Thermal Resistance Analysis of Power MOSFETs using Creo/ANSYS Software Versus Physical Measurements

Abstract

High requirement of power electronic converters in power density makes heat dissipation issue critical caused by the packaging of power electronic devices and modules. Compared with the wire bond process, the clip bond process shows excellent thermal performance, which is widely used in the packaging of power MOSFETs. However, due to the complicated structure of the copper bridge in the clip bond process, the thermal resistance cannot be easily evaluated according to mathematical models. A generic method is proposed to evaluate the thermal resistance of power MOSFETs, which is verified by a PDFN5×6 plastic-packaged power MOSFET. According to the physical structure of the selected MOSFET, the finite element model is established using combined Creo and ANSYS software. The thermal resistance from the PN junction to the case and the one from the junction to the PCB board can be accurately simulated from the developed model. The simulation results show very small errors compared with the physical measurements based on the JESD51 standard. The proposed method can replace the thermal resistance test to some extent, which can save time and cost in the early stage of the design and development of power electronic devices and modules.