Electrolytic and Tantalum Capacitor Life?

[Bill Bowden]

Capacitor specs seem a little confusing about expected lifetimes. It
seems to depend on various factors of temperature, current, frequency,
etc.

Just as a general rule, how many continuous hours of operation would
you expect from a electrolytic or tantalum capacitor assuming the
charge/discharge cycle is fairly long at maybe 1 cycle per second?

Which will live longer, Electrolytic or Tantalum, and does packaging
make much difference (SMD verses axial leads)?

-Bill

 

[John Larkin]

On Wed, 20 Aug 2008 16:13:26 -0700 (PDT), Bill Bowden
<wrongaddress@att.net> wrote:

Capacitor specs seem a little confusing about expected lifetimes. It
seems to depend on various factors of temperature, current, frequency,
etc.

Just as a general rule, how many continuous hours of operation would
you expect from a electrolytic or tantalum capacitor assuming the
charge/discharge cycle is fairly long at maybe 1 cycle per second?

Which will live longer, Electrolytic or Tantalum, and does packaging
make much difference (SMD verses axial leads)?

-Bill

MnO2 tantalums, the common kind, will last forever if they're not
stressed. High dV/dT (ie, high peak currents) can make them fail
shorted or even explosive.

Aluminum electrolytics slowly lose water through the seals and
eventually lose capacitance, very roughly half in 20 years? Depends on
the construction quality. High temperature accelerates the dryout.

John