What you see is solder, over a layer of intermetallics, over a layer of Ni, over cu Vladimir -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of Victor Hernandez Sent: Monday, February 25, 2008 3:43 PM To: [log in to unmask] Subject: Re: [TN] Metallurgists, need assistance, closing this one Where do you see signs of a second layer of nickel. I did see to different colors of nickel though one is very thin. See photo: http://stevezeva.homestead.com/files/_1_not_failed_1000x.jpg Victor, -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of Drew meyer Sent: Monday, February 25, 2008 2:03 PM To: [log in to unmask] Subject: Re: [TN] Metallurgists, need assistance, closing this one Vladimir, Not wrong in context. I did not state one important fact. After attempting to remove the gold the PCB manufacturer lays down another layer of nickel. Thus reflow consumes the second gold layer into the solder joint. On an inffectively stripped PCB, after reflow, you have the following. From the pad up to the solder joint. copper, nickel, gold, nickel, intermetallic, solder The gold interface between the nickel layers is very weak and yields at very low levels of stress. Drew --------------------------------------------------- Technet Mail List provided as a service by IPC using LISTSERV 15.0 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 847-615-7100 ext.2815 ----------------------------------------------------- --------------------------------------------------- Technet Mail List provided as a service by IPC using LISTSERV 15.0 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 847-615-7100 ext.2815 ----------------------------------------------------- --------------------------------------------------- Technet Mail List provided as a service by IPC using LISTSERV 15.0 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 847-615-7100 ext.2815 -----------------------------------------------------