A 3-D thermal network model for the temperature monitoring of thermal grease as interface material

In the cooling system of insulated gate bipolar transistor (IGBT) module, the reliability of thermal grease is of crucial importance in the heat dissipation of IGBT module. In order to study the influence of thermal grease, thermal interface material (TIM) between IGBT module and heat sink, on the junction temperature of IGBT module under long-term load profiles, a 3-D thermal network based on thermal grease temperature monitoring is proposed. Firstly, the finite element method (FEM) simulation model of IGBT module using thermal grease as TIM is established. Then, considering thermal coupling effect, the temperature distribution of thermal grease is obtained and the temperature monitoring points of thermal grease are determined in FEM simulation. Finally, a 3-D thermal network is established to monitor the temperature in all regions of thermal grease. The influence of thermal grease degradation on the junction temperature of IGBT module is analyzed and the temperature distribution of thermal grease under long-term load profiles is obtained. The proposed 3-D thermal network model based on the temperature monitoring of thermal grease can increase the accuracy of IGBT module reliability analysis.