Tantalum capacitors are polarized capacitors with capacitances between 100 nF and several thousand microfarads (µF).
Tantalum capacitors consist of a metallic anode body embedded in plastic. The dielectric is made of tantalum pentoxide (Ta2O5), which is oxidized in a thin layer on the porous anode and is characterized by a high dielectric strength. This is in excess of 600 V/µm. The dielectric has a permittivity between 20 and 30 and can be applied in minimal thicknesses of only 10 nm. Due to its open-pore surface structure, the anode forms a large area on which an oxide layer only a few hundred nanometers thick is deposited. Therefore, relatively large capacitances can be realized with tantalum capacitors.
Because of their manufacturing process, tantalum capacitors can only be operated in a given polarity. If the polarity is reversed, they are destroyed. The polarity can be recognized by the lengths of the connecting wires; the anode with positive polarity is the longer, the cathode the shorter connecting wire. Tantalum capacitors can be in wound form or in drop form.