Electronic device, dielectric ceramic composition and the production method

Abstract

A dielectric ceramic composition comprising a main component including BaTiO3, a fourth subcomponent including an oxide of R1 (note that R1 is at least one selected from Y, Ho, Er, Tm, Yb and Lu) and a fifth subcomponent including an oxide of R2 (note that R2 is at least one selected from Dy, Tb, Gd and Eu); wherein a total number of moles of R1 and R2 with respect to 100 moles of the main component is 2 to 6 moles when calculated as a conversion of the R1 and a conversion of the R2, and a ratio of the fifth subcomponent to the total number of moles of R1 and R2 with respect to 100 moles of the main component is in a relationship of 0.5≦R2/(R1+R2)≦0.75 when calculated as a conversion of the R1 and a conversion of the R2. According to the present invention, a high temperature load lifetime and capacity-temperature characteristics can be well balanced even when the dielectric layer of the electronic device is made thin, so that a sufficiently reliable dielectric ceramic composition can be provided.

Description

BRIEF DESCRIPTION OF DRAWINGS

These and other objects and features of the present invention will become clearer from the following description of the preferred embodiments given with reference to the attached drawing, in which:

FIG. 1 is a sectional view of a multilayer ceramic capacitor according to an embodiment of the present invention.

Claims

1. A dielectric ceramic composition comprising: a main component including barium titanate;a first subcomponent including MgO;a second subcomponent including a SiO2 based sintering aid;a third subcomponent including at least one selected from V2O5, MoO3 and WO3;a fourth subcomponent including an oxide of R1 (note that R1 is at least one selected from Y, Ho, Er, Tm, Yb and Lu);a fifth subcomponent including an oxide of R2 (note that R2 is at least one selected from Dy, Tb, Gd and Eu); anda sixth subcomponent including at least one of MnO and Cr2O3:whereinratios of respective subcomponents with respect to 100 moles of said main component arethe first subcomponent: 0.8 to 2 moles,the second subcomponent: 1.5 to 5 moles,the third subcomponent: 0.01 to 0.1 mole,the fourth subcomponent: 0.5 to 2 moles (note that the number of moles of the fourth subcomponent is a ratio of R1 alone),the fifth subcomponent: 1.5 to 4.5 moles (note that the number of moles of the fifth subcomponent is a ratio of R2 alone), andthe sixth subcomponent: 0.1 to 0.2 mole;a total number of moles of the fourth subcomponent and the fifth subcomponent with respect to 100 moles of said main component is 2 to 6 moles when calculated as a conversion of said R1 and a conversion of said R2; anda ratio of the fifth subcomponent to the total number of moles of the fourth subcomponent and the fifth subcomponent with respect to 100 moles of the main component is in a relationship of 0.5≦R2/(R1+R2)≦0.75 when calculated as a conversion of said R1 and a conversion of said R2.

2. An electronic device including a dielectric layer composed of the dielectric ceramic composition as set forth in claim 1, wherein a thickness of one of said dielectric layers is 4 μm or thicker and 7 μm or thinner.

3. The electronic device as set forth in claim 2, being used under a condition where electric field strength of 14 V/μm is imposed per one dielectric layer by applying a direct-current voltage.

4. A production method of the dielectric ceramic composition as set forth in claim 1, comprising the steps of: obtaining a dielectric ceramic composition powder by mixing a material of said main component and materials of said first to sixth subcomponents; andobtaining a dielectric ceramic composition by firing said dielectric ceramic composition powder:whereina material having an average particle diameter of 0.1 to 0.3 μm is used as the material of said main component; andfiring is performed, so that an average particle diameter of dielectric particles included in said dielectric ceramic composition after firing becomes 1.5 times to 2.0 times as large as an average particle diameter of the material of said main component.