Manufacturing and capillary properties of printed multi-scale wicks for ultra-thin heat pipes

Ultra-thin heat pipe (UTHP) holds great potential in cooling miniaturized and highly integrated electronic devices that face severe heat dissipation challenges. The capillary wick is a critical component that influences the thermal performance of UTHPs. However, minimizing the thickness of the wicks while maintaining the high capillary performance could be mutually exclusive. Here, an ultra-thin printed multi-scale powder wick (UPMPW) with controllable permeability was developed using copper powder printing technology and pore-forming technology. The permeability of the wicks can be improved by the multi-scale structure, enhancing the overall capillary performance. Results show that the maximum permeability of UPMPW is 9.16 × 10 −11 m 2 , which is 11.6 times higher compared with the wick prepared without the addition of Potassium carbonate as the pore-forming agents, implying that the permeability can be significantly improved. The UPMPW, sintered with the addition of 30 wt% pore-forming agents, yields the best wicking coefficient of 8.54 mm/s 0.5 , improving by 17.3 % compared with the printed uniform powder wick. Meanwhile, the volumetric flow rate is significantly improved by 99.4 %. With thickness of only 0.3 mm and good capillary performance, UPMPW offers a highly efficient pathway towards achieving effective thermal performance of UTHP and cooling compact electronic applications. • Ultrathin multi-scale powder wick with controllable permeability was developed. • The developed wick achieves significant enhancement in capillary performance. • Mass ratio of pore-forming agents can be regulated to obtain optimum performance. • Wicking coefficient of ultrathin multi-scale powder wick could reach 8.49 mm/s 0.5 .