JPH02242525A - Dielectric porcelain composition - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] To Industrial Application Field 3-7 The present invention has high dielectric constant, insulation resistance, and dielectric breakdown voltage, excellent quality QK, and small capacitance temperature coefficient, and is suitable for use in multilayer ceramic capacitors. This invention relates to a dielectric ceramic composition that can prevent a decrease in capacitance and quality Q when the thickness of an internal electrode is reduced, and can reduce variations in capacitance and quality Q.

Conventional technology Conventionally, the dielectric constant and insulation resistance are high, and the quality Q is excellent.
The following systems are known as dielectric ceramic compositions with small capacitance temperature coefficients.

-Ba0-TiO2-Nd203 system -BaO-Ti02- Sm203 system Problems to be solved by the invention However, these compositions, for example, 0.11 BuOO, 6
Using a dielectric material with a composition ratio of 8TiO2-0, 21Nd203, the internal electrode thickness of palladium was 4/Zm,
Dielectric thickness 1271m, geo method with overlapping internal electrodes 1.2m
+nX0. When a multilayer ceramic capacitor with a laminated structure of γ groups and 19 dielectric layers is manufactured, the average value of capacitance is 42 pF, the average value of quality Q is 28,700, and the average value of capacitance temperature coefficient is NN35 pp/'C. .

Average value of insulation resistance: 6. OX 1012Ω, average value of dielectric breakdown strength: 117 KV/, which is a satisfactory value in terms of insulation resistance and dielectric breakdown strength.

In addition, in order to perform cost I-town of the multilayer ceramic capacitor and to prevent the occurrence of delamination, which is a structural defect inside the element body, the thickness of the palladium internal electrode was increased to 4 μm.
When thinning from m to 2 μm, a dielectric thinning material with the above composition ratio is used, the dielectric thickness is the above, the internal electrode thickness is reduced,
The average value of capacitance of a multilayer ceramic capacitor having a laminated structure with a number of dielectric layers is as small as 610 pF, and the variation in capacitance is large as 256 to 713 pF. Furthermore, there was a problem in that the average value of the quality level Q was as low as 4,000, and the variation in the quality level Q was large, ranging from 6° to 8,800.

Means to solve problems In order to solve these problems, the present invention develops the general formula %formula% When expressed as (however, X+7+Z=1.O○.

ReObaLa2O3, Pr201. /3. Nd2O
An oxide of at least one rare earth element selected from 3, Sm, and 03. ), x+ V r z represents each point color below.

0.3 to 8.0 parts by weight of niobium oxide, calculated as Nb2O5, was contained as a subcomponent to 100 parts by weight of the main component having a molar ratio range surrounded by b, c, d, e, and f. This paper proposes a dielectric ceramic composition characterized by the following.

t1 Effect FIG. 1 is a ternary diagram showing the composition range of the main components of the composition according to the present invention.The reason for limiting the composition range of the main components will be explained with reference to FIG. That is, sintering is extremely difficult in the human region. That's naive. In area B, the quality Q decreases and it becomes impractical. Furthermore, in regions C and D, the temperature coefficient becomes too steep on the negative side, making it impractical.

In region E, the capacitance temperature coefficient shifts to a positive direction, but the dielectric constant is too small to be practical. Also, Re20
゜f La205. Pr20. , /3. Nd2O3
, Sm2O3, lI: ri, La, , 0
5. Pr20. , /3. Nd2O3, Sm203(
7) It is possible to shift the temperature coefficient to the positive direction without significantly lowering the dielectric constant, and La2O3゜Pr
2011/3. The capacity temperature coefficient can be adjusted by using one or a combination of Nd2o6 and 5m2o5.

FIG. 2 is a graph showing the effect of the inclusion of the subcomponent Nb2O5 on the characteristics of a multilayer ceramic capacitor with respect to the main component of the composition according to the present invention, and the reason for limiting the content range of Nb2O5 will be explained with reference to the graph. △ Yes. As shown in FIG. 2, the inclusion of Nb2O5 has the effect of improving insulation resistance, dielectric breakdown strength, and quality Q, increasing the capacitance caused by the capacitance, and reducing variations in the capacitance. Due to the inclusion of Nb2O5, insulation resistance,
The dielectric breakdown strength improves, but if the content of Nb2O5 is less than 0.3 parts by weight based on 100 parts by weight of the main component, the dielectric breakdown strength is not so great, the capacitance and goodness Q are low, and the capacitance Since the variation in quality Q was large, it was excluded from the scope of this invention. On the other hand, if the content of Nb2o5 exceeds 8.0 parts by weight based on the main component, the quality Q and insulation resistance will decrease, the temperature coefficient of capacitance will become thicker on the negative side, and the temperature coefficient of capacitance will change linearly. It loses its character and becomes impractical.

The present invention further provides the above composition with at least one selected from oxides of manganese, zinc, iron, and silicon.
It can be configured such that 0.05 to 1.00 parts by weight are added to 100 parts by weight of the main component and subcomponent in terms of MnO2, ZnO, Fe2O3 and SiO2, respectively. These additives have the effect of improving the sinterability of porcelain, but if the amount added is less than 0.05 parts by weight, there is no effect, and if it exceeds 1.00 parts by weight, the dielectric constant decreases and it is not practical. It disappears.

Example The present invention will be explained below using specific examples.

(Example 1) Starting materials include chemically high-purity BaCO2, TiO2°La205. Pr60.1. N4205. Sm2
05 and Nb2O5 powders were weighed so as to have the composition ratios shown in Table 1 below, and put into a ball mill with a rubber-lined jig equipped with agate balls together with pure water, and after wet mixing, they were dehydrated and dried. This dry powder was placed in a high alumina crucible and calcined in air at 1100°C for 2 hours. This calcined powder was placed together with pure water in a rubber-lined Polmill equipped with an agate ball, wet-pulverized, and then dehydrated and dried. An organic binder was added to this pulverized powder to make it homogeneous, and then the granules were sized through a 32-mesh sieve, and molded using a mold and hydraulic press at a molding pressure of 1 ton/i to a diameter of 15 pieces and a thickness of about 0.4 mm. .

9,,-,.

Next, this molded disk was placed in an alumina sheath covered with zirconia powder and fired in air at the temperature shown in Table 1 for 2 hours to obtain dielectric porcelain having the composition ratio shown in Table 1.

The element thickness and diameter of the dielectric ceramic disk obtained in this way were measured, and the sample for measuring the dielectric constant, goodness Q, and capacitance temperature coefficient was prepared by baking silver electrodes on the entire both sides of the dielectric ceramic disk. , insulation resistance, and dielectric breakdown strength measurements were prepared by providing a portion without a silver electrode at 19/1] inside the outer periphery of a dielectric ceramic disk, and baking the silver electrode. Then, the dielectric constant, goodness Q,
The temperature coefficient was measured using YHP digital LCFL meter model 4276A, measuring temperature 20°C, measuring voltage 1, ○
Vrms was determined by measurement at a measurement frequency of 1 MHz. Note that the temperature change in capacitance is -65°C.

The capacitance was measured at -26°C, 20'C, 86°C, and 125°C, and the linearity was confirmed, and the capacitance temperature coefficient was 2.
It was calculated using the following formula using capacitances at 0°C and 86°C.

Go to 10 capacitance at co=20℃ (pF) C,:a Capacitance at 6℃ (pF') In addition, the dielectric constant was determined using the following formula.

Dielectric constant -°°3°axe・xo・Co: Capacitance at 20°C (pF) D: Diameter of dielectric porcelain (size) t: Thickness of dielectric porcelain (tone) Furthermore, the insulation resistance is , YHP HR meter model 4
329A, measuring voltage 60V, D, C,.

It was determined by measurement with a measurement time of 1 minute.

The dielectric breakdown strength was determined by using a type 13 voltage power supply PH836 manufactured by Kikusui Electronics Co., Ltd., placing the sample in silicone oil, and calculating the dielectric breakdown voltage using the boost rate sob/sea. Divided by the thickness, the dielectric breakdown strength was determined to be 1/9.

Test conditions and results are also shown in Table 1.

13 ・＼−・ (Example 2) Chemically high purity BaCO3, TiO2゜L2L203. Pr6O11. Nd205. Sm203
1NSm2O31Nb2051, Fe2O3 and S
The powder was weighed to have the composition ratio shown in Table 2 below, and then treated in the same manner as in Example 1 to obtain dielectric porcelain having the composition ratio shown in Table 2. .

The test methods for these samples were the same as in Example 1, and the test conditions and results are also shown in Table 2.

(Hereinafter referred to as gold and white) Go to 16 (Example 3) Chemically high-purity BaCO3, TiO2゜Nd2O5, Sm2O3 and Nb2O5 powders were used as starting materials, and the main components were 0.11BaO-0,68TiO2-0,2.
Nb205i 0 , 0.1 for 1Nd2O3
, 0.3, 0.5, 1.0.

6.0, 8.0, 10. A calcined and pulverized powder containing Owt% is prepared in the same manner as in Example 1. However, Nb2O
5 content 0, 0.1.10. Owt% is outside the scope of this invention and is 0.3, 0.5, 1.0, 5. ○、s
, owt% is within the scope of this invention.

Calcined and ground powder with organic binder and plasticizer.

A dispersant and an organic solvent were added and mixed in a polyethylene pot equipped with an alumina ball to prepare a slurry. After mixing, the mixture was thoroughly filtered using a 300 mesh nylon cloth.

The slurry from Sawadori was molded using a doctor blade onto a polyester film that had been subjected to mold release treatment so that the dielectric thickness after sintering was approximately 12 μm. Next, 10 sheets peeled from the polyester film were laminated on a support base. On top of this, ML-3724 (electrode palladium base, manufactured by Shoei Kagaku Co., Ltd.) was screen printed so that the internal electrode thickness after sintering would be 2 μm, and then dried. A sheet peeled from a polyester film was laminated on top of this. On top of this, internal electrode palladium paste was printed by shifting the printing position so that the internal electrode overlap dimensions after sintering were approximately 1.2 mm x approximately 0.7 gates, and after drying, one sheet was peeled off from the polyester film. Laminated. These operations were repeated until the number of dielectric layers was 19.

On top of this, add 10 pieces of paper peeled from the polyester film.
The sheets were stacked. After sintering this laminate, the internal electrode overlap dimensions are approximately 1.2 m x approximately 0.7 m, and the dielectric thickness is approximately 127 m.
The capacitor was cut into a multilayer ceramic capacitor having a multilayer structure with zm and 19 dielectric layers. This cut sample was placed in an alumina pod covered with zirconia powder.
In air, from room temperature to 350'C, 5°C/h
The temperature was raised at 360°C and 100°C/hr.
After baking at 270°C for 2 hours, the temperature was lowered to room temperature at 100°C/hr.

Then, the sample after sintering was coated with water-resistant sand vapor 1 7
1.-7 Put it in a polyethylene pot with pure water attached to the inside,
The polyethylene pot was rotated to polish the surface of the sintered sample to fully expose the internal electrode portion that would be connected to the external electrode.

Next, the sample was taken out of the polyethylene pot and dried, and then a silver external electrode was baked onto the exposed part of the internal electrode to make it electrically conductive with the internal electrode, thereby completing the entire multilayer ceramic capacitor.

The capacitance, quality Q, temperature coefficient of capacitance, insulation resistance, and dielectric breakdown strength of these samples were determined by measurement under the same conditions as in Example 1. In addition, to confirm the laminated structure, a polished cross section of about 1/2 in the length and width directions of the laminated ceramic capacitor was examined, and the dimensions of the internal electrodes were measured at a magnification of 100. The dielectric thickness and the internal electrode thickness were determined by observation at a magnification of 400.

The measurement results are shown in FIG.

In addition, in the method for manufacturing dielectric ceramic in the example, BaC
O3, TiO2, La2O3, Pr60. , , N
d2O3°Sm, 03. Nb2O5, MnO2, Z
Although nO, Fe2O2, and 5102 were used, the method is not limited to this method, and 18 to -7 compounds such as B a T 103, or carbonates, hydroxides, etc., may be used to obtain the desired composition ratio. By heating in the Ba0ITi02. La2o5. Pr6O11
°Nd2O3, Sm2o51Nb205. MnO□1Z
Characteristics comparable to those of the examples can be obtained even when compounds forming nO9Fe203 and SiO2 are used. Further, even if the main component is calcined in advance and the subcomponents are added, properties comparable to those of the examples can be obtained.

1. Titanium oxide, an industrial raw material commonly used for electric porcelain, such as titanium oxide K manufactured by Titan Kogyo Co., Ltd.
A-10. Furukawa Mining Co., Ltd. Membrane titanium oxide FA-56W contains up to 0.46% by weight of Nb2O5, but even if these titanium oxides are used to create dielectric ceramics as the main component, only 100 parts by weight of the main component. On the other hand, the maximum content of Nb2O5 is 0.23 parts by weight, which is outside the scope of this invention, but considering the amount of Nb2O5 in titanium oxide, which is an industrial raw material, it is possible to contain all the Wb205 that is insufficient. Accordingly, characteristics comparable to those of the example can be obtained.

Effects of the Invention As described above, according to the present invention, the dielectric constant, insulation resistance 19/
, has high dielectric breakdown voltage, excellent dust Q, and small temperature coefficient of capacitance, and when used in multilayer ceramic capacitors, reduces capacitance and dust Q when thinner internal electrodes are used. Since the variation in capacitance and good dust Q can be reduced, the thickness of the internal electrodes can be reduced to reduce the cost of multilayer ceramic capacitors, and the occurrence of delamination, which is an internal structural defect, can be prevented. Since the dielectric breakdown voltage is high, it is possible to reduce the thickness of the dielectric layer and make the element smaller and increase the capacity.

Furthermore, the addition of oxides of manganese, zinc, iron and silicon allows the firing temperature to be lowered.

[Brief explanation of drawings]

FIG. 1 is a ternary diagram explaining the composition range of the main components according to the present invention, and FIG. 2 is a ternary diagram explaining the composition range of the main components according to the present invention.
o, 6s TiO2-0,21Nd203VC vs.-f
dielectric thickness: 12 μm
. This is a graph showing the electrical characteristics of a multilayer ceramic capacitor having a multilayer structure of internal electrode type dimensions: 1.2 mm x 0.7 m + 219 dielectric layers.

Claims (2)

[Claims] (1) When expressed as the general formula xBaO-yTiO_2-zRe_2O_3 (where x+y+z=1.00. Re_2O_3 is La_2O_3, Pr_2O_1_
An oxide of at least one rare earth element selected from 1_/_3, Nd_2O_3, and Sm_2O_3. ), x
, y, z are in the range of molar ratios surrounded by points a, b, c, d, e, f shown below, and niobium oxide is added as a subcomponent in terms of Nb_2O_5. A dielectric ceramic composition characterized in that it contains 0.3 to 8.0 parts by weight. ▲Contains mathematical formulas, chemical formulas, tables, etc.▼ (2) For 100 parts by weight of the main component and subcomponents combined, at least one selected from oxides of manganese, zinc, iron, and silicon are added to MnO_2, ZnO, and
0.05 to 1 in terms of Fe_2O_3 and SiO_2
．． 2. The dielectric ceramic composition according to claim 1, wherein 00 parts by weight are added.