Re: circuit board caps

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Jim Lux by way of Terry Fritz <twftesla-at-qwest-dot-net>" <jimlux-at-earthlink-dot-net>

if it's really PTFE, and of high quality, the dielectric strength is quite
good, and what's more, the loss is really low.  200 kv/cm and dielectric
constant of 2.0 is typical for PTFE. loss tangent is less than 0.0002.

If it is PTFE/Glass composite, then it's a bit trickier, because all
composites have lower breakdown strength than the pure materials of which
they are made.  The differences in dielectric constant (epsilon) cause the
e field to be nonuniform, which in turn tends to cause localized breakdown.

Tesla list wrote:
> 
> Original poster: "Janet Johnson by way of Terry Fritz
<twftesla-at-qwest-dot-net>" <jpjmassage-at-earthlink-dot-net>
> 
> Hi,
> Does anyone have an idea of what the dielectric breakdown voltage of PTFE or
> other circuit board materials might be?  I asked a question about this a
while
> ago and then didn't consider it much further but we have a bunch of 10 to 30
> mil thick, 2x3 foot sheets of sample material at work that we haven't
used for
> years.  If the dielectric could handle the voltage I think it would make a
> viable tank cap.  You'd probably still want to encase it in oil and
remove the
> air though.  BTW how could you make a good vacuum seal?  Thanks for any
> ideas...
> 
> JJ - SLC