Phase change material integrated vapor chamber for transient thermal management

• Novel solid/liquid phase change integrated vapor chamber (PCM-VC)demonstrated. • Transient power pulses are efficiently managed with PCM-VC compared to no PCM situation. • Metallic materials are superior to organic phase change materials for thermal management of transient power pulses. • Upto 103% increase in the number of cycles to failure estimated. Temporal fluctuations in power consumption and associated temperature in electronic devices lead to performance degradation and early device failure due to thermal fatigue. These issues are prevalent in applications such as power inverters, data center servers, and others. Effective transient thermal management is critical to mitigate these issues and prolong device lifespan. This study presents the design, development, and experimental evaluation of a novel vapor chamber heat sink integrated with solid–liquid phase change materials (PCMs) to reduce temperature spikes under transient power pulses. The reported prototype features PCM integration inside a vapor chamber and a micro-pillar capillary wick fabricated by electroplating onto the inner surface of the condenser. Tests are conducted under different dual-power pulse conditions using two PCM types with an identical melting temperature of 58 °C: a low thermal conductivity paraffin-based PCM and a high thermal conductivity metallic alloy PCM, with more than 10 times higher figure-of-merit than the paraffin-based PCM. It is observed that the paraffin PCM-integrated vapor chamber has significantly larger evaporator temperature fluctuations than the metallic alloy PCM, indicating the importance of PCM selection for transient thermal management. Integrating PCM into the vapor chamber reduced temperature swings by 0.9 to 2.1 °C and the maximum evaporator temperature by 2 to 6.2 °C compared to the vapor chamber without PCM. The most pronounced reduction in temperature swing occurs when operating around the PCM melting point, underscoring the importance of the PCM melting point in thermal design. Standard deviation in transient temperature corresponding to transient power reveals a more than 23% improvement in temperature stability when metallic PCM is integrated inside the vapor chamber. Lifetime analysis prediction using the Coffin-Manson-Arrhenius model suggests a 76 to 134% increase in the number of cycles to failure, using the fatigue exponent value adopted from literature. Findings from this study showcase the promising capability of novel PCM-integrated two-phase cooling devices for effective transient thermal management and prolonged device life by suppressing thermal fatigue.