JPH0687364B2 - High dielectric constant porcelain composition - Google Patents

Description

TECHNICAL FIELD The present invention relates to a high dielectric constant porcelain composition for a grain boundary type semiconductor porcelain capacitor.

[Conventional technology]

Conventionally, barium titanate-based porcelain compositions are known to have a high dielectric constant and a small dielectric loss,
When the composition is used as a grain boundary type semiconductor ceramic capacitor, if the dielectric constant is high, the dielectric loss is large,
There are problems such as poor temperature characteristics and low insulation resistance, and low dielectric constants such as low dielectric constant.

[Object and Summary of Invention]

When used as a grain boundary type semiconductor ceramic capacitor, the object of the present invention is to obtain a high dielectric constant having a high dielectric constant and a small dielectric loss, particularly good temperature characteristics, high insulation resistance, and well-balanced electrical characteristics. An object is to provide a porcelain composition.

The above object of the present invention is 83.5 to 87 mol% barium titanate, 12 to 14 mol% barium stannate, and 0.05 to 0.17 mol% of a semiconducting agent with respect to a main component composition consisting of 1 to 2.5 mol% strontium titanate. And a small amount of a mineralizer, and firing is performed in a neutral or reducing atmosphere.

[Specific Description and Examples of Invention]

The main component composition referred to in the present invention refers to a combination of barium titanate, barium stannate and strontium titanate, and these components may be used as they are in the production of the composition, or Ti It is also possible to appropriately select and use oxides of Ba, Sn, Sr, carbonates and oxalates that become oxides when heated.

Further, as the semiconducting agent referred to in the present invention, La, Ce, Pr, Nd, S
Rare earth elements such as m, Gd, Dy and Ho can be mentioned, and these may be oxides or those which become oxides upon heating.

Further, any known mineralizing agent may be used in the present invention, but in general, SiO ₂ , Al ₂ O ₃ , ZnO and the like can be mentioned.

Each of the above-mentioned components is used so as to have substantially the above composition, and the object of the invention can be achieved within the range, but outside the range, the balance of the characteristics of the present invention such as temperature characteristics, dielectric loss, dielectric constant, and insulation resistance. Is damaged.

That is, when barium titanate exceeds 87 mol%, the temperature characteristics are impaired, and when it is below 83.5 mol%, the dielectric constant decreases. If the amount of barium stannate exceeds 14 mol%, the dielectric constant decreases, and if it falls below 12 mol%, the temperature characteristics deteriorate. When the amount of strontium titanate exceeds 2.5 mol% and becomes large, the temperature characteristics and the dielectric constant are impaired, and when it becomes less than 1.0 mol%, the dielectric loss becomes large.

Further, if the semiconducting agent also exceeds 0.17 mol%, the temperature characteristics will be impaired, and if it is less than 0.05 mol%, the dielectric constant and insulation resistance will deteriorate. Mineralizers may be small, for example 1 mol%.

The method for producing the high dielectric constant porcelain composition of the present invention is not particularly limited, and the following production method is generally practical.

That is, the main component, the semiconducting agent and the mineralizing agent are weighed with oxides, carbonates, etc. of the respective components so as to have a predetermined composition, and wet mixed with a ball mill or the like, and then 900 to 1400 ° C., preferably 1000 to Calcination at 1300 ℃. Further, a binder such as polyvinyl alcohol is added to this calcined product, and after pressure molding, it is baked at 1300 to 1500 ° C, preferably 1400 to 1450 ° C under a neutral or reducing atmosphere to obtain a high dielectric constant porcelain composition. be able to.

In the present invention, the use of the composition is limited to the grain boundary type semiconductor ceramic capacitor, but as a manufacturing method thereof, a known method can be adopted.

That, CuO to the above compositions, and applying an insulating agent such as Bi ₂ O _3, MnO _2, after heat treatment at 1200 to 1500 ° C. in air, Yotsute to baking electrode using a silver paste A grain boundary type semiconductor ceramic capacitor can be obtained.

〔Example〕

The raw materials of BaCO ₃ , TiO ₂ , SnO ₂ ,
SrCO ₃ , a semiconducting agent and a mineralizing agent were weighed in predetermined amounts and wet-mixed with a ball mill. After that, dry, crush,
It was calcined at 1000 to 1300 ° C in an air atmosphere. After crushing this calcined product, add an organic binder such as polyvinyl alcohol to mix and homogenize, dry and crush it to about 1000 kg.
It was pressure-molded into a disc or a square plate at a pressure of / cm ² . The thus pressure-molded product was fired at 1400 to 1450 ° C. in a nitrogen atmosphere or a mixed atmosphere of nitrogen and hydrogen. Then, at least one of CuO, Bi ₂ O ₃ , MnO _{2 and the} like was applied to this fired product, and diffusion treatment was performed at 1200 to 1500 ° C. in an air atmosphere. An electrode was formed by applying a silver paste on this surface and baking it at 800 ° C.

Table 2 shows the results of the electrical characteristics. In the table, the dielectric constant (ε
r), dielectric loss (tan δ) frequency is 1kH when the temperature is 25 ℃.
It is the value measured by z. The rate of change in capacity (TC) was evaluated by the change in the values at -25 ° C and 85 ° C with 25 ° C as the standard. The insulation resistance (IR) is a value when the applied voltage is a DC voltage of 50V.

[Effect of the invention] The porcelain composition of the present invention shows a high dielectric constant of 52000 or more,
1 to 1.9% when used as a grain boundary type semiconductor ceramic capacitor
And low dielectric loss, high insulation resistance of 17000 ~ 62400MΩcm, and especially good temperature characteristic of -3 ~ -20%, so it has well-balanced characteristics for grain boundary semiconductor porcelain capacitors such as audio equipment and communication equipment. Can be demonstrated.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Mitsunori Takasugi, Mitsunori Takasugi, Ube City, Ube City, Yamaguchi Prefecture, 5 1978, Ube Research Institute, Ube Laboratory (72) Inventor Masanori Kikuzawa, 3-9-15 Tajiri, Ichikawa City, Chiba Prefecture (56) Reference JP-A-57-167617 (JP, A)

Claims (1)

[Claims] 1. A semiconducting agent 0.05 to 0.17 mol% relative to a main component composition consisting of a combination of barium titanate 83.5 to 87 mol%, barium stannate 12 to 14 mol%, and strontium titanate 1 to 2.5 mol%. And a small amount of mineralizer,
A high dielectric constant porcelain composition for a grain boundary type semiconductor porcelain capacitor, which is characterized by being fired in a neutral or reducing atmosphere.