Hey Sean, Do these racks have a cover that seals the contacts off from the bath? I've seen impressive rack plating when the contact's cover got stuck open. Electroless plating is designed to put copper on non-conductive surfaces. If you are talking electrolytic plating (panel & pattern) then the racks are completing the circuit somehow. I'd hazard a guess that you'll eventually have to either replace, recoat or just stop using these racks. Once the plated metal is there it'll continue to build up everytime you use them. In the short term, you might try peeling the plated metal off with a non-scratching scrapper or using a strong etch bath between runs (well ventilated area a must). And since that metal isn't getting plated onto the boards it adds to your costs. If this just started happening you might notice your chemistry adds getting bigger. When I first started in this biz ('98) we were still using ancient racks with uncoated wing nuts. Talk about extra plating - up, down and all around. After a week or so the nodules could cut through your gloves easy. It can be a real pain if your hand slips when your scrapping it off. Hans Integrity First - Service Before Self - Excellence in All We Do ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Hans M. Hinners Electronics Engineer Warner Robins - Air Logistics Center (WR-ALC/LUGE) Special Operations Forces System Program Office (SOF - SPO) Gunship Team 226 Cochran Street Robins AFB GA 31098-1622 mailto:[log in to unmask] Com: (478) 926 - 5224 Fax: (478) 926 - 4911 DSN Prefix: 468 -----Original Message----- From: Sean Clinton [mailto:[log in to unmask]] Sent: Thursday, October 25, 2001 4:57 PM To: [log in to unmask] Subject: [TN] Racks plating up Hi All, I have a slight problem that I want to avoid turning into a major costly issue. I have a few plating racks that are starting to be overrun with wild plating ( copper and tin) up the rack away from the contacts in areas that are not supposed to be plating. There are even areas of isolated plated metal surrounded by plastic. Upon inspection, I was able to peel off the plated tin and copper and noticed several layers. I think this is most likely due to multiple plating cycles. The racks are solid copper core with a plastic shrouding. The manufacturer claims that "no rack stripping" is needed. In the universe where I am from, most plastics aren't conductive and don't plate. I understand that once initiated, the plating will propagate in the path of least resistance, but what is causing it? My suspicions include poor rinsing of the racks (conductive salts remaining?) after a plating cycle or conductive carbon (from our Shadow process) getting into scratches in the plastic shrouds and eventually arcing causing this plating, but I haven't been able to confirm or disprove either theory yet. It's not affecting quality, but I don't want to wait until it does. Is there some preventative measure to eliminate the problem that anyone has tried? Thanks, Sean Clinton ---------------------------------------------------------------------------- ----- Technet Mail List provided as a free service by IPC using LISTSERV 1.8d To unsubscribe, send a message to [log in to unmask] with following text in the BODY (NOT the subject field): SIGNOFF Technet To temporarily halt delivery of Technet send the following message: SET Technet NOMAIL Search previous postings at: www.ipc.org > On-Line Resources & Databases > E-mail Archives Please visit IPC web site (http://www.ipc.org/html/forum.htm) for additional information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315 ---------------------------------------------------------------------------- ----- --------------------------------------------------------------------------------- Technet Mail List provided as a free service by IPC using LISTSERV 1.8d To unsubscribe, send a message to [log in to unmask] with following text in the BODY (NOT the subject field): SIGNOFF Technet To temporarily halt delivery of Technet send the following message: SET Technet NOMAIL Search previous postings at: www.ipc.org > On-Line Resources & Databases > E-mail Archives Please visit IPC web site (http://www.ipc.org/html/forum.htm) for additional information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315 ---------------------------------------------------------------------------------