Properties of thin film capacitors

Film capacitor has many excellent characteristics, so it is an excellent performance capacitor. Its main characteristics are as follows: non-polarity, high insulation impedance, excellent frequency characteristics (wide frequency response), and low dielectric loss. Because of these advantages, FILM capacitors are widely used in analog circuits. In particular, capacitors with good frequency characteristics and very low dielectric loss must be used to ensure that the signal is transmitted without too much distortion in the cross-connected part. Among all plastic film capacitors, polypropylene (PP) capacitors and polystyrene (PS) capacitors have the most remarkable characteristics, of course, the price of these two capacitors is also relatively high. However, in recent years, audio equipment in order to improve the quality of sound, the parts used by the material has become more and more advanced, the price is not the most important factor to consider, so in recent years, PP capacitor and PS capacitor are used in audio equipment frequency and quantity is also more and more high.

Film capacitors are usually made by using aluminum foil as electrode and plastic film, and then winding them together. However, there is another manufacturing method for FILM capacitor, called Metallized film, in which a very thin layer of metal is deposited on the plastic film by vacuum evaporation as the electrode. In this way, the thickness of the electrode foil can be eliminated and the volume of the capacitor per unit capacity can be reduced, so the FILM capacitor is easier to be made into a small capacitor with large capacity. For example, the common MKP Capacitor is the proxy of Metailized Polypropylene Film Capacitor, while MKT is the proxy of Metailized Polyester Capacitor.

Metallized film capacitors use films such as polyethyl ester, polypropylene, polycarbonate, etc. In addition to winding type, there are also laminated type. Metallized film this kind of capacitor has a so-called Self ranging the Action, the assumption of small electrode parts for electrical industry qualitative fragile and cause short circuit, cause a short-circuit parts around the electrode metal, due to the capacitor with the electrostatic energy or short-circuit current, and cause larger fusing and evaporation and restore the insulation, To make a capacitor function as a capacitor again.