Electrical Characteristics of Multilayered Ceramic Capacitors Depending on BaTiO 3 Particle Size
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ORIGINAL ARTICLE
Electrical Characteristics of Multilayered Ceramic Capacitors Depending on BaTiO3 Particle Size Jung‑Rag Yoon1 · Min Kee Kim1 Received: 17 December 2019 / Revised: 26 May 2020 / Accepted: 3 August 2020 © The Korean Institute of Electrical Engineers 2020
Abstract Multilayer ceramic capacitors were prepared with BaTiO3-based ceramics of different grain sizes (150–500 nm), having appropriate dielectric properties and high-temperature stability. The grain size effect on the dielectric properties and insulation resistivity of fine-grained B aTiO3 ceramics at room temperature and high temperatures under electric fields were investigated. The reduction in particle size has a strong effect on DC-bias characteristics and withstanding voltage characteristics per unit thickness. BaTiO3 ceramic capacitor with smaller grains had higher reliability under the DC bias and higher withstanding voltage per unit thickness due to the shell with para-electricity. The highly accelerated lifetime test showed that the insulation resistance with smaller particle size exhibited one order higher as the voltage increases at higher temperatures and the samples with a size of 500 nm had a sharp drop in insulation resistance at 200 V. Small particles (150, 250 nm) have a smaller product of insulation resistance and capacity than larger particles (500 nm). But, the withstanding voltage per unit thickness of the small particles (150, 250 nm) was 82, 71 V/μm, respectively, which was greater than 58 V/μm of the larger particles (500 nm). This is thought to be an effect of suppressing the movement of defects in the smaller particles because small grains have many grain boundaries. Keywords DC bias · Withstanding voltage · Shell · RC characteristics · Insulation resistance · Grain size
1 Introduction Multi-layered ceramic capacitors (MLCCs) are becoming more widely used in home appliances and aerospace applications. In particular, the demand for MLCCs required for power conversion in electric vehicles and autonomous driving is increasing rapidly. In order for MLCCs to be applied to electronic circuits in electric vehicles, MLCCs are required to have long life, electrical high voltage and high reliability compared to general products. Multilayered ceramic capacitors for electric vehicles should have reliability as the most important items, are classified according to their application into: products requiring high capacity and small size; and products requiring high voltage and low capacity. In order to develop highly reliable Ni-MLCCs, not only stabilization of the fabrication process but also development of a dielectric composition are required. The Ni-MLCC dielectric
* Jung‑Rag Yoon [email protected] 1
R&D Center, Samwha Capacitor, Yongin, Korea
composition has a core–shell structure, and depending on the size of BaTiO3 particles and on additives, the thickness of the core and the shell may be controlled and the electrical properties may be improved [1]. MgO, which is a representative additive for forming the cor
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