Good morning, I'm experiencing a problem that appears each time I dump and remake the resist stripper chemistry. Resist is Morton 5050 series. Stripper chemistry is the recommended for this resist. The problem is excess copper after etch, massive excess copper. Electrolytic tin(acid tin)is used as the etch resist. Resist/stripper chemistry vendor and tin vendor are pointing at each other. It appears as if the re-made chemistry is attacking the tin, somehow, and is being re-deposited onto the foil copper surface. The tin then protects the copper during etch in ammoniacal etch solution. There are 2 chemistry sumps on the stripper. When this problem appears it is generally 'solved' by mixing the new sump with the used sump and processing as normal. Also, we have on occasion not mixed the sumps and the problem goes away in a few hectic hair graying days. There are several theories floating around here at our shop but I would like to hold them in reserve so as not to prejudice anyone's opinions. All help is greatly appreciated. Russell ps- I know this is considered the easiest process to operate in the entire shop, but it is eluding all of our efforts to date. Perhaps I/we are too close to it to recognize a basic flaw in the current process. _________________________________________________________________ Protect your PC - get McAfee.com VirusScan Online http://clinic.mcafee.com/clinic/ibuy/campaign.asp?cid=3963 --------------------------------------------------- Technet Mail List provided as a free service by IPC using LISTSERV 1.8e 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 or (re-start) delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL or (MAIL) To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest Search the archives of previous posts at: http://listserv.ipc.org/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 -----------------------------------------------------