[sdiy] solder types

[Grant Richter]

> I personally use Kester 331 (organic core) for soldering PC boards.  However,
> you have to be careful with this stuff.  If you go to Kesters website, you
> will
> find that all of their solder fluxes are optional to clean,

It seems like all solder flux may become water sensitive (hydrophilic) after
enough years go by. The mildly activated resin core may begin to absorb
water after 25 years. I successfully fixed some of the old Serge 76 kit
boards by just defluxing them. There was apparently enough leakage to cause
a VCO to drift, they were much better after the boards were defluxed.

Once a senior engineer told me the real purpose of defluxing is so the
solder joints can be properly inspected. But I think it has additional
benefits for critical analog circuits.