PCB substrate with dielectric constant 30; fact or fiction?

I've been told that there are ceramic based PCB substrates with dielectric constant as high as 30+. I've tried searching for such material without success. Does anybody know if such a substrate exists commercially?

I used one once that was low loss and stable around 50. I think you can get up to the thousands, but they are not very temperature stable up there.

Do you mean ceramic loaded PCB such as TMM10 or hard substrates for thin films?

Here is the latter:

http://www.ultrasource.com/designGui...ub=subMatProps

http://www.dilabs.com/pdfs/Design%20...rch%202006.pdf

The DLI article does indeed list substrates with very high dielectric constant. But what are CD, CG, and NR type substrates?

Probably codes for proprietary mixtures. Probably Barium or Magnesium Titanates and odd-ball mixtures. I had some custom, single layer capacitiors made by Compex and they turned out well.

http://www.compexcorp.com/capacitor_substrates.htm

Perfect, thank you so much.