Single Phase Liquid Cooling of High Heat Flux Devices With Local Hotspot in a Microgap With Nonuniform Fin Array

Abstract

Single-phase liquid cooling in microchannels and microgaps has been successfully demonstrated for heat fluxes of ∼1 kW/cm2 for silicon chips with maximum temperature below 100 °C. However, effectively managing localized hotspots in heterogeneous integration, which refers to the integration of various components that achieve multiple functionalities, entails further thermal challenges. To address these, we use a nonuniform pin-fin array. Single phase liquid-cooling performance of four silicon test chips, thermal design vehicles (TDVs), each with a nonuniform pin-fin array, are experimentally examined. We evaluate multiple combinations of hotspot and background heat fluxes using four background heaters aligned upstream to downstream, and one additional hotspot heater located in the center. We examine the thermal performance of cylindrical fin-enhanced TDVs and hydrofoil fin-enhanced TDVs, both with two designs: one with increased fin density around the hotspot only, and another with increased fin density spanning the entire width of the channel. The resulting heat flux ratio of the localized hotspot to background heaters varies from 1 to 5. TDVs with spanwise increased hydrofoil fin density (spanwise hydrofoil) exhibit the best thermal performance with 6% to 14% lower hotspot temperature than others. TDVs with spanwise increased cylindrical fin (cylindrical spanwise) maintain a balance between hotspot cooling performance and pressure drops. In general, as the temperature of the hotspot remains around 70 °C with a heat flux of 625 W/cm2, the nonuniform fin-enhanced microgaps appears to be a promising hotspot thermal management approach. The pressure drop of hydrofoil spanwise chip is highest among all the cases.