Effects of UV laser milling parameters on the profile cutting of Gorilla glass substrates

The purposes of this study were to develop a high-speed milling system combined with an ablation path of the parallel lines and to investigate the cut quality on the glass substrates conducted by a nanosecond pulsed Nd:YVO4 laser (λ:355 nm). Experimental specimens were commercial Corning Gorilla glass with a thickness of 800 μm. Laser milling parameters including the laser fluence, number of milling pass, and scan speed of galvanometers along the processing path were adjusted for the profile cutting of the glass substrates. The laser milled depth, surface morphology, and surface roughness of the glass substrates after laser milling were measured by a 3D confocal laser scanning microscope. Experimental results showed that the milled depth outstandingly increased as increasing the laser fluence and the number of milling pass or decreasing the scan speed of galvanometers. The milled depths averagely increased from 38 μm to 107 μm when the scan speed of galvanometers decreased from 1500 mm/s to 300 mm/s with the laser fluence of 52 J/cm2 in a one-cycle milling process. Moreover, the milled depths averagely increased from 107 μm to 185 μm when the laser fluence decreased from 54 J/cm2 to 95 J/cm2 with the scan speed of galvanometers of 300 mm/s. When the number of milling pass increased to 5 with the laser fluences of 95 J/cm2 and scan speed of 300 mm/s, the Gorilla glass substrate was cut through a square hole. The edge of milled hollow square structures on the glass substrate had few of micro cracks, square angles, and steep and oblique walls around the milled boundaries as increasing the number of milling pass. In addition, the value of surface roughness increased with increasing the numbers of milling pass.