The staining can be analysed relatively simply and cheaply using an SEM with EDXA (note these instruments aren't particularly inexpensive but there are companies or institutions who will do the work for you for a fee) this will give you a an elemental map. You'll find gold, maybe some nickel and then potentially carbon and/or oxygen perhaps some other elements. From that a chemist or perhaps a metallurgist, knowledgeable in the industry could speculate fairly accurately the nature of your stain and the possibly the source. You can then take it from there. As to contamination vs. solderability, I doubt very much whether any really useful information could be gathered from such a study, since staining is a relatively random occurrence i.e. it doesn't happen to everyone's products at the same time, for the same reasons. Over and above that there isn't that much information on the very diverse flux systems used and their reaction with the 'stain'. A simple study might be available or could be carried out but it would be very, very, specific and of very limited use to anyone other than perhaps a flux formulation chemist looking to develop an understanding of flux activation, over a number of years. I don't know about the effects on keypad performance. Best regards, Andrew Hoggan www.bba-associates.com -----Original Message----- From: TechNet [mailto:[log in to unmask]]On Behalf Of Bev Christian Sent: Thursday, July 12, 2001 11:37 To: [log in to unmask] Subject: [TN] Staining on Gold TechNetters, I have checked the archives and have not been successful in finding sufficient info on the titled subject. Either I have not done a diligent enough search or the info is not there. So, here are my questions. 1) If you were presented with varying amounts of what looks like water stains on immersion gold pads how would you determine its composition? No guesses now, I can do that. I want to know how people have actually done it! Also, I am not referring to "purple plague" but just slightly off color gold. 2) Has anyone ever been able to correlate amount of staining to solderability issues? Or is it a non-issue? 3) Has anyone seen staining cause problems with respect to keypad electrical continuity? regards, Bev Christian Research in Motion ---------------------------------------------------------------------------- ----- 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 ---------------------------------------------------------------------------- ----- --------------------------------------------------------------------------------- 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 ---------------------------------------------------------------------------------