摘要
采用高精度微拉伸试验和有限元数值模拟方法研究不同微尺度的Sn-Ag-Cu无铅钎料模拟互连焊点力学行为和性能演变的尺寸效应。结果表明,当焊点高度恒定(225μm)而焊点直径逐渐减小(475～200μm)时,拉伸断裂强度显著提高且远高于体钎料的抗拉强度,断裂应变也逐渐增加;焊点的断裂位置及模式由较大直径时的界面低延性断裂转变为小直径时焊点中间部位的大变形颈缩断裂。模拟结果表明,由于焊点内力学拘束水平的不同,小直径焊点的界面应力较低且最大应力分布在焊点中间部分,易导致断裂发生在焊点中部,接头强度应较高;而大直径焊点中最大应力处于焊点界面,易导致界面金属间化合物层在较低外加应力下起裂,焊点断裂强度应较低。
The size effect of mechanical behaviors and performance evolution of micro-scale interconnects prepared by lead-free Sn-Ag-Cu solder with different joint sizes are investigated by a sophisticated micro-tension experiment and finite element simulation. The results show that the tensile strength and fracture strain of the joints increase with decreasing joint diameter （475-200μm） while keeping joint thickness constant （225μm）, and strength values of the joints are obviously higher than that of the bulk solder. For the joints with large diameter, the fracture occurs in interfaces of the joints and shows low ductility, in contrast to necking type fracture with large deformation happened in the mid of the joints having small diameter. Numerical simulation results show that due to the different levels of mechanical constraint in the solder joints, the small diameter joint has relatively low interface stresses and the maximum stress locates in the mid of the joint where the final fracture usually occurs, thus the joint would exhibit high fracture strength; while for the large diameter joint, the maximum stress locates in the interfaces where cracks easily initiate and grow in intermetallic compound layer through the interfaces at a low level of applied stress, and consequently the strength of the joint will below.
出处
《机械工程学报》
EI
CAS
CSCD
北大核心
2010年第2期55-60,共6页
Journal of Mechanical Engineering
基金
教育部首批'新世纪优秀人才'基金资助项目(NCET-04-0824)
关键词
无铅钎料
微互连焊点
力学性能
尺寸效应
有限元模拟
Lead-flee solder Micro-interconnect joints Mechanical properties Size effects Finite element simulation
