PCM-impregnated heat sinks for transient thermal management of GaN electronic chips

Heat sinks impregnated with phase change material (PCM) are considered promising solutions for transient thermal management of future high-heat-flux GaN transistors. Existing PCM-impregnated heat sink designs, however, suffer a low cooling performance in their steady-state operation as the PCM layer sits between the cooling fins and the chip. This study introduces a novel lung-inspired PCM-impregnated heat sink design to volumetrically distribute the cooling air through and within the PCM and the solid fins. As such, the proposed PCM heat sink reduces the thermal resistance between the electronic chip and the cooling fluid during both steady and transient operational modes. The cooling performances of three lung-inspired PCM-impregnated heat sink designs at various PCM volumetric ratios are first numerically evaluated under a transient heat input scenario. Then, the transient cooling performance of the optimized PCM-impregnated heat sink design is further investigated using three representative heat sink body materials of a high thermal conductivity polymer, alumina, and aluminum. The results indicate a PCM-impregnated heat sink made of a high thermal conductivity material is still needed for transient thermal management in many industrial electronic chips. Also, it was found that a PCM-impregnated heat sink made of ceramic might be suitable for military-grade electronic chips. The insights gained from this study could help the design of advanced PCM-impregnated heat sinks for optimum thermal management of future high-heat-flux electronic chips.