Tantalum capacitor

A tantalum electrolytic capacitor, a member of the family of electrolytic capacitors, is a polarized capacitor whose anode electrode (+) is made of tantalum on which a very thin insulating oxide layer is formed, which acts as the dielectric of the capacitor. A solid or liquid electrolyte which covers the surface of the oxide layer serves as the second, cathode electrode (−) of the capacitor. Because of its very thin and relatively high permittivity dielectric layer, the tantalum capacitor distinguishes itself from other conventional and electrolytic capacitors in having high capacitance per volume (high volumetric efficiency) and lower weight.

Most tantalum capacitors are available as surface-mount devices with a solid manganese dioxide or solid polymer electrolyte. A solid electrolyte ensures low equivalent series resistance (ESR) and a stable electrical behavior over a broad temperature range. The high specific capacitance of tantalum capacitors makes them particularly suitable for passing or bypassing low-frequency signals up to some mega-hertz and storing large amounts of energy to support the power rails of highly integrated circuits. Especially the SMD version with its small size and weight make tantalum capacitors attractive for flat or small products. However, due to the cost of tantalum ore, tantalum electrolytic capacitors are considerably more expensive than comparable aluminum electrolytic capacitors.

Tantalum capacitors are polarized components. Reverse voltage or ripple currents higher than specified can destroy the dielectric and thus the capacitor. For safe operation of tantalum capacitors, special circuit design rules are specified from the manufacturers.

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