JP2605987B2 - Dielectric porcelain composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a non-reducing dielectric ceramic composition for use in a ceramic capacitor, particularly a laminated ceramic capacitor having an internal electrode made of a base metal such as nickel.

[0002]

2. Description of the Related Art Conventionally, when obtaining a multilayer electronic component such as a multilayer capacitor, a sintered body obtained by integrally firing an electrode material constituting an internal electrode and a dielectric ceramic has been used. When a multilayer capacitor is manufactured, a conventional dielectric material containing BaTiO ₃ as a main component is fired at 1300 to 1500 ° C., so that noble metal such as Pt or Pd which does not melt at such a temperature is used as an internal electrode material. Was used. However, there is a problem that these noble metals are expensive, and when the number of internal electrodes is increased in order to increase the capacity, the cost is significantly increased. Accordingly, attempts have been made to use inexpensive base metals such as nickel as the internal electrode material. However, when an internal electrode made of a base metal such as nickel is used, the internal electrode material is easily oxidized and must be fired in a reducing atmosphere. There was a problem of losing. In order to solve such a problem, for example, MgO or MnO is added to BaTiO ₃ (Japanese Patent Laid-Open No. 57-71866), and CaZrO ₃ is added to this system.
(Japanese Patent Application Laid-Open No. 62-157603) has been proposed.

[0003]

However, the dielectric disclosed in the above prior art has a problem that the relative dielectric constant decreases with time and the initial characteristics cannot be maintained. When the CR product is increased, the temperature change rate of the dielectric constant (however, in the range of −55 ° C. to + 125 ° C., based on + 25 ° C.) becomes larger. I. A. Standards (Electroni
c IndustryAssociation Sta
There is also a problem that it tends to deviate from ± 15% of the value of (ndard). An object of the present invention is to provide a non-reducing dielectric ceramic composition having excellent relative dielectric constant aging characteristics, excellent CR product, and small capacitance temperature change while maintaining a high relative dielectric constant and a small dielectric tangent. Is to do.

[0004]

Means for Solving the Problems The dielectric ceramic composition of the present invention contains a component represented by the following composition formula as a main component. (1-abctd-t) BaTiO ₃ + aCaTi
O ₃ + b {(1-x) BaZrO ₃ + xSrZrO ₃ }
+ CMgO + dMnO + tRe ₂ O ₃ Where Re is Y, Gd, Dy, Ho, Er or Y
and at least one of b. In addition, the non-reducing dielectric ceramic composition of the present invention contains Si based on 100 parts by weight of the main component.
O _2, the Li ₂ O or B ₂ O additive consisting of at least one ₃ containing 0.1 to 5.0 parts by weight.

[0005]

In the above composition formula, the reason why a is set to 0.05 or less is that when CaTiO ₃ is added in excess of 5 mol%, the dielectric constant changes with temperature in the temperature range of -55 ° C. to + 125 ° C. This is because the rate (hereinafter, the temperature change rate of the dielectric constant) exceeds ± 15%. Next, b is 0 <b ≦ 0.05.
Is between -55 ° C and +1 outside that range.
If the temperature change rate of the dielectric constant in the temperature range of 25 ° C. exceeds ± 15%, or if the amount of SrZrO ₃ or BaZrO ₃ added is large, the CR product decreases to 1000 or less, the insulation resistance becomes insufficient, and the multilayer capacitor becomes insufficient. This is because it cannot be used. Further, the reason why c is set to be between 0.005 and 0.08 is that if the mixing ratio of MgO is out of this range, the CR product is reduced to 1000 or less, and the insulation resistance becomes insufficient. is there. Further, d is set in the range of 0.005 to 0.02 because, when the mixing ratio of MnO is less than 0.5 mol%, −
This is because the temperature change rate of the dielectric constant in the temperature range of 55 ° C. to + 125 ° C. exceeds ± 15%, and if it exceeds 2.0 mol%, the CR product decreases. Furthermore, when t is 0.
The range of 005 to 0.02 is that of Re ₂ O ₃
When the compounding ratio is less than 0.5 mol%,
The temperature change rate of the dielectric constant in the temperature range of + 125 ° C. is ±
This is because it exceeds 15%, and if it exceeds 2.0 mol%, the sinterability deteriorates and sintering becomes difficult at a temperature of 1250 ° C. or lower. In the present invention, the addition of an additive composed of at least one of SiO ₂ , LiO _{2 and} B ₂ O ₃ is for enhancing sinterability. However, if the compounding ratio of the additive is less than 0.1 part by weight with respect to 100 parts by weight of the main component, sintering is not performed even at a temperature of 1300 ° C., and the additive is 5.0 parts by weight with respect to 100 parts by weight of the main component. When added in excess of the above, the dielectric constant is significantly reduced. Therefore, the content of the additive with respect to 100 parts by weight of the main component is 5.
0 parts by weight is the upper limit. In the present invention, in particular, CaTiO
_3, by adding BaZrO ₃ or SrZrO ₃ , there is little change with time in the dielectric constant, and by adding the above-mentioned specific additive, it is possible to perform calcination at a temperature of 1250 ° C. or less. As is clear from the examples, a non-reducing dielectric ceramic composition having a small rate of change in dielectric constant with temperature and exhibiting a sufficiently large CR product can be obtained.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be described in detail based on embodiments. First, the starting materials shown in Tables 1 to 4 were weighed so as to have the ratios in the table, and an organic binder was further added thereto and wet-mixed in a ball mill for 24 hours to prepare a slurry. Using this slurry, a green sheet having a thickness of 30 to 40 μm was prepared by a sheet forming method such as a doctor blade method. Further, an internal electrode paste composed of nickel powder and an organic vehicle was prepared. The paste was screen-printed on a green sheet, laminated, and then thermocompression bonded to produce a laminate. The obtained laminate was cut into a suitable size, and kept in an air atmosphere at 300 ° C. for 2 hours to remove the binder, and then N ₂ / H ₂ / H ₂ O
It baked for 2 hours at each calcination temperature shown in Tables 3-4 in an atmosphere. A paste made of an alloy powder of silver and palladium was applied to the end face of the fired chip, and baked at 700 ° C. to 900 ° C. to form an end face electrode, thereby obtaining a multilayer ceramic capacitor. For the above ceramic capacitor, the permittivity ε, tan δ, the temperature change rate TC of the permittivity,
The insulation resistance IR and the aging rate of the capacitance were measured.
The measurement conditions are as follows. Dielectric constant ε: 25 ° C, AC 1 kHz, 1.0 V _rms
I went in. tan δ: 25 ° C, AC 1 kHz, 1.0 V _rms
I went in. Temperature change rate TC of dielectric constant: measured in a range of -55 ° C to + 125 ° C. The test was performed at an alternating current of 1 kHz and 1.0 V _rms . Insulation resistance IR: A value obtained by applying a voltage of 50 V and elapse of 2 minutes, and the CR product is a value obtained by multiplying the IR by the capacitance. Aging rate of capacitance: Change rate of capacitance after heating at 150 ° C. for 1 hour, and after 24 hours and 240 hours. Tables 5 and 6 show measurement results. Tables 5 and 6 also show the CR product.

[0007]

[Table 1]

[0008]

[Table 2]

[0009]

[Table 3]

[0010]

[Table 4]

However, the compositions A and B of the additives in Tables 3 and 4 are as follows. Composition A: 50 parts by weight of SiO _2, 20 parts by weight of Li ₂ O, 10 parts by weight of BaO, 10 parts by weight of CaO, SrO
... 10 parts by weight. Composition B: B ₂ O ₃ 20 parts by weight, BaO 40 parts by weight,
SiO ₂ ... 30 parts by weight, Li ₂ O ... 10 parts by weight.

[0012]

[Table 5]

[0013]

[Table 6]

As is apparent from Tables 5 and 6, CaTiO
_When the compounding ratio of ₃ is increased (sample numbers 8 to 11), the aging rate decreases. Further, in the sintered body of sample No. 11, the mixing ratio of the main component is out of the range of the present invention, so that the temperature change rate of the dielectric constant is large. In the sintered body of sample No. 1, Ba
Since both ZrO ₃ and SrZrO ₃ are not added, the aging rate is large. Sample No. 5
In No. 7, since the mixing ratio of BaZrO ₃ and SrZrO ₃ is out of the range, the temperature change rate of the dielectric constant becomes large,
In sample No. 7 in which the amount of added rZrO ₃ was large, the CR product was 90.
It is as small as 0. In addition, since no additive was added to the sintered body of Sample No. 12, sintering was insufficient even at 1300 ° C., and the above measurements could not be performed. Sample number 1
The sintered body of No. 4 has a low dielectric constant of 2200 because the content of the additive is as high as 6.0% by weight. In the sintered bodies of Sample Nos. 18 and 19, the CR product was as low as 1000 or less because the mixing ratio of MgO in the main component was out of the range of the present invention. Sample number 2
No. 0-55 ° C.
It can be seen that the temperature change rate of the dielectric constant at -19.5% is as large as -19.5%. Further, in the sintered body of sample No. 22, the compounding ratio of MnO was as high as 2.5 mol%, so that the CR product was 700%.
And has declined.

In the sintered body of sample No. 23, since the rare earth oxide is not contained, the temperature change rate of the dielectric constant is +125.
It was considerably large at -16.0% at ° C. In addition, the sintered body of Sample No. 25 was as high as 2.5 mol% in the main component of the rare earth oxide, and did not sinter even at 1300 ° C. In the sintered bodies of Sample Nos. 26 and 27, since the rare earth oxide is out of the range, the temperature change rate of the dielectric constant is large in each case. On the other hand, the sintered bodies of the remaining sample numbers falling within the scope of the present invention all have a relatively high dielectric constant and a tan δ of 1.
It is as low as 8% or less, the CR product indicating the insulation resistance is as high as 2000 or more, and the temperature change rate of the dielectric constant is less than ± 15% in the temperature range of -55 ° C. to + 125 ° C. and the aging rate is −.
It turns out that it is less than 2.0% / decade. That is, the sintered body within the scope of the present invention shows excellent dielectric properties. Of the above compositions, oxides such as MgO and MnO are not limited to these, and for example, MgCO ₃ ,
Carbonate such as MnCO ₃ may be used.

[0016]

As described above, according to the present invention, the specific additive is contained in an amount of 0.1 to 5.0 parts by weight based on 100 parts by weight of the main component of the specific composition. 125
It is possible to provide a dielectric porcelain that can be fired at a temperature of 0 to 1300 ° C. and that has sufficient dielectric properties. Therefore, when the dielectric porcelain composition of the present invention is used, N
A base metal such as i can be used as an internal electrode material, which makes it possible to provide an inexpensive multilayer ceramic electronic component.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Yasuyuki Naito 2-26-10 Tenjin, Nagaokakyo-shi, Kyoto Co., Ltd. Inside Murata Manufacturing Co., Ltd. Murata Manufacturing Co., Ltd.

Claims (1)

(57) [Claims] 1. The composition formula is: (1-a-b-c-dt) BaTiO ₃ + aCaTi
O ₃ + b {(1-x) BaZrO ₃ + xSrZrO ₃ }
+ CMgO + dMnO + tRe ₂ O ₃ (Where Re is Y, Gd, Dy, Ho, Er or Y
b) and 0.1 to 5.0 parts by weight of an additive composed of at least one kind of SiO ₂ , Li ₂ O or B ₂ O ₃ with respect to 100 parts by weight of the main component represented by (b). A dielectric porcelain composition comprising: