Re: Desoldering: Thin layer of solder left on pads

longjohnstuartmill@xxxxxxxxxxx wrote:

> I've tried 60/40 tin/lead solder and noticed a huge difference
between
> the solder with lead and the stuff without, especially when I was
using
> a 15-watt iron from Radio Shack. That iron could barely melt the
> lead-free stuff. Most of my solder joints looked like crumpled up
tin
> foil.
>
> The main reason I was using lead-free solder was to make it safer
for
> people/pets, because I'm working at home. I'm not sure if that's a
> good reason or not. I just wasn't crazy about having lots of
little
> pieces of lead laying around for unsuspecting critters to walk in
and
> track around the house, or the best way to clean the mess up, so I
> avoided the problem entirely. :)
>
> With that said, I may switch back now, as long as I can keep my work
> area squeaky clean. What sort of steps to you take to keep
everything
> tidy? Just a decent broom? Or do you even worry about it?
>
I do a lot of soldering on the kitchen table and I try to remember to
wipe it clean before making a sandwich there, but I don't worry too
much about it. The lead in 63 37 solder is pretty well locked up in
the alloy as far as absorbing it in the body, compared to lead oxides
used in old paint, etc. I think there is very little risk from
ingesting an occasional tiny solder ball.

Make sure you have a good quality, activated rosin core solder
designed for electrical work. For hand soldering, I have less success

with the no clean solder. The flux just doesn't do as good a job at
helping the solder wet the board and component leads. Never use
plumbing solder paste flux on a circuit board. It leaves a residue
that conducts electricity and corrodes metals it contacts.

If the flux and temperature are right, the joints should have a bright

shine, especially when eutectic alloys are used. These do not go
through a pasty stage (crystals of the excess metal growing in the
eutectic liquid before the freezing temperature is reached) but
solidify very suddenly.

Here is an interesting document on some flux choices:
http://rocky.digikey.com/WebLib/Kester/Web%20Data/285%20RMA%20Solder.pdf

.

Relevant Pages

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