>In a message dated 96-06-12 18:22:02 EDT, you write:
>
>>What would be a reliable test method for selling the 
>>     No-Clean/Low-Residue flux concept to Mil Customers.  Is 
>>     Ionograph testing best?  Could I get some replys from some 
>>     of you folks who have jumped this hurdle.  Looking for some 
>>     suggestions.  Thanks in advance for the help.
>
>Mr. Hollandsworth,
>
>This is an easy question to ask, but a difficult one to answer, simply
>because there are so many variables to consider.  I'll give it a shot though.
> 
>
>To answer your first question, my opinion is No.  Most low residue fluxes
>have weak organic acid (WOA) activators.  These activators are benign
>insulators on a board surface, but become electrically conductive when
>extracted into an isopropanol / water solution.  You tend to get high
>readings on an Ionograph or similar instruments.  To the uninitiated, the
>high levels are cause for grave concern, and will do more damage than
>assistance.  The amount of applied flux is generally proportional (roughly)
>to the instrument response.  

I agree.  I can get semi-quantitative analyses of no-clean fluxes on
circuit boards with an Ionograph, but the reading is not directly related
electrical reliability in any simple way.  Omegameter and Ionograph readings 
are only useful as process control tool to ensure that approximately 
the same amount of flux residues remain on boards after processing on a day to 
day basis.  Additionally, to use an Ionograph in a semi-quantitative way, the
instrument must be calibrated with the no-clean flux used, which is not so 
simple.  Unlike NaCl, the response of extractive conductive measurement is
not linear with quantity of no-clean flux activator, so a calibration curve 
must be developed for each no-clean flux in question.

Jack Brous wrote a useful and comprehensive white paper 
CIRCUIT BOARD CLEANLINESS MEASUREMENT -- WHAT DOES IT TELL US?  
If I had an ASCII version, I'd post it but I didn't
get it before Jack retired.  If anyone wants a copy, email me.
    
>I would prefer ion chromatography (IPC TM-650,
>method 2.3.28).  It shows what ionic species are present.  It is more
>expensive than an Omegameter run, but you get much more relevent data. 

Only if you don't know what ions are present to begin with. However IC is 
a powerful tool, especially if one doesn't know what ions are present on a 
board.  Again, some some nonionic materials can can be worse than some
ionic materials, and neither ROSE nor IC will detect them.

>Others have gone
>the route of doing a very thorough test battery, including ROSE, IC, HPLC,
>SIR, etc., and challenged the customer to find something wrong with the
>approach.  
>
If one is willing to pay for the testing, this would be a safe approach.
HPLC would detect some the of the nonionic troublemakers IC and ROSE won't.