Analysis for thermal contact resistance of Press-Pack IGBTs

Press-pack insulated gate bipolar transistors (IGBT) have a multilayer structure, which is clamped by pressure. The IGBT chip generates heat and forms the temperature gradient in the multilayer structure during work. Due to different coefficient of thermal expansion of multilayer structure, temperature and clamping force will lead constant changes in the internal stress of the device, resulting in interface wear and roughness. The thermal contact resistance and the heat dissipation will be affected. And then reduce the reliability of the device. In this paper, the finite element Analysis (FEA) is used to analyze the heat transfer in a three-dimension model of PP IGBT. Based on the contact surface of the chip and the emitter molybdenum plate, the submodel technology is used to investigate the effects of several factors on the thermal contact resistance, including real contact areas, the height of contact joint, and the position of the third-level submodel. And then, the method of single factor analysis is used to analyze the effect on thermal contact resistance. The results show that the thermal contact resistance decrease with the increase of real contact areas, the thermal contact resistance increase with the increase of the height of the contact joint, and the position of the third-level submodel have little effect on thermal contact resistance.