Process characterization on chemical deflash; leading to the elimination of over-etched leads

Out-of-control situations are usually associated with process deviation, parametric errors, operator actions, environmental factors and other variables that can affect the process or product outcome. In leadframe pretreatment processes, the deflashing acid bath is the process medium. There are several factors that can contribute to the variability of the strength of reaction of the deflashing acid which, if not properly controlled, would lead to over-etched leads. These factors were identified as acid concentration, soaking time, bath temperature and batch size. Given these factors, an experiment was conducted to delve primarily into its corollaries with etch rate as the response. The test of hypothesis is used to determine the interaction relationship of the different variables. From this study, process controls, monitors and contingency measures were developed for the elimination of over-etched leads.