Hi Jan:
     
     Please don't take this wrong but why are you brewing your own flux? 
     There are dozens of flux formulations on the market that you could try 
     that have enhanced activity to solve solderability problems (but 
     sometimes at the expense of corrosion problems). Interflux is good 
     stuff but you need only enough to do the job and must get it totally 
     cleaned off. What is the nature of the solderability problems? It 
     sounds like you are preheating the assembly for a very long time or 
     that you have very small vias you are trying to fill. Can you give 
     fill in some more details on the specifics of the solderability 
     problems? Are you using nitrogen? Is the assembly big?
     
     
     Dave Hillman
     Rockwell Collins
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______________________________ Reply Separator _________________________________
Subject: Wave soldering flux problems
Author:  [log in to unmask] at ccmgw1
Date:    7/1/96 6:55 AM


Hi!
     
We're using a SEHO nitrogen wave soldering machine and are experience a 
problem with solderability on boards and components.
Now we are testing a new mix of flux. We're mixing 50% of a no clean 
flux (Interflux IF2005M) and 50% destillated water and an additional 2% 
adipic acid. The theory of this is that the alcohol won't evaporate as 
fast as it does and the flux have more time over the preheater to 
"crawl" into the plated holes. The solderability increased and the 
joints was less crystalized. But the problem was the contamination. It 
also increased from a factor of 0,10 to 0,70. Our standards are below 
0,15.
Has anyone tried anything similar or have any theory why the board 
contamination increased that much? 
We have a theory that it wasn't the acids fault but the board. The 
original flux also have a 2% solidcontent. 
     
/Jan Merstrand 
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 fax: +46 33 179669