ASM-1 problems/solder flux

[Brett Duggan]

You guys must be using water soluble flux solder.  The flux left by rosin 
core solder should not have to be cleaned, even though I suppose it is a 
good idea.

The point is emphasized when you look at the solder side of a 20-year old 
PCB that is still working perfectly and notice the layer of brown crud 
that covers it.  I assume that this is rosin core flux...could someone 
please correct me if I'm wrong?

Brett D

> > Oh yes - clean the circuit board to remove *any* solder flux. When you
> > think it's clean, clean it again!
> > 
> > [Luke:] I've heard people stress this point before. What exactly is the
> > reason for this ?
> 
> Coz otherwise it won't work, doh!   :-)
> 
> No, seriously, seems like solder flux is somewhat conductive, which
> means that you'll get small leaking currnets through the flux between
> points that should not be connected. That is Not Good. Granted, it's
> not very big currents at all, but then again our ears are very
> sensitive to very small differences in, say, pitch, so...
> /Moxie (At least that's what I think)