Yes amd no! If you buy a cleaning machine for lead-free, you will
probably find it's as near as dammit is to swearing to one for SnPb. The
same as the fluxes are essentially similar, perhaps with a tweak here or
there in the formulation. What is different is the increased difficulty
to get a good, clean surface. Because the soldering temperature is
higher, Mr. Arrhenius will tell you that the thermal reactions are more
advanced, so that polymers formed in the residues are that much more
difficult to remove, not to mention that Mr van der Waal will tell you
that hydrogen bonding in the intramolecular spaces caused by going that
much higher than the substrate Tg will be hell to penetrate with
whatever you use for cleaning. Both these gentlemen were Nobel prize
laureates in the first decade of last century!!!

So, the crux of the matter is that cleaning will be harder and you will
require more energy, be it physical, chemical or mechanical, to achieve
the same results. You can therefore use your existing machines butyou
may need to make some adjustments in cycle, temp, composition, etc.,
requiring a requalification of your process. Do NOT expect that Pb-free
is just drop-in as far as cleaning is concerned. It ain't!

Brian

Andre Leclair wrote:
> Morning all
> I have been noticing lately a number of Wash manufactures advertising their
> machines for Lead Free assembly processes.
> Are boards assembled using fluxes designed for the higher reflow temps
> (Wave or SMT) harder to remove with older washes ?? or is this an
> advertising gimic to try and sell new machines??
> We currently have 2 older Westkleen (Triton IV & Formula 3MT) and are
> looking at introducing a lead free line next yr.
>
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