Difference in performance between various temperature coefficient ceramic caps?

Hey there - I was just thinking about TC (Temperature Coefficients) of ceramic capacitors. So the temperature coefficient (ie X7R, NP0, etc.) specifies the low temp, high temp, and max capacitance change. In general, does it affect things like ESR or anything else? For example, would an X7R and a Y5V generally have the same ESR at 25 C? What about the slope of the ESR with respect to temperature?

On a side note - anybody know why values are pretty much always printed on resistors, but pretty much never on capacitors? Strikes me as bizarre.

Reply to
Michael
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I believe that in most cases ESR goes up with temperature. On the high K ones, ESR is also effected by the mechanical stress etc.

Reply to
MooseFET

Actually, I see capacitance codes on SMT caps fairly regularly now. Data sheets list the codes, which are things like A3, meaning (A) 1.0 times (3) 10^3pF.

I think you'll find that the ESR is a stronger function of frequency than of temperature. I'd expect at low frequencies that, to the extent the ESR is determined by the resistance of the metalization, it would follow the temperature coefficient of resistance of the metalization material, typically around half a percent per degree C.

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gives you a hint that capacitor manufacturers can control ESR to some extent by the design of the capacitors.

I have some empirical evidence that suggests the tempco of capacitance of C0G caps depends on the particular batch of dielectric ceramic. I tried heating some with a soldering iron (so they went between room temp and at least 100C) while monitoring the capacitance, and some varied by several PPM/C (perhaps as much as 20ppm/C), while a few changed practically none at all--amazingly stable! The measurements were with an HP-4274A LCR meter at 100kHz, with about one part per

10,000 resolution, thus able to resolve a 100ppm change.

You might be able to get Kemet or AVX to give you more info about ESR vs temperature and vs various dielectrics. I'll bet they know more than they publish in the typical data sheets. There may even be ap notes on it in their archives.

Cheers, Tom

Reply to
Tom Bruhns

That's not my experience. I've found it to slightly decrease with temperature and slightly increase with applied voltage.

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Thanks,
Fred.
Reply to
Fred Bartoli

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