Lung-inspired PCM-impregnated heat sinks for transient thermal management of high-power GaN electronic chips

Conventional passive heat sinks cannot effectively cool new-generation high-power Gallium Nitride (GaN) transistors during their peak transient operation modes. Heat sinks impregnated with phase change materials (PCMs) have recently gained considerable attention due to their potential to mitigate temperature overshoot of high-power electronics during their peak transient operation. However, state-of-the-art PCM heat sink designs, in which a PCM rests between the hot electronic chip and cooling fluid, suffer from a low cooling performance when the PCM is in a single-phase state (either frozen solid or melted liquid). This is mainly attributed to the low thermal conductivity of PCMs, which acts as a thermal barrier between the hot chip and the cooling fluid. This study introduces a novel lung-inspired PCM-impregnated heat sink for transient thermal management of highpower electronics. Here, the cooling fluid volumetrically penetrates through and within the PCM to the vicinity of the hot electronic chip. As such, the lung-inspired heat sink design reduces the thermal resistance between the hot chip and the cooling fluid. First, the transient cooling performances of three lung-inspired PCM-impregnated heat sink designs with different PCM volume contents are numerically evaluated. Then, the most promising design is 3D-printed with aluminum to explore its transient cooling performance experimentally using a GaN transistor and Field's metal PCM. The experimental results show the embedded PCM can maintain the junction temperature of the GaN transistor at about 60 similar to 65 degrees C (i.e., the melting point of Field's metal) for 270 seconds when a peak power intensity of 62 W/cm(2) is applied. The intuition achieved from this study provides a new PCM-impregnated heat sink design suitable for transient thermal management of high-power electronics.