An empirical model for thermal interface materials based on experimental characterizations under realistic conditions

Thermal interface materials (TIMs) contribute to a considerable part of thermal resistance from junction to ambient in power modules, which is an important design variable affecting the thermal loading and reliability performance. Nevertheless, the existing standard characterization methods for TIMs may not represent the realistic conditions in power module applications. Physical thermal models for TIMs are of high complexity, which is not always convenient enough to apply in engineering design. This paper proposes an empirical model for TIMs based on physical understandings and experimental characterizations under more realistic conditions. The proposed model includes two variables only, the initial thickness and screw torque. It retains the advantages in terms of accuracy and convenience in use. A realistic power electronic converter based experimental platform has been built and comprehensive experimental results have been conducted on a 1200 V/50 A IGBT module.