Metallized Film Capacitors

Since metallized film capacitors are becoming more and more popular, more and more film capacitor manufacturers are specializing in producing metallized film capacitors. Film capacitor usually uses metal foil like aluminum foil as electrodes, and coil with plastic film together. However, there is another film capacitors making method, known as metallized film. Its making method is to coat a layer of very thin metal on the plastic film by vacuum evaporation as electrode. So you can save the thickness of electrode foil, reduce the volume of unit capacity of capacitor. That's why film capacitor is relatively easy to make into capacitor with small size and high capacity, such as common MKP capacitor, short for metallized polypropylene film capacitor, as well as the MKT, short for metallized polyester capacitor.

Thin films used by metallized film capacitors include Poly ethyl ester, polypropylene, and makrolon, etc. In addition to winding type, there is also laminated type. Metallized film capacitor has a so-called Self Healing Action. That means when the tiny parts of electrode causes short circuit because of weak dielectric medium, the electrode metal around short circuit parts will raise larger area of melting, evaporation and recover insulation, making the capacitor reply its own function again according to electrostatic energy of capacitor or the short circuit current at that time.
 

Characteristics of metallized film capacitors:

Because of thickness of metalized film is much less than that of the metal foil, after the winding, the volume of metalized film capacitors is much smaller than that of metal foil capacitors. The greatest advantage of metallized film capacitors is "self-healing" feature. The so-called if the thin film medium causes breakdown circuit due to there is some flaws existing at a certain point under over voltage, and the metalized layer of breakdown point instantly melts, evaporates, and forms a small, metal-free zone under the arcing effect, so that the two pole pieces of the capacitor will insulate from each other again and can continue to work. That greatly enhances the reliability of the capacitor. Analysis from the principle, there should be no short circuit failure modes on metallized film capacitors, while there are a lot of short circuit failures on metal foil capacitors.

www.film-capacitor.net has been one of the best capacitor manufacturers in China, specializing in manufacture of film capacitor and ceramic capacitor since 1993. All our products are SGS, IEC, ISO9001 and RoHS compliant. For film capacitors, Shanrui's capacitor's dielectric materials are polyester film, polypropylene film and the dielectrod is evaporated metal layer or Aluminum foil or Zinc-Aluminum foil. And the construction is wound or stacked.

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