Insulation State Assessment of Press-Pack IGBTs Based on Electric and Temperature Field Simulation

IGBT devices are used throughout the entire process of integrating renewable energy generation into the grid, AC/DC transmission, and grid establishment, serving as foundational components supporting the development of smart grids. However, during prolonged operation, issues such as encapsulation insulation may arise in IGBT devices. Therefore, it is necessary to investigate the electric field and temperature distribution within the internal packaging insulation structure of press-pack IGBTs. Whether the IGBT is in the off-state or on-state processes under electrostatic field conditions, simulation results from steady-state calculations indicate that the highest electric field primarily occurs at the junction of the polyamide (PI) passivation layer/air gap/aluminum plating. Additionally, under continuous current conditions, the temperature of the chip's active region is significantly higher than that of the two end electrodes, with the highest temperature occurring near the PI passivation layer. The increase in temperature-induced thermal expansion causes changes in parameters such as roughness between materials, leading to an increase in contact thermal resistance, further raising the temperature. Both high temperature and high electric field may potentially cause failure in PI, which serves as the packaging insulation material. In the long run, this can pose a threat to the chip's packaging insulation and accelerate the device's aging process.