Views: 2 Author: Site Editor Publish Time: 2021-09-25 Origin: Site
Film capacitors are electronic components, which are used in many household appliances and have a wide range of applications. Film capacitors are electronic components made of metal foil, polypropylene, polystyrene, and other materials. With many advantages and superior performance, it is now the mainstream capacitor.
Classification of film capacitors
A 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 overlapped from both ends and then wound into a cylindrical structure.According to the type of plastic film, they are called polyethylene capacitors (also known as Mylar capacitors), polypropylene capacitors (also known as PP capacitors), polystyrene capacitors (also known as PS capacitors) and polycarbonate capacitors.
According to the film classification, it can be divided into about four types, namely:
1. Polyester capacitors (also known as Mylar capacitors)
2. Polypropylene capacitors (also known as PP capacitors), CBB belongs to this category
3. Polystyrene capacitors (also known as PS capacitors)
4. Polycarbonate capacitor
The structures of these types of capacitors are roughly similar, similar to those of paper capacitors. Most of them are made of materials such as polystyrene. These types of film capacitors have the characteristics of good stability, small size, large capacity, etc., and are often used as bypass capacitors in circuits.
The pp capacitor and ps capacitor have the best performance among many film capacitors. Of course, pp capacitor and ps capacitor are also the most expensive capacitors among all film capacitors. PP capacitors and ps capacitors are often used in audio equipment, and manufacturers often use two types of capacitors for publicity, which shows the status of pp paper capacitors and ps capacitors in audio equipment.
Film capacitor characteristics
The film capacitor has many excellent characteristics, so it is a kind of capacitor with excellent performance. Its main equivalences are as follows: non-polarity, high insulation resistance, excellent frequency characteristics (wide frequency response), and low dielectric loss.Based on the above advantages, film capacitors are widely used in analog circuits. Especially in the signal cross-connection part, capacitors with good frequency characteristics and extremely low dielectric loss must be used to ensure that the signal will not be too distorted when it is transmitted. Among all the plastic film capacitors, polypropylene (PP) capacitors and polystyrene (PS) capacitors have the most remarkable characteristics. Of course, the prices of these two types of capacitors are relatively high. However, in recent years, in order to improve the sound quality of audio equipment, the parts and materials used have become more and more advanced, and the price is not the most important consideration. Therefore, in recent years, the frequency and quantity of PP capacitors and PS capacitors used in audio equipment are also getting high.
Film capacitor structure
Film capacitors generally refer to film adjustable capacitors, which are made of multilayer aluminum sheets connected together with copper screws to make fixed sheets, and then insulated by film. The adjustable part is made of aluminum sheets connected together by adjusting handles as moving sheets. Then insert it into the mutually insulated stators, and use the screwing of the handle to select and change the capacitance. Generally, it is made into a double, called a polyester film double variable capacitor. There are many other capacitors,both can be equivalent to two mutually insulated metal plates, combined with lead wires.
Structure diagram of film capacitor
Advantages of film capacitors
The main advantages of film capacitors: high insulation resistance and good heat resistance. It has self-healing and non-inductive properties.It has excellent high-frequency insulation performance. The capacitance and loss angle have nothing to do with frequency in a large frequency range, and change little with temperature, while the dielectric strength increases with the increase of temperature, which is difficult for other dielectric materials. High temperature resistance and small absorption coefficient.