JPH0676627A - Dielectric ceramic composition - Google Patents

Abstract

PURPOSE:To make sintering at low temperature possible and make a dielectric ceramic composition usable in a high frequency region by containing BaO+ TiO2+ReO3/2 as a main component and containing group II metal oxide. B2O3, and Li2O in the dielectric ceramic composition. CONSTITUTION:After BaCO3, TiO2, and Nd2O3 are wet-mixed and dried, presintered in air at 1000-1200 deg.C to give a main component; xBaO+ yTiO2+zReO3/2 (0.02<=x<=0.3, 0.4<=y<=0.85, 0.05<=z<=0.5, x+y+z=1, Re stands for one or more rare earth elements selected from La, Pr, Nd, Sm, Gd, Py, Er, and Yb). With 20-70wt.% of the main component, 10-55wt.% of SiO2, 1-40wt.% of one or more group II metal oxides selected from CaO, SrO, BaO, and ZnO, 3-30wt.% of B2O3, and 0.1-3.0wt.% of Li2O are mixed and presintered.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dielectric ceramic composition for use in high frequency laminated ceramic capacitors, dielectric resonators and the like.

[0002]

2. Description of the Related Art For example, BaO + TiO ₂ + ReO (where Re is a rare earth element) is known as a dielectric capacitor used in a high frequency region such as MHz and GHz and a dielectric resonator.

[0003]

By the way, the conventional Ba
The firing temperature of O + TiO ₂ + ReO porcelain is 1100 to 15
Since it is relatively high at 00 ° C., a conductive paste containing Pd having a high melting point as a main component had to be used as an internal electrode material when manufacturing a laminated ceramic capacitor. However, Pd has the drawback that the Q of the capacitor is lowered due to its high resistivity and that it is expensive.

Therefore, an object of the present invention is to provide a dielectric ceramic composition which can be manufactured by firing at 900 ° C. or lower and can be used in a high frequency range.

[0005]

The present invention for achieving the above-mentioned object is xBaO + yTiO ₂ + zReO _3/2 where x, y and z are 0.02 ≦ x ≦ 0.3 and 0.4 ≦ y
≦ 0.85, 0.05 ≦ z ≦ 0.5, numerical values satisfying x + y + z = 1, Re is La, Pr, Nd, Sm, Gd,
20 to 70% by weight of a main component consisting of one or more rare earth elements selected from Dy, Er and Yb, and 10 to 55
Wt% SiO ₂ , 1-40 wt% CaO, Sr
A Group 2 metal oxide selected from O, BaO and ZnO;
The present invention relates to a dielectric ceramic composition containing 3 to 30% by weight of B ₂ O ₃ and 0.1 to 3.0% by weight of Li ₂ O.

[0006]

FUNCTION AND EFFECT OF THE INVENTION SiO ₂ and C in the present invention
A Group 2 metal oxide selected from aO, SrO, BaO and ZnO, B ₂ O ₃ and Li ₂ O contribute to obtain a practical relative permittivity ε _r and Q in a high frequency region. In addition, it contributes to reduce the temperature coefficient of the relative dielectric constant, and further contributes to enable firing at 900 ° C. or lower. According to the composition specified in the present invention, the relative permittivity ε _r
Is 6.7 or more, Q is 1000 or more, and the temperature coefficient Tε of the relative permittivity is −25 ° C. to 20 ° C. and 20 ° C. to + 85 ° C., thereby obtaining a dielectric ceramic of −60 ppm / ° C. to +60 ppm / ° C. In addition, this dielectric ceramic can be fired at 900 ° C. or lower.

[0007]

[First Embodiment] Next, a high-frequency ceramic capacitor according to an embodiment of the present invention and a method of manufacturing the same will be described. First, x
In order to obtain a main component satisfying BaO + yTiO ₂ + zReO _3/2 , BaCO ₃ (barium carbonate), TiO 2
₂ (titanium oxide), La ₂ O ₃ (lanthanum oxide), Pr
₂ O ₃ (praseodymium oxide), Nd ₂ O ₃ (neodymium oxide), Sm ₂ O ₃ (samarium oxide), Gd ₂ O ₃ (gadolinium oxide), Dy ₂ O ₃ (dysprosium oxide), Er ₂ O ₃ (oxidation) Erbium) and Yb ₂ O ₃ (ytterbium oxide) were prepared so as to obtain a plurality of compositions shown in Tables 1 and 2. In Tables 1 and 2, the x column shows the BaO molar ratio, the y column shows the TiO ₂ molar ratio, and the z column shows the ReO _3/2 molar ratio. In addition, the dielectric ceramics according to the present invention include SiO ₂ , CaO, and Sr.
To obtain O, BaO, ZnO, B ₂ O ₃ , and Li ₂ O, SiO ₂ (silicon oxide), CaCO ₃ (calcium carbonate), SrCO ₃ (strontium carbonate), and BaC
O ₃ (barium carbonate), ZnO (zinc oxide), B ₂
O ₃ (boron oxide) and Li ₂ CO ₃ (lithium carbonate)
Were prepared in such a proportion that the compositions shown in Tables 1 and 2 could be obtained. Thereafter, these were used to prepare the porcelain capacitors of Sample Nos. 1 to 43 in Tables 1 and 2.

[0008]

[Table 1]

[0009]

[Table 2]

Next, the method for manufacturing the porcelain capacitor of sample No. 1 in Table 1 will be described in detail. First, x = 0.
0.3 BaO + according to 3, y = 0.65, z = 0.05
BaCO ₃ , TiO _2, and Nd ₂ O ₃ were weighed so that 0.65 TiO ₂ + 0.05ReO _3/2 could be obtained, put into a polyethylene pot with water, wet mixed, dehydrated and dried. 1000 this dried product in the atmosphere
It was calcined at ~ 1200 ° C for 2 hours. By this calcination, B
aCO ₃ and Nd ₂ O ₃ become oxides, and the composition of the main component is obtained.

On the other hand, 30 wt% of SiO ₂ which is a component other than the main component (hereinafter referred to as a subcomponent) of 40 wt% and Ba
O, 10% by weight, ZnO, 10% by weight, B ₂ O ₃ , 9% by weight and Li ₂ O, 1% by weight so that SiO ₂ , BaCO ₃ , ZnO, B ₂ O ₃ , Li ₂
O ₃ was weighed, put in a polyethylene pot together with water, wet-mixed, dehydrated and dried. This mixture was calcined in air at 850 ° C. for 2 hours. By this calcination, BaCO ₃ and Li ₂ CO ₃ are converted into oxides, and a composition of subcomponents is obtained.

Next, the calcined product of the main component and the calcined product of the subcomponent were weighed so as to have the composition of sample No. 1 in Table 1, put in a polyethylene pot with water, wet-mixed, dehydrated,
A raw material powder was obtained by drying. Next, an organic binder is added to this powder to granulate, and the granulated product is pressure-molded into a disk shape having a diameter of 9.8 mm and a thickness of 0.6 mm at a pressure of 500 kg / cm ² to obtain a molded product. Obtained. Next, this molded product is placed on a zirconia setter and placed in air (in an oxidizing atmosphere) for 900
It was fired at a temperature of ° C. The composition of the porcelain obtained by this firing has the composition shown in sample No. 1 of Table 1.

Next, in order to obtain the porcelain capacitor 10 shown in FIG. 1, silver paste is applied to both main surfaces of the disk-shaped dielectric porcelain substrate 12 obtained by firing and baked to form a pair of capacitor electrodes. 14 and 16 were formed.

Next, the relative permittivity ε _r and Q of the completed ceramic capacitor 10 and the temperature coefficient of the relative permittivity were determined. As shown in the column of sample No. 1 in Table 3, ε _r was 11. 5, Q
Is a temperature coefficient T ε in the range of 1600, −25 to + 20 ° C.
-25 was -53 ppm / ° C, and the temperature coefficient Tε + 85 in the range of +20 to 85 ° C was -50 ppm / ° C. The relative permittivity ε _r and Q were measured under the condition that a voltage of 20 ° C., 1 MHz, and 1 V was applied between the electrodes 14 and 16. Moreover, the temperature coefficient of the relative permittivity Tε-25 and Tε + 85 is 1 MHz, the voltage is 1
Under the condition of V, the temperature of the porcelain capacitor is -25 ° C and +85
The change in the dielectric constant ε _r when the temperature was changed to ℃ was measured and determined according to the following formula. Tε-25 = {(εr20−εr-25) / εr20} / 45 Tε + 85 = {(εr20−εr + 85) / εr20} / 65 where εr20 is the relative permittivity at + 20 ° C, and εr -twenty five
Indicates the relative permittivity at −25 ° C., and εr + 85 indicates the relative permittivity at + 85 ° C.

[0015]

[Table 3]

[0016]

[Table 4]

Also in sample Nos. 2 to 43, the composition of the dielectric porcelain was changed as shown in Tables 1 and 2, and sample Nos.
Make a porcelain capacitor by the same method as in 1.
When ε _r , Q, Tε-25 and Tε + 85 were measured by the same method as in O.1, the results shown in Tables 3 and 4 were obtained.

Sample Nos. 1 to 17 and 24 to 3 in Tables 1 to 4
As is clear from 3, when the porcelain having the composition according to the present invention is used, the relative permittivity ε _r is 6.7 to 11.7 and the Q is 100.
0 to 1400, temperature coefficient of relative permittivity Tε-25, Tε + 85
It is possible to obtain a capacitor having a range of −60 ppm / ° C. to +60 ppm / ° C. On the other hand, sample Nos. 18 to 23 and 34 to 43 which do not belong to the composition range specified in the present invention cannot obtain desired characteristics. Therefore, these are comparative examples.

Next, the reasons for limiting the composition of the high frequency dielectric ceramics of the present invention will be described.

As shown in Sample No. 18, the molar ratio of BaO x
When the value is 0.01, it does not sinter at 900 ° C, but the sample N
As shown in O. 3 and 4, desired characteristics can be obtained when x is 0.02. Therefore, the lower limit of x is 0.02. 9 when x is 0.4 as shown in sample No. 19
Although not sintered at 00 ° C., desired properties can be obtained when x is 0.3 as shown in sample No. 6. Therefore, the upper limit of x is 0.3.

As shown in sample No. 20, when y indicating the molar ratio of TiO ₂ is 0.3, the temperature coefficient Tε of the relative dielectric constant is
-25 and Tε + 25 are out of the desired range, but sample No. 5
As shown in FIGS. 6 and 6, when y is 0.4, desired characteristics can be obtained. Therefore, the lower limit of y is 0.4. As shown in Sample No. 21, when y is 0.9, Tε-25,
Both Tε + 25 are out of the desired range, but as shown in sample Nos. 2 and 3, the desired characteristics are obtained when y is 0.85. Therefore, the upper limit of y is 0.85.

As shown in sample No. 22, Tε-25 and Tε + 25 when z, which represents the molar ratio of ReO _3/2 , is 0.03.
Is out of the desired range, but desired characteristics are obtained when z is 0.05 as shown in sample Nos. 1 and 2. Therefore, the lower limit of z is 0.05. When z is 0.52 as shown in sample No. 23, Tε-25 and Tε + 25 are out of the desired ranges, but when z is 0.5 as shown in sample Nos. 4 and 5. Gives the desired properties. Therefore, the upper limit of z is 0.5.

As shown in sample No. 42, when the main component is 15% by weight, Q is lower than a predetermined value, and Tε-25, T
Although ε + 25 is out of the predetermined range, desired characteristics can be obtained when the main component is 20% by weight as shown in sample No. 32. Therefore, the lower limit of the main component is 20% by weight. Sample N
As shown in O. 43, it is 90 when the main component is 74% by weight.
Although not sintered at 0 ° C., desired properties are obtained when the main component is 70% by weight as shown in sample No. 33. Therefore,
The upper limit of the main component is 70% by weight.

As shown in the sample No. 34, when the SiO ₂ is 5% by weight, the Q becomes lower than the desired value.
As shown in FIG. 4, when the SiO ₂ content is 10% by weight, desired characteristics are obtained. Therefore, the lower limit of SiO ₂ is 10% by weight. As shown in sample No. 35, when SiO ₂ is 60% by weight, it does not sinter at 900 ° C., but as shown in sample NO. 25, when SiO ₂ is 55% by weight, desired characteristics are obtained. . Therefore, the upper limit of SiO ₂ is 55% by weight.

As shown in Sample No. 36, CaO, SrO,
The total of Group 2 metal oxides consisting of BaO and ZnO is 0.5.
In the case of weight%, it is not sintered at 900 ° C, but sample No. 2
As shown in 6, when the total amount of the group 2 metal oxides is 1% by weight, desired characteristics can be obtained. Therefore, the lower limit of the above Group 2 metal oxide is 1% by weight. As shown in sample No. 37, when the total amount of the above group 2 metal oxides is 50% by weight, Q becomes smaller than the desired value, but as shown in sample NO. The desired properties are obtained when the total of the above is 40% by weight. Therefore, the upper limit of the Group 2 metal oxide is 40% by weight.

As shown in sample No. 38, when B ₂ O ₃ is 2% by weight, it does not sinter at 900 ° C., but as shown in sample NO. 28, when B ₂ O ₃ is 3% by weight. Gives the desired properties. Therefore, the lower limit of B ₂ O ₃ is 3% by weight. As shown in sample No. 29, when BO ₃ is 35% by weight, it is 9
It does not sinter at 00 ° C, but B ₂ O as shown in sample No. 29.
_{If 3} is 30% by weight, the desired properties are obtained. Therefore, the upper limit of B ₂ O ₃ is 30% by weight.

As shown in sample No. 40, Li ₂ O ₃ was less than 0.
In the case of 05% by weight, it does not sinter at 900 ° C,
When the Li ₂ O content is 0.1% by weight as shown in O. 30, desired characteristics are obtained. Therefore, the lower limit of Li ₂ O is 0.
It is 1% by weight. As shown in sample No. 41, Li ₂ O is 4
In the case of weight%, it is not sintered at 900 ° C, but sample No. 2
As shown in 9 and 31, the desired characteristics are obtained when Li ₂ O is 3% by weight. Therefore, the upper limit of Li ₂ O is 3% by weight.

[0028]

[Second Embodiment] Sample Nos. 1 to 17 of the first embodiment and dielectric ceramics having the same composition as 24-33 are used in FIG.
A plurality of types of high frequency laminated ceramic capacitors 18 shown in FIG. The multilayer ceramic capacitor 18 of FIG. 2 includes a dielectric ceramic substrate 20, first and second internal electrodes 22 and 24, and first and second external electrodes 26 and 28 to which these are connected. In this example, a green sheet (unfired porcelain sheet) of a porcelain material having a composition according to the present invention was prepared, silver paste for obtaining the internal electrodes 22 and 24 was applied thereto, these were laminated, and the top and bottom were laminated. A cover sheet (green sheet) having no electrode layer is placed on the sheet, and the sheets are pressure-bonded and then cut to obtain a desired molded body.
It was fired at 00 ° C. to obtain a porcelain substrate 20, and silver paste was applied to both sides of the porcelain substrate 20 and baked to complete a porcelain capacitor. Also in the laminated ceramic capacitor thus configured, the same characteristics as those of the first embodiment were obtained.

[0029]

MODIFICATION The present invention is not limited to the above-mentioned embodiments, and the following modifications are possible. (1) BaO, TiO ₂ , R which are the components of the dielectric ceramics
eO _3/2 , CaO, SrO, BaO, ZnO, B
Starting materials for obtaining ₂ O ₃ and Li ₂ O can be variously selected from oxides, hydroxides, carbonates, elements and the like. Further, SiO ₂ can also use a compound or element other than this as a starting material. (2) The firing temperature of the porcelain can be selected from the range of 800 to 1400 ° C, for example. (3) The porcelain of the present invention can also be used for the dielectric resonator and the dielectric block of the dielectric filter.

[Brief description of drawings]

FIG. 1 is a front view showing a porcelain capacitor of a first embodiment.

FIG. 2 is a sectional view showing a laminated ceramic capacitor of a second embodiment.

[Explanation of symbols]

 12 porcelain substrate 14, 16 electrodes

─────────────────────────────────────────────────── ───

[Procedure amendment]

[Submission date] July 12, 1993

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] Claim 1

[Correction method] Change

[Correction content]

[Procedure Amendment 2]

[Document name to be amended] Statement

[Name of item to be corrected] 0005

[Correction method] Change

[Correction content]

[0005]

The present invention for achieving the above-mentioned object is xBaO + yTiO ₂ + zReO _3/2 where x, y and z are 0.02 ≦ x ≦ 0.3 and 0.4 ≦ y
≦ 0.85, 0.05 ≦ z ≦ 0.5, numerical values satisfying x + y + z = 1, Re is La, Pr, Nd, Sm, Gd,
20 to 70% by weight of a main component consisting of one or more rare earth elements selected from Dy, Er and Yb, and 10 to 55
Wt% SiO ₂ , 1-40 wt% CaO, Sr
One or more Group 2 metal oxides selected from O, BaO and ZnO, 3 to 30 wt% B ₂ O ₃ and 0.1 to 3.
It relates to a dielectric ceramic composition containing 0% by weight of Li ₂ O.

[Procedure 3]

[Document name to be amended] Statement

[Correction target item name] 0020

[Correction method] Change

[Correction content]

As shown in Sample No. 18, the molar ratio of BaO x
When the value is 0.01, it does not sinter at 900 ° C, but the sample N
As shown in O. 3 and 4, desired characteristics can be obtained when x is 0.02. Therefore, the lower limit of x is 0.02. 9 when x is 0.4 as shown in sample No. 19
Although not sintered at 00 ° C., desired properties can be obtained when x is 0.3 as shown in sample No. 6. Therefore, the upper limit of x is 0.3.

[Procedure amendment 4]

[Document name to be amended] Statement

[Correction target item name] 0021

[Correction method] Change

[Correction content]

As shown in sample No. 20, when y indicating the molar ratio of TiO ₂ is 0.3, the temperature coefficient Tε of the relative dielectric constant is
-25, Tε +85 is out of the desired range, but sample No. 5
As shown in FIGS. 6 and 6, when y is 0.4, desired characteristics can be obtained. Therefore, the lower limit of y is 0.4. As shown in Sample No. 21, when y is 0.9, Tε-25,
Both Tε + 25 are out of the desired range, but as shown in sample Nos. 2 and 3, the desired characteristics are obtained when y is 0.85. Therefore, the upper limit of y is 0.85.

[Procedure Amendment 5]

[Document name to be amended] Statement

[Name of item to be corrected] 0022

[Correction method] Change

[Correction content]

As shown in Sample No. 22, Tε -25 and Tε +85 when z, which represents the molar ratio of ReO _3/2 , is 0.03.
Is out of the desired range, but desired characteristics are obtained when z is 0.05 as shown in sample Nos. 1 and 2. Therefore, the lower limit of z is 0.05. When z is 0.52 as shown in sample No. 23, Tε -25 and Tε +85 are out of the desired ranges, but when z is 0.5 as shown in sample Nos. 4 and 5. Gives the desired properties. Therefore, the upper limit of z is 0.5.

[Procedure correction 6]

[Document name to be amended] Statement

[Name of item to be corrected] 0023

[Correction method] Change

[Correction content]

As shown in sample No. 42, when the main component is 15% by weight, Q is lower than a predetermined value, and Tε-25, T
Although ε +85 deviates from the predetermined range, desired characteristics can be obtained when the main component is 20% by weight as shown in sample No. 32. Therefore, the lower limit of the main component is 20% by weight. Sample N
As shown in O. 43, it is 90 when the main component is 74% by weight.
Although not sintered at 0 ° C., desired properties are obtained when the main component is 70% by weight as shown in sample No. 33. Therefore,
The upper limit of the main component is 70% by weight.

[Procedure Amendment 7]

[Document name to be amended] Statement

[Correction target item name] 0026

[Correction method] Change

[Correction content]

As shown in sample No. 38, when B ₂ O ₃ is 2% by weight, it does not sinter at 900 ° C., but as shown in sample NO. 28, when B ₂ O ₃ is 3% by weight. Gives the desired properties. Therefore, the lower limit of B ₂ O ₃ is 3% by weight. Sample NO. 29 B ₂ O ₃ as shown in, but are not sintered at 900 ° C. in the case of 35 wt%, the sample NO. As shown in 29 B ₂
The desired properties are obtained when O ₃ is 30% by weight. Therefore, the upper limit of B ₂ O ₃ is 30% by weight.

[Procedure Amendment 8]

[Document name to be amended] Statement

[Name of item to be corrected] 0027

[Correction method] Change

[Correction content]

As shown in sample No. 40, Li ₂ O was 0.0
In the case of 5% by weight, it does not sinter at 900 ° C, but sample NO.
As shown in 30, when Li ₂ O is 0.1% by weight, desired characteristics are obtained. Therefore, the lower limit of Li ₂ O is 0.1% by weight. When Li ₂ O is 4% by weight as shown in sample NO. 41, it does not sinter at 900 ° C., but as shown in samples NO. 29 and 31, when Li ₂ O is 3% by weight, it is desired. The characteristics are obtained. Therefore, the upper limit of Li ₂ O is 3% by weight.

Claims (1)

[Claims] 1. xBaO + yTiO ₂ + zReO _3/2 where x, y and z are 0.02 ≦ x ≦ 0.3 0.4 ≦ y ≦ 0.85 0.05 ≦ z ≦ 0.5 x + y + z = 1 Satisfying numerical value, Re is La, Pr, Nd, Sm, Gd, Dy, Er, Y
20 consisting of one or more rare earth elements selected from b
70% by weight of the main component, and SiO ₂ of 10 to 55 wt%, 40 wt% of CaO, SrO, BaO, and Group 2 metal oxide selected from ZnO, 3 to 30 wt% of B A dielectric ceramic composition containing ₂ O ₃ and 0.1 to 3.0% by weight of Li ₂ O.