Fabrication of copper-based two-tiered surface microstructures by picosecond laser micromachining in combination with electrodeposition for enhanced two-phase heat transfer

Multiscale copper-based surface microstructures are required in miniaturized two-phase heat exchange devices. In this study, we propose a method that combines picosecond laser micromachining and electrodeposition to prepare copper-based two-tiered surface microstructures. The surface structures consist of periodic mini-grooves covered by dense microcones. The mini-grooves, prepared using ultrafast laser micromachining, offer a superior capillary transport performance. On the other hand, the microcone structures, prepared by electrodeposition, provide more effective nucleation sites for liquid–vapor phase changes. Compared to single-tiered mini-groove structures, the minigroove-microcone composite structures demonstrate an 8.2% increase in critical heat flux (CHF) and a 21–58% increase in heat transfer coefficient (HTC) during capillary-fed boiling tests. The method presented in this study introduces a new approach for fabricating high-performance wick structures suitable for ultrathin two-phase heat exchange devices.