Improved thinking of film capacitors

The film capacitor is a capacitor in which a metal foil is used as an electrode, and a plastic film such as polyethylene, polypropylene, polystyrene or polycarbonate is stacked from both ends and then wound into a cylindrical shape. The types of films can be divided into polyethyl capacitors (also known as Mylar capacitors), polypropylene capacitors (also known as PP capacitors), polystyrene capacitors (also known as PS capacitors), and polycarbonate capacitors.

The metallized film capacitor is a metal film deposited on the surface of the polyester film instead of the metal foil as the electrode, because the thickness of the metallized film layer is much smaller than the thickness of the metal foil, so the volume after winding is also larger than that of the metal foil capacitor. The volume is much smaller. The big advantage of metallized film capacitors is the "self-healing" property. The self-healing property is: if the film medium is short-circuited at a certain point and a breakdown short circuit occurs under the action of overvoltage, the metallization layer of the breakdown point can be melted and evaporated instantaneously under the action of the arc to form a small metal-free region. The two pole pieces of the capacitor are insulated from each other and can continue to work, thus greatly improving the reliability of the capacitor operation.

Metallized film capacitors have great advantages, but they have the following two disadvantages compared with metal foil capacitors: First, the capacity stability is not as good as that of foil capacitors, because metallized capacitors are prone to loss of capacity under long-term working conditions. Both self-healing can result in a reduction in capacity. Second, 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 current is weak. In order to improve these shortcomings, our R&D personnel are constantly researching and summing up several directions that can be improved: using double-sided metallized film as electrode, increasing the thickness of metallization coating, improving the metallization process of end face, reducing contact resistance, etc. These have been in the experimental stage. I believe that we will be able to solve the shortcomings in the near future and solve these shortcomings to provide customers with film capacitors and metal film capacitors with better performance, better quality, wider application and lower unit price.