Warpage modeling and characterization of intelligent power modules (IPMs)

Intelligent power modules (IPMs) are widely used in the electric vehicle (and hybrid electric vehicle industry nowadays due to their high power density and ability to integrate multiple components within a single package. However, the reliability of IPMs is severely degraded by the substrate warpage effect produced during the packaging process. This study therefore develops a computational model to analyze the warpage of the IPM assembly at various stages of the packaging process. The validity of the simulation model is confirmed by comparing the numerical results for the warpage of the direct plated copper substrate with the experimental observations. Taguchi experiments are then performed to examine the effects of eight control factors on the IPM package warpage following the post-mold cure (PMC) process, namely (1) the dam bar layout, (2) the epoxy molding compound (EMC) thickness, (3) the lead frame thickness, (4) the ceramic thickness, (5) the bottom layer Cu foil thickness, (6) the top layer Cu foil thickness, (7) the ceramic material type and (8) the EMC material type. Finally, the Taguchi analysis results are used to determine the optimal packaging design that minimizes the warpage of the post-PMC package.