Abstract
The fundamentals of laser beam drilling were studied using a high peak pulse CO2 laser. Specifically, those areas examined were the effects of the beam-plasma interaction and heat accumulation near the irradiation point during multipulse irradiation on the characteristics of drilling Si3N4 ceramics and acrylic resin (PMMA). In the case of beam-plasma interactions, the drilling efficiency and hole shape were compared in a vacuum and in air. For heat accumulation, holes formed with a few pulse frequencies, which had enough time to cool, were compared with those formed at higher pulse frequencies. The results revealed that in the case of drilling Si3N4 in air, beam scattering by the plasma plume decreased drilling efficiency and increased the hole diameter. Also, decreasing the pulse duration or drilling in a vacuum can successfully improve the drilling efficiency. Furthermore, in PMMA, the hole diameter of low aspect ratio holes were greatly increased by heat accumulation, and as the aspect ratio increased there was a significant increase in hole diameter caused by the beam scattering by the plasma plume.
