A picosecond laser in spin-cutting mode was used to drill 500μm diameter microholes on 150μm thick aluminium nitride ceramic. The effects of laser processing parameters such as the laser power, scanning speed, and defocus amount on the microhole quality were studied. The results show that as the laser power increases, the inlet and outlet diameters of the holes increase, the taper decreases slightly, and the thickness of the recast layer decreases evidently. The scanning speed has no obvious effect on the diameter and taper of the hole; however, the hole can not be drilled through when the speed is too large. Positive defocus can effectively reduce the taper of the hole. Under 28.5W laser power, 400Hz frequency, 200mm/s scanning speed, and zero defocus amount conditions, high-quality microholes with a taper of 0.85° were obtained.
The Gaussian laser beam was used to drill micro-holes with a diameter of 500μm on a 0.15mm thick aluminum nitride (AlN) ceramic. The geometry, processing quality, and surface fusion of the micro-holes were studied. The fusion recast layer at the edge of the hole is thick, the inner wall of the hole has a lot of slag, and the side wall of the laser entrance area is seriously inclined. Through spatial reshaping and focusing of Gaussian light, Bessel light with higher energy density, greater depth of focus, and smaller beam spot was achieved and used to perforate AlN ceramics. The fusion recast layer at the periphery and inner wall of the hole are both very thin, and the taper of the hole is very small. These results show that the focusing adjustment of the laser beam has a significant impact on the processing quality of AlN ceramic micro-holes.
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