Views:0 Author:Site Editor Publish Time: 2018-03-26 Origin:Site
Under the effect of alternating voltage, capacitors do not appear in the form of simple capacitors. Besides capacitance, capacitors also have certain inductance and resistance. When the frequency is low, their influence can not be considered; with the high working frequency, the influence of inductance and resistance can not be ignored, and the capacitor may lose its function when it is serious.
Therefore, we generally use four main parameters to measure the general electrical performance of a chip capacitance: capacitance, loss angle tangent ,Dissipation Factor, Insulation Resistance, Dielectric Withstanding Voltage.
The capacitance represents the capacity to store charges. HP bridge is generally used to test. Why can the ceramic medium in the two-layer parallel metal plate store the charge energy? This is because ceramic dielectric has a special physical property: polarization. From an electrical point of view, ordinary conductors, such as metals and electrolytes, have very little binding force on the surrounding electrons by their atoms and molecules. We call these electrons free electrons (or free charges). Under the effect of electric field, the free electron will move along the direction of electric field force to form electric current. However, in ceramic media, the positive and negative charges in atoms and molecules exist in the form of valence or ionic bonds, which are strongly bound to each other, which we call bound charge. Under the action of electric field, these positive and negative charges can only make the relative displacement on the microscopic scale. Because of the relative displacement of charge, the induced dipole moment is produced in atoms and molecules, which is called polarization. Under the effect of external electric field, the dipole molecule will deflect along the direction of electric field, thus forming the corresponding inductive charge on the surface of ceramic medium. So the charge is stored in the capacitor.