Ted I agree with St. Doug but ther may be some other steps you will find useful. Corrosion products are usually a mixture of soluble salts, like copper chloride, and insoluble ones, like carbonates, oxides and hydroxides, as well as a gunge of the original contamination. The first thing I would do is to immerse the products in a 2 - 3% solution of hydrochloric acid at, say, 40deg C. This will dissolve away the soluble and much of the insoluble corrosion products (a little brushing with a nylon-bristles brush will aid the process). I would then suggest a proprietary neutraliser (of the type used as a rinse-aid after soldering with water-soluble fluxes) containing the disodium salt of EDTA. This will help to chelate any remaining metal salts, especially the relatively insoluble lead ones. Finally, I would give them a saponifier wash, to make sure that all of the original flux residues are removed, followed by a damned good rinse cycle, ending with DI water. At this stage, you can be reasonably sure no corrosion-causing chemistry remains on the assembly and it will be possible to evaluate the damage and whether the assembly is usable/repairable/throw-awayable. Be particularly cautious where there are noble metals: gold-plated kovar leads, for example, are notorious for promoting stress corrosion on bends and I've seen cases where the kovar has been completely eaten away and the component is held on by the gold plating! Oh, BTW, your solder joints will appear matt after this treatment, but this does not matter: they will be perfectly OK from the chemical, metallurgical and mechanical points of view. It is purely a cosmetic dulling. Just as an additional precaution, in view of their history, I think I'd be inclined to give these assemblies a spray of an acrylic conformal coating, but this won't be strictly necessary if they meet the testing that Doug advocates. Brian Ted Tontis wrote: > > We have a number of PWB's that show signs of contamination, > management wants to find out if there is a way to clean the boards. I have > told them once the corrosion starts there is no way to clean the assemblies > and make them dependable enough to cover our warranty. Some of the boards > show slight contamination and some more aggressive, but these have been in a > controlled environment for some time. I feel If we where to send them out in > a industrial environment the corrosion would rapidly increases. These boards > are FR-4 and not conformal coated. Am I correct on this? > > Thank you, > > Ted Tontis C.I.D. > Engage Networks, Inc. > 1320 N. Dr. Martin Luther King Jr. Drive > River Level > Milwaukee, WI 53212 > PH 414-918-4267 > FX 414-273-7601 > > --------------------------------------------------------------------------------- > 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 e-mail to [log in to unmask]: SET Technet NOMAIL > To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest > 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 e-mail to [log in to unmask]: SET Technet NOMAIL To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest 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 ---------------------------------------------------------------------------------