. The developed whiskers were etched by focused ion beam and the cross-sections were observed by scanning ion microscope and transmission electron microscope. It was shown that the lead-free SAC solder alloys can also develop tin whiskers and the whiskering ability depends on the corrosion behavior of the SAC solders. Copper and bismuth precipitations were found at the whisker roots and within the whiskers which could effect on the number, length and type of the developed whiskers

  6. Comparative testing of six antigen-based malaria vaccine candidates directed toward merozoite-stage Plasmodium falciparum

    DEFF Research Database (Denmark)

    Arnot, David E; Cavanagh, David R; Remarque, Edmond J;

    2008-01-01

    Immunogenicity testing of Plasmodium falciparum antigens being considered as malaria vaccine candidates was undertaken in rabbits. The antigens compared were recombinant baculovirus MSP-1(19) and five Pichia pastoris candidates, including two versions of MSP-1(19), AMA-1 (domains I and II), AMA-1...

  7. INFLUENCE OF LAP-SOLDERED JOINT GEOMETRICAL DIMENSIONS ON ITS STRESS DEFORMED STATE

    Directory of Open Access Journals (Sweden)

    V. K. Sheleg

    2015-01-01

    Full Text Available The paper presents results of the analysis pertaining to lap-soldered joint bearing capacity of parts having various length and thickness. It has been shown that difference in dimensions of connected parts makes a pronounced effect on stress deformed state of lap-soldered joints. It has been determined that there is an increase in working stresses along the edges of a lap in parts with larger length and smaller thickness that is caused by action of a bending moment.

  8. Observation of amorphous chromium in modified C4 flip chip solder joints after thermal stress testing

    International Nuclear Information System (INIS)

    Flip chip reliability was evaluated using thermal stress tests at 150 deg. C. Electrical failures of flip chip devices were found to occur at the solder/under-bump-metallization interface by forming a porous amorphous chromium layer. The formation of the porous amorphous layer responsible for electrical failures resulted from the outdiffusion of copper atoms from a copper-chromium co-deposit, used as one of the under-bump-metallization layers. A strong interaction of Cu with the Sn component of the solder is the driving force of the Cu outdiffusion

  9. The Numerical Analysis of Strain Behavior at Solder Joint and Interface of Flip Chip Package

    Institute of Scientific and Technical Information of China (English)

    S; C; Chen; Y; C; Lin

    2002-01-01

    The flip chip package is a kind of advanced electri ca l packages. Due to the requirement of miniaturization, lower weight, higher dens ity and higher performance in the advanced electric package, it is expected that flip chip package will soon be a mainstream technology. The silicon chip is dir ectly connected to printing circuit substrate by SnPb solder joints. Also, the u nderfill, a composite of polymer and silica particles, is filled in the gap betw een the chip and substrate around the solder joint...

  10. A novel technique and soldering method to improve performance of transparent polymer antennas

    OpenAIRE

    Peter, T; Nilavalan, R; AbuTarboush, HF; Cheung, SW

    2010-01-01

    A novel technique and a nonthermal soldering method to improve the performance of AgHT-8 transparent polymer antennas are proposed in this letter. The proposed technique involves the removal of the coating layer at areas on the coplanar waveguide (CPW) ground and feed line where the connectors of the coaxial feed or legs of the SMA connectors will be attached and applying a coat of silver paint on the exposed areas before cold-soldering the coaxial connections or SMA connector legs. The nonth...

  11. Development of high melting point, environmentally friendly solders, using the calphad approach

    DEFF Research Database (Denmark)

    Chidambaram, Vivek; Hald, John; Hattel, Jesper Henri

    2008-01-01

    An attempt has been made using the CALPHAD approach via Thermo-Calc to explore the various possible chemical compositions that adhere to the melting criterion i.e. 270-350 degrees C, required to replace the traditionally used high lead content solders for first level packaging applications. Various...... tension have also been considered. Special focus has been given to toxicity related issues since the main ideology of looking for an alternative to high lead containing solders is not related to technical issues but due to environmental concerns....

  12. Suppressing tin whisker growth in lead-free solders and platings

    Science.gov (United States)

    Hoffman, Elizabeth N; Lam, Poh-Sang

    2014-04-29

    A process of irradiation Sn containing Pb-free solder to mitigate whisker formation and growth thereon is provided. The use of gamma radiation such as cobalt-60 has been applied to a substrate of Sn on copper has been found to change the morphology of the crystalline whisker growth to a more truncated hillock pattern. The change in morphology greatly reduces the tendency of whiskers to contribute to electrical short-circuits being used as a Pb-free solder system on a copper substrate.

  13. Mechanical performances of lead-free solder joint connections with applications in the aerospace domain

    Directory of Open Access Journals (Sweden)

    Georgiana PADURARU

    2016-03-01

    Full Text Available The paper presents some theoretical and experimental aspects regarding the tribological performances of lead-free solder joint connections, with application in the aerospace domain. In order to highlight the mechanical and tribological properties of solder joint in correlation with different pad finishes, there were made some mechanical determinations using a dedicated Share Test System. The theoretical model highlights the link between the experimental results and the influence of gravitational acceleration on the mechanical and functional integrity of the electronic assemblies that works in vibration environment. The paper novelty is provided by the interdisciplinary experiment that offers results that can be used in the mechanical, tribological, electronical and aerospace domains.

  14. MHD wave generators with a screw flow-through channel for automated soldering of the printed-circuit assemblies of radioelectronic apparatus

    Energy Technology Data Exchange (ETDEWEB)

    Gel' fgat, Y.M.; Simsons, Y.A.

    1985-04-01

    The basic characteristics of MHDW for soldering with a continuous wave of solder are presented. A similar presentation of characteristics describe soldering with two jets of solder. A diagram of an MHDW with a screw flow-through channel for creating a single continuous wave of solder is illustrated, and consists of a vat with the melted metal. The vat's bottom is constructed in the form of a circular cylinder placed in the hollow of a three-phase rotating-magnetic-field inductor. The main designs of MHD wave generators have proved to be very efficient for mass and large series production.

  15. High duty cycle hard soldered kilowatt laser diode arrays

    Science.gov (United States)

    Klumel, Genady; Karni, Yoram; Oppenheim, Jacob; Berk, Yuri; Shamay, Moshe; Tessler, Renana; Cohen, Shalom

    2010-02-01

    High-brightness laser diode arrays operating at a duty cycle of 10% - 20% are in ever-increasing demand for the optical pumping of solid state lasers and directed energy applications. Under high duty-cycle operation at 10% - 20%, passive (conductive) cooling is of limited use, while micro-coolers using de-ionized cooling water can considerably degrade device reliability. When designing and developing actively-cooled collimated laser diode arrays for high duty cycle operation, three main problems should be carefully addressed: an effective local and total heat removal, a minimization of packaging-induced and operational stresses, and high-precision fast axis collimation. In this paper, we present a novel laser diode array incorporating a built-in tap water cooling system, all-hard-solder bonded assembly, facet-passivated high-power 940 nm laser bars and tight fast axis collimation. By employing an appropriate layout of water cooling channels, careful choice of packaging materials, proper design of critical parts, and active optics alignment, we have demonstrated actively-cooled collimated laser diode arrays with extended lifetime and reliability, without compromising their efficiency, optical power density, brightness or compactness. Among the key performance benchmarks achieved are: 150 W/bar optical peak power at 10% duty cycle, >50% wallplug efficiency and 0.5 Ghots with thermal cycling between -20°C and 40°C and mechanical shocks at 500g acceleration. The results of both performance and reliability testing bear out the effectiveness and robustness of the manufacturing technology for high duty-cycle laser arrays.

  16. Do People 'Like' Candidates on Facebook?

    DEFF Research Database (Denmark)

    Nielsen, Rasmus Kleis

    The online popularity of a few exceptional candidates has led many to suggest that social media have given politicians powerful ways of communicating directly with voters. In this paper, we examine whether this is happening on a significant scale and show, based on analysis of 224 candidates invo...

  17. Effect of Electromigration on the Type of Drop Failure of Sn-3.0Ag-0.5Cu Solder Joints in PBGA Packages

    Science.gov (United States)

    Huang, M. L.; Zhao, N.

    2015-10-01

    Board-level drop tests of plastic ball grid array (PBGA) packages were performed in accordance with the Joint Electron Devices Engineering Council standard to investigate the effect of electromigration (EM) on the drop reliability of Sn-3.0Ag-0.5Cu solder joints with two substrate surface finishes, organic solderability preservative (OSP) and electroless nickel electroless palladium immersion gold (ENEPIG). In the as-soldered state, drop failures occurred at the substrate sides only, with cracks propagating within the interfacial intermetallic compound (IMC) layer for OSP solder joints and along the IMC/Ni-P interface for ENEPIG solder joints. The drop lifetime of OSP solder joints was approximately twice that of ENEPIG joints. EM had an important effect on crack formation and drop lifetime of the PBGA solder joints. ENEPIG solder joints performed better in drop reliability tests after EM, that is, the drop lifetime of ENEPIG joints decreased by 43% whereas that of OSP solder joints decreased by 91%, compared with the as-soldered cases. The more serious polarity effect, i.e., excessive growth of the interfacial IMC at the anode, was responsible for the sharper decrease in drop lifetime. The different types of drop failure of PBGA solder joints before and after EM, including the position of initiation and the propagation path of cracks, are discussed on the basis of the growth behavior of interfacial IMC.

  18. Evolution of intermetallic compounds layers in the soldered Sn-3.7Ag-1.0In-0.9Zn/Cu interface

    Energy Technology Data Exchange (ETDEWEB)

    Xu, R.L. [College of Materials Science and Engineering, Tianjin Key Laboratory of Advanced Jointing Technology, Tianjin University, Tianjin 30007 (China); Liu, Y.C. [College of Materials Science and Engineering, Tianjin Key Laboratory of Advanced Jointing Technology, Tianjin University, Tianjin 30007 (China)], E-mail: licmtju@163.com; Wei, C.; Wang, X.; Gao, Z.M. [College of Materials Science and Engineering, Tianjin Key Laboratory of Advanced Jointing Technology, Tianjin University, Tianjin 30007 (China)

    2009-01-22

    The formation and evolution of intermetallic compounds (IMCs) layer between the Sn-3.7Ag-1.0In-0.9Zn lead-free solder and Cu substrate were investigated for different soldering periods. The structure of the IMCs layer in the soldered interface varies apparently with increasing the soldering time. The interface soldered for 1 min is composed of a thick Cu{sub 5}Zn{sub 8} layer and a thin Cu{sub 6}Sn{sub 5} IMCs layer, which are separated by an intermediate solder layer. When the soldering time reaches 3 min, both the Cu{sub 5}Zn{sub 8} and Cu{sub 6}Sn{sub 5} layers grow thicker towards the middle solder layer, with the Cu{sub 5}Zn{sub 8} layer much thicker than the Cu{sub 6}Sn{sub 5} one. Later the Cu{sub 5}Zn{sub 8} layer will decomposed completely and the Cu{sub 6}Sn{sub 5} layer will grow prominently when the soldering time reaches 4 min. The evolution of the soldered interfacial structure was discussed in view of the governing factor for the atomic diffusion through the intermediate solder layer.

  19. Evolution of intermetallic compounds layers in the soldered Sn-3.7Ag-1.0In-0.9Zn/Cu interface

    International Nuclear Information System (INIS)

    The formation and evolution of intermetallic compounds (IMCs) layer between the Sn-3.7Ag-1.0In-0.9Zn lead-free solder and Cu substrate were investigated for different soldering periods. The structure of the IMCs layer in the soldered interface varies apparently with increasing the soldering time. The interface soldered for 1 min is composed of a thick Cu5Zn8 layer and a thin Cu6Sn5 IMCs layer, which are separated by an intermediate solder layer. When the soldering time reaches 3 min, both the Cu5Zn8 and Cu6Sn5 layers grow thicker towards the middle solder layer, with the Cu5Zn8 layer much thicker than the Cu6Sn5 one. Later the Cu5Zn8 layer will decomposed completely and the Cu6Sn5 layer will grow prominently when the soldering time reaches 4 min. The evolution of the soldered interfacial structure was discussed in view of the governing factor for the atomic diffusion through the intermediate solder layer

  20. Effect on properties of 42Sn58Bi solder joint by adding the 96.5Sn3.5Ag

    Science.gov (United States)

    Tang, Qinghua; Pan, Xiaoguang; Wu, C. M. L.; Chan, Y. C.

    2000-05-01

    The different composition in 42Sn58Bi and 96.5Sn3.5Ag system has been studied. The reflow conditions of various composition pastes were studied, and a suitable adding of Sn-Ag paste could raise the soldering temperature of paste. It was found that the shear tensile strength of solder joint could be improved after adding suitable Sn-Ag to Sn-Bi paste by testing the solder joint tension. The thermal fatigue properties were studied through performed thermal annealing and thermal shocking. The shear tensile strength of solder joints for adding suitable Sn-Ag is higher than the pure Sn- Bi after thermal shocking. The solder property, mechanical and fatigue failure properties of solder joint for adding suitable Sn-Ag could be improved. It was found that suitable Sn-Ag could decrease the porosity in Sn-Bi solder joint thought X-ray and SEM analysis.

  1. Influence of nanoparticle addition on the formation and growth of intermetallic compounds (IMCs) in Cu/Sn-Ag-Cu/Cu solder joint during different thermal conditions

    Science.gov (United States)

    Tan, Ai Ting; Tan, Ai Wen; Yusof, Farazila

    2015-06-01

    Nanocomposite lead-free solders are gaining prominence as replacements for conventional lead-free solders such as Sn-Ag-Cu solder in the electronic packaging industry. They are fabricated by adding nanoparticles such as metallic and ceramic particles into conventional lead-free solder. It is reported that the addition of such nanoparticles could strengthen the solder matrix, refine the intermetallic compounds (IMCs) formed and suppress the growth of IMCs when the joint is subjected to different thermal conditions such as thermal aging and thermal cycling. In this paper, we first review the fundamental studies on the formation and growth of IMCs in lead-free solder joints. Subsequently, we discuss the effect of the addition of nanoparticles on IMC formation and their growth under several thermal conditions. Finally, an outlook on the future growth of research in the fabrication of nanocomposite solder is provided.

  2. Intermetallic compound formation in Sn-Co-Cu, Sn-Ag-Cu and eutectic Sn-Cu solder joints on electroless Ni(P) immersion Au surface finish after reflow soldering

    International Nuclear Information System (INIS)

    The interfacial reactions between Sn-0.4Co-0.7Cu eutectic alloy and immersion Au/electroless Ni(P)/Cu substrate were investigated after reflow soldering at 260 deg. C for 2 min. Common Sn-4.0Ag-0.5Cu and eutectic Sn-0.7Cu solders were used as reference. Two types of intermetallic compounds (IMC) were found in the solder matrix of the Sn-0.4Co-0.7Cu alloy, namely coarser CoSn2 and finer Cu6Sn5 particles, while only one ternary (Cu, Ni)6Sn5 interfacial compound was detected between the solder alloy and the electroless nickel and immersion gold (ENIG) coated substrate. The same trend was also observed for the Sn-Ag-Cu and Sn-Cu solder joints. Compared with the CoSn2 particles found in the Sn-Co-Cu solder and the Ag3Sn particles found in the Sn-Ag-Cu solder, the Cu6Sn5 particles found in both solder systems exhibited finer structure and more uniform distribution. It was noted that the thickness of the interfacial IMCs for the Sn-Co-Cu, Sn-Ag-Cu and Sn-Cu alloys was 3.5 μm, 4.3 μm and 4.1 μm, respectively, as a result of longer reflow time above the alloy's melting temperature since the Sn-Ag-Cu solder alloy has the lowest melting point

  3. Intermetallic compound formation in Sn-Co-Cu, Sn-Ag-Cu and eutectic Sn-Cu solder joints on electroless Ni(P) immersion Au surface finish after reflow soldering

    Energy Technology Data Exchange (ETDEWEB)

    Sun Peng [Key State Lab for New Displays and System Integration (Chinese Ministry of Education), SMIT Center, Shanghai University, 200072 Shanghai (China) and Department of Microtechnology and Nanoscience, SMIT Center, Chalmers University of Technology, 412-96 Goeteborg (Sweden)]. E-mail: peng.sun@mc2.chalmers.se; Andersson, Cristina [Department of Microtechnology and Nanoscience, SMIT Center, Chalmers University of Technology, 412-96 Goeteborg (Sweden); Wei Xicheng [Key State Lab for New Displays and System Integration (Chinese Ministry of Education), SMIT Center, Shanghai University, 200072 Shanghai (China); Cheng Zhaonian [Department of Microtechnology and Nanoscience, SMIT Center, Chalmers University of Technology, 412-96 Goeteborg (Sweden); Shangguan Dongkai [Flextronics International, San Jose, CA (United States); Liu Johan [Key State Lab for New Displays and System Integration (Chinese Ministry of Education), SMIT Center, Shanghai University, 200072 Shanghai (China); Department of Microtechnology and Nanoscience, SMIT Center, Chalmers University of Technology, 412-96 Goeteborg (Sweden)

    2006-11-25

    The interfacial reactions between Sn-0.4Co-0.7Cu eutectic alloy and immersion Au/electroless Ni(P)/Cu substrate were investigated after reflow soldering at 260 deg. C for 2 min. Common Sn-4.0Ag-0.5Cu and eutectic Sn-0.7Cu solders were used as reference. Two types of intermetallic compounds (IMC) were found in the solder matrix of the Sn-0.4Co-0.7Cu alloy, namely coarser CoSn{sub 2} and finer Cu{sub 6}Sn{sub 5} particles, while only one ternary (Cu, Ni){sub 6}Sn{sub 5} interfacial compound was detected between the solder alloy and the electroless nickel and immersion gold (ENIG) coated substrate. The same trend was also observed for the Sn-Ag-Cu and Sn-Cu solder joints. Compared with the CoSn{sub 2} particles found in the Sn-Co-Cu solder and the Ag{sub 3}Sn particles found in the Sn-Ag-Cu solder, the Cu{sub 6}Sn{sub 5} particles found in both solder systems exhibited finer structure and more uniform distribution. It was noted that the thickness of the interfacial IMCs for the Sn-Co-Cu, Sn-Ag-Cu and Sn-Cu alloys was 3.5 {mu}m, 4.3 {mu}m and 4.1 {mu}m, respectively, as a result of longer reflow time above the alloy's melting temperature since the Sn-Ag-Cu solder alloy has the lowest melting point.

  4. Microstructural characterization and mechanical property of active soldering anodized 6061 Al alloy using Sn–3.5Ag–xTi active solders

    International Nuclear Information System (INIS)

    Active solders Sn–3.5Ag–xTi varied from x = 0 to 6 wt.% Ti addition were prepared by vacuum arc re-melting and the resultant phase formation and variation of microstructure with titanium concentration were analyzed using X-ray diffraction, optical microscopy and scanning electron microscopy. The Sn–3.5Ag–xTi active solders are used as metallic filler to join with anodized 6061 Al alloy for potential applications of providing a higher heat conduction path. Their joints and mechanical properties were characterized and evaluated in terms of titanium content. The mechanical property of joints was measured by shear testing. The joint strength was very dependent on the titanium content. Solder with a 0.5 wt.% Ti addition can successfully wet and bond to the anodized aluminum oxide layers of Al alloy and posses a shear strength of 16.28 ± 0.64 MPa. The maximum bonding strength reached 22.24 ± 0.70 MPa at a 3 wt.% Ti addition. Interfacial reaction phase and chemical composition were identified by a transmission electron microscope with energy dispersive spectrometer. Results showed that the Ti element reacts with anodized aluminum oxide to form Al3Ti-rich and Al3Ti phases at the joint interfaces. - Highlights: ► Active solder joining of anodized Al alloy needs 0.5 wt.% Ti addition for Sn–3.5Ag. ► The maximum bonding strength occurs at 3 wt.% Ti addition. ► The Ti reacts with anodized Al oxide to form Al3Ti-rich and Al3Ti at joint interface.

  5. Effects of bismuth on growth of intermetallic compounds in Sn-Ag-Cu Pb-free solder joints

    Institute of Scientific and Technical Information of China (English)

    LI Guo-yuan; SHI Xun-qing

    2006-01-01

    The effects of Bi addition on the growth of intermetallic compound (IMC) formation in Sn-3.8Ag-0.7Cu solder joints were investigated. The test samples were prepared by conventional surface mounting technology. To investigate the element diffusion and the growth kinetics of intermetallics formation in solder joint,isothermal aging test was performed at temperatures of 100,150,and 190 ℃,respectively. The optical microscope (OM) and scanning electron microscope (SEM) were used to observe microstructure evolution of solder joint and to estimate the thickness and the grain size of the intermetallic layers. The IMC phases were identified by energy dispersive X-ray (EDX) and X-ray diffractometer (XRD). The results clearly show that adding about 1.0% Bi in Sn-Ag-Cu solder alloy system can refine the grain size of the IMC and inhibit the excessive IMC growth in solder joints,and therefore improve the reliability of the Pb-free solder joints. Through observation of the microstructural evolution of the solder joints,the mechanism of inhibition of IMC growth due to Bi addition was proposed.

  6. Effect of Pd Thickness on the Interfacial Reaction and Shear Strength in Solder Joints Between Sn-3.0Ag-0.5Cu Solder and Electroless Nickel/Electroless Palladium/Immersion Gold (ENEPIG) Surface Finish

    Science.gov (United States)

    Kim, Young Min; Park, Jin-Young; Kim, Young-Ho

    2012-04-01

    Intermetallic compound formation at the interface between Sn-3.0Ag-0.5Cu (SAC) solders and electroless nickel/electroless palladium/immersion gold (ENEPIG) surface finish and the mechanical strength of the solder joints were investigated at various Pd thicknesses (0 μm to 0.5 μm). The solder joints were fabricated on the ENEPIG surface finish with SAC solder via reflow soldering under various conditions. The (Cu,Ni)6Sn5 phase formed at the SAC/ENEPIG interface after reflow in all samples. When samples were reflowed at 260°C for 5 s, only (Cu,Ni)6Sn5 was observed at the solder interfaces in samples with Pd thicknesses of 0.05 μm or less. However, the (Pd,Ni)Sn4 phase formed on (Cu,Ni)6Sn5 when the Pd thickness increased to 0.1 μm or greater. A thick and continuous (Pd,Ni)Sn4 layer formed over the (Cu,Ni)6Sn5 layer, especially when the Pd thickness was 0.3 μm or greater. High-speed ball shear test results showed that the interfacial strengths of the SAC/ENEPIG solder joints decreased under high strain rate due to weak interfacial fracture between (Pd,Ni)Sn4 and (Cu,Ni)6Sn5 interfaces when the Pd thickness was greater than 0.3 μm. In the samples reflowed at 260°C for 20 s, only (Cu,Ni)6Sn5 formed at the solder interfaces and the (Pd,Ni)Sn4 phase was not observed in the solder interfaces, regardless of Pd thickness. The shear strength of the SAC/ENIG solder joints was the lowest of the joints, and the mechanical strength of the SAC/ENEPIG solder joints was enhanced as the Pd thickness increased to 0.1 μm and maintained a nearly constant value when the Pd thickness was greater than 0.1 μm. No adverse effect on the shear strength values was observed due to the interfacial fracture between (Pd,Ni)Sn4 and (Cu,Ni)6Sn5 since the (Pd,Ni)Sn4 phase was already separated from the (Cu,Ni)6Sn5 interface. These results indicate that the interfacial microstructures and mechanical strength of solder joints strongly depend on the Pd thickness and reflow conditions.

  7. Usolka section (southern Urals, Russia: a potential candidate for GSSP to define the base of the Gzhelian Stage in the global chronostratigraphic scale

    Directory of Open Access Journals (Sweden)

    Valery V. Chernykh

    2006-12-01

    Full Text Available Conodont species Streptognathodus simulator Ellison, 1941 has been proposed recently to define the Kasimovian-Gzhelian boundary in the global chronostratigraphic scale.The species distributed globally and traditionally has been used as a marker of the base of the Gzhelian Stage in the type sections in Moscow Basin and Urals. Recent studies of conodont taxonomy and biostratigraphy in southern Urals have established the chronocline with ascendant and descendant to Streptognathodus simulator species. Usolka section proposed here as a potential candidate for the GSSP (Global Stratotype Section and Point to define the global Gzhelian Stage at the FAD of the Streptognathodus simulator within the chronocline Streptognathodus praenuntius Chernykh, 2005 – St. simulator Ellison, 1941 – St. auritus Chernykh, 2005. The chronocline recovered within 2.7 m of beds 4 and 5 at the Usolka section, with all three species described and properly figured. No obvious interruptions in sedimentation are recorded within the Kasimovian-Gzhelian transition there. Several volcanic ash beds are present below and above the proposed boundary, making radiometric calibration highly possible in the near future. Mode of preservation of conodonts with a CAI of around 1.0–1.5 provides excellent basis for the geochemical studies. Accessibility presently is adequate, and this exposure will be improved and maintained permanently for interested scientists. Future access will be guaranteed by means of legislative action to create a scientific preserve.

  8. ZDHHC8 as a candidate gene for schizophrenia: Analysis of a putative functional intronic marker in case-control and family-based association studies

    Directory of Open Access Journals (Sweden)

    Jabs Burkhard

    2005-10-01

    Full Text Available Abstract Background The chromosome 22q11 region is proposed as a major candidate locus for susceptibility genes to schizophrenia. Recently, the gene ZDHHC8 encoding a putative palmitoyltransferase at 22q11 was proposed to increase liability to schizophrenia based on both animal models and human association studies by significant over-transmission of allele rs175174A in female, but not male subjects with schizophrenia. Methods Given the genetic complexity of schizophrenia and the potential genetic heterogeneity in different populations, we examined rs175174 in 204 German proband-parent triads and in an independent case-control study (schizophrenic cases: n = 433; controls: n = 186. Results In the triads heterozygous parents transmitted allele G preferentially to females, and allele A to males (heterogeneity χ2 = 4.43; p = 0.035. The case-control sample provided no further evidence for overall or gender-specific effects regarding allele and genotype frequency distributions. Conclusion The findings on rs175174 at ZDHHC8 are still far from being conclusive, but evidence for sexual dimorphism is moderate, and our data do not support a significant genetic contribution of rs175174 to the aetiopathogenesis of schizophrenia.

  9. TAXONOMY AND BIOSTRATIGRAPHIC RECORD OF THE UPPER TRIASSIC CONODONTS OF THE PIZZO MONDELLO SECTION (WESTERN SICILY, ITALY, GSSP CANDIDATE FOR THE BASE OF THE NORIAN

    Directory of Open Access Journals (Sweden)

    MICHELE MAZZA

    2012-03-01

    Full Text Available New taxonomic and biostratigraphic investigations on the late Carnian to Rhaetian (Upper Triassic platform conodonts from the Pizzo Mondello section (Western Sicily, Italy, Sicano basin are here presented. Pizzo Mondello is one of the two GSSP candidates for the Carnian/Norian boundary; the section is a 430 m thick continuous succession of upper Carnian to upper Norian marine limestones (Scillato Formation, characterized by uniform facies and high sedimentation rates, and ca. 20 m of Rhaetian white calcilutites (Portella Gebbia limestone. Pizzo Mondello offers one of the most complete conodont records for this time interval in the Tethys. The conodont faunas are characterized by a large variety of species, belonging to the genera Carnepigondolella, Epigondolella, Metapolygnathus, Misikella, Mockina, Neocavitella, Norigondolella, Paragondolella, and Parvigondolella. The richness of the populations allowed a detailed revision and description of all the Upper Triassic species and morphotypes recovered. The revision of the problematic species Carnepigondolella nodosa and "Metapolygnathus communisti B" was thus possible, leading to the establishment of two new species: Carnepigondolella tuvalica n.sp. and Carnepigondolella gulloae n.sp. The latter species would be a good proxy for the Carnian/Norian boundary in the case that the FAD of Halobia austriaca (sample FNP135a will be selected as the primary biomarker for the base of the Norian. 

  10. Protection against multiple influenza A virus strains induced by candidate recombinant vaccine based on heterologous M2e peptides linked to flagellin.

    Directory of Open Access Journals (Sweden)

    Liudmila A Stepanova

    Full Text Available Matrix 2 protein ectodomain (M2e is considered a promising candidate for a broadly protective influenza vaccine. M2e-based vaccines against human influenza A provide only partial protection against avian influenza viruses because of differences in the M2e sequences. In this work, we evaluated the possibility of obtaining equal protection and immune response by using recombinant protein on the basis of flagellin as a carrier of the M2e peptides of human and avian influenza A viruses. Recombinant protein was generated by the fusion of two tandem copies of consensus M2e sequence from human influenza A and two copies of M2e from avian A/H5N1 viruses to flagellin (Flg-2M2eh2M2ek. Intranasal immunisation of Balb/c mice with recombinant protein significantly elicited anti-M2e IgG in serum, IgG and sIgA in BAL. Antibodies induced by the fusion protein Flg-2M2eh2M2ek bound efficiently to synthetic peptides corresponding to the human consensus M2e sequence as well as to the M2e sequence of A/Chicken/Kurgan/05/05 RG (H5N1 and recognised native M2e epitopes exposed on the surface of the MDCK cells infected with A/PR/8/34 (H1N1 and A/Chicken/Kurgan/05/05 RG (H5N1 to an equal degree. Immunisation led to both anti-M2e IgG1 and IgG2a response with IgG1 prevalence. We observed a significant intracellular production of IL-4, but not IFN-γ, by CD4+ T-cells in spleen of mice following immunisation with Flg-2M2eh2M2ek. Immunisation with the Flg-2M2eh2M2ek fusion protein provided similar protection from lethal challenge with human influenza A viruses (H1N1, H3N2 and avian influenza virus (H5N1. Immunised mice experienced significantly less weight loss and decreased lung viral titres compared to control mice. The data obtained show the potential for the development of an M2e-flagellin candidate influenza vaccine with broad spectrum protection against influenza A viruses of various origins.

  11. Laser balloon vascular welding using a dye-enhanced albumin solder

    Science.gov (United States)

    Ott, Beat; Zueger, Benno J.; Erni, Dominique; Banic, Andrej; Schaffner, Thomas; Weber, Heinz P.; Frenz, Martin

    2001-05-01

    Porcine posterior tibial arteries (n equals 50) and saphenous veins (n equals 32) have been welded end-to-end using an 808 nm diode laser combined with an indocyanine green enhanced albumin solder. For comparison, the same welding procedure has been performed with a Holmium:YAG laser without solder. Both lasers were running in continuous wave (cw) regime at a power limited below 1.2 W. The vascular stumps were approached to each other over a coronary dilatation catheter in order to obtain a precise alignment. The balloon catheter simplified vessel handling and the tight vessel positioning prevented a solder penetration into the lumen. Standard histology revealed for both welding techniques a lateral tissue damage between 2 and 3 mm. The vessels welded with the 808 nm diode laser using albumin solder showed considerably higher tensile strength (1 N compared to 0.3 N) than vessels welded exclusively by Ho:YAG laser radiation. In contrast, leaking pressure (350 +/- 200 mmHg) and bursting pressure 457 +/- 200 mmHg) were independent of the welding technique used.

  12. Reliability of Solder Materials (Sn-Pb and Pb-Free) for Deep Space Missions

    Science.gov (United States)

    Ramesham, Rajeshuni

    2011-01-01

    The purpose of this study is to assess the experimental reliability results of miniaturized passive components (01005, 0201, 0402, 0603, 0805, and 1206) assembled using surface mounting processes with tin-lead (Sn-Pb) and lead-free (Pb-Free) solder alloys under extreme temperature deep space environments.

  13. Microstructural Coarsening during Thermomechanical Fatigue and Annealing of Micro Flip-Chip Solder Joints

    Energy Technology Data Exchange (ETDEWEB)

    Barney, Monica M.

    1998-12-01

    Microstructural evolution due to thermal effects was studied in micro solder joints (55 {+-} 5 {micro}m). The composition of the Sn/Pb solder studied was found to be hypereutectic with a tin content of 65--70 wt%.This was determined by Energy Dispersive X-ray analysis and confirmed with quantitative stereology. The quantitative stereological value of the surface-to-volume ratio was used to characterize and compare the coarsening during thermal cycling from 0--160 C to the coarsening during annealing at 160 C. The initial coarsening of the annealed samples was more rapid than the cycled samples, but tapered off as time to the one-half as expected. Because the substrates to which the solder was bonded have different thermal expansion coefficients, the cycled samples experienced a mechanical strain with thermal cycling. The low-strain cycled samples had a 2.8% strain imposed on the solder and failed by 1,000 cycles, despite undergoing less coarsening than the annealed samples. The high-strain cycled samples experienced a 28% strain and failed between 25 and 250 cycles. No failures were observed in the annealed samples. Failure mechanisms and processing issues unique to small, fine pitch joints are also discussed.

  14. Contamination profile of Printed Circuit Board Assemblies in relation to soldering types and conformal coating

    DEFF Research Database (Denmark)

    Conseil, Helene; Jellesen, Morten Stendahl; Ambat, Rajan

    2014-01-01

    measuring the leak current using a twin platinum electrode setup. Localized extraction of residue was carried out using a commercial C3 extraction system. Results clearly show that the amount and distribution of flux residues are a function of the soldering process, and the level can be reduced by an...

  15. Nucleation and Growth of Tin in Pb-Free Solder Joints

    Science.gov (United States)

    Gourlay, C. M.; Belyakov, S. A.; Ma, Z. L.; Xian, J. W.

    2015-08-01

    The solidification of Pb-free solder joints is overviewed with a focus on the formation of the βSn grain structure and grain orientations. Three solders commonly used in electronics manufacturing, Sn-3Ag-0.5Cu, Sn-3.5Ag, and Sn-0.7Cu-0.05Ni, are used as case studies to demonstrate that (I) growth competition between primary dendrites and eutectic fronts during growth in undercooled melts is important in Pb-free solders and (II) a metastable eutectic containing NiSn4 forms in Sn-3.5Ag/Ni joints. Additionally, it is shown that the substrate (metallization) has a strong influence on the nucleation and growth of tin. We identify Co, Pd, and Pt substrates as having the potential to control solidification and microstructure formation. In the case of Pd and Pt substrates, βSn is shown to nucleate on the PtSn4 or PdSn4 intermetallic compound (IMC) reaction layer at relatively low undercooling of ~4 K, even for small solder ball diameters down to <200 μm.

  16. Au-SN Flip-Chip Solder Bump for Microelectronic and Optoelectronic Applications

    CERN Document Server

    Yoon, Jeong-Won; Koo, Ja-Myeong; Jung, Seung-Boo

    2007-01-01

    As an alternative to the time-consuming solder pre-forms and pastes currently used, a co-electroplating method of eutectic Au-Sn alloy was used in this study. Using a co-electroplating process, it was possible to plate the Au-Sn solder directly onto a wafer at or near the eutectic composition from a single solution. Two distinct phases, Au5Sn and AuSn, were deposited at a composition of 30at.%Sn. The Au-Sn flip-chip joints were formed at 300 and 400 degrees without using any flux. In the case where the samples were reflowed at 300 degrees, only an (Au,Ni)3Sn2 IMC layer formed at the interface between the Au-Sn solder and Ni UBM. On the other hand, two IMC layers, (Au,Ni)3Sn2 and (Au,Ni)3Sn, were found at the interfaces of the samples reflowed at 400 degrees. As the reflow time increased, the thickness of the (Au,Ni)3Sn2 and (Au,Ni)3Sn IMC layers formed at the interface increased and the eutectic lamellae in the bulk solder coarsened.

  17. The thermodynamic database COST MP0602 for materials for high-temperature lead-free soldering

    Czech Academy of Sciences Publication Activity Database

    Kroupa, Aleš; Dinsdale, A.; Watson, A.; Vřešťál, J.; Zemanová, Adéla; Brož, P.

    2012-01-01

    Roč. 48, č. 3 (2012), s. 339-346. ISSN 1450-5339 R&D Projects: GA MŠk LD11024 Institutional support: RVO:68081723 Keywords : CALPHAD method * lead-free solders * thermodynamic database Subject RIV: BJ - Thermodynamics Impact factor: 1.435, year: 2012

  18. The COST MP0602 Thermodynamic Database for High-Temperature Lead-free Solders

    Czech Academy of Sciences Publication Activity Database

    Kroupa, Aleš; Dinsdale, A.; Watson, A.; Vřešťál, J.; Zemanová, Adéla; Brož, P.

    Rio de Janeiro, 2011. s. 104-104. [CALPHAD/40./. 22.05.2011-27.05.2011, Rio de Janeiro] R&D Projects: GA MŠk(CZ) OC08053 Institutional research plan: CEZ:AV0Z20410507 Keywords : COST MP0602 * lead-free solders Subject RIV: BJ - Thermodynamics

  19. Corrosion reliability of electronics: the influence of solder temperature on the decomposition of flux activators

    DEFF Research Database (Denmark)

    Piotrowska, Kamila; Conseil, Helene; Jellesen, Morten Stendahl;

    2014-01-01

    This manuscript gives a brief overview on the studies of thermal decomposition of solder flux systems commonly used in the electronic industry. Changes in chemical composition and structural changes of the flux components have been investigated as a function of temperature. Six weak organic acids...

  20. High-temperature creep and hardness of eutectic 80Au/20Sn solder

    International Nuclear Information System (INIS)

    Eutectic 80Au/20Sn solder is widely used for device packaging in optoelectronic and high power electronic industries. The knowledge of thermomechanical properties of the solder is critical for design and application. In this piece of work, Berkovich depth-sensing indentation test has been used to study the effect of temperature on the hardness and the creep behavior of the 80Au/20Sn solder alloy at temperatures ranging from 25 deg. C to 200 deg. C. The results showed that the hardness of eutectic 80Au/20Sn solder decreased as temperature increased. The change of hardness with temperature in the range from 25 deg. C to 150 deg. C could be considered as linear and a temperature coefficient of hardness of -1.1 x 10-2 GPa/deg. C could be estimated; thereafter the change of hardness tapers off as the temperature increases to 200 deg. C. On the other hand, the creep penetration and creep strain rate increased and its associated stress exponent decreased with temperature, which resulted in large plastic deformation during indentation

  1. The Development of the COST 531 Lead-Free Solders Thermodynamic Database

    Czech Academy of Sciences Publication Activity Database

    Kroupa, Aleš; Dinsdale, A.; Watson, A.; Vřešťál, J.; Vízdal, J.; Zemanová, Adéla

    2007-01-01

    Roč. 59, č. 7 (2007), s. 20-25. ISSN 1047-4838 R&D Projects: GA MŠk OC 531.002; GA AV ČR KJB200410601 Institutional research plan: CEZ:AV0Z20410507 Keywords : lead-free solders * thermodynamic database Subject RIV: BJ - Thermodynamic s Impact factor: 1.081, year: 2007

  2. Microstructure evolution in a Pb-free solder alloy during mechanical fatigue

    NARCIS (Netherlands)

    Matin, M. A.; Vellinga, W. P.; Geers, M. G. D.

    2006-01-01

    Microstructural evolution in a Sn-rich eutectic Sn-3.8Ag-0.7Cu solder alloy has been investigated in low cycle mechanical fatigue. Inhomogeneity in deformation occurred on a grain scale (determined by grain orientation and plastic anisotropy of Sn) and on a subgrain scale where persistent slip bands

  3. Laser-welded vs soldered nonprecious alloy dental bridges: a comparative study.

    Science.gov (United States)

    Apotheker, H; Nishimura, I; Seerattan, C

    1984-01-01

    The high cost of gold alloy has caused the dental profession to begin substituting nonprecious alloy for the framework in porcelain fused to metal bridges. Especially in long-span bridges it may be advantageous to make multiple castings and then join them for a better fit. As opposed to the highly successful soldering of gold, soldered nonprecious alloy bridges have a great failure rate in the mouth. Removal of and remaking of the bridges is thus the result. This study compares nonprecious units that have been laser-welded with those conventionally soldered. Seven identical bridges of three units were cast in a popular alloy composed of 74-78% nickel, 12-15% chromium, 4-6% molybdenum, and 1.8% maximum beryllium. One served as a control, while the remaining six were all cut in the same place. Of these, three were soldered with a gas oxygen torch. The other three were welded with a Nd-YAG laser. Better and stronger joints unlikely to fracture in the mouth were found with the laser-welded specimen. PMID:6147733

  4. Electron microscopy of nanoparticles for lead-free soldering prepared by wet chemical synthesis

    Czech Academy of Sciences Publication Activity Database

    Buršík, Jiří; Škoda, D.; Vykoukal, V.; Sopoušek, J.

    Ostrava: Tanger Ltd, 2011, Paper no. 1114. ISBN 978-80-87294-23-9. [NANOCON 2011. International Conference /3./. Brno (CZ), 21.09.2011-23.09.2011] R&D Projects: GA ČR(CZ) GA106/09/0700 Institutional research plan: CEZ:AV0Z20410507 Keywords : solder * nanopowder * electron microscopy Subject RIV: JG - Metallurgy

  5. Genetic dissection of drought and heat tolerance in chickpea through genome-wide and candidate gene-based association mapping approaches.

    Science.gov (United States)

    Thudi, Mahendar; Upadhyaya, Hari D; Rathore, Abhishek; Gaur, Pooran Mal; Krishnamurthy, Lakshmanan; Roorkiwal, Manish; Nayak, Spurthi N; Chaturvedi, Sushil Kumar; Basu, Partha Sarathi; Gangarao, N V P R; Fikre, Asnake; Kimurto, Paul; Sharma, Prakash C; Sheshashayee, M S; Tobita, Satoshi; Kashiwagi, Junichi; Ito, Osamu; Killian, Andrzej; Varshney, Rajeev Kumar

    2014-01-01

    To understand the genetic basis of tolerance to drought and heat stresses in chickpea, a comprehensive association mapping approach has been undertaken. Phenotypic data were generated on the reference set (300 accessions, including 211 mini-core collection accessions) for drought tolerance related root traits, heat tolerance, yield and yield component traits from 1-7 seasons and 1-3 locations in India (Patancheru, Kanpur, Bangalore) and three locations in Africa (Nairobi, Egerton in Kenya and Debre Zeit in Ethiopia). Diversity Array Technology (DArT) markers equally distributed across chickpea genome were used to determine population structure and three sub-populations were identified using admixture model in STRUCTURE. The pairwise linkage disequilibrium (LD) estimated using the squared-allele frequency correlations (r2; when r2<0.20) was found to decay rapidly with the genetic distance of 5 cM. For establishing marker-trait associations (MTAs), both genome-wide and candidate gene-sequencing based association mapping approaches were conducted using 1,872 markers (1,072 DArTs, 651 single nucleotide polymorphisms [SNPs], 113 gene-based SNPs and 36 simple sequence repeats [SSRs]) and phenotyping data mentioned above employing mixed linear model (MLM) analysis with optimum compression with P3D method and kinship matrix. As a result, 312 significant MTAs were identified and a maximum number of MTAs (70) was identified for 100-seed weight. A total of 18 SNPs from 5 genes (ERECTA, 11 SNPs; ASR, 4 SNPs; DREB, 1 SNP; CAP2 promoter, 1 SNP and AMDH, 1SNP) were significantly associated with different traits. This study provides significant MTAs for drought and heat tolerance in chickpea that can be used, after validation, in molecular breeding for developing superior varieties with enhanced drought and heat tolerance. PMID:24801366

  6. Genetic dissection of drought and heat tolerance in chickpea through genome-wide and candidate gene-based association mapping approaches.

    Directory of Open Access Journals (Sweden)

    Mahendar Thudi

    Full Text Available To understand the genetic basis of tolerance to drought and heat stresses in chickpea, a comprehensive association mapping approach has been undertaken. Phenotypic data were generated on the reference set (300 accessions, including 211 mini-core collection accessions for drought tolerance related root traits, heat tolerance, yield and yield component traits from 1-7 seasons and 1-3 locations in India (Patancheru, Kanpur, Bangalore and three locations in Africa (Nairobi, Egerton in Kenya and Debre Zeit in Ethiopia. Diversity Array Technology (DArT markers equally distributed across chickpea genome were used to determine population structure and three sub-populations were identified using admixture model in STRUCTURE. The pairwise linkage disequilibrium (LD estimated using the squared-allele frequency correlations (r2; when r2<0.20 was found to decay rapidly with the genetic distance of 5 cM. For establishing marker-trait associations (MTAs, both genome-wide and candidate gene-sequencing based association mapping approaches were conducted using 1,872 markers (1,072 DArTs, 651 single nucleotide polymorphisms [SNPs], 113 gene-based SNPs and 36 simple sequence repeats [SSRs] and phenotyping data mentioned above employing mixed linear model (MLM analysis with optimum compression with P3D method and kinship matrix. As a result, 312 significant MTAs were identified and a maximum number of MTAs (70 was identified for 100-seed weight. A total of 18 SNPs from 5 genes (ERECTA, 11 SNPs; ASR, 4 SNPs; DREB, 1 SNP; CAP2 promoter, 1 SNP and AMDH, 1SNP were significantly associated with different traits. This study provides significant MTAs for drought and heat tolerance in chickpea that can be used, after validation, in molecular breeding for developing superior varieties with enhanced drought and heat tolerance.

  7. Thermal Fatigue Evaluation of Pb-Free Solder Joints: Results, Lessons Learned, and Future Trends

    Science.gov (United States)

    Coyle, Richard J.; Sweatman, Keith; Arfaei, Babak

    2015-09-01

    Thermal fatigue is a major source of failure of solder joints in surface mount electronic components and it is critically important in high reliability applications such as telecommunication, military, and aeronautics. The electronic packaging industry has seen an increase in the number of Pb-free solder alloy choices beyond the common near-eutectic Sn-Ag-Cu alloys first established as replacements for eutectic SnPb. This paper discusses the results from Pb-free solder joint reliability programs sponsored by two industry consortia. The characteristic life in accelerated thermal cycling is reported for 12 different Pb-free solder alloys and a SnPb control in 9 different accelerated thermal cycling test profiles in terms of the effects of component type, accelerated thermal cycling profile and dwell time. Microstructural analysis on assembled and failed samples was performed to investigate the effect of initial microstructure and its evolution during accelerated thermal cycling test. A significant finding from the study is that the beneficial effect of Ag on accelerated thermal cycling reliability (measured by characteristic lifetime) diminishes as the severity of the accelerated thermal cycling, defined by greater ΔT, higher peak temperature, and longer dwell time increases. The results also indicate that all the Pb-free solders are more reliable in accelerated thermal cycling than the SnPb alloy they have replaced. Suggestions are made for future work, particularly with respect to the continued evolution of alloy development for emerging application requirements and the value of using advanced analytical methods to provide a better understanding of the effect of microstructure and its evolution on accelerated thermal cycling performance.

  8. Soldered joints—an essential component of demountable high temperature superconducting fusion magnets

    Science.gov (United States)

    Tsui, Yeekin; Surrey, Elizabeth; Hampshire, Damian

    2016-07-01

    Demountable superconducting magnet coils would offer significant benefits to commercial nuclear fusion power plants. Whether large pressed joints or large soldered joints provide the solution for demountable fusion magnets, a critical component or building block for both will be the many, smaller-scale joints that enable the supercurrent to leave the superconducting layer, cross the superconducting tape and pass into the solder that lies between the tape and the conductor that eventually provides one of the demountable surfaces. This paper considers the electrical and thermal properties of this essential component part of demountable high temperature superconducting (HTS) joints by considering the fabrication and properties of jointed HTSs consisting of a thin layer of solder (In52Sn48 or Pb38Sn62) sandwiched between two rare-earth-Ba2Cu3O7 (REBCO) second generation HTS coated conductors (CCs). The HTS joints are analysed using numerical modelling, critical current and resistivity measurements on the joints from 300 to 4.2 K in applied magnetic fields up to 12 T, as well as scanning electron microscopy studies. Our results show that the copper/silver layers significantly reduce the heating in the joints to less than a few hundred mK. When the REBCO alone is superconducting, the joint resistivity (R J) predominantly has two sources, the solder layer and an interfacial resistivity at the REBCO/silver interface (∼25 nΩ cm2) in the as-supplied CCs which together have a very weak magnetoresistance in fields up to 12 T. We achieved excellent reproducibility in the R J of the In52Sn48 soldered joints of better than 10% at temperatures below T c of the REBCO layer which can be compared to variations of more than two orders of magnitude in the literature. We also show that demountable joints in fusion energy magnets are viable and need only add a few percent to the total cryogenic cost for a fusion tokamak.

  9. Nanoindentation measurements and mechanical testing of as-soldered and aged Sn-0.7Cu lead-free miniature joints

    International Nuclear Information System (INIS)

    Nanoindentation testing has been used to analyze local mechanical parameter changes across interfaces formed between the solder and the Cu substrate and also in the eutectic solder, in miniature lead-free soldered joints. Effects of plastic deformation and aging were investigated. The lead-free solder alloy used in this study is commercially available and has nominal composition by weight of 99.3% Sn and 0.7% Cu. During aging, the joints were exposed to 150 deg. C for 1000 h in an inert atmosphere. Tensile testing of as-soldered miniature joints shows strong positive dependence of the plastic flow stresses on strain rate, meaning that the stresses increase with strain rate. Similar behavior was observed for aged miniature soldered joints with ∼10% decrease in the level of maximum stresses, compared to as-soldered joints. Indentation hardness and modulus were measured in soldered joint components, in the as-soldered, aged conditions, and tensile tested with strain rates in the range of 1.8 x 10-3-1.8 x 10-1 s-1. Scanning electron and optical microscopy were employed to analyze the fracture paths and microstructure of the as-soldered and aged miniature joints, as well as the location and shape of the indentations. The measured indentation hardness and modulus agreed well with previous studies on similar alloys. The tested modulus of the intermetallic phase in the eutectic area exhibited a considerable reduction as compared to the intermetallic phase at the interface between the solder and the Cu substrate. Strain rate strongly influences local mechanics: for both as-soldered and deformed miniature joints; close to the fracture face in the eutectic solder, the indentation modulus values were 53% higher and hardness more than 100% higher in joints exposed to the highest strain rate relative to the smallest rate.

  10. Water-cooled hard-soldered kilowatt laser diode arrays operating at high duty cycle

    Science.gov (United States)

    Klumel, Genady; Karni, Yoram; Oppenhaim, Jacob; Berk, Yuri; Shamay, Moshe; Tessler, Renana; Cohen, Shalom; Risemberg, Shlomo

    2010-04-01

    High brightness laser diode arrays are increasingly found in defense applications either as efficient optical pumps or as direct energy sources. In many instances, duty cycles of 10- 20 % are required, together with precise optical collimation. System requirements are not always compatible with the use of microchannel based cooling, notwithstanding their remarkable efficiency. Simpler but effective solutions, which will not involve high fluid pressure drops as well as deionized water, are needed. The designer is faced with a number of challenges: effective heat removal, minimization of the built- in and operational stresses as well as precise and accurate fast axis collimation. In this article, we report on a novel laser diode array which includes an integral tap water cooling system. Robustness is achieved by all around hard solder bonding of passivated 940nm laser bars. Far field mapping of the beam, after accurate fast axis collimation will be presented. It will be shown that the design of water cooling channels , proper selection of package materials, careful design of fatigue sensitive parts and active collimation technique allow for long life time and reliability, while not compromising the laser diode array efficiency, optical power density ,brightness and compactness. Main performance characteristics are 150W/bar peak optical power, 10% duty cycle and more than 50% wall plug efficiency with less than 1° fast axis divergence. Lifetime of 0.5 Gshots with less than 10% power degradation has been proved. Additionally, the devices have successfully survived harsh environmental conditions such as thermal cycling of the coolant temperature and mechanical shocks.

  11. Planetary Candidates Observed by Kepler. VII. The First Fully Uniform Catalog Based on the Entire 48-month Data Set (Q1–Q17 DR24)

    Science.gov (United States)

    Coughlin, Jeffrey L.; Mullally, F.; Thompson, Susan E.; Rowe, Jason F.; Burke, Christopher J.; Latham, David W.; Batalha, Natalie M.; Ofir, Aviv; Quarles, Billy L.; Henze, Christopher E.; Wolfgang, Angie; Caldwell, Douglas A.; Bryson, Stephen T.; Shporer, Avi; Catanzarite, Joseph; Akeson, Rachel; Barclay, Thomas; Borucki, William J.; Boyajian, Tabetha S.; Campbell, Jennifer R.; Christiansen, Jessie L.; Girouard, Forrest R.; Haas, Michael R.; Howell, Steve B.; Huber, Daniel; Jenkins, Jon M.; Li, Jie; Patil-Sabale, Anima; Quintana, Elisa V.; Ramirez, Solange; Seader, Shawn; Smith, Jeffrey C.; Tenenbaum, Peter; Twicken, Joseph D.; Zamudio, Khadeejah A.

    2016-05-01

    We present the seventh Kepler planet candidate (PC) catalog, which is the first catalog to be based on the entire, uniformly processed 48-month Kepler data set. This is the first fully automated catalog, employing robotic vetting procedures to uniformly evaluate every periodic signal detected by the Q1–Q17 Data Release 24 (DR24) Kepler pipeline. While we prioritize uniform vetting over the absolute correctness of individual objects, we find that our robotic vetting is overall comparable to, and in most cases superior to, the human vetting procedures employed by past catalogs. This catalog is the first to utilize artificial transit injection to evaluate the performance of our vetting procedures and to quantify potential biases, which are essential for accurate computation of planetary occurrence rates. With respect to the cumulative Kepler Object of Interest (KOI) catalog, we designate 1478 new KOIs, of which 402 are dispositioned as PCs. Also, 237 KOIs dispositioned as false positives (FPs) in previous Kepler catalogs have their disposition changed to PC and 118 PCs have their disposition changed to FPs. This brings the total number of known KOIs to 8826 and PCs to 4696. We compare the Q1–Q17 DR24 KOI catalog to previous KOI catalogs, as well as ancillary Kepler catalogs, finding good agreement between them. We highlight new PCs that are both potentially rocky and potentially in the habitable zone of their host stars, many of which orbit solar-type stars. This work represents significant progress in accurately determining the fraction of Earth-size planets in the habitable zone of Sun-like stars. The full catalog is publicly available at the NASA Exoplanet Archive.

  12. Identification of candidate agents active against N. ceranae infection in honey bees: establishment of a medium throughput screening assay based on N. ceranae infected cultured cells.

    Directory of Open Access Journals (Sweden)

    Sebastian Gisder

    Full Text Available Many flowering plants in both natural ecosytems and agriculture are dependent on insect pollination for fruit set and seed production. Managed honey bees (Apis mellifera and wild bees are key pollinators providing this indispensable eco- and agrosystem service. Like all other organisms, bees are attacked by numerous pathogens and parasites. Nosema apis is a honey bee pathogenic microsporidium which is widely distributed in honey bee populations without causing much harm. Its congener Nosema ceranae was originally described as pathogen of the Eastern honey bee (Apis cerana but jumped host from A. cerana to A. mellifera about 20 years ago and spilled over from A. mellifera to Bombus spp. quite recently. N. ceranae is now considered a deadly emerging parasite of both Western honey bees and bumblebees. Hence, novel and sustainable treatment strategies against N. ceranae are urgently needed to protect honey and wild bees. We here present the development of an in vitro medium throughput screening assay for the identification of candidate agents active against N. ceranae infections. This novel assay is based on our recently developed cell culture model for N. ceranae and coupled with an RT-PCR-ELISA protocol for quantification of N. ceranae in infected cells. The assay has been adapted to the 96-well microplate format to allow automated analysis. Several substances with known (fumagillin or presumed (surfactin or no (paromomycin activity against N. ceranae were tested as well as substances for which no data concerning N. ceranae inhibition existed. While fumagillin and two nitroimidazoles (metronidazole, tinidazole totally inhibited N. ceranae proliferation, all other test substances were inactive. In summary, the assay proved suitable for substance screening and demonstrated the activity of two synthetic antibiotics against N. ceranae.

  13. Soldering of Bi-2223/Ag high temperature superconducting tapes with Sn-Pb-Bi-Ag alloy paste

    International Nuclear Information System (INIS)

    Soldered joints of Bi-2223/Ag-sheathed high temperature superconducting multifilamentary tapes were fabricated using 63 wt.%Sn-34 wt.%Pb-1 wt.%Bi-2 wt.%Ag paste. The soldered joints were observed by scanning electron microscope (SEM) and X-ray diffraction (XRD). Moreover, the electrical properties of joints were evaluated by current-voltage curves, and the tensile strengths of the joints were also tested. The results show that the soldered joint consists of Ag sheath - Ag3Sn compound layer - PbSn2 and Ag3Sn solder layer - Ag3Sn compound layer - Ag sheath. The joints are obeyed with Ohms Law and the magnitude of the joint resistance, which deceases with the increase of the overlap length, can reach the order of 10-8 Ω. The tensile strength of the joints with a brittle fracture mode is a little lower than that of the original tapes.

  14. Soldering of Bi-2223/Ag high temperature superconducting tapes with Sn-Pb-Bi-Ag alloy paste

    Science.gov (United States)

    Wei, Guo; Guisheng, Zou; Aiping, Wu; Hailin, Bai; Jialie, Ren

    2010-01-01

    Soldered joints of Bi-2223/Ag-sheathed high temperature superconducting multifilamentary tapes were fabricated using 63 wt.%Sn-34 wt.%Pb-1 wt.%Bi-2 wt.%Ag paste. The soldered joints were observed by scanning electron microscope (SEM) and X-ray diffraction (XRD). Moreover, the electrical properties of joints were evaluated by current-voltage curves, and the tensile strengths of the joints were also tested. The results show that the soldered joint consists of Ag sheath - Ag 3Sn compound layer - PbSn 2 and Ag 3Sn solder layer - Ag 3Sn compound layer - Ag sheath. The joints are obeyed with Ohms Law and the magnitude of the joint resistance, which deceases with the increase of the overlap length, can reach the order of 10 -8 Ω. The tensile strength of the joints with a brittle fracture mode is a little lower than that of the original tapes.

  15. Influence of laminate type on tin whisker growth in tin-rich lead-free solder alloys

    International Nuclear Information System (INIS)

    This paper describes variations in whisker growth on the surface of tin-rich, lead-free alloys soldered on a Cu layer depending on the laminate used for the printed circuit board, which can be either glass-epoxy or paper-phenol. The structure of the glass-epoxy laminate surface is characterized by spatial nonuniformity caused by the regular structure formed by regions of glass fibers and resin in the top layer of the laminate. The higher value of thermal expansion of the resin than of the glass fiber means that the area of the resin expands more than that of the glass fiber. This causes local compressive stress in the solder layer and as a result promotes whisker growth in the area of the alloy soldered on the Cu layer over the glass fiber. This effect does not occur on the surface of an alloy soldered on Cu layer over a paper-phenol laminate.

  16. Influence of laminate type on tin whisker growth in tin-rich lead-free solder alloys

    Energy Technology Data Exchange (ETDEWEB)

    Skwarek, Agata, E-mail: askwarek@ite.waw.pl [Department of Microelectronics, Institute of Electron Technology, Zablocie 39, Cracow (Poland); Pluska, Mariusz; Czerwinski, Andrzej [Department of Materials and Semiconductor Structures Research, Institute of Electron Technology, Lotnikow 32/46, Warsaw (Poland); Witek, Krzysztof [Department of Implementation and Production, Institute of Electron Technology, Zablocie 39, Cracow (Poland)

    2012-09-01

    This paper describes variations in whisker growth on the surface of tin-rich, lead-free alloys soldered on a Cu layer depending on the laminate used for the printed circuit board, which can be either glass-epoxy or paper-phenol. The structure of the glass-epoxy laminate surface is characterized by spatial nonuniformity caused by the regular structure formed by regions of glass fibers and resin in the top layer of the laminate. The higher value of thermal expansion of the resin than of the glass fiber means that the area of the resin expands more than that of the glass fiber. This causes local compressive stress in the solder layer and as a result promotes whisker growth in the area of the alloy soldered on the Cu layer over the glass fiber. This effect does not occur on the surface of an alloy soldered on Cu layer over a paper-phenol laminate.

  17. Optimization of Suture-Free Laser-Assisted Vessel Repair by Solder-Doped Electrospun Poly(ε-caprolactone) Scaffold

    OpenAIRE

    Pabittei, D.R.; M. Heger; Beek, J.F.; Tuijl, van, B.A.J.; Simonet, M; Van der Wal; Mol, de, B.A.; Balm, R

    2011-01-01

    Poor welding strength constitutes an obstacle in the clinical employment of laser-assisted vascular repair (LAVR) and anastomosis. We therefore investigated the feasibility of using electrospun poly(ε-caprolactone) (PCL) scaffold as reinforcement material in LAVR of medium-sized vessels. In vitro solder-doped scaffold LAVR (ssLAVR) was performed on porcine carotid arteries or abdominal aortas using a 670-nm diode laser, a solder composed of 50% bovine serum albumin and 0.5% methylene blue, an...

  18. Influence of supply of heat to cobalt-chromium frameworks during soldering and subsequent hardening heat treatment of wrought clasps.

    Science.gov (United States)

    Eriksson, T; Sjögren, G; Bergman, M

    1983-01-01

    Retentive clasp arms of wrought gold alloy wire were soldered to frameworks made of three dental cobalt-chromium alloys. The clasps were then subjected to a conventional hardening heat treatment. Microstructure and hardness of the cobalt-chromium alloys were determined before and after these operations. The results reveal that the supply of heat during soldering and hardening heat treatment of the clasp does not influence the microstructure and hardness of the cobalt-chromium alloys. PMID:6134347

  19. Creep behavior of near-peritectic Sn-5Sb solders containing small amount of Ag and Cu

    International Nuclear Information System (INIS)

    Research highlights: → We add small amount of Ag and Cu into the Sn-5Sb solder alloy. → We examine changes in the microstructure and creep properties of the solder alloys. → The Sn-5Sb-0.7Cu solder alloy shows the highest creep resistance compared with the other two alloys. → The presence of hard Cu6Sn5 and fine SbSn IMCs in the Sn-5Sb-0.7Cu alloy increased the resistance to dislocation movement, and improved the creep properties. - Abstract: Sn-5%Sb is one of the materials considered for replacing Pb-bearing alloys in electronic packaging. In the present study, the effects of minor additives of Ag and Cu on the as-cast microstructure and creep properties of the Sn-5Sb solder alloy are investigated by means of optical microscopy (OM), scanning electron microscopy (SEM), energy dispersive X-ray spectroscope (EDS) and tensile tests. Results show that addition of Ag and Cu resulted not only in the formation of new Ag3Sn and Cu6Sn5 intermetallic compounds (IMCs), but also in the refinement of the grain size of Sn-5Sb solder. Accordingly, the creep properties of the Ag or Cu-containing solder alloys are notably improved. Attention has been paid to the role of IMCs on creep behavior. The lead-free Sn-5Sb-0.7Cu solder shows superior creep performance over the other two solders in terms of much higher creep resistance and vastly elongated creep fracture lifetime. An analysis of the creep behavior at elevated temperatures suggested that the presence of hard Cu6Sn5 and fine SbSn IMCs in the Sn-5Sb-0.7Cu alloy increases the resistance to dislocation movement, which improves the creep properties.

  20. Electromigration and solid state aging of flip chip solder joints and analysis of tin whisker on lead-frame

    Science.gov (United States)

    Lee, Taekyeong

    Electromigration and solid state aging in flip chip joint, and whisker on lead frame of Pb-containing (eutectic SnPb) and Pb-free solders (SnAg 3.5, SnAg3.8Cu0.7, and SnCu0.7), have been studied systematically, using Scanning Electron Microscopy (SEM), Energy Dispersive X-ray Analysis (EDX), and synchrotron radiation. The high current density in flip chip joint drives the diffusion of atoms of eutectic SnPb and SnAgCu. A marker is used to measure the diffusion flux in a half cross-sectioned solder joint. SnAgCu shows higher resistance against electromigration than eutectic SnPb. In the half cross-sectioned solder joint, void growth is the dominant failure mechanism. However, the whole solder balls in the underfill show that the failure mechanism is a result from the dissolution of electroless Ni under bump metallization (UBM) of about 10 mum thickness. The growth rate between intermetallic compounds in molten and solid solders differed by four orders of magnitude. In liquid solder, the growth rate is about 1 mum/min; the growth rate in solid solder is only about 10 -4 mum/min. The difference is not resulting from factors of thermodynamics, which is the change of Gibbs free energy before and after intermetallic compound formation, but from kinetic factors, which is the rate of change of Gibbs free energy. Even though the difference in growth rate between eutectic SnPb and Pb-free solders during solid state aging was found, the reason behind such difference shown is unclear. The orientation and stress levels of whiskers are measured by white X-ray of synchrotron radiation. The growth direction is nearly parallel to one of the principal axes of tin. The compressive stress level is quite low because the residual stress is relaxed by the whisker growth.

  1. Evaluation of the Bondability of the Epoxy-Enhanced Sn-58Bi Solder with ENIG and ENEPIG Surface Finishes

    Science.gov (United States)

    Myung, Woo-Ram; Kim, Yongil; Jung, Seung-Boo

    2015-11-01

    The effect of different surface finishes, electroless nickel immersion gold (ENIG) and electroless nickel electroless palladium immersion gold (ENEPIG), on the mechanical properties of Sn-58Bi bumps made with solder paste enhanced with epoxy were investigated. The microstructure and fracture surfaces were observed with scanning electron microscopy, and the compositions of the IMC and solder were measured using energy dispersive spectrometry and an electron probe micro-analyzer (EPMA). To evaluate the mechanical properties, low-speed shear tests and board-level drop tests were performed. The result of the shear tests showed that the bonding strength of the epoxy-enhanced Sn-58Bi solder bumps was higher than that of Sn-58Bi solder for all surface finishes, because of the epoxy surrounding the solder, and the fracture surfaces of epoxy-enhanced Sn-58Bi indicated ductile fracture in the solder joint. However, the result of the drop tests showed that samples with the ENIG and ENEPIG surface finishes had lower drop numbers compared to the sample without these surface finishes. The lower performance resulted from insufficient ejection of epoxy from the ENIG and ENEPIG surface finishes during reflow, which reduced the interfacial bonding area.

  2. Immunogenicity of a virosomally-formulated Plasmodium falciparum GLURP-MSP3 chimeric protein-based malaria vaccine candidate in comparison to adjuvanted formulations

    DEFF Research Database (Denmark)

    Tamborrini, Marco; Stoffel, Sabine A; Westerfeld, Nicole; Amacker, Mario; Theisen, Michael; Zurbriggen, Rinaldo; Pluschke, Gerd

    2011-01-01

    In clinical trials, immunopotentiating reconstituted influenza virosomes (IRIVs) have shown great potential as a versatile antigen delivery platform for synthetic peptides derived from Plasmodium falciparum antigens. This study describes the immunogenicity of a virosomally-formulated recombinant ...... fusion protein comprising domains of the two malaria vaccine candidate antigens MSP3 and GLURP....

  3. Enhancement on wettability and intermetallic compound formation with an addition of Al on Sn-0.7Cu lead-free solder fabricated via powder metallurgy method

    Science.gov (United States)

    Adli, Nisrin; Razak, Nurul Razliana Abdul; Saud, Norainiza

    2016-07-01

    Due to the toxicity of lead (Pb), the exploration of another possibility for lead-free solder is necessary. Nowadays, SnCu alloys are being established as one of the lead-free solder alternatives. In this study, Sn-0.7Cu lead-free solder with an addition of 1wt% and 5wt% Al were investigated by using powder metallurgy method. The effect of Al addition on the wettability and intermetallic compound thickness (IMC) of Sn-0.7Cu-Al lead-free solder were appraised. Results showed that Al having a high potential to enhance Sn-0.7Cu lead-free solder due to its good wetting and reduction of IMC thickness. The contact angle and IMC of the Sn-0.7Cu-Al lead-free solder were decreased by 14.32% and 40% as the Al content increased from 1 wt% to 5 wt%.

  4. Dark matter candidates

    International Nuclear Information System (INIS)

    One of the simplest, yet most profound, questions we can ask about the Universe is, how much stuff is in it, and further what is that stuff composed of? Needless to say, the answer to this question has very important implications for the evolution of the Universe, determining both the ultimate fate and the course of structure formation. Remarkably, at this late date in the history of the Universe we still do not have a definitive answer to this simplest of questions---although we have some very intriguing clues. It is known with certainty that most of the material in the Universe is dark, and we have the strong suspicion that the dominant component of material in the Cosmos is not baryons, but rather is exotic relic elementary particles left over from the earliest, very hot epoch of the Universe. If true, the Dark Matter question is a most fundamental one facing both particle physics and cosmology. The leading particle dark matter candidates are: the axion, the neutralino, and a light neutrino species. All three candidates are accessible to experimental tests, and experiments are now in progress. In addition, there are several dark horse, long shot, candidates, including the superheavy magnetic monopole and soliton stars. 13 refs

  5. Rate-dependent Constitutive Model for Lead-free Solders Considering Damage Effect%考虑损伤效应的无铅焊锡材料的率相关本构模型

    Institute of Scientific and Technical Information of China (English)

    秦飞; 安彤; 王旭明

    2013-01-01

    In this paper, the damage effect was considered into the impact process of lead-free solder specimens. Based on the experimental data, the modified rate-dependent Johnson-Cook model for the Sn3.OAgO.5Cu and Sn3. 5Ag lead-free solders were derived. The stress-strain curves obtained from the modified Johnson-Cook material models and the experiments agreed quite well with each other. It indicates that presented modified Johnson-Cook models are suitable to describe the dynamic behavior of the two lead-free solder materials.%考虑冲击过程中无铅焊锡材料试件中的损伤影响,根据实验数据确定了损伤演化参数,对原模型进行了修正,给出了Sn3.0Ag0.5Cu和Sn3.5Ag两种无铅焊锡材料考虑损伤效应的率相关本构模型.结果表明,修正后的模型与实验结果吻合较好.

  6. 热循环条件下SnAgCu钎料损伤行为的研究%Damage Behavior of SnAgCu Solder under Thermal Cycling

    Institute of Scientific and Technical Information of China (English)

    肖慧; 李晓延; 严永长; 刘娜; 史耀武

    2013-01-01

    The failure of solder joints under thermal cycling is mainly as a result of progressive damage process of solder materials.The objective of this study was to investigate the damage behavior of SnAgCu solder under thermal cycling condition.A damage model was proposed and employed to simulate the thermal cycling behavior of SnAgCu solder.The proposed damage evolution law was based on continuum damage mechanics and an interaction between creep and fatigue.Thermo-mechanical cycling and thermal cycling tests were conducted for model parameter determination.A special bimetallic load frame with single joint-shear solder sample was designed and used to study the damage evolution behavior of SnAgCu solder.The damage variable D=1-R0/R was selected and measured for the single joint-shear solder sample every dozens of cycles during thermal cycling tests to verify the model.The damage evolution law was deduced as power function with thermal cycles and the results show that the experimental damage data can be fitted reasonably well by the relationship as the damage model proposed.The microstructure evolution of SnAgCu solder under thermal cycling was observed by Scanning Electron Microscopy and the damage mechanism was analyzed.%电子封装焊点的热循环失效是焊点材料损伤逐步发展的结果,本工作旨在对SnAgCu钎料的热循环损伤失效行为进行研究.以连续损伤力学理论为基础,提出了一种适用于热循环条件下SnAgCu钎料蠕变-疲劳交互作用的损伤模型.据此,设计了热力循环实验和热循环实验用以标定损伤模型相关参量.自行设计了双金属剪切加载装置并结合温度循环实验,对SnAgCu钎料的热力耦合损伤行为进行了深入研究.以电阻变化率作为损伤变量,并在热循环的不同周次测量试样的损伤值从而验证损伤模型.结果表明:所提出的幂函数形式的损伤模型能较好的描述SnAgCu钎料的热循环损伤演变.最后,对热循环条件下Sn

  7. Reaction Between Thin Gold Wires and Pb-Sn-In Solder (37.5%, 37.5%, 25%), Part A: The Radial Reaction Inside The Solder Mounds, Its Linear Reaction Model, Statistical Variation of Reaction Rate, and Induced Structural Changes In The Solder Mounds.

    Energy Technology Data Exchange (ETDEWEB)

    Siekhaus, W J

    2011-01-19

    Thermodynamics favors the reaction between indium and gold, since the heat of formation of AuIn{sub 2} is 6 kcal/mole, substantially larger than the heat of formation of any other possible reaction product. Thermodynamic equilibrium between gold and the elements in the solder mound is reached only when ALL gold is converted to AuIn{sub 2}. There are two aspects to this conversion: (A) the reaction WITHIN the solder mound (called here 'radial reaction') and (B) the reaction OUTSIDE the solder mound (called here 'axial reaction') and the transition from (A) to (B). The reaction between thin gold detonator wires and the In/Pb/Sn solder mound in older detonators has been looked at repeatedly. There are, in addition, two studies which look at the reaction between indium and gold in planar geometry. All data are shown in tables I to V. It is the objective of this section dealing with aspect (A), to combine all of these results into a reaction model and to use this reaction model to reliably and conservatively predict the gold-solder reaction rate of soldered gold bridge-wires as a function of storage temperature and time.

  8. CASE via MS: Ranking Structure Candidates by Mass Spectra

    OpenAIRE

    Kerber, Adalbert; Meringer, Markus; Rücker, Christoph

    2006-01-01

    Two important tasks in computer-aided structure elucidation (CASE) are the generation of candidate structures from a given molecular formula, and the ranking of structure candidates according to compatibility with an experimental spectrum. Candidate ranking with respect to electron impact mass spectra is based on virtual fragmentation of a candidate structure and comparison of the fragments’ isotope distributions against the spectrum of the unknown compound, whence a structure–spectrum compat...

  9. Significantly Improved Mechanical Properties of Bi- Sn Solder Alloys by Ag- Doping

    Science.gov (United States)

    McCormack, M.; Chen, H. S.; Kammlott, G. W.; Jin, S.

    1997-08-01

    The addition of small amounts of Ag (less than ~;0.5 wt. %) is found to significantly improve the ductility of the binary Bi-Sn eutectic solder. The ductility improvement, more than a threefold increase in tensile elongation, is observed even at a relatively high strain rate (0.01 s-1). As the Bi-Sn binary eutectic alloy tends to fail catastrophically by brittle fracture at high strain rates, the reduced strain-rate sensitivity in the Ag-containing alloy is beneficial for improving solder reliability on sudden impacting as might be encountered during device assembly, shipping, or thermal shock/cycling. The observed increase in alloy ductility by Ag additions is attributed to a substantial refinement of the solidification microstructure.

  10. Intense generation of respirable metal nanoparticles from a low-power soldering unit

    International Nuclear Information System (INIS)

    Highlights: • Intense generation of nanoparticles in the breathing range from a flux-soldering unit is detected. • Coagulation in the aerosol phase leads to 200-nm respirable nanoparticles up to 30 min after operation. • Nanoparticle concentration in the working environment depends on the presence of ambient air. • Metal-containing nanoparticles are collected in TEM grids and filters in the hundreds of nanometer range. -- Abstract: Evidence of intense nanoparticle generation from a low power (45 W) flux soldering unit is presented. This is a familiar device often used in daily life, including home repairs and school electronic laboratories. We demonstrate that metal-containing nanoparticles may reach high concentrations (ca. 106 particles/cm3) within the breathing range of the operator, with initial size distributions centered at 35–60 nm The morphological and chemical analysis of nanoparticle agglomerates collected on TEM grids and filters confirms their multiparticle structure and the presence of metals

  11. Appendix to the report from the low-residue soldering task force: Phase 2 results

    Energy Technology Data Exchange (ETDEWEB)

    Iman, R.L.; Anderson, D.J.; Huffman, D.D. [and others

    1995-12-01

    The LRSTF report for Phase I of its evaluation of low-residue soldering was issued in June 1995. This Appendix summarizes the results of follow-on testing performed in Phase II and compares electrical test results for both phases. Deliberate decisions were made by the LRSTF in Phase I to challenge the design guideline limits in MILSTD-275, Printed Wiring for Electronic Equipment The LRSTF considered this approach to produce a ``worst case`` design and provide useful information about the robustness of LR soldering processes. As such, good design practices were sometimes deliberately violated in designing the LRSTF board. This approach created some anomalies for both LR boards and RMA/cleaned controls. Phase II testing verified that problems that affected both RMA/cleaned and LR boards in Phase I were design related.

  12. Fluxless eutectic bonding of GaAs-on-Si by using Ag/Sn solder

    Science.gov (United States)

    Eo, Sung-Hwa; Kim, Dae-Seon; Jeong, Ho-Jung; Jang, Jae-Hyung

    2013-11-01

    Fluxless GaAs-on-Si wafer bonding using Ag/Sn solder was investigated to realize uniform and void-free heterogeneous material integration. The effects of the diffusion barrier, Ag/Sn thickness, and Ar plasma treatment were studied to achieve the optimal fluxless bonding process. Pt on a GaAs wafer and Mo on a Si wafer act as diffusion barriers by preventing the flow of Ag/Sn solder into both the wafers. The bonding strength is closely related to the Ag/Sn thickness and Ar plasma treatment. A shear strength test was carried out to investigate the bonding strength. Under identical bonding conditions, the Ag/Sn thickness was optimized to achieve higher bonding strength and to avoid the formation of voids due to thermal stress. An Ar plasma pretreatment process improved the bonding strength because the Ar plasma removed carbon contaminants and metal-oxide bonds from the metal surface.

  13. Diode Lasers used in Plastic Welding and Selective Laser Soldering - Applications and Products

    Science.gov (United States)

    Reinl, S.

    Aside from conventional welding methods, laser welding of plastics has established itself as a proven bonding method. The component-conserving and clean process offers numerous advantages and enables welding of sensitive assemblies in automotive, electronic, medical, human care, food packaging and consumer electronics markets. Diode lasers are established since years within plastic welding applications. Also, soft soldering using laser radiation is becoming more and more significant in the field of direct diode laser applications. Fast power controllability combined with a contactless temperature measurement to minimize thermal damage make the diode laser an ideal tool for this application. These advantages come in to full effect when soldering of increasingly small parts in temperature sensitive environments is necessary.

  14. An Organic Metal/Silver Nanoparticle Finish on Copper for Efficient Passivation and Solderability Preservation

    Directory of Open Access Journals (Sweden)

    Wessling Bernhard

    2007-01-01

    Full Text Available AbstractFor the first time, a complex formed by polyaniline (in its organic metal form and silver has been deposited on copper in nanoparticulate form. When depositing on Cu pads of printed circuit boards it efficiently protects against oxidation and preserves its solderability. The deposited layer has a thickness of only nominally 50 nm, containing the Organic Metal (conductive polymer, polyaniline, and silver. With >90% (by volume, polyaniline (PAni is the major component of the deposited layer, Ag is present equivalent to a 4 nm thickness. The Pani–Ag complex is deposited on Cu in form of about 100 nm small particles. Morphology, electrochemical characteristics, anti-oxidation and solderability results are reported.

  15. A Novel and Facile Method to Prepare Integrated Electrospun Nanofibrous Membrane with Soldered Junctions.

    Science.gov (United States)

    Shen, Lingdi; Chen, Jiajia; Hong, Guishan; Wang, Xuefen

    2016-01-01

    Integrated electrospun nanofibrous membrane was prepared by creating soldered junctions between nanofibers via a facile strategy. Polyacrylonitrile (PAN) mixed with poly(vinylidene fluoride) (PVDF) at different ratios of PVDF were prepared in N,N'-dimethyl formamide (DMF), then electrospun to fabricate PAN/PVDF membranes. PVDF can form microgels in DMF which slows down volatile speed of DMF and affects the solidification of PAN/PVDF nanofibers. The resulting membranes were investigated by Fourier transform infrared spectroscopy, scanning electron microscopy, dynamic water contact angle and tensile testing to confirm the morphology and mechanical properties. Soldered junctions were observed between nanofibers with the increase of PVDF content. These junctions made the membrane integrated and greatly enhanced tensile strength from 5.1 to 8.1 MPa (increased by ~60%) and tensile modulus from 49.4 to 117.9 MPa (increased by ~139%) without compromising porosity when the content of PVDF increased from 0 to 60 wt%. PMID:27398532

  16. Microstructural evolution of a lead-free solder alloy Sn-Bi-Ag-Cu prepared by mechanical alloying during thermal shock and aging

    Science.gov (United States)

    Huang, M. L.; Wu, C. M. L.; Lai, J. K. L.; Chan, Y. C.

    2000-08-01

    In a previous study, a lead-free solder, Sn-6Bi-2Ag-0.5Cu, was developed by mechanical alloying. The alloy shows great potential as a lead-free solder system. In the present work, the microstructural evolution during thermal shock and aging was examined. In the as-soldered joints small bismuth (1 µm to 2 µm) and Ag3Sn (1 µm) particles were finely dispersed in a nearly pure tin matrix with a small amount of η-Cu6Sn5 phase in the bulk of solder. During thermal shock and aging microstructural evolution occurred with Cu-Sn intermetallic compound (IMC) layer growth at interface, bismuth phase coarsening and Ag3Sn phase coarsening. The microstructure of the solder appeared to be stable at high temperature. The shear strength of the present solder joint is higher than that of Sn-37Pb and Sn-3.5Ag solders. Shear failure occurred Cu-Sn IMC layer-solder interface and in the bulk of solder.

  17. Experimental and mechanical characterizations of a lead free solder alloy for electronic devices

    OpenAIRE

    Msolli, Sabeur; Dalverny, Olivier; Alexis, Joël; Karama, Moussa

    2012-01-01

    International audience Electronic power modules devices are paramount components in the aeronautical,automotive and military applications. The solder layers are the most critical parts of the module and are usually subjected in their whole life to complex loading conditions. To improve the design task, realistic thermoelastoviscoplastic and lifetime prediction models which can describe efficiently the deformation-damage of the electrical device must be chosen carefully. Some of the most co...

  18. Properties and Reliability of Solder Microbump Joints Between Si Chips and a Flexible Substrate

    Science.gov (United States)

    Ko, Yong-Ho; Kim, Min-Su; Bang, Junghwan; Kim, Taek-Soo; Lee, Chang-Woo

    2015-07-01

    Future generations of electronics are expected to include flexible, bendable, and wearable devices. There have been very few studies, however, on the bonding technology and reliability of bonding joints between a chip and a flexible substrate. In this study, we investigated the properties and reliability of joints formed with Sn-58Bi solder microbumps between a Si chip and a flexible substrate. For fine-pitch bonding, we formed Cu pillar bumps and Sn-58Bi solder microbumps with diameter of 25 μm by electroplating. The Si chips were then bonded on a flexible substrate finished with electroless nickel immersion gold (ENIG) using flip-chip technology, processing at 170°C under a force of 1 N, 2 N, or 3 N for 15 s. Cross-sectional images of bump joints were analyzed using field-emission scanning electron microscopy. While the Cu6Sn5 intermetallic compound (IMC) was formed on the Cu-pillar-bump side, another IMC, Ni3Sn4, was formed on the ENIG-substrate side. In addition, we performed a shear test, thermal shock test, and bending test to evaluate the joints' mechanical properties and reliability. The bending test was performed by a machine designed for joints on flexible substrates. Unit shear force of 2 N was the nominally highest value obtained from joints prepared under the three bonding conditions. After the thermal shock test, we observed cracks initiated at the Cu6Sn5/Sn-58Bi interface, which then propagated within the solder bumps or at the interface. In the case of the bending test, failure occurred at the Ni3Sn4/Sn-58Bi interface or within the solder bumps.

  19. Video- Soldering Iron Inserted Through a Film of Water Onboard the International Space Station (ISS)

    Science.gov (United States)

    2003-01-01

    Saturday Morning Science, the science of opportunity series of applied experiments and demonstrations, performed aboard the International Space Station (ISS) by Expedition 6 astronaut Dr. Don Pettit, revealed some remarkable findings. In this video, Dr. Pettit demonstrates the result of inserting a soldering iron into a thin film or sheet of water in space. Dr. Pettit makes comparative comments about the differences and similarities of boiling processes in space and on Earth.

  20. Solder self-assembled, surface micromachined MEMS for micromirror applications and atom trapping

    Science.gov (United States)

    McCarthy, Brian

    Solder self-assembly can be used to expand the versatility of a commercial foundry, like MEMSCAP's PolyMUMPs process. These foundries are attractive for prototyping MEMS as they can offer consistent, low cost fabrication runs by sticking to a single process and integrating multiple customers on each wafer. However, this standardization limits the utility of the process for a given application. Solder self-assembly gives back some of this versatility and expands the envelope of surface micromachining capability in the form of a simple post-process step. Here it is used to create novel micromirrors and micromirror arrays as well as to delve into the field of ultracold atom optics where the utility of MEMS as an enabling technology for atom control is explored. Two types of torsional, electrostatic micromirrors are demonstrated, both of which can achieve +/-10° of rotation. The first is a novel out-of-plane micromirror that can be rotated to a desired angle from the substrate. This integrated, on-chip assembly allows much simpler packaging technology to be used for devices that require a laser beam to be steered off-chip. Planar micromirror arrays that use solder self-assembly to tailor the electrode gap height are also demonstrated. With these designs, no special fabrication techniques are required to achieve large gap heights, and micromirrors with a variety of gap heights can even be fabricated on the same chip. Finally, solder self-assembly is used to explore how complex micro-scale structures can be used to control ultracold atoms. For this study, a MEMS version of a magneto-optical trap, the basis for most ultracold atomic systems, is used to control Rb atoms. In doing so, it provides a path for the successful integration of a number of MEMS devices in these types of systems.

  1. High temperature indentation behavior of eutectic lead-free solder materials

    OpenAIRE

    Worrack H.; Müllera W.H.

    2010-01-01

    Electronic malfunction caused by thermal stresses is one major problem in modern electronic industries. Therefore, the precise knowledge of the mechanical solder material properties as a function of temperature is required. Nanoindentation and its potential of recording load-displacement curves is a widely-used miniature test for the determination of Young’s modulus and hardness values. Furthermore, such tests can be performed in a temperature range from Room Temperature (RT) up to +500...

  2. Design and optimization of pyrazinecarboxamide-based inhibitors of diacylglycerol acyltransferase 1 (DGAT1) leading to a clinical candidate dimethylpyrazinecarboxamide phenylcyclohexylacetic acid (AZD7687).

    Science.gov (United States)

    Barlind, Jonas G; Bauer, Udo A; Birch, Alan M; Birtles, Susan; Buckett, Linda K; Butlin, Roger J; Davies, Robert D M; Eriksson, Jan W; Hammond, Clare D; Hovland, Ragnar; Johannesson, Petra; Johansson, Magnus J; Kemmitt, Paul D; Lindmark, Bo T; Morentin Gutierrez, Pablo; Noeske, Tobias A; Nordin, Andreas; O'Donnell, Charles J; Petersson, Annika U; Redzic, Alma; Turnbull, Andrew V; Vinblad, Johanna

    2012-12-13

    A new series of pyrazinecarboxamide DGAT1 inhibitors was designed to address the need for a candidate drug with good potency, selectivity, and physical and DMPK properties combined with a low predicted dose in man. Rational design and optimization of this series led to the discovery of compound 30 (AZD7687), which met the project objectives for potency, selectivity, in particular over ACAT1, solubility, and preclinical PK profiles. This compound showed the anticipated excellent pharmacokinetic properties in human volunteers. PMID:23116186

  3. Utilizing the thermodynamic nanoparticle size effects for low temperature Pb-free solder

    Energy Technology Data Exchange (ETDEWEB)

    Koppes, John P. [Department of Materials Engineering, Purdue University, West Lafayette, IN (United States); Grossklaus, Kevin A. [Department of Materials Science and Engineering, University of Michigan, Ann Arbor, MI (United States); Muza, Anthony R. [Department of Materials Engineering, Purdue University, West Lafayette, IN (United States); Revur, R. Rao; Sengupta, Suvankar [MetaMateria Partners LLC, Columbus, OH (United States); Rae, Alan [TPF Enterprises LLC, Wilson, NY (United States); Stach, Eric A. [Department of Materials Engineering, Purdue University, West Lafayette, IN (United States); Center for Functional Nanomaterials, Brookhaven National Laboratory, Upton, NY (United States); Handwerker, Carol A., E-mail: carolh@purdue.edu [Department of Materials Engineering, Purdue University, West Lafayette, IN (United States)

    2012-02-15

    Highlights: Black-Right-Pointing-Pointer In this study we developed prototype Sn nanoparticle Pb-free solder pastes. Black-Right-Pointing-Pointer Particle size, melting temperature, coalescence, and volume loading were examined. Black-Right-Pointing-Pointer DSC results showed melting point depression and nanoparticle coalescence. Black-Right-Pointing-Pointer Low metals volume loading inhibited the formation of a solder joint. - Abstract: Development of a Pb-free Sn nanosolder paste with an initial melting temperature near or below the melting temperature of eutectic Sn-Pb solder (183 Degree-Sign C) has been investigated using the size-dependent melting behavior of small particles. Three to five nanometer Sn nanoparticles were fabricated by sonochemical reduction and observed to melt at temperatures near or below 183 Degree-Sign C. Prototype nanosolder pastes were produced by combining the nanoparticles with flux and were characterized by differential scanning calorimetry (DSC) in terms of their melting, solidification, coalescence, and metal particle loading properties. The results indicate that, although target melting temperatures were achieved, nanoparticle coalescence was limited by low volume loading of the metal, due in part to the capping layer (an organic layer adsorbed on the metal surface during chemical synthesis).

  4. Sutureless microvascular anastomoses by a biodegradable laser-activated solid protein solder.

    Science.gov (United States)

    Maitz, P K; Trickett, R I; Dekker, P; Tos, P; Dawes, J M; Piper, J A; Lanzetta, M; Owen, E R

    1999-11-01

    A new sutureless technique to successfully anastomose the abdominal aorta of rats (1.3 mm in diameter) by using a fully biodegradable, laser-activated protein solder is presented. A total of 90 rats were divided into two groups randomly. In group one, the anastomoses were performed by using conventional microsuturing technique, whereas in group two, the anastomoses were performed by using a new laser welding technique. In addition, each of the two groups were divided into five subgroups and evaluated at different follow-up periods (10 minutes, 1 hour, 1 day, 1 week, and 6 weeks). At these intervals, the anastomoses were evaluated for patency and tensile strength. Three anastomoses in each subgroup were processed for light and electron microscopy. All anastomoses were found to be patent. The mean clamp time of the anastomoses performed with conventional suturing was 20.6 minutes compared with 7.2 minutes for the laser-activated welded anastomoses (p laser-welded anastomoses was higher compared with the conventional suture technique. Histologic evaluations revealed a near complete resorption of the solder after 6 weeks. The junction site of the vessel ends cannot be determined on the luminal side of the artery. In conclusion, a resorbable protein used as a solder, activated by a diode laser, can provide a reliable, safe, and rapid arterial anastomosis, which could be performed by any microsurgeon faster than conventional suturing after a short learning curve. PMID:10541175

  5. Strength of MWCNT-Reinforced 70Sn-30Bi Solder Alloys

    Science.gov (United States)

    Billah, Md Muktadir; Chen, Quanfang

    2016-01-01

    In this study, the effect of Cu-coated multi-walled carbon nanotubes (MWCNTs) on the tensile strength of 70Sn-30Bi solder alloy has been investigated. Copper was first deposited onto metal-activated MWCNTs by an electroless process and confirmed with a scanning electron microscope and energy dispersive spectroscopy. Sn-Bi alloy solder was reinforced with Cu-coated MWCNTs with additions of 0.5 wt.%, 1 wt.%, 2 wt.%, and 3 wt.%, respectively. 70Sn-30Bi solder was produced by melting pure tin and bismuth in an inert gas atmosphere. Cu-coated MWCNTs were then added into the metal matrix by cold rolling, followed by hot pressing to disperse the carbon nanotubes (CNTs) in the matrix. Tensile tests were conducted on an mechanical testing and simulation (MTS) tester. The tensile strength was found to be proportional to the addition of Cu/MWCNTs, and about 47.6% increase in tensile strength over the pure alloy has been obtained for an addition of 3 wt.% Cu/MWCNTs. The Cu coating may enhance CNT dispersion to prevent tangling.

  6. Interfacial Microstructure Evolution Between Sn-Zn Solders and Ag Substrate During Solid-State Annealing

    Science.gov (United States)

    Wang, Chao-hong; Li, Po-yi; Li, Kuan-ting

    2014-12-01

    In this study, solid-state interfacial reactions between Ag and Sn-Zn alloys with varying Zn content (0.1 wt.% to 9 wt.%) were investigated at 170°C. The reaction couples were prepared by electroplating Ag on the Sn-Zn alloy to avoid dissolution of Ag into the molten solder during soldering. The Zn content greatly influenced the reaction products and the interfacial microstructures. When the Zn content was less than 4 wt.%, Ag3Sn and AgZn layers were simultaneously formed. Notably, Zn could actively diffuse through the Ag3Sn layer and react with Ag to form the AgZn phase. With the proceeding reaction, small α-Ag particulates were produced within the AgZn phase. With 9 wt.% Zn, the dominant reactions formed Ag5Zn8 and AgZn layers. The interfacial microstructure evolved significantly with reaction time. Interface instability due to Zn depletion in the solder resulted in massive spalling of the Ag5Zn8 layer. The Ag3Sn phase was then produced next to the AgZn layer. Moreover, another reaction couple, Sn-9 wt.%Zn/Sn(15 μm)/Ag, was prepared, in which fast interdiffusion between Zn and Ag across the Sn layer was demonstrated due to the strong chemical affinity of Zn.

  7. Laser Soldering and Thermal Cycling Tests of Monolithic Silicon Pixel Chips

    CERN Document Server

    Strand, Frode Sneve

    2015-01-01

    An ALPIDE-1 monolithic silicon pixel sensor prototype has been laser soldered to a flex printed circuit using a novel interconnection technique using lasers. This technique is to be optimised to ensure stable, good quality connections between the sensor chips and the FPCs. To test the long-term stability of the connections, as well as study the effects on hit thresholds and noise in the sensor, it was thermally cycled in a climate chamber 1200 times. The soldered connections showed good qualities like even melting and good adhesion on pad/flex surfaces, and the chip remained in working condition for 1080 cycles. After this, a few connections failed, having cracks in the soldering tin, rendering the chip unusable. Threshold and noise characteristics seemed stable, except for the noise levels of sector 2 in the chip, for 1000 cycles in a temperature interval of "10^{\\circ}" and "50^{\\circ}" C. Still, further testing with wider temperature ranges and more cycles is needed to test the limitations of the chi...

  8. Hybrid atomization method suitable for production of fine spherical lead-free solder powder

    International Nuclear Information System (INIS)

    In response to the problem of environmental protection, the electronic industry is studying the lead-free alloys as substitutes for lead-containing solder alloys. At the same time, with progress in electronic devices in recent years, smaller size and higher precision are strongly demanded in electronic board connections. Therefore, it is necessary to prepare fine powders of solder paste for these connections. To produce such lead-free solder balls, a novel powder-making process, '' hybrid atomization '' that combines gas atomization and centrifugal atomization, was used. This technique produces very fine and spherical tin alloy powders with a mean diameter of about ten micrometers and very narrow size distribution with few satellites at low production cost. Taking a Sn-9mass%Zn alloy as an example, process experiments were carried out, and the effect of temperature, spray distance and disk rotating speed on the resultant powder properties were examined. The optimal processing conditions were determined from the results; the influences of the processing parameters on the properties of the obtained powders were quite different from those in the conventional atomization processes. The spherical powder with a mean diameter of 10.6 μm and a standard deviation of 1.3 ∼ 1.7 was obtained in the determined optimum condition. (author)

  9. Prospects for high-z cluster detections with Planck, based on a follow-up of 28 candidates using MegaCam@CFHT

    CERN Document Server

    van der Burg, R F J; Pratt, G W; Arnaud, M; Melin, J -B; Aghanim, N; Barrena, R; Dahle, H; Douspis, M; Ferragamo, A; Fromenteau, S; Herbonnet, R; Hurier, G; Pointecouteau, E; Rubino-Martin, J A; Streblyanska, A

    2015-01-01

    The Planck catalogue of SZ sources limits itself to a significance threshold of 4.5 to ensure a low contamination rate by false cluster candidates. This means that only the most massive clusters at redshift z>0.5, and in particular z>0.7, are expected to enter into the catalogue, with a large number of systems in that redshift regime being expected around and just below that threshold. In this paper, we follow-up a sample of SZ sources from the Planck SZ catalogues from 2013 and 2015. In the latter maps, we consider detections around and at lower significance than the threshold adopted by the Planck Collaboration. To keep the contamination rate low, our 28 candidates are chosen to have significant WISE detections, in combination with non-detections in SDSS/DSS, which effectively selects galaxy cluster candidates at redshifts $z\\gtrsim0.5$. By taking r- and z-band imaging with MegaCam@CFHT, we bridge the 4000A rest-frame break over a significant redshift range, thus allowing accurate redshift estimates of red-...

  10. Particle Dark Matter Candidates

    CERN Document Server

    Scopel, Stefano

    2007-01-01

    I give a short overview on some of the favorite particle Cold Dark Matter candidates today, focusing on those having detectable interactions: the axion, the KK-photon in Universal Extra Dimensions, the heavy photon in Little Higgs and the neutralino in Supersymmetry. The neutralino is still the most popular, and today is available in different flavours: SUGRA, nuSUGRA, sub-GUT, Mirage mediation, NMSSM, effective MSSM, scenarios with CP violation. Some of these scenarios are already at the level of present sensitivities for direct DM searches.

  11. Differential CD4+ versus CD8+ T-Cell Responses Elicited by Different Poxvirus-Based Human Immunodeficiency Virus Type 1 Vaccine Candidates Provide Comparable Efficacies in Primates▿ †

    OpenAIRE

    Mooij, Petra; Balla-Jhagjhoorsingh, Sunita S.; Koopman, Gerrit; Beenhakker, Niels; van Haaften, Patricia; Baak, Ilona; Nieuwenhuis, Ivonne G.; Kondova, Ivanela; Wagner, Ralf; Wolf, Hans; Gómez, Carmen E.; José L Nájera; Jiménez, Victoria; Esteban, Mariano; Heeney, Jonathan L.

    2008-01-01

    Poxvirus vectors have proven to be highly effective for boosting immune responses in diverse vaccine settings. Recent reports reveal marked differences in the gene expression of human dendritic cells infected with two leading poxvirus-based human immunodeficiency virus (HIV) vaccine candidates, New York vaccinia virus (NYVAC) and modified vaccinia virus Ankara (MVA). To understand how complex genomic changes in these two vaccine vectors translate into antigen-specific systemic immune response...

  12. Interfacial microstructures and solder joint strengths of the Sn-8Zn-3Bi and Sn-9Zn-lAl Pb-free solder pastes on OSP finished printed circuit boards

    International Nuclear Information System (INIS)

    Two kinds of lead-free solders, Sn-8Zn-3Bi and Sn-9Zn-lAl, were used to mount passive components onto printed circuit boards via a re-flow soldering process. The samples were stored at 150 deg. C for 200, 400, 600, 800, and 1100 h. The microstructures of the samples after aged at 150 deg. C for various times were characterized using optical microscopy (OM), scanning electron microscopy (SEM), energy dispersive spectrometry (EDS) and the analyzed of solder joint shear strengths. The joint strength between Sn-8Zn-3Bi and Cu pad was about 4.0 ± 0.3 kg, while the strength between Sn-9Zn-lAl and Cu pad had values of 2.6 ± 0.1 kg. Both kinds of solder joints exhibited reduced strengths with increasing aging times. After aging at 150 deg. C for 1100 h, the joints strengths of Sn-8Zn-3Bi and Sn-9Zn-lAl were 1.8 ± 0.3 and 1.7 ± 0.3 kg, respectively. Both the Sn-8Zn-3Bi and Sn-9Zn-lAl joints showed brittle fracture behaviors. A flat layer of Cu5Zn8 intermetallic compound (IMC) was formed between Sn-8Zn-3Bi solder and Cu pad after reflow. When the aging time was increased to 400 h, Zn-depletion and formation of Cu6Sn5 IMC were observed in the solders due to the interaction between the tin and zinc compounds. The interaction between Sn-9Zn-lAl solder and Cu pad had similar behavior, however, Cu6Sn5 IMC formed in Sn-9Zn-lAl solder when after aging at 150 deg. C for 600 h. As the aging time increased, both types of solders generated clear IMC spalling layers with large and continuous voids. Those voids substantially decreased the joint strength

  13. Interfacial microstructures and solder joint strengths of the Sn-8Zn-3Bi and Sn-9Zn-lAl Pb-free solder pastes on OSP finished printed circuit boards

    Energy Technology Data Exchange (ETDEWEB)

    Lin, C.-T. [Department of Materials Science and Engineering, National United University, 1 Lein-Da, Kung-Ching Li, Miaoli 36003, Taiwan (China); Electronics and Optoelectronics Research Laboratories, Industrial Technology Research Institute, 195 Section 4, Chung-Hsing Road, Chutung, Hsinchu 31040, Taiwan (China); Hsi, C.-S. [Department of Materials Science and Engineering, National United University, 1 Lein-Da, Kung-Ching Li, Miaoli 36003, Taiwan (China); Wang, M.-C. [Faculty of Fragrance and Cosmetics, Kaohsiung Medical University, 100 Shih-Chuan 1st Road, Kaohsiung 807, Taiwan (China)], E-mail: mcwang@kmu.edu.tw; Chang, T.-C.; Liang, M.-K. [Electronics and Optoelectronics Research Laboratories, Industrial Technology Research Institute, 195 Section 4, Chung-Hsing Road, Chutung, Hsinchu 31040, Taiwan (China)

    2008-07-14

    Two kinds of lead-free solders, Sn-8Zn-3Bi and Sn-9Zn-lAl, were used to mount passive components onto printed circuit boards via a re-flow soldering process. The samples were stored at 150 deg. C for 200, 400, 600, 800, and 1100 h. The microstructures of the samples after aged at 150 deg. C for various times were characterized using optical microscopy (OM), scanning electron microscopy (SEM), energy dispersive spectrometry (EDS) and the analyzed of solder joint shear strengths. The joint strength between Sn-8Zn-3Bi and Cu pad was about 4.0 {+-} 0.3 kg, while the strength between Sn-9Zn-lAl and Cu pad had values of 2.6 {+-} 0.1 kg. Both kinds of solder joints exhibited reduced strengths with increasing aging times. After aging at 150 deg. C for 1100 h, the joints strengths of Sn-8Zn-3Bi and Sn-9Zn-lAl were 1.8 {+-} 0.3 and 1.7 {+-} 0.3 kg, respectively. Both the Sn-8Zn-3Bi and Sn-9Zn-lAl joints showed brittle fracture behaviors. A flat layer of Cu{sub 5}Zn{sub 8} intermetallic compound (IMC) was formed between Sn-8Zn-3Bi solder and Cu pad after reflow. When the aging time was increased to 400 h, Zn-depletion and formation of Cu{sub 6}Sn{sub 5} IMC were observed in the solders due to the interaction between the tin and zinc compounds. The interaction between Sn-9Zn-lAl solder and Cu pad had similar behavior, however, Cu{sub 6}Sn{sub 5} IMC formed in Sn-9Zn-lAl solder when after aging at 150 deg. C for 600 h. As the aging time increased, both types of solders generated clear IMC spalling layers with large and continuous voids. Those voids substantially decreased the joint strength.

  14. Self-assembly of Sn-3Ag-0.5Cu Solder in Thermoplastic Resin Containing Carboxyl Group and its Interconnection

    Science.gov (United States)

    Miyauchi, Kazuhiro; Yamashita, Yukihiko; Suzuki, Naoya; Takano, Nozomu

    2014-09-01

    The self-assembly of solder powder on pads is attractive as a novel interconnection method between chips and substrates. However, the solder used in this method is limited to Sn-58Bi and Sn-52In. In contrast, Sn-3Ag-0.5Cu has been relatively less studied despite its wide use as a lead-free solder in assembling semiconductor packages. Hence, here, polymeric materials incorporating Sn-3Ag-0.5Cu solder powder were investigated for the self-assembly of the solder on pads at temperatures up to 260°C in a lead-free reflow process. The self-assembly of the solder was observed with an optical microscope through transparent glass chips placed on substrates covered with the polymeric materials incorporating the solder powder. Differential scanning calorimetry measurements were performed to confirm the behaviors of the reaction of the resins and the melting of the solder. When epoxy resin with a fluxing additive was used as a matrix, self-assembly of the solder was prevented by the cross-linking reaction. Conversely, when thermoplastic resin containing carboxyl groups was used as a matrix, the self-assembly of solder was successfully achieved in the absence of fluxing additives. The shear strength of interconnection using reflowfilm with lamination was sufficient and significantly increased during the reflow process. However, the shear strength of the reflowfilm showed cohesive failure, possibly because of the brittle intermetallic compounds (Ag3Sn, Au4Sn) network in bulk was lower than that of conventional solder paste that showed interfacial failure after the reflow process with a rapid cooling rate.

  15. Immunogenicity of a virosomally-formulated Plasmodium falciparum GLURP-MSP3 chimeric protein-based malaria vaccine candidate in comparison to adjuvanted formulations

    Directory of Open Access Journals (Sweden)

    Tamborrini Marco

    2011-12-01

    Full Text Available Abstract Background In clinical trials, immunopotentiating reconstituted influenza virosomes (IRIVs have shown great potential as a versatile antigen delivery platform for synthetic peptides derived from Plasmodium falciparum antigens. This study describes the immunogenicity of a virosomally-formulated recombinant fusion protein comprising domains of the two malaria vaccine candidate antigens MSP3 and GLURP. Methods The highly purified recombinant protein GMZ2 was coupled to phosphatidylethanolamine and the conjugates incorporated into the membrane of IRIVs. The immunogenicity of this adjuvant-free virosomal formulation was compared to GMZ2 formulated with the adjuvants Montanide ISA 720 and Alum in three mouse strains with different genetic backgrounds. Results Intramuscular injections of all three candidate vaccine formulations induced GMZ2-specific antibody responses in all mice tested. In general, the humoral immune response in outbred NMRI mice was stronger than that in inbred BALB/c and C57BL/6 mice. ELISA with the recombinant antigens demonstrated immunodominance of the GLURP component over the MSP3 component. However, compared to the Al(OH3-adjuvanted formulation the two other formulations elicited in NMRI mice a larger proportion of anti-MSP3 antibodies. Analyses of the induced GMZ2-specific IgG subclass profiles showed for all three formulations a predominance of the IgG1 isotype. Immune sera against all three formulations exhibited cross-reactivity with in vitro cultivated blood-stage parasites. Immunofluorescence and immunoblot competition experiments showed that both components of the hybrid protein induced IgG cross-reactive with the corresponding native proteins. Conclusion A virosomal formulation of the chimeric protein GMZ2 induced P. falciparum blood stage parasite cross-reactive IgG responses specific for both MSP3 and GLURP. GMZ2 thus represents a candidate component suitable for inclusion into a multi-valent virosomal

  16. Identification and Comparison of Candidate Olfactory Genes in the Olfactory and Non-Olfactory Organs of Elm Pest Ambrostoma quadriimpressum (Coleoptera: Chrysomelidae Based on Transcriptome Analysis.

    Directory of Open Access Journals (Sweden)

    Yinliang Wang

    Full Text Available The leaf beetle Ambrostoma quadriimpressum (Coleoptera: Chrysomelidae is a predominant forest pest that causes substantial damage to the lumber industry and city management. However, no effective and environmentally friendly chemical method has been discovered to control this pest. Until recently, the molecular basis of the olfactory system in A. quadriimpressum was completely unknown. In this study, antennae and leg transcriptomes were analyzed and compared using deep sequencing data to identify the olfactory genes in A. quadriimpressum. Moreover, the expression profiles of both male and female candidate olfactory genes were analyzed and validated by bioinformatics, motif analysis, homology analysis, semi-quantitative RT-PCR and RT-qPCR experiments in antennal and non-olfactory organs to explore the candidate olfactory genes that might play key roles in the life cycle of A. quadriimpressum. As a result, approximately 102.9 million and 97.3 million clean reads were obtained from the libraries created from the antennas and legs, respectively. Annotation led to 34344 Unigenes, which were matched to known proteins. Annotation data revealed that the number of genes in antenna with binding functions and receptor activity was greater than that of legs. Furthermore, many pathway genes were differentially expressed in the two organs. Sixteen candidate odorant binding proteins (OBPs, 10 chemosensory proteins (CSPs, 34 odorant receptors (ORs, 20 inotropic receptors [1] and 2 sensory neuron membrane proteins (SNMPs and their isoforms were identified. Additionally, 15 OBPs, 9 CSPs, 18 ORs, 6 IRs and 2 SNMPs were predicted to be complete ORFs. Using RT-PCR, RT-qPCR and homology analysis, AquaOBP1/2/4/7/C1/C6, AquaCSP3/9, AquaOR8/9/10/14/15/18/20/26/29/33, AquaIR8a/13/25a showed olfactory-specific expression, indicating that these genes might play a key role in olfaction-related behaviors in A. quadriimpressum such as foraging and seeking. AquaOBP4/C5, Aqua

  17. Explorative study into the sustainable use and substitution of soldering metals in electronics: ecological and economical consequences of the ban of lead in electronics and lessons to be learned for the future

    OpenAIRE

    Deubzer, O.

    2007-01-01

    The Directive 2002/95/EC (RoHS Directive), among other substances, bans the use of lead in the electrical and electronics industry. This explorative study assesses the worldwide environmental and economical effects of the substitution of lead in solders and finishes. It shows the worldwide additional cost of lead-free soldering compared to soldering with lead-containing solders and finishes. Also the additional consumption of tin, silver, bismuth and other metals, the worldwide additional ene...

  18. Influence of TiO{sub 2} nanoparticles on IMC growth in Sn–3.0Ag–0.5Cu–xTiO{sub 2} solder joints in reflow process

    Energy Technology Data Exchange (ETDEWEB)

    Tang, Y. [School of Electronic and Information Engineering, South China University of Technology, Guangzhou 510641 (China); School of Information, Zhongkai University of Agriculture and Engineering, Guangzhou 510225 (China); Li, G.Y., E-mail: phgyli@scut.edu.cn [School of Electronic and Information Engineering, South China University of Technology, Guangzhou 510641 (China); Pan, Y.C. [School of Electronic and Information Engineering, South China University of Technology, Guangzhou 510641 (China)

    2013-03-25

    Highlights: ► The microstructure and kinetics of IMC growth between SAC-xTiO{sub 2} and Cu were studied. ► Addition of small amounts TiO{sub 2} nanoparticles can suppress the growth of IMC layer. ► Nano-TiO{sub 2} addition can act as a grain refiner in the IMC formation and growth. ► The growth of the IMC layer is controlled through combined kinetics process. -- Abstract: The influence of TiO{sub 2} nanoparticles on the growth kinetics of intermetallic compound (IMC) between Sn–3.0 wt.% Ag–0.5 wt.% Cu–x wt.%TiO{sub 2} (x = 0, 0.02, 0.05, 0.1, 0.3, and 0.6) solder and copper substrate during reflow process has been investigated in this study. Scanning electron microscope (SEM) was applied to observe the microstructural evolution of the solder joints, to measure the thickness of the IMC layer, and to estimate the grain size of the IMC layer. The IMC phases were identified by energy-dispersive X-ray spectroscopy (EDX) and X-ray diffractometry (XRD). Results show that both the thickness and grain size of IMC decrease when TiO{sub 2} nanoparticles are added into the Sn–3.0Ag–0.5Cu solder system, and have a significant drop when the weight percentage of TiO{sub 2} nanoparticles is about 0.1 wt.%. Beyond this amount, the thickness and grain size of IMC increase slightly. The growth exponents for both the IMC layers and grains are determined by curve-fitting to study the growth kinetics of IMC in the soldering reaction process. Results reveal that the growth exponents of the IMC layer range from 0.354 to 0.358, and those of the IMC grains range from 0.332 to 0.346, which suggests that the growth of the IMC layer is controlled by the combined kinetics process of atomic interdiffusion, interfacial reaction, and grain ripening. These data also show that Sn–3.0Ag–0.5Cu with about 0.1 wt.% TiO{sub 2} nanoparticles solder system exhibits the smallest growth rate and gives the most prominent effect in suppressing IMC growth and refining IMC grain size. Based

  19. Investigating the thermomechanical properties and intermetallic layer formation of Bi micro-alloyed low-Ag content solders

    International Nuclear Information System (INIS)

    Highlights: • Thermomechanical properties of SnAgCu and micro-alloyed solders were investigated. • Intermetallic layer growth of SnAgCu and micro-alloyed solders was investigated. • The Cu6Sn5 intermetallic layer growth during soldering was lower in SnAgCu alloys. • The layer growth during Thermal Shock was lower in micro-alloyed solders. • The SnAg0.3Cu0.7Bi0.1Sb0.01 alloy has the best thermomechanical properties. - Abstract: In our research, we performed comparative analyses concerning various lead-free SAC (Sn96.5Ag3Cu0.5, Sn95.5Ag4Cu0.5) and two types of micro-alloyed SAC (SnAgCu + Bi + Sb) solder alloys. The mechanical properties of these solder alloys were characterised by measuring the shear strength of 0603 (1.5 × 0.75 mm) size chip resistors’ joints. We designed a testboard, which contains fifty pieces of 0603 size resistors for mechanical characterisation and for measuring the thickness of intermetallic layers. During the experiment, twenty-eight pieces of testboards were soldered with vapour phase soldering (seven with each solder alloy) and sixteen of them were subjected to Thermal-Shock (TS) life-time tests with temperature range of +140 to −40 °C up to 2000 cycles. The intermetallic layer (IML) formation was investigated with Scanning Electron Microscopy (SEM) and Scanning Transmission Electron Microscopy (STEM) methods; and the growth of the layer was analysed by measuring the IML thickness on cross-sectional samples after given TS cycles. It is shown that the thickness of the intermetallic layer in as-reflowed samples (samples without aging) depends on the silver content of the given alloy. Besides, the layer growth rate during Thermal Shock tests is affected by the number of intermetallic layer grain-boundaries along a unit of length

  20. Investigating the thermomechanical properties and intermetallic layer formation of Bi micro-alloyed low-Ag content solders

    Energy Technology Data Exchange (ETDEWEB)

    Krammer, Olivér, E-mail: krammer@ett.bme.hu [Department of Electronics Technology, Budapest University of Technology and Economics, Egry J. u. 18., Budapest H-1111 (Hungary); Garami, Tamás [Department of Electronics Technology, Budapest University of Technology and Economics, Egry J. u. 18., Budapest H-1111 (Hungary); Horváth, Barbara [National Institute for Materials Science, 1-2-1 Sengen, Tsukuba 305-0047 (Japan); Hurtony, Tamás; Medgyes, Bálint; Jakab, László [Department of Electronics Technology, Budapest University of Technology and Economics, Egry J. u. 18., Budapest H-1111 (Hungary)

    2015-06-15

    Highlights: • Thermomechanical properties of SnAgCu and micro-alloyed solders were investigated. • Intermetallic layer growth of SnAgCu and micro-alloyed solders was investigated. • The Cu{sub 6}Sn{sub 5} intermetallic layer growth during soldering was lower in SnAgCu alloys. • The layer growth during Thermal Shock was lower in micro-alloyed solders. • The SnAg0.3Cu0.7Bi0.1Sb0.01 alloy has the best thermomechanical properties. - Abstract: In our research, we performed comparative analyses concerning various lead-free SAC (Sn96.5Ag3Cu0.5, Sn95.5Ag4Cu0.5) and two types of micro-alloyed SAC (SnAgCu + Bi + Sb) solder alloys. The mechanical properties of these solder alloys were characterised by measuring the shear strength of 0603 (1.5 × 0.75 mm) size chip resistors’ joints. We designed a testboard, which contains fifty pieces of 0603 size resistors for mechanical characterisation and for measuring the thickness of intermetallic layers. During the experiment, twenty-eight pieces of testboards were soldered with vapour phase soldering (seven with each solder alloy) and sixteen of them were subjected to Thermal-Shock (TS) life-time tests with temperature range of +140 to −40 °C up to 2000 cycles. The intermetallic layer (IML) formation was investigated with Scanning Electron Microscopy (SEM) and Scanning Transmission Electron Microscopy (STEM) methods; and the growth of the layer was analysed by measuring the IML thickness on cross-sectional samples after given TS cycles. It is shown that the thickness of the intermetallic layer in as-reflowed samples (samples without aging) depends on the silver content of the given alloy. Besides, the layer growth rate during Thermal Shock tests is affected by the number of intermetallic layer grain-boundaries along a unit of length.

  1. Electromigration and thermomigration in lead-free tin-silver-copper and eutectic tin-lead flip chip solder joints

    Science.gov (United States)

    Ou Yang, Fan-Yi

    Phase separation and microstructure change of eutectic SnPb and SnAgCu flip chip solder joint were investigated under thermomigration, electromigration, stressmigration and the combination of these effects. Different morphological behaviors under DC and AC electromigration were seen. Phase separation with Pb rich phase migration to the anode was observed when current density is below 1.6 x 104 A/cm2 at 100°C. For some cases, phase separation of Pb-rich phase and Su-rich phase as well as refinement of lamellar microstructure has also been observed. We propose that the refinement is due to recrystallization. On the other hand, time-dependent melting of eutectic SnPb flip chip solder joints has been observed to occur frequently with current density above 1.6 x 104 A/cm 2at 100°C. It has been found that it is due to joule heating of the on-chip Al interconnects. We found that electromigration has especially generated voids at the anode of the Al. This damage has greatly increased the resistance of the Al, which produces the heat needed to melt the solder joint. Owing to the line-to-bump configuration in flip chip solder joints, current crowding occurs when electrons enters into or exits from the solder bump. At the cathode contact, current crowding induced pancake-type void formation was observed widely. Furthermore, at the anode contact, we note that hillock or whisker forms. The cross-sectioned surface in SnPb showed dimple and bulge after electromigration, while that of SnAgCu remained flat. The difference is due to a larger back stress in the SnAgCu, consequently electromigration in SnAgCu is slower than that in SnPb. For thermomigration in eutectic SnPb flip chip solder joints, phase separation of Sn and Pb occurred, with Pb moving to the cold end. Both Sn and Pb have a stepwise concentration profile across solder bump. Refinement of lamellar microstructure was observed, indicating recrystallization. Also, thermomigration in eutectic SnAgCu flip chip solder

  2. EVOLUTION OF MICROSTRUCTURE OF Sn-Ag-Cu LEAD-FREE FLIP CHIP SOLDER JOINTS DURING AGING PROCESS

    Institute of Scientific and Technical Information of China (English)

    Y.H. Tian; C.Q. Wang; W.F. Zhou

    2006-01-01

    Flip chip bonding has become a primary technology that has found application in the chip interconnection process in the electronic manufacturing industry in recent years. The solder joints of the flip chip bonding are small and consist of complicated microstructures such as Sn solution,eutectic mixture, and intermetallic compounds (IMCs), whose mechanical performance is quite different from the original solder bulk. The evolution of microstructure of the flip chip solder joints under thermal aging was analyzed. The results show that with an increase in aging time, coarsening of solder bulk matrix and AuSn4 IMCs occurred within the solder. The IMCs that are formed at the bottom side of the flip chip bond were different from those on the top side during the aging process. ( Cu, Ni, Au )6Sn5 were formed at the interfaces of both sides, and large complicated (Au, Ni,Cu)Sn4 IMCs appeared for some time near the bottom interface after aging, but they disappeared again and thus ( Cu, Ni,Au )6Sns IMC thickness increased considerably. The influence of reflow times during the flip chip bonding (as-bonded condition) on the characteristics of interfacial IMCs was weakened when subjected to the aging process.

  3. Comparative Study of ENIG and ENEPIG as Surface Finishes for a Sn-Ag-Cu Solder Joint

    Science.gov (United States)

    Yoon, Jeong-Won; Noh, Bo-In; Jung, Seung-Boo

    2011-09-01

    Interfacial reactions and joint reliability of Sn-3.0Ag-0.5Cu solder with two different surface finishes, electroless nickel-immersion gold (ENIG) and electroless nickel-electroless palladium-immersion gold (ENEPIG), were evaluated during a reflow process. We first compared the interfacial reactions of the two solder joints and also successfully revealed a connection between the interfacial reaction behavior and mechanical reliability. The Sn-Ag-Cu/ENIG joint exhibited a higher intermetallic compound (IMC) growth rate and a higher consumption rate of the Ni(P) layer than the Sn-Ag-Cu/ENEPIG joint. The presence of the Pd layer in the ENEPIG suppressed the growth of the interfacial IMC layer and the consumption of the Ni(P) layer, resulting in the superior interfacial stability of the solder joint. The shear test results show that the ENIG joint fractured along the interface, exhibiting indications of brittle failure possibly due to the brittle IMC layer. In contrast, the failure of the ENEPIG joint only went through the bulk solder, supporting the idea that the interface is mechanically reliable. The results from this study confirm that the Sn-Ag-Cu/ENEPIG solder joint is mechanically robust and, thus, the combination is a viable option for a Pb-free package system.

  4. Three Dimensional Characterization of Tin Crystallography and Cu6Sn5 Intermetallics in Solder Joints by Multiscale Tomography

    Science.gov (United States)

    Kirubanandham, A.; Lujan-Regalado, I.; Vallabhaneni, R.; Chawla, N.

    2016-07-01

    Decreasing pitch size in electronic packaging has resulted in a drastic decrease in solder volumes. The Sn grain crystallography and fraction of intermetallic compounds (IMCs) in small-scale solder joints evolve much differently at the smaller length scales. A cross-sectional study limits the morphological analysis of microstructural features to two dimensions. This study utilizes serial sectioning technique in conjunction with electron backscatter diffraction to investigate the crystallographic orientation of both Sn grains and Cu6Sn5 IMCs in Cu/Pure Sn/Cu solder joints in three dimensional (3D). Quantification of grain aspect ratio is affected by local cooling rate differences within the solder volume. Backscatter electron imaging and focused ion beam serial sectioning enabled the visualization of morphology of both nanosized Cu6Sn5 IMCs and the hollow hexagonal morphology type Cu6Sn5 IMCs in 3D. Quantification and visualization of microstructural features in 3D thus enable us to better understand the microstructure and deformation mechanics within these small scale solder joints.

  5. A novel dengue virus serotype 1 vaccine candidate based on Japanese encephalitis virus vaccine strain SA14-14-2 as the backbone.

    Science.gov (United States)

    Yang, Huiqiang; Li, Zhushi; Lin, Hua; Wang, Wei; Yang, Jian; Liu, Lina; Zeng, Xianwu; Wu, Yonglin; Yu, Yongxin; Li, Yuhua

    2016-06-01

    To develop a potential dengue vaccine candidate, a full-length cDNA clone of a novel chimeric virus was constructed using recombinant DNA technology, with Japanese encephalitis virus (JEV) vaccine strain SA14-14-2 as the backbone, with its premembrane (prM) and envelope (E) genes substituted by their counterparts from dengue virus type 1 (DENV1). The chimeric virus (JEV/DENV1) was successfully recovered from primary hamster kidney (PHK) cells by transfection with the in vitro transcription products of JEV/DENV1 cDNA and was identified by complete genome sequencing and immunofluorescent staining. No neuroinvasiveness of this chimeric virus was observed in mice inoculated by the subcutaneous route (s.c.) or by the intraperitoneal route (i.p.), while some neurovirulence was displayed in mice that were inoculated directly by the intracerebral route (i.c.). The chimeric virus was able to stimulate high-titer production of antibodies against DENV1 and provided protection against lethal challenge with neuroadapted dengue virus in mice. These results suggest that the chimeric virus is a promising dengue vaccine candidate. PMID:26976137

  6. Various Approaches for Targeting Quasar Candidates

    Science.gov (United States)

    Zhang, Y.; Zhao, Y.

    2015-09-01

    With the establishment and development of space-based and ground-based observational facilities, the improvement of scientific output of high-cost facilities is still a hot issue for astronomers. The discovery of new and rare quasars attracts much attention. Different methods to select quasar candidates are in bloom. Among them, some are based on color cuts, some are from multiwavelength data, some rely on variability of quasars, some are based on data mining, and some depend on ensemble methods.

  7. Stability of molybdenum nanoparticles in Sn-3.8Ag-0.7Cu solder during multiple reflow and their influence on interfacial intermetallic compounds

    Energy Technology Data Exchange (ETDEWEB)

    Haseeb, A.S.M.A., E-mail: haseeb@um.edu.my; Arafat, M.M., E-mail: arafat_mahmood@yahoo.com; Johan, Mohd Rafie, E-mail: mrafiej@um.edu.my

    2012-02-15

    This work investigates the effects of molybdenum nanoparticles on the growth of interfacial intermetallic compound between Sn-3.8Ag-0.7Cu solder and copper substrate during multiple reflow. Molybdenum nanoparticles were mixed with Sn-3.8Ag-0.7Cu solder paste by manual mixing. Solder samples were reflowed on a copper substrate in a 250 Degree-Sign C reflow oven up to six times. The molybdenum content of the bulk solder was determined by inductive coupled plasma-optical emission spectrometry. It is found that upon the addition of molybdenum nanoparticles to Sn-3.8Ag-0.7Cu solder, the interfacial intermetallic compound thickness and scallop diameter decreases under all reflow conditions. Molybdenum nanoparticles do not appear to dissolve or react with the solder. They tend to adsorb preferentially at the interface between solder and the intermetallic compound scallops. It is suggested that molybdenum nanoparticles impart their influence on the interfacial intermetallic compound as discrete particles. The intact, discrete nanoparticles, by absorbing preferentially at the interface, hinder the diffusion flux of the substrate and thereby suppress the intermetallic compound growth. - Highlights: Black-Right-Pointing-Pointer Mo nanoparticles do not dissolve or react with the SAC solder during reflow. Black-Right-Pointing-Pointer Addition of Mo nanoparticles results smaller IMC thickness and scallop diameter. Black-Right-Pointing-Pointer Mo nanoparticles influence the interfacial IMC through discrete particle effect.

  8. Effects of fullerenes reinforcement on the performance of 96.5Sn–3Ag–0.5Cu lead-free solder

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Guang [State Key Laboratory of Materials Processing and Die & Mould Technology, Huazhong University of Science and Technology, Wuhan 430074 (China); Wolfson School of Mechanical and Manufacturing Engineering, Loughborough University (United Kingdom); Wu, Fengshun, E-mail: fengshunwu@hust.edu.cn [State Key Laboratory of Materials Processing and Die & Mould Technology, Huazhong University of Science and Technology, Wuhan 430074 (China); Liu, Changqing [Wolfson School of Mechanical and Manufacturing Engineering, Loughborough University (United Kingdom); Xia, Weisheng; Liu, Hui [State Key Laboratory of Materials Processing and Die & Mould Technology, Huazhong University of Science and Technology, Wuhan 430074 (China)

    2015-06-11

    In this study, fullerenes (FNSs) nanoparticles with different weight fractions (0.05, 0.1 and 0.2 wt%) were successfully integrated into SAC305 lead-free solder utilizing a powder metallurgy route. The composite solders were then studied extensively concerning their microstructures, wettability, thermal and mechanical properties. Refined microstructures were observed in the matrices of the composite solders after the addition of FNSs nanoparticles to the solder alloy. With an increase in the amount of FNSs nanoparticles added, the composite solders exhibited a homologous improvement in wettability. Furthermore, the electrical resistance and melting point of the solder changed only marginally after the addition of the FNSs nanoparticles. According to the mechanical results, the 0.2 wt% FNSs addition would give rise to a 12.1% and 19.9% improvement in shear strength and microhardness respectively in comparison to the unreinforced solders. These progressions can be attributed to the refined microstructures and the presence of uniformly dispersed FNSs nanoparticles, which acted as reinforcements. Finally, the existence of added FNSs nanoparticles in the solder matrix was further confirmed by energy-dispersive X-ray spectroscopy, scanning electron microscopy, and Raman spectroscopy.

  9. Effects of fullerenes reinforcement on the performance of 96.5Sn–3Ag–0.5Cu lead-free solder

    International Nuclear Information System (INIS)

    In this study, fullerenes (FNSs) nanoparticles with different weight fractions (0.05, 0.1 and 0.2 wt%) were successfully integrated into SAC305 lead-free solder utilizing a powder metallurgy route. The composite solders were then studied extensively concerning their microstructures, wettability, thermal and mechanical properties. Refined microstructures were observed in the matrices of the composite solders after the addition of FNSs nanoparticles to the solder alloy. With an increase in the amount of FNSs nanoparticles added, the composite solders exhibited a homologous improvement in wettability. Furthermore, the electrical resistance and melting point of the solder changed only marginally after the addition of the FNSs nanoparticles. According to the mechanical results, the 0.2 wt% FNSs addition would give rise to a 12.1% and 19.9% improvement in shear strength and microhardness respectively in comparison to the unreinforced solders. These progressions can be attributed to the refined microstructures and the presence of uniformly dispersed FNSs nanoparticles, which acted as reinforcements. Finally, the existence of added FNSs nanoparticles in the solder matrix was further confirmed by energy-dispersive X-ray spectroscopy, scanning electron microscopy, and Raman spectroscopy

  10. Influence of High- G Mechanical Shock and Thermal Cycling on Localized Recrystallization in Sn-Ag-Cu Solder Interconnects

    Science.gov (United States)

    Lee, Tae-Kyu; Kim, Choong-Un; Bieler, Thomas R.

    2014-01-01

    The impact of isothermal aging and recrystallized grain structure distribution on mechanical shock and thermal cycling performance of solder joints with 1% and 3% silver content Sn-Ag-Cu interconnects were investigated. Localized recrystallized grain structure distributions were analyzed to identify correlations between the microstructure evolution and shock performance. The results reveal that the shock tolerance depends on the amount of shock energy that can be absorbed during each shock cycle, which depends on microstructural features. Based on the recrystallized grain distribution, additional isothermal aging in 1% silver Sn-Ag-Cu interconnects shows improved shock performance, whereas degraded shock performance was observed in 3% Sn-Ag-Cu interconnects. Using the same grain boundary distribution analysis on thermally cycled samples, relationships between the particle size distribution, localized recrystallized grain structure development, shock, and thermomechanical performance were identified: finer particle spacing is beneficial for thermal cycling as it resists grain boundary generation, while conversely, wider particle spacing facilitates recrystallization and grain boundary mobility that allows Sn to absorb shock energy.

  11. Effect of additives on the co-electrodeposition of Sn-Ag-Cu lead-free solder composition

    International Nuclear Information System (INIS)

    We have developed a methane sulfonic acid (MSA) based ternary electrodeposition bath for the deposition of near eutectic Sn-Ag-Cu films aimed at solder bumping applications in electronics. The bath contains thiourea as chelating agent and iso-octyl phenoxy ethanol (OPPE) as surfactant. We added gelatin to this bath and studied its effect on bath stability, microstructure of the deposited films and the film composition. It is found that the bath containing both the additives, viz. OPPE and gelatin, show improved stability up to 8-10 days. Striking improvement in the film microstructure, in terms of the compactness, uniformity and refinement of grains was found when the bath contained these additives. Detailed electrochemical studies with the help of cyclic voltametry and impedance analysis helped in understanding the role played by these additives during deposition. It is confirmed that there is a formation of loosely connected, highly non-uniform passivating film on the cathode surface, which is removed competitively by the depositing metal ions during the deposition. It is also clear that the additives play a role in the formation of such a passivating film.

  12. Correlation between microstructure and hardness of a Bi-1.5wt%Ag lead-free solder alloy

    Science.gov (United States)

    Spinelli, J. E.; Macedo, R. A.; Silva, B. L.; Garcia, A.

    2016-03-01

    In the present study a hypoeutectic Bi-1.5wt%Ag alloy was directionally solidified under transient heat flow conditions and the microstructure was analysed. Bi-Ag alloys are considered as potential alternatives to replace Pb-based alloys as solder materials for metallic connections under high temperatures. However, a lack of understanding regarding the effects of solidification thermal parameters (growth rate - VL, the cooling rate - Ṫ) on microstructural aspects is reported in literature. Another challenge is to improve properties and reliability. The results of the present study include the determination of the tip growth rate and the cooling rate by cooling curves recorded by thermocouples positioned along the casting length, metallography, X-ray fluorescence (XRF) and Vickers hardness. The entire directionally solidified Bi-1.5Ag microstructure was arranged by faceted Bi-rich dendrites surrounded by a eutectic mixture (Bi+Ag). The primary and secondary dendrite arm spacing (λ1 and λ2), the interphase spacing (λ) and the diameter of Ag-rich particles were also measured along the casting length; and experimental growth laws. Relating these microstructural features to the experimental thermal parameters are proposed.

  13. Protective effects of a Modified Vaccinia Ankara-based vaccine candidate against Crimean-Congo Haemorrhagic Fever virus require both cellular and humoral responses

    Science.gov (United States)

    Dowall, Stuart D.; Graham, Victoria A.; Rayner, Emma; Hunter, Laura; Watson, Robert; Taylor, Irene; Rule, Antony; Carroll, Miles W.; Hewson, Roger

    2016-01-01

    Crimean-Congo Haemorrhagic Fever (CCHF) is a severe tick-borne disease, endemic in many countries in Africa, the Middle East, Eastern Europe and Asia. There is no approved vaccine currently available against CCHF. The most promising candidate, which has previously been shown to confer protection in the small animal model, is a modified Vaccinia Ankara virus vector expressing the CCHF viral glycoprotein (MVA-GP). It has been shown that MVA-GP induces both humoral and cellular immunogenicity. In the present study, sera and T-lymphocytes were passively and adoptively transferred into recipient mice prior to challenge with CCHF virus. Results demonstrated that mediators from both arms of the immune system were required to demonstrate protective effects against lethal challenge. PMID:27272940

  14. A 2015 International Geomagnetic Reference Field (IGRF) candidate model based on Swarm’s experimental absolute magnetometer vector mode data

    DEFF Research Database (Denmark)

    Vigneron, Pierre; Hulot, Gauthier; Olsen, Nils;

    2015-01-01

    Each of the three satellites of the European Space Agency Swarm mission carries an absolute scalar magnetometer (ASM) that provides the nominal 1-Hz scalar data of the mission for both science and calibration purposes. These ASM instruments, however, also deliver autonomous 1-Hz experimental vector...... data. Here, we report on how ASM-only scalar and vector data from the Alpha and Bravo satellites between November 29, 2013 (a week after launch) and September 25, 2014 (for on-time delivery of the model on October 1, 2014) could be used to build a very valuable candidate model for the 2015.......0 International Geomagnetic Reference Field (IGRF). A parent model was first computed, describing the geomagnetic field of internal origin up to degree and order 40 in a spherical harmonic representation and including a constant secular variation up to degree and order 8. This model was next simply forwarded to...

  15. Protective effects of a Modified Vaccinia Ankara-based vaccine candidate against Crimean-Congo Haemorrhagic Fever virus require both cellular and humoral responses.

    Directory of Open Access Journals (Sweden)

    Stuart D Dowall

    Full Text Available Crimean-Congo Haemorrhagic Fever (CCHF is a severe tick-borne disease, endemic in many countries in Africa, the Middle East, Eastern Europe and Asia. There is no approved vaccine currently available against CCHF. The most promising candidate, which has previously been shown to confer protection in the small animal model, is a modified Vaccinia Ankara virus vector expressing the CCHF viral glycoprotein (MVA-GP. It has been shown that MVA-GP induces both humoral and cellular immunogenicity. In the present study, sera and T-lymphocytes were passively and adoptively transferred into recipient mice prior to challenge with CCHF virus. Results demonstrated that mediators from both arms of the immune system were required to demonstrate protective effects against lethal challenge.

  16. Effect of Yttrium on the Fracture Strength of the Sn-1.0Ag-0.5Cu Solder Joints

    Science.gov (United States)

    Choi, Hyelim; Kaplan, Wayne D.; Choe, Heeman

    2016-04-01

    This is a preliminary investigation on the mechanical properties of Pb-free Sn-1.0Ag-0.5Cu solder joints containing 0.02 wt.% to 0.1 wt.% Y under a range of thermal aging and reflow conditions. Despite the significantly thicker intermetallic compound (IMC) formed at the solder joint, the 0.1 wt.% Y-doped joint exhibited a higher fracture strength than its baseline Sn-1.0Ag-0.5Cu counterpart under most aging and reflow conditions. This may be associated with the formation of Y-Cu IMCs formed at the interface between the solder and the Cu substrate, because the Y-Cu IMCs have recently been referred to as relatively `ductile' IMCs.

  17. Retarding the electromigration effects to the eutectic SnBi solder joints by micro-sized Ni-particles reinforcement approach

    International Nuclear Information System (INIS)

    Research highlights: → We used a revised solder joints with one-dimension geometry that can help us to investigate the true failure mechanisms of solder joints induced by EM. → One of possible solutions to inhibit the EM effect to solder joint can be achieved by adding micro- or nano-sized metal particles into it. → Micro-sized Ni particles were selected as the reinforcement to retard the phase segregation in the eutectic SnBi solder joints under high current density (104 A/cm2). It has been approved in this study that Ni particles can act as obstacles to obstruct the fast diffusion channel along the phase boundaries in the eutectic SnBi system. - Abstract: Electromigration (EM) has become one of the reliability concerns to the electronic solder joint due to its increasing capacity to bear the high current density (104 A/cm2). Although the failure induced by EM can trigger a large void across the entire cathode interface, no effective solutions are presented throughout years of effort on this problem. Here, the composite solder joints are addressed to demonstrate their potential roles on solving the EM issue in the eutectic SnBi solder joints. Micro-sized Ni particles were selected to intentionally add into the solder matrix due to their extensive application as a barrier layer in the under-bump-metallization (UBM) of flip chip solder joints. The ultimate results illustrated that the Ni particles can react with Sn to form the cluster-type Sn-Ni intermetallic compounds (IMCs) inside the solder matrix after the first reflow. Accordingly, the phase segregation of Sn and Bi was significantly inhibited during the current stressing, demonstrating the Sn-Ni IMCs can act as the obstacles to obstruct the movement of dominant diffusion entity (Bi atoms/ions) along the phase boundaries.

  18. Interconnection of thermal parameters, microstructure and mechanical properties in directionally solidified Sn–Sb lead-free solder alloys

    Energy Technology Data Exchange (ETDEWEB)

    Dias, Marcelino; Costa, Thiago [Department of Manufacturing and Materials Engineering, University of Campinas — UNICAMP, 13083-860 Campinas, SP (Brazil); Rocha, Otávio [Federal Institute of Education, Science and Technology of Pará — IFPA, 66093-020 Belém, PA (Brazil); Spinelli, José E. [Department of Materials Engineering, Federal University of São Carlos — UFSCar, 13565-905 São Carlos, SP (Brazil); Cheung, Noé, E-mail: cheung@fem.unicamp.br [Department of Manufacturing and Materials Engineering, University of Campinas — UNICAMP, 13083-860 Campinas, SP (Brazil); Garcia, Amauri [Department of Manufacturing and Materials Engineering, University of Campinas — UNICAMP, 13083-860 Campinas, SP (Brazil)

    2015-08-15

    Considerable effort is being made to develop lead-free solders for assembling in environmental-conscious electronics, due to the inherent toxicity of Pb. The search for substitute alloys of Pb–Sn solders has increased in order to comply with different soldering purposes. The solder must not only meet the expected levels of electrical performance but may also have appropriate mechanical strength, with the absence of cracks in the solder joints. The Sn–Sb alloy system has a range of compositions that can be potentially included in the class of high temperature solders. This study aims to establish interrelations of solidification thermal parameters, microstructure and mechanical properties of Sn–Sb alloys (2 wt.%Sb and 5.5 wt.%Sb) samples, which were directionally solidified under cooling rates similar to those of reflow procedures in industrial practice. A complete high-cooling rate cellular growth is shown to be associated with the Sn–2.0 wt.%Sb alloy and a reverse dendrite-to-cell transition is observed for the Sn–5.5 wt.%Sb alloy. Strength and ductility of the Sn–2.0 wt.%Sb alloy are shown not to be affected by the cellular spacing. On the other hand, a considerable variation in these properties is associated with the cellular region of the Sn–5.5 wt.%Sb alloy casting. - Graphical abstract: Display Omitted - Highlights: • The microstructure of the Sn–2 wt.%Sb alloy is characterized by high-cooling rates cells. • Reverse dendrite > cell transition occurs for Sn–5.5 wt.%Sb alloy: cells prevail for cooling rates > 1.2 K/s. • Sn–5.5 wt.%Sb alloy: the dendritic region occurs for cooling rates < 0.9 K/s. • Sn–5.5 wt.%Sb alloy: tensile properties are improved with decreasing cellular spacing.

  19. Interconnection of thermal parameters, microstructure and mechanical properties in directionally solidified Sn–Sb lead-free solder alloys

    International Nuclear Information System (INIS)

    Considerable effort is being made to develop lead-free solders for assembling in environmental-conscious electronics, due to the inherent toxicity of Pb. The search for substitute alloys of Pb–Sn solders has increased in order to comply with different soldering purposes. The solder must not only meet the expected levels of electrical performance but may also have appropriate mechanical strength, with the absence of cracks in the solder joints. The Sn–Sb alloy system has a range of compositions that can be potentially included in the class of high temperature solders. This study aims to establish interrelations of solidification thermal parameters, microstructure and mechanical properties of Sn–Sb alloys (2 wt.%Sb and 5.5 wt.%Sb) samples, which were directionally solidified under cooling rates similar to those of reflow procedures in industrial practice. A complete high-cooling rate cellular growth is shown to be associated with the Sn–2.0 wt.%Sb alloy and a reverse dendrite-to-cell transition is observed for the Sn–5.5 wt.%Sb alloy. Strength and ductility of the Sn–2.0 wt.%Sb alloy are shown not to be affected by the cellular spacing. On the other hand, a considerable variation in these properties is associated with the cellular region of the Sn–5.5 wt.%Sb alloy casting. - Graphical abstract: Display Omitted - Highlights: • The microstructure of the Sn–2 wt.%Sb alloy is characterized by high-cooling rates cells. • Reverse dendrite > cell transition occurs for Sn–5.5 wt.%Sb alloy: cells prevail for cooling rates > 1.2 K/s. • Sn–5.5 wt.%Sb alloy: the dendritic region occurs for cooling rates < 0.9 K/s. • Sn–5.5 wt.%Sb alloy: tensile properties are improved with decreasing cellular spacing

  20. A New Solder Jet Printing Technology and its Characteristics%一种新型焊膏喷印技术

    Institute of Scientific and Technical Information of China (English)

    周峻霖; 臧子昂; 卢剑寒; 李金宝; 段元明

    2012-01-01

      Solder paste printing is one of key processing technologies in SMT/Surface Mount Technology manufacture, the processing quality would impact the following surface mounting, solder-reflow and packaging, the comprehensive product quality,etc. At first,the paper introduced the solder paste screen printing technology, and a brand-new solder paste jet printing technology developed from abroad. Later, it focused on a comparison of the processing principles, characteristics and advantages of these 2 processing technologies. The present microelectronics Industry are mostly applying metal mask stencil in solder paste screen printing to push for high-quality solder pattern, but due to impacts from multi-factors like equipment parameters, operator experiencee, the screen printing quality would be effected. Comparatively speaking, the jet printing technology is highly automatic and it is capable of shortening the difference of solder patten processing qulity against the original solder pattern expectation in jet software.%  焊膏印刷是SMT/表面组装技术的核心工艺,其加工质量的优劣关系到后序组装、回流焊、封装及产品整体性能。文章首先介绍了通过金属箔掩模版、激光打孔不锈钢掩模版进行焊膏丝印的技术,并介绍了国外研发成功的一种焊膏喷印新技术。同时,对两种工艺技术的原理、特点和优势进行了详细比较。当前微电子业界焊膏网印过程中,一般大量使用丝网印刷来获取高质量的焊膏图形,但多种硬件参数、操作员个人经验因素等综合因素会影响到最终加工效果。比较而言,焊膏喷印方式自动化程度高,可有效缩短焊膏图形最终加工结果与焊膏喷印软件中预计效果间的差距。