An Improved Thermal Coupling Network Model Considering Thermal Interface Material Aging of IGBT Modules

Insulated gate bipolar transistor (IGBT) modules typically employ the thermal grease between the baseplate and the heat sink to promote the heat dissipation efficiency, also known as thermal interface material (TIM). However, TIM aging significantly increases its thermal resistance, reducing module’s thermal efficiency and elevating the junction temperature, yet the traditional thermal network model (traditional model) cannot characterize this phenomenon. Herein, an improved model is proposed to account for TIM aging, enhancing the accuracy of the junction temperature by analyzing the heat transfer angle and the path. The influence of aging of thermal grease on the transfer coupling area, self-thermal, and coupled thermal impedance is researched deeply, and a thermal impedance matrix is constructed. The proposed model enables effective computation of both self-thermal and coupled thermal impedances and shows remarkable improvements in thermal modeling accuracy.