Thermal modeling of integrated power electronic modules by a lumped-parameter circuit approach

With the continuous volume reduction of the devices and power modules having the same power conditioning capability, it becomes more and more important to manage the increase of the junction temperature due to the increase of the specific power dissipations. Therefore, in order to ensure the working conditions of the devices to remain within the allowed thresholds, it is useful to model and predict the junction temperature. For a power device that consists of only one die it is easy to develop a thermal model because the die is in stand-alone condition and it does not receive the thermal effects of other dies. In the case of integrated power electronic module (IPEM), because of the presence of more than one die, it is necessary to take into account also the cross-heating effects due to the heat generation in the others dies. This work aims at describing a methodology useful to provide an equivalent thermal model, by a previously performed finite element method (FEM) analysis and simulations. The thermal model consists of an electrical circuit that takes into account both the self-heating and cross-heating effects in the prediction of the junction temperatures. Comparisons have been performed and the achieved results by the FEM simulations and SPICE-like ones show that are in good agreement.