Analytical and experimental on the capillary rise of aluminum multi-scale microgroove wick structures

Ultrathin vapor chambers (VCs) are the most typically used heat-sink components in the development of thin and light electronic products. In this study, microgrooved aluminum wicks with multi-scale structures fabricated by two-step laser processing are developed to enhancing the performance of ultrathin VCs. The multi-scale microgroove wick is composed of the main groove and the multi-scale microstructures that include cluster particles, the gradient structure, and holes formed between cluster particles. The effects of the second step laser processing scan interval and the scan number on the surface morphology, wettability, capillary rise rate, and capillary performance parameters of the multi-scale microgroove structured wicks are investigated. The second-step laser processing changes the morphology of the main groove surface, which affects the wettability of the multi-scale microgroove structure. When the scan interval of second step laser processing is 0.05 mm and the scan number is 1, the droplets on the surface of the multi-scale microgrooves are completely immersed within 23.5 ms, which is 80.6% less than all the time of A1. In addition, the capillary rise velocity of the two-step laser processing multi-scale microgroove structure in the initial 3 s is 150% higher than that of the one-step laser processed microgroove wick, and the capillary performance parameters K/Reff improves by 114.15%.