JP3250927B2 - Dielectric porcelain composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is based on BaTiO ₃ as a main component and comprises Nb ₂ O ₅ , MgO, Tb ₄ O ₇ or Sm ₂ O.
_{The present} invention relates to a dielectric porcelain composition containing ₃ , MnO, and particularly to a dielectric porcelain composition most suitable for a ceramic capacitor.

[0002]

2. Description of the Related Art Hitherto, dielectric ceramic compositions have been used as materials for multilayer ceramic capacitors and the like. Such a multilayer ceramic capacitor is formed by laminating a plurality of raw sheets of the dielectric ceramic composition on which internal electrodes are formed so as to have a predetermined capacity, and then firing them integrally. For example, X7R (EIA standard: temperature characteristic of capacitance is -55
(± 15% at 125 ° C. to 125 ° C.), the dielectric ceramic composition used at + 25 ° C.
It is important that the relative dielectric constant is as high as 2500 or more, the thickness of a raw sheet per sheet is 15 μm or less, and the firing temperature is, for example, 1300 ° C. or less.

That is, the relative dielectric constant at 25 ° C. is 2500
As described above, by setting the thickness of the raw sheet to 15 μm or less, the thickness and the facing area of the raw sheet between the internal electrodes can be minimized, and the miniaturization of the multilayer ceramic capacitor can be achieved. Further, by setting the firing temperature to 1300 ° C. or lower, the selection range of the material of the internal electrode increases, and for example,
Inexpensive Pd-Ag can be used from expensive Pd 100% material. In addition to the above, the dielectric loss tan δ and the insulation resistance, which are various characteristics of the dielectric ceramic composition, must be sufficiently considered, and it is desired that the AC loss has a small AC voltage dependence.

Conventionally, as a material having an improved relative dielectric constant,
A dielectric porcelain composition containing BaTiO ₃ , Nb ₂ O ₅ , and ZnO has already been proposed (JP-A-59-18162).
And JP-A-59-18159). According to such a dielectric porcelain composition, the relative dielectric constant is 2000
３3000. However, even though the above-mentioned dielectric porcelain composition can obtain a high relative dielectric constant, the dielectric loss tan δ is large, so that the raw sheet cannot be thinned. Dielectric constant was not obtained.

As systems developed to reduce the dielectric loss tan δ, BaTiO ₃ , Nb ₂ O ₅ , MgO,
The dielectric ceramic composition comprising la ₂ O ₃ has been already proposed (see Japanese Patent Kokoku 5-10766). Also, Ba
A composition in which Nb ₂ O ₅ and MgO are added to TiO _{3 so} that the molar ratio of Nb ₂ O ₅ / MgO is in the range of 2.3 to 4, and 0.1 to 0.5% by weight of rare earth is added thereto. (See Japanese Patent Publication No. 55-19007).

[0006]

However, none of the above-mentioned dielectric ceramics has a relative dielectric constant as small as about 2200 or less, and cannot cope with an increase in size and capacity. There is also a problem that the dielectric loss is still large and it is difficult to make the raw sheet thin.

Further, in any of the above-described dielectric ceramics, the AC voltage dependence of the dielectric loss increases to 3.0% or more when 2000 V / cm is applied, and it is impossible to cope with the thinning of the dielectric. In this case, there is a problem that it is impossible to cope with a reduction in the size and the capacity of the capacitor.

[0008]

The present inventors have made intensive studies in view of the above problems and found that barium titanate BaT
Mainly composed of iO ₃ , Nb ₂ O ₅ , MgO, Tb ₄ O ₇ or Sm ₂ O ₃ , MnO, SiO ₂ and / or Al ₂ O ₃
Is contained in a predetermined composition ratio, and by setting the molar ratio of Nb ₂ O ₅ to MgO to 0.5 to 2.2, the relative dielectric constant is 2500 or more, and the temperature change rate of the capacitance is EIA.
Dielectric that satisfies standard X7R, has a small dielectric loss of 2.5% or less, and has a small dielectric loss of 3.0% or less even when an AC voltage of 2000 V / cm is applied, and has a small AC voltage dependency, and can be made thinner The present inventors have found that a body porcelain can be obtained, and have reached the present invention.

That is, the dielectric ceramic composition of the present invention comprises Ba
Nb ₂ O ₅ is added in an amount of 0.8 to 100 parts by weight of TiO _3.
2.5 parts by weight, 0.06 to 0.70 parts by weight of MgO, T
b ₄ O ₇ or Sm ₂ O ₃ and 0.005 to 0.520 parts by weight, in terms of MnO to MnCO ₃ 0.01 to 0.30
Parts by weight, at least one of SiO ₂ and Al ₂ O ₃ is contained in an amount of 0.05 to 0.50 parts by weight, and Nb ₂
Molar ratio of MgO O ₅ is intended to be within the scope of 0.5-2.2. Further, it is desirable that ZnO be contained in an amount of 0.5 part by weight or less based on 100 parts by weight of BaTiO ₃ .

In the present invention, Nb ₂ O ₅ is contained in an amount of 0.8 to 2.5 parts by weight with respect to 100 parts by weight of BaTiO ₃ .
This is because the temperature characteristics and the sinterability are poor, and if it exceeds 2.5 parts by weight, the relative dielectric constant decreases, and the temperature characteristics deteriorate significantly. Nb ₂ O ₅ is desirably contained in an amount of 1.3 to 2.0 parts by weight based on 100 parts by weight of BaTiO ₃ .

The reason why the MgO content is set to 0.06 to 0.70 parts by weight is that when the content is less than 0.06 parts by weight, the relative dielectric constant and the insulation resistance are reduced, the temperature characteristics are deteriorated, the grains grow, and the voltage of the dielectric loss is reduced. This is because the dependency becomes large. Also, 0.7
If the amount is more than 0 parts by weight, the relative permittivity decreases and the insulation resistance also decreases. MgO is desirably 0.1 to 0.4 parts by weight.

Further, the reason why Tb ₄ O ₇ or Sm ₂ O ₃ is 0.005 to 0.520 parts by weight is that Tb ₄ O ₇
If the content of Sm ₂ O ₃ is less than 0.005 parts by weight, the relative dielectric constant is lowered, and the sinterability is poor. If the content exceeds 0.520 parts by weight, the temperature characteristics are deteriorated. Tb ₄ O ₇ or S
m ₂ O ₃ is desirably 0.005 to 0.2 parts by weight.

MnO is converted to MnCO ₃ in an amount of 0.01 to
When it is less than 0.01 part by weight, the insulation resistance is reduced, the dielectric loss and the sinterability deteriorate, and
If the amount exceeds 0 parts by weight, the relative permittivity will decrease. MnO is desirably 0.04 to 0.10 parts by weight in terms of MnCO ₃ .

The reason why the molar ratio of Nb ₂ O ₅ to MgO is set to 0.5 to 2.2 is that when the molar ratio is smaller than 0.5, the relative dielectric constant is deteriorated, and the temperature characteristics and sinterability are deteriorated. This is because if it is not good, and if it is larger than 2.2, the temperature characteristic is bad and the relative dielectric constant is lowered. In the present invention, the molar ratio of MgO Nb ₂ O _5, particularly, it is desirable that the 0.6 to 1.4.

[0015] Further, 0.05 to 0.50 parts by weight of at least one of SiO ₂ and Al ₂ O ₃ is contained per 100 parts by weight of BaTiO ₃ when less than 0.05 part by weight. This is because there is almost no effect of improving the relative dielectric constant, the effect of improving the sinterability, and the effect of improving the voltage dependency, and if it is more than 0.50 parts by weight, the relative dielectric constant tends to decrease. At least one of SiO ₂ and Al ₂ O ₃ is desirably contained in an amount of 0.1 to 0.2 parts by weight based on 100 parts by weight of BaTiO ₃ .

Furthermore, the reason that 0.5 parts by weight or less of ZnO is contained with respect to 100 parts by weight of BaTiO ₃ is that when the amount of ZnO is more than 0.5 parts by weight, the temperature characteristics are poor and the dielectric loss tends to increase. Because it is in. ZnO is BaT
It is desirable to contain 0.3 parts by weight or less based on 100 parts by weight of iO ₃ .

BaTiO ₃ used in the present invention is, for example, a BaTiO ₃ powder having an average crystal grain size of 1.0 μm or less produced by any of a solid phase method, a sol-gel method, an oxalic acid method, and a hydrothermal synthesis method. With the main component being BaTiO
₃ Nb ₂ O ₅ , MgO, Tb ₄
O ₇ or _{Sm 2 O 3, MnCO 3,} SiO 2, Al 2
A predetermined amount of each of O ₃ and ZnO powders is weighed, wet-pulverized by a ball mill or the like for 20 to 48 hours, dried, and then added with a predetermined amount of a binder to form a predetermined shape. It is manufactured by firing at a temperature of 1 to 2 hours.

When a multilayer ceramic capacitor is manufactured, the above-mentioned powder is slurried, formed into a sheet by a doctor blade method, and an internal electrode such as Ag-Pd is applied to the sheet-shaped body as appropriate. A plurality of these may be laminated and fired simultaneously under the above firing conditions.

The Nb ₂ O ₅ , MgO,
Tb ₄ O ₇ or Sm ₂ O ₃ , MnCO ₃ , SiO ₂ ,
Instead of each powder of Al ₂ O ₃ and ZnO, Nb, Mg,
Tb or hydroxide of Sm, Mn, Si, Al, Zn,
Carbonates, nitrates, oxalates, alkoxides, and the like that can be decomposed below the sintering temperature to form oxides can also be used.

In order to improve the AC voltage dependency, it is preferable to control the average crystal grain size d of the sintered body to d <1.0 μm. Thus, the average crystal grain size d of the sintered body is set to d <
To control it to 1.0 μm, barium titanate powder having an average crystal grain size of 1.0 μm or less is used as a starting material,
It is necessary to carry out wet pulverization for a long time to control the particle size after pulverization to 0.8 μm or less, or to set the firing temperature as low as possible and to shorten the firing time.

[0021]

According to the dielectric ceramic composition of the present invention, the temperature characteristic of the capacitance is within ± 15% within the range of −55 ° C. to 125 ° C., the relative dielectric constant at + 25 ° C. is 2500 or more, and the thickness of the green sheet is increased. Is 15 μm, the dielectric loss is as small as 2.5% or less, and the AC voltage is 2000 V / cm.
Can be as small as 3% or less. For this reason, a small-sized and large-capacity multilayer capacitor can be obtained. Further, since the sintering temperature is 1300 ° C. or less, it is easy to produce industrially, and inexpensive silver-palladium (Ag / Pd = 20/80 to 40/6) is used for the internal electrode.
Thus, a dielectric porcelain which can be used for a multilayer capacitor using 0) is achieved. Furthermore, dielectric loss, which is a basic characteristic of dielectric porcelain, is 2.5% or less, insulation resistance (IR)
Is sufficiently higher than 10 ⁴ MΩ. Incidentally, the dielectric ceramic composition of the present invention can also be used for resonators.

[0022]

EXAMPLES Examples of the present invention will be described below in detail with reference to Reference Examples. (Reference Example 1)

Average particle size produced by hydrothermal synthesis
The main component is BaTiO ₃ powder of 0 μm or less.
Nb ₂ O ₅ , Mg with respect to 100 parts by weight of aTiO ₃
O, were weighed powders of Tb ₄ O _7, MnCO ₃ as shown in Table 1, was 20-48 hours wet pulverized in a ball mill, adding an organic binder, and thereafter stirred, doctor blade It was formed into a tape having a thickness of 15 μm by the method. This tape is cut into a size of 130 mm × 100 mm and 20 sheets are laminated to produce a laminate.

[0024]

[Table 1]

Incidentally, an Ag-Pd paste (Ag / Pd = 30/70) was printed as an internal electrode. This laminate was cut into 3.2 mm × 1.6 mm and fired in air at 1250 to 1340 ° C. for 2 hours as shown in Table 1. Further, electrodes of silver paste were baked on both end surfaces at 800 ° C. for 10 minutes to obtain measurement samples.

With respect to the sample thus formed,
The capacitance and dielectric loss were measured at a reference temperature of 25 ° C. and a frequency of 1.
The measurement was performed at 0 kHz and a measurement voltage of 1.0 Vrms. Also,
The temperature change rate of the capacity was measured in the range of -55 to + 125 ° C, and the capacity at + 25 ° C was used as a reference. Further, the insulation resistance was measured when a DC voltage of 25 V was applied for one minute. The relative permittivity was calculated back from the capacitance.

The average particle size of the sintered body was calculated by observing the surface of the sintered body at a magnification of 15,000 with a scanning electron microscope and measuring 500 or more particles by a line intercept method. Further, dielectric loss was measured when a voltage of 2000 Vrms / cm was applied at a frequency of 1 kHz. Table 2 shows the above results.

[0028]

[Table 2]

Each of the dielectric ceramics within the scope of the present invention has a relative dielectric constant as large as 2500 or more, and furthermore, the EIA standard X
Satisfies 7R characteristics (capacity change within ± 15% in a temperature range of -55 ° C to 125 ° C). Further, the dielectric loss tan
δ is as small as 2.2% or less, and AC voltage is 2000 Vrms.
/ Cm shows a loss of 2.8% or less. Further, the insulation resistance (IR) is 5 × 10 ⁴ MΩ or more.

In Table 1, Sample Nos. 1 to 5 are Nb ₂ added to BaTiO ₃ which is a main component of the dielectric ceramic composition.
The amount of O ₅ and the value to 0.6 to 2.6 parts by weight respectively varied. At this time, MgO, Tb ₄ O ₇ and MnCO ₃
Was added to 0.2 parts by weight, 0.2 parts by weight, and 0.1 parts by weight.

Sample No. 1 (addition amount of Nb ₂ O ₅ : 0.6
(Parts by weight), the dielectric constant εr is 3710, which is a good product, but the dielectric loss tan δ is 3.6%. Further, the temperature characteristic becomes -20%. In sample numbers 2 to 4 (addition amount of Nb ₂ O ₅ : 0.8 to 2.5 parts by weight), the relative dielectric constant εr was 2670 to 3640,
The dielectric loss tan δ is 2.2% or less and the temperature characteristic is ±
13% or less, the tan δ when an AC voltage of 2000 V / cm is applied is 2.7% or less, and the insulation resistance (IR) is 6 to 8
× 10 ⁴ MΩ, which is a good product range. That is, the relative permittivity εr
High, excellent temperature characteristics, small dielectric loss tanδ,
Furthermore, a dielectric ceramic having a small AC voltage dependence of dielectric loss is achieved. Sample No. 5 (the amount of Nb ₂ O ₅ added:
2.6 parts by weight), the relative permittivity ε is degraded to 2280 and the temperature characteristic is degraded to −19%. Therefore, in the present invention, Nb ₂ O ₅ added to barium titanate BaTiO ₃ is used.
Was in the range of 0.8 to 2.5 parts by weight based on 100 parts by weight of barium titanate BaTiO ₃ .

In Sample Nos. 6 to 10, the amount of MgO added to BaTiO _{3 as} the main component of the dielectric ceramic composition was varied from 0.05 to 0.75 parts by weight. At this time, the added amounts of Nb ₂ O ₅ , Tb ₄ O ₇ , and MnCO ₃ were 0.8 to 2.5 parts by weight, 0.2 parts by weight, respectively.
0.1 parts by weight.

In sample No. 6 (addition amount of MgO: 0.05 parts by weight), the tan at an AC voltage of 2000 V / cm was applied.
δ becomes 4.0%. In addition, sample numbers 7 to 9
(Amount of added MgO: 0.06 to 0.70 parts by weight)
The relative dielectric constant εr becomes 2660-3050, and the dielectric loss t
an σ is 2.0% or less, the temperature characteristics are within ± 12%, tan σ is 2.7% or less when an AC voltage of 2000 V / cm is applied, and the insulation resistance (IR) is 6 to 8 × 10 ⁴ M.
Ω and non-defective range. That is, a dielectric ceramic having a high relative permittivity εr, excellent temperature characteristics, a small dielectric loss tan δ, and a small AC voltage dependence of the dielectric loss is achieved. Further, in sample No. 10 (the amount of added MgO: 0.75 parts by weight), the dielectric loss tan δ is 1.9%, which is a good range, but the relative dielectric constant εr is 2150. Therefore, in the present invention, barium titanate BaT
The weight of MgO added to iO ₃ is barium titanate Ba.
The range was 0.06 to 0.70 parts by weight based on 100 parts by weight of TiO ₃ . Tb ₄ O ₇ Sample No. 11 to 15 to be added to BaTiO ₃ as a main component of the dielectric ceramic composition
Was varied from 0.002 to 0.53 parts by weight.

At this time, Nb ₂ O ₅ , MgO and MnCO
1.8 parts by weight ₃ of the added amount of each of 0.3 part by weight,
0.1 parts by weight.

Sample No. 11 (addition amount of Tb ₄ O ₇ : 0.1
002 parts by weight), the dielectric loss tan δ is 2.3%, but the relative dielectric constant εr is as low as 2420. Sample Nos. 12 to 14 (addition amount of Tb ₄ O ₇ :
0.005 to 0.52 parts by weight), the relative dielectric constant εr is 2
760 to 3590, and the dielectric loss tan δ is 1.8%
And the temperature characteristic is within ± 10%, and tan δ when an AC voltage of 2000 V / cm is applied is 2.8% or less,
The insulation resistance (IR) is 5 to 8 × 10 ⁴ MΩ, which is a range of non-defective products. That is, a dielectric ceramic having a high relative permittivity εr, excellent temperature characteristics, a small dielectric loss tan δ, and a small AC voltage dependence of the dielectric loss is achieved. Further, in sample No. 15 (addition amount of Tb ₄ O ₇ : 0.53 parts by weight), although the relative dielectric constant εr is 3740 and the dielectric loss tan δ is 1.8%, which is a good product range, the temperature characteristic is −20. %. Therefore, the amount of Tb ₄ O ₇ added to the barium titanate BaTiO ₃ in the present invention is to provide Baruumu BaTiO ₃ 100 parts by weight titanate, 0.005
~ 0.52 parts by weight.

In Sample Nos. 16 to 20, the amount of MnCO ₃ added to BaTiO _{3 as} the main component of the dielectric ceramic composition was varied from 0.005 to 0.40 parts by weight.

At this time, Nb ₂ O ₅ , MgO and Tb ₄ O
The addition amount of ₇ was 1.8 parts by weight, 0.3 parts by weight, and 0.2 parts by weight.

Sample No. 16 (addition amount of MnCO ₃ : 0.1
005 parts by weight), the relative dielectric constant εr is 2990, but the dielectric loss tan δ is 2.7%. Further, the insulation resistance becomes 8 × 10 ³ . Sample No. 17
~ 19 (the amount of MnCO ₃ added: 0.01-0.3 parts by weight), the relative dielectric constant εr becomes 2590-2910,
The dielectric loss tan δ is 2.1% or less and the temperature characteristic is ±
Within 8%, and t when applying an AC voltage of 2000 V / cm
an δ is 2.8% or less and insulation resistance (IR) is 6 to 8 ×
This is 10 ⁴ MΩ, which is a good range. That is, a dielectric ceramic having a high relative permittivity εr, excellent temperature characteristics, a small dielectric loss tan δ, and a small AC voltage dependence of the dielectric loss is achieved. Further, sample No. 20 (the amount of MnCO ₃ added:
0.40 parts by weight), the dielectric loss tan δ is 1.6%, which is a good range, but the relative dielectric constant εr is as low as 2160. Thus, the weight of MnCO ₃ added to the barium titanate BaTiO ₃ in the present invention is to provide Baruumu BaTiO ₃ 100 parts by weight titanate,
The range was 0.01 to 0.3 parts by weight.

Sample Nos. 21 to 29 are MgO of Nb ₂ O ₅
Was changed from 0.4 to 2.3. Ratio 0.4
In both cases, the dielectric constant is lower than 2300, 2140 and 2500, and the temperature characteristics are deviated. On the other hand, when the ratio is 0.5-2.
In case 2, the dielectric constant is 2500 or more, and the temperature characteristics and other characteristics are satisfied.

Example 1 Sample No. 1 in Table 1 13, the composition of SiO ₂ , Al ₂ O ₃ ,
ZnO powder was added and contained as shown in Table 3, and formed into a tape in the same manner as in Reference Example 1, and then this tape was laminated to form internal electrodes, thereby producing a laminate. And each characteristic was measured similarly to the reference example 1, and was described in Table 4.

The composition of the sample was such that Nb ₂ O ₅ was 1.8 parts by weight, MgO was 0.3 parts by weight, Tb ₄ O ₇ was 0.2 parts by weight, MnO _{2 was} 100 parts by weight of BaTiO _3. To M
0.1 parts by weight in terms of nCO ₃ , SiO ₂ , Al ₂
O ₃ and ZnO are contained in predetermined amounts with respect to 100 parts by weight of BaTiO ₃ .

[0042]

[Table 3]

[0043]

[Table 4]

From these Tables 3 and 4, it can be seen that SiO ₂ , Al ₂
It can be seen that by containing O ₃ and ZnO, the firing temperature is lower and the dielectric constant is higher than in the case where these compounds are not contained (Sample No. 13).

[0045] (Reference Example 2) as a main component the following BaTiO ₃ powder having an average particle size of 1.0μm produced by hydrothermal synthesis method, the BaTiO ₃ 10
0 parts by weight, Nb ₂ O ₅ , MgO, Sm ₂ O ₃ , Mn
Each powder of CO ₃ was weighed as shown in Table 5 and wet-pulverized by a ball mill for 20 to 48 hours, and then an organic binder was added. Then, the mixture was stirred and the thickness was 15 μm by a doctor blade method.
m. 130mm x 1
The sheet is cut into 00 mm, and 20 sheets are stacked to produce a laminate.

[0046]

[Table 5]

Incidentally, an Ag-Pd paste (Ag / Pd = 30/70) was printed as an internal electrode. This laminate was cut into 3.2 mm × 1.6 mm, and fired in air at 1260 to 1340 ° C. for 2 hours as shown in Table 1. Furthermore, electrodes made of silver paste were baked on both end surfaces at 800 ° C. for 10 minutes to obtain measurement samples.

With respect to the thus formed sample, the capacitance and the dielectric loss were measured at a reference temperature of 25 ° C. and a frequency of 1.0 k.
Hz and a measurement voltage of 1.0 Vrms. The temperature change rate of the capacitance is measured in the range of -55 to + 125 ° C,
Based on the capacity at + 25 ° C. Further, the insulation resistance was measured when a DC voltage of 25 V was applied for one minute.

The relative permittivity was calculated backward from the capacitance.

The average particle size of the sintered body was calculated by observing the surface of the sintered body at a magnification of 15,000 with a scanning electron microscope and measuring 500 or more particles by a line intercept method. Further, dielectric loss was measured when a voltage of 2000 Vrms / cm was applied at a frequency of 1 kHz. Table 6 shows the above results.

[0051]

[Table 6]

Each of the dielectric ceramics within the scope of the present invention has a relative dielectric constant as large as 2500 or more, and furthermore, the EIA standard X
Satisfies 7R characteristics (capacity change within ± 15% in a temperature range of -55 ° C to 125 ° C). Further, the dielectric loss tan
δ is as small as 2.2% or less, and AC voltage is 2000 Vrms.
/ Cm shows a loss of 2.9% or less. Further, the insulation resistance (IR) is 5 × 10 ⁴ MΩ or more.

In Table 5, Sample Nos. 44 to 48 have N added to BaTiO ₃ which is a main component of the dielectric ceramic composition.
The value of b ₂ O ₅ was varied from 0.6 to 2.6 parts by weight. At this time, MgO, Sm ₂ O ₃ and MnC
The added amount of O ₃ was 0.2 parts by weight, 0.2 parts by weight, and 0.1 parts by weight.

Sample No. 44 (addition amount of Nb ₂ O ₅ : 0.
6 parts by weight), the dielectric constant εr is good as 3710, but the dielectric loss tan δ is 3.5%.
Further, the temperature characteristic becomes -18%. In addition, sample numbers 45 to 47 (the addition amount of Nb ₂ O ₅ : 0.8 to 2.5
Parts by weight), the relative dielectric constant εr is 2590 to 3520, the dielectric loss tan δ is 2.1% or less, the temperature characteristic is within ± 12%, and the tan δ when an AC voltage of 2000 V / cm is applied is 2.8. % And the insulation resistance (IR) is 6
８8 × 10 ⁴ MΩ, which is a good product range. That is, a dielectric ceramic having a high relative permittivity εr, excellent temperature characteristics, a small dielectric loss tan δ, and a small AC voltage dependence of the dielectric loss is achieved. Further, in the sample No. 48 (addition amount of Nb ₂ O ₅ : 2.6 parts by weight), the relative dielectric constant ε is deteriorated to 2280 and the temperature characteristic is reduced to −18%. Therefore, in the present invention, Nb added to barium titanate BaTiO ₃
The weight of ₂ O ₅ is barium titanate BaTiO ₃ 100
The range was 0.8 to 2.5 parts by weight with respect to parts by weight.

In Sample Nos. 49 to 53, the amount of MgO added to BaTiO _{3 as} the main component of the dielectric ceramic composition was varied from 0.05 to 0.75 parts by weight. In this _{case, Nb 2 O 5, Sm 2} O 3, and the amount of each 0.8 to 2.5 parts by weight of MnCO _3, 0.2 parts by weight,
0.1 parts by weight.

Sample No. 49 (MgO added amount: 0.05
Parts by weight) are the values of ta when an AC voltage of 2000 V / cm is applied.
nδ becomes 4.4%. In addition, sample number 50 ~
At 52 (the addition amount of MgO: 0.06 to 0.70 parts by weight), the relative dielectric constant εr is 2660 to 2950, the dielectric loss tanσ is 1.8% or less, and the temperature characteristic is ± 12%.
And tan when an AC voltage of 2000 V / cm is applied.
is 2.6% or less and the insulation resistance (IR) is 6 to 8 × 10
The range is ⁴ MΩ, which is a good product. That is, a dielectric ceramic having a high relative permittivity εr, excellent temperature characteristics, a small dielectric loss tan δ, and a small AC voltage dependence of the dielectric loss is achieved. Further, Sample No. 53 (added amount of MgO: 0.7
(5 parts by weight), the dielectric loss tan δ is 1.6%, which is a good product range, but the relative dielectric constant εr is 2190. Therefore, in the present invention, barium titanate Ba
The weight of MgO added to TiO ₃ is barium titanate B
0.06 to 0.70 based on 100 parts by weight of aTiO ₃
It was in the range of parts by weight. Sample Nos. 54 to 58 are Sm ₂ O added to BaTiO ₃ which is a main component of the dielectric ceramic composition.
_{The value of 3} was varied from 0.002 to 0.53 parts by weight.

At this time, Nb ₂ O ₅ , MgO and MnCO
1.8 parts by weight ₃ of the added amount of each of 0.3 part by weight,
0.1 parts by weight.

Sample No. 54 (addition amount of Sm ₂ O ₃ : 0.
002 parts by weight), the dielectric loss tan δ is 2.3%, but the relative dielectric constant εr is as low as 2330. Sample Nos. 55 to 57 (addition amount of Sm ₂ O ₃ :
0.005 to 0.52 parts by weight), the relative dielectric constant εr is 2
680 to 3450, and the dielectric loss tan δ is 1.9%.
And the temperature characteristic is within ± 10%, and tan δ when an AC voltage of 2000 V / cm is applied is 2.8% or less,
The insulation resistance (IR) is 5 to 8 × 10 ⁴ MΩ, which is a range of non-defective products. That is, a dielectric ceramic having a high relative permittivity εr, excellent temperature characteristics, a small dielectric loss tanσ, and a small AC voltage dependence of the dielectric loss is achieved. Further, in the sample No. 58 (addition amount of Sm ₂ O ₃ : 0.53 parts by weight), the relative dielectric constant εr is 3630, the dielectric loss tan δ is 1.8%, which is a good product range, but the temperature characteristic is −20. %. Therefore, the amount of Sm ₂ O ₃ to be added to the barium titanate BaTiO ₃ in the present invention is to provide Baruumu BaTiO ₃ 100 parts by weight titanate, 0.005
~ 0.52 parts by weight.

In Sample Nos. 59 to 63, the amount of MnCO ₃ added to BaTiO _{3 as} the main component of the dielectric ceramic composition was varied from 0.005 to 0.40 parts by weight.

At this time, Nb ₂ O ₅ , MgO and Sm ₂ O
The amounts of ₃ added were 1.8 parts by weight, 0.3 parts by weight, and 0.2 parts by weight.

Sample No. 59 (addition amount of MnCO ₃ : 0.1
005 parts by weight), the relative dielectric constant εr becomes 2870, but the dielectric loss tan δ becomes 2.8%. Further, the insulation resistance becomes 8 × 10 ³ . Sample No. 60
-62 (the amount of MnCO ₃ added: 0.01-0.3 parts by weight), the relative dielectric constant εr becomes 2520-2820,
The dielectric loss tan δ is 2.2% or less and the temperature characteristic is ±
Within 9%, and t when applying an AC voltage of 2000 V / cm
an δ is 2.9% or less and insulation resistance (IR) is 6 × 10
⁴ to 8 × 10 ⁴ MΩ, which is a good range. That is, a dielectric ceramic having a high relative permittivity εr, excellent temperature characteristics, a small dielectric loss tan δ, and a small AC voltage dependence of the dielectric loss is achieved. Further, in sample No. 63 (addition amount of MnCO ₃ : 0.40 parts by weight), the dielectric loss tan δ was 1.6%, which is a good range, but the relative dielectric constant εr was 2%.
It is as low as 190. Thus, the weight of MnCO ₃ added to the barium titanate BaTiO ₃ in the present invention is to provide Baruumu BaTiO ₃ 100 parts by weight titanate, ranged from 0.01 to 0.3 parts by weight.

Sample Nos. 64 to 72 are MgO of Nb ₂ O ₅
Was changed from 0.4 to 2.3. Ratio 0.4
In both cases, the dielectric constant is lower than 2300, 2210 and 2500, and the temperature characteristics are deviated. On the other hand, when the ratio is 0.5-2.
In case 2, the dielectric constant is 2500 or more, and the temperature characteristics and other characteristics are satisfied.

(Example 2) 56 composition, SiO ₂ , Al ₂ O ₃ ,
ZnO powder was added and contained as shown in Table 7, and formed into a tape shape in the same manner as in Reference Example 2, and then the tapes were laminated to form internal electrodes, thereby producing a laminate. And each characteristic was measured similarly to the reference example 2, and was described in Table 8.

The composition of the sample was such that Nb ₂ O ₅ was 1.8 parts by weight, MgO was 0.3 parts by weight, Sm ₂ O ₃ was 0.2 parts by weight, MnO _{2 was} 100 parts by weight of BaTiO _3. To M
0.1 parts by weight in terms of nCO ₃ , SiO ₂ , Al ₂
O ₃ and ZnO are contained in predetermined amounts with respect to 100 parts by weight of BaTiO ₃ .

[0065]

[Table 7]

[0066]

[Table 8]

From these Tables 7 and 8, it can be seen that SiO ₂ , Al ₂
It can be seen that by containing O ₃ and ZnO, the firing temperature is lower and the relative dielectric constant is higher than when these compounds are not contained (sample No. 56).

[0068]

As described above, according to the present invention, X7R
The characteristics are satisfied, the relative dielectric constant εr is 2500 or more, and the firing temperature is 1300 ° C. or less. Further, as other characteristics, the dielectric loss tan δ is 2.5% or less and the insulation resistance (I
R) is 10 ⁴ MΩ or more, and a dielectric ceramic composition having a tan δ of 3% or less when an AC voltage of 2000 V / cm is applied can be obtained.

Thus, for example, when a multilayer ceramic capacitor is made of the above-described dielectric ceramic composition, a small-sized and large-capacity capacitor excellent in temperature characteristics can be obtained, and the firing temperature is 1300 ° C. or less, and Inexpensive silver-palladium can be used as internal electrodes between the sheets, and an inexpensive multilayer ceramic capacitor can be obtained.

Continuation of front page (56) References JP-A-3-112859 (JP, A) JP-A-61-99208 (JP, A) JP-A-8-183658 (JP, A) JP-A-8-119728 (JP, A) , A) JP-A-8-151260 (JP, A) JP-A-7-187780 (JP, A) (58) Fields studied (Int. Cl. ⁷ , DB name) C04B 35/42-35/50 CA (STN) REGISTRY (STN)

Claims (2)

(57) [Claims] (1) 100 parts by weight of BaTiO ₃ and Nb ₂
O ₅ and 0.8 to 2.5 parts by weight, the MgO .06 to 0.
70 parts by weight of Tb ₄ O ₇ or Sm ₂ O ₃
0.520 parts by weight, MnO is converted to MnCO ₃ to 0.10 parts by weight.
01 to 0.30 parts by weight, with containing 0.05 to 0.50 parts by weight of at least one of SiO ₂ and Al ₂ O _3, 0.5 to the molar ratio of MgO of Nb ₂ O ₅
2.2. A dielectric porcelain composition characterized by being in the range of 2.2. 2. A ZnO based on 100 parts by weight of BaTiO _3.
2. The dielectric ceramic composition according to claim 1, wherein O is contained in an amount of 0.5 part by weight or less.