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I couldn't find a duplicate-like of this question. I'm also not sure whether this is an electrical engineering question or a physics question.

As most of you noticed when one needs to use larger capacitor values the type of capacitors available to use are polarized capacitors such as tantalum or electrolytic capacitors.

What is the relation between large capacitance and being manufactured polarized? is that the same reason: if we ask why are capacitors with small values are manufactured non-polarized?


marked as duplicate by PeterJ, Bence Kaulics, uint128_t, Daniel Grillo, Autistic Jun 17 '16 at 21:07

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  • \$\begingroup\$ None, its different technologies and just the limitations of it \$\endgroup\$ – PlasmaHH Jun 17 '16 at 14:15
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    \$\begingroup\$ Because some technologies simply can't be manufactured in large capacitances without being physically huge or simply infeasible to manufacture. The technologies with the highest volume-to-capacitance ratios are typically the polarised ones. \$\endgroup\$ – Tom Carpenter Jun 17 '16 at 14:17
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    \$\begingroup\$ Capacitor polarization is never an advantage. You don't manufacture them because you want to, you manufacture them because you have to. \$\endgroup\$ – Ignacio Vazquez-Abrams Jun 17 '16 at 14:22
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    \$\begingroup\$ well, inversely, as non-polarized caps tend to get cheaper to make(namely MLCCs), I see less and less usage of <10uF eletroytic caps (except in ultra cheap stuff) \$\endgroup\$ – Wesley Lee Jun 17 '16 at 14:34
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    \$\begingroup\$ @user16307, what makes you think they can't be manufactured? I'd imagine a MLCC could be made in just about any value but do you think they'd be a market for say a 470uF $500 device? \$\endgroup\$ – PeterJ Jun 17 '16 at 14:46

Capacitance is dependant upon;

(1) the area of the plates,

(2) the inverse thickness of the di-electric or insulator between the plates

(3) the permittivity of the di-electric or insulating layer.

To make large value capacitors which don't require enormous plate size you need to have a very thin insulating layer with high permittivity.

Electrolytic construction requires the capacitor to be polarised to maintain the insulating oxide layer created by action of the electrolyte on the metal.

Reversing the polarisation will destroy the insulation and create a short circuit.

enter image description here

N.B. Unpolarised capacitors can be made with high values but will be be physically larger than their electrolytic companions value for value.

  • \$\begingroup\$ great answer, also thanks that you understood what i was asking \$\endgroup\$ – user16307 Jun 17 '16 at 17:39

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