Good Morning Marty,
Unlike typical digital and analog circuit card assemblies, Rf CCAs require
tweaking and fine tuning especially with solder joint geometries.  Rf does
not like bulbous or concave joints -- the preference is to go back in time
and look at the old Mil specs/stds which describe the desired connection
"the soldered connections shall be of a smooth metallic luster, no excess
solder, globules, peaks and the angle formed by the solder to the basis
metal at the periphery and intersecting points of the solder shall be no
greater than 60 degrees".  The acceptance criteria contained in J-STD-001
and IPC-A-610 is not acceptable for some Rf applications -- my experience is
that supplementation of these requirements is necessary.
I suggest you look at the geometry of the "as received" product and compare
that to the "in-house reworked" geometries.  One thought is with the suspect
Xceiver having bottom only terminations -- does this pose a reflow challenge
that your supplier hasn't overcome?  Another thought with the Xceiver --
what are the metallized terminations and surface platings?

Steve Sauer
Manufacturing Engineer
Xetron Corporation
Cincinnati, OH
-----Original Message-----

We are experiencing a concerning variation from board to board in the
performance of our RF product.  We have investigated several causes of the
problem and are currently of the opinion that soldering quality of the
transceiver chip is the most significant contributing factor.

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