Tantalum wet capacitors are passive devices that provide capacitive reactance to circuits. They are electrolytic capacitors with a wet electrolyte, an anode and a cathode. They are used over other capacitor types due to superior characteristics including: volumetric efficiency, high reliability, electrical stability over a wide temperature range and long service life. These features make them suited for applications such as military, aerospace, satellites and heavy industrial application fields.

 

Wet tantalum capacitors have on average three times the capacitance by volume than aluminum types due to higher dielectric constant and dielectric strength. Electrolytic tantalum pentoxide contains a dielectric constant of 26, much higher than aluminum oxides 8.4. High dielectric strength allows wet tantalum capacitors to be constructed by extremely thin layers of tantalum pentoxide deposited directly on the capacitor’s electrodes. This is much more efficient than the foil and separator construction found in aluminum capacitors.

 

Tantalum wet capacitors exhibit a self-healing mechanism. Self-healing involves a chemical process that reestablishes the oxide layer (capacitor’s dielectric) when it is weakened. Corruption of the oxide layer leads to capacitor corruption. Tantalum wet capacitors have the lowest leakage current among all electrolytic capacitors. Leakage current is a parasitic current drawn by the capacitor when voltage exists. For example, a low leakage current property makes the capacitor suitable for sample and hold circuits because the capacitor will not discharge itself (through leakage current), and it will hold the charged voltage for long time.

 

Tantalum wet capacitors are in the upper-cost range of electrolytic capacitors. Tantalum capacitors are more expensive than aluminum. Additionally, wet tantalum is more expensive than solid tantalum, and both are not used in everyday life consumer products.