Papers by Author: Koichiro Morita

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Authors: Koichiro Morita, Sadahiro Tsurekawa, H. Nakashima, H. Yoshinaga
Authors: Koichiro Morita, Yoshio Sakka, Keijiro Hiraga
Authors: Koichiro Morita, Keijiro Hiraga, Yoshio Sakka
Authors: Koichiro Morita, Youichi Mizuno, Hirokazu Chazono
Abstract: The lifetime determination model for multilayer ceramic capacitors (MLCCs) is discussed. The accumulation of oxygen vacancies on the cathode/ceramics interface by an electro-migration process is a concept accepted by many researchers. However, the lifetimes and leakage currents measured during a highly accelerated lifetime test (HALT) could not be explained by this concept. To investigate the mechanism, we used a polarity reversal method during the HALT, which provided information on the dominant process for the leakage current. Thermally stimulated current (TSC) measurement provided the relative number of oxygen vacancies both on the cathode/ceramics interfaces and the grain boundaries. Moreover, the microstructure of the MLCC samples was evaluated by both electric property measurements and direct observation. From these results, we concluded that the grain boundaries controlled the leakage current as well as the lifetime.
Authors: Koichiro Morita, Youichi Mizuno, Hirokazu Chazono, Hiroshi Kishi
Authors: Hisanori Yamane, Koichiro Morita, Masahiko Shimada
Authors: K. Tsugawa, A. Hokazono, Hiroshi Noda, K. Kitatani, Koichiro Morita, Hiroshi Kawarada
Authors: Byung Nam Kim, Koichiro Morita, Keijiro Hiraga, Yoshio Sakka
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