Junction Temperature Control and Thermal Stability Enhancement Method for Power Devices Based on Vapor Phase-Change Principle

The total equivalent thermal capacitance of the junction-to-heatsink path in power devices significantly influences the junction temperature swing (ΔTj). As the equivalent thermal capacitance increases, ΔTj exhibits a decreasing trend. Based on this observation, this study proposes a junction temperature regulation method for power devices by modulating the thermal capacitance parameter using a liquid-to-gas phase change mechanism. A theoretical model of phase-change cooling is established to elucidate its regulatory mechanism on junction temperature, and experiments are conducted to quantify the operational boundaries of phase-change cooling. Experimental results demonstrate that this method optimizes the heat transfer process, improves the thermal network parameters of the device, and effectively controls both junction temperature fluctuations and average junction temperature, thereby enhancing the calculated thermal cycling lifetime of the device.