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|Thermal Stress Analysis in a Multilayer Power Module|
|Keywords: power electronics, silicon carbide, themal stress|
|The focus of this work is to analyze the thermo-mechanical stresses in multichip power module (MCPM) systems being developed for high-temperature power electronics applications. Silicon Carbide (SiC) based electronics show considerable promise for demanding applications (hybrid electric commercial and combat vehicles, interplanetary exploration, power distribution, etc.) due to its capability to withstand temperatures upwards of 600°C. While high-temperature SiC based systems are an enabling technology for a wide range of applications, the high-temperatures introduce exceedingly high stresses in the system due to the CTE mismatches between the different materials in the structure. High thermal stresses in the die or solder interface may result in peeling or fracturing, and thus are a major reliability concern for these systems. This paper investigates the case of a single SiC device bonded to a thick metal power substrate using a variety of solder alloys. Finite element analysis (FEA) software is employed to evaluate the shear stress, peeling stress, and normal stresses in the examined over temperatures ranging from 25 to 700°C. Multiple solder thicknesses and die geometry are analyzed in order to determine an optimal bond line. The FEA results are compared to several well adopted analytical approaches for comparison. In addition, methods to reduce the overall stresses are presented.|
|Rahul Rajgarhia, Graduate Student
University of Arkansas