Commander Kinsey wrote:
On Fri, 01 May 2020 01:07:53 +0100, whisky-dave
wrote:

On Thursday, 30 April 2020 20:35:27 UTC+1, Commander Kinsey wrote:
Cost is only 20% higher. Lifetime is many times greater.

Not compared to the types of capacitors check out the data sheets
typically up to 2000 hours.

Anything with only 2000 hours is not fit for sale. That's going back to
the days of the filament lightbulbs.

At the temperature of the surface of the sun,
the lifetime of the capacitor is 0.1 milliseconds.
While you're sitting on the surface of the Sun,
a spherical cow flies by.

At 105C, the capacitor lasts 2,000 hours (as communicated in
some military reliability handbook or similar). The numbers
selected, are intended by the manufacturer to resemble
"classes of applications". Military, industrial, consumer.

At 45C, the capacitor lasts 60,000 hours.
This is the temperature inside your PC, on a particularly
hot summers day. A day so hot, you've stepped out of the
computer room, to go for a swim down at the lake.

The rubber seal on the cheap capacitorss, is rated for a 17 year
lifespan. Which is an issue that "runs in parallel" with
the accelerated life testing curve being communicated above.
If the room is filled with concentrated ozone, the cap
lasts a day or so, before the seal is gone and the cap
now has evaporating electrolyte.

The behavior of the reliability number, follows an Arrhenius
style equation, with suitably extracted empirical constants.
This requires the engineer in the lab doing the measurements,
to own some "curve fit software", because nobody writes
this software for themselves any more. (Although we were taught
how when I went to school. Not that this matters.)

Paul