SPC and setup analysis for screen printed thick films

Some key process variables that affect the repeatability of the screen printing process for thick-film circuits, and therefore the quality of the final product, are discussed. The discussion of major screen printing problem areas is intended to provide more insight into the complexity of the process and interrelationship among the process variables. The interrelationships of the key variables and their relative importance to process quality and performance are analyzed using a statistical process control technique, namely, statistical design of experiments. For the purpose of an illustration, the fractional factorial design is used. The setting up of a screen printer is a manual operation. The setup involves multiple adaptive trials, before an acceptable product is obtained. This has an adverse effect on the production, and results in delivery delays of the final product to the customers