Purpose This study aims to understand the phenomenon of stress relaxation in the gate pin of press-pack IGBT devices due to the coupling effect of electrical, thermal and mechanical fields, gate pin stress relaxation life model based on multiphysics field simulation and the Arrhenius equation is established. Taking the press-pack IGBT single-chip device as the research object, the stress distribution of the gate pin of the press-pack device is analyzed through simulation. The stress relaxation experiment of the gate pin establishes the thimble stress relaxation life models under different temperatures, and the power cycling experiments of the press-pack device verify the accuracy of the life model. Design/methodology/approach First, the COMSOL simulation is used to establish a multiphysics field model of the press-pack IGBT device to simulate the internal stress distribution characteristics of the device. Second, the stress relaxation formula of gate pin is established through constant-temperature experiments to quantify cumulative fatigue damage, and gate pin stress relaxation life model is built based on the Arrhenius equation. Finally, power cycling experiments are conducted to obtain the variation law of the electrical and thermal characteristic parameters of the device during the stress relaxation process of gate pin and verify the accuracy of gate pin life model. Findings Through multiphysics field simulation and stress relaxation experiments, it is found that the load loss rate of gate pin has a linear relationship with the logarithm of time, and the stress relaxation rate of the gate thimble varies significantly under different temperatures. Gate pin shows cumulative fatigue damage; the case temperature of the thimble and the corresponding junction temperature of the chip both increase with the same trend in the power cycling experiment. By monitoring the case temperature of pin, the time when the load loss rate of the thimble decays to the threshold can be estimated in real time. Originality/value Through multiphysics field simulation and experimental verification, this study proposes a stress relaxation mechanism of the gate pin under the multiphysics field coupling effect in press-pack IGBT devices, as well as its impact on device reliability.
Wang et al. (Mon,) studied this question.