JPS61251561A - Dielectric ceramic composition and manufacture - 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 (Field of Industrial Application) The present invention relates to a dielectric ceramic composition based on barium titanate suitable for use in capacitors, and a method for producing the same.

(Prior art) Conventionally, barium titanate and compositions containing barium titanate and shifters, depressors, etc.
It is sintered at a high temperature of 0 to 1400°C and is used as a capacitor. However, sintering at such high temperatures causes wear and tear on the expensive zirconia center and sintering furnace, and requires a large amount of energy for sintering, making the resulting capacitors expensive. Become.

Furthermore, in order to manufacture multilayer capacitors using conventional compositions, it is necessary to use expensive noble metals such as platinum and palladium that can withstand high sintering temperatures as internal electrode materials. Multilayer capacitors are significantly more expensive.

Therefore, the dielectric composition can be sintered at low temperatures, which reduces wear and tear on the center and sintering furnace, and allows the use of inexpensive silver-based internal electrodes when manufacturing multilayer capacitors. Something is strongly desired.

Copper oxide is known as one of the sintering aids that can lower the sintering temperature of barium titanate. By adding 0.5 mol% or less of cupric oxide to barium titanate, 1
Trans, Br1t that a sintered body having approximately the theoretical density can be obtained at a sintering temperature of 200°C.

Cerata, Soc, 74.165. (1
975).

In JP-A-53-8200, Cu is added to propeskite oxide.
O-CuzOgMfi,,*fs! J: CuO-
C8zO1Me”O.

Adding a compound that forms a eutectic mixture (where Me■0□ is at least one oxide selected from group ■ elements that is not incorporated into the propeskite lattice),
A method for manufacturing a dielectric is disclosed, which is characterized by sintering at a temperature in the range of 0 to 1200°C.

However, the dielectric porcelain obtained by these methods has a large and non-uniform dalein size, and in some cases has a diameter of several 1
Since giant particles as large as 0μ are generated, the characteristics are unstable, and in fact, it cannot be used particularly in multilayer capacitors.

On the other hand, JP-A No. 54-53300 discloses that CuO-MeO)+ (where MeO* is at least one oxide of groups ■, V, VI, and ■ of the periodic table) for propelskite oxide. and not incorporated into the propeskite lattice) by adding an oxide forming a eutectic mixture, and 1
A method for manufacturing dielectric ceramic is disclosed, which is characterized by sintering at a temperature in the range of 000 to 1250°C. Although this method yields a uniform sintered body with relatively small dalein, it has drawbacks such as large dielectric loss and low insulation resistance in practice, and also has a low dielectric constant of about 1,700 to 3,200.

Furthermore, thallium, which exhibits the best properties, is highly toxic and expensive, which poses a major problem in practice.

(Problems to be Solved by the Invention) Therefore, in the prior art, it is possible to sinter at a temperature of 1200°C or less, have a high dielectric constant, have a high insulation resistance, have a small dielectric loss, and have a uniform dielectric material with minute dalein. The body porcelain composition is unknown.

(Means for Solving the Problems) As a result of various studies, the present inventors have found that barium titanate is combined with specific amounts of copper oxide, zinc oxide, and/or cadmium oxide, thereby eliminating the above-mentioned drawbacks. The present invention was achieved by discovering that a dielectric material can be obtained.

That is, in the present invention, the first component is 87.5 to 99.
6 mol% barium titanate, 0.2~ as second component
A dielectric ceramic composition consisting of 5.5 mol% zinc oxide and/or oxidizing power Fmium, 0.2 to 7.0 mol% copper oxide as the third component, and 87.5 mol% as the first component.
~99.6 mol% barium titanate, 0.2-5.5 mol% zinc oxide and/or cadmium oxide as second component, 0.2-7.0 mol% copper oxide as third component The present invention relates to a method for producing a dielectric ceramic composition by sintering a mixture at a temperature of 1000 to 1200°C.

Barium titanate with specific amounts of steel oxide and zinc oxide and/or
or a mixture of cadmium oxide, 100
By sintering at a temperature of 0 to 1200° C., a dielectric ceramic composition with a smaller tan δ value, smaller and more uniform dalein size, and higher insulation resistance than copper oxide alone can be obtained. If the sintering temperature is less than 1000°C, it is difficult to obtain dense porcelain, and if it exceeds 1200°C, grain growth tends to occur, the dalein size tends to increase, and the tan
The value of δ also shows a tendency to increase. Furthermore, zinc oxide is more effective than cadmium oxide in exhibiting these properties.

Furthermore, by combining a specific amount of one or more selected from specific titanate, zirconate, and stannate as the fourth component, the value of the dielectric constant near room temperature can be increased to 10% without impairing the above characteristics. It is possible to change the diameter to .000 or more, and it is also possible to further reduce the duplex size.

The barium titanate used in the present invention may be produced by any method such as a solid phase method, a liquid phase method, an oxalate method, or an alkoxide method. When using particles with a small average grain size of 1μ or less and a uniform grain size distribution, a porcelain with a more uniform microstructure can be obtained, the insulation resistance value will be large, and the variations in various properties will be small. .

In the present invention, oxides can be used as they are as zinc oxide, cadmium oxide, and copper oxide, but inorganic acid salts such as hydroxides and carbonates, and organic salts such as oxalates 1 and alkoxides can also be used. Any material that decomposes to form an oxide below the freezing temperature can be used. As the copper oxide, any of monovalent copper oxides, divalent copper oxides, and monovalent and divalent copper oxides can be used.

Further, in the present invention, lead titanate, strontium titanate, barium zirconate, calcium zirconate, strontium zirconate, lead stannate, calcium stannate,
Strontium stannate and barium stannate are each Pb
Ti0. ．． 5rTiOs, BaZrOs, CaZr
O3,5rZrO,, Pb5nOs, CaSnO3,5
Commonly used composite oxides such as rSnOz and Ba5nOs are preferably used.

The proportion of barium titanate in the porcelain composition of the present invention is 8
The range is from 7.5 to 99.6 mol%. The percentage is 99
．． If it is more than 6 mol %, sintering becomes difficult at temperatures below 1200° C., and if it is less than 87.5 mol %, significant deformation of the base material occurs during sintering. The preferable range is 92.5 to 92.5 for good sinterability and almost no deformation of the base material.
It is 99.4 mol%.

The proportion of zinc oxide and/or cadmium oxide is 0.2 to 5.5 mol% in total as ZnO and CdO type, respectively.
is within the range of If it exceeds 5.5 mol %, sintering is difficult at low temperatures of 1200° C. or lower, and the insulation resistance value is also small. If the amount is less than 0.2 mol %, almost no effect will be observed. The most preferable range for providing good sinterability and sufficiently high insulation resistance is 0.3 to 3.5 mol%.

The proportion of copper oxide is in the range of 0.2 to 7.0 mol% as CuO. When the amount is more than 7.0 mol %, the deformation of the substrate becomes significant and the value of dielectric loss becomes large. In addition, the size of the sinterable dalein is non-uniform and becomes large.

If it is less than 0.2 mol%, low temperature sintering becomes difficult. The preferable range is 0.3 to 3.5 mol %, in which the sintered body has a uniform dalein size, almost no deformation of the base material, and extremely small dielectric loss.

Further, the best results with good insulation resistance and low dielectric loss are obtained when the molar ratio of zinc oxide and/or cadmium oxide to copper oxide is 1:3 to 3:1.

Furthermore, in a preferred embodiment, one or more selected from lead titanate, strontium titanate, barium zirconate, calcium zirconate, strontium zirconate, lead stannate, calcium stannate, strontium stannate, and barium stannate. The composite oxide is the first component and the second component.
2.5 to 40% per 100 moles of the total of the components and the third component.
It is added in an amount of 0 mol, more preferably 5.0 to 25.0 mol. When the amount is less than 2.5 mol, the effect of addition is not so pronounced, the grain size does not decrease, and furthermore,
The dielectric constant value is not too large (not too large. Even if it exceeds 40.0 mol, the dielectric constant value tends to be small and the insulation resistance value tends to be small. 5.0 to 25.0 mol%)
A particularly high dielectric constant can be obtained within the range of . When barium stannate, calcium stannate, or a mixture thereof is used, a material with a large dielectric constant can be easily obtained.

(Example) Hereinafter, the present invention will be explained in detail with reference to Examples.

Example 1 Barium titanate, zinc oxide, cadmium oxide, and copper oxide were weighed in the proportions shown in Table 1, pure water was added, and they were mixed using a nylon pot and a nylon ball.

After drying the mixture, an appropriate amount of polyvinyl alcohol was added as a binder, and after granulation and drying, a disc-shaped molded product with a diameter of 15 mm and a thickness of 0.6 mm was created under a pressure of 2t7ci. Next, stack 5 of these on the zirconia center,
Sintering was performed under the sintering conditions shown in Table 1.

Silver electrodes of 10 ma+φ were baked on both sides of the obtained disc porcelain, and various characteristics were measured. Dielectric constant and dielectric loss (tanδ
) using an LCR meter, IKHz.

It was measured under the conditions of 1V and 20°C. The insulation resistance value was measured using a high insulation resistance needle and applying a voltage of 500V.

In addition, a scanning electron micrograph of the porcelain surface was taken to determine the grain size. The sintered density was determined by dividing the weight of the disc by the volume measured using a micrometer. The measurement results are shown in Table 2. Sample 11m1.4.6.7 is outside the scope of the present invention, and samples 2 and 3.5 are within the scope of the present invention. As is clear from Table 2, those within the scope of the present invention have a small tan δ, a high insulation resistance, a large sintered body density, and a small grain size.

Table 1 Table 2 [- Example 2 Barium stannate and calcium stannate were used as the fourth component. Various compounds were weighed in the proportions shown in Table 3, and disk-shaped molded products were prepared in the same manner as in Example 1, and sintered under the sintering conditions shown in Table 3. A silver electrode was baked in the same manner as in Example 1, and various characteristics were measured. From scanning electron micrographs of the porcelain surface, the average dalein size was determined using the line intercept method. The measurement results are shown in Table 4. Sample No. 2.4 is outside the scope of the present invention, and samples Na7 and 9 have amounts of the fourth component that are outside the scope of the preferred embodiment of the present invention. As is clear from Table 4, by adding barium stannate and calcium stannate, the dielectric constant at 20°C can be reduced to 1 while keeping tan δ small and insulation resistance high.
It can be seen that the diameter can be increased to 0.000 or more, and the dalein size can also be reduced.

The amounts of barium stannate and calcium stannate are shown inside.

Table 3 Table 4”! Example 3 The composition shown in Table 5 was weighed, alcohol was added, and the mixture was mixed in a 1-iron ball mill. The resulting mixture was dried for 10 minutes.
Pass it through a 0 mesh sieve, add a binder to the acrylic wood,
Using trichloroethane as a solvent, a paste was prepared using a Shinou Ball ball mill. Using the obtained paste, a disk having a diameter of 12 mm and a cutting speed of 0.4 tam was prepared and sintered using the sintering strips shown in Table 5. A silver electrode with a diameter of 81 mm was baked and its characteristics were measured in the same manner as in Example A2. The results are shown in Table 6. It can be seen that in this example as well, a dielectric layer with good characteristics was obtained.

Table 5 Table 6 In the above examples, barium titanate contains Ba and Ti.
Although a material having a molar ratio of approximately 1 was used, good characteristics can be obtained even if the ratio deviates by about 0.05 mole. Further, when a trace amount of aluminum oxide, silicon dioxide, etc. is added to the composition of the present invention, it is effective in improving the characteristics.

(Effects of the Invention) From the above, the dielectric ceramic composition of the present invention has 1
It can be sintered at a low temperature of 200° C. or lower, has a small tan δ, a uniform and small duplex size, and has a large insulation resistance. In addition, the dielectric constant near room temperature can be increased to 10.000 or more without impairing these properties.
It is extremely effective as a ceramic composition for multilayer ceramic chip capacitors, and has great industrial value.

Claims (11)

[Claims] (1) 87.5-99.6 mol% barium titanate as the first component, 0.2-5.5 mol% zinc oxide and/or cadmium oxide as the second component, 0.2 as the third component A dielectric ceramic composition comprising ~7.0 mol% of copper oxide. (2) Claims in which the first component is 92.5 to 99.4 mol%, the second component is 0.3 to 3.5 mol%, and the third component is 0.3 to 4.0 mol%. 2. The dielectric ceramic composition according to item 1. (3) The dielectric ceramic composition according to claim 1 or 2, wherein the molar ratio of the second component to the third component is 1:3 to 3:1. (4) The dielectric ceramic composition according to any one of claims 1 to 3, wherein the second component is zinc oxide. (5) 87.5-99.6 mol% barium titanate as the first component, 0.2-5.5 mol% zinc oxide and/or cadmium oxide as the second component, 0.2 as the third component The composition consists of ~7.0 mol% copper oxide, and the fourth component is lead titanate, strontium titanate, barium zirconate, calcium zirconate, strontium zirconate, lead stannate, calcium stannate, and strontium stannate. A dielectric ceramic composition containing 2.5 to 40.0 moles of one or more selected from barium stannate, based on 100 moles of the sum of the first, second, and third components. (6) The dielectric ceramic composition according to claim 5, wherein the fourth component is 5.0 to 25.0 moles. (7) The dielectric ceramic composition according to claim 5 or 6, wherein the fourth component is barium stannate and/or calcium stannate. (8) 87.5-99.6 mol% barium titanate as the first component, 0.2-5.5 mol% zinc oxide and/or cadmium oxide as the second component, 0.2 as the third component 10 of a mixture consisting of ~7.0 mol% copper oxide
87.5 to 99.6 mol% barium titanate as the first component, 0.2 to 5.5 mol% zinc oxide as the second component, characterized by being sintered at a temperature of 00 to 1200 ° C. / or cadmium oxide, 0.2 as third component
A method for producing a dielectric ceramic composition comprising ~7.0 mol% copper oxide. (9) the first component of the mixture is 92.5 to 99.4 mol%;
The second component is 0.3 to 3.5 mol%, and the third component is 0.3 to 3.5 mol%.
The manufacturing method according to claim 8, wherein the content is 4.0 mol%. (10) The molar ratio of the second component and the third component of the mixture is 1:3
The manufacturing method according to claim 8 or 9, wherein the ratio is 3:1. (11) The method according to any one of claims 8 to 10, wherein the second component of the mixture is zinc oxide.