My colleague who presented the talk is not able to understand why Magnesium is present on the conformal coated board on one of her test sample. In addition, she found migration of Au ions between traces on the coated board - the channel seems like bridges from the top of the traces and not from the sides. My opinions are as follows and I may be wrong in my deduction as I am not a process gal : 1. Can the presence of Magnesium due to the presence of permanganate used to desmear the drilled hole? If not, what is the possible cause of their presence? 2. The presence of "brush hair from the coating brush" is rule out by the engineer as the image does not correlate to that of a artist brush used for coating. My opinions are: - migration is due to hunidity, mositure and high temperature. - CAF as the test coupon consists of comb patterns that are of 4/4mils, 5/5mils and 6/6mils. With such small spacing, the tendency of CAF when bias is applied can occur. The engineer mentioned that resistance measurement does not flag up such presence before coating. In my opinion, if CAF is to be activated and in such small spacing between traces, the time to coat and after coat (Humiseal IB31) is sufficient to cause CAF with presence of humidity or moisture. Well, the above are just my simple analogy from a non process gal. I hope to hear and learn from you experts out there and sincerely appreciate your feedback. Thanks in adavnce and best regards, Wee Mei --------------------------------------------------- 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 -----------------------------------------------------