A Finite-Element-Based Methodology for Evaluating Solder Electromigration Current Limits of Sn/Pb Eutectic Solder Bumps

This paper investigates the effect of current distribution to the bump and current crowding on the electromigration (EM) of Sn/Pb eutectic solder bumps. The peak current density in the bump is found to have a significant effect on the EM lifetime of the tested structures and, thus, impacts the maximum allowable bump current. A finite-element model is developed which accurately predicts the maximum allowable bump current as a function of the current crowding. This model makes it possible to predict the maximum bump current for a new current-distribution scheme based on results from EM tests on an existing current- distribution scheme.