Microchannel Cooling Strategies for High Heat Flux (1 kW/cm(2)) Power Electronic Applications

Abstract

The wide band-gap (WBG) semiconductor electronics such as silicon carbide (SiC) and gallium nitride (GaN) are becoming more popular in power electronics applications due to their excellent functionality at higher operating temperatures, powers, frequencies and in high radiation environments compared to Si devices. However, the continued drive for higher device and packaging densities has led to extreme heat fluxes on the order of 1 kW/cm(2) that requires aggressive microchannel cooling strategies in order to maintain the device junction temperature below acceptable limits. A reduced order single/two phase thermal-fluidic model is developed to investigate the effect of micro-channel geometry parameters, packaging materials and fluid flow conditions on the cooling performance of various cooling strategies. Water and R245fa refrigerant are used as single- and two-phase working fluids, respectively. We consider three cooling strategies: Design A: copper cold-plate micro-channel module bonded to the device substrate Design B: embedded micro-channels directly etched into the device substrate and Design C: embedded micro-channels with a 3D manifold with inlet and outlet module. The proposed embedded micro-channels with 3D manifold with R245fa working fluid has the potential to achieve the lowest thermal resistance similar to 0.07 K/W and pressure drop similar to 10 kPa for flow rate Q similar to 0.21 1/min (T-in = 90 degrees C) and exit quality x = 0.44.