Hi Joe, Only one corner has a slight warp downward. I had bridging at three corner, so I am not sure how much did the warpage contribute to the bridging. There is soldermask damage on the board, but not at the location where bridgings occured. As I mentioned before, the same board with the same chip going through reflow oven has no bridging. To avoid out gasing, I had the board and chip baked before doing the rework, and it didn't seem to help at all. I agree. Without paste, the standoff height is lower. Since the unit that I am working on is for R&D only, I am not worried about long term reliability. Ted --- "Macko, Joe @ IEC" <[log in to unmask]> wrote: > Ted, > > Is the package warping slightly and the corners > turning downward? Is the > solder mask damaged at the corners due to the > cleaning process? Also, > sometimes I have noticed that BGA replacement using > a hot air rework station > results in a lower package stand off distance if > solder paste is not used > (and possibly due to the slight downward hot air > pressure pushing the > package down). > > joe > > -----Original Message----- > From: Ted Kong [mailto:[log in to unmask]] > Sent: Monday, August 11, 2003 2:54 PM > To: [log in to unmask] > Subject: [TN] BGA bridging on corner pins only > > > Hi All at Technet Land, > > Can someone explan why do I see bridgings only on > the > corner pins during rework? The package is a 1517 > Pin > BGA and the rework was done on the SRT rework > station > with only flux (No paste). When I run the same > board > and component through the reflow oven, I see no > bridging. I tried lower the air flow and increase > the > spacing between the board and the chimney, but > neither > helped. Any input is greatly appreciated. > > Thanks all in advance. > > Ted Kong > > __________________________________ > Do you Yahoo!? > Yahoo! SiteBuilder - Free, easy-to-use web site > design software > http://sitebuilder.yahoo.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 > ----------------------------------------------------- > > --------------------------------------------------- > 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 > ----------------------------------------------------- > __________________________________ Do you Yahoo!? Yahoo! SiteBuilder - Free, easy-to-use web site design software http://sitebuilder.yahoo.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 -----------------------------------------------------