Layer-by-Layer Assembled Phase Change Composite for Heat Spreader with Enhanced Cooling Capacity

Abstract

This study reports fabrication of layer-by-layer assembled phase change composites by locating phase change material (paraffin) into the network of aluminum meshes after which they are sandwiched by ultra-thin graphite sheets. The fabricated phase change composites with 90 vol% phase change materials exhibit up to 285 times higher thermal conductivities than bare paraffin with directional characteristics of heat flow due to the incorporation of graphite sheets which have anisotropic thermal conductivities. We further examine thermal performance of bare paraffin, aluminum, and phase change composite heat spreaders by monitoring maximum hot-spot temperatures under different cooling conditions. As a result, the phase change composite heat spreaders perform superior cooling capacities to bare paraffin and aluminum heat spreaders in high power intensity conditions with high heating and low cooling rates by lowering their hot-spot temperatures by up to 121 degrees C and 7 degrees C, respectively. It is enabled by the effective utilization of thermal capacitive effects of phase change materials with significantly enhanced thermal conductivities. This study represents an effort to develop novel heat spreaders with enhanced cooling capacities for the potential applications of high thermal budgets with limited cooling resources.