Dielectric coatings

[armagdn03]

I am in the process of trying to create efficient homeade parallel plate capacitors, and have used several of the following for dielectric materials

Polyethelene
Polypropylene
Teflon
acrylic spray

Problem is that most of these have relatively low dielectric constants, making the capacitors have a relatively low capacitance.

I know that alot of ceramics have dielectric constants that are very high indeed, and are used in alot of ceramic plate capacitors.
One dielectric I have been looking at has a K value of 110 and is essentially spray on titanium dioxide. Problem is that the only way to apply this coating is with a plasma arch spray machine, so it needs to be professionally done. I may still go this route, but I would like to know

Has anybody out there had any experiance building high performance parallel plate capacitors? what did you use for a dielectric? Does anybody know where to get sheets of ceramic dielectrics, or sprays? Any information you could give may be useful! thank you all.

[gyulasun]

Hi,

There are printed circuit boards made from FR4 material. It has dielectric constant of around 4.7 and in amateur radio practice it is used by some to make parallel plate capacitors by stacking many layers above (or next to) each other and connecting the plates in the correct order.
There is some measurement info on FR4 material here, go down to about the middle part of this long htm page till "Pad Capacitance" :  http://www.cliftonlaboratories.com/Prototyping.htm

If you are not limited in room/volume for homemade capacitors then FR4 material is practical and relatively cheap and you can make from several tens of microFarad (uF) to a few hundred microFarad value capacitors with several hundred working voltage limit.

Gyula

[armagdn03]

This is a great idea, and Im sure it will come in handy at some point down the road, however In my application I am limmited by the number of plates I can use, mainly two. So my only option for raising capacitance is sheet area, distance and dielectric permitivity.

Thank you for your reply though