Thermal Characterization of Multichip Power Module

As a recognized stressor of power semiconductors modules, thermal concerns are one of the major issues related to these devices, and the raise of power density of these modules increases this fact. This makes thermal models to gain in relevance, with higher accuracy and complexity requirements, in order to be able to foresee thermal failures. This article analyzes the thermal behaviour of a multichip power module, considering the heating of the devices and the influence of power losses on the integrated Negative Temperature Coefficient (NTC) thermistor. A complete thermal model considering all the chips in the module is proposed, including the thermal cross-coupling between devices. This is completed with a dynamic model to asses the temperature variations in the NTC based on the losses generated in each device. This way, an estimation principle is proposed for the online detection of abnormal behaviours inside the module.