Analysis of process parameters of laser structuring with Taguchi method

This paper discusses the use of the Taguchi method of experimental design for optimizing process parameters for laser structuring, using a Q-switched Nd:YAG laser. The effects of six key process parameters—laser power, number of pulses, pulse repetition rate, bite size (each laser pulse irradiation on PI substrate overlapped with the next one), focal length, and thickness of tin layer—are explored. The primary topic under study is the space profiles between circuit lines in a printed circuit board (PCB) after laser structuring: space width d, space depth z, and resolidification height h. The important factors that influence the profile of circuit space in laser structuring, and the best set of process parameters are found. According to an analysis of variance (ANOVA), it can be concluded that laser power and the number of pulses are the most important parameters in the laser structuring process that influence all the three parameters of space width, space depth, and resolidification height. Some other parameters were also considered in the experiment such as repetition rate and bite size. The thickness of the tin layer and the laser focal length have only a minor influence on the experimental results.