Two points:
1. When working with a client, the halide issue came up. During the last  
revisions of MIL-F-14256 prior to the generation of J-STD-004, we had to address  
this issue. Some of the rosin batches were found to have trace amounts of  
chloride in them, probably due to the composition of the soil in which the pine  
trees (source of rosin) grew. 
Thus the definition of a non-halide/halogen flux came to be one that had no  
added halide/halogen during the formulation process. Since many of the early 
low  residue fluxes contained a few percent of rosin to help the active 
ingredients  cling to the barrel of plated through holes, the terminology was carried 
 forward. 
One would need conversations or comments from working flux formulators to  
elaborate on today's materials.
 
2. Many electronics assemblers were frustrated by the poor solderability of  
components with RMA (mildly activated rosin formulations favored for military  
work) fluxes. A clever formulator made up a flux that was chloride activated 
to  pass all the RMA activity limits, but soldered like a fireball. The way 
this was  accomplished was to formulate in such a manner that the chloride 
activator  kicked bromide off the brominated fire retardant in FR-4 laminate to  
generate a quite active bromide activated flux. 
Such 'stealth' activated fluxes show the importance of qualifying the  entire 
assembled system, as Brian pointed out, since such an apparently 'mild'  flux 
could have left unexpectedly highly activated residues behind that could  
have had a very negative impact on reliability.  

Bill  Kenyon
Global Centre Consulting
3336 Birmingham Drive
Fort Collins, CO  80526
Tel: 970.207.9586   Cell:  970.980.6373

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