As you say, ionic contamination testing detects only ionic species. SIR 
can detect some non-ionic species, as well, which are even slightly 
hygroscopic, because they bond with water vapour molecules. Another test 
that will detect both non-ionic hygroscopic and ionic species under a 
solder mask or conformal coating is the pressure cooker test. I know one 
company that used this on normally uncoated boards. They took a test 
sample board from production and sprayed it with a very thin coating of 
CC from an aerosol spray can and pressure-cooked it, then examining it 
for vesicles. This had the advantage that they could see where the 
contamination was, as well as the severity.

Brian

Blair Hogg wrote:
> A ROSE by any other name would smell as sweet, right SIR?
> 
> Happy Friday, Technetters! As you may have guessed, I've spent a bit of time 
> over the last few days looking over cleanliness testing specs, searching 
> through the archives and what not to get more information on the different 
> types of testing. Now it is time to visit the well of knowledge and see if the 
> Technet gurus can help me along the road to cleanliness enlightenment.
> 
> From what I understand, the ROSE test measure the change in resisitivity / 
> conductivity of a test solvent solution (75% IPA / 25% DI Water) that is 
> rinsed over a board / assembly. This will detect contaminants and provide a 
> relative level of the contamination. However, it will only detect those 
> contaminants that are ionic in nature or will affect the resistivity (is that 
> redundant?). The results are near immediate.
> 
> The SIR test measures the insulation resisitance change that occurs when an 
> assembly is exposed to humidity and voltage, and thus has the capability of 
> detcting the presence of contaminants that may not be ionic, but can cause 
> corrision and / or dendrites to grow. The drawback is that the samples must 
> be exposed to controlled humidity / temperature for a priod of time. 
> 
> Does that sound right? Am I missing anything? 
> 
> Are there any other options?
> 
> Thanks,
> 
> Blair
> 
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