Temperature-leveling performance comparison of solid–solid phase change materials for thermal management of electronic chips in thin devices

Thermal management using solid–solid phase change materials (PCMs) is gaining attention as a viable technology for improving the reliability of smart devices, such as smartphones and tablets. This technology relies on the latent heat of PCMs to level temperature fluctuations in electronic chips, does not require additional power, and can be miniaturized. The temperature-leveling performance of thermal management devices based on solid–solid PCMs depends on the thermophysical properties and thickness of the PCM and the generated heat density of the heat source. However, these factors complicate the comparison of PCM performances. Therefore, clarifying the relationship between these factors and temperature-leveling performance of solid–solid PCMs and defining a performance factor are necessary for material development. In this study, we defined an evaluation index of PCMs suitable for thin smart devices. The temperature-leveling performances of VO2 and NiTi alloys, which are typical inorganic solid–solid PCMs, were compared to define the performance factor. Thermal simulations were performed to define and calculate the optimum PCM thickness that maximized the temperature-leveling performance and cost-effectiveness under various heat densities generated by a heat source. We defined the maximum effective energy capacity (Eeff) as the temperature-leveling performance factor, calculated using the optimal thickness and volumetric latent heat. PCMs with high Eeff are promising for thin smart devices. The simulation results indicated that Eeff of NiTi was 1.46–1.50 times higher than that of VO2 owing to the high thermal conductivity of NiTi. The simulation and experimental results were compared to validate the proposed thermal simulation model.