Thermal Contact Resistance Optimization of Press-Pack IGBT Device Based on Liquid Metal Thermal Interface Material

Thermal contact resistances usually account for more than 50% of the total thermal resistance in press-pack insulated gate bipolar transistor (PP-IGBT) device, which affect the heat dissipation of the PP-IGBT device and lead to a high junction temperature. In this paper, a method for optimizing the thermal contact resistances of PP-IGBT device is proposed by filling the liquid metal thermal interface materials in the contact surface. Bismuth-based liquid metal with high thermal conductivity and electrical conductivity is chosen, and the material is used for filling between the IGBT chip and the molybdenum layers. The thermal characteristics are compared with traditional commercial PP-IGBT device using finite-element simulation and experiment methods. The high voltage insulation reliability of the proposed optimized method is verified by blocking voltage test and the long-term reliability of the device is verified by a power cycling test. The results show that the junction-to-case thermal resistance of the optimized PP-IGBT device can be reduced by more than 30%, which is helpful for improving the thermal reliability of large-capacity PP-IGBT devices.