Dielectric ceramic and laminated ceramic capacitor

Abstract

To provide a dielectric ceramic, which has high permittivity, has specific permittivity which varies depending upon temperature so as to satisfy X5R characteristics in EIA specifications, and can realize high insulation resistance even in the case of low applied voltage, and a laminated ceramic capacitor which comprises the dielectric ceramic as a dielectric layer and is excellent in service life properties in a high-temperature load test. A dielectric ceramic composed mainly of barium titanate having a different Ca concentration. The dielectric ceramic contains, based on 100 moles of barium constituting the dielectric ceramic, 0.05 to 0.3 mole, in terms of V2O5, of vanadium, 0 to 1 mole, in terms of MgO, of magnesium, 0 to 0.5 mole, in terms of MnO, of manganese, and 0.4 to 1.5 moles, in terms of RE2O3, of a rare earth element (RE) selected from yttrium, dysprosium, holmium, and erbium. In an X-ray diffraction chart of the dielectric ceramic, the diffraction intensity of (004) plane, which shows tetragonal barium titanate, is larger than the diffraction intensity of (400) plane which shows cubic barium titanate.

Description

technical field [0001] The present invention relates to a dielectric ceramic composed of crystal grains mainly composed of barium titanate, and a multilayer ceramic capacitor using this as a dielectric layer. Background technique [0002] In recent years, along with the increase in the density of electronic circuits, the demand for miniaturization of electronic components has increased, and the miniaturization and increase in capacity of multilayer ceramic capacitors have been rapidly advancing. Along with this, the thinning of the dielectric layer per layer of multilayer ceramic capacitors is progressing, and there is a demand for dielectric ceramics that can maintain reliability as a capacitor even when the thickness is thinned. In particular, in reducing the size and increasing the capacity of capacitors for medium withstand voltages used at high rated voltages, very high reliability is required for dielectric ceramics. [0003] Conventionally, base metals can be used as...

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Problems solved by technology

[0011] However, although the dielectric ceramics disclosed in the above-mentioned Patent Documents 1 to 3 have a high dielectric constant, the temperature change of the relative dielectric constant satisfies the X5R characteristic of the EIA standard, and a high insulation resistance can be obtained when the applied voltage is low. When the applied voltage is increased, there is a problem that the decrease in insulation resistance becomes larger

[0012] In addition, in a multilayer ceramic capacitor including these dielectric ceramics as a dielectric layer, it is difficult to satisfy the life characteristics in a high-temperature load test when the dielectric layer is thinned due to a decrease in the insulation resistance of the dielectric ceramics.

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