ECIA EIA/ECA-797

EIA/ECA-797 * ANSI APPROVED

Overview

Except for a few surface-mount technology (SMT) aluminumelectrolytic capacitor types with solid electrolyte systems analuminum electrolytic capacitor consists of a wound capacitorelement, impregnated with liquid electrolyte, connected toterminals and sealed in a can. The element is comprised of an anodefoil, paper separators saturated with electrolyte and a cathodefoil. The foils are high-purity aluminum and are etched to increasethe surface area in contact with the electrolyte.

While it may appear that the capacitance is between the twofoils, actually the capacitance is between the anode foil and theelectrolyte. The positive plate is the anode foil; the dielectricis the insulating aluminum oxide on the anode foil; the truenegative plate is the conductive, liquid electrolyte, and thecathode foil merely connects to the electrolyte.

This construction delivers colossal capacitance because etchingthe foils can increase surface area more than 100 times and thealuminum-oxide dielectric is less than a micrometer thick. Thus theresulting capacitor has very large plate area and the plates areawfully close together.

These capacitors routinely offer capacitance values from 0.1 μFto 3 F and voltage ratings from 5 V to 500 V. They are polardevices, having distinct positive and negative terminals, and areoffered in an enormous variety of styles which include molded andcan-style SMT devices, axial- and radial-leaded can styles, snap-interminals styles and large-can, screw-terminal styles.Representative capacitance-voltage combinations include:

a) 330 μF at 100 V, 1000 μF at 50 V and 6800 μF at 10 V for SMTdevices;

b) 100 μF at 450 V, 6,800 μF at 50 V and 10,000 μF at 10 V forminiature-can styles;

c) 1200 μF at 450 V and 39,000 μF at 50 V for snap-in canstyles;

d) 9000 μF at 450 V and 390,000 μF at 50 V for large-canscrew-terminal styles.

Edition:

14

Published:

08/01/2014

ANSI:

ANSI Approved

Number of Pages:

38

File Size:

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