Aluminum foil capacitor function

How do aluminum foil capacitors work?

A 0.05~0.11 mm thick anode foil and a 0.02~0.05 mm thick cathode foil are continuously etched electrochemically in a chloride solution with an AC or DC current. This enlarges the effective surface area of the aluminum foils to attain smaller capacitor sizes. The process develops aluminum oxide (Al203) to form a capacitor dielectric.

What are aluminium electrolytic capacitors?

Aluminium electrolytic capacitors are (usually) polarized electrolytic capacitors whose anode electrode (+) is made of a pure aluminium foil with an etched surface. The aluminum forms a very thin insulating layer of aluminium oxide by anodization that acts as the dielectric of the capacitor.

Can aluminum foil be used as a capacitor anode?

Only during the late 1930s the hard-rolled aluminum foil was found to be able to provide capacitor anodes of improved capacitance. This property had not found any use until the 1960s when the aluminum electrolytic capacitor first appeared in the electronic industry.

How does aluminum foil increase capacitance?

To obtain higher capacitance, surface area of aluminum foil for electrolytic capacitor increases through the etching process. During the etching process, a DC or AC current is applied to the aluminum foil. This is done in a chloride solution to assist to dissolve the surface.

What is the anode of an aluminum electrolytic capacitor?

The anode of an aluminum electrolytic capacitor is an aluminum foil of extreme purity. The effec-tive surface area of this foil is greatly enlarged (by a factor of up to 200) by electrochemical etch-ing in order to achieve the maximum possible capacitance values.

What is the surface gain of aluminum electrolytic capacitors?

The surface gain for high voltage foils is ca 34 and up to 300 for low voltage foils (Ebel, 2003; JCC -Foil). Aluminum Electrolytic Capacitors are frequently used as DC-Link capacitors in many power electronics applications.