Comparison of diamond drilling and laser drilling techniques in glass drilling for fabrication of MEMS

摘要

This paper aims to investigate a cost effective drilling process to achieve near chipping free edge quality in glass drilling for fabrication of a new MEMS device. Both diamond drilling and laser-machining are studied in this research. The diamond drilling test is performed on a CNC machine tool using multilayered diamond drill, together with water as coolant. The laser machining test is carried out on a Nd:YAG laser machine in which the laser beam is focused onto the sample surface through a beam expander. Taguchi method has been applied to select the optimized machining parameters, such as cutting speed, feed rate, power, wavelength and repetition rate in the diamond drilling and laser machining processes, respectively. The edge qualities of the drilled holes are inspected by an optical microscope. The optimized machining conditions for diamond drilling are 2,500 rpm spindle speed and 0.25 mm/min feedrate with mist water as coolant. 32kW power and 17,500 Hz frequency are the optimized parameters for laser drilling. The transparent glass is difficult be machined by laser but the good edge quality can be obtained by CNC diamond drilling.