Investigation of thermal management performance of electronic devices with phase change materials and pin fin heat sinks under periodic heating and cooling cycles

Effective thermal management is critical for high-power devices such as metal–oxide–semiconductor field-effect transistors, as excessive heat can degrade their performance and reliability. Existing studies often simplify the heat source as a region of constant power, overlooking the effects of periodic thermal cycling. Moreover, there is a lack of investigation into heat accumulation under cyclic power loads, and comparisons of pin fin geometries frequently neglect volume consistency. This study addresses these gaps by developing a three-dimensional transient model of a SiC-based metal–oxide–semiconductor field-effect transistor system which can operate stably within 150 °C, incorporating a sinusoidal power load and material-specific heat generation zones. The thermal performance under varying phase change material types, pin fin shapes, and volume ratios was numerically evaluated. Results show that microencapsulated phase change materials reduced the average temperature by 15.7 %, and adding expanded graphite improved temperature uniformity, lowering the peak temperature difference by up to 36.9 °C, because the expanded graphite enhances the responsiveness of the phase change material to heating and cooling processes. Circular fins achieved the lowest average temperature at 121.9 °C, while a 12 % fin volume fraction further reduced temperature by 12.4 % and enhanced uniformity by 176.1 %. These results highlight an effective strategy for improving cooling in cyclic thermal environments.