Phase change material integrated cooling for transient thermal management of electronic devices

Phase change materials (PCM) used to buffer temperature swings in electronic devices have the potential to improve reliability and shrink the volume and weight of the thermal management system. Although PCMs have high latent heat of phase transitions between solid and liquid, they are only effective near their melting temperature. The limited temperature range of operation constrains their effective cooling performance to narrow operating conditions and presents a challenge for designing PCM integrated thermal management solutions that can operate over a broader range of power inputs and cooling conditions. This paper studies the effect of diverse operating conditions on the cooling performance on PCM-integrated power devices. We use a Field's metal-impregnated copper foam composite as our thermal buffer with an effective cooling capacity of 109.8 kJ/(m²·K^0.5·s^0.5), and integrate it with a circuit board-mounted top-cooled gallium nitride (GaN) device that undergoes transient operation. We measure the junction temperature of the device in response to different heating conditions, including single pulse and pulse train profiles, showing that the PCM can reduce the junction temperature swing as much as 21.3% when compared to a copper reference heat spreader, with a maximum temperature reduction of 9.2%. To analyze the physics of heat transfer within the device under varying operating conditions, we developed a three-dimensional finite element method (FEM) simulation of the PCM-integrated device and validated it with our measurements. We observe key attributes of the heat flow within the PCM-integrated device depending on different heating conditions and the phase change dynamics. Finally, we develop a reduced-order model (ROM), validated by both measurements and FEM simulations, which enables fast calculations of temperature response and enables PCM optimization.