Zoran, Two things about Au over Ni to note. First of all, over time, Ni will diffuse thru gold (mostly along the grain boundaries) and get onto the surface where it will oxidize. Enough Nickel oxide on the surface can give you solderability problems. A strong flux may help. The time it takes for this to happen depends on the thickness of the gold. I don't have any numbers but 6 months does not seem like a very long time. Secondly, the quality of the gold plating is just as important. If the gold has a lot of porosity, Cu and Ni can diffuse to the surface. Try a Nitric acid vapor test (gold porosity test) to ensure that porosity is not a problem. Hope this helps. Perhaps others can give you some advice on what, if any, flux would work. Regards, Paul Terranova [log in to unmask] Phone: 508-467-3109 FAX: 508-467-6796 DIGITAL's Analytical and Environmental Test Services Lab Digital Equipment Corporation M/S: MRO1-3/D2 200 Forest Street Marlboro, MA 01752 -----Original Message----- From: "MRMTS::MRMTS::MRGATE::\"DASMTS::PMDF::ipc.org::TechNet-request\" "@sandz.mro.dec.com [SMTP:"MRMTS::MRMTS::MRGATE::\"DASMTS::PMDF::ipc.org::TechNet-request\" "@sandz.mro.dec.com] Sent: Wednesday, May 28, 1997 11:45 PM To: Paul Terranova Subject: ASSY:Au/Ni Coated Boards From: NAME: Raich, Zoran <[log in to unmask]@PMDF@INTERNET> To: NAME: [log in to unmask] <[log in to unmask]@PMDF@INTERNET> Dear Technetters We have some printed circuit boards with gold over nickel coating which are experiencing solderability problems, ie very poor wetting. I have heard that this may be due to nickel migration through the gold over time. The boards are approximately 6 Months old. Is there a particular shelf life for this type of coating before we need to dump the boards?. Regards Zoran Raich Process Engineer NetComm (Aus) Ltd (+612) 9878 7394 [log in to unmask] *********************************************************************** **** *************************************************************************** * TechNet mail list is provided as a service by IPC using SmartList v3.05 * *************************************************************************** * To subscribe/unsubscribe send a message <to: [log in to unmask]> * * with <subject: subscribe/unsubscribe> and no text in the body. * *************************************************************************** * If you are having a problem with the IPC TechNet forum please contact * * Dmitriy Sklyar at 847-509-9700 ext. 311 or email at [log in to unmask] * ***************************************************************************