Hi wayne,
      as far as I know, no specs are available to define the limits of NC
flux residue left on solder joints. 
Theoretically no halide should be entrapped in the NC flux residue,so no
problem,  but let's not forget such residues could be moisture absorber and
that could mean a potential reliability issue when blending flux residues
with  moisture (ECM), in such a narrow gap between BGA substrate and pcb..

Gabriele

-----Messaggio originale-----
Da: TechNet [mailto:[log in to unmask]] Per conto di Thayer, Wayne - IS
Inviato: martedì 6 novembre 2012 0.50
A: [log in to unmask]
Oggetto: [TN] Limits on flux residue

Is there a spec somewhere which limits the amount of residue allowed for no
clean processing?  I just saw a board where a BGA was about 70%
"underfilled" by flux residue.  No, this was not a flux/underfill product!
A quick look at JSTD-001 Section 8 didn't seem to have specific guidance on
this condition.

Wayne Thayer

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