Characteristics and effects of interfacial interdiffusion in composite multilayer ceramic capacitors

Back-scattering (BS), second-electron image and energy dispersive X-ray (EDX) were used to investigate the reciprocal diffusion at the heterogeneous interfaces in composite multilayer ceramic capacitors (CMLCCs). It was found that a phenomenon of an evident interdiffusion existed at the interface of CMLCCs. The characteristics and effects of interdiffusion for different elements were studied in detail. The results obtained showed that silver diffusion was a typically physical migration, which can be mainly controlled by the sintering characteristics of the ceramics. Before the open pores on the surface of the ceramics disappear, the silver can diffuse mainly through the vapor phase, based on an evaporization–condensation mass transport principle. In addition, the diffusion between different ceramic dielectrics, such as Mg, Zn, and Ni, can be affected by the sintering temperature and time, and particularly by compositional gradients. In this paper, the effects of interdiffusion on dielectric properties and reliability of CMLCCs were also discussed.