> The saponifier chosen (not all
> created equally) needs to be able to adequately remove the soils involved.
>

I agree with Doug. I've always likened saponification to peeling an
onion down to the core, layer by layer. This was why the famous tests
done by Jim Raby about 20 years ago came out so badly: his cleaning
stage lasted only about 30 seconds and this was VERY insufficient to
"peel off" all the layers of rosin (35% solids RMA flux). However, as
Doug says, all saponifiers are not created equal but there are a number
which are a little more equal than others. I've had very good results
with Loncoterge 446 and Alpha 2110 (I think the numbers are right, but
this is from memory) but both are very aggressive and require the most
careful rinsing, care with amphoteric metals and check the surface
attack of laminates, as well (some badly cured laminates have resulted
in weave exposure). Of the slightly milder ones, the Vigon mentioned
before is excellent.

However, what Doug forgot is that "no-clean" fluxes are not created
equal, either. Some are totally resistant to saponifiers, whereas others
will clean off like a charm (plus all intermediate stages). In other
words, the whole process requires qualification.

My personal view is that "no-clean" fluxes are formulated to be plus or
minus safe, **under specified conditions**, provided that the bare board
and all the components have quasi-zero contamination up to the moment of
fluxing. Cleaning them is therefore not in the design of them and is at
your own risk and peril. Fluxes which are designed to be cleaned are
usually formulated to ease this operation and leaving them on the board
is at your own risk and peril. The window between the two where you can
clean or not clean the same flux is very narrow. After all, a
professional carpenter has his electric drill and his electric rotary
saw as two separate machines: you wouldn't expect him to use a saw
attachment on his drill, would you? Therefore, why should you expect the
same flux to do two entirely different jobs?

Brian

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