JPH0815008B2 - Dielectric porcelain composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Field of Industrial Application> This invention has a high dielectric constant of 5000 or more and a sintering temperature of 900.
The present invention relates to a dielectric ceramic composition having a low temperature of up to 1000 ° C. and a small rate of change in capacitance with temperature.

<Conventional Technology and Its Problems> Conventionally, a material mainly composed of BaTiO ₃ is known as a high dielectric constant type ceramic capacitor material.

However, the rate of change in capacitance with temperature is JI.
B characteristics of S standard (ΔC / C ₂₀ = ± 10 at -25 ° C to + 85 ° C)
%), The permittivity in greenhouse is as low as 2000.

Furthermore, these composition systems have sintering temperatures of 1300
It has a high defect of ~ 1400 ℃.

For this reason, the firing cost is high, and in a laminated porcelain capacitor, multiple pre-formed electrodes are stacked on a raw porcelain sheet and then fired. In this case, it has been necessary to use a noble metal having a high melting point, such as platinum or palladium, which does not melt, oxidize, or react with the dielectric.

On the other hand, in the lead composite perovskite dielectric ceramic composition, a composition system having a relative dielectric constant of 10,000 or more and a sintering temperature of 1100 ° C. or less is already known.

However, these have a large rate of change in capacitance with temperature. Therefore, the rate of change of capacitance with temperature is small,
A dielectric ceramic composition having a high dielectric constant and capable of firing at 1000 ° C. or lower has been desired in order to perform stable firing by reducing lead volatilization during firing.

<Means for Solving Problems> The present invention adds one or more of MgO and ZnO to a ternary solid solution of Pb (Mg _1/2 W _1/2 ) O ₃ -PbTiO ₃ -PbZrO _3. By doing so, it was possible to reduce the rate of change in capacitance with temperature and increase the dielectric constant.

In other words, the main component Pb (Mg _1/2 W _1/2 ) O ₃ -PbTiO ₃ -P
A ternary solid solution dielectric ceramic composition of bZrO ₃ has already been proposed (Japanese Patent Laid-Open No. 58-60671).
However, in the above proposal, the rate of change in capacitance with temperature is
JIS standard B characteristics (ΔC / Co = ± 1 at -25 ℃ to + 85 ℃)
Those satisfying 0) have a dielectric constant of 2500 or less.

Therefore, the inventors of the present invention have a dielectric constant of 5000 or more, a capacitance change rate with respect to temperature that satisfies the JIS standard B characteristic (ΔC / C ₂₀ = ± 10% at −25 ° C. to + 85 ° C.), and the firing temperature is 900
As a result of investigations to obtain a dielectric ceramic composition as low as 1000 ° C., the present invention has been achieved.

That is, the present invention is _{Pb (Mg 1/2 W 1/2) O} 3 -PbTiO 3 -PbZrO
_In a porcelain composition composed of a three-component solid solution of 3, the weight ratio (%) of individual oxide compositions constituting the porcelain composition
Is Pb ₃ O ₄ 66.96 to 67.60 MgO 2.60 to 3.10 WO ₃ 14.94 to 17.80 TiO ₂ 8.94 to 10.88 ZrO ₂ 1.40 to 5.78, and the Pb (Mg _1/2 W _1/2 ) O ₃ -PbTiO ₃ -PbZrO ₃
When the weight ratio when expressed as Pb (Mg _1/2 W _1/2 ) O ₃ 47.0 to 56.0 PbTiO ₃ 34.5 to 42.0 PbZrO ₃ 4.0 to 16.5 is 100 parts by weight when the main component is As a dielectric ceramic composition, the content of one or more of MgO and ZnO is 0.3 parts by weight or more and 2.0 parts by weight or less, or Mn is converted to MnO ₂ and 2.0 parts by weight or less. is there.

Here, the main component represented by Pb (Mg _1/2 W _1/2 ) O ₃ -PbTiO ₃ -PbZrO ₃ is represented by the following A (56.0, 40.0, 4.0) B (50.0 , 34.5, 15.5) C (47.0, 36.5, 16.5) D (53.0, 42.0, 5.0) on the line connecting the composition points (% by weight) and the composition range surrounded by these four points.

<Operation> In the present invention, the reason for limiting the ranges of the main component and the sub-components as described above will be described below.

First, the reason for limiting the composition of the main component will be explained. Outside the line connecting the composition points A and B shown in the figure, the dielectric constant is lower than 5000, and the capacitance change rate with temperature is B of JIS standard.
It is not preferable because the characteristics (ΔC / C ₂₀ = ± 10% at -25 ° C to + 85 ° C) are not satisfied.

Outside the line connecting the composition points B, C and C, D, the rate of change in capacitance with respect to temperature does not satisfy the B characteristic of the JIS standard described above, which is not preferable.

Further, outside the line connecting the composition points D and A, the dielectric loss becomes larger than 1%, and the rate of change in capacitance with temperature does not satisfy the B characteristic of JIS standard, which is not preferable.

Next, the reason for limiting the composition range of the subcomponents will be described.
One or more of O or ZnO added to the main component
When the amount is less than 0.3 parts by weight, the dielectric loss becomes larger than 1% and the rate of change in capacitance with temperature does not satisfy the B characteristic of JIS standard, which is not preferable.

In addition, the addition amount of one or more of MgO and ZnO is 2.0
When it is more than parts by weight, the dielectric constant is less than 5000, which is not preferable.

Furthermore, when the amount of MnO ₂ added is more than 2.0 parts by weight with respect to the main component, the dielectric loss is greater than 1%, and the rate of change in capacitance with temperature does not satisfy the B characteristics of JIS standards. Absent.

<Examples> The present invention will be described below with reference to Examples.

Industrial Pb ₃ O ₄ , MgO, WO ₃ , TiO ₂ , ZrO as starting materials
₂ , MnO ₂ is used and weighed in advance to Pb (Mg _1/2 W _1/2 )
O ₃ , PbTiO ₃ and PbZrO ₃ were mixed respectively, wet-mixed in a ball mill and then evaporated to dryness.

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

Next, the compound powder thus obtained was blended so as to have each desired blending ratio shown in Table 1, 5 parts by weight of a vinyl acetate-based binder as a binder was added, and wet blended by a ball mill.

Then, it was evaporated to dryness and sized to give a powder, and this powder raw material was shaped into a disk with a diameter of 10 mm and a thickness of 1.2 mm at a pressure of 2.5 ton / cm ² .

Then, using an electric furnace having a Pb atmosphere, this disk is
Baking was performed for 2 hours at each temperature described in the column of "Baking temperature" in Table 2.

After that, an Ag paste was baked as an electrode at 800 ° C. to obtain a measurement sample.

The dielectric constant (ε) and the dielectric loss (tan δ) of each of the obtained samples were measured under the conditions of 1 KHz, 1 Vrms, and 20 ° C.
The rate of change in capacitance with respect to temperature was measured at -25 ° C and + 85 ° C with reference to the capacitance value at 20 ° C. The result is the second
Shown in the table.

It should be noted that the sample numbers marked with * are outside the scope of the claims of the present invention.

<Effects of the Invention> From the above table, the dielectric ceramic composition of the present invention has a dielectric constant of 50.
00 or more, dielectric loss 1% or less, firing temperature 900-1000
C., and the rate of change in capacitance with respect to temperature satisfied the JIS standard B characteristics (ΔC / C ₀ = ± 10% at −25 ° C. to + 85 ° C.).

In the sample preparation method, the starting materials were weighed from the beginning to a desired mixing ratio, wet mixed by a ball mill, evaporated and dried, and calcined at 750 ° C for 2 hours (Sample No. Also in 21), the same characteristics as in the case of the above-mentioned sample preparation method, that is, the method of preparing and mixing the compound powder of each composition in advance, were obtained.

[Brief description of drawings]

The drawings are explanatory views showing the composition ranges of the three components in the porcelain composition of the present invention.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display location H01G 4/12 C04B 35/46 H

Claims (2)

[Claims] [Claim 1] Pb (Mg _1/2 W _1/2) 3 of O ₃ -PbTiO ₃ -PbZrO ₃
In a porcelain composition comprising a solid solution of component system, the individual oxide composition weight ratio (%) constituting the porcelain composition is Pb ₃ O ₄ 66.96 to 67.60 MgO 2.60 to 3.10 WO ₃ 14.94 to 17.80 TiO ₂ 8.94 to 10.88 ZrO ₂ 1.40 to 5.78 and the Pb (Mg _1/2 W _1/2 ) O ₃ -PbTiO ₃ -PbZrO ₃
When the weight ratio when expressed as Pb (Mg _1/2 W _1/2 ) O ₃ 47.0 to 56.0 PbTiO ₃ 34.5 to 42.0 PbZrO ₃ 4.0 to 16.5 is 100 parts by weight when the main component is As a dielectric ceramic composition, the content of one or more of MgO and ZnO is 0.3 to 2.0 parts by weight. 2. A _{Pb (Mg 1/2 W 1/2) O} 3 3 of -PbTiO ₃ -PbZrO ₃
Contain at least 2.0 parts by weight of at least 0.3 parts by weight and at least 2.0 parts by weight of Mn converted to MnO ₂ , as an auxiliary component, relative to 100 parts by weight of the main component consisting of the component system. The dielectric porcelain composition according to claim 1, wherein: