热循环加载条件下SMT焊点应力应变过程的有限元分析

ＳＭＴ焊 热循环条件下的应力应变过程分析是ＳＭＴ焊点可靠性的重要方向。本文采用粘弹塑性材料模式描述ＳｎＰｂ钎料的力学本构响应，对非城堡型ＬＣＣＣ焊蹼结构进行三维有限元分析，考察焊点在热循环加载过程中的应力应变等力学行为。研究结果表明，焊点钎料内的高应力发生在热循环的低温阶段，升降温过程中的蠕变和非弹性应变的累积显著，蠕变应变在非弹性应变中占主导地位，应力应变滞后环在热循环的最初几个周期内就能很快稳

FEM Analysis of Stress/Strain Processin SMT Solder Joint Under Thermal Cycle

FEM analysis of stress/strain process in SMT solder joint under thermal cycle is one of the important aspects in the research field of soldered joints reliability.In this paper,visco-elastic-plastic constitutive model was described for the behavior of SnPb solder,and the three dimcnsional soldered joints structurc for non-castle typed LCCC was analyzed whth finite elenent method to investigate the mechanical behavior such as stress/strain process under thermal cycle.The results show the maximum stress took place at lowest temperature and hardly decreased with temperature ramp,the accumulated creep and inelastic strain increased distinctly with temperature ramp and down ,the creep strain dominated the inelastic strain ,the stress/strain hysteresis loop was stabilized quickly by first several thermal cycles .The results of experimental test,in which the specimen was similar to the FEM model,showed that the site with maximum stress/stram agreed with the crack initiation and propagation path of soldered joints in experiments.