Solid tantalum capacitors are a subtype of electrolytic capacitors that utilize the basic three-layer capacitor structure (conductor–dielectric–conductor) in the form of a tantalum anode, tantalum oxide dielectric, and a conductive cathode. Tantalum capacitors are polarized, meaning the applied voltage must remain positive. Application of negative voltage will lead to failure of the capacitor.

Tantalum capacitors have low leakage current. Leakage current is a drawback that is common for all electrolytic capacitors. It is parasitic current drawn by the capacitor when voltage is applied to its terminals, and it is modeled by a resistor connected in parallel with the capacitor. This resistor describes the parasitic effect that the capacitor introduces to the applied voltage. The low leakage current property makes solid tantalum capacitors suitable for applications such as sample and hold circuits. The capacitor won’t discharge itself through leakage current, allowing it to hold the charged voltage for a longer period of time.

Solid tantalum capacitors offer higher stability than aluminum capacitors, meaning that tantalum capacitors tend to keep their properties through a variety of operating conditions, such as thermal stress. The failure modes of tantalum capacitors can be potentially dangerous, so it is advisable to utilize thermal and current limiting circuits to mitigate this risk.

Solid tantalum capacitors are most often used in heavy industrial, medical, military, and aerospace applications.