JPH0817058B2 - Dielectric porcelain composition - Google Patents

Description

TECHNICAL FIELD The present invention relates to a dielectric ceramic composition, and particularly,
The present invention relates to a dielectric ceramic composition having a high value of 2500 or more, a small rate of change in capacitance with temperature, and a large specific resistance of 10 ¹⁰ Ωcm or more.

(Prior Art and Problems to be Solved by the Invention) Conventionally, there is a dielectric ceramic composition mainly composed of BaTiO ₃ as a high dielectric constant type ceramic capacitor material. However, in these porcelain compositions, the rate of change of capacitance with temperature is the JIS standard B characteristic (ΔC / C ₂₀ = -25 ° C to + 85 ° C).
Those satisfying ± 10%) have a low dielectric constant of 2000 at room temperature.

On the other hand, as a lead composite perovskite dielectric ceramic composition, a composition having a relative dielectric constant of 10,000 or more and a sintering temperature of 1050 ° C. or less is already known. However, these compositions have a rate of change in capacitance with temperature of -25 ° C to + 85 ° C.
It had a large defect of -50% to + 30% in the range of. Therefore, a composition having a small rate of change in capacitance with temperature and a high dielectric constant has been desired.

In manufacturing a multilayer capacitor using a dielectric ceramic composition containing lead oxide, internal electrodes are interposed between the dielectric material layers, but the dielectric material containing lead oxide is placed in a reducing atmosphere. In general, since the insulating properties are impaired when fired at 1, a stable noble metal such as a silver-palladium alloy that does not oxidize or dissolve even if fired in an oxidizing atmosphere and does not react with a dielectric is used as the internal electrode material. Commonly used. However, the material of the silver-palladium alloy is expensive and has the drawbacks that the characteristics are deteriorated by migration of silver and the equivalent series resistance is increased due to the small conductivity.

That is, in the multilayer capacitor, firstly, the dielectric porcelain has a high dielectric constant, secondly, the rate of change of the capacitance with respect to the temperature of the dielectric porcelain is small, and thirdly, there is no fear of migration and the conductivity is low. It is desired to use three internal electrodes having a high rate. Further, as an electrode that meets the above-mentioned third demand, there is an inexpensive copper or copper-based alloy material, but in order to use this, it must be a dielectric porcelain having a high specific resistance even if fired in a reducing atmosphere. I have to.

Therefore, the main object of the present invention is to provide a dielectric ceramic composition having a high dielectric constant, a small rate of change in capacitance with temperature, and a high specific resistance even when fired in a reducing atmosphere. It is to be.

(Means for Solving the Problems) The present invention is based on the fact that the compounding ratio (mol%) of the individual compounds constituting the composition of Pb (Mg _1/2 W _1/2 ) O ₃ -PbTiO ₃ is Pb (Mg _1/2 W _1/2 ) O ₃ : 55.0 to 70.0, PbTiO ₃ : 30.0 to 4
When the main component in the range of 5.0 is 100% by weight, the dielectric component containing ZnO in the range of 0.1% by weight or more and 2.0% by weight or less as a sub-component is added to the general formula aLi ₂ O + b (RO) + cB ₂ O. ₃ +
In the component represented by (1-a-b-c) SiO ₂ , a, b,
The values of c are 0 ≦ a <0.2, 0.1 ≦ b <0.55, 0, respectively.
A dielectric material containing 0.05 wt% or more and 6 wt% or less of a lead composite perovskite reduction inhibitor within the range of ≦ c <0.4 (where RO is at least one of BaO, CaO, SrO, and MgO). It is a porcelain composition.

(Effects of the Invention) According to the present invention, the rate of change of capacitance with respect to temperature is small and the dielectric constant is large, and further, for example, even if firing is performed in a reducing atmosphere in which the copper electrode does not oxidize, the resistivity and the dielectric loss are reduced. A dielectric porcelain composition having no deterioration in electrical characteristics can be obtained.

More specifically, regarding the Pb (Mg _1/2 W _1/2 ) O ₃ -PbTiO ₃ -based dielectric porcelain composition which is the main component of the composition according to the present invention, NNKraink and AIAgrarovskaya (Fiziko
Tverdogo Tela, Vo2, No1.pp70-72Jarnary, 1960), but the rate of change in capacity with temperature is as large as ± 50%, and the specific resistance is not mentioned.

On the other hand, in the present invention, Pb (Mg _1/2 W _1/2 ) O ₃ -P
By mixing a ZnO-added dielectric component in a two-component system made of bTiO ₃ with a lead composite perovskite reduction inhibitor,
High permittivity of 2500 or more, and change rate of capacitance with temperature are JIS standard B characteristics (at -25 ℃ to + 85 ℃, ΔC / C ₂₀
= ± 10%), the specific resistance is 10 ¹⁰ Ωcm or more, the firing temperature is as low as 900 to 1050 ° C., and the firing is possible in a low oxygen partial pressure atmosphere in which the copper electrode is not oxidized. Was obtained.

The above objects, other objects, features and advantages of the present invention will be more apparent from the detailed description of the embodiments below.

(Example) As a raw material of a dielectric material of a lead composite perovskite, Pb ₃ O ₄ ,
MgO, WO ₃ , TiO ₂ , ZnO, and MnO ₂ were weighed so as to have the compositions shown in Tables 1 and 2, wet-mixed in a ball mill for 16 hours, and then evaporated to dryness to obtain a mixed powder.

The obtained mixed powder is put in a zirconia-like box and 680 ℃
After firing for 2 hours, it was roughly pulverized so as to pass through a 200-mesh sieve to prepare a lead composite perovskite powder.

Further, oxides, carbonates or hydroxides of the respective components were blended so as to obtain the lead anti-reduction agent for lead composite perovskite having the compositions shown in Appendix 1 and Appendix 2, and these were wet mixed in a ball mill for 16 hours. After crushing, it was evaporated to dryness to obtain a powder. The resulting powder is placed in an alumina crucible, left at 1300 ° C for 1 hour, then rapidly cooled to vitrify, then coarsely crushed to pass through a 200-mesh sieve, and for lead-composite perovskite A reduction inhibitor was prepared.

Next, the prepared lead-composite perovskite powder with vitrification of the lead-composite perovskite reducing agent is shown in Appendix 1
Then, a polyvinyl butyral binder and an organic solvent were added thereto, and the mixture was wet-mixed in a ball mill for 16 hours. Then, this was molded into a sheet-shaped green sheet by the doctor blade method, dried, and then cut into an appropriate size.
Then, the cut green sheets were printed with a copper electrode paste by a screen printing method, and then they were pressure-bonded and laminated.

After the pressure-bonded green sheet was cut to a specified standard, copper paste was applied as an external electrode to both end surfaces of the green sheet to form a laminated unit.

The laminated unit thus formed was placed in an electric furnace adjusted to a reducing atmosphere in which a copper electrode did not oxidize using a mixed gas of H ₂ , H ₂ O and N ₂ , and the mixture was heated at 900 to 1050 ° C for 2 hours. Firing was performed to obtain a multilayer capacitor (sample).

The obtained multilayer capacitor (sample) was immersed in a drip solution and tested for the degree of sintering to determine the optimum firing temperature.

For each sample, 1KHz, 1Vr at 25 ℃
The dielectric constant (ε) in ms, the dielectric loss (tan δ), the specific resistance, and the temperature characteristics of the dielectric constant based on + 20 ° C in the temperature range of -25 to + 85 ° C were measured. The measurement results are shown in Tables 1 and 2.

In Tables 1 and 2, regarding the temperature characteristics, B,
Each characteristic of C, D and F means a temperature characteristic according to JIS standard, and each characteristic will be described in detail as follows.

B characteristic: -25 ℃ ~ based on capacitance at 20 ℃
The rate of change in capacity at + 85 ° C does not exceed -10 to + 10%.

C characteristics: -25 ℃ to +8 based on capacitance at 20 ℃
The rate of change in capacity at 5 ° C does not exceed -20 to + 20%.

D characteristic: -25 ℃ ~ based on capacitance at 20 ℃
The rate of change in capacity at + 85 ° C does not exceed -30 to + 20%.

F characteristic: -25 ° C ~ based on capacitance at 20 ° C
The rate of change in capacity at -85 ° C does not exceed -80 to + 30%.

In Tables 1 and 2, those marked with * are outside the scope of the present invention.

Next, the reason why the composition range of the composition according to the present invention is limited will be described.

First, the reason for limiting the composition range of the main component will be described.

Pb [(Mg _1/2 W _1/2 ) zTi _1- z] O ₃ (where 0 ≦ z ≦
If z is less than 0.55 or z
When is greater than 0.70, the dielectric constant becomes less than 2500 when mixed with a lead compound perovskite reduction inhibitor.
Moreover, the rate of change of capacitance with respect to temperature does not satisfy JIS standard B characteristics (ΔC / C ₂₀ = ± 10% from -25 ° C to + 85 ° C), which is not preferable (sample numbers 1 to 3 and 10 to 12).
reference).

Next, the reason for limiting the composition range of the subcomponents will be described.

When the added amount of ZnO is less than 0.1% by weight with respect to 100% by weight of the main component, the specific resistance becomes less than 10 ¹⁰ Ωcm,
Moreover, the rate of change of capacitance with respect to temperature does not satisfy the JIS standard B characteristics, which is not preferable (see sample number 13).

On the other hand, when the amount of ZnO added is more than 2.0% by weight, when the lead composite perovskite reduction inhibitor is mixed, the dielectric constant becomes less than 2500, and the rate of change in capacitance with temperature is JIS standard B It is not preferable because it does not satisfy the characteristics (see sample number 16).

Furthermore, the amount of MnO ₂ added is 1.5 based on 100% by weight of the main component.
If it exceeds 5% by weight, the dielectric loss exceeds 5%, the rate of change in capacitance with temperature does not satisfy the JIS standard B characteristics, and the specific resistance is less than 10 ¹⁰ Ωcm, which is not preferable. See number 19.).

Next, the reason for limiting the composition range of the lead-containing composite perovskite reduction inhibitor will be described.

That is, when b (RO) is less than 10 mol%, the lead-based composite perovskite dielectric cannot be fired at a low oxygen partial pressure (eg, 1000 ° C., about 10 ⁻⁷ atm or less) that can be used as a copper electrode (sample number). 36, 37, 38, 39).

If b (RO) is less than 10 mol%, the dielectric loss is 5%.
It is not preferable because it becomes larger and the specific resistance becomes smaller (see sample numbers 36, 37, 38, 39).

On the other hand, when b (RO) is 55 mol% or more, the firing temperature is 1050.
The temperature exceeds ℃ and the copper electrode melts and begins to flow, making it impossible to achieve the object of the present invention (see sample numbers 28, 29, 30, 31).

Further, a (Li ₂ O) is 20 mol% or more or c (B ₂ O ₃ )
When the content is 40 mol% or more, the dielectric properties are significantly impaired, or softening deformation occurs before firing is completed (see sample numbers 44 and 46).

Lastly, the reason why the addition amount of the lead composite perovskite reduction inhibitor is limited to 0.05% by weight or more and 6% by weight or less will be described. That is, when the amount added is less than 0.05% by weight, the dielectric is reduced and the specific resistance deteriorates (see sample numbers 22 and 23). On the other hand, the amount added is 6% by weight
When it exceeds, the dielectric constant becomes smaller than 2500, which is not preferable (see Sample No. 51).

It should be noted that firing at a partial pressure of oxygen higher than about 10 ⁻⁷ atm is not preferable because the copper electrode is oxidized (see Sample No. 21).

As is clear from the results shown in Appendix 1 and Appendix 2,
According to the present invention, the dielectric constant is as high as 2500 or more, the B characteristic of JIS standard is satisfied, the specific resistance is 10 ¹⁰ Ωcm or more, the optimum sintering temperature is as low as 900 to 1050 ° C., and the copper electrode is not oxidized. It can be seen that a dielectric ceramic composition that can be fired in a low oxygen partial pressure atmosphere is obtained.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Internal reference number FI Technical display location H01G 4/12 358 (72) Inventor Yukio Sakabe 2 26-10 Tenjin, Nagaokakyo-shi, Kyoto Stock company Murata Manufacturing Co., Ltd. (56) Reference JP 62-287510 (JP, A) JP 55-158685 (JP, A)

Claims (2)

[Claims] 1. A compounding ratio (mol%) of individual compounds constituting a composition of Pb (Mg _1/2 W _1/2 ) O ₃ -PbTiO ₃ is Pb (Mg _1/2 W _{1 / 2} ) Dielectric component containing ZnO in the range of 0.1 wt% or more and 2.0 wt% or less as an accessory component when the main component in the range of O ₃ : 55.0 to 70.0 PbTiO ₃ : 30.0 to 45.0 is 100 wt%. And the general formula aLi ₂ O + b (RO) + cB ₂ O ₃ + (1-a-b-c) Si
In the component represented by O ₂ , the values of a, b, and c are 0 ≦ a <0.2 0.1 ≦ b <0.55 0 ≦ c <0.4 (where RO is BaO, CaO, SrO, and MgO). One or more) of lead compound perovskites within the range of 0.
A dielectric porcelain composition containing from 05% by weight to 6% by weight. 2. Further, with respect to 100% by weight of the main component, M
The dielectric ceramic composition according to claim 1, which contains 1.5% by weight or less of n converted to MnO ₂ .