Tant. Cap VS E. Cap

[victorb]

As I know, tant cap and e. cap are also the selection for high capacitance value under high voltage rating's condition. But due to the principle of e. cap, it requires some liquid inisde itself to provide capacitance. So if the circuit's ambient temperature is high, that may vaporize the liquid and cause the e. cap malfunction.

So I was told that use tant cap if the ambient temperature is always high as tant cap can provide higher reliablility and more durable.

But on ther other hand, I also see some e. cap. marked with long life, or high temperature rating, and some of them are also specified it can work for more than 5k hours under maybe 85degC condition. And I also read for about the same reliability data from some tant cap's datasheet. So can anyone kindly tell / teach me the different characteristic between them and how is their applications.

 

[dlgoff]

Tantalum caps are smaller.

Because the dielectric layer can be very thin (thinner than the similar layer in, for instance, an aluminium electrolytic capacitor), a high capacitance can be achieved in a small volume.

http://en.wikipedia.org/wiki/Tantalum" [Broken]

 

[Averagesupernova]

Tantalum caps also have a very low leakage current. I designed and built several timing circuits using the CMOS version of a 555 with 10 meg resistors and tantalum caps. They time out to about 10 minutes. Timing is not real critical, within 15 seconds or so. They have been in service for over 10 years without any trouble.

 

[Enthalpy]

Did you find any tantalum capacitor for high voltage?

The usual choice is aluminium for high voltages (I mean, 100V+).

And I don't remember tantalum capacitors to work well at high temperatures. Aluminium is less bad there - to be checked in datasheets.

What about niobium capacitors? Are they available now, or still too new?