"Jeff Liebermann" wrote in message
...
On Sun, 4 Dec 2011 14:54:07 -0800 (PST), klem kedidelhopper
wrote:

On Nov 28, 1:48 am, Jeff Liebermann wrote:
On Sun, 27 Nov 2011 19:20:15 -0500, "Tom Del Rosso"

wrote:
Still no industry standard? Which alloy do you like for repair of new
boards?

Pick a solder formulation:
http://en.wikipedia.org/wiki/Solder#Solder_alloys
http://www.farnell.com/datasheets/315929.pdf
For general repair, when I must use RoHS solder, I have several rolls
of 0.031" 96.5% tin, 3.0% silver and 0.5% copper alloy with no clean
flux:
http://www.mcmelectronics.com/product/TENMA-21-1042-/21-1042
http://www.all-spec.com/products/KWLF27565.html
I have no clue if this solder is better or worse than any other type.
I bought a case fairly cheap, and plan to use it until it runs out.
There are cheaper formulations without the silver which might be
useful.

I also use 63% tin, 37% lead solder for older devices. It works MUCH
better than the RoHS stuff. I'll sometimes use it on boards that use
RoHS solder, but only if I suck off the RoHS solder first. Mixing the
two solder types results in a dull dross-like mixture.

I've wondered about this too. Are you saying that every time I do a
component level repair on a board that was built according to RoHS
specs I need to remove all the RoHS solder associated with that/those
components first? That would just about involve everything new that
comes from Europe or Asia wouldn't it? Lenny

Yep. That's about it. If you want to use tin-lead solder, you have
clean off the tin-silver-copper RoHS solder first. Try mixing the
solder for yourself. The resultant dross-like joint should be
obvious.

After some experimentation, I've found that it's not really necessary
to totally remove the RoHS solder. Just clean it up to the point
where it looks like solder plating on the pads.

--
# Jeff Liebermann 150 Felker St #D Santa Cruz CA 95060

Yes, agreed

Arfa