Creep behaviors of Pb-free solder joints during current stressing

Electromigration and creep as two of the most important reliability issues gain much attention, and flurry of academic activities dedicate to understand fundamental physics of them. However, since real solder joints are usually exposure to complicated conditions with high current density, temperature excursion, and mechanical loading, when analyzing creep of a real solder joint, Electromigration must be taken into account because of the interaction between them. In this study, simple shear to failure was performed at different temperature and stress level to evaluate failure behavior of solder joints. Activation energy and stress exponent under high current density were also calculated and discussed. This research indicated that, strain rate was accelerated by high current density at different levels of stress and temperature. The effect of high current density played more important roles at low stress and low temperature condition. At high stress and high temperature, the accelerating effect was not that significance. When high current density was introduced, both activation energy and stress exponent tend to decrease.