On request. Even 99% IPA has sufficient impure water in it to have a 
finite conductivity. To make up the Contaminometer solutions in a past 
life, I used pro analysi 99.9% reagent grade but I still had to deionise 
it before mixing with water at <0.06 µS-cm (so-called 18 meg water), to 
ensure minimal ionics before packing (note I didn't deionise the 
mixture). Of course, the conductivity rose after packing, in PE 
containers that had been soaked for 24 hours in similar solution, as the 
solution will absorb CO2 like gangbusters.

The upshot is that IPA does contain unspecified ionic impurities which 
will be deposited in small quantities after evaporation. The downshot is 
that I believe these may be harmless in most circumstances with 99% IPA 
or purer.

However, the unspecified contaminants that will be spread over the 
assembly with an IPA wash MAY be sufficiently ionic to be dangerous. IPA 
is NOT a good idea but, if it were to be used, it must be followed by a 
DI water wash and rinse to ensure adequate removal of residual ionics, 
especially when the history of the returned goods is unknown (they may 
have been used near stormy seas or salted roads, for example). As you 
have to wash, anyway, better just to wash with a suitable detergent and 
forget IPA which is flammable (flash point ~12°C), volatile and toxic 
(TWA OEL 400 ppm in many countries).

Brian dixit



Barbara J. Rich wrote:
>   
> 
> I am looking for any information on using compressed air to blow off
> "dust bunnies" on circuit boards coming from the field.
> 
>  
> 
> Barb Rich
> 
> Admin. Support Mfg.
> 
> Sanmina-Sci
> 
> 321 S. Taylor Ave.
> 
> 303-264-2009
> 
>  
> 
> 
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