I remeber in an earlier life (service engineer for spectroscopic CCD
cameras, maybe you know the former OMAs from EG&G PAR) we had vacuum
assemblies which were hermetically sealed. Vacuum was necessary to
prevent any condensation inside and on the entrance window, because
the CCD chip was peltier cooled down to -40°C against electrical
noise. The CCD chip inside was soldered on a Polyimide flex which
connected all stuff to a metal-glass sealed connector to the world
outside. I remember we had often vacuum problems, but the reason no.
1 was (as I know) an insufficient quench of the vacuum pipe after
evacuation, no. 2 was the metal-glass connector (about 50 pins!!),
no. 3 was the soldered glass window, no. 4 were some residues from
assembly. We had other assemblies which were not peltier but LN2
cooled, they had additionally activated carbon as cryogenic getter
inside. This getter caught all outgassing, and with these assemblies
we had only problems if the window or the metal-glass connector was
damaged.

I think after some initial outgassing a thin flex PWB with all
prepregs etc. well cured should not be the problem.

Be sure all stuff in the vacuum is well dried and baked before. How
big is the PWB and the vacuum volume in your application? Do you have
the possibility to pump down again if necessary?

On 11 Feb 99 at 19:14, Steve Joures wrote:

> Can anyone recommend a PCB material for high vacuum that will not
> outgas much ? Can anyone recommend a manufacturer that specialises
> in this sort of thing ? (I'm based in Manchester, England) Any
> recommendations for a solder to use ?
>
> Thanks for any help
>
> --------------------------------------------------
> Steve Joures
> Scientific Analysis Instruments Ltd.
> Medlock House, New Elm Road,
> Manchester M3 4JH, England.
> Tel   : +44 (0)161 827 1430
> Fax   : +44 (0)161 827 1435
> EMail : [log in to unmask]
> --------------------------------------------------
-----------------------------------------------
Matthias Mansfeld Elektronik
* Leiterplattenlayout, Bestueckung
Am Langhoelzl 11, 85540 Haar; Tel.: 089/4620 093-7, Fax: -8
Internet: http://www.mansfeld-elektronik.de

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