Leland

I have a number of clients (medical OEM's, medical subcontractors, Military
manufacters) that have been successfully cleaning a no clean (low solids
flux) on mixed technology boards since 1994 with.  Part of the reason behind
the material choices was to have a process that would build product that
could be processed with and without cleaning depending on the product and
customer requirements.  It only required the engineering and qualification
time to approve one paste, flux and cored solder.  If the soldering could be
achieved with a less aggressive flux and no corrosive activators were left on
the board surface then the second step was to optimize cleaning protocol.

Low solids fluxes are not cleanable with water only (no matter how high the
pressure), but can easily be cleaned with the right saponifier and cleaning
approach.  I have personelly cleaned thousands of no clean assemblies in
rescue cleaning situations and these units are operating well in the field
today.  We have also been unsuccessful at trying to clean units that have set
for 6 months after assembly and the client wanted every minute visible
residue removed and it was not possible.  But during the assembly process it
is very achievable to clean a low solids flux from an assembly with a large
amount of fine pitch and low stand off hardware if you use the right
combination of cleaning techniques.  Such as low pressure flood nozzles,
saponifier with a very low surface tension,  heated wash and rinses at 145 F
and good DI water rinsing.  Please contact me offline for additional
information.

Terry Munson
CSL Inc.
P 765-457-8095
F 765-457-9033

<A HREF="www.Residues.com">www.Residues.com</A>

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