UCLA

We have employed high resolution synchrotron radiation x-rays 3D imaging techniques, to study the electromigration (EM) failure mechanism in flip-chip solder joints. In these studies, the ex-situ imaging of the early-stage damage evolution at the interface between under bump metallurgy (UBM) layer and solder balls, revealed that the EM induced failure mode of solder joints could be described by Johnson-Mehl-Avrami (JMA) kinetics model. Thus, the JMA kinetics is proposed to serve as a new physical model for life-time prediction of Pb-free solder joints in EM tests. A corresponding Monte Carlo simulation is developed to investigate this simplified failure model and the dependence of the scale parameter and shape parameter in the statistical Weibull equation on the physical factors of the EM tests is studied.