Optimization on Thermomechanical Behavior for Improving the Reliability of Press Pack IGBT Using Response Surface Method

A press pack insulated gate bipolar transistor (PP IGBT) device consists of multiple materials. Under the influence of alternating current and clamping force, the device suffers from complex thermomechanical stress. However, the experience-based packaging design does not consider the coupling effect of junction temperature fluctuation (
$\Delta T_{\mathrm{ j}}$
) and mechanical stress, which may not ensure the optimal thermomechanical behavior and cause the advance failure of the PP IGBT device. Thus, it is significant to provide a theoretical basis and select appropriate parameters for device packaging design. In this article, a finite-element model of a 3300-V/50-A PP IGBT device is first built and verified via experiments. The influence of principal parameters on the thermomechanical behavior is then illustrated. Next, the response surface method is proposed to reveal the significance level of each parameter. According to simulation results under different combinations of parameters, quadratic response surfaces are obtained. The combined effects of packaging parameters on
$\Delta T_{\mathrm{ j}}$
and stress are clarified. Finally, optimal results are derived and verified. An approximate 4 °C decrease in
$\Delta T_{\mathrm{ j}}$
and a 19.8% decrease in stress are achieved simultaneously in the long-time power cycling test. A 2.6 °C reduction in junction temperature is achieved under the practical high-voltage direct current (HVDC) condition.