Tantalum electrolytic capacitors are the preferred choice in applications where volumetric efficiency, stable electrical parameters, high reliability, and long service life are primary considerations.
Also, thanks to their spongy structure, tantalum capacitors feature high volumetric efficiency. For instance, standard SMD aluminum electrolytic capacitors have the volumetric efficiency of 11.8 µFV/mm3, whereas tantalum capacitors reach the efficiency of 63 µFV/mm3 and above.
The design of tantalum capacitors is based on the structure of tantalum, which looks a lot like a sponge. Such a structure contains an anode, a cathode and a dielectric. The manufacturing process of this type of capacitor begins with compressing tantalum powder around a tantalum wire and sintering it at high temperature, to create the anode.
The steady-state and dynamic reliability of a tantalum capacitor are influenced by several factors under the control of the circuit design engineer. These factors are voltage derating, ripple current and voltage conditions, maximum operating temperature and circuit impedance.
Surface mount technology tantalum capacitors are increasingly being used in new circuit designs because of their volumetric efficiency, basic reliability and process compatibility. Additionally, they are replacing aluminum electrolytics, which use a wet electrolyte.
It is also of interest that because of the solid nature of the tantalum capacitor’s construction, there is no known wear out mechanism in tantalum capacitors. This paper has been written to provide the user of tantalum capacitors with an idea of the effect of design criteria on the capacitor and the methods used in their production.