[sdiy] cleaning flux

[David G. Dixon]

100% isopropyl alcohol is difficult to manufacture, because of something
called an "azeotrope" in the water-alcohol phase diagram.  This makes it
impossible to produce higher than a certain purity of alcohol by
distillation.  If one needs pure alcohol, one has to add pure alcohol to the
refined (but slightly impure) alcohol to get the solution above the
azeotrope.  This is expensive, so most alcohol is "azeotropic" or
essentially at the azeotrope composition, which I'm presuming is about 93%
for IA.

At least, that's how I remember it from my chemical engineering classes at
university lo those many years ago!

> I'd try a pharmacy first.  I don't think I've seen 100% isopropyl
> available "over the counter" but my local drugstore has 93% or so,
> which works fine for cleaning flux.  They tend to have distilled water
> also (I recommend reverse osmosis). My preferred tool for getting
> hard-to-remove flux out from between IC pins and such, is a small and
> stiff natural-bristle brush of the sort commonly known as an "acid
> brush."  I trimmed the bristles down very short (1/4" or so) to make
> them as stiff as I wanted.  Here is a link to the type of brush I'm
> describing:
> http://www.parts-express.com/pe/showdetl.cfm?partnumber=360-368