JP2669184B2 - 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 porcelain composition, and more particularly, to a non-reducing dielectric porcelain used for a ceramic laminated capacitor produced by firing at the same time as an internal electrode material made of a base metal. The present invention relates to a body porcelain composition.

[0002]

2. Description of the Related Art Heretofore, a porcelain multilayer capacitor using a ceramic material mainly composed of calcium titanate, strontium titanate or lead titanate as a dielectric and an Ag-Pd-based or Pt-based alloy as an internal electrode has been known to be high in performance. It has been widely used in various consumer and industrial electronic circuits that require reliability. In order to manufacture a porcelain multilayer capacitor, for example, a thickness of 30 to
A 50 μm porcelain green sheet is produced by the doctor blade method, etc., and a metal conductor layer to be an internal electrode is formed on this porcelain green sheet. Was fired in a natural atmosphere at a high temperature of, for example, 1200 ° C. or higher to produce a sintered body, and an external extraction electrode electrically connected to the internal electrode was baked on the end surface of the sintered body.

[0003]

In the conventional porcelain multilayer capacitor, it was necessary to satisfy the following two conditions as the material of the internal electrodes. Firstly, since the dielectric ceramic material and the internal electrode material are simultaneously fired, they have a melting point higher than the sintering temperature of the dielectric ceramic material. Secondly, they are oxidized even in an oxidizing high temperature atmosphere. And does not react with the dielectric. There are noble metals such as platinum, gold, palladium and their alloys as the electrode materials that satisfy such conditions, and these noble metals have been mainly used as the internal electrode materials of the porcelain multilayer capacitors. However, although these electrode materials have excellent characteristics, they are expensive, and therefore, the electrode material cost in 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
Although there are base metals such as i, Fe, Co, and Cu, in recent years, the demand for high-frequency compatibility for electronic components has increased, and it has become necessary to use an internal electrode of a porcelain multilayer capacitor having high conductivity and low equivalent series resistance. 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 lose their role as electrodes. Therefore, in order to use these base metals for the internal electrodes of the porcelain monolithic capacitor, it is necessary to fire them together with the dielectric porcelain material in a neutral or reducing atmosphere.

However, the conventional dielectric ceramic material has a drawback in that it is remarkably reduced when it is fired in such a reducing atmosphere 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 that is easily oxidized and has a low melting point, such as Cu or a Cu-based alloy, is used as the internal electrode of the multilayer capacitor, a dielectric material having excellent reduction resistance and sintering at low temperature is required. It is.

Therefore, the main object of the present invention is to
It is an object of the present invention to provide a non-reducing dielectric ceramic composition which does not deteriorate in electrical characteristics even if it is sintered at a low temperature of 080 ° C. or lower and is fired in a reducing atmosphere.

[0008]

The present invention has a general formula of A (Bi ₂ O ₃ .BTiO ₂ ) + (100-A) {(S
r _100-XY Pb _X Ca _Y ) TiO ₃ } (however, A,
B, X and Y are represented by mol%), and A, B, X and Y are respectively represented by Are represented by the following general formula: aLi ₂ O + bRO + cB ₂ O ₃ + (100-ab−
c) SiO ₂ (where R is Mg, Ca, Sr and B
at least one selected from a, a, b and c
Is represented by mol%), and a, b and c are respectively It is a non-reducing dielectric ceramic composition containing 0.1 to 30% by weight of the subcomponent of

[0009]

EFFECTS OF THE INVENTION The non-reducing dielectric ceramic composition according to the present invention is excellent in 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,
Dielectric loss is less than 5% and excellent in sinterability,
It 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 material for a porcelain multilayer capacitor, C is used as an internal electrode material
u or Cu-based alloy can be used. for that reason,
It is possible to obtain a ceramic laminated capacitor that is less expensive and has a smaller equivalent series resistance than those using a conventional noble metal.

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

[0011]

EXAMPLE SrC, an industrial material, was used as a starting material.
O ₃ , CaCO ₃ , Pb ₃ O ₄ , Bi ₂ O ₃ , TiO ₂
And so on. These raw materials were weighed so as to have the compositions shown in Tables 1 and 2 , wet-mixed in a ball mill for 16 hours, and then evaporated to dryness to obtain a mixed powder. The obtained mixed powder was put in a zirconia box and calcined at 900 ° C. for 2 hours to obtain a predetermined compound.

Next, the compound thus obtained was coarsely pulverized so as to pass through a 200-mesh sieve.
Sample Nos. 1 to 26 shown in Table 2 and Sample No. 27 shown in Table 2
It was compounded so that each desired compounding ratio of the dielectric material in ~ 33.

[0013]

[Table 1]

[Table 2]

Further, as an auxiliary component, a reduction inhibitor having an excellent effect of preventing reduction of the dielectric ceramic when firing in a reducing atmosphere, for example, sample numbers 34 to 59 shown in Table 3 and sample number 60 shown in Table 4. In order to obtain the reduction inhibitor in .about.66 , oxides, carbonates or hydroxides of the respective components were mixed, wet mixed and pulverized with a ball mill for 16 hours, and then evaporated to dryness 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 was roughly crushed so as to pass through a 200-mesh sieve to prepare a reduction inhibitor.

[0015]

[Table 3]

[Table 4]

Next, a reduction inhibitor was added to the above dielectric material at a ratio shown in Tables 1 to 4. In this case, in the sample numbers 1-26 of Table 1 and the sample numbers 27-33 of Table 2,
5Li ₂ O + 20BaO + 15Ca as a reduction inhibitor
O + 5SrO + 5MgO + 25B ₂ O ₃ + 25SiO ₂
(Mol%) of a reduction inhibitor was added. Further, Sample No. 60 to 66 of the sample No. 34-59 and Table 4 in Table 3,
98 (Sr ₅₀ Pb ₂₀ Ca ₃₀ ) TiO 2 as a dielectric material
A dielectric material of ₃ + 2 (Bi ₂ O ₃ .2TiO ₃ ) (mol%) was used.

A polyvinyl butyral type binder and an organic solvent were added thereto, wet mixed in a ball mill for 16 hours, and formed into a sheet by a doctor blade method to obtain a green sheet. After drying this green sheet, it was cut into an appropriate size, a Cu electrode paste was printed on the cut green sheet by a screen printing method, and a predetermined number of the sheets were stacked and thermocompression bonded 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. This raw unit was placed in an electric furnace adjusted to a reducing atmosphere in which Cu electrodes were not oxidized using a mixed gas of N ₂ , H ₂ and H ₂ O, and fired at 920 to 1080 ° C. for 2 hours to obtain a porcelain multilayer capacitor. Was.

The obtained porcelain multilayer capacitor was immersed in a wiping solution and a sintering degree test was conducted to determine the optimum firing temperature. Further, 1 kHz, 1 Vrm at a temperature of 25 ° C.
The electrical properties of the dielectric constant ε, the dielectric loss tan δ, and the insulation resistance at s were measured. Table 1 Sample No. 1 to 26, the sample numbers in Table 2 27 to 33 and sample number 34 to 59 of Table 3,
The optimum firing temperatures and electrical characteristics of sample numbers 60 to 66 in Table 4 are shown in Tables 5 and 6, and Tables 7 and 8, respectively.

[0019]

[Table 5]

[Table 6]

[0020]

[Table 7]

[Table 8]

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. As shown in Sample No. 1 in Table 1, the amount of the reduction inhibitor added was 0.1% by weight.
If it is less than 1, the dielectric is reduced, the dielectric loss tan δ becomes 5% or more, and the insulation resistance deteriorates. As shown in sample numbers 8 and 9 of Table 1, the value of A, that is, Bi ₂ O ₃
If it exceeds 10 mol%, it reacts with Cu as an internal electrode and causes electrode breakage, which is not preferable as a multilayer capacitor. As shown in sample numbers 11 and 12 in Table 1, B
When the value of TiO ₂ is less than 0.8 or the value of B exceeds 8 as shown in Sample Nos. 16 and 17, the insulation resistance is less than 10 ¹⁰ Ωcm even when 30% by weight of the reduction inhibitor is added. It is not preferable. As shown in Sample No. 26 of Table 1 and Sample Nos. 27, 28, 30, 31, 33 of Table 2, when the value of Y exceeds 70 mol%, the insulation resistance is 10 ¹⁰ even if the reducing inhibitor is added. It is not preferable because it is smaller than Ωcm.

Next, the reason why the reduction inhibitor as a subcomponent is limited will be described. Sample Nos. 47 and 48 in Table 3
49 and 50, when the value of b, that is, RO is less than 10 mol%, the insulation resistance becomes less than 10 ¹⁰ Ωcm, which is not preferable. Sample No. 39, 40, 4 in Table 3
As shown in FIGS. 1 and 42, when the value of b, that is, RO becomes 55 mol% or more, the firing temperature becomes 1080 ° C. or more, and C
The u internal electrode elutes and cannot be used as a capacitor. As shown in Sample No. 55 of Table 3, the value of a, that is, Li ₂ O is 20 mol% or more, or Sample No. 57
As shown in FIG. 5, when the value of c, that is, B ₂ O ₃ is 40 mol% or more, the dielectric properties are significantly impaired, or the metal is softened and deformed before the completion of sintering. Sample No. 34 in Table 3,
As shown in 35, the addition amount of the reduction inhibitor was 0.1% by weight.
When it is less than the above range, the dielectric is reduced and the insulation resistance is deteriorated.
Further, as shown in Sample No. 66 of Table 4, when the addition amount of the reduction inhibitor exceeded 30% by weight, the dielectric porcelain softened,
Further deformation is not preferred.

In the above-mentioned examples, as the anti-reducing agent, a mixture was added in a predetermined proportion to the main component, which was previously mixed in a predetermined ratio, heat-treated at a high temperature, melted, crushed and vitrified. However, as a method of adding the reduction inhibitor,
A powder which has been previously blended 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 of a dielectric material containing bismuth oxide and at least one of lead oxide, calcium titanate, and strontium titanate and a Cu-based internal electrode material, the dielectric material is reduced. It is necessary to keep the internal electrode in an oxygen atmosphere in which the internal electrode is not oxidized. That is, when the dielectric is reduced, the insulation resistance is reduced, and when the internal electrodes are oxidized, the equivalent series resistance is increased, which causes problems such as loss of the function of the capacitor.

On the other hand, according to the present invention, by adding the reduction inhibitor to the dielectric material, the oxygen partial pressure of the calcinable atmosphere spreads particularly to the low oxygen partial pressure side, so that the oxygen partial pressure is strictly controlled. It is possible to obtain a product with a high non-defective rate in an appropriate reducing atmosphere without controlling. 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 composed of such a composition does not deteriorate the dielectric characteristics and insulation resistance,
The specific resistance is 10 ¹⁰ Ωcm or more, and the dielectric loss thereof is 5% or less. Furthermore, the firing temperature of the non-reducing dielectric ceramic composition according to the present invention is 1080 ° C. or lower. Therefore, if the non-reducing dielectric ceramic composition according to the present invention is used as a material for a multilayer capacitor, Cu or a Cu-based alloy can be used as a material for internal electrodes. Thereby, the conventional Pd-Ag or Pd-Ag
Compared with the case of using a t-based noble metal electrode, the cost can be significantly reduced, and a multilayer ceramic capacitor having a small equivalent series resistance can be obtained.

Claims (1)

(57) [Claims] 1. The general formula is A (Bi ₂ O ₃ .BTiO ₂ ) + (100-A) {(S
r _100-XY Pb _X Ca _Y ) TiO ₃ } (however, A,
B, X and Y are represented by mol%), and A, B, X and Y are respectively represented by The main formula in the range of is represented by the following general formula: aLi ₂ O + bRO + cB ₂ O ₃ + (100-ab−
c) SiO ₂ (where R is Mg, Ca, Sr and B
at least one selected from a, a, b and c
Is represented by mol%), and a, b and c are respectively A non-reducing dielectric porcelain composition containing 0.1 to 30% by weight of the sub-component.