Improvement of film capacitor

Film capacitors use metal foil as an electrode, which is laminated with a plastic film such as polyethylene, polypropylene, polystyrene, or polycarbonate, and is wound into a cylindrical capacitor after overlapping from both ends. The type of film can be divided into polyethylene capacitor (also called Mylar capacitor), polypropylene capacitor (also called PP capacitor), polystyrene capacitor (also called PS capacitor) and polycarbonate capacitor.

Metallized film capacitors are formed by depositing a metal film on the surface of a polyester film instead of a metal foil as an electrode. Because the thickness of the metallized film layer is much smaller than the thickness of the metal foil, the volume after winding is also much smaller than that of the metal foil capacitor. Metallized film capacitors are self-healing. Self-healing characteristics: If the thin film dielectric has a leak at a certain point and a breakdown short circuit occurs under the action of overvoltage, the metallization layer at the breakdown point can be instantly melted and evaporated under the action of an arc to form a small metal-free area The two pole pieces of the capacitor are re-insulated from each other and can still continue to work, thus greatly improving the reliability of the capacitor operation.

Although metallized film capacitors have great advantages, they also have disadvantages compared to metal foil capacitors:

1. Capacitance stability is not as good as foil capacitors, because metallized capacitors are prone to capacity loss in long-term operating conditions and can reduce capacity after self-healing.

2. The ability to withstand large currents is poor, 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 these shortcomings, our R & D staff keeps researching and summed up several points that can be improved: using double-sided metallized film as electrodes, increasing the thickness of metallized coatings, improving the metal connection process on the end faces, reducing contact resistance, etc.  These are already in the experimental stage. I believe that we will be able to meet customer difficulties shortly, solve these shortcomings, and provide customers with better performance and quality, wider application, and lower unit price of metallized film capacitors.