Hi all, We currently process flex circtuits with immersion tin finish. The thickness is specfied on the pcb drawing as 4 millionths minimum. We were seeing PCBs come from our supplier with corrosion on the traces and plating. We screened for this, and allowed those without corrosion through the two-sided SMT process. After washing, we see corrosion on the traces UNDER the solder mask. I have photos if anyone would like. A few questions.. 1) Is there an IPC spec that deals with platings and corrosion? I bought IPC-A-600G, but I don't see what I am looking for in there. 2) Shouldn't the soldermask be preventing air & moisture from getting to the traces? 3) I have read some old Technet postings on immersion tin, and it seems it has known issues with corrosion, shelf life, etc. True? Can someone summarize? Thanks! Kevin Glidden --------------------------------------------------- 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 -----------------------------------------------------