Single phase liquid cooling of hotspots in a heterogeneous pin-fin-enhanced microgap with non-uniform fin array

Single-phase liquid cooling in microchannels and microgaps has been successfully demonstrated for heat fluxes of ~1 kW/cm² in Si components. Surface area enhancements such as uniformly distributed pin-fin arrays can provide further improvements in cooling performance. However, effectively managing localized hot spots in heterogeneous integration (HI), which refers to the integration of various components that achieves complex functionalities, entails a thermal challenge. Here we address this thermal challenge of HI by using nonuniform pin-fin array-enhanced microgap liquid-cooling. This paper tests the liquid-cooling performance of four test device vehicles (TDVs), each with a pin-fin-enhanced microgap with non-uniform fin arrays. Multiple combinations of hot spot and background heat fluxes are evaluated. Nonuniform heating conditions were created using four background heaters located from the upstream to the downstream, and one additional hotspot heater located in the center. Thermal performance of cylindrical fin-enhanced TDVs and hydrofoil fin-enhanced TDVs are examined. Both have two designs: one with increased fin density around the hotspot only, and another with increased fin density along the spanwise direction. Deionized (DI) water is the coolant for all test cases, with heat flux varying from 125 W/cm² to 625 W/cm² for the hotspot, and 125 W/cm² to 250 W/cm² for background heaters. The resulting heat flux ratio of the localized hotspot to background heaters varies from 1 to 5. The TDVs of the spanwise-increased hydrofoil fins exhibited the best thermal performance-6% to 14% lower hotspot temperature than others. The TDVs of the spanwise-increased cylindrical fins maintain a balance between hotspot cooling performance and pressure drop. In general, as the temperature of hotspot remains around 70°C with a heat flux of 625 W/cm², the non-uniform fin-enhanced microchannel-cooling technology appears to be a promising hotspot thermal management approach under moderate background heat flux.