Reformation and High Voltage Application

For thin dielectrics, which are used for low voltage polymer capacitors, the quality of the dielectric oxide layer can be restored by the reformation or aging process for thicker dielectrics (capacitors with voltage rating of 25 V or higher) the restoration typically fails. The application of an insulating protection layer on the dielectric can help to reduce the degradation of the dielectric by chemical polymerization.  

Although there has been a strong market request to lower the ESR of high voltage solid electrolyte capacitors, the application of polymer electrolyte capacitors has been limited to lower voltages until recently. 

Electrical Properties of Capacitors Made by a Polymer Dispersion and by In Situ Polymerizations 

Comparison of breakdown voltage (BDV) of polymer tantalum capacitors having polymer cathodes made by chemical in situ polymerization (typical range) and by polymer dispersions (experimental data points). Tantalum anodes were anodized at 100 V. 

Model for degradation of high-voltage dielectric oxide layer. Left scheme of model right pinhole painted into SEM picture of broken oxidized Ta particle. 

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