Impact of the UBM geometry and solder bump shape on electromigration reliability in a package system

This paper proposes a parametric simulation plan for UBM geometry with different UBM rim angles, diameters and thicknesses. The parameter plan for the solder bump with different heights and diameters, and different shapes is also investigated. The goal of this study is to understand the impact of the die shrinkage on solder joint reliability under electromigration failure, and to optimize the UBM and solder bump shapes to reduce the damage of electromigration. A multiple physics finite element method for electromigration which considers the atomic density gradient is presented to conduct the simulation.