A computational damage mechanics model for thermomigration

Miniaturization of electronics to nanoscale leads to significantly higher current density levels and larger thermal gradients in electronics packaging. Laboratory test data show that thermomigration plays a significant role in high current density induced failure in solder joints and interconnects. In this paper, a computational damage mechanics model for thermomigration process is proposed and implemented in finite element method. This model is based on thermodynamics and formulated by continuum mechanics equations, mass transport principals and heat transfer equations. A damage evolution model using entropy production rate as a metric is utilized to evaluate the degradation in solder joints subjected to high temperature gradients.