JP3106367B2 - Non-reducing 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, and more particularly, to a Pb composite perovskite-type dielectric ceramic material as a main component, which has an auxiliary component effective for preventing reduction of the dielectric ceramic. The present invention relates to a non-reducible dielectric porcelain composition which is contained and used for a porcelain multilayer capacitor, for example, by firing simultaneously with an internal electrode material made of a base metal.

[0002]

2. Description of the Related Art Conventionally, a multilayer ceramic capacitor using a Pb-based high-permittivity ceramic material as a dielectric material and an Ag-Pd-based or Pt-based alloy as an internal electrode has been required to have a small size, a large capacity, and high reliability. It has been widely used in various consumer and industrial electronic circuits. In order to manufacture a porcelain multilayer capacitor, for example, a porcelain green sheet having a thickness of 30 to 50 μm is prepared by a doctor blade method or the like, and a metal conductor layer serving as an internal electrode is formed on the porcelain green sheet. Laminating, thermocompression bonding and integration, firing the integrated product in a natural atmosphere at, for example, 1050 to 1200 ° C. to form a sintered body, and an external lead-out electrode connected to an internal electrode on an end face of the sintered body. Was baked.

[0003]

In the conventional porcelain multilayer capacitor, it is necessary to satisfy the following two conditions as the material of the internal electrode. First, since the dielectric ceramic material and the internal electrode material are fired at the same time, they have a melting point higher than the sintering temperature of the dielectric ceramic material. Second, they are oxidized even in an oxidizing high-temperature atmosphere. And does not react with the dielectric. Noble metals such as platinum, gold, palladium or alloys thereof are available as electrode materials satisfying such conditions. Until now, these noble metals have been mainly used as internal electrode materials of porcelain multilayer capacitors. However, these electrode materials have excellent characteristics, but are expensive, so that the ratio of the electrode material cost to the porcelain multilayer capacitor is 30 to 70%.
%, Which was the biggest factor in raising costs.

On the other hand, as electrode materials other than noble metals, N
There are base metals such as i, Fe, Co, and Cu, but in recent years the demand for electronic components for high frequencies has increased, and as the internal electrodes of porcelain multilayer capacitors, those having high conductivity and low equivalent series resistance have been required. ing. For this reason, it has been considered to use Cu or a Cu-based alloy among base metal internal electrode materials. However, base metals such as Cu and Cu-based alloys are easily oxidized in a high-temperature oxidizing atmosphere, and do not function as electrodes. Therefore, in order to use these base metals for the internal electrodes of the porcelain multilayer capacitor, it is necessary to fire them together with the dielectric porcelain material in a neutral or reducing atmosphere.

However, the conventional dielectric porcelain material has a drawback that when it is fired in such a reducing atmosphere, it is significantly reduced and becomes a semiconductor.
Further, since the melting point of Cu or a Cu-based alloy is 1080 ° C. or lower, the sintering temperature of the dielectric material must be lower than that.

Therefore, when a metal having a low melting point, such as Cu or a Cu alloy, which is easily oxidized is used as an internal electrode of a multilayer capacitor, a dielectric material having excellent reduction resistance and sintering at a low temperature is required. It is.

Therefore, the main object of the present invention is to provide:
An object of the present invention is to provide a non-reducing dielectric ceramic composition which sinters at a low temperature of 080 ° C. or lower and does not cause deterioration of electrical characteristics even when firing in a reducing atmosphere.

[0008]

SUMMARY OF THE INVENTION The present invention was baked in advance
The resulting Te was _{Pb (Ni 1/3 Nb 2/3) O} 3, Pb (Zn
The mixing ratio (mol%) of _1/3 Nb _2/3 ) O ₃ and PbTiO ₃ is Pb (Ni _1/3 Nb _2/3 ) O ₃ 30.0 to 85.0, and Pb (Zn _1/3 Nb). _2/3) O _{3 1.0~69.0,}
And PbTiO ₃ for a certain main components 85.0 to 99.95 wt% in the range of 1.0 to 35.0, the general formula _{aLi 2 O + bRO + cB 2} O 3 + (10
0-abc) SiO ₂ (where RO is MgO, C
at least one selected from aO, SrO and BaO, a, b and c are represented by mol%), and a, b and c are respectively 0 ≦ a <20, 10 ≦ b <55, 0 ≦ It is a non-reducing dielectric ceramic composition containing 0.05 to 15.0% by weight of a subcomponent having c <40.

[0009]

Industrial Applicability The non-reducing dielectric ceramic composition according to the present invention has excellent reduction resistance, does not deteriorate in dielectric properties and insulation resistance even after reduction firing, and has a specific resistance of 10 ¹⁰ Ωcm or more.
It has a dielectric constant of 3000 or more and a dielectric loss of 3% or less, and has excellent sinterability and can be sintered at a low temperature of 1080 ° C. or less. Therefore, when the non-reducing dielectric ceramic composition according to the present invention is used as a ceramic laminated capacitor material, Cu or a Cu-based alloy can be used as an internal electrode material. Therefore, it is possible to obtain a ceramic porcelain capacitor which is inexpensive and has a small equivalent series resistance as compared with a conventional capacitor using a noble metal.

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.

[0011]

EXAMPLES Pb which is an industrial raw material as a starting material
₃ O ₄ , Nb ₂ O ₅ , TiO ₂ , NiO, ZnO and the like were prepared. These raw materials are weighed, and Pb (Ni
_1/3 Nb _2/3 ) O ₃ , Pb (Zn _1/3 Nb _2/3 ) O ₃ ,
Each was blended to become PbTiO _3, and 1
After wet mixing for 6 hours, the mixture was evaporated to dryness to obtain a mixed powder.
The obtained mixed powder is placed in a zirconia box,
iO ₃ was fired at 950 ° C., and the other compositions were fired at 850 ° C. for 2 hours to obtain a predetermined compound.

Next, the compound thus obtained is coarsely pulverized so as to pass through a 200-mesh sieve, and the compounding ratio of the dielectric materials in Sample Nos. 1 to 24 shown in Table 1 is adjusted to each desired ratio. Was blended in.

[0013]

[Table 1]

Further, in order to obtain a reduction inhibitor having an excellent effect of preventing reduction of dielectric ceramics when firing in a reducing atmosphere, for example, a reduction inhibitor in Sample Nos. 31 to 58 shown in Table 2 as a subcomponent. , The oxides, carbonates or hydroxides of each component are prepared and mixed with a ball mill.
After wet mixing and pulverizing for an hour, the powder was evaporated and dried to obtain a powder. The obtained powder was placed in an alumina crucible and left at a temperature of 1300 ° C. for 1 hour, and then rapidly cooled to vitrify. This is coarsely crushed so as to pass through a 200 mesh sieve,
A reduction inhibitor was prepared.

[0015]

[Table 2]

Next, the above dielectric materials are shown in Tables 1 and 2 below.
The reduction inhibitor was added at the ratio shown in Table 1. In this case, in sample numbers 1 to 24, sample numbers 32 to 3 were used as reduction inhibitors.
Similar to _{5,56~58, 5Li 2 O + 20BaO +} 1
5CaO + 5SrO + 5MgO + 25B ₂ O ₃ + 25S
An iO ₂ reduction inhibitor was added. In addition, sample numbers 31 to
In 58, as the dielectric material, 7
0Pb (Ni _1/3 Nb _2/3 ) O ₃ + 10Pb (Zn _1/3
A dielectric material of Nb _2/3 ) O ₃ + 20PbTiO ₃ was used.

A polyvinyl butyral-based binder and an organic solvent were added thereto, and the mixture was wet-mixed with a ball mill for 16 hours and formed into a sheet by a doctor blade method to obtain a porcelain green sheet. After drying the porcelain green sheet, the porcelain green sheet was cut into an appropriate size, a Cu electrode paste was printed on the cut porcelain green sheet by a screen printing method, and a predetermined number of sheets were stacked and thermocompressed to obtain a laminate. After cutting the obtained laminate to a predetermined standard, a Cu electrode paste was applied as an external electrode to obtain a raw unit. The raw unit is placed in an electric furnace adjusted to a reducing atmosphere in which a Cu electrode is not oxidized by using a mixed gas of N ₂ , H ₂ and H ₂ O, and is subjected to 820 to 1080 ° C.
For 2 hours to obtain a laminated ceramic capacitor.

The porcelain multilayer capacitor thus obtained was immersed in a cleaning solution and subjected to a sintering degree test to determine an optimum firing temperature. Further, 1 kHz, 1 Vrm at a temperature of 25 ° C.
The electrical characteristics of dielectric constant ε, dielectric loss tan δ, and insulation resistance at s were measured. Tables 3 and 4 show optimum firing temperatures and electrical characteristics of Sample Nos. 1 to 24 and Sample Nos. 31 to 58, respectively.

[0019]

[Table 3]

[0020]

[Table 4]

FIG. 1 is a three-component composition diagram showing the composition ratio of the dielectric material as the main component in Sample Nos. 1 to 58. In this case, the numbers in the figure represent each sample number.

Further, FIG. 1 shows a region indicating the composition ratio of a dielectric material as a main component within the scope of the present invention by a pentagon having composition points A, B, C, D and E as vertices. Indicated. That is, the main component in the non-reducing dielectric ceramic composition according to the present invention is [Pb (Ni _1/3 Nb _2/3 ) O].
₃ ] x + [Pb (Zn _1/3 Nb _2/3 ) O ₃ ] y + [Pb
When TiO ₃ ] z (where x + y + z = 1.00), x, y and z are represented by A (0.64, 0.01, 0.35) B ( 0.30, 0.35, 0.35) C (0.30, 0.69, 0.01) D (0.85, 0.14, 0.01) E (0.85, 0.01, 0.14) in the range of a pentagon surrounded by the five composition points.

In order to obtain the main components in the non-reducing dielectric ceramic composition according to the present invention, for example, Pb ₃ O ₄ : 66.60 to 69.20 (% by weight), NiO: 2.17 to 6 .27 (wt%), ZnO: 0.08 to 5.45 _{(wt%), Nb 2 O 5:} 17.38~25.63 ( wt%),
And each oxide of TiO ₂ : 0.23 to 8.47 (% by weight) may be used.

The reasons for limiting the ranges of the main component and the subcomponent in the present invention as described above are as follows. First, the reasons for limiting the main components will be described. Outside the line connecting the composition points A and B in FIG. 1, that is, in the range where PbTiO ₃ is more than 35 mol%, as shown in Sample Nos. 1 and 2, the dielectric loss becomes larger than 3.0%, which is not preferable. . Similarly, outside the line connecting composition points B and C, that is, P
b (Ni _1/3 Nb _2/3 ) O _{3 in} a range of less than 30 mol%,
Alternatively, outside the line connecting the composition points A and E, that is, Pb
Even in the range where (Zn _1/3 Nb _2/3 ) O ₃ is less than 1 mol%, the dielectric loss becomes larger than 3.0% as shown in Sample Nos. 10 and 11 and Sample Nos. 6 and 7. Not preferred. Further, outside the line connecting composition points C and D, that is, the range where PbTiO ₃ is less than 1 mol%, or outside the line connecting composition points D and E, that is, Pb (Ni _1/3 Nb)
_2/3 ) In the range where O ₃ is more than 85 mol%, sample No. 1
As shown in 8, 19, 20 and Sample No. 13, the dielectric constant is less than 3000, which is not preferable.

Next, the reason why the reduction inhibitor as an auxiliary component is limited will be described. As shown in sample numbers 44, 45, 46 and 47, when b is less than 10 mol%,
The insulation resistance is less than 10 ¹⁰ Ωcm, and the dielectric loss is more than 3.0%, which is not preferable. Further, as shown in sample numbers 36, 37, 38 and 39, b is 55
If it is at least mol%, the firing temperature will exceed 1080 ° C., which is not preferable. As shown in sample No. 52, the amount of Li ₂ O becomes 20 mol% or more, or as shown in sample No. 54, B ₂ O
_{When the} content of ₃ is 40 mol% or more, the dielectric properties are remarkably impaired, and softening deformation occurs before sintering is completed. Further, as shown in Sample No. 31, the amount of the reduction inhibitor added was 0.0
If it is less than 5% by weight, the sintering of the dielectric is insufficient,
In addition, the reduction proceeds and the insulation resistance deteriorates. Further, as in Sample No. 58, when the amount of the reduction inhibitor exceeds 15% by weight, the dielectric constant is less than 3000, which is not preferable.

In the non-reducing dielectric ceramic composition according to the present invention, 2 mol% of the
Up to MnO ₂ , Fe ₂ O ₃ , Cr ₂ O ₃ or Co
The addition of O does not impair its properties at all.

In the above-mentioned embodiment, as a reduction inhibitor, a premixed at a predetermined ratio, heat-treated at a high temperature, melted, pulverized and vitrified was added to the main component and mixed. However, as a method of adding the reduction inhibitor,
Powder which has been previously mixed in a predetermined ratio and heat-treated may be added, or a reduction inhibitor may be added individually to the main component.

When firing a laminate composed of a Pb composite perovskite dielectric material and a Cu-based internal electrode material, it is necessary to keep the dielectric in an oxygen atmosphere in which the dielectric is not reduced and the internal electrode is not oxidized. is there. That is, when the dielectric material is reduced, the insulation resistance decreases, and when the internal electrode is oxidized, a problem such as an increase in equivalent series resistance occurs. In any case, the function as a capacitor is lost.

On the other hand, according to the present invention, since the oxygen partial pressure of the sinterable atmosphere spreads particularly to the low oxygen partial pressure side by adding the reduction inhibitor to the dielectric material, the oxygen partial pressure is strictly controlled. It is possible to obtain a product with a high non-defective rate under an appropriate reducing atmosphere without controlling the temperature. That is, the non-reducing dielectric ceramic composition according to the present invention is not easily reduced even when fired in a reducing atmosphere. And, the porcelain made of such a composition does not deteriorate in dielectric properties and insulation resistance,
The specific resistance is 10 ¹⁰ Ωcm or more, the dielectric constant is 3000 or more, and the dielectric loss is 3% or less. Furthermore, the firing temperature of the non-reducing dielectric ceramic composition according to the present invention is 1050 ° C. or less. Therefore, if the non-reducing dielectric ceramic composition according to the present invention is used as a material for a multilayer capacitor, Cu or Cu
A system alloy or the like can be used. As a result, the cost is significantly reduced as compared with the case where a noble metal electrode such as a conventional Pd-Ag or Pt-based electrode is used, and a multilayer ceramic capacitor having a small equivalent series resistance is obtained.

[Brief description of the drawings]

FIG. 1 is a three-component composition diagram showing a range of a main component in a non-reducing dielectric ceramic composition according to the present invention.

Continuation of the front page (72) Inventor Yukio Sakabe 2-26-10 Tenjin, Nagaokakyo-shi, Kyoto Murata Manufacturing Co., Ltd. (56) References JP-A-2-9753 (JP, A) JP-A-2 -155115 (JP, A) JP-A-62-254307 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C04B 35/42-35/49 CA (STN) REGISTRY (STN)

Claims (1)

(57) [Claims] 1. Pb (Ni _1/3 N) obtained by calcining in advance
b _2/3 ) O ₃ , Pb (Zn _1/3 Nb _2/3 ) O ₃ and P
The mixing ratio (mol%) of bTiO ₃ is Pb (Ni _1/3 Nb _2/3 ) O ₃ 30.0-85.0, Pb (Zn _1/3 Nb _2/3 ) O ₃ 1.0-69. .0,
And 85.0 to 99.95% by weight of the main component in the range of 1.0 to 35.0 of PbTiO ₃ , and the general formula is aLi ₂ O + bRO + cB ₂ O ₃ + (100−
abc) SiO ₂ (where RO is MgO, Ca
At least one selected from O, SrO and BaO
Types, a, b, and c are represented by mol%), and a, b, and c each represent a subcomponent satisfying 0 ≦ a <20, 10 ≦ b <55, and 0 ≦ c <40 by 0.05 to A non-reducing dielectric ceramic composition containing 15.0% by weight.