Stochastic simulation of electromigration failure of flip chip solder bumps

Stochastic simulations are performed for the first time to explore the natu re of electromigration failure of SnPb flip chip solder bumps at room tempe rature. Treating the SnPb flip chip solder bump as a random resistor networ k and electromigration as a diffusion-controlled depletion-accumulation pro cess, the main features of limited experimental observations are well repro duced. The microstructure and current density dependence-of the time to fai lure, the median time to failure and the dynamics of void/hillock growth, a s well as the electromigration-induced resistance fluctuations are obtained to provide a comprehensive interpretation of electromigration process and failure in terms of physical parameters in SnPb solder bumps. The approach introduced in the present work can be used for elucidating the most importa nt factors in controlling the electromigration and its rate of flip chip so lder bumps, and thus contribute to their optimal design. (C) 2000 Elsevier Science Ltd. All rights reserved.