Topology Optimized Fin Designs for Base Plate Direct-Cooled Multi-Chip Power Modules

Advances in wide bandgap (WBG) semiconductor technologies have enabled the development of highly-compact multi-chip power modules for various applications. Direct cooling approaches, where the coolant circulates and directly contacts the module base plate, have demonstrated the ability to reduce junction-to-coolant thermal resistance more than 10% by eliminating the thermal interface materials. This study focuses on the design methodology of the module base plate fins to enable high performance direct cooling for the power modules. A two- dimensional two-layer topology optimization algorithm is developed and used to optimize the thermal-hydraulic performance of the fins, with thermal performance mapped in terms of the device average temperatures along with the chip-to- chip temperature difference with pressure drop characterizing the hydraulic performance. The silicon carbide (SiC) power platform XM3 from Wolfspeed is used as a reference for designing the finned base plate. Detailed three-dimensional conjugate heat transfer and fluid flow numerical simulations are used to characterize the finned base plate designs. The simulations use operating conditions relevant for EVon-board power converter systems. These include inlet coolant flow rates ranging from 1 LPM per module at inlet temperature of 30°C, and heat dissipation of 50 W per SiC device. Performance of the topologically optimized designs is compared with conventional fin designs.