Judgment method of film capacitor quality:

1) First of all, look at the appearance. If there is a problem with the appearance, there is probably a problem with the film capacitance.

2) The two legs of the test film should be very high resistance with the multimeter resistance. If there is a capacitance meter, measure whether the capacitance value is consistent with the mark on the housing.

3) Room temperature test performance, including capacity, loss, insulation resistance, withstand voltage, ESR, etc. In particular, we need to test the performance of capacitors.

4) Do simulation life test. There is no problem in normal test performance at room temperature,  it depends on whether the service life can last.

5) Choose a reputable capacitor manufacturer.

6) If the use requirements are  high, you can buy some general-purpose ones  the market,  make a copy machine test by yourself. If you pass the test, you can use them at ease.

7) Film capacitor is a kind of the capacitor which uses metal foil as electrode, overlaps it with the plastic film such as polyethylene, polypropylene, polystyrene  polycarbonate  both ends  then rolls it into a cylinder. According to the type of plastic film, it is also known as polyethylene capacitance, polypropylene capacitance, polystyrene capacitance  polycarbonate capacitance. Thin film capacitor has been a kind of capacitor whose utilization rate has been gradually increased in recent years, so we need to understand the inspection  treatment methods of thin film capacitor.

The working principle of thin film capacitor is the same as that of general capacitor, which is to store electric energy by storing charge on the electrode. Usually, it is used together with inductor to form LC oscillation circuit. The working principle of capacitor is that the charge will be forced to move in the electric field. When there is a medium between conductors, it will block the charge movement  make the charge accumulate on the conductor, resulting in the charge accumulation  storage.