DAWNCAP power electronic film capacitors characteristics and development direction
Film capacitor is also called plastic film capacitor. It uses plastic film as the dielectric.
The common manufacturing method of thin film capacitor is to use aluminum and other metal foils as electrodes and wrap them together after overlapping with plastic film. However, there is another method for manufacturing thin-film capacitors, called metal film capacitors, that is, vacuum evaporation of a thin layer of metal on the plastic film as an electrode. In this way, the thickness of the electrode foil can be omitted, and the volume per unit capacity of the capacitor can be reduced. Therefore, thin film capacitors are easy to be made into small capacitors with large capacity. For example, the common MKP capacitor is the name of metallized polypropylene film capacitor, while MKT is the name of metallized polyethylene capacitor.
The films used in metal film capacitors include polyethylene, polypropylene, polycarbonate, etc. In addition to the winding type, there are also laminated types. The metal film capacitor has the so-called self-healing effect, that is, if a small part of the electrode is short circuited due to the fragile electrical interface, the electrode metal around the short circuited part will restore the insulation due to the melting and evaporation of a large area caused by the electrostatic energy or short-circuit current carried by the capacitor at that time, and restore the function of the metal film capacitor again.
Metal film capacitor is to evaporate a layer of metal film on the surface of polyester film to replace metal foil as electrode. Since the thickness of the metallized film is much smaller than that of the metal foil, the volume after the winding is much smaller than that of the metal foil capacitor. The great advantage of metal film capacitor is its "self-healing" characteristic. The so-called self-healing characteristic of metal film capacitor is that if the film dielectric has defects at a certain point, breakdown and short circuit will occur under the action of overvoltage, and the metallized layer at the breakdown point will melt and evaporate instantly under the action of arc, forming a small metal free zone, so that the two poles of the capacitor can be insulated again and continue to work, thus greatly improving the reliability of the capacitor. From the principle analysis, metallized film capacitors should not have short-circuit fault mode, and metal foil capacitors will have many short-circuit faults. Although metal film capacitors have the above advantages, compared with metal foil capacitors, they also have the following two disadvantages:
Firstly, the capacity stability of metal film capacitor is not as good as that of foil capacitor, because metal film capacitor is prone to capacity loss under long-term working conditions, and the capacity will be reduced after self-healing. Therefore, the metal foil capacitor should be better if it is used in the oscillation circuit that requires high stability of metal film capacitance.
Another major disadvantage is the poor ability to withstand large current, because the metal film capacitance is much thinner than the metal foil, and the ability to carry large current is weak. In order to improve the disadvantages of metal film capacitors, the high current metallized film capacitors were improved in the manufacturing process. The main improvements are as follows:
Metal film capacitors are mainly used in electronics, home appliances, communications, electric power, electrified railways, hybrid electric vehicles, wind power, solar power and other industries. The steady development of these industries has promoted the growth of metal film capacitor market.
With the development of science and technology, the renewal cycle of electronics, home appliances, communications and other industries is becoming shorter and shorter. Metal film capacitor has become an indispensable electronic component to promote the renewal of these industries because of its good electrical performance and high reliability. In the next few years, with the further development of digitalization, informatization and networking, the state will increase investment in power grid construction, electrified railway construction, energy-saving lighting, hybrid electric vehicles, consumer electronics upgrading, etc., and the market demand for metal film capacitors will further show a trend of rapid growth.
According to the statistics of China electronic components industry association, it is expected that the global metal film capacitor market will grow rapidly by 15~20% in the future. The growth of metal film capacitor market will promote the rapid growth of polypropylene electronic film market.
Comentarios