Article ID: 23-00059
Synchrotron X-ray nano computed tomography was employed to study how the microstructure changes during the co-sintering process of multi-layer ceramic capacitors (MLCC). MLCCs are composed of alternating Ni electrodes and BaTiO3 dielectric layers. When the thickness of the electrodes was reduced to submicron levels, on the order of a few particle diameters, it led to the development of defects in the inner electrodes, resulting in a loss of capacitance. The discontinuous electrode region contained circular holes and irregularly shaped channels. The creation of these gaps was linked to an increase in the characteristic length of the non-uniform electrode structure, which can be described as a coarsening process. The transformation of the electrode's shape through surface/interface diffusion triggered the separation of the material connecting two holes. This separation was driven by instability induced by surface tension and stress, causing the material to form sharp points as it broke apart. These sharp points could potentially enhance the local electric field and lead to dielectric breakdown. An explanation was provided for the generation of defects arising from the arrangement of heterogeneous particles in the electrode layer.
