Explanation of breakdown strength of high voltage ceramic capacitor dielectric

The dielectric strength of a high-voltage ceramic capacitor is the ability of a dielectric material to withstand the action of a high intensity electric field without being subjected to electrical breakdown, usually expressed by volts / Miles or volts / cm / cm / v / cm).

When the external electric field intensity reaches a certain critical value, the electrons in the lattice of the material crystal overcome the restraint of the charge recovery force and emit electrons out of the field, resulting in a sufficient number of free electrons colliding with each other and causing avalanche effect. Then it leads to the breakdown of dielectric with sudden breakdown current, which makes the high-voltage ceramic capacitor fail. In addition, there is another mode of high voltage ceramic capacitor dielectric failure, where the heat generated under high pressure loads reduces the resistivity of the dielectric material to a certain extent if it lasts long enough. Leakage current will be generated in the weakest part of the medium. This model is closely related to temperature, and the dielectric strength decreases with the increase of temperature. The dielectric strength of any insulator decreases due to the existence of physical defects in the microstructure of the material, and, like the insulation resistance, the dielectric strength is closely related to the geometric size. Due to the increase of material volume, the probability of random occurrence of defects increases, so the dielectric strength is inversely proportional to the thickness of the dielectric layer.