Rob: I don't have a contact but if you are going with the concentrated sulfuric acid(>96%)be sure they are using a post sulfuric dip oxidizer to remove the residual solvated epoxy, typically potassium permanganate/caustic(KMn04/NaOH). Without it you risk holewall pullaway due to weak bonding sites for subsequent catalyzation and electroless Cu deposition. Regards Michael Barmuta Staff Engineer Fluke Corp. Everett WA 425-446-6076 -----Original Message----- From: TechNet [mailto:[log in to unmask]]On Behalf Of Robert Coburn Sent: Thursday, April 21, 2005 5:55 AM To: [log in to unmask] Subject: [TN] Concentrated Sulfuric etchback Hi T'Netters: One of our divisions has a design that requires positive etchback on a four layer PCB (FR4 resin system). The board shop that had previously provided these boards subcontracted to a Plasma service. The etchback does not meet requirements. Does anyone have a contact that can provide a concentrated Sulfuric acid, Ammonium Biflouride etchback? TIA, Regards, Rob --------------------------------------------------- Technet Mail List provided as a 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/contentpage.asp?Pageid=4.3.16 for additional information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100 ext.2815 ----------------------------------------------------- --------------------------------------------------- Technet Mail List provided as a 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/contentpage.asp?Pageid=4.3.16 for additional information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100 ext.2815 -----------------------------------------------------