Calculation and Analysis of Influence Factors of Electrical Contact Resistances Inside Press-pack IGBT Device

Electrical contact resistances of the press-pack insulated gate bipolar transistor (IGBT) device directly affect electro-thermal distribution characteristics and operational reliability of the device. However, the existing contact resistance calculation methods rely on the semi-empirical model or the built-in model of the finite element software and fail to consider the influence of surface topography parameters. The electrical contact resistances cannot be calculated accurately. An electrical contact resistance model and influence laws of the press-pack IGBT device considering the influence of material surface morphology parameters and contact pressure were proposed. Firstly, a mathematical model of electrical contact resistance that takes into account material resistivity, contact pressure, roughness and microhardness parameters was established based on the electrical contact theory. Secondly, the parameters of the electrical contact resistance model were selected by analyzing the surface characteristics of the material. A finite element simulation model of a single-chip press-pack IGBT device was established. The contact pressure and electrical contact resistances of the device were calculated. The validity of the proposed model was indirectly verified by measuring the on-resistance of the device. Finally, the effects of contact pressure, chip resistivity and surface roughness on the electrical contact resistances were analyzed. The results show that the proposed electrical contact resistance model can accurately characterize the electrical contact resistances of the device compared with the built-in model of COMSOL software. The electrical contact resistances between the chip and the upper and lower molybdenum in the press-pack IGBT device are the largest. When the pressure is small, the electrical contact resistances change significantly due to the resistivity, roughness and pressure. © 2021 Chin. Soc. for Elec. Eng.