The chemical porridge resulting is anybody's guess. If you take all the 
"no-clean" formulations available on the market, there are probably 
several hundred chemicals used. Which one(s) are on your device is a 
geat unknown. You suggest there is a chemical reaction with what is in 
your own flux. If this is so, then the big X becomes an even more 
unknown quantity. And of course a "no-clean" flux is difficult to 
remove, especially after aging: it was never designed to be removed, was 
it. Who can tell what bonding has occurred with the substrate?

I'm sorry, you are alone: only you, yourself, can determine empirically 
what will work, unless we can have more precise details including analyses.

Brian

PS How long is a piece of string?

David Tremmel wrote:
> Technetters,
> 
> I have received some microBGAs which I have to reball and they have a
> no-clean flux residue which is difficult to remove.  Also, when it comes in
> contact with our water-soluble flux it creates an acid which is not very
> 'friendly' to the part.
> 
> Would any of the chemical gurus care to edify one of the uneducated ones 
> why
> no-clean flux, when dried and allowed to set for a couple of months is so
> difficult to completely remove and what possible acids or chemicals are
> created when it is combined with water-soluble flux (type ORM1)?
> 
> As always, I appreciate the responses I receive.
> 
> David Tremmel
> Technical Manager
> BT Mexico
> 
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