Ok, thanks for the info. No clear cut answers but I guess PCB finish doesn't make that much difference. Can anyone tell me if lead free solders perform better in corrosive environments? Thanks, Eric Christison Msc Mechanical Engineer Consumer & Micro Group - Imaging Division STMicroelectronics 33 Pinkhill Edinburgh EH12 7BF UK Tel: +44 (0) 131 336 6165 Fax: +44 (0) 131 336 6001 -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of David D. Hillman Sent: Tuesday, May 04, 2004 3:48 PM To: [log in to unmask] Subject: Re: [TN] Corrosion resistance of Ni/Au plating Hi folks! Some additional data - we (e.g. the industry technoweinees) are much too quick to jump to the conclusion that we have a galvanic compatibility problem when using either immersion gold or immersion silver pwb finishes. Rockwell Collins published a paper at the 2003 IPC Fall meeting which demonstrated that the galvanic impact was secondary to a standard corrosion reaction in a salt fog test - i.e. our tin/lead test samples which were in a galvanically happy couple situation underwent healthy corrosion. The galvanic compatibility tables are very important and should not be ignored but they also can be misleading depending on the environment/configuration. Collins has a follow up immersion silver, immersion gold, immersion tin, and tin/lead galvanic corrosion study in progress and will report the results sometime in early 2005. Dave Vladimir Igoshev <[log in to unmask] To: [log in to unmask] > cc: Sent by: TechNet Subject: Re: [TN] Corrosion resistance of Ni/Au plating <[log in to unmask]> 05/04/2004 09:19 AM Please respond to "TechNet E-Mail Forum."; Please respond to Vladimir Igoshev Rudy, It's not supposed to be any Au layer left after re-flow. It desolves in solder. Vladimir Sent from my Blackberry Wireless Vladimir Igoshev, 519-888-7465 ext.5283 -----Original Message----- From: Rudy Sedlak <[log in to unmask]> To: [log in to unmask] <[log in to unmask]> Sent: Tue May 04 10:05:27 2004 Subject: Re: [TN] Corrosion resistance of Ni/Au plating Central to this issue is the question of whether the Gold was completely covered by the Tin/Lead solder. I suspect it was not, and if it was not, this would set up a galvanic cell, which would accelerate the attack on the Tin Lead dramatically. Rudy Sedlak RD Chemical Company --------------------------------------------------- --------------------------------------------------- Technet Mail List provided as a 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/contentpage.asp?Pageid=4.3.16 for additional information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315 ----------------------------------------------------- --------------------------------------------------- Technet Mail List provided as a 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/contentpage.asp?Pageid=4.3.16 for additional information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315 -----------------------------------------------------