UVレーザによる高アスペクト比小径穴あけ加工 (第1報) : —ホウ珪酸ガラスへのアスペクト比190の穴あけ—

概要

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High-aspect-ratio microdrilling of borosilicate glass has been demonstrated by the forth harmonic of nanosecond Nd : YVO4 laser. Borosilicate glass plate with a thickness of 2 mm was drilled through. Firstly, the profile of the drilled hole was measured. As a result, diameters were φ8.2 ± 3.1 μm andφ6.3 ± 1.0 μm at the depth from 480 μm to 2040 μm and from 1360 μm to 2040 μm, resulting in an aspect ratio of higher than 190 and 100, respectively. Drilling process was observed by ceasing laser illumination every 500 pulses. Depth of the drilled hole increased ∼200 μm by very 500 pulses. Re-deposition layer with a thickness of a few micrometer was observed in the range from the top surface to a depth of 1600 μm. Inner surface of the drilled hole was observed by scanning electron microscope (SEM). Melted surface was observed at around the surface (in the range ∼100 μm from the surface) area. Debris with diameters of less than 500 nm was observed in the range of 100 μm - 600 μm from the surface. At around 650 μm, debris with diameters of 500 nm - 1 μm were recognized. In the area deeper than 700 μm, no clear debris was observed and flat surface was obtained. Cracks were observed in the same area where the re-deposition occurred.