Investigation of Z-type manifold microchannel cooling for ultra-high heat flux dissipation in power electronic devices

Ultra-high heat flux (up to 1000 W/cm2) thermal management has been an urgent need for advanced power electronic devices to maintain their superior electrical performance and reliability. Embedded microchannel cooling is a promising and challenging thermal management method for high-heat-flux chips. This study presents an embedded Z-type manifold microchannel (Z-MMC) cooling design for a 5 x 5 mm2 heating zone, which can dissipate an ultra-high heat flux up to 1842 W/cm2 by using water single-phase flow. The microchannel array is etched on silicon wafer, while the manifold structure is fabricated by PDMS molding. The test chips are assembled using O2 plasma bonding technique, which provides an observation window for visualizing the flowing state of the coolant during the heat transfer process. We experimentally test and compare four test chips with different microchannel geometries and manifold designs. The average heater temperature, temperature distribution, thermal resistance, heat transfer coefficient and pressure drop are reported for mass flow rates of 2-6 g/s. The proposed Z-MMC cooler is capable of dissipating up to 1800 W/cm2 with a total thermal resistance of only 0.075 cm2 center dot K/W (only 0.039 cm2 center dot K/W after subtracting the conduction thermal resistance), at a flow rate of 6 g/s and a pressure drop of 54 kPa. Compared to the rectangular manifold arrangement, the trapezoidal manifold demonstrates a lower temperature rise, a more uniform temperature distribution and a smaller pressure drop at the same heat flux and flow rate, mainly due to a more uniform fluid distribution in the microchannel. Furthermore, we compare our proposed design's thermo-hydraulic performance with those of representative manifold microchannel cooling data in the literature, and the proposed Z-MMC design demonstrates relatively low thermal resistance and pressure drop values.