The medium of a capacitor has a significant hindrance to DC current. However, because there is a layer of gel like material with water on the aluminum film, a very small current called leakage current will be generated when voltage is applied, the oxide film is rebuilt and repaired. Usually, the leakage current increases with the increase of temperature and voltage. Its calculation formula is roughly: I=K × CV。 The unit of leakage current I is μ A. K is a constant. Generally speaking, the higher the capacity of a capacitor, the greater the leakage current. From the formula, it can be inferred that the higher the rated voltage, the greater the leakage current. Therefore, reducing the working voltage can also reduce the leakage current.