Joe, I agree with Jason. I have measured standoffs of first side BGAs on double sided boards and they are indeed a bit bigger, but this in fact is a good thing. You now have longer, more "leggy", more compliant joints. The only reason you would want to tack the corners is if they were literally falling off. Loctite makes an adhesive just for this problem. It has enough give in the cured state that you will not be adding more problems than you are solving. regards, Bev Christian Research in Motion -----Original Message----- From: Jason W. Gregory [mailto:[log in to unmask]] Sent: July 1, 2003 2:24 PM To: [log in to unmask] Subject: Re: [TN] double sided reflows and BGAs I'm confused about the reliability being jeopardized. Underfill encapsulation is a common technique. I wouldn't see a problem with "dotting" the corners with adhesive as long as you don't go overboard and hinder future, possible rework. Jason Gregory SMT Production Supervisor/ Integrated Product Team Leader LaBarge Inc. (918)459-2367 (918)459-2221 fax [log in to unmask] http://www.labarge.com "Macko, Joe @ IEC" <joe.macko To: [log in to unmask] Sent by: TechNet cc: <TechNet@listserv Subject: [TN] double sided reflows and BGAs .ipc.org> 07/01/2003 01:08 PM Please respond to "TechNet E-Mail Forum."; Please respond to "Macko, Joe @ IEC" Hello Tech Netters, New board designs are incorporating BGAs on both sides of the board. During the 2nd side reflow, it appears that some of the larger BGAs installed on the 1st side reflowed which are now upside down are dropping slightly I suspect due to gravity. Dropping in the wrong direction, away from the pwb. Who can shed some info on how to either stop the BGAs from dropping, or apply some type of adhesive to the corners after 1st side reflow to secure the BGA in place? I am worried that securing the corners with an adhesive my later cause a reliability problem since you are now securing the corners to the pwb. thanks joe --------------------------------------------------- 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 ----------------------------------------------------- --------------------------------------------------- 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 -----------------------------------------------------