Dry tantalum capacitors

[Moreno]

It seems in a dry Tantalum capacitor a thin (few nanometers) layer of Tantalum oxide separates electron conducting metallic Tantalum and hole conducting semiconductor (typically MO2). How in this case a huge charge leakage through quantum tunneling is prevented? For example Aluminum in normal conditions is also covered with thin layer of Aluminum oxide, but it doesn't prevent us to get electrocuted if we touch live Aluminum wire. Because layer of Aluminum oxide is too thin to prevent quantum tunneling of electrons. Why in Tantalum capacitors it should be different?

Edited June 12, 2019 by Moreno

[Moreno]

I think the same issue, probably, may be related to all the typical electrolytic capacitors.

[Eise]

4 hours ago, Moreno said:

How in this case a huge charge leakage through quantum tunneling is prevented?

By applying low voltage. Every capacitor has a maximum voltage.

4 hours ago, Moreno said:

For example Aluminum in normal conditions is also covered with thin layer of Aluminum oxide, but it doesn't prevent us to get electrocuted if we touch live Aluminum wire.

To electrocute somebody you need a high voltage. High enough to break through the aluminium oxide layer. I think it will even be disrupted, so you do not even need the quantum tunnel effect to explain your execution.

 

[MigL]

Most Tantalum capacitors I've seen were used for decoupling on old computer boards from the 80s, as they are more stable ( and expensive ) than cheap electrolytics.
As such they were only rated for 5 ( or 12 ) volt use.

I'm not even sure of the technology used in current surface mount decoupling capacitors, but the on-board regulation of supply voltage is much more robust in modern computer equipment

[Moreno]

16 hours ago, Eise said:

By applying low voltage. Every capacitor has a maximum voltage.

To electrocute somebody you need a high voltage. High enough to break through the aluminium oxide layer. I think it will even be disrupted, so you do not even need the quantum tunnel effect to explain your execution.

 

And how high voltage suppose to be to make tunneling effect significant? Could you give some links? 

[Eise]

3 hours ago, Moreno said:

And how high voltage suppose to be to make tunneling effect significant?

The higher the energy of the particle, the bigger the chance that it will tunnel through. And higher voltage means higher energy for the particle.

Maybe this diagram helps a little to get the idea:

Now imagine that the particle has more energy (= more voltage), so in the diagram, the wave is higher than the potential barrier. And in your case of aluminium oxide, the voltage is much higher than the potential barrier. So you will not be 'quantum executed' but executed in the old classical way.