Computational fluid dynamic and heat transfer analysis of an Al/SiC IGBT power hybrid package

Abstract

This paper describes the fluid dynamic and heat transfer optimization of an integrally cooled Aluminum and Silicon Carbide (Al/SiC) high current power hybrid package. Discussed herein are the design and supporting analyses for a module, suitable for electric power-train applications. These modules are constructed with insulated gate bipolar transistors (IGBT) and free wheeling diodes arranged in selected circuitry, supporting 3 phase motor control. Aluminum Silicon Carbide has evolved as a heat sink material of choice for certain high power hybrid packages. The ability to net shape cast Al/SiC allows for increased integration of the power stage heat exchanger with the package itself. Improved thermal management, increased power density, reduced weight and lower cost were all motivating factors for this work. The study, conducted at Motorola's Power Products Division indicates that heatsink designs and internal flow geometry's play a critical role in equalizing device junction temperatures. The study has shown that heatsink configurations exist that have minimal dependence on die placement, thus allowing for greater circuit flexibility. Results of three dimensional finite volume coupled-field computational fluid dynamic (CFD) and finite difference heat transfer analyses will be presented.