[volt-nuts] PCBs with ceramic substrates

[David]

I assume for cost reasons everybody likes to stay as close to FR4 type
materials as possible.  This goes double if you have a qualified FR4
type of material which does not suffer from hook and other problems
which are a good reason to use a better material.

I have noticed that special substrates are more common in older
instruments before good or at least not bad FR4 became available.
Tektronix used polysulfone and then later some other white plastic for
high impedance circuits before they solved the FR4 hook problem and
then later they used ceramic substrates for hybrid type construction
even where they did not have to.

On Thu, 6 Apr 2017 06:38:48 +0200, you wrote:

>Moin,
>
>I recently wondered, why people around voltage metrology hardly
>talk about ceramic substrates (Al2O3, AlN, ...) for PCBs.
>They have surface resistivity that is as high as PTFE, have
>higher thermal conductivity, lower thermal expansion (AlN is
>even pretty close to Si). So, why then does it hardly ever get
>mentioned? Is it the cost of those? Or is there something I am
>missing?
>
>			Attila Kinali