A tantalum capacitor consists of a porous tantalum core surrounded by tantalum pentoxide. A tantalum wire is embedded into the core and extends axially from the part. The oxide layer is coated with manganese dioxide, graphite, a silver conductive layer and solder as illustrated in the figure at left.

A capacitor is a device that stores an electrical charge.

Tantalum capacitor can only store a small fraction of a the energy from a power supply. However, it can deliver that charge much faster. The fast response time of the capacitor buffers its circuit from any inconsistency in the distribution of power from the power supply.

A capacitor is analogous to a local water storage tank in a public water system. The capacitor buffers the electronic circuit from any inconsistencies in the supply of power, just as the storage tank buffers the user at the faucet from the vagaries of the larger water distribution system.

Digital circuitry is a series of switches, or transistors, analogous to on/off valves in a fluid system. It delivers current from the distribution system, to control other circuits. High speed performance requires these electronic “valves” to respond rapidly, and so is dependent on the ability to deliver charge rapidly. A nearby capacitor provides the “valve” with a ready supply of charge. This “decouples” it from the longer response time of the power distribution system.

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