An All-Metal Hollow Microstructure for Pool-Boiling Chip-Integrated Cooling Based on Electroplating

This paper reports an all-metal hollow microstructure designed to enhance pool boiling heat transfer. The structure is composed of a double-cross-layered strip metal array, with micron-sized array cavities. The all-metal structure supplies a highly efficient heat transfer path between the heat source and the working fluid. The cavities provide more nucleation sites than bare surface. The strip metal array prevents bubbles from combining with each other and provides a capillary-driven liquid-imported mechanism which fully supplies water to the bottom of bubbles to accelerate their escape. The micro-electroplating and sacrificial layer technology were used to fabricate the structure on the simulated chip heating surface. A low-temperature and low-cost manufacture route compatible with chip fabrication was established. A real time testing system with a thermal infrared imager and a high-speed camera was built to assess the heat transfer performance of the boiling surfaces during nucleate boiling. At a superheat of 20 °C, the heat flux dissipated by this double-layered hollow structure in DI water at saturation temperature was 400% of that on the bare silicon surface, and the heat transfer coefficient reached 50,000 W/(m²K). This design provides new possibilities for low-cost process and 3D boiling-enhanced structures design to improve cooling efficiency and prevent dry-out.