I would not recommend adding flux to the paste. My experience suggests that you will see solder balls and solder fines after the reflow process. I sounds to me like you should manufacture those last 75 units by installing that comonent after reflow by hand. > -----Original Message----- > From: TechNet [mailto:[log in to unmask]] On Behalf Of Dave Hornback > Sent: Thursday, November 21, 2002 11:28 AM > To: [log in to unmask] > Subject: [TN] SMT component oxidation > > > Hello TechNet folks, I need a little help. We have an SMT RF > duplexor that has a ~20% yield hit due to bad wetting under > the component, we suspect they have slight oxidation. > Because it is an RF component the solder process must be very > consistent. On the units that fail we can remove the > component, add a little flux, then reflow the same component > back onto the board. This fixes nearly all the failures. > The parts are in tape and reel and are not convenient to pre-tin. > > One of our mfg folks suggested we add a little liquid flux on > top of the paste immediately after screening. This is the > last build of this product, just 75 units, so we don't want > to re-engineer the entire process. Has anyone tried > something like this? I'm a little nervous to introduce a > science project at this stage. > > Any advice? Thanks, Dave > > --------------------------------------------------- > 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 -----------------------------------------------------