We recently received a shipment of PCBs where the exposed outer layer laminate has staining that looks like copper. I have a photo - <http://tinyurl.com/yp9za2> http://tinyurl.com/yp9za2 My question is what would cause this? I've never seen it before, but I am thinking something in the Copper plating process. The vendor is telling us it is staining but it is an asthetic issue only. What would cause it? Is it an asthetic issue only? It seems to me if the staining was caused by some plating chemistry, then it would effect the laminate properties, particularly the insulation resistance. Thanks! Kevin Glidden Manufacturing Engineer Luminescent Systems Inc. --------------------------------------------------- Technet Mail List provided as a service by IPC using LISTSERV 15.0 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 -----------------------------------------------------