"Jeff Liebermann" wrote in message
news
"g. beat" @spam protected hath wroth:

"Arfa Daily" wrote in message
...
I'm a bit confused about the talk of not using acid fluxed solders in
electronics.
Just about all conventional solder wires formulated for electronic work,
contain one or more cores of rosin based flux. As far as I am aware,
this
is a fundamentally acidic material when in its activated state, and in
fact its being acidic is how it removes the tarnish and oxidation on the
surfaces to be joined.

It's a question of quantity.

Both acid core and activated rosin flux contains ammonium or zinc
chloride. When heated, these produce hydrogen chloride gas (not
liquid) which disolves the copper, lead, and tin oxides and keeps the
solder joint clean. The metallic oxide is converted to zinc, metal,
and a salt. A detailed explanation can be found at:
http://yarchive.net/metal/soldering_flux.html

The difference is that the typical mildly activated rosin flux
generates hydrochloric acid vapor, not liquid. There's very little
acid in the flux and none in the residue. The bulk of the oxidation
protection is from the abietic acid in the rosin.
http://en.wikipedia.org/wiki/Abietic_acid
This effectively protects the copper from oxidation, but not the lead
or tin. That's what the hydrochloric acid smog from the activated
flux produces.

On the other hand, plumbers acid core flux contains the same ammonium
or zinc chloride, but in much larger quantities. There's plenty of
corrosive hydrochloric acid in the residue. That's the problem. Left
on the board, the acid will corrode everything. Just using such flux
around circuit boards will evaporate the acid, which will condense on
nearby components, and eventually corrode them.



--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

Thank you both - more good stuff on the subject !

Arfa