Typical electrical characteristics of tantalum polymer capacitors are then presented. It is emphasized that the only significant electrical performance differences versus MnO2–based capacitors are the desired 2 to 3 times reduction in ESR and an undesired, but manageable increase in DC leakage current.
Such low ESR in combination with high capacitance makes the tantalum polymer capacitor the fastest growing segment of the tantalum capacitor industry. The higher conductivity of the conductive polymer electrolyte improves the high-frequency capacitance of these capacitors.
This is typical for tantalum polymer capacitors from all manufacturers. Tantalum polymer capacitors generally have much higher leakage current than is true for comparable MnO2-based capacitors, and the median value of the distribution is usually closer to the catalog limit for tantalum polymer capacitors than is true for MnO2-based capacitors.
Finished Capacitors in Carrier Tape after Leads are Trimmed and Bent around Bottom Edges (7.3mm X 4.3mm). Manufacturers of tantalum polymer capacitors often make available to their customers typical electrical performance and reliability data. Occasionally, such data can also be found in technical papers.
The reasons for the superior performance of tantalum polymer capacitors on this test are not known with certainty. Some speculate that the polymer cathode coating is less porous than the MnO2 layer and physically blocks migration of silver ions to the dielectric’s surface.
Finally, tantalum polymer capacitors are shown to react to environmental stresses in a generally predictable fashion, but appear to be more robust than MnO2-based capacitors to passive humidity exposure. Some observations are in order regarding the suitability of tantalum polymer capacitors for use in spacecraft.
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Electrolytic capacitors use a chemical feature of some special metals, historically called valve metals, which can form an insulating oxide layer. Applying a positive voltage to the tantalum anode material in an electrolytic bath forms an oxide barrier layer with a thickness proportional to the applied voltage. This oxide layer serves as the dielectric in an electrolytic capacitor. The properties of this oxide layer are compared with those of a niobium electrolytic capacitor oxide l…