-----Original Message----- From: Anderson, Greg (IndSys, GEFanuc, NA) [mailto:[log in to unmask]] Sent: Thursday, December 10, 1998 10:30 AM To: 'TechNet E-Mail Forum.'; 'Sharon Polmanteer' Subject: RE: FAB: Plating Pits Dear Ms Polmanteer, When we were building PWBs at GE Fanuc, we occasionally experienced the exact "pits" that you are describing. The primary cause invariably was supersaturation of the copper plating solution with air. The air was induced to the plating tank through the filtration system, and could be very difficult to trace. One thing that made troubleshooting difficult was that it took about 24 hours for the air to come "out of solution"-----just turning off your filters for "a little while" will not make this go away. Try leaving your filtration off overnight, and do not turn it back on until after you have plated a rack to look for pits the next morning (this assumes that you are not using liquid sparging). You may find your problem gone. I must credit the Tech guys at DuPont with this advice as they were the ones who pointed us in this direction initially. They used to have a tech paper on this. . . maybe it is still available. Greg Anderson Advanced Manufacturing Engineer GE Fanuc Automation, N.A. Charlottesville, VA e-mail: [log in to unmask] Hi Greg, Accepting that the filtration system is causing supersaturation of the bath, I need to implement a permanent fix. As a band-aid measure, the platers run the filtration system only for four hours at night. Depending on the operators to run the filtration at certain times, to plate at certain times, etc., won't work here... Troubleshooting the filtration system(s)is the larger problem for me. (I was interested in some comments on polarization though I know it isn't the root cause of this pitting problem). Even with fluid sparging, air can be introduced via the filtration system, right? I had a meeting this morning with a guy who gave me some info on proven successful fluid sparging systems. He is going to send me a copy of the DuPont paper. Thing is, they had fluid sparging on one of the tanks here and removed it because the platers said it was the worst tank and always produced pits & nodules. I don't know what happened here. The third hand historical info we hear from the operators is pretty unreliable. I guess I'm interested in filtration systems. Maybe somebody like Mike Bailey could help me out? I hear he has wonderful experience in this matter. Thanks, Sharon ################################################################ TechNet E-Mail Forum provided as a free service by IPC using LISTSERV 1.8c ################################################################ To subscribe/unsubscribe, send a message to [log in to unmask] with following text in the body: To subscribe: SUBSCRIBE TechNet <your full name> To unsubscribe: SIGNOFF TechNet ################################################################ Please visit IPC's web site (http://www.ipc.org) "On-Line Services" section for additional information. For technical support contact Hugo Scaramuzza at [log in to unmask] or 847-509-9700 ext.312 ################################################################