Laser-processed wickless vapor chambers harness phase change to enable forced-air cooling of high-heat-flux electronics

Traditional electronics cooling approaches often employ fins placed directly on top of heat-generating elements (e.g. CPUs or GPUs). While such methodologies are often sufficient to handle general heat loads, they prove insufficient in scenarios that involve smaller hotspots generating considerably higher thermal heat fluxes, i.e., of the order of hundreds of W/cm 2 . We develop a thermal test-bench capable of generating extremely high heat fluxes from two switching MOSFETs – emulating real-life operational scenarios. Thereafter, we show that incorporation of optimized wick-free vapor chambers (VCs), comprising of wettability-patterned, laser-textured evaporators and condensers, can effectively act as enhanced phase-change heat spreaders, reducing overall heat fluxes at the heat ejection site, and therefore enabling the deployment of traditional cooling methodologies, like forced-air circulation. The optimized VCs had consistently low thermal resistances of 0.09 K/W even at die heat fluxes of 400 W/cm 2 . Interestingly, these devices show no variation of thermal resistance with change in heat input, with the lowest measured thermal resistance being 0.04 K/W at ∼50 W/cm 2 . Further, numerical simulations attest to the improved performance of these devices with incorporation of wettability patterns. An iterative numerical algorithm coupled with a CFD solver determines the orthotropic conductivities of the wettability-patterned heat spreaders enabling their rapid characterization and testing before experimental development. The present methodology highlights the role and importance of wick-free VCs, along with their advantages over traditional wick-lined VCs in air cooling of high-heat-flux electronic components.