Environmental advantages of the closed-loop, semi-aqueous cleaning process as a CFC replacement

The planned phase-out of CFCs (chlorofluorocarbons) and a heightened environmental awareness have caused many printed wiring board (PWB) assemblers to investigate alternative cleaning technologies. It is noted that semi-aqueous cleaning appears to be the best alternative available because it provides superior performance to CFC-113/methanol and offers ecological advantages. It also presents new technical challenges, such as waste management. Three technologies for treating rinse water-carbon plus ion exchange, advanced oxidation plus ion exchange, and membrane separation-were studied. Data from these studies are presented. To date, membrane separation is the most promising technology due to its excellent performance and cost-effectiveness. Membrane separation technology offers technical advantages over the other two technologies; it removes organics and ionics simultaneously and it handles biphasic rinse water well. In addition to superior performance, membrane separation technology is less expensive to operate than carbon treatment with ion exchange