APPLICATION OF TAGUCHI METHOD IN THE OPTIMIZATION OF LASER MICRO-ENGRAVING OF PHOTOMASKS

Abstract

Abstract: Photomasks are needed to generate various design patterns in the fabrication of liquid crystal displays (LCDs). This paper discusses the use of the Taguchi method of experimental design in optimising process parameters for micro-engraving of iron oxide coated glass using a Q-switched Nd:YAG laser. The effects of five key process parameters- beam expansion ratio, focal length, average laser power, pulse repetition rate and engraving speed- have been explored. The primary response under study is the engraving linewidth. An L16 orthogonal array was used to accommodate the experiments. The study indicated that a minimum linewidth of 18 mm could be obtained with beam expansion ratio of 5 ´, focal length of 50mm, laser average power of 0.4 W, pulse repetition rate of 5 kHz, and engraving speed of 5000 mm/min.