It's the zinc in tin (or brass) that causes problems with vaporization, but
only around 10^-3 or 10^-5 torr and lower.  If you have a couple hundred
volts running through the system, you get a very nice lightning display
along the vapor trails!  (Not that I've done this personally.  I've just
heard.)

Ethan

----- Original Message -----
From: "Alan B. Pearce" <A.B.Pearce@RL.AC.UK>
To: <PICLIST@MITVMA.MIT.EDU>
Sent: Monday, September 11, 2000 4:37 AM
Subject: Re: [EE]: Was copper, now Lead?


> >Lead (and tin, for that matter), don't
> >sublime, so the vapor pressure should be fairly low at soldering
> >temperatures (~ 400 C).
>
> I think you will find that tin does sublime to some degree. I have had a
tiny
> bit of experience working on vacuum systems (in this case beamlines for
research
> use) and one of the things to avoid was tin. A typical grounding lug would
be
> sandblasted to bare copper for use in the vacuum because the tin coating
would
> release ions into the vacuum.
>
> This may be more a case of how tin behaves in a vacuum than a real
subliming of
> it, but do be aware it may be a problem.
>
> With regards to lead, I believe one of the effects of a build up of lead
in a
> human, is problems with impotency.
>
> --
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