Nanoporous evaporative device for advanced electronics thermal management

We report the design, fabrication and modeling of a thin film evaporation device for cooling of high performance electronic systems. The design uses a membrane with pore diameters of ~100 nm to pump liquid via capillarity to dissipate the high heat fluxes. Viscous losses are minimized by using a thin membrane (~200 nm) which is supported by a ridge structure that provides liquid supply channels. As a result, the external pumping requirements are low, enabling an integrated cooling device with a large coefficient of performance. By integrating the cooling solution directly into the substrate, the thermal resistance of the spreader and interface material are removed entirely. Pentane is used as the working fluid based on its dielectric properties, surface tension and latent heat of vaporization. We first developed a model to capture the heat and fluidic transport within the membrane and supporting ridge structure using conservation of mass, momentum and energy. Using the model, we conduct a parametric sweep of the ridge and membrane geometries to elucidate their influence on thermal performance. We then show how the temperature of hot spots can be managed with a customized cooling solution while independently managing the temperature of background heated regions through variation in the membrane porosity over a realizable range of 10 - 50%. This work provides design guidelines for the development of a high performance evaporator device capable of dissipating the extreme heat fluxes (> 1 kW/cm²) required for next generation high power electronic devices.