We tried pH and found that the pH didn't seem a good indicator of how 
     "used up" the saponifier was.  Point is that a saponifier works by 
     chemically binding to the soil and thus eventually is used up.  pH and 
     acid titration were tried and neither successful.  (Note both worked 
     fine on "new" solutions, but couldn't discriminate between a 10% 
     solution that was "saturated" with rosin and a new 10% solution).  
     Acid titration's problem was the acid used was more "active" than the 
     flux and "stripped" the saponifier from the soil so it would always 
     "found it" even when the wash wasn't active anymore.
     
     Best solution (assuming a reasonably constant product flow) is to 
     determine max. allowable loading by experience (beaker level testing) 
     and then "model" the # PWA or hours you can run between changeouts.  
     (make sure you account for dragout losses and automakeup if used).
     
     In our case our PWA load rate varied widely so our best success was a 
     combination of a) monitoring concentration by refractometer (worked OK 
     on "newer" materials, more sensitive than pH and easier to use than 
     acid titration) combined with a visual comparison to a sample showing 
     maximum allowable flux load that the operators would look at.  Method 
     was to sample the solution in a glass vial (they'd "fish" a sample 
     out), compare by eye with "saturated" sample and if cleaner check 
     saponifier level w/refractometer (for losses due to dragout).  If it 
     was "dirtier" (darker/cloudy) than the max. allowable they'ld dump.  
     If you really like numerical data on "dirtiness", a nephelometer can 
     accomplish this for you.
     
     Call if you have questions.
     
     Jim Maguire
     Senior Principal Engineer
     Boeing Defense & Space Group
     PO Box 3999 M/S 3W-97
     Seattle, WA  98124-2499
     Phone 206-657-9063
     FAX    206-657-8903
     Email:  [log in to unmask]

______________________________ Reply Separator _________________________________
Subject: PWB cleaning help?
Author:  [log in to unmask] at esdigate
Date:    5/14/96 10:34 AM


Could anyone out there provide any information or support to the 
following effort;
     
     
     
 We are trying to monitor the cleaning effectiveness of the water 
wash (2% solution of 2444 rinse aid saponifier) in our Westek cleaner.  
We are using it to clean PWB's that have been soldered using 630-20 
water soluble f
     
lux.
     
 We are measuring the solutions' PH and titration to determine the 
cleaning effectiveness of the water / rinse aid solution.  
     
 Can a relationship be established between the PH and the amount 
of rinse aid (titration) as to the remaining cleaning life of the 
solution? This will be used as an indicator as to when to replace the 
solution in the tank
     
?
     
 Thanks for any information or help on this subject.
     
Terry Huddleston
Teledyne Lewisburg
Lewisburg, TN
PH: (615) 359-4531
FAX: (615) 359-4978