• CN:11-2187/TH
  • ISSN:0577-6686

机械工程学报 ›› 2022, Vol. 58 ›› Issue (2): 307-320.doi: 10.3901/JME.2022.02.307

• 微纳连接界面与可靠性 • 上一篇    

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电-热-力耦合载荷下非均匀组织Cu/Sn-58Bi/Cu微焊点拉伸力学性能研究

李望云1,2, 李兴民1, 汪健1, 梁泾洋1, 秦红波1,2   

  1. 1. 桂林电子科技大学机电工程学院 桂林 541004;
    2. 桂林电子科技大学广西制造系统与先进制造技术重点实验室 桂林 541004
  • 收稿日期:2021-04-29 修回日期:2021-07-19 出版日期:2022-01-20 发布日期:2022-03-19
  • 通讯作者: 秦红波(通信作者),男,1986年出生,博士,博士后,特聘教授,硕士研究生导师。主要研究方向为电子元器件与微纳结构可靠性、电子封装材料、焊接材料与工程。E-mail:qinhb@guet.edu.cn
  • 作者简介:李望云,男,1989年出生,博士,副研究员,硕士研究生导师。主要研究方向为微电子封装材料与可靠性、严酷环境下材料服役性能与构件力学可靠性、电子封装结构设计。E-mail:li.wangyun@guet.edu.cn
  • 基金资助:
    国家自然科学基金(51805103,52065015)、广西自然科学基金(2018GXNSFBA281065,2018GXNSFAA281222)、广西科技基地和人才专项(AD18281021,AD18281022)、广西制造系统与先进制造技术重点实验室主任基金(19-050-44-003Z)和2021年广西研究生教育创新计划(YCSW2021184)资助项目。

Tensile Performance of Inhomogeneous Microscale Cu/Sn-58Bi/Cu Solder Joints under Electro-thermo-mechanical Coupled Loads

LI Wangyun1,2, LI Xingmin1, WANG Jian1, LIANG Jingyang1, QIN Hongbo1,2   

  1. 1. School of Mechanical and Electrical Engineering, Guilin University of Electronic Technology, Guilin 541004;
    2. Guangxi Key Laboratory of Manufacturing System and Advanced Manufacturing Technology, Guilin University of Electronic Technology, Guilin 541004
  • Received:2021-04-29 Revised:2021-07-19 Online:2022-01-20 Published:2022-03-19

摘要: 电子封装微焊点往往在电、热、力等多种载荷共同作用下服役,且具有鲜明的组织不均匀特征。研究电-热-力耦合载荷下电流密度和温度对电子封装组织不均匀线型Cu/Sn-58Bi/Cu微焊点拉伸力学性能及其尺寸效应的影响。结果表明,较低温度和较低电流密度情况下,随焊点高度降低,Cu基底对钎料的力学约束增强,焊点拉伸强度提高,断裂发生在钎料体内,呈韧性断裂,与室温无电流情况下的力学行为和断裂模式一致。钎料内Sn相与Bi相电流密度非均匀分布所致的局部电流拥挤现象使两相间的温度梯度明显增加,因此由热膨胀系数差异所致的相界面应变失配和界面应力增大,致使焊点强度低于室温无电流加载时的值。随着温度和电流密度升高,Sn相与Bi相界面及钎料与IMC层界面的应变失配和界面应力加剧,导致焊点拉伸强度进一步下降;同时,断裂位置从钎料基体内逐渐转移至钎料/IMC层界面处,断裂模式由韧性断裂转为韧-脆混合断裂。

关键词: 组织不均匀微焊点, 电-热-力耦合载荷, 拉伸力学性能

Abstract: The microscale solder joint in electronic packaging usually serves under the coupled loading of electric current, heat and mechanical stress, which has a distinct inhomogeneous microstructure. Tensile performance of inhomogeneous microscale line-type Cu/Sn-58Bi/Cu solder joints with different current densities and temperatures as well as their size effects are investigated under electro-thermo-mechanical coupled loads. The results show that at low current densities and temperatures, as the height of solder joints decreases, the mechanical constraint of Cu substrate on solder increases, which enhances tensile performance of solder joints; the fracture occurs in solder matrix, showing a ductile fracture mode. These are consistent with the mechanical performance and fracture behaviour of solder joints under tensile load without electric current stressing at room temperature. The local current crowding caused by the non-uniform distribution of current densities in Sn and Bi phases increases the temperature gradient between them. The mismatch strain and stress at the Sn/Bi interface increase due to the difference in coefficient of thermal expansion between Sn and Bi. Therefore, the tensile strength of solder joints under electro-thermo-mechanical coupled loads is lower than that at room temperature without electric current stressing. As the current density and temperature increase, the mismatch strain and stress at the Sn/Bi interface and the solder/IMC layer interface increase, resulting in further decrease in tensile strength of solder joints. Moreover, the fracture location gradually changes from the solder matrix to the solder/IMC layer interface, while the fracture mode shifts from ductile fracture to ductile-brittle mixed fracture.

Key words: inhomogeneous microscale solder joint, electro-thermo-mechanical coupled loads, tensile performance

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