8/1/2008 - Tantalum capacitor

Tantalum capacitor are a form of electrolytic capacitor. However, some forms of them are non-polar, containing two capacitors connected in series (negative to negative). In comparison with aluminium electrolytic capacitors, they are for similar capacitance and volume ratings generally more expensive, with lower effective series resistance. They usually have longer life, especially at moderately elevated temperatures. For surface mount devices, they are generally smaller.

Tantalums exploit the tendency of tantalum to form a protective oxide surface layer. They use tantalum powder, pressed into a pellet shape, as one “plate” of the capacitor with the oxide as the dielectric, and an electrolytic solution or conductive solid as the other “plate”. Because the dielectric layer can be very thin (thinner than the similar layer in, for instance, an aluminium electrolytic capacitor), a high capacitance can be achieved in a small volume. Because of the size and weight advantages, Tantalum capacitor are useful in portable telephones, pagers, personal computers, and automotive electronics.