Superhydrophobic/Superhydrophilic Hybrid Copper Surface Enhanced Micro Heat Pipe by Using Laser Selective Texturing

Abstract

The heat transfer performance of Flat micro heat pipe (FMHP) is mainly determined by liquid absorption capacity of the wick. A chemical-free laser selective micro-texture technology is proposed for the fabrication of FMHP. Series of samples with different widths of the superhydrophobic-superhydrophilic spacing stripes were prepared by laser micro texturing, and their transport capacity was tested. Scanning electron microscope, three-dimensional optical profiling, and X-ray photoelectron spectroscope techniques were used to characterize the surfaces, and the mechanism of accelerating liquid reflux was investigated. Two samples with the same spacing width were used to make FMHPs. The heat transfer performance of each group of FMHPs was tested, including the start-up time, steady state temperature, and axial maximum temperature difference, and the corresponding thermal resistances were calculated. The results show that the width of superhydrophobic-superhydrophilic spacing stripes can affect the capillary force and hysteresis force during droplet transport, thereby affecting the droplet transport velocity, and in turn, influencing the heat transfer performance of the FMHP. Compared with most current flat micro heat pipes, the laser selective textured heat pipe with superhydrophobic-superhydrophilic stripes can significantly improve the heat transfer performance, and is promising for heat transfer applications in microelectronic equipment.