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

Y. H. Chen¹, S. C. Tam², W. L. Chen¹ and H. Y. Zheng¹  
(1) Gintic Institute of Manufacturing Technology      
Nanyang Technological University
71 Nanyang Drive Singapore 638075
(2) School of Electrical & Electronic Engineering
Nanyang Technological University      
Nanyang Avenue, Singapore 639798

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 line width.  An L16 orthogonal array was used to accommodate the experiments.  The study indicated that a minimum line width of 18 mm could be obtained with beam expansion ratio of 5 times,  focal length of 50 mm,  laser average power of 0.4 W,  pulse  repetition rate of 5 kHz, and engraving speed of 5000 mm/min.

Keywords:  Laser engraving, photomasks, Taguchi method, parameter optimisation

Full paper in PDF

Reprinted from International J. of Materials and Product Technology, Vol. 11, No. 3/4 (1996), 333-344
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