Bond-Wire Layout Optimization in Power Modules Through Simulation of Electro-Thermo-Mechanical Migration Flux Under Power Cycling

The lifetime of power modules is affected by degradation of the emitter connection and die-attach material. Increasing requirements on power modules e.g., higher power density, requires better understanding of module design, driving forces of degradation and loading conditions. The present study introduces a Finite Element model for design optimization considering electric currents, thermal gradients and stress gradients as driving forces for materials degradation. The optimal design is determined by the migration flux at the chip-wire interface under Power Cycling. A lifetime relation is introduced to compare the migration flux simulation with empirical lifetime models. Four bond-wire layouts are presented based on the optimization model and the impact of design parameters such as bond-wire loop height, bond-wire foot pattern and number of wires is highlighted.