Franklin,
I believe what Brian is referring to as "a common problem" is the
incompatability of certain solder masks when developing a no-clean process.
There is no drop-in replacement when changing soldering materials and
processes.  As in this case, simply changing fluxes, whether it be from RA
to OA, OA to LR alcohol base or even LR alcohol base to LR water borne,
process parameters and solder mask finishes will require modifications.  In
my experience, the surface tension of the solder as it contacts the PCB is
critical to avoid solder ball formation, thus non-glossy solder masks should
be investigated.  The other critical parameter is the preheat settings to
ensure that the flux is not overcooked or undercooked, again by trial and
error.

Steve Sauer
Manufacturing Engineer
Xetron Corporation

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