Generally, I agree with what has been said, but with some reservations.
My initial reactions on reading this thread are:
1) Cleaning a mix of fluxes is dangerous.
2) "Vulcanisation" is a process of reducing linear polymerisation in
latex by forcing a cross linking with the aid of (usually) sulfur or
sulfur compounds (sometimes selenium or tellurium). I think what David
was trying to say was that some fluxes contain dibasic carboxylic acids
that can polymerise to form insoluble molecules under the action of heat
(possibly with tin salts catalysing the reaction). The same acids are
also used for cross-linking polymerisation of some epoxy resins, which I
mention as an aside to show that they readily enter into polymeric
reactions. These are not Doug's "appropriate term would be unreacted
flux" (not often that I disagree with him! :-) ). I hope this
interpretation is what David really meant! :-)
3) This is a record! A second disagreement with Doug :-) . "an in-line
cleaner, which has generally better cleaning". This should read "which
may possibly have...". This is a very dangerous generalisation. Some
in-line cleaners produce disastrous results. Some batch cleaners produce
excellent results (but I agree that many do not!). The big advantage of
batch cleaners is a much greater flexibility (wash time can be
prolonged, the number of rinses etc.). With in-line cleaners, the only
control on wash and rinse times you have is conveyor speed and the wash
time is often inadequate and you cannot even control the number of rinses.

Guess the Mountain Dew hadn't kicked in!

Brian

Macko, Joe @ IEC wrote:

> Fellow Technets,
>
> We are looking at switching to a "batch" type cleaner from our WESTEK
> in-line cleaner for circuit boards.  We outsource all of our board assembly
> so we do not have to worry about cleaning screens, etc..  Our boards are
> densely populated, double sided with multiple BGAs on both sides. We use
> wire form, RMA cored solder for in-house rework and touch up.  Use NC for
> BGA rework.
>
> Looking for some recommendation / comments on what fellow techs are using to
> successfully clean their boards - make, model, etc....  Their seem to be a
> lot of units out there.  Thanks
>
> joe
>
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