Peter, Have you considered the possibility of the solder resist being damaged during the solder wicking of the pads before placing the replacement package. This can make placing and getting good reflowed devices extremely anoying! Also, might seem like a strange one, but I have seen what looks to be a short on an x-ray which is actually intentional if you look at your gerber files where the two balls are for instance at ground etc ... Regards, Doug McCall PCB Manufacturing Engineer - Eastbourne BOC EDWARDS Marshall Road, Eastbourne, East Sussex, BN22 9BA UK ' +44 (0) 1323 501 147 7 +44 (0) 1323 509 824 * [log in to unmask] BOC Edwards is a part of BOC Limited Registered Office: Chertsey Road, Windlesham, Surrey GU20 6HJ Number 337663-English Register Ultimate holding company: The BOC Group plc -----Original Message----- From: Peter Lee [SMTP:[log in to unmask]] Sent: 09 September 2002 21:16 To: [log in to unmask] Subject: [TN] BGA rework - excessive collapsing Technet, We are having problems replacing 35mm BGA, 1.27mm pitch on a OK industry BGA rework station. The resulting X-ray revealed a solder bridge at one corner. There was some warpage on the BGA but not significant. PCB was reasonably flat. Thermal profiling was done to ensure all temp. were optimum. I did notice the BGA balls collapsing quite a bit (at least half of the ball height) after rework. Anyone has suggestion on how to minimize the chance of bridging? Is it common for BGA of this size? We don't have the capability to paste the board for BGA rework. Rgds, Peter ---------------------------------------------------------------------------- ----- 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/html/forum.htm for additional information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315 ---------------------------------------------------------------------------- ----- _____________________________________________________________________ This e-mail has been scanned for viruses by the WorldCom Internet Managed Scanning Service - powered by MessageLabs. For further information visit http://www.worldcom.com _____________________________________________________________________ This e-mail has been scanned for viruses by the WorldCom Internet Managed Scanning Service - powered by MessageLabs. For further information visit http://www.worldcom.com --------------------------------------------------------------------------------- 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/html/forum.htm for additional information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315 ---------------------------------------------------------------------------------