Hi Rick, Is the concern for moisture entrapment which could cause "pop-corning", or, delaminating of the FR4 substrate, or, BT resin interface material? Perhaps, the attempt could be to automate a pre-reflow bake out process for high moisture content substrates??? As stated, extending soak times to 5 to 10 minutes should be concerning for the flux. Shean Dalton Austin American Technology www.aat-corp.com <http://www.aat-corp.com> -----Original Message----- From: Rick Thompson Sent: 7/1/2004 11:03 PM To: [log in to unmask] Subject: [TN] Long Reflow Soak Times for BGAs? I'm having a philisophical discussion with my boss regarding long reflow soak times to improve soldering under BGA devices. Is there anything to be gained by extending soak times at the 150C level from 60-90 seconds to 5-10 minutes? I've never seen times this extended and am wondering if they make sense in some situations? The boards in question are not terribly difficult, .063" thick, 14 layer, 12x16 inches with maybe a couple thousand components on top. Any comments on this practice? Thanks in advance, Rick Thompson _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ This e-mail and any files transmitted with it are confidential and intended solely for the use of the individual or entity to whom they are addressed. If you have received this e-mail in error please notify the originator of the message. This footer also confirms that this e-mail message has been scanned for the presence of computer viruses. Any views expressed in this message are those of the individual sender, except where the sender specifies and with authority, states them to be the views of SMTEK International Inc. Scanning of this message and addition of this footer is performed by SurfControl E-mail Filter software in conjunction with CA e-trust anti-virus detection software. --------------------------------------------------- Technet Mail List provided as a 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 -----------------------------------------------------