Fabrication of micro pin fins on inclined V-shaped microchannel walls via laser micromilling

A laser-micromilling process was developed for fabricating micro pin fins on inclined V-shaped microchannel walls for enhanced microchannel heat sinks. A pulsed nanosecond fiber laser was utilized. The feasibility and mechanism of the formation of micro pin fins on inclined microchannel walls were investigated for a wide range of processing parameters. The effects of the laser output power, scanning speed, and line spacing on the surface morphologies and geometric sizes of the micro-pin fins were comprehensively examined, together with the material removal mechanisms. Micro pin fins with acute cone tips were readily formed on the V-shaped microchannel walls via the piling of recast layers and the downflow of re-solidified materials in the laser-ablation process. The pin-fin height exhibited an increasing trend when the scanning speed increased from 100 mm/s to 300 mm/s, and it decreased continuously when the line spacing increased from 5 mu m to 20 mu m. The optimal processing parameters for preparing micro pin fins on V-shaped microchannels were found to be a laser output power of 21 W, scanning speed of 100-300 mm/s, and line spacing of 2-5 mu m. Moreover, the V-shaped microchannels with micro pin fins induced a 7%-538% boiling heat-transfer enhancement over their counterpart without micro pin fins.

Automated summary

A laser-micromilling process was developed to fabricate micro pin fins on inclined V-shaped microchannel walls for enhanced heat sinks. The height of the pin fins increased with scanning speed but decreased with line spacing. Optimal processing parameters were found to be a laser output power of 21 W, scanning speed of 100-300 mm/s, and line spacing of 2-5 μm.