JP2000313659A - Dielectric ceramic composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a dielectric ceramic composition, in which a temperature- changing ratio of electrostatic capacity satisfies NPO characteristic, exhibiting good electrical characteristic having >=60 permittivity and >=900 Q value and capable of sintering at a low sintering temperature of 950 deg.C to 1050 deg.C. SOLUTION: In this dielectric ceramic composition, the main component is represented by the formula aBaTi4O9-bTiO2-cNd2O3-dSm2O3-eLa2O3-fGd2O3- gCaO-hSrO wherein 84.0>=a>=53.9, 9.8>=b>=0.0, 43.0>=c>=10.2, 14.5>=d>=0.0, 0.2>=e>=0.0, 18.5>=f>=0.0, 1.4>=g>=0.0 and 1.0>=h>=0.0 when(a+b+c+d+e+f+g+h) is defined as 100 wt.% and the subsidiary component is represented by the formula iBi2O3-jPbO-kB2O3-lSiO2-mLi2CO3-nZnO-oGeO2-pBaCO3-qBaSiZnO4 wherein 5.8>=i>=0.0, 7.5>=j>3.0, 0.7>=k>=0.0, 1.0>=l>=0.0, 0.2>=m>=0.0, 5.0>n>=0.0, 5.0>o>=0.0, 1.9>=p>=0.0 and 1.8>=q>=0.0 based on main component.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a dielectric porcelain composition, and more particularly to a dielectric porcelain composition used as a material for a dielectric resonator used in a microwave region or a dielectric for temperature compensation.

[0002]

2. Description of the Related Art With the rapid progress of miniaturization, high functionality, and low price of high-frequency devices such as mobile phones in recent years, dielectric resonators used in these high-frequency devices have been similarly miniaturized and have high performance. What is desired is a low-priced one. The dielectric porcelain composition used as a material for these dielectric resonators and the like is required to have a characteristic having a high relative dielectric constant, a high Q value, and a low temperature dependence of capacitance. This is because a high relative dielectric constant facilitates the miniaturization of the resonator, and a high Q value decreases the dielectric loss of the resonator. This is because such a change in the characteristic as described above can be suppressed. In particular, it is preferable that the temperature characteristics of the capacitance satisfy the NPO characteristics defined by the EIA standard. NPO
The characteristic means a characteristic in which the temperature change rate of the capacitance is flat within ± 0.3% over a wide range of −55 to 125 ° C. with reference to the capacitance at + 25 ° C.

[0003] As a dielectric porcelain composition satisfying such characteristics, Japanese Patent Laid-Open Publication No. Hei 7-187, Japanese Patent Publication No.
No. 773 discloses a dielectric porcelain composition using a substituted barium-neodymium-titanium-perovskite. Further, the dielectric porcelain composition has a substituted barium-
It is also disclosed that when silicon dioxide is added to neodymium-titanium-perovskite as an additive, sintering at a low temperature of 1400 ° C. or less is possible. The ability to sinter at a low temperature to produce a dielectric porcelain composition is very important for reducing the cost of the dielectric porcelain composition. If the sintering temperature is high, the power cost increases, a high-temperature furnace is required, and a setter for putting the material of the dielectric ceramic composition into the high-temperature furnace, a sheath, and the like also need to withstand high temperatures. This is because equipment investment becomes enormous.

When a dielectric ceramic composition is used as a multilayer ceramic capacitor, inexpensive Ag or expensive metal is used instead of expensive metals such as Pd, Pt, and Au conventionally used as internal electrodes. It is known that mixing Ag in a large amount is effective for cost reduction. Ag has a melting point of 1000 ° C compared to expensive metals such as Pd
Therefore, low-temperature sintering is desirable in order to use inexpensive Ag as an internal electrode.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in view of such circumstances, and it is an object of the present invention to provide a high dielectric constant and a high Q value, satisfy NPO characteristics, and maintain a high sintering temperature. Is to provide a dielectric ceramic composition which can be sintered at a low temperature of 950 to 1050 ° C.

[0006]

The dielectric porcelain composition according to the present invention is characterized by having the components described in the claims.

The present inventors have proposed a low-temperature sintering method in which the relative dielectric constant is 60 or more, the Q value is 900 or more, the temperature dependency of the capacitance satisfies the NPO characteristic, and the sintering temperature is 950 to 1050 ° C. As a result of conducting research and experiments with the aim of obtaining a porcelain composition capable of performing the above, it has been found that the above-described dielectric porcelain composition of the present invention achieves this goal.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, a method for producing a dielectric ceramic composition according to the present invention will be described, and electric characteristics of the dielectric ceramic composition produced by the production method and a table showing compositions of these ceramic compositions will be described. Then, an embodiment of the present invention will be described in detail.

One preferred embodiment of the present invention is a dielectric ceramic composition used for a single-plate type ceramic capacitor.

The main component of the porcelain composition according to the present invention was prepared as follows. BaTi4O9 is, BaCO ₃ and TiO ₂
Was used as a starting material, weighed so as to obtain a desired composition, wet-mixed for 3 hours using yttria-stabilized zirconia balls using water as a solvent, and then dried. The obtained mixed powder was calcined at 1050 ° C. for 2 hours, wet-pulverized for 3 hours using yttria-stabilized zirconia balls using water as a solvent, and then dried. The obtained BaTi4O9 and Nd2O3, TiO2, Sm
After weighing 2O3, La2O3, Gd2O3, CaCO3, and SrCO3 as starting materials so as to obtain a target composition, the mixture was wet-mixed for 3 hours using yttria-stabilized zirconia balls using water as a solvent, and dried. The obtained mixed powder is 1200 ° C
After calcination for 2 hours, wet grinding using a ball of yttria-stabilized zirconia using water as a solvent for 3 hours, followed by drying,
The main component was obtained.

The accessory component of the porcelain composition according to the present invention was added to the main component as follows. BaSiZnO4 is
BaCO3, SiO2 and ZnO were prepared in the same manner as BaTi4O9 as starting materials. BaSiZnO4 and Bi2O3, PbO, B2O obtained
3, SiO2, Li2CO3, ZnO, GeO2 and BaCO3 were added to the above main components of the porcelain composition at varying amounts, and wet-mixed for 20 hours using water as a solvent and a ball of yttria-stabilized zirconia.

The mixed powder thus obtained was granulated by adding PVA as an organic binder. Using the powder thus prepared, a press molding machine was used to apply a surface pressure of 3
After a uniaxial pressure molding of a disk-shaped sample having a size of 16.5 mmΦ and a thickness of 0.7 mm at ton / cm 2,
Sintering was performed at 1050 ° C. for 2 hours in the air. After firing, a silver paste was applied to both surfaces of the ceramic sintered body and baked at 750 ° C. in the air to form external electrodes.

The relative permittivity (εr) and Q value of the thus obtained sintered single-plate type capacitor samples were 1 MH.
The measurement was performed using an automatic bridge type measuring instrument under the conditions of z and 1 Vrms. In addition, temperature dependence of capacitance (TC) (ppm /
° C) is -5 with respect to the capacitance at + 25 ° C.
The temperature dependence of the capacitance at 5 to + 125 ° C was determined. Table 1 shows the characteristics of the sintered single-plate capacitor thus obtained.

[Table 1]

The main component, BaTi4O9, is preferably in the range of 53.9% by weight to 84.0% by weight. 8
If the content is more than 4.0% by weight, the temperature dependency of the capacitance does not satisfy the NPO characteristic as in, for example, Sample 5. 5
If the amount is less than 3.9% by weight, the relative dielectric constant and the Q value are reduced, which adversely affects the electrical characteristics. Furthermore, the main component BaTi4O9
Is preferably in the range of 55% by weight or more and 65% by weight or less. This is because within this range, the sintering temperature is further lowered, and the electrical characteristics are improved.

The content of TiO2 as a main component is preferably 9.8% by weight or less. If the content is more than 9.8% by weight, the temperature dependence of the capacitance does not satisfy the NPO characteristic as in Samples 4, 7, and 8, for example, and the relative dielectric constant and Q value decrease, which adversely affects the electrical characteristics. give.

The main component Nd2O3 is 10.2% by weight or more.
It is preferably in the range of 3.0% by weight or less. 4
If the content is more than 3.0% by weight, sintering at a high temperature of 1150 ° C. for 2 hours or more is required to obtain desired electric characteristics. If the content is less than 10.2% by weight, the temperature dependence of the capacitance similarly does not satisfy the NPO characteristic like the sample 5. Furthermore, the main component Nd2O3 is 24% by weight.
It is preferable that the content be in the range of at least 32% by weight. This is because within this range, the sintering temperature is further lowered, and the electrical characteristics are improved.

The main component Sm2O3 is preferably 14.5% by weight or less. If the content is more than 14.5% by weight, the relative dielectric constant and the Q value decrease, which adversely affects the electrical characteristics. Further, the main component Sm2O3 is preferably in the range of 8% by weight or more and 12% by weight or less. This is because within this range, the sintering temperature is further lowered, and the electrical characteristics are improved.

The content of La2O3 as a main component is preferably 0.2% by weight or less. If the content is more than 0.2% by weight, sintering at a high temperature of 1100 ° C. or more and at a high temperature for 2 hours or more is required to obtain desired electric characteristics.

Gd2O3 as a main component is preferably 18.5% by weight or less. If it is more than 18.5% by weight, the relative dielectric constant and the Q value decrease, which adversely affects the electrical characteristics. In order to obtain the desired electrical characteristics, sintering at a high temperature of 1100 ° C. or more for 2 hours or more is required. Because.

The main component CaO is preferably at most 1.4% by weight. If the content is more than 1.4% by weight, sintering at a high temperature of 1100 ° C. or more and at a high temperature for 2 hours or more is required to obtain desired electric characteristics.

The main component SrO is preferably at most 1.0% by weight. If the content is more than 1.0% by weight, sintering at 110 ° C. or more and at a high temperature for 2 hours or more is required to obtain desired electric characteristics.

The additive Bi2O3 is preferably 5.8% by weight or less. If it is more than 5.8% by weight, for example, Samples 4, 8,
As shown in 11, 13, and 14, the temperature dependence of the capacitance does not satisfy the NPO characteristics, the relative permittivity and the Q value are reduced, and the electric characteristics are adversely affected.

It is preferable that the additive PbO is in the range of more than 3.0% by weight and not more than 7.5% by weight. 7.
If the content is more than 5% by weight, the temperature dependence of the capacitance does not satisfy the NPO characteristic as in Samples 4, 8, 11, 13 and 14, and the relative dielectric constant and Q value are reduced, thereby adversely affecting the electrical characteristics. give. If it is less than 3.0% by weight, for example, sample 25
As described above, sintering at a high temperature of 1100 ° C. or more for 2 hours or more is required to obtain desired electric characteristics. Further, the additive PbO is preferably in the range of 5.0% by weight or more and 7.5% by weight or less. This is because within this range, the sintering temperature is further lowered, and the electrical characteristics are improved.

The additive B2O3 is preferably 0.7% by weight or less. If the content is more than 0.7% by weight, for example, the sample 12, 1
As in 3, 14, 19 and 22, the temperature dependence of the capacitance does not satisfy the NPO characteristic, the relative dielectric constant and the Q value are reduced, and the electric characteristics are adversely affected. In addition, the additive B2O3
Is preferably in the range of 0.3% by weight or more and 0.7% by weight or less. This is because within this range, the sintering temperature is further lowered, and the electrical characteristics are improved.

The content of SiO 2 as an additive is preferably 1.0% by weight or less. If the content is more than 1.0% by weight, the temperature dependence of the capacitance does not satisfy the NPO characteristics, the relative dielectric constant and the Q value decrease, and the electric characteristics are adversely affected.

The additive Li2CO3 is preferably 0.2% by weight or less. If the content is more than 0.2% by weight, the temperature dependence of the capacitance does not satisfy the NPO characteristic as in the case of the samples 21 and 22, for example, so that the Q value is reduced and the electrical characteristics are adversely affected.

Preferably, the additive ZnO is less than 5.0% by weight. If the content is 5.0% by weight or more, for example, sample 2
As shown in 3, the relative dielectric constant and the Q value are reduced, which adversely affects the electrical characteristics. Further, ZnO of the additive is preferably in a range of 0.3% by weight or more and 1.0% by weight or less. This is because within this range, the sintering temperature is further lowered, and the electrical characteristics are improved.

Preferably, the additive GeO2 is less than 5.0% by weight. If it is more than 5.0% by weight, for example, sample 2
As shown in No. 4, the temperature dependence of the capacitance does not satisfy the NPO characteristic, the relative dielectric constant and the Q value are reduced, and the electric characteristics are adversely affected. Further, GeO2 of the additive is preferably in the range of 2.0% by weight or more and 4.0% by weight or less. This is because within this range, the sintering temperature is further lowered, and the electrical characteristics are improved.

The BaCO3 additive is preferably 1.9% by weight or less. If the content is more than 1.9% by weight, the temperature dependence of the capacitance does not satisfy the NPO characteristics, and sintering at a high temperature of 1100 ° C. or more for 2 hours or more is required to obtain desired electric characteristics. It is.

The content of BaSiZnO4 as an additive is preferably 1.8% by weight or less. If the content is more than 1.8% by weight, the temperature dependence of the capacitance does not satisfy the NPO characteristic, for example, as in Samples 12 and 14, the relative dielectric constant decreases, and the electrical characteristics are adversely affected.

Another preferred embodiment of the present invention is a dielectric ceramic composition used for a multilayer ceramic capacitor.

In the same manner as described above, the main and auxiliary components BaSiZnO4 of the porcelain composition according to the present invention were obtained. Bi2O3, PbO, B2O3, SiO2,
Li2CO3, ZnO, GeO2, BaCO3 and the obtained BaSiZnO4 were added at varying amounts, and wet mixing was performed for 20 hours using a ball of yttria-stabilized zirconia using water as a solvent. An organic binder is added to the obtained mixed powder,
The ceramic slip was adjusted by wet mixing. The ceramic slip was formed into a sheet by a doctor blade method to obtain a rectangular green sheet having a thickness of 21 μm. Next, Pd and Ag are placed on this ceramic green sheet.
A conductive paste, which is a mixture of the above, was printed to form internal electrodes. A plurality of the ceramic green sheets on which the internal electrodes were formed were stacked such that the sides from which the conductive paste layers were drawn out were alternated to obtain a stacked body.
The laminate was fired in air at 950 to 1050 ° C. for 2 hours. After firing, silver paste was applied to both sides of the ceramic sintered body and baked at 750 ° C. in the air to form external electrodes electrically connected to the internal electrodes.

The external dimensions of the multilayer ceramic capacitor obtained as described above are 3.2 mm in width and 1.6 m in length.
m and thickness 0.5 mm. The thickness of each dielectric ceramic layer interposed between the internal electrodes was 10 μm, and the total number of effective dielectric ceramic layers was 5. The characteristics of the dielectric ceramic composition thus obtained may be sintering at a sintering temperature of 950 to 1050 ° C. for 2 hours, a dielectric constant of 60 or more, a Q value of 900 or more, and an electrostatic property. The temperature change rate of the capacity was 30 ppm / ° C. or less.

[0035] In the embodiment described above, was used BaTi4O9 as one of the main component of the dielectric ceramic composition, instead of BaTi4O9, may be used BaO and TiO _2. When BaO and TiO ₂ are used, the content of BaO is preferably in the range of 17.5% by weight to 27.2% by weight. TiO ₂ is preferably in the range of 36.4% by weight or more and 62.6% by weight or less.

As described above, according to the present invention, the temperature change rate of the capacitance satisfies the NPO characteristic and the relative dielectric constant is 6
A multilayer ceramic capacitor having a good electrical property of 0 or more and a Q value of 900 or more was produced at a low sintering temperature of 950 ° C to 1050 ° C.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H01B 3/12 319 H01B 3/12 319 326 326 335 335 H01G 4/12 358 H01G 4/12 358 415 415 H01P 7/10 H01P 7/10 F term (reference) 4G031 AA01 AA04 AA05 AA06 AA07 AA09 AA11 AA26 AA27 AA28 AA30 AA32 AA35 BA09 5E001 AB01 AB03 AE01 AE02 AE03 AE04 AH09 AJ02 5G303 AA01 CB03 CB15 CB16 CB22 CB25 CB30 CB32 CB35 CB38 CB41 CB42 5J006 HC07 LA25

Claims (2)

[Claims] The main component is BaTi4O9, TiO2, Nd2O3, Sm2O3,
La2O3, Gd2O3, CaO, SrO
i2O3, PbO, B2O3, SiO2, Li2CO3, ZnO, GeO2, BaCO3, B
A dielectric ceramic composition containing aSiZnO4, wherein the main component is a composition formula aBaTi4O9-bTiO2-cNd2O3-dSm2O3-eLa2O3-fGd2O3
When expressed as -gCaO-hSrO, assuming that a + b + c + d + e + f + g + h = 100% by weight, their contents are 84.0 ≧ a ≧ 53.9, 9.8 ≧ b ≧ 0.
0, 43.0 ≧ c ≧ 10.2, 14.5 ≧ d ≧ 0.0, 0.2 ≧ e ≧ 0.0, 18.5
≧ f ≧ 0.0, 1.4 ≧ g ≧ 0.0, 1.0 ≧ h ≧ 0.0, while the subcomponent has the composition formula iBi2O3-jPbO-kB2O3-lSiO2-mLi2CO3-nZnO
In the case of -oGeO2-pBaCO3-qBaSiZnO4, the respective weight percentages of the main components are 5.8 ≧ i ≧ 0.0, 7.5 ≧ j> 3.0,
0.7 ≧ k ≧ 0.0, 1.0 ≧ l ≧ 0.0, 0.2 ≧ m ≧ 0.0, 5.0> n ≧ 0.
0, 5.0> o ≧ 0.0, 1.9 ≧ p ≧ 0.0, 1.8 ≧ q ≧ 0.0. 2. The main component is BaO, TiO2, Nd2O3, Sm2O3, La2
O3, Gd2O3, CaO, SrO, and Bi2O
3, PbO, B2O3, SiO2, Li2CO3, ZnO, GeO2, BaCO3, BaSi
A dielectric ceramic composition containing ZnO4, wherein the main component has a composition formula of aBaO-bTiO2-cNd2O3-dSm2O3-eLa2O3-fGd2O3-gCaO-hS
In terms of rO, assuming that a + b + c + d + e + f + g + h = 100% by weight, the respective contents are 27.2 ≧ a ≧ 17.5, 62.6 ≧ b ≧ 36.4, 43.0
≧ c ≧ 10.2, 14.5 ≧ d ≧ 0.0, 0.2 ≧ e ≧ 0.0, 18.5 ≧ f ≧ 0.
0, 1.4 ≧ g ≧ 0.0, 1.0 ≧ h ≧ 0.0, while the sub-component is represented by the composition formula iBi2O3-jPbO-kB2O3-lSiO2-mLi2CO3-nZnO-oGeO2
In the case of -pBaCO3-qBaSiZnO4, the weight percentage of each of the main components is 5.8 ≧ i ≧ 0.0, 7.5 ≧ j> 3.0, 0.7 ≧
k ≧ 0.0, 1.0 ≧ l ≧ 0.0, 0.2 ≧ m ≧ 0.0, 5.0> n ≧ 0.0, 5.0>
A dielectric porcelain composition, wherein o ≧ 0.0, 1.9 ≧ p ≧ 0.0, 1.8 ≧ q ≧ 0.0.