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

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