Dielectric ceramic and laminated ceramic capacitor

Abstract

To provide a dielectric ceramic, which has high permittivity and low dielectric loss, can satisfy X7R properties in EIA standards in a temperature change of specific permittivity, and can realize high insulating resistance even in the case of low applied voltage, and a laminated ceramic capacitor which comprises the dielectric ceramic as a dielectric layer and has an excellent service life property in a high-temperature load test. A dielectric ceramic composed mainly of barium titanate and containing predetermined amounts of vanadium, magnesium, manganese, and a rare earth element, wherein the diffracted intensity of a (004) face, which exhibits tetragonal barium titanate, is larger than the diffracted intensity of a (004) face, which exhibits cubic barium titanate, the crystal grain comprises a crystal grain having a calcium concentration of not more than 0.2 atomic% and a crystal grain having a calcium concentration of not less than 0.4 atomic%, the area ratio of the crystal grain having a calcium concentration of not less than 0.4 atomic% is 0.4 to 0.7, and the average diameter of the crystal grains is 0.21 to 0.28 [mu]m.

Description

technical field [0001] The present invention relates to a dielectric ceramic formed from crystal grains mainly composed of barium titanate, and a laminated ceramic capacitor using it 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, dielectric ceramics are required to have very high reliability in downsizing and increasing the capacity of capacitors for medium withstand voltages used at high rated voltages. [0003] Conventionally, base metals can be used as the m...

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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 permittivity satisfies the X7R characteristic of the EIA standard (-55 to 125° C., the change rate of the relative permittivity is ±15 %), but there is a problem of large dielectric loss. In addition, although 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 drop 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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