JPH0815009B2 - Dielectric porcelain composition - Google Patents

Description

TECHNICAL FIELD The present invention relates to a dielectric ceramic composition, and particularly to a dielectric ceramic composition suitable as a dielectric material such as a multilayer capacitor.

(Prior Art) Conventionally, BaTiO _{3 has been} used as a high dielectric constant porcelain capacitor material.
There is a dielectric ceramic composition mainly composed of

(Problems to be solved by the invention) In such a conventional dielectric ceramic composition, the rate of change of the capacitance value with respect to the temperature change is the B characteristic of JIS standard (+ 20 ° C).
Is satisfied characteristic) that the rate of change [Delta] C / C ₂₀ of the electrostatic capacitance value is within 10% ± at -25 ℃ ~ + 85 ℃ relative to the capacitance value C _20, is a dielectric constant at room temperature of 2,000 in And low.

Further, these conventional dielectric compositions have the drawback that the sintering temperature is as high as 1,300 to 1,400 ° C. Therefore, the firing cost is high. Moreover, when a laminated ceramic capacitor is manufactured using such a conventional dielectric ceramic composition, it does not melt or oxidize even at a high temperature of 1,300 ° C. or more and does not react with the dielectric material as a material for the internal electrodes. It was necessary to use expensive high melting point precious metals such as platinum and palladium.

Further, conventionally, a dielectric ceramic composition having a lead component and a composite perovskite structure, which has a sintering temperature of 1,100 ° C. or less and a relative dielectric constant of 10,000 or more, is known. However, these have a large rate of change in the capacitance value with respect to temperature changes.

For this reason, conventionally, dielectric ceramics that can be fired at 1,000 ° C or less to reduce the volatilization amount of lead during firing and can be fired at 1,000 ° C or less, and have a small rate of change in capacitance value with temperature change A composition was desired.

Therefore, the main object of the present invention is that the firing temperature is 90%.
It is intended to provide a dielectric ceramic composition having a low value of 0 to 1,000 ° C., a high dielectric constant of 5,000 or more, and a small rate of change in capacitance value with respect to temperature change.

The present invention (means for solving the problem) is the general formula _{XPb (Mg 1/2 W 1/2) O} 3 -YPbTiO 3 -Z
Mol% X, Y and Z represented by PbZrO ₃ (provided that X + Y
+ Z = 100) is the following points A, B, C and D (mol% X, mol% Y, mol% Z) A (52.0,44.0,4.0) B (47.0,38.0,15.0) C (42.0, 41.0,17.0) Pb of the composition within the range enclosed by the polygon with D (46.0,48.0,6.0) as the vertex
Of the main component obtained by substituting 0.5 to 10 mol% of at least one selected from Ba, Sr, and Ca for 100 parts by weight of the main component and one of MgO and ZnO as a subcomponent. Is a dielectric porcelain composition containing 0.3 to 4.0 parts by weight.

(Effect of the Invention) According to this invention, the firing temperature is as low as 900 to 1,000 ° C., the dielectric constant is as high as 5,000 or more, and the rate of change of the capacitance value with respect to temperature change is JIS standard B characteristic (static at + 20 ° C.). the rate of change [Delta] C / C ₂₀ of the electrostatic capacitance value satisfies certain characteristics) within 10% ± at -25 ℃ ~ + 85 ℃ relative to the capacitance value C _20, dielectric ceramic composition is obtained.

The above-mentioned objects, other objects, features and advantages of the present invention will become more apparent from the following detailed description of the embodiments with reference to the drawings.

(Example) First, as a starting material, industrial Pb ₃ O ₄ , MgO, WO ₃ , and TiO 2 were used.
₂ , ZrO ₂ , BaCO ₃ , SrCO ₃ , CaCO ₃ , ZnO and MnO ₂ were prepared. Then, if calcined, these raw materials are weighed so that the weight ratio of the main component and the sub-component becomes the weight ratio shown in the attached table 1, they are wet-mixed by a ball mill, and then evaporated and dried to obtain a powder mixture. Got

Next, the powder mixture was calcined at 750 ° C. for 2 hours to obtain a predetermined compound powder.

After adding 5 parts by weight of a vinyl acetate binder as a binder to the obtained compound powder, they were wet-mixed with a ball mill to obtain a mixture.

Then, they make a powder raw material was sized The mixture was evaporated to dryness, 10mm diameter of the powder raw material at a pressure of 2.5 ton / cm ^2,
A 1.2 mm thick disc was formed to obtain a molded product.

This disk-shaped molded product was fired in an electric furnace having a Pb atmosphere at the optimum firing temperature shown in Appendix 2 for 2 hours.

Then, Ag paste was baked on both surfaces of the fired product at 800 ° C. to form electrodes, and samples 1-33 were prepared.

Then, for each sample, the dielectric constant ε and the dielectric loss ta
nδ was measured under the conditions of 1kHz, 1Vrms, and 20 ℃. Further, for each sample, the rate of change ΔC / C ₂₀ of the capacitance value with respect to the temperature change from −25 ° C. to + 85 ° C. was measured with the capacitance value C ₂₀ at + 20 ° C. as a reference. Table 2 shows the measurement results. In Appendix 2, numerical values with poor characteristics are underlined. In this case, the firing temperature should be over 1,000 ° C, the dielectric constant should be less than 5,000, the dielectric loss should be more than 1%, and the change rate of the capacitance value with respect to temperature change should be ΔC / C ₂₀ . Shows values outside the range of ± 10% as poor numerical values.

In addition, Pb (Mg
A three-component composition diagram (triangle diagram) showing the composition ratio of the three component compositions of _1/2 W _1/2 ) O ₃ , PbTiO ₃ and PbZrO ₃ is shown. In this drawing, the circled numbers represent the sample numbers.
Further, in this drawing, the region representing the composition ratio of the composition to be the main component within the scope of the present invention is represented by a polygon having vertices A, B, C and D.

That is, compositions within the scope of this invention have the general formula XP
b (Mg _1/2 W _1/2 ) O ₃ -YPbTiO ₃ -ZPbZrO ₃ mol%
X, Y and Z (where X + Y + Z = 100) are the following points
A, B, C and D (mol% X, mol% Y, mol% Z) A (52.0,44.0,4.0) B (47.0,38.0,15.0) C (42.0,41.0,17.0) D (46.0,48.0, Of the composition within the range surrounded by the polygon with 6.0) as the vertex
Of the main component obtained by substituting 0.5 to 10 mol% of at least one selected from Ba, Sr, and Ca for 100 parts by weight of the main component and one of MgO and ZnO as a subcomponent. the containing 0.3 to 4.0 parts by weight, further, Mn was contained 0 to 2.0 parts by weight in terms of MnO _2, a dielectric ceramic composition.

The reason why the dielectric ceramic composition according to the present invention is limited to the above range is as follows.

In other words, in the composition region outside the line segment connecting the composition points A and B shown in the drawing like sample number 2, the dielectric constant is 5,000.
It is lower and the rate of change of capacitance value with temperature change is JI.
It is not preferable because it does not satisfy the B characteristics of the S standard.

Further, in the composition region outside the line segment connecting the composition points B and C and the composition region outside the line segment connecting the composition points C and D, as in sample numbers 9 and 10, the capacitance with respect to the temperature change is obtained. It is not preferable because the rate of change of the value does not satisfy the JIS standard B characteristics.

In the composition region outside the line segment connecting the composition points D and A as in the sample number 3, the dielectric loss becomes larger than 1% and the rate of change of the capacitance value with respect to the temperature change is the B characteristic of JIS standard. It is not preferable because it is not satisfied.

Further, when part of Pb in the composition to be the main component is not replaced with Sr, Ca, or Ba as in Sample No. 12,
It is not preferable because the permittivity becomes smaller than 5,000 and the rate of change of capacitance value with respect to temperature change does not satisfy the B characteristic of JIS standard.

When a part of Pb in the main component is replaced with Sr, Ca or Ba in an amount of more than 10 mol% as in Sample Nos. 15, 18 and 21, the dielectric constant becomes less than 5,000 and the firing temperature increases.
The temperature is higher than 1,000 ℃, which is not preferable.

On the other hand, as in sample numbers 22, 23, and 27, the secondary component MgO
When the addition amount of one or more of ZnO and ZnO is less than 0.3 parts by weight with respect to the main component, the dielectric loss becomes larger than 1% and the rate of change of capacitance value with temperature change does not satisfy the JIS standard B characteristics. It is not preferable.

When the amount of one or more of MgO and ZnO added is more than 4.0 parts by weight as in Sample Nos. 26 and 30, the dielectric constant is less than 5,000, which is not preferable.

Further, when the amount of MnO ₂ added is more than 2.0 parts by weight with respect to the main component as in Sample No. 33, the dielectric loss becomes greater than 1% and the rate of change of the capacitance value with respect to temperature change is JIS standard B. It is not preferable because the characteristics are not satisfied.

On the other hand, in the samples within the scope of the present invention, the firing temperature was as low as 900 to 1,000 ° C., the dielectric constant was as high as 5,000 or more, the dielectric loss was as low as 1% or less, and the rate of change of the capacitance value with respect to temperature change was JIS. Satisfies the standard B characteristics.

[Brief description of drawings]

The drawing is a triangular diagram showing the range of the compounding ratio of the composition to be the main component of the present invention.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI technical display location H01G 4/12 4/30 7924-5E C04B 35/00 J

Claims (2)

[Claims] 1. A general formula XPb (Mg _1/2 W _1/2 ) O ₃ --YPbTiO ₃ --ZPb
Mol% X, Y and Z represented by ZrO ₃ (provided that X + Y +
Z = 100) is the following points A, B, C and D (mol% X, mol%
Y, mol% Z) A (52.0,44.0,4.0) B (47.0,38.0,15.0) C (42.0,41.0,17.0) D (46.0,48.0,6.0) Within the range surrounded by polygons Pb out of composition
Of the main component obtained by substituting 0.5 to 10 mol% of at least one selected from Ba, Sr, and Ca for 100 parts by weight of the main component, and MgO and ZnO as auxiliary components. A dielectric ceramic composition containing 0.3 to 4.0 parts by weight of one of them. 2. The dielectric ceramic composition according to claim 1, further comprising 2.0 parts by weight or less of Mn in terms of MnO ₂ with respect to 100 parts by weight of the main component.