Effects of macro- and micro-hole milling parameters on Al₂O ₃ ceramics using an ultraviolet laser system

Ceramics are commonly used as substrates in electrically insulated integrated circuit, printed circuit board, and lightemitting diode industries because of their excellent dielectric and thermal properties. However, brittle materials (e.q., ceramic alumina, sapphire, glass, and silicon wafer) are difficult to fabricate using wheel tools. Laser material processes are preferred over traditional methods because they allow noncontact processing, avoid tool wear problems, and achieve high speed, high accuracy, and high resolution. Laser material processes also exhibit minimal residual thermal effects and residual stress. This study investigated the laser drilling of Al₂O ₃ ceramic material (with a thickness of 380 μm and hole diameters of 200, 300, and 500 μm, respectively) by using a laser milling method. The macro- and micro-hole milling performance depended on various parameters including the galvanometric scan speed and milling time. A 3D confocal laser scanning microscope and a field-emission scanning electron microscope were used to measure the surface morphology, taper angle, and melted residual height of the machined surface after laser milling. The edge quality and roundness of laser milling were also observed using image-processing edge-detection technology.