Stacked microchannels provide larger flow passages, so that for a fixed heat load the required pressure drop is significantly reduced. One unique feature of the stacked microchannel heat sink is that individual layers populated with parallel microchannels or distributing manifolds can be bonded into one stack with independent flow path. As a beneficial result, flexible control over the flow direction and flow rate can be harnessed to achieve better temperature uniformity and the low junction temperature. In the present work, stacked microchannels with different flow arrangement have been fabricated on silicon wafers using micromachining techniques. Platinum thin film heaters are deposited on the backside of the stacked structure to provide heating. In a close-loop setup, water is pumped through the microchannels to carry the heat from the heaters to a remote liquid-liquid heat exchanger rejecting the heat to a recirculating chiller. Wall temperature along the flow direction is measured at nine locations using platinum resistive temperature detectors deposited at the same time as the heaters. Good overall cooling performance (0.09°C/(W/cm2)) for the stacked microchannel heat sink has been shown in the experiments. It has also been identified that over the tested flow rate range counter-flow arrangement provides better temperature uniformity, while parallel flow has the best performance in reducing the peak temperature.

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