Add-On Microchannels for Hotspot Thermal Management of Microelectronic Chips in Compact Applications

This paper demonstrates an experimental micro- channel solution to cool microelectronic chips with hotspots, using an integrated, yet nonintrusive technique. In microelectronics, approaches such as die thinning induce acute stress on cooling because it increases the hotspot phenomena and reduces chip bulk thickness that could be used for microchannels. In compact devices, heat must be removed using limited pumping power and cooling space. Microchannels etched in the backside of the chip, usually considered as an efficient cooling solution, are impracticable on highly thinned chips. This paper experimentally investigates the cooling performance of a noninvasive and hotspot aware microchannel die that is in direct fluidic contact with the backside of the microelectronic chip. It also proposes a confinement-wise metric. A thermal resistance of 2.8 °C/W is achieved at a heat flux of 812 W/cm 2 per heat source, for a total dissipated power of 20 W and a maximum allowed temperature rise of 55 °C. Such performance is obtained with only 19.2 kPa of pressure drop and 9.4 ml/min of flow rate, corresponding to a hydraulic power of only 3 mW and a coefficient of performance of 6500. In addition, the complete chip stack, including the thinned chip, measures only 660~\mu \text{m} high. Therefore, backside cooling appears to be a promising compact and low consumption solution for compact electronic applications having confined hotspots.