The Capillary-driven Two-phase Embedded Microchannel Heatsink for the Efficient Cooling of Power Electronic Modules

The power electronic module is an integrated package of chips, including power MOSFET and diodes, for the application of power modulation. The evolution of power electronics leads to a more compact form factor and higher power density. The miniature size and the increased power density pose challenges to thermal management. The embedded microchannel coolers in the Direct Bonded Copper (DBC) substrate significantly improve the cooling performance (1, 2), but the high pressure drop is a critical drawback for coolers of this kind. The 3D manifold structure optimized the flow distribution and demonstrated a decrease in the pressure drop by 5-fold (from >200 kPa to <40 kPa) (3). However, there is room for further pushing the Pareto front.

In this study, a microchannel cooler with a wicking structure is proposed to leverage the potential of capillary flow and two-phase cooling to improve the cooling performance. The wicking structure at the surface of the channels transports the coolant via capillary force (4). Also, phase-change cooling removes heat by latent heat without a temperature increase (5). The design enables a much lower thermal resistance of the heat exchanger (< 0.2 cm2-W/K) that can operate at a much lower pressure drop (<5 kPa) for the application to the next-generation power electronic module.