Metallized film capacitors are capacitors made of organic plastic film as the medium, metallized film as the electrode, and made by winding (except for the laminated structure). The films used in metallized film capacitors include polyethylene, polyester Acrylic, polycarbonate, etc., in addition to the winding type, there are also laminated types. Among them, polyester film medium and polypropylene film medium are the most widely used.

effect
This type of metallized film capacitor has a so-called self-healing action, that is, if a small part of the electrode is short-circuited due to the fragility of the electrical interface, the electrode metal around the short-circuited part will be damaged. Due to the electrostatic energy or short-circuit current carried by the capacitor at that time, a larger area of melting and evaporation is caused to restore the insulation, so that the capacitor returns to the role of the capacitor again.

Disadvantages and Improvements
  From a theoretical analysis, there should be no short-circuit failure mode for metallized film capacitors, but many short-circuit failures will occur for metal foil capacitors (such as 27-pbxxxx-j0x series). Although metallized film capacitors have the above-mentioned huge advantages, compared with metal foil capacitors, they also have the following two disadvantages: First, the capacity stability is not as good as that of foil capacitors, because metallized capacitors are prone to capacity loss under long-term working conditions And self-healing can lead to a decrease in capacity, so if it is used in an oscillating circuit that requires high capacity stability, it is better to use a metal foil capacitor. Another major disadvantage is the poor ability to withstand large currents. This is because the metallized film layer is much thinner than the metal foil, and the ability to carry large currents is weak. In order to improve the shortcoming of metallized film capacitors, there are currently improved high-current metallized film capacitor products in the manufacturing process. The main improvement methods are:
1) Use double-sided metallized films as electrodes;
2) Increase the thickness of the metallized coating;
3) The metal welding process of the end face is improved to reduce the contact resistance.