Underhood Temperatures

[bernie at innovative.iinet.net.au]

Byron Smith tapped away at the keyboard with:

> > [ALL of them; that's EVERYTHING that's EVER been under a hood, OK? Oh
> > gawd, I just know someone's gonna point out an exception :];
> > 
> 	Well, as long as you knew it was coming... :)

> 	Actually it's not an underhood exception, just the limit as I've
> seen it.
> 	In the oil industry, down-hole tools are typically rated to 175C
> ambient and
> 	are qualification tested to 180C.  Higher temp tools are in the
> works, with qualification ambients knocking on 200C.  Getting the
> electronics to live in those environments is neither cheap nor easy, as you
> might guess.  Components aren't custom designed, but usually start life in
> the Mil-spec bin and get 100% screened for higher temp operation.

The situation is even worse for space-craft. Heat dissipation is a
problem if all you can rely on is radiation. And there's more to it
than simply coating it black; because direct solar radiation from
a sun would be absorbed very efficiently.

There's a division or subsidiary of IBM (the name of which escapes
me) which develops components for such environments. I vaguely
recall that they had microprocessors operating at over 200C. It's
easy enough to heat the insides of a space probe to a suitable
minimum temperature by using a nuclear source.

Suffice to say that such components are not cheap; and probably why
NASA seems to be purchasing components from Radio Shack for its Mars
probes. :-)

-- 
Bernd Felsche - Innovative Reckoning
Perth, Western Australia
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