I have seen this, but, the root cause was not as you described. Rather, the cause was excessive time during soak. This excessive time in the soak zone cause the flux to burn off. The flux burn-off then resulted in a condition which allowed the spheres to oxidize. This layer of oxidation then made it difficult to reach liquidus for that new oxide, resulting in insufficiently flowed solder. -Carrie -----Original Message----- From: Black, Paul [mailto:[log in to unmask]] Sent: Thursday, August 21, 2003 3:20 PM To: [log in to unmask] Subject: [TN] Soft solder Has anyone ever run into this issue with solder paste? A year ago, we had some boards with paste that was soft after reflow, to the point that in some cases you could move the leads that were supposedly soldered. The paste manufacturer came in and made some changes to our oven profile, saying that the recipe was not allowing the solder to remain in the liquidus state long enough. We thought the problem was solved but recently had a couple of failed boards returned by a customer and found the problem again. This is a no-clean 63/37 paste. Thank you, Paul Black Manufacturing Engineer Kronos --------------------------------------------------- Technet Mail List provided as a free 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 free 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 -----------------------------------------------------