In the cleaning machines I used to make, we had a dosing pump that 
permitted 0-10% IPA added to the open circuit DI rinse water. We 
recommended commercial 99.5% grade, easily and cheaply obtainable in 
Europe. Excellent results.

However, I feel you may be barking up the wrong tree. This does not 
significantly aid drying because the alcohol azeotrope evaporates first, 
leaving just the water. Don't forget that the residual water will be in 
the places where you least want contamination, so you will have the most 
contamination round the solder joints where the capillaries are smallest.

It doesn't matter two hoots what the impurity levels in water or IPA 
are. What counts are the contamination levels on your assembly at the 
end of the day and the nature of these contaminants. It is up to you to 
qualify the reliability of the final product under the conditions of 
use, not to worry about whether Lake Michigan is polluted and with what.

Brian

On 05/02/2012 02:24, Robert Kondner wrote:
> Hi,
>
>
>
> I was reading through the Ellis book on cleaning and I noticed adding IPA to
> water reduces surface tension.
>
>
>
> Neat, I figure that is a simple way to improve a rinse. I was planning on
> final rinse with distilled water so I don't need to bother with blow off as
> much.
>
>
>
> Just for fun I looked into various grades and it looks like dissolved
> materials is about .005% or 39mg / Liter. (1 L = 780gram)
>
>
>
> Hmmmm, That sounds rather high compared to distilled water. I mean Lake
> Michigan is 170 mg/L I think.
>
>      (See:
> http://www.aquapurefilters.com/contaminants/163/total-dissolved-solids.html)
>
>
>
> No one would think twice about dipping a cleaning swap into IPA to clean a
> board. But Lake Michigan water? Holy Cow!
>
>
>
> Did I find the wrong specs on the IPA?
>
>
>
> Bob K.
>
>
>
>
>
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