Dielectric ceramic and laminated ceramic capacitor

Abstract

This invention provides a dielectric ceramic comprising crystal grains having a core-shell structure composed mainly of barium titanate and a solid solution of calcium, vanadium, magnesium, manganese, and at least one rare earth element selected from, yttrium, dysprosium, holmium, erbium, and terbium, and a grain boundary phase present among the crystal grains. A dielectric ceramic having a high permittivity, a small change in specific permittivity depending upon the temperature, and, at the same time, no significant dependence of insulating resistance upon voltage can be produced by incorporating vanadium, magnesium, rare earth element, and manganese in a predetermined ratio into the crystal grains and bringing a Curie temperature to a range of 95 to 105 C.

Description

technical field [0001] The present invention relates to a dielectric ceramic composed of crystal grains mainly composed of barium titanate, and a laminated ceramic capacitor using this as a dielectric layer. Background technique [0002] In recent years, with the popularization of mobile devices such as mobile phones and the increase in speed and frequency of semiconductor elements that are the main components of computers and the like, the demand for smaller and higher capacitance of multilayer ceramic capacitors mounted in such electronic devices has gradually increased. , The dielectric layer constituting the multilayer ceramic capacitor is sought to be thinner and higher in lamination. [0003] In addition, as dielectric ceramics for the dielectric layer constituting the laminated ceramic capacitor, a dielectric material mainly composed of barium titanate (hereinafter referred to as barium calcium titanate) in which calcium is dissolved has been used conventionally. . ...

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Problems solved by technology

[0007] However, the improvement of the relative permittivity and the stability of the temperature characteristic of the relative permittivity of the dielectric ceramics including the crystal grains of the above-mentioned core-shell structure are excellent, but applying a DC voltage to the dielectric ceramics results in The problem that the decrease in insulation resistance (hereinafter referred to as the voltage dependence of insulation resistance) becomes larger when the DC voltage is increased

[0008] Also, as described above, a multilayer ceramic capacitor including a dielectric ceramic having crystal grains of a core-shell structure as a dielectric layer is difficult to obtain due to the voltage dependence of the insulation resistance in the dielectric ceramic as described above. Improving life characteristics in high temperature load tests

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