JPH01201070A - Dielectric ceramic 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 (Field of Industrial Application) The present invention relates to a dielectric ceramic composition containing barium titanate as a main component. The present invention relates to an electrically conductive composition.

(Conventional Techniques Conventionally, the sintering temperature of strong electromagnetic ceramic compositions containing barium titanate as the main component is extremely high, at 1300C or higher, so when used for multilayer capacitors, high-temperature sintering is required as an internal electrode material. High-melting point noble metals 1 that can withstand freezing temperatures, such as platinum, palladium, and gold, have been used.

Since these precious metals are expensive, the cost of the multilayer capacitor is also high. However, issues such as sintering at high temperatures, the design of the sintering furnace, and the energy required for sintering also arise. In other words, when manufacturing a multilayer capacitor, it is preferable to use inexpensive silver as the main component for the internal electrode material from the viewpoint of cost, and it is also preferable to use silver as the main component as the internal electrode material, and also to simplify the furnace design. A possible ferroelectric ceramic composition is highly desirable.

As a sintering aid to lower the sintering temperature of barium titanate, copper arsenate [Trans, Br1t, Cera
m.

SOC,, 74, 165 (1975)], 7-ratio lithium [J, Am, Ceram, Soc, , 66, 11, 8
01 (1983).

JP-A-57-160963], etc., when dielectric porcelain is made using these sintering aids, the grain size is large and non-uniform, reaching several tens of micrometers in some cases. Abnormal grain growth may also occur. As a way to improve this drawback.

JP-A No. 61-25156.1 discloses copper oxide, zinc oxide and/or cadmium oxide i in an amount of 0.2 to 5.5 mol.
%, a sintered body with almost theoretical density can be obtained at a sintering temperature of 120 DC or less, and yet.

The possibility of controlling its microstructure is disclosed.

However, the dielectric porcelain obtained by this method has a temperature of 1200C
Although it can be sintered under the following conditions, the grains are fine and uniform, and the electrical properties (for example, dielectric constant, insulation resistance, and dielectric loss) are relatively good, there remain some problems with reliability.

To address this problem, it is known that adding a rare earth oxide to barium titanate improves reliability. J.
Am, Ceram, Soc,, 4 b, 5, 1
97 (1963), barium titanate contains 0.5 mo
1575-1500'C with addition of 1% lanthanum oxide
It has been reported that the reliability of multilayer capacitors sintered with In this method, the sintering temperature is high;
Grain size tends to become uneven.

In practical terms, the electrical characteristics are also unstable.

(Problems to be Solved by the Invention) Therefore, in the prior art, it has been found that a porcelain composition of 1200C or less is transparent, has uniform grains, has good electrical properties, and satisfies reliability at the same time. Not yet.

(Means for Solving the Problems) As a result of intensive research, the present inventors found that copper oxide, zinc oxide, and rare earth oxides were added to barium titanate.

Furthermore, when a specific amount of one or more selected from iron oxide, cobalt oxide, and nickel oxide is added.

1200tl? At less than sintering temperature, the microstructure is uniform.

The present inventors have discovered that a sintered body having a density of 95% or more of the theoretical density can be obtained, and at the same time the reliability is dramatically improved.

That is, in the present invention, the first component is 85.6 to 99.
49 mol% barium titanate, 0 as second component
．． 2 to 5.5 mol% zinc oxide, 0.5 mol% as the third component.
01-0.7 mol% iron oxide, cobalt oxide.

A dielectric ceramic composition consisting of one or more strains selected from nickel oxides, 0.1 to 1.2 mol% of rare earth oxide as a fourth component, and 0.2 to 7 mol% of copper oxide as a fifth component. It is related to.

Barium titanate with specific amounts of zinc oxide, rare earth oxides,
Dielectric ceramic compositions fired with the addition of copper oxide and one or more selected from iron oxide, cobalt oxide, and nickel oxide have a higher dielectric constant and a smaller grain size than those without the addition of rare earth oxides. Uniform and extremely reliable.

Furthermore, by combining a specific amount of one or more selected from titanate, zirconate, and stannate as the sixth component, the dielectric constant near room temperature can be increased to 12,000 or more without impairing the above properties. It is possible to increase it to

The barium titanate used in the present invention is produced using a solid phase method.

Any method such as a liquid phase method (eg, oxalate method, alkoxide method) or the like may be used. Average particle size is 1μ
When using particles with a uniform particle size distribution of 1 m or less,
- Highly reliable porcelain with a uniform microstructure and good electrical properties can be obtained.

In the present invention, additives include zinc oxide, rare earth oxides, copper oxide, iron oxide, and cobalt oxide.

Although nickel oxide can be used as is.

Inorganic acid salts such as hydroxides and carbonates, and oxalate salts.

Any organic salt such as an alkoxide can be used as long as it decomposes to an oxide below the sintering temperature. Copper oxides include monovalent, divalent, and monovalent.

Any coexisting divalent compounds can be used.

Manganese oxide is divalent, trivalent, and tetravalent.

It is possible to use any of the chemical compounds and those in which they coexist. Examples of rare earth acids include neodymium oxide, samarium oxide, and gadolinium oxide.

Any of dysprosium oxide, holmium oxide #lt (hierubilum, hythurium oxide, etc.) can be used.

Further, the oxide added as the sixth component in the present invention is preferably in the form of a common composite oxide of stannate, titanate, or zirconate.

The proportion of barium titanate in the porcelain composition of the present invention is:
It is in the range of 85.6 to 99.49 mo1%. If the proportion is more than 99.49 mol%, sintering will be difficult at temperatures below 1200C; if the proportion is less than 85.6 mol, significant deformation of the base material will occur during sintering.

The preferable range is 92.8 to 98.45 mol, which provides good sinterability and hardly causes deformation of the base material.

The proportion of zinc oxide is 0.2 to 5.5 as Zn0O type.
The range is m06. If it exceeds 5.5 mol, 1
It is difficult to sinter at temperatures below 200C), resulting in non-uniform grains and a decrease in insulation resistance. Less than 0.2 mol.

Almost no effect of addition is observed, and dielectric loss also increases. The most preferable range, which provides good sinterability and sufficiently high insulation resistance, is 0.6 to 3 mol%.

What is the proportion of iron oxide, cobalt oxide, and nickel oxide?

Each Fe 205. Co504. Ni 20
3 (7) Shape and size range from 0.01 to 0.7 mol'A. o, 7 moL'4 If there are more than 120
Sintering at temperatures below 0'C is difficult, and when manufacturing a multilayer capacitor, delamination between the internal electrode and the current-visitor layer is significant. Furthermore, if the content is 0.01 rnol% or less, almost no effect of addition is observed, resulting in low reliability. The most preferable range in which delamination does not occur and reliability and light intensity are good is in the range of 0.05 to 0.5 mol %.

Me 203 (Me
= La.

Nd, Sm, Gd, Dy, Ho, Er, Tm, etc.)
The amount is in the range of 0.1 to 1.2 mol%. Reliability improves as the amount added increases, but 1.2 mol
%, the microstructure tends to become non-uniform and abnormal grain growth is also observed.

If it increases further, sintering at 1'2000 or less becomes difficult. If the amount is less than 0.1 mol, hardly any effect of addition is observed and reliability is low. The most preferable range is 0.5 to Q, 7m+)t to obtain high reliability without impairing sinterability.
%.

The proportion of copper oxide is in the range of 0.2 to Vmol as CuO. If it is more than 7 mol%, delamination will be significant and the dielectric loss will also be large.

In addition, if the grain size during sintering is uneven and large,
Reliability also deteriorates significantly. If the amount is less than 0.2 mol, low-temperature sintering becomes difficult. The most preferable range that does not cause delamination and provides sufficiently high reliability is 0.
It is 6 to 5 mo1%.

Additionally, in a preferred embodiment, a stannate.

By adding 2 to 20 mol of a composite oxide selected from titanates and zirconates and having a size of 7t1m or more per 100 mol of the total of the first component, second component, third component, and fourth component. , it is possible to increase the dielectric constant near room temperature to 12,000 or more. If the amount is less than 2 mol, the effect of addition is not so noticeable and the dielectric constant near room temperature is low.
However, if it exceeds 20 moles, sintering at 1200C or lower becomes difficult. When using calcium stannate or a mixture thereof as a barium stannate solution, a product with a large dielectric constant can be easily obtained.

(Example〕 The present invention will be explained in detail below using examples.

Example 1 Barium titanate, zinc oxide, #II copper steel and iron oxide, cobalt oxide, nickel oxide and acid 1hineodymium, U
(Hisamarium, [Aihi Dysprosium.

Weighed holmium oxide, hierubilum acid, and thulium oxide in the proportions shown in Table 1, and added pure water.

Mixing was performed using a wet ball mill. Mixture of gold ingredients, dry, crushed nine barley, acrylic resin and trichloroethane as binder? A paste was prepared using zirconia as a ball media as a solvent. From the nine paste obtained, a green sheet with a thickness of 28 μm was created using the doctor blade method, and a multilayer capacitor with five effective layers was prototyped using the screen printing method. Ag/Pd = 70 as internal electrode
/30 ingredients were used. After removing the binder from this chip, it was sintered at 1100C for 5 hours. The resulting multilayer capacitor has a dielectric layer thickness of 18 μm and an effective internal surface area of 0.009 cm. Next, the electrical properties of the silver electrode were measured using a dead metal as an external electrode.

Visit rate and dielectric loss were measured using an LCR meter.

Measured under the conditions of 1KHz, IV, 20C. Insulation resistance was measured using a high insulation resistance tester and was measured by applying a voltage of 50 cm for 1 minute. The grain size was determined by polishing the cross section of the multilayer capacitor, etching it with 1:1 hydrochloric acid, and then taking a scanning electron micrograph.

Find friends using the line intercept method. A high temperature load test was conducted to evaluate reliability, and the lifespan was 125C.

It was expressed as the time required to reach a failure rate of 63% under a 200VDC load condition. The measurement results are shown in Table 2.

In Table 2, sample numbers 9, 10.11 are comparative examples in which the third component, the fourth component, or both were not added. In this case, although no deterioration in the electrical characteristics of the capacitor was observed, the high temperature load life was 106.121.2.
It is short at 5 hours.

On the other hand, the third component is iron oxide, M (hycobalt, nickel oxide), and the fourth component is neodymium,
samarium oxide, dysprosium oxide. If holmium oxide, erbium oxide, or thulium oxide is added, the capacitance and dielectric loss will decrease.

It can be seen that the high temperature load characteristics are significantly improved without causing a decrease in electrical properties such as insulation resistance.

Table 1 (Unit: mol%) Table
2 Example 2 As a friend additive that shifts the Curie point.

Barium stannate and calcium stannate are the first ingredients.

The sum of the second component, third component, fourth component, and fifth component is 100
It was weighed so as to have the ratio shown in Table 5 based on the mol, and added as the sixth component. A multilayer capacitor was prototyped in the same manner as in Example 1, and its electrical properties were measured. Table 4 shows the results.
Shown below.

In Table 3, sample numbers 2 and 6 are comparative examples in which the amount of the third component added is different from that of the present invention, and as can be seen from Table 1, the sintered body density is low and the electrical properties cannot be measured. Sample numbers 1, 3, and 4.5 are those of the present invention, and the content i at 5.20C was obtained by weighting barium stannate and calcium stannate.
It is possible to increase t. Similar effects can be obtained by using other shifters such as strontium stannate, lead stannate, strontium titanate, barium zirconate, calcium zirconate, strontium zirconate, and lead zirconate. The grain size of the element body is about 4 μm, and it has a uniform microstructure, and no deterioration of electrical properties such as dielectric loss or insulation resistance is observed. It can be seen that a highly reliable multilayer capacitor with a long life under high-temperature load conditions can be obtained.

Table 4 In the above examples, barium titanate contains Ba and Ti.
O, OSmolS was used with a molar ratio of approximately 1.
Good characteristics can be obtained even if the ratio on m is off.

(Effects of the Invention) From the above, the ferroelectric ceramic composition of the present invention can be sintered at temperatures below 12001, has uniform grain size, and has low electrical loss, insulation resistance, etc. It also has good electrical properties and extremely high reliability. Furthermore, without impairing these properties, the dielectric constant at room temperature can be increased to over 12,000.
It is extremely useful as a dielectric composition for multilayer ceramic capacitors, and has great industrial value.

1 other person

Claims (6)

[Claims] (1) 85.6-99.49 mol% barium titanate as the first component, 0.2-5.5 mol% as the second component
l% zinc oxide, 0.01-0.7 mo as third component
1% of one or more selected from iron oxide, cobalt oxide, and nickel oxide, 0.1 to 1.2 mol as the fourth fraction
% rare earth oxide, 0.2-7 mol% as the fifth component
A dielectric ceramic composition consisting of copper oxide. (2) The first component is 92.8-98.45 mol%, the second component is 0.6-3 mol%, and the third component is 0.05-0.
5 mol%, the fourth component is 0.3 to 0.7 mol%, and the fifth component is 0.6 to 3 mol%. (3) The dielectric ceramic composition according to claim 1 or 2, wherein the third component is cobalt oxide. (4) The fourth component is selected from samarium oxide, dysprosium oxide, holmium oxide, and erbium oxide.
The dielectric ceramic composition according to claim 1 or claim 2, wherein the dielectric ceramic composition contains at least one species. (5) 100m of dielectric ceramic composition according to claim 1
ol, as the sixth component, stannate, titanate,
2 to 20 mo of one or more selected from zirconates
A dielectric ceramic composition containing l. (6) The dielectric ceramic composition according to claim 5, wherein the sixth component is barium stannate and/or calcium stannate.