Joe, I have seen the "it depends" notes...............8-) ........and of course they are correct, the finish, the re-work process, the component being re-worked will all contribute. One thing though - how many times do you need to rework it for your purposes? I have seen load board designs which were purposely build to withstand many (10+) rework operations on BGA's using enig as a finish (here the component could not be socketted for DVT testing purposes). The issue there was actually not the enig, but how to keep the solder resist in place with a BGA design during multiple re-work in the "dog bone" area between the pad and the via. If you need data on that contact me off line. Have a great memorial day weekend Techies............. John John Burke (408) 515 4992 -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of Joe Macko Sent: Friday, May 23, 2008 10:41 AM To: [log in to unmask] Subject: [TN] Methodology for determining the # of reworks ENIG finished solder lands for leaded components can withstand Techs, I am looking for some help / guidance on how to analytically determine the number of times the same leaded component can be replaced on a ENIG finished board before the solder lands located on the PCB have been degraded beyond their capability to provide a solderable class 3 surface (.e., how many times can the ENIG finished solder lands with stand a rework/component remove & replace). I suspect the dissolution rates of nickel and copper come into play however I am not sure how to approach this issue and suspect there are some relatively straightforward formulas out there to accomplish this task. Everyone has a different idea and there are numerous rules of thumb discussed but I would like to try something more analytical (without having to use a supercomputer). Thanks again and everyone enjoy the long weekend. Best Regards, -joe --------------------------------------------------- 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 -----------------------------------------------------