The capacitance value of MLCC is determined by the number of dipoles in the dielectric that are aligned at both ends of the electrode when voltage is applied as shown in the figure below. When AC voltage is applied, the capacitance value increases in proportion to the number of dipoles that move (align) according to the AC voltage. the meaning of capacitance is C=Q/V, which represents the amount of electric charge accumulated on the electrode when a voltage is applied to the MLCC.
In the case of C0G, a Class 1 type, there is no change in capacitance even when DC voltage is applied.
However, in the case of Class 2 (X5R, X7R, etc.) type, the capacitance gradually decreases as the DC voltage increases as shown below.
The reason is that when a DC voltage is applied, the dipoles in the dielectric are aligned and fixed according to the direction in which the voltage is applied, thereby reducing the number of dipoles that move to voltage changes (AC voltage) It is proportional to the number of dipoles reacting to AC voltage.) As the applied DC voltage increases, the number of dipoles aligned and fixed increases.
As a result, as the number of dipoles for implementation of capacitance decreases, the capacitance value gradually decreases.
