Adding flux on top of paste?...Yikes!....O.K., I have done this oftentimes with proto boards that had taken 36 hours or more to build. With quite good success I might add...But then, a proto board doesn't go out into the field. If you are using no-clean, the resulting mess could become a disaster. If you are using water soluble, try a more aggressive paste instead. Ryan Grant -----Original Message----- From: Dave Hornback [mailto:[log in to unmask]] Sent: Thursday, November 21, 2002 9:28 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 -----------------------------------------------------