Multiscale Freestanding Vertically Aligned CNT Heat Sink Enabling Multimodal Heat Dissipation by Conduction, Convection, and Radiation

A vertically aligned carbon nanotube (VACNT)-based heat sink is demonstrated for passive multimodal thermal management applicable for electronic and semiconductor devices. The VACNT enables multimodal heat dissipation through axial conduction, convection facilitated by its nanoporous morphology, and radiation enabled by its superior emissivity. While conventional metallic heat sinks suffer from low surface emissivity and require complex post-processing to enhance radiative cooling, the proposed VACNT overcomes these limitations by providing an inherent multiscale structural hierarchy without secondary surface treatments. The thermal conductivity of the freestanding VACNT (500 to 1500 µm heights) is characterized using laser flash analysis and differential scanning calorimetry as 32 to 40 W/mK. Evaluated on a Raspberry Pi Zero 2 W platform, the 1500 µm-high VACNT heat sink decreases the peak CPU temperature by 10.7°C compared with a bare CPU. The VACNT can be patterned into the topographic architecture to further improve heat dissipation by increasing the surface area, achieving a 6.7°C lower peak CPU temperature than a conventional aluminum heat sink. Cyclic stability test confirms consistent thermal performance over repeated use. The VACNT practically allows various configurational engineering by molding, rolling, scissoring, and tiling, showcasing its versatility for diverse thermal management applications.