UCPD Model for Pb Free Solder

Abstract

A unified creep plasticity damage (UCPD) model for eutectic SnPb and Pbfree solders was developed and implemented into finite element analysis codes. The new model will be described along with the relationship between the model's damage evolution equation and an empirical Coffin–Manson relationship for solder fatigue. Next, developments needed to model crack initiation and growth in solder joints will be described. Finally, experimentally observed cracks in typical solder joints subjected to thermal mechanical fatigue are compared with model predictions. Finite element based modeling is particularly suited for predicting solder joint fatigue of advanced electronics packaging, e.g. packageonpackage (PoP), because it allows for evaluation of a variety of package materials and geometries.