Well, it is SAC, so it looked ugly to start with, right? I believe it will look even uglier--very grainy with lots of protrusions, but none long enough to bridge the gap between pins. Depending on how the layers in your Polyimide board are held together, your laminate may embrittle drastically. The ENIG, if done perfectly, will survive, but if there is any flaw in the nickel process you will see nice black pad failures. I would be surprised if the solder joints themselves (ignoring the black pad possibility) did not survive, but obviously the extremely large grains they would turn into would be even less capable of accepting some creep than the SAC was originally. Perhaps if you did this in vacuum or in nitrogen it would look a bit nicer when it was done cooking. Wayne Thayer >>> [log in to unmask] 4/18/2007 2:38:04 pm >>> Hi all, Just curious, what would you think that a SAC 305 solder joint on a SOIC that was made on a ENIG finished polyimide board would do after spending 140 - 168 hours at 350 F. ? Just wondering is all... -Steve Gregory- --------------------------------------------------- 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 -----------------------------------------------------