Mechanism Underlying Stacking-Layer Effect of Dielectric Properties of Multilayer Ceramic Capacitors

Abstract

The stacking-layer effect in multilayer ceramic capacitors (MLCCs) is a phenomenon in which the dielectric permittivity of dielectric layers increases with increasing number of layers. To elucidate the mechanism underlying this effect, we performed a simulation of residual stress in MLCCs by the finite element method (FEM) as well as dielectric measurements under uniaxial compressive stress. The FEM analysis revealed that tensile stress along the stacking direction was induced in dielectric layers owing to the difference in thermal expansion coefficient between internal electrodes and dielectric layers. The results of dielectric measurements indicated that the shell part in the dielectrics of MLCCs played an important role in the stress dependence of dielectric properties. The mechanism underlying the stacking-layer effect proposed in this study was based on the enhancement of polarization rotations in polar nanoregions in the relaxor by the tensile stress in dielectric layers.

Microstructures and Highly Accelerated Lifetime Test of X5R Type BaTiO₃-Based Ni-MLCC with Ultra-Thin Active Layers

“…In order to meet miniaturization requirement and increase the volumetric efficiency of MLCCs, the dielectric layer thickness has been reducing every year and it has reached under 1 µm [3]. The electric field applied to the dielectric layers increases with the reduction of the dielectric layer thickness [4][5]. Thus a serious problem has been coming out in the dielectric properties of MLCCs with ultra-thin dielectric layers, which is the insulation resistance degradation under DC electric fields.…”