Replacement of Chlorinated Solvents for In-Line Preplate Metal Cleaning with Environmentally Sound Alternatives

richlorotrifluoroethane (CFC-113) T has been widely used to remove machining oils from metals after those metals have been stamped and formed. In many cases, removal of the hydrocarbon machining oils is necessary before the metals can undergo further processing such as electroplating. In other situations, the stamping occurs as the last step in the process and the formed metal parts must be cleaned before packaging and shipping. Because the CFC solvents have been implicated in stratospheric ozone depletion, AT&T has developed a policy that calls for a 50% reduction in emissions by 1991 with eventual discontinuation of emissions in manufacturing processes by 1994. To comply with the corporate goals, alternative methods of metal cleaning must be developed. These methods may involve cleaning techniques that do not depend upon CFCs or processes that do not result in contaminated parts. Previous to this work, CFC-113 was used in the production of circuit board backplane pins in Kansas City. The incoming rolls of CA 725 metal (Cu/ Ni/Sn) alloy were lubricated with machining oils, stamped and immersed in an ultrasonically agitated CFC1 13 bath to remove residual oil in a continuous reel-to-reel operation. The reels of stamped metal were then inspected for physical imperfections, stored for a variable period and sent to the plating shop as needed. The first step in the plating process, also a reel-to-reel operation, was immersion in a caustic cleaning bath to remove residual oil left from the CFC-113 process and subsequent contaminants from the inspection procedures and storage period prior to plating. The parts were rinsed, immersed in an acidic solution for preplate activation, plated with the appropriate metals and finally coated with insertion oil. Cleanliness is very imTable 1. Alternative Cleaners