JP2967440B2 - Dielectric ceramic composition for temperature compensation - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a temperature-compensating dielectric ceramic composition, and more particularly to a temperature-compensating dielectric ceramic composition used as a material for a dielectric ceramic of a multilayer capacitor.

[0002]

2. Description of the Related Art Heretofore, as this kind of dielectric ceramic composition for temperature compensation, there has been an MgTiO ₃ —CaTiO ₃ based composition.

[0003]

However, MgT
The iO ₃ -CaTiO ₃ based ceramics with the composition of, the firing temperature is as high as 1300 ° C. or more, is reduced further calcined at low oxygen partial pressure neutral or reducing, has the property of semiconductive I was Therefore, when such a composition is used as a material for a multilayer capacitor or the like,
As a material for the internal electrode, a noble metal such as Pt or Pd, which does not melt at the temperature at which the dielectric ceramic material sinters and does not oxidize even under a high oxygen partial pressure that does not turn the dielectric ceramic material into a semiconductor, must be used. Did not. Therefore, it has been a great hindrance to reducing the price of the manufactured multilayer capacitor.

Therefore, in order to solve the above-mentioned problem, it has been desired to use an inexpensive base metal such as Ni or Cu as a material for the internal electrodes. However, when such a base metal is used as a material for an internal electrode and fired under a conventional oxidizing atmosphere, the electrode material is oxidized or melted. Therefore, since such a base metal is used as a material for an internal electrode, it does not turn into a semiconductor even when fired at a low temperature in a neutral or reducing atmosphere having a low oxygen partial pressure, and is sufficiently used as a dielectric material for a capacitor. There is a need for a dielectric material having an excellent specific resistance and excellent dielectric properties.

A dielectric porcelain composition for solving this kind of problem is disclosed in Japanese Patent Application Laid-Open No. 1-102806. Since this dielectric porcelain composition can be fired in neutral and reducing atmospheres with low oxygen partial pressure,
Using this, a multilayer capacitor for temperature compensation using a base metal such as Ni or Cu as an internal electrode can be manufactured.
However, the dielectric porcelain composition disclosed in JP-A-1-102806 can solve the above-mentioned problems with respect to the firing temperature and the temperature coefficient of the dielectric constant, but has a Q value of 1 MHz.
It is as small as 2000 or less in z.

[0006] Therefore, the main object of the present invention is to provide a neutral or reducing atmosphere having a low oxygen partial pressure.
Sintered at a low temperature of 050 ° C. or less, without reduction, the absolute value of the temperature coefficient of capacitance is 100 ppm / ° C. or less, the Q value is 2500 or more, and the specific resistance at 20 ° C. is 1 ×
An object of the present invention is to provide a dielectric ceramic composition for temperature compensation, which is 10 ¹³ Ωcm or more and can use an inexpensive metal such as Cu as a material for an internal electrode.

[0007]

The present invention includes barium oxide, strontium oxide, silicon oxide, zirconium oxide and aluminum oxide, and has a content of barium oxide and strontium oxide of (Ba _1-a Sr _a ) O (where , 0 <a ≦ 0.9), and the content of zirconium oxide and aluminum oxide is expressed as 重量 (Z
rO ₂ ) _1-b (Al ₂ O ₃ ) _b ｝ (where 0 ≦ b ≦
0.5) and converted to SiO ₂ , and the content of silicon oxide converted to SiO ₂ and converted to Z parts by weight (where X +
(Y + Z = 100) In the three-component composition diagram, (X, Y,
Z) is A (50, 2.5, 47.5), B (5
0, 30, 20), C (15, 65, 20),
With respect to the main component within the range surrounded by polygons A, B, C, and D having vertices at each composition point of D (15, 2.5, 82.5), TiO ₂ is added as a subcomponent by V weight. Department (but
0 ≦ V ≦ 10) and B ₂ O ₃ in W parts by weight (provided that 0 <W
≦ 5) A dielectric ceramic composition for temperature compensation added.

[0008]

According to the present invention, sintering is performed at a low temperature of 1050 ° C. or less in a reducing atmosphere, the absolute value of the temperature coefficient of capacitance is 100 ppm / ° C. or less, and the Q value is 250
0 or more, and the specific resistance at 20 ° C. is 1 × 10 ¹³ Ωc
Thus, a dielectric ceramic composition for temperature compensation having characteristics of at least m can be obtained. Therefore, if this dielectric ceramic composition for temperature compensation is used as a material for a multilayer capacitor, Cu
Such a base metal can be used as a material for an internal electrode. Therefore, it is possible to eliminate an increase in the cost of the electrodes due to the increase in the capacity of the multilayer capacitor, and to provide a low-cost multilayer capacitor. Further, since the Q value is high, it can be used as a material for an LC filter, an RF module, and the like used in a microwave region.

The above objects, other objects, features and advantages of the present invention will become more apparent from the following detailed description of embodiments with reference to the drawings.

[0010]

EXAMPLE First, BaCO ₃ , which is a starting material of a main component,
SrCO ₃ , ZrO ₂ , Al ₂ O ₃ , SiO ₂ and TiO ₂ , B ₂ O ₃ as auxiliary components were prepared. These raw materials were weighed to have the composition shown in Table 1 to obtain a weighed material. Further, the compositions shown in Table 1 are shown on a three-component composition diagram and are shown in FIG. In FIG. 1, the composition points A, B, C,
The portion surrounded by D indicates that it is within the scope of the present invention.

[0011]

[Table 1]

The obtained weighed product was wet-mixed with a ball mill for 16 hours and then dried by evaporation to obtain a mixed powder. This mixed powder was calcined at 850 ° C. for 2 hours, 8 parts by weight of vinyl acetate was added as a binder, and the mixture was wet-mixed and pulverized again with a ball mill for 16 hours to obtain a pulverized product. The pulverized product was evaporated to dryness and sized to obtain a granular powder. The powder thus obtained was pressed with a dry press at a pressure of ² ton / cm ² and formed into a disc having a diameter of 20 mm and a thickness of 1.0 mm to obtain a molded product. Next, this molded product was fired in an N ₂ -H ₂ gas atmosphere under the temperature conditions shown in Table 2 for 2 hours to obtain a fired product. An In-Ga alloy was applied on both surfaces of the obtained fired product to form electrodes, and a capacitor as a sample was manufactured.

For the obtained sample, the dielectric constant ε, Q value,
The temperature coefficient α (ppm / ° C.) of the capacitance and the specific resistance ρ ₂₀ (Ωcm) at 20 ° C. were measured. The Q value was measured under the conditions of 1 MHz, 1 Vrms and 20 ° C.
The temperature coefficient α (ppm / ° C.) of the capacitance is 20 ° C.
C at ₂₀ ° C. and C at 85 ° C.
_{From 85, it} was obtained by the following equation.

[0014]

(Equation 1)

Further, the specific resistance at 20 ° C. ρ ₂₀ (Ωc
m) was determined from a current value flowing when a DC voltage of 500 V was applied at 20 ° C. Table 2 shows the results. In Tables 1 and 2, those marked with * are out of the scope of the present invention, and the others are within the scope of the present invention.

[0016]

[Table 2]

Next, the reason why the numerical values of the main components of the dielectric ceramic composition for temperature compensation of the present invention are limited will be described.
As shown in sample No. 6, in the three-component composition diagram, the composition point A
In the composition region outside the line segment connecting B and B, the Q value is 25
00 or less, which is not preferable. As in the sample number 5, in the three-component composition diagram, the Q value is 2500 or less in the composition region outside the line connecting the composition points A and D,
In addition, the specific resistance is less than 1 × 10 ¹³ , and the vitreous material floats on the surface of the sintered ceramic body, which is not preferable. As shown in Sample No. 7, in the three-component composition diagram, composition points B and C
In the composition region outside the line connecting the two, it is not preferable because a dense sintered body cannot be obtained even when firing at a temperature of 1050 ° C. As shown in sample number 8, in the three-component composition diagram, in the composition region outside the line connecting the composition points C and D, the Q value is 2500 or less, the specific resistance is less than 1 × 10 ¹³ , and the sintering is performed. It is not preferable because vitreous material floats on the surface of the porcelain body.

As shown in sample number 12, (Ba _{1 -a} S
r _a) when O of a is greater than 0.9, undesirably dense sintered body even if firing is not obtained at a temperature of 1050 ° C.. As in Sample No. 16, Δ (ZrO ₂ ) _1-b (A
l ₂ O ₃ ) _b } when b is greater than 0.5, 1050
It is not preferable that a dense sintered body cannot be obtained by firing at ℃. When TiO ₂ is larger than 10 parts by weight as in sample No. 19, the Q value becomes 2500 or less and the temperature coefficient of capacitance becomes larger than -100 ppm / ° C., which is not preferable. When B ₂ O ₃ is 0 parts by weight as in Sample No. 20, the Q value is 2500 or less, which is not preferable. When B ₂ O ₃ is more than 5 parts by weight as in Sample No. 22, the Q value is 2500 or less and the specific resistance is 1
Less than × 10 ¹³ and the temperature coefficient of capacitance is −10
It is not preferable because it is higher than 0 ppm / ° C.

On the other hand, according to the present invention, sintering is performed at a low temperature of 1050 ° C. or less in a reducing atmosphere, the absolute value of the temperature coefficient of capacitance is 100 ppm / ° C. or less,
Value is 2500 or more, and the specific resistance at 20 ° C. is 1 ×
A dielectric ceramic composition for temperature compensation having characteristics of 10 ¹³ Ωcm or more can be obtained. Therefore, if this dielectric ceramic composition for temperature compensation is used as a material for a multilayer capacitor, a base metal such as Cu can be used as a material for an internal electrode. Therefore, it is possible to eliminate an increase in the cost of the electrodes due to the increase in the capacity of the multilayer capacitor, and to provide a low-cost multilayer capacitor.
Further, since the Q value is high, it can be used as a material for an LC filter or an RF module used in a microwave region.

[Brief description of the drawings]

FIG. 1 is a three-component composition diagram showing the range of the mixing ratio of the components of the dielectric ceramic composition for temperature compensation of the present invention.

──────────────────────────────────────────────────続 き Continuation of front page (72) Inventor Yukio Sakabe 2-26-10 Tenjin, Nagaokakyo-shi, Kyoto Murata Manufacturing Co., Ltd. (56) References JP-A-1-102806 (JP, A) 63-55815 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) C04B 35/00

Claims (1)

(57) [Claims] 1. A barium oxide, strontium oxide, silicon oxide, include zirconium oxide and aluminum oxide, the content of the barium oxide and the strontium oxide _{(Ba 1-a Sr a)} O ( provided that, 0 <a ≦ 0 .9)
The content of the zirconium oxide and the aluminum oxide is expressed as 重量 (ZrO ₂ )
_1-b (Al ₂ O ₃ ) _b ｝ (where 0 ≦ b ≦ 0.5), which is defined as Y parts by weight, and the content of the silicon oxide is SiO
₂ and converted to Z parts by weight (however, X + Y + Z
= 100) In the three-component composition diagram, (X, Y, Z)
Is the peak of each composition point of A (50, 2.5, 47.5) B (50, 30, 20) C (15, 65, 20) D (15, 2.5, 82.5) With respect to the main component in the range surrounded by polygons A, B, C, and D, TiO ₂ is V parts by weight (where 0 ≦ V ≦ 10) and B ₂ O ₃ is W parts by weight ( However, 0 <W ≦ 5) The dielectric ceramic composition for temperature compensation added.