Explanation of the function of self-healing capacitor

Why should you choose a film capacitor with controlled self-healing?

Catastrophic failures and associated explosions or fires are unacceptable. Just as importantly, service lifetime and predictability for optimizing up-time are critical to the product's success. Film capacitors with controlled self-healing are the ideal solution to these challenges and can be obtained in various sizes and technical specifications.

Are capacitors self-healed?

After such a breakdown, capacitors have normal characteristics and can be considered self-healed. However, the remnants of filaments increase local electric fields in the dielectric, injection of electrons, and post-CCS leakage currents in the parts.

Why do polymer capacitors self-heal?

Self-healing in polymer capacitors is due to (i) thermal destruction of the filaments, (ii) formation of voids in the cathode layers, and (iii) trapping of electrons into states in conductive polymers. Different processes can self-heal capacitors to a different degree and require different times.

Do self-healed capacitors grow at rated voltages?

The filaments in self-healed capacitors continue growing at rated voltages, although at a much lower rate than at pre-breakdown voltages. This growth increases electric fields and leakage currents with time under bias for MnO2 capacitors.

How do electrolytic capacitors work?

Electrolytic capacitors rely on an aluminum oxide dielectric grown on aluminum foil electrodes to form the basic structure. These foils are wound and electrically contacted with an electrolyte-soaked paper separator, as shown in Figure 1. Figure 1: Conventional aluminum electrolytic capacitor. Image courtesy of KYOCERA AVX.

Are tantalum capacitors reliable for scintillation breakdown?

Reliability of tantalum capacitors depends on the efficiency of self-healing that restores parts after breakdown. In this work, different types of polymer and MnO2 cathode capacitors have been tested for scintillation breakdown using a constant current stress (CCS) technique modified to allow detection of amplitudes and duration of current spikes.