ＳＭＴ焊点在热循环条件下的应力应变过程分析是ＳＭＴ焊点可靠性研究的重要方向。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焊点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定，采用与有限元分析模型相似的焊点热循环试验的结果表明，有限元的高应力应变区域与实际焊点的裂纹起裂位置和扩展路径相吻合 Stress-strain process analysis of SMT solder joints under thermal cycling is an important direction for SMT solder joint reliability research. In this paper, the viscoelasto-plastic material model is used to describe the mechanical constitutive response of SnPb solder. The three-dimensional finite element analysis of the non-cast LCCC solder joint structure is carried out to investigate the mechanical behavior of the solder joint during thermal cycling. The results show that the high stress in the solder joint occurs in the low temperature stage of the thermal cycle, and the cumulative creep and inelastic strain in the process of ascending and descending temperature are significant. The creep strain dominates the inelastic strain and the stress-strain hysteresis The ring can be quickly stabilized during the first few cycles of the thermal cycle. The results of the thermal cycling test of the solder joint, similar to the finite element analysis model, show that the crack initiation location and the crack tip location of the high stress- Expansion path match