Research on metallic contamination control of PFA injection molded fittings

Abstract

AbstractIn chip manufacturing, ultraclean environment is essential during wet processes such as etching, cleaning, and other stages. The fittings used in the process require corrosion resistance, which are made of perfluoroalkoxy alkanes (PFA) by injection molding. Metallic contamination is one of the major impurities for ultraclean products. This study devotes to decreasing the metallic impurities of the parts and improving the wet processes environment. First, the preliminary experiment explored impurities distribution of the injection molds. By comparing the metallic contamination of the different molds' parts, it is shown that the impurities are evenly distributed. Subsequently, the influence of process parameters, including melt temperature, injection rate, screw speed, and holding pressure, on metallic contamination was investigated through the orthogonal experiment. The results indicate that the injection rate has the greatest impact on metallic contamination, followed by melt temperature. With process optimization, the smallest metallic contamination of 1.077 μg/m2 for pipe joints made of PFA can be achieved, which decreases by 56.3% compared with former results. This research indicates that adjusting parameters is a feasible and effective method to reduce the contamination during injection molding of ultraclean products, which provides another idea for improving the cleanliness of the environment in chip manufacturing.