An old dielectric constant cheat sheet

Article By : John Dunn

The goal of the cheat sheet is to assist with the use of capacitive sensors to detect the presence or absence of materials in a production environment.

Years ago, a colleague sent this list to me. Sadly, he has since passed away so I have no way to know where this list came from, but let me now pass it on to you.

JD_dielectric-constants (cr)
Figure 1: These values of dielectric constants are for materials that are being manufactured, not for materials being used for constructing capacitors.

The goal here is the use of capacitive sensors to detect the presence or absence of these materials in a production environment. This has nothing at all to do with the construction of electronic components.

For some reason, mica and polypropylene (in green) are included, but this table does omit many materials that are conventionally used for capacitor construction such as polyethylene, polystyrene, polyester, Teflon and vacuum. Some of these materials are unknown to me. I have no idea what they are, but clearly somebody, somewhere does know.

We would certainly NOT try to make capacitors using gasoline or powdered milk as the dielectric. Still, at one time there were such things as wax impregnated paper capacitors. I even have a few of those wax capacitors stashed away someplace.

Because of how they looked, my dad used to call them "frankfurters."

First published by EDN.

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