Distortion in capacitors

[nauta]

Hi

Most hobbyists and techs know about the great article written by Richard Marsh and Walt Jung from back in the 1980s or so, and the update made by Cyril Batement a decade ago, but has anyone tested all the new caps?

We know polypropylene is essentially zero THD, and so is polystyrene. PP is easy to get but PS seems to be rare and only in tiny values.

Polyester aka mylar adds odd-order THD.

Polycarbonate seems to have nearly disappeared and is maybe in between polyester and polypropylene.

Mica is okay.

Ceramic can be okay below quite low pFs and only if N0P or C0G.

What about polyethylene-napthlate or -terapthlate?
polymer caps?
polyphenylene sulfide / sulphide?
silicon dioxide / nitride?
aluminium organic polymer? (probably as bad as standard electrolytics?)

It seems there are a lot more dielectrics to choose from - or not to choose from

 

[alexberg]

There is/was a paper by NSC Bob Pease discussing absorption and other particularities in different dielectrics.
Basically Teflon, PP and NP0 ceramic are the good ones. It all depends on voltage across the capacitors.
In simpler terms you may check dielectric properties.

 

[alexberg]

Bob Pease on Audio Capacitors

 

[alexberg]

Passives Aren’t Really So Passive (Part 1): Capacitors - Application Note - Maxim

 

[alexberg]

https://www.eetimes.com/document.asp?doc_id=1278898.

 

[jackinnj]

Linear Audio, I think it was Volume 12, had a great article using a quadrature rig to measure THD%. Even more precise than Cyril's articles of decades ago.

 

[nauta]

I was actually hoping for new THD tests of these other dielectrics. I guess there are none?

 

[MarcelvdG]

Polyester aka mylar adds odd-order THD.

(...)

What about polyethylene-napthlate or -terapthlate?

Polyethyleneterephtalate = polyester

polyphenylene sulfide / sulphide?

Covered in Cyril Bateman's original series: better than polyester, but not quite as good as polystyrene.

Silicon dioxide and silicon nitride are used for the highest performance capacitors on integrated circuits, so maybe you can find something about them in the Journal of Solid-State Circuits. By the way, the dielectric of a Leyden jar also consists mainly of silicon dioxide.

 

[jazbo8]

Thread moved to Parts.

 

[nauta]

Hi Marcelvdg: That is good info, thanks!

Hi jazbo8: I didn't see a component forum so put it in SS since that is where cap distortion will reveal itself best - or worst?

 

[MarcelvdG]

Ceramic can be okay below quite low pFs and only if N0P or C0G.

NP0 a.k.a. C0G is available up to about 220 nF nowadays as multilayer capacitors (these are usually relatively large SMDs). Old-fashioned single layer capacitors indeed have values no higher than a few hundred pF.

 

[wolf_teeth]

Polycarbonate film is no longer manufactured, so the number is dwindling save for NOS and remaining higher priced new caps.

Wolf