JPH0687365B2 - 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]

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

The above object of the present invention is barium titanate 83 to 94 mol%,
It contains 5 to 11 mol% of barium stannate and 1 to 6 mol% of strontium titanate, and contains 0.05 to 0.2 mol% of a semiconducting agent and 0.5 to 4 mol% of a mineralizing agent, and is calcined. It is achieved by a high dielectric constant porcelain composition characterized by being performed in a neutral or reducing atmosphere.

[Specific Description and Examples of Invention]

The main component composition used in the present invention is barium titanate,
Refers to the combination of barium stannate and strontium titanate, which may be used as they are in the production of the composition, or as an oxide of Ti, Ba, Sn, Sr or an oxide during heating. Carbonate, oxalate,
It can also be used selectively.

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 insulation resistance, etc. Be damaged.

That is, when barium titanate exceeds 94 mol%, the dielectric loss increases, and when it is less than 83 mol%, the dielectric constant decreases. When the amount of barium stannate exceeds 11 mol%, the dielectric constant decreases, and when it falls below 5 mol%, the dielectric loss increases. When the amount of strontium titanate exceeds 6 mol% and becomes large, the insulation resistance decreases, and when it becomes less than 1.0 mol%, the temperature characteristics are impaired. If the semiconducting agent also exceeds 0.2 mol%, the dielectric constant will decrease, and if it falls below 0.05 mol%, the insulation resistance will decrease. The dielectric constant of the mineralizer decreases when it is less than 0.5 mol% or more than 4 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 is, CuO, Bi ₂ O ₃ , an insulating agent such as MnO ₂ is applied to the above composition, and after heat treatment at 1200 to 1500 ° C. in air, the electrode is baked using a silver paste or the like to obtain particles. A field-type semiconductor ceramic capacitor can be obtained.

〔Example〕

The raw materials of BaCO ₃ , TiO ₂ , SnO ₂ ,
SrCO ₃ , semiconducting agent La ₂ O ₃ and mineralizing agent SiO ₂ were weighed in predetermined amounts and wet-mixed with a ball mill. Then dry,
It was crushed and calcined at 1000 to 1300 ° C in an air atmosphere. After the calcination product was crushed, an organic binder such as polyvinyl alcohol was added and mixed to homogenize, dried and crushed, and pressure-molded into a disc or a square plate at a pressure of about 1000 kg / 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 1 of CuO, Bi ₂ O ₃ , MnO ₂ etc.
The seeds were applied and subjected to a diffusion treatment at 1200-1500 ° 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 electrical characteristics and temperature characteristics. In the table, the dielectric constant (ε _r ) and the dielectric loss (tan δ) are values measured at a frequency of 1 kHz and a temperature of 25 ° C. Capacity temperature change rate (T.
C) 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 56000 or more,
1.4 to 3.8% when used as a grain boundary type semiconductor ceramic capacitor
Since it has a small dielectric loss, high insulation resistance of 6200 to 55600 MΩcm, and good temperature characteristics, it can exhibit balanced characteristics for grain boundary type semiconductor ceramic capacitors such as audio equipment and communication equipment. it can.

 ─────────────────────────────────────────────────── ─── 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. Barium titanate 83 to 94 mol%, barium stannate 5 to 11 mol%, and strontium titanate 1
~ 0.5 mol% to the main component composition consisting of a combination of ~ 6 mol% and 0.5 to 4 mol% of a mineralizing agent, and calcined in a neutral or reducing atmosphere A high dielectric constant porcelain composition for a grain boundary type semiconductor porcelain capacitor characterized by the above.