Re: gEDA-user: Soldering iron tip turns black

[John Coppens <john@xxxxxxxxxxxx>]

On Fri, 4 Feb 2011 16:42:06 -0500
Rob Butts <r.butts2@xxxxxxxxx> wrote:

>  I have a new tip to my iron and it has turned black and more or
> less reples the solder.  The solder just beads up on the tip and drops off.
> I'm sure we didn't condition the tip right but what's going on when it's
> black and repels the solder?  Is the temp too high?  How can I get it to
> that shiny silver solder sticking to it condition?

I've noticed several replies to this problem, but I'm not sure about
the solutions or causes. I read - quite a while ago - that modern
soldering irons don't use copper as a heat conductor, but rather other
(ceramic?) conductors, that do not accept solder. So, the soldering
point has a fine layer of a metal which _does_ accept solder, deposited
during the manufacturing.

If the point was too hot, this fine layer peels off, and there is no
way to solve the problem afterwards, unless it's just dirt (which it
frequently isn't). The trick with these, more economical, irons is to
switch them to lower power when not in use. The life of the points is
extended impressively this way. I used to have a soldering iron stand,
which opened a microswitch in parallel with a diode. 

This way, the iron was always very near the correct temperature, and
in a few seconds becomes usable.

John


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