Re burnishing
Some p&P machines have the ability or maybe you could program equivalent of
a [flux/glue] dip operation. The component is picked and before placement is
dipped into a controlled depth flux/adhesive, then placed. The  flux/gloop
tanks are usually in the form of a rotating dish with a doctor blade.
If you substitute the gloop tank with a piece of alumina tile and increase
the rotation speed this will give you a burnishing station.  You might need
to change your pickup tool also, Or you could make something easily enough. 
OR us e the idea on a prep basis, Thick film alumina is readily available
and not expensive, you just need scribe cut 1x1" pieces of 96% 1mm / 40mil.
They would be to all intents and purposes perfectly flat [at the size we are
talking about]. 
This might be something to do to get you out of a hole till you can get
something better in place. I don't see why you should though. If your
supplier says that these parts are easily soldered in the millions, why not
tell him to send you a few of those, preferably of the specification you are
using.
I still don't understand why they are making them with gold based inks and
not regular stuff and gold plating. They must be very expensive, why are you
needing gold? Corrosion testing for Mil, some RF or high conductivity thing?

Best Wishes
 
 
 
Mike

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Julie Silk
Sent: Friday, December 07, 2012 7:43 PM
To: [log in to unmask]
Subject: Re: [TN] Termination finishes, Cu thickness under Ag, Au-Pt-Pd

Getting back to my problem (boy, you guys get sidetracked -- how about
starting a VPR discussion under a new thread??)

Wayne, You seem to be the primary person with hands on experience with
PtPdAu.  I appreciate the recommendation to burnish, but that's not
practical on a surface mount part.  (Maybe a new function could be added to
the pick-and-place machine to swipe the part over sandpaper?).  We are using
paste with SMT, but that's where we're seeing the wetting problem with the
PtPdAu.  We're not on a design that could use gold or welding.  Just trying
to solder these things onto a fairly normal PCB.  May well be these are
intended for attaching on thickfilm, although the manufacturer claims they
are good for soldering (and used by the millions).  We have confirmed that
the problem is wetting, not leaching.  Cleaning with solvent had no effect
on the wetting balance test.  Our CM didn't have anything to burnish them
with (and not enough imagination to find something, or no hardware/auto
supply stores in Malaysia?)

A few things in your post that I didn't understand:
"deliberately use an iron tip that doesn't wet well"??
"overlap must be behind a solder dam"?



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