Relationship between capacitance attenuation and voltage of ceramic capacitors

Ceramic capacitor: A capacitor made of high dielectric constant ceramic as dielectric material. (Ceramic barium titanate-titanium oxide) is squeezed into a round tube, disc or disc as the dielectric, a silver layer is sprayed on the ceramic substrate, and silver is applied to the ceramic as an electrode by the sintering method at high temperature. The surface is coated with protective enamel or epoxy resin encapsulation. There are various shapes, including disc, tube, barrel, drum, round, etc.

JEC Ceramic Capacitors

Ceramic capacitors are widely used in military electronic equipment, system communication equipment, industrial control equipment, automotive electronics, consumer electronics and other fields due to their large capacity, small size, non-polarity, low internal resistance, good heat resistance and corrosion resistance.

The low internal resistance of ceramic capacitors is very helpful for low output ripple and can suppress high-frequency noise, but the capacitance of ceramic capacitors decays under high voltage. Why is this?

The attenuation of ceramic capacitor capacity under high voltage is related to the material properties used in ceramic capacitors.

JEC Ceramic Capacitors

All capacitors are composed of two conductors, which are insulated from each other. When voltage is applied between the two conductors, an electric field is formed between the two conductors. Under the action of the electric field, the dielectric charges between the conductors will gather in the direction of the two conductors. The electric field they form is opposite to the original electric field, and the electric field inside the dielectric becomes weaker. The ratio of the original external electric field to the electric field strength in the dielectric is the relative dielectric constant of the dielectric.

The material used for ceramic capacitors is ceramic with a high dielectric constant. The main component is barium titanate, which has a relative dielectric constant of about 5000 and a relatively high dielectric constant.

Since the dielectric can reduce the intensity of the electric field, it is not easy to be broken down, thus improving the ability of the capacitor to store charge, that is, increasing the capacitance. However, under high voltage, the electric field strength in the dielectric will continue to increase, and the dielectric constant will gradually decrease, which is why the capacity of ceramic capacitors decays under high voltage.