Dingfeng Capacitor -- Effect of metallized film capacitor capacitance attenuation

Jan 13,2020

Metallized film capacitors are capacitors made of metallized films as electrodes and wound (except for laminated structures). The films used in metallized film capacitors include polyethylene, polypropylene, and polycarbonate. In addition to the winding type, there are also laminated types.


Metallized film capacitors have a self-healing effect. That is to say, if a small part of the electrode causes a short circuit due to the fragile dielectric, the electrode metal surrounding the short circuit part will cause a larger area of ​​melting and evaporation to restore insulation due to the electrostatic energy or short circuit current carried by the capacitor at that time. Return the capacitor to its function. Electrolytic capacitors are filled with electrolyte. Over time, the electrolyte will decrease, which will cause the capacitance to decay. If the capacitor leaks, the capacitance will quickly decay.


With the progress of society, human beings' requirements for electronic products are gradually increasing. All electrical and electronic products placed on the market must be EMC certified in accordance with the requirements. Electronic products are required to work normally in an electromagnetic environment and not to cause electromagnetic interference that other equipment in the environment cannot withstand. Therefore, the suppression of electromagnetic interference capacitors in power supplies has been widely used, such as in microwave ovens, coffee makers, bread makers and so on.

Also controlled by the volume and cost of electronic products, metallized film capacitors are increasingly used in step-down circuits to reduce voltage. Therefore, the application of step-down capacitors is becoming more and more common, such as for LED lighting and hair straighteners. However, in the process of extensively using metallized film capacitors, capacitance attenuation often occurs, causing electronic products to fail to achieve the effect of suppressing the electromagnetic interference of the power supply or to stop working, causing great distress to the end user and affecting the quality of electronic products. Be suspicious. Therefore, it is of great significance to slow down the rate of capacitance attenuation of metallized film capacitors during use.



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