Characterizing electrical breakdowns upon reoxidation atmosphere for reliable multilayer ceramic capacitors

• Published in: Hanʼguk Seramik Hakhoe chi 2021, 58(4), 395, pp.445-451
• Main Authors: Lee, Daehee, Song, Kwanwoo, Jung, Dongjun, Cha, Bermha, Park, Myungjun, Kim, Jonghan, Lee, Jong Ho
• Format: Article
• Language: English
• Subjects: Ceramics; Chemistry and Materials Science; Composites; Glass; Materials Science; Natural Materials; Original Article; 재료공학
• ISSN: 1229-7801; 2234-0491; 2334-0491
• DOI: 10.1007/s43207-021-00121-9

Electrical breakdowns of multilayer ceramic capacitors (MLCCs) manifest an increase in leakage current and are characterized as a function of atmospheric reoxidation. The atmospheric reoxidation is controlled with respect to the theoretical oxygen partial pressure for the oxidation of Ni internal electrodes. The breakdowns are characterized by a Maxwell–Wagner polarization technique, which dominantly exhibits space-charge-limited and Poole–Frenkel currents for all measured samples. The threshold voltage for the transition between these two conduction modes is suggested as an index for the robustness of the grain boundary resistance of BaTiO 3 ; therefore, the breakdown voltage. The reoxidation atmosphere, which prevents the Ni oxidation, increases the threshold voltage, dramatically enhancing the breakdown voltage and insulation resistance. Impedance spectroscopy and scanning transmission electron microscopy–energy-dispersive X-ray spectroscopy reveal that the cation distribution throughout BaTiO 3 grains and grain boundaries changes during the reoxidation, including Ni cations from the internal electrodes, which affects the grain boundary resistance and determines the breakdown voltage of MLCCs with Ni internal electrodes. These observations emphasize that the reoxidation should be concurrently optimized in terms of the cation redistribution and elimination of oxygen vacancies.