I don't have any personal experience with this, but I've read about it. Do a Google search using the terms BGA and "ball drop" and you'll turn up some articles that speculate on root cause and cure. Scott Post Staff Manufacturing Engineer P.O.U. 0000-001E-0CTC 2151 E. Lincoln Road Kokomo, Indiana 46904-9005 765-451-2983 (Phone) 765-451-0287 (FAX) -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of Julie Silk Sent: Thursday, June 30, 2011 6:05 PM To: [log in to unmask] Subject: [TN] BGA ball dewet from substrate We have a failure analysis of "dewet" for a BGA ball that is separated from the component substrate. Does anyone know more about this failure mode? The part goes through reflow twice, so once while upside down. It seems unusual, even unlikely, for separation to occur between the balls and the substrate due to the weight of the part rather than between the ball and the PCB. Other parts on the same board do not have this issue. Do you have any experience with this problem or how to prevent it? Or for the future, how to predict it and thus avoid it? Would vapor phase processing influence the likelihood of this defect? Any help appreciated! --------------------------------------------------- Technet Mail List provided as a service by IPC using LISTSERV 16.0 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 For additional information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100 ext.2815 ----------------------------------------------------- **************************************************************************************** Note: If the reader of this message is not the intended recipient, or an employee or agent responsible for delivering this message to the intended recipient, you are hereby notified that any dissemination, distribution or copying of this communication is strictly prohibited. If you have received this communication in error, please notify us immediately by replying to the message and deleting it from your computer. Thank you. **************************************************************************************** ______________________________________________________________________ This email has been scanned by the MessageLabs Email Security System. For more information please contact helpdesk at x2960 or [log in to unmask] ______________________________________________________________________ --------------------------------------------------- Technet Mail List provided as a service by IPC using LISTSERV 16.0 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 For additional information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100 ext.2815 -----------------------------------------------------