A detailed introduction to thin film capacitors

Thin film capacitors are capacitors with metal foil as electrodes, and plastic films such as polyethylene, polypropylene, polyvinylene, polycarbonate, and so on, which are folded from both ends and wound into a cylindrical structure. The types of plastic film are also called polyethylene tube capacitor (Mylar capacitor), polypropylene capacitor (also called PP capacitor), polystyrene capacitance (PS capacitance) and polycarbonate capacitor.

Thin film capacitors are a kind of excellent capacitors because of their many excellent properties. Its main properties are as follows: no polarity, high insulation impedance, excellent frequency characteristics (wide frequency response, and small dielectric loss). Based on the above advantages, thin film capacitors are widely used in analog circuits. Especially in the intersecting part of the signal, it is necessary to use capacitors with good frequency characteristics and very low dielectric loss in order to ensure that there is not too much distortion when the signal is transmitted. Among all the plastic film capacitors the PP capacitors and PSPS capacitors are the most remarkable. Of course the prices of the two capacitors are also relatively high. However, in recent years, in order to improve the sound quality of sound equipment, the parts and materials used have become more and more advanced. The price is not the most important factor to consider. In recent years, PP capacitors and PS capacitors have been used in the frequency and quantity of audio equipment more and more.

Usually, thin film capacitors are made by using aluminum and other metal foil as electrodes and then winding them together. But there is also a method of making thin film capacitors, called metallized films, in which a thin layer of metal is evaporated on a plastic film as an electrode. This can save the thickness of the electrode foil, reduce the volume of capacitor unit capacity, so thin film capacitors are easier to make into small, large capacitors. Common MKP capacitors, for example, are synonymous with metallized polypropylene film capacitors, while MKT are synonymous with metallized poly (ethylene glycol) capacitors.

The films used in metallized thin film capacitors are polyethyllum, polypropylene, polycarbonate, and so on. In addition to the winding type, there are also stacked types. The metallized film capacitor of this type has a so-called self restoring effect, that is, if the tiny part of the electrode is short-circuited because of the weakness of the electrical boundary, it causes the metal of the electrode around the short-circuit part. Because of the electrostatic energy or short-circuit current of the capacitor at that time, it will cause a larger area of melting and evaporation and restore the insulation, so that the capacitor will return to the role of the capacitor.