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D P Hampshire - One of the best experts on this subject based on the ideXlab platform.
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Soldered Joints an essential component of demountable high temperature superconducting fusion magnets
Superconductor Science and Technology, 2016Co-Authors: Yeekin Tsui, E Surrey, D P HampshireAbstract: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.
Yeekin Tsui - One of the best experts on this subject based on the ideXlab platform.
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Soldered Joints an essential component of demountable high temperature superconducting fusion magnets
Superconductor Science and Technology, 2016Co-Authors: Yeekin Tsui, E Surrey, D P HampshireAbstract: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.
Song-bai Xue - One of the best experts on this subject based on the ideXlab platform.
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Reliability study of lead-free solders under specific conditions
Journal of Materials Science: Materials in Electronics, 2015Co-Authors: Shuang Liu, Song-bai XueAbstract:Currently, accompanying the development of microelectronic joining and packaging, the integrated level of integrated circuit among the electronic devices has been substantially improved, which means the number of the Soldered Joints on a device is becoming more and more while the size of the micro-joint turns to be smaller and smaller. Given that Soldered Joints do play an important role in electronic packaging, serving as both mechanical bridges and electrical interconnections between the components and the bonding pads, to investigate the sensitivity of reliability of lead-free solders to various severe conditions deserves considerable concerns. This paper introduces the recent reliability research of lead-free solders under several specific conditions (e.g., isothermal aging, corrosive environment, drop impact, radiation) comprehensively, producing a fundamental summarization for the further reliability research.
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tensile strength of fine pitch qfp lead free Soldered Joints with diode laser soldering
Soldering & Surface Mount Technology, 2011Co-Authors: Peng Xue, Song-bai Xue, Liang Zhang, Lili Gao, Zong Jie Han, Yifu Shen, Hong Zhu, Yan ChenAbstract:Purpose – The purpose of this paper is to investigate the laser soldering of fine pitch quad flat package (QFP) devices using lead‐free solders and solder joint reliability during thermal cycling.Design/methodology/approach – QFP devices were selected as the test vehicles and were Soldered with four alloy types, Sn37Pb, Sn3.5Ag, Sn3.8Ag0.7Cu and Sn3.8Ag0.7Cu0.03Ce. The experimental samples were QFP‐256 devices with lead‐free solder paste on the printed circuit boards. The packages were dried for 24 h at 125°C prior to reflow soldering. Soldering experiments on the QFP devices were carried out with an infrared (IR) reflow soldering oven and a diode laser (DL) soldering system. Reflow soldering was performed at peak temperatures of 210°C (SnPb), 240°C (SnAgCu and SnAgCuCe) and 250°C (SnAg), as determined on the boards. Pull testing was adopted to evaluate the tensile strength of the four solders using an STR–1000 micro‐joint strength tester.Findings – The tensile force of the QFP micro‐Joints increased as l...
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effects of bulk cu6sn5 intermetallic compounds on the properties of sn ag cu ce Soldered Joints
Soldering & Surface Mount Technology, 2011Co-Authors: Liang Zhang, Song-bai Xue, Lili Gao, Zhong Sheng, Wei Dai, Yan ChenAbstract:Purpose – The purpose of this paper is to explore the formation and growth mechanism of bulk Cu6Sn5 intermetallic compounds, selecting Sn‐Ag‐Cu‐Ce solders as specimens.Design/methodology/approach – In order to further enhance the properties of SnAgCu solder, trace amount of rare earth Ce was selected as alloying addition into the alloy; in previous investigations, the enhancements include better wettability, physical properties, creep strength and tensile strength. In this paper, the microstructure of Sn‐Ag‐Cu‐Ce Soldered Joints and its interfacial intermetallic compounds were investigated. Moreover, different morphologies of Cu6Sn5 IMCs were enumerated and described, and Ostwald ripening theory was employed to interpret the formation mechanism of bulk Cu6Sn5 IMCs.Findings – In addition, based on finite element simulation, it is found that the von Mises stress concentrate around the bulk Cu6Sn5 IMCs inside the Sn‐Ag‐Cu‐Ce Soldered Joints after three thermal cycling loading (−55‐125°C). From the stress dis...
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reliability study of sn ag cu ce Soldered Joints in quad flat packages
Microelectronics Reliability, 2010Co-Authors: Liang Zhang, Song-bai Xue, Yan Chen, Lili Gao, Zhong Sheng, Wei Dai, Zeng GuangAbstract:Abstract The reliability of Sn–Ag–Cu–Ce lead-free Soldered Joints in quad flat packages under thermal cycling was investigated based on finite element simulation and experiments. The stress and strain response of fine pitch QFP device lead-free Soldered Joints were analyzed using finite element method based on Garofalo–Arrhenius model. The simulated results indicate that the creep distribution is not uniform, the heel of Joints is the maximum creep strain concentrated sites. And comparisons were then made with experimental results of the cracks observed in the Sn–Ag–Cu–Ce Soldered Joints subjected to the temperature cycled experiment. In addition, the relative mechanical and metallurgical factors, which dominate the failure of Soldered Joints, were utilized to analyze the phenomena. The fracture surfaces indicate that crack initiate and propagate along the interface among bulk Cu 6 Sn 5 phases in Sn–Ag–Cu–Ce Soldered Joints.
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reliability studies of sn 9zn cu and sn 9zn 0 3ag cu Soldered Joints with aging treatment
Journal of Materials Science: Materials in Electronics, 2010Co-Authors: Wen Xue Chen, Song-bai Xue, Hui WangAbstract:In this study, the interfacial reactions and joint reliabilities of Sn–9Zn/Cu and Sn–9Zn–0.3Ag/Cu were investigated during isothermal aging at 150 °C for aging times of up to 1,000 h. Cu5Zn8 IMCs layer is formed at the as-Soldered Sn–9Zn/Cu interface. Adding 0.3wt.% Ag results in the adsorption of AgZn3 on the Cu5Zn8 IMCs layer. The as-Soldered Sn–9Zn/Cu and Sn–9Zn–0.3Ag/Cu Joints have sufficient pull strength. The thickness of the IMCs layer formed at the interface of Sn–9Zn/Cu and Sn–9Zn–0.3Ag/Cu both increase with increasing aging time. Correspondingly, both the pull forces of the Sn–9Zn and Sn–9Zn–0.3Ag Soldered Joints gradually decrease as the aging time prolonged. However, the thickness of the IMCs layer of Sn–9Zn–0.3Ag/Cu increases much slower than that of Sn–9Zn/Cu and the pull force of Sn–9Zn–0.3Ag Soldered joint decreases much slower than that of Sn–9Zn Soldered joint. After aging for 1,000 h, some Cu–Sn IMCs form between the Cu5Zn8 IMC and the Cu substrate, many voids form at the interface between the Cu5Zn8 layer and solder alloy, and some cracks form in the Cu5Zn8 IMCs layer of Sn–9Zn/Cu. The pull force Sn–9Zn Soldered joint decreases by 53.1% compared to the pull force measured after as-Soldered. Fracture of Sn–9Zn/Cu occurred on the IMCs layer on the whole and the fracture micrograph implies a brittle fracture. While the pull force of Sn–9Zn–0.3Ag Soldered joint decreases by 51.7% after aging at 150 °C for 1,000 h. The fracture mode of Sn–9Zn–0.3Ag Soldered joint is partially brittle at the IMCs layer, and partially ductile at the outer ring of the solder.
Yan Chen - One of the best experts on this subject based on the ideXlab platform.
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tensile strength of fine pitch qfp lead free Soldered Joints with diode laser soldering
Soldering & Surface Mount Technology, 2011Co-Authors: Peng Xue, Song-bai Xue, Liang Zhang, Lili Gao, Zong Jie Han, Yifu Shen, Hong Zhu, Yan ChenAbstract:Purpose – The purpose of this paper is to investigate the laser soldering of fine pitch quad flat package (QFP) devices using lead‐free solders and solder joint reliability during thermal cycling.Design/methodology/approach – QFP devices were selected as the test vehicles and were Soldered with four alloy types, Sn37Pb, Sn3.5Ag, Sn3.8Ag0.7Cu and Sn3.8Ag0.7Cu0.03Ce. The experimental samples were QFP‐256 devices with lead‐free solder paste on the printed circuit boards. The packages were dried for 24 h at 125°C prior to reflow soldering. Soldering experiments on the QFP devices were carried out with an infrared (IR) reflow soldering oven and a diode laser (DL) soldering system. Reflow soldering was performed at peak temperatures of 210°C (SnPb), 240°C (SnAgCu and SnAgCuCe) and 250°C (SnAg), as determined on the boards. Pull testing was adopted to evaluate the tensile strength of the four solders using an STR–1000 micro‐joint strength tester.Findings – The tensile force of the QFP micro‐Joints increased as l...
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effects of bulk cu6sn5 intermetallic compounds on the properties of sn ag cu ce Soldered Joints
Soldering & Surface Mount Technology, 2011Co-Authors: Liang Zhang, Song-bai Xue, Lili Gao, Zhong Sheng, Wei Dai, Yan ChenAbstract:Purpose – The purpose of this paper is to explore the formation and growth mechanism of bulk Cu6Sn5 intermetallic compounds, selecting Sn‐Ag‐Cu‐Ce solders as specimens.Design/methodology/approach – In order to further enhance the properties of SnAgCu solder, trace amount of rare earth Ce was selected as alloying addition into the alloy; in previous investigations, the enhancements include better wettability, physical properties, creep strength and tensile strength. In this paper, the microstructure of Sn‐Ag‐Cu‐Ce Soldered Joints and its interfacial intermetallic compounds were investigated. Moreover, different morphologies of Cu6Sn5 IMCs were enumerated and described, and Ostwald ripening theory was employed to interpret the formation mechanism of bulk Cu6Sn5 IMCs.Findings – In addition, based on finite element simulation, it is found that the von Mises stress concentrate around the bulk Cu6Sn5 IMCs inside the Sn‐Ag‐Cu‐Ce Soldered Joints after three thermal cycling loading (−55‐125°C). From the stress dis...
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reliability study of sn ag cu ce Soldered Joints in quad flat packages
Microelectronics Reliability, 2010Co-Authors: Liang Zhang, Song-bai Xue, Yan Chen, Lili Gao, Zhong Sheng, Wei Dai, Zeng GuangAbstract:Abstract The reliability of Sn–Ag–Cu–Ce lead-free Soldered Joints in quad flat packages under thermal cycling was investigated based on finite element simulation and experiments. The stress and strain response of fine pitch QFP device lead-free Soldered Joints were analyzed using finite element method based on Garofalo–Arrhenius model. The simulated results indicate that the creep distribution is not uniform, the heel of Joints is the maximum creep strain concentrated sites. And comparisons were then made with experimental results of the cracks observed in the Sn–Ag–Cu–Ce Soldered Joints subjected to the temperature cycled experiment. In addition, the relative mechanical and metallurgical factors, which dominate the failure of Soldered Joints, were utilized to analyze the phenomena. The fracture surfaces indicate that crack initiate and propagate along the interface among bulk Cu 6 Sn 5 phases in Sn–Ag–Cu–Ce Soldered Joints.
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properties of snagcu snagcuce Soldered Joints for electronic packaging
Journal of Materials Science: Materials in Electronics, 2010Co-Authors: Liang Zhang, Song-bai Xue, Lili Gao, Zhong Sheng, Guang Zeng, Yan ChenAbstract:For quad flat packages (QFP256), lead-free Soldered Joints reliability in service is a critical issue. In this paper, soldering experiments of quad flat package (QFP256) devices were carried out by means of infrared reflow soldering system with Sn–3.8Ag–0.7Cu and Sn–3.8Ag–0.7Cu–0.03Ce lead-free solders, respectively, and the mechanical properties of micro-Joints of the QFP devices were tested and studied by STR micro-Joints tester. The results indicate that the tensile strength of Sn–Ag–Cu–Ce Soldered Joints is better than that of Sn–Ag–Cu Soldered Joints. In particular, the addition of trace Ce to the Sn–Ag–Cu solder can refine the microstructures and decrease the thickness of the intermetallic compound layer of Sn–Ag–Cu solder alloys. In addition, the stress–strain response of Sn–Ag–Cu/Sn–Ag–Cu–Ce Soldered Joints in quad flat packaging was investigated using finite element method based on Garofalo–Arrhenius model. The simulated results indicate creep distribution of Soldered Joints is not uniform, the heel and toe of Soldered Joints, the area between Soldered Joints and leads are the creep concentrated sites. The creep strain of Sn–Ag–Cu–Ce Soldered Joints is lower than that of Sn–Ag–Cu Soldered Joints.
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Properties of SnAgCu/SnAgCuCe Soldered Joints for electronic packaging
Journal of Materials Science: Materials in Electronics, 2009Co-Authors: Liang Zhang, Song-bai Xue, Lili Gao, Zhong Sheng, Guang Zeng, Yan ChenAbstract:For quad flat packages (QFP256), lead-free Soldered Joints reliability in service is a critical issue. In this paper, soldering experiments of quad flat package (QFP256) devices were carried out by means of infrared reflow soldering system with Sn–3.8Ag–0.7Cu and Sn–3.8Ag–0.7Cu–0.03Ce lead-free solders, respectively, and the mechanical properties of micro-Joints of the QFP devices were tested and studied by STR micro-Joints tester. The results indicate that the tensile strength of Sn–Ag–Cu–Ce Soldered Joints is better than that of Sn–Ag–Cu Soldered Joints. In particular, the addition of trace Ce to the Sn–Ag–Cu solder can refine the microstructures and decrease the thickness of the intermetallic compound layer of Sn–Ag–Cu solder alloys. In addition, the stress–strain response of Sn–Ag–Cu/Sn–Ag–Cu–Ce Soldered Joints in quad flat packaging was investigated using finite element method based on Garofalo–Arrhenius model. The simulated results indicate creep distribution of Soldered Joints is not uniform, the heel and toe of Soldered Joints, the area between Soldered Joints and leads are the creep concentrated sites. The creep strain of Sn–Ag–Cu–Ce Soldered Joints is lower than that of Sn–Ag–Cu Soldered Joints.
E Surrey - One of the best experts on this subject based on the ideXlab platform.
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Soldered Joints an essential component of demountable high temperature superconducting fusion magnets
Superconductor Science and Technology, 2016Co-Authors: Yeekin Tsui, E Surrey, D P HampshireAbstract: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.