JPH05238820A - Non-reductive dielectric porcelain composition - Google Patents

Abstract

PURPOSE:To obtain a non-reductive dielectric porcelain composition capable of being sintered without change in its tissue into a semiconductor even under low oxygen partial pressure, having a dielectric constant of >=3000, an insulation resistance of >=11.0 by log IR, and a temperature characteristic of dielectric constant of + or -15% at -55 deg.C to 125 deg.C based on the value of the capacity at 25 deg.C as a standard. CONSTITUTION:The non-reductive dielectric porcelain composition comprises 100mol.% of a main component comprising 88.0-99.0mol.% of BaTiO3, 0.5-6.0mol% of SnO2 and 0.5-6.0mol% of NiO and having an alkali metal oxide content of <=0.04wt.% as an impurity, auxiliary components comprising 0.2-4.0mol.% of Ba, 0.3-3.0mol.% of Mn and 0.5-5.0mol.% of MgO, and 0.5-2.5mol.% of oxide glass consisting mainly of BaO-SrO-Li2O-SiO2.

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 in particular, a non-reducing dielectric porcelain used as a dielectric material such as a laminated capacitor having a base metal such as nickel as an internal electrode material. It relates to a composition.

[0002]

2. Description of the Related Art BaTiO ₃ -based dielectric ceramic materials are widely used in various applications including multilayer capacitors because they have excellent dielectric properties.

The conventional BaTiO ₃ -based dielectric ceramic material has the property of being reduced to a semiconductor when it is fired under a neutral or reducing low oxygen partial pressure. Therefore, the internal electrode material of the multilayer capacitor does not melt at the temperature at which the dielectric ceramic material is sintered, and is not oxidized even if fired under a high oxygen partial pressure that does not turn the dielectric ceramic material into a semiconductor, such as Pd, Pt. Had to use precious metals such as. This has been a major obstacle to cost reduction of manufactured multilayer capacitors.

Therefore, in order to solve the above problems,
For example, it has been desired to use a base metal such as Ni as a material for the internal electrodes. However, when such a base metal is used as a material for the internal electrode and fired under the conventional conditions, the electrode material is oxidized and does not function as an electrode. Therefore, in order to use such a base metal as a material for the internal electrode, even if it is fired under a neutral or reducing low oxygen partial pressure, it does not become a semiconductor and has a high ratio required as a dielectric material for a capacitor. There has been a need for a dielectric porcelain material having resistance and excellent dielectric properties. As a dielectric ceramic material satisfying these conditions, for example, BaTiO ₃ —CaZrO ₃ disclosed in JP-A-62-256422.
-MnO-MgO system composition, Japanese Patent Publication No. 61-14611
BaTiO of No. _{3 - (Mg, Zn, Sr} , Ca) O-B
Compositions based on ₂ O ₃ —SiO ₂ have been proposed.

[0005]

However, the BaTiO _3- disclosed in JP-A-62-256422 is disclosed.
In the CaZrO ₃ —MnO—MgO-based non-reducing dielectric ceramic composition, CaZrO ₃ or CaT generated in the firing process is used.
Since iO ₃ easily forms a secondary phase together with Mn and the like, there is a risk that reliability may be deteriorated at high temperatures.

Also, BaTiO _3- (Mg, Zn, Sr, Ca) O disclosed in Japanese Patent Publication No. 61-14611.
The non-reducing dielectric ceramic composition of the type —B ₂ O ₃ —SiO ₂ has a dielectric constant of 2000 to 2800 of the obtained dielectric and is a conventional ceramic composition using a noble metal such as Pd. It was inferior to the dielectric constant of 3000 to 3500. Therefore, replacing the composition with the conventional material as it is for cost reduction is disadvantageous in terms of miniaturization and large capacity of the capacitor, and a problem remains.

Further, the temperature change rate (TCC) of the dielectric constant of this composition is -25 ° C with reference to the capacitance value of 20 ° C.
± 85% in the temperature range from + 85 ° C to + 85 ° C
At a high temperature exceeding ℃, it exceeds 10%, and E
There is a drawback that the X7R characteristic defined by IA is also largely deviated.

Therefore, the main object of the present invention is that even under a low oxygen partial pressure, the structure can be fired without becoming a semiconductor, the dielectric constant is 3000 or more, and the insulation resistance is logI.
R is 11.0 or more, and the temperature characteristic of the dielectric constant is
It is to provide a non-reducing dielectric porcelain composition that satisfies the range of ± 15% over a wide range of -55 ° C to 125 ° C based on the capacitance value of 25 ° C.

[0009]

According to the present invention, the compounding ratio of BaTiO _3, which has an alkali metal oxide content of 0.04% by weight or less as an impurity, SnO ₂ , and NiO is BaTiO ₃ 88. 0.0 to 99.0 mol% and Sn
And O ₂ 0.5 to 6.0 mol%, relative to 100 mol of the main ingredient% that ranges between NiO0.5~6.0 mol%, as an auxiliary component, and BaO0.2~4.0 mol% , MnO0.
3 to 3.0 mol% and 0.5 to 5.0 mol% MgO, and 100 parts by weight of the above components, and BaO
The oxide glass mainly comprising -SrO-Li ₂ O-SiO ₂ containing 0.5 to 2.5 parts by weight, a non-reducing dielectric ceramic composition.

[0010]

The non-reducing dielectric ceramic composition according to the present invention is 1260 to 1260 in a neutral or reducing atmosphere.
Even if it is fired at a temperature of 1300 ° C., the structure is not reduced to be a semiconductor. Further, this non-reducing dielectric ceramic composition exhibits a high insulation resistance value of 11.0 or more in log IR, a high dielectric constant of 3000 or more, and a capacitance temperature change rate defined by EIA as X7R characteristics. To be satisfied.

Therefore, when the non-reducing dielectric ceramic composition according to the present invention is used as a dielectric material of a laminated ceramic capacitor, a base metal material represented by Ni or the like can be used as an internal electrode material. Therefore, compared with the conventional one using a noble metal such as Pd, it is possible to significantly reduce the cost without deteriorating the characteristics.

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

[0013]

[Example] As a starting material, BaTiO ₃ , BaC having different contents of alkali metal oxides contained as impurities
O ₃ , SnO ₂ , NiO, MnO, MgO and oxide glass were prepared. These raw materials were weighed so that the composition ratios shown in Table 1 were obtained to obtain weighed products. Sample numbers 1 to
For No. 27, the content of alkali metal oxide is 0.0
3 using BaTiO ₃ weight%, for Sample No. 28, the content of alkali metal oxides using BaTiO ₃ of 0.05 wt%, the sample No. 29, the content of alkali metal oxide 0.07 wt% BaTiO
₃ was used.

[0014]

[Table 1]

After adding 5% by weight of a vinyl acetate binder to the obtained weighed product, it was sufficiently wet-mixed by a ball mill using PSZ balls. Next, the dispersion medium in this mixture was evaporated and dried, and then a powder was obtained through a step of sizing. The obtained powder was treated at a pressure of ² ton / cm ² with a diameter of 10 mm,
A 1 mm thick disc was press-molded to obtain a molded body.

Next, the thus obtained molded body is debindered in air at 400 ° C. for 3 hours, and then the H ₂ / N ₂ volume ratio is 3/100.
2 in the reducing atmosphere gas stream at the temperature shown in Table 2.
It was fired for an hour to obtain porcelain.

[0017]

[Table 2]

Silver paste was applied to both surfaces of the obtained porcelain and baked to form silver electrodes, thereby obtaining a capacitor. Then, the dielectric constant ε, the dielectric loss tan δ, the insulation resistance value (logIR) of this capacitor at room temperature.
And the rate of temperature change of capacity (TCC) were measured. The results are summarized in Table 2.

The dielectric constant ε and the dielectric loss tan δ were measured under the conditions of a temperature of 25 ° C., a frequency of 1 kHz and an AC voltage of 1V. Also, regarding the insulation resistance value, the temperature is 25
The result after pre-application of the DC voltage of 500 V for 2 minutes at 0 ° C. is shown in logarithmic value (logIR). Furthermore, regarding the temperature change rate (TCC), the change rate (ΔC ₋₅₅ / C at −55 ° C. and 125 ° C. when the capacitance value at 25 ° C. is used as a reference.
₂₅ , ΔC ₊₁₂₅ / C ₂₅ ) and between −55 ° C. and + 125 ° C., the absolute value of the value at which the capacity temperature change rate is maximum, that is, the maximum change rate (| ΔC / C ₂₅ | _max ) is shown.

As is clear from Table 2, the non-reducing dielectric ceramic composition according to the present invention exhibits excellent characteristics.

The reason for limiting the ranges of the main component and the subcomponents in the present invention as described above is as follows.

First, the reason for limiting the range of the main component will be described.

The composition ratio of the main component BaTiO ₃ is 8
The composition ratio of 8.0 to 99.0 mol% is 88.
If it is less than 0 mol%, the composition ratio of SnO ₂ and NiO increases, and as shown in Sample No. 5, the insulation resistance and the dielectric constant decrease, which is not preferable. Also, Ba
When the composition ratio of TiO ₃ exceeds 99.0 mol%, there is no effect of addition of SnO ₂ and NiO, and as shown in Sample No. 3, the rate of change in capacity and temperature at high temperatures near the Curie point is large (+ ) Side is not preferable. Further, the content of the alkali metal oxide in BaTiO ₃ is set to 0.04% or less. When it exceeds 0.04%, as shown in sample numbers 28 and 29, the dielectric constant lowers, which is not practical. It is not preferable.

Further, the SnO ₂ content is set to 0.5 to 6.0 mol%, when the content is less than 0.5 mol%, the dielectric constant is lowered as shown in Sample No. 3. At the same time, the rate of change of the capacity temperature in the low temperature portion deviates to the (−) side, which is not preferable. Further, if the content exceeds 6.0 mol%, as shown in Sample Nos. 5 and 6, the rate of change in capacity-temperature at high temperature shifts to the (+) side, which is not preferable.

The NiO content is set to 0.5 to 6.0 mol% when the content is less than 0.5 mol%, as shown in Sample No. 3, the capacity-temperature change rate at high temperature. Shifts to the (+) side, which is not preferable. Further, when the content exceeds 6.0 mol%, as shown in Sample Nos. 5 and 7, the dielectric constant is lowered and the rate of change in capacity temperature at the low temperature portion is shifted to the (−) side, which is preferable. Absent.

Next, the reason for limiting the range of subcomponents will be described.

The amount of BaO added is set to 0.2 to 4.0 mol%, when the added amount is less than 0.2 mol%, as shown in sample No. 10, the structure becomes semi-conductive during firing. However, it is not preferable because it causes a significant decrease in insulation resistance. Also,
If the addition amount exceeds 4.0 mol%, sample number 13
As shown in, the sinterability is reduced, which is not preferable.

The amount of MnO added is set to 0.3 to 3.0 mol% if the added amount is less than 0.3 mol%.
As shown in Sample No. 18, the effect of improving the reduction resistance of the structure is lost and the insulation resistance value is remarkably lowered, which is not preferable. On the other hand, if the addition amount exceeds 3.0 mol%, the insulation resistance value will decrease as shown in Sample No. 16, which is not preferable.

The amount of MgO added is set to 0.5 to 5.0 mol%. When the added amount is less than 0.5 mol%, as shown in Sample No. 20, the curve of the rate of change in capacity-temperature is calculated. It is not preferable because there is no flattening effect, there is a tendency to deviate to the (-) side especially at low temperatures, and the effect of improving the insulation resistance value disappears. On the other hand, if the addition amount exceeds 5.0 mol%, as shown in Sample No. 23, the dielectric constant ε and the insulation resistance value decrease, which is not preferable.

[0030] _{Finally, BaO-SrO-Li 2 O} -Si
The addition amount of the oxide glass containing O ₂ as a main component is 0.5 to
The reason why the amount is 2.5% by weight is that when the amount added is less than 0.5% by weight, the effect of lowering the sintering temperature and the effect of improving the reduction resistance are lost as shown in Sample No. Not preferable. On the other hand, if the addition amount exceeds 2.5% by weight, as shown in sample No. 27, the dielectric constant ε decreases, which is not preferable.

The characteristic data shown in Table 2 are the data obtained for the single plate capacitor, but even for the laminated capacitor in which the same composition is sheet-formed and chip-processed, it is almost the same as the present data. The result is obtained.

Claims (1)

[Claims] 1. BaTiO ₃ having an alkali metal oxide content of 0.04% by weight or less as an impurity and S.
The compounding ratio of nO ₂ and NiO is within the range of BaTiO ₃ 88.0 to 99.0 mol%, SnO ₂ 0.5 to 6.0 mol%, and NiO 0.5 to 6.0 mol%. BaO 0.2 to 4.0 mol%, MnO 0.3 to 3.0 mol%, and MgO 0.5 to 5.0 mol% are contained as accessory components with respect to a certain main component 100 mol%. Furthermore, if the above components are taken as 100 parts by weight, Ba
O-SrO-Li a ₂ O-SiO ₂ oxide glass mainly containing 0.5 to 2.5 parts by weight, non-reducible dielectric ceramic composition.