We have just run several ENIG finished board assemblies through a 10 day cycled system-level humidity test for the first time. Our previous experience base has been with HASL'd and/or conformal coated boards. Two issues have come up which we don't fully understand. The first issue is that the boards have a light green to white translucent residue areas which have formed on top of the Au surfaces which were not soldered (via-hole lands). SEM-EDS and FTIR shows these residues contain water and nickel species, perhaps a nickel sulfate or carbonate. Taking a cotton swab with IPA and gently rubbing the residues causes small pieces of Au to flake off revealing a dark surface (perhaps black). It appears that there was a pin hole in the gold and the underlying nickel corroded producing the residue and corroding underneath the "good" gold area. I'm wondering if this corrosion is "normal" for ENIG finished boards in this type of environment? Or do we potentially have some other issue? Any reliability concerns? All the PWBs were built in the same shop at different times. Thanks in advance for your comments. Second issue coming up in a separate email to Technet. Best regards, Gregg Klawson General Dynamics Communication Systems Taunton, Massachusetts, USA mailto:[log in to unmask] The views expressed are the author's and do not necessarily reflect the official position of General Dynamics or any of its subsidiaries. --------------------------------------------------------------------------------- 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 the following message: SET Technet NOMAIL 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 ---------------------------------------------------------------------------------