E.U.N.U.C.H. (Cooling)

From: Sipke de Wal <sipke_at_wxs.nl>
Date: Tue Nov 23 13:00:03 1999

The problem with ceramic materials (LIKE BEO) is that it fails in a
britle manner and quite a few miniscule specks of dust may become
airborne when it breaks (like a breaking glass window will often release
small and large fragments).

The main question is wheter you are prepared to take the risk,
for it takes a very tiny amount in your lungs to become a problem.
I Compare it to working with plutonium !!!

Alas, I only wanted to warn those on the list who were not yet informed
on the dangers of berylium-oxide (and metallic beryllium as I gathered
from subsequent treads).


Sipke de Wal

   "He who liveth in a BEO house shall not throw stones"

Robert Garner wrote:
>
> Sipke de Wal,
>
> I passed your concern about Beryllium Oxide to someone here.
> His response:
>
> The only danger is as mentioned below, dust which does not
> happen by accident. It is necessary to seriously grind or file the hard
> material to create dust. As long as you do not try to machine it or
> file it or break it up there is not problem.
>
> So, assemblers should be warned not to mistreat it, breaking
> grinding or filing it.
>
> When I use it I also use thermal compound to make a good
> thermal connection. This greasy substance also provides
> a measure of added protection because if the BEO were
> accidentally scratched or broken any small particles would
> become mixed into this greasy compound and not become airborne.
>
> It has the properties of:
> 1. a dielectric constant of about 6 for low capacitance
> 2. a very low thermal resistance for cooling
>
> If there is great fear of using it alumina can be substituted:
> 1. dielectric constant of 10
> 2. low thermal resistance but not as good as BEO.
>
> Ron Miller
>
> > -----Original Message-----
> > From: Sipke de Wal [SMTP:sipke_at_wxs.nl]
> > Sent: Thursday, November 18, 1999 10:40 AM
> > To: Discussion re-collecting of classic computers
> > Subject: Re: E.U.N.U.C.H. (Cooling)
> >
> > Beware !!!!!!!!!!!!!!!!!!!
> >
> > Beryllium was mentioned here. Beryllium Oxide was used in the thermal
> > conduction stuff HF-transistors decades ago, but this ceramic stuff can
> > be quite lethal. If it breaks and you inhale a few microns of the dust
> > there off, lungcancer can almost be guarantied within a decade !!!!
> >
> > Stay away from BEO !!!!!
> >
> > Sipke de Wal
> >
> >
> >
> > Hans Franke wrote:
> > >
> > > > At -100 Celsius: Al, 241; Cu, 420, Ag, 432. Interestingly enough, at
> > these low
> > > > temperatures Beryllium is pretty good at 367.
> > >
Received on Tue Nov 23 1999 - 13:00:03 GMT