Effect of laser ablation surface modification on the capillary performance of the wick structure for ultra-thin vapor chamber

The rapid development of high-performance microelectronic devices requires high-performance ultra-thin vapor chamber (UTVC) based on phase change thermal conductivity to meet their heat dissipation requirements. Wick structure, the key component of UTVC, plays a decisive role in the heat transfer performance of UTVC. Due to the smooth surface and limited capillary force of the original wick structure, the improvement of the heat transfer performance of the UTVC was seriously restricted. In order to effectively improve the capillary performance of the wick and further improve the heat transfer performance of the UTVC, a laser ablation surface modification process was proposed in this paper. The influence of pulse energy and spacing between the adjacent pulses on the surface morphology and capillary performance of the wick structure was analyzed. The results show that laser ablation can produce rough micro-nano structures on the surface of the wick structure, which effectively improve the hydrophilicity and capillary performance of the wick structure. With the increase of pulse energy and spacing between the adjacent pulses, the capillary performance of the wick structure increases first and then decreases. The optimum process parameters of pulse energy and spacing between the adjacent pulses were 1.2 mJ and 15 mu m, respectively. Compared with the original wick, the capillary rise height of spiral woven mesh and copper mesh were increased by 23.63 % and 15.38 %, respectively. In addition, the maximum heat transfer power of the UTVC without and with laser ablation (optimal parameter) was 8 W and 10.5 W, respectively.