Breakdown voltages in 27 types of virgin and fractured X7R multilayer ceramic capacitors (MLCC) rated to voltages from 6.3 V to 100 V have been measured and analyzed to evaluate the effectiveness of the dielectric withstanding voltage (DWV) testing to screen-out defective parts and get more insight into breakdown specifics of MLCCs with cracks.
As the applied voltage of the capacitor crosses the breakdown value, it behaves like a resistor. The voltage rating of a ceramic capacitor can be related to the dielectric strength or breakdown voltage of the dielectric material.
The breakdown voltage is determined by the characteristics of the materials used in the construction of ceramic capacitors and the presence of defects in the materials. The higher the manufacturing process’s quality, the higher the breakdown voltage – limited by the materials used.
Contrary to low-voltage ceramic capacitors where breakdown voltage is dozens and even hundreds of times greater than the rated voltage , breakdown in tantalum capacitors occurs at voltages that exceed VR only 2 to 3 times . This limits stress voltages for HALT in tantalum capacitors typically to below 2.5 times the rated voltage. ... ...
A high degree of precision and control of process parameters is necessary to keep the scattering of electrical properties for today's very thin ceramic layers within specified limits. The voltage proof of ceramic capacitors is specified as rated voltage (UR).
For most capacitors, a physically conditioned dielectric strength or a breakdown voltage usually could be specified for each dielectric material and thickness. This is not possible with ceramic capacitors.
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All electrical characteristics of ceramic capacitors can be defined and specified by a series equivalent circuit composed out of an idealized capacitance and additional electrical components, which model all losses and inductive parameters of a capacitor. In this series-equivalent circuit the electrical characteristics of a capacitors is defined by