Design for Additive Manufacturing and Thermal Management in GaN-Based Power Electronics Systems

GaN HEMTs on circuit boards used for power electronics applications suffer from the generation of excessive heat that may eventually destroy them. Both immersion and conduction (using a cold plate) methods for cooling have been evaluated in the past. The objective of this work is to design and build a cold plate solution to this thermal problem by means of forced convection through optimised cooling channels integrated into a cold plate. Considering the complex and convoluted shapes these fluid-flow channels take within enclosures that rest on the heat dissipating surface of the GaN chip, additive manufacturing based on powder bed fusion processing of a thermally conductive metal is a part of the solution. Finite volume (FV) simulations based on ANSYS Fluent module are used for evaluating thermal fields within the heat exchanger block resting on the GaN HEMTs, taken as the plate heat source. Initial impressions from the FV results indicate the design alterations evaluated to be suitable for better thermal management of GaN HEMTs. Physical prototyping of the cooling block was also successful based on additive consolidation of metallic powders by selective laser melting.