What are the common failure modes of capacitors?

Common and less well known failure modes associated with capacitor manufacture defects, device and product assembly problems, inappropriate specification for the application, and product misuse are discussed for ceramic, aluminium electrolytic, tantalum and thin film capacitors.

What is the failure mode of electrolytic capacitors?

The failure mode of electrolytic capacitors is relatively slow and manifests over periods of months rather than seconds which can be the case with short circuit capacitor failure modes. Therefore condition monitoring may be practical and useful for these components.

What causes a capacitor to fail?

Along with short circuit failure as a result of electrical over stress, open circuit failure resulting from corrosive damage is a relatively common event. The capacitor must be manufactured in a very clean environment to prevent contamination with any ionic species which might promote corrosion of the metal film.

What is the failure mode of a thin film capacitor?

The failure mode of thin film capacitors may be short circuit or open circuit, depending on the dominant failure mechanism. There are only a certain number of electrical breakdown events which can occur within a capacitor before there is a risk of the self-healing process no longer being effective and a short circuit failure mode occurring.

What happens if a capacitor fails in open circuit mode?

The open circuit failure mode results in an almost complete loss of capacitance. The high ESR failure can result in self heating of the capacitor which leads to an increase of internal pressure in the case and loss of electrolyte as the case seal fails and areas local to the capacitor are contaminated with acidic liquid.

Why do metallized film capacitors fail?

Indeed, the major degradation of metallized film capacitors occurs in applications exposed to high humidity environments. The primary failure mechanism of electrolytic capacitors is due to the thermal stress .