Screen printing process design of experiments for fine line printing of thick film ceramic substrates

Screen printing has been the dominant method of thick film deposition because of its low cost. Many experiments in industry have been done and many models of the printing process have been developed since the 1960's. With a growing need for denser packaging and a drive for higher pin count, screen printing has been refined to yield high resolution prints. However, fine line printing is still considered by industry to be difficult. In order to yield high resolution prints with high first pass yields and manufacturing throughput, the printing process must be controlled stringently. This paper focuses on investigating the effect of manufacturing process parameters on fine line printing through the use of statistical design of experiments (DOE). The process parameters include print speed, squeegee hardness, squeegee pressure, and snap-off distance. Response variables are space widths of 10 mil, 8 mil, and 5 mil lines in both parallel and perpendicular directions relative to the squeegee travel direction. It is concluded that the squeegee hardness and print speed have statistically significant effects on print quality. The harder the squeegee hardness and the lower the print speed within the range of values tested, the better the printed results. It was observed that the space width between perpendicular lines is narrower than that of parallel lines. The implementation procedures of the experimental design are also presented. The analysis of a 2(k) factorial design with center points pertaining to the fine line printing experiment is discussed in detail.