A Method Based on a Crack Propagation Model for Predicting Solder Fatigue Life

We previously developed a crack propagation model that can be used to calculate crack paths in micro-solder joints in semiconductor structures. We have now developed a method based on this model that can be used to predict solder fatigue life. Correcting for the effect of element size is difficult when fatigue life is calculated using a finite element method, so we investigated the dependence of the calculated life on the element size and developed a formula for approximating this dependence using Hutchinson-Rice-Rosengren singularity theory. This formula enables us to estimate fatigue life regardless of element size. We tested this formula by analyzing the effect of element size on the fatigue life of a center-cracked plate (CCP) made of tin-lead eutectic solder. The results agreed well with the experimental results, indicating that our method can effectively predict solder fatigue life.