JP3064571B2 - 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 dielectric porcelain composition, and more particularly to a dielectric porcelain composition used as a material for a multilayer ceramic capacitor, for example.

[0002]

2. Description of the Related Art Multilayer ceramic capacitors have advantages such as small size and large capacity, excellent high frequency characteristics, excellent heat resistance, and high mass productivity. Therefore, it meets the requirements of industrial electronic equipment and consumer electronic equipment such as light and thin, small, high quality, and high frequency design, and in recent years the demand has been steadily increasing.

In conventional multilayer ceramic capacitors, expensive noble metals such as Au, Pt, and Pd were generally used as internal electrodes.

[0004]

However, Au,
In the case of a multilayer ceramic capacitor using an expensive noble metal such as Pt or Pd as an internal electrode, the ratio of the electrode material cost to the production cost is large, so that there is a limit in reducing the overall cost.

For this reason, a glass component composed of an oxide such as B, Bi, or Pb is added to a high dielectric constant porcelain composition mainly composed of BaTiO ₃ , and the firing temperature is set to 1300 to 135.
Multilayer ceramic capacitors have been developed in which the temperature is reduced from 0 ° C. to 1100 ° C. to 1150 ° C. Since this multilayer ceramic capacitor can be sintered at a low temperature, a relatively inexpensive Ag is used.
-A Pd-based alloy can be used as the internal electrode.

However, in this multilayer ceramic capacitor, BaTiO ₃ is added by adding a glass component.
There is a disadvantage that the intrinsic dielectric constant of the base composition is reduced. As a result, the dimensions of the multilayer ceramic capacitor are increased, and the cost of the electrode material is reduced.

Therefore, a main object of the present invention is to provide a dielectric porcelain composition which can obtain a porcelain having a dielectric constant of 10,000 or more and has a firing temperature of 1000 ° C. or less.

[0008]

SUMMARY OF THE INVENTION The present invention relates to Pb (Mg
_1/3 Nb _2/3 ) O ₃ , PbTiO ₃ and Pb (Ni
The mixing ratio of _1/3 Nb _2/3 ) O ₃ to Pb (Zn _1/2 W _1/2 ) O ₃ is Pb (Mg _1/3 Nb _2/3 ) O ₃ 4.0
93.0 mol%, PbTiO ₃ 1.5 to 35.0 mol%, and Pb (Ni _1/3 Nb _2/3 ) O ₃ 1.5 to 5
1.0 mol% and Pb (Zn _1/2 W _1/2 ) O ₃ 1.0
100 mol% of the main component in the range of 〜34.0 mol%
On the other hand, as a sub-component, the main component was 100 parts by weight,
The dielectric porcelain composition contains 0.1 to 10.0 parts by weight of Zn in terms of ZnO.

Further, it is preferable that Mn is contained in an amount of 0.5 part by weight or less in terms of MnO ₂ with the main component being 100 parts by weight as a subcomponent.

[0010]

The porcelain obtained by the dielectric porcelain composition according to the present invention has a dielectric constant of 10,000 or more, a dielectric loss of 2.5% or less, and a specific resistance at room temperature of 10 ¹² Ω ·.
cm or more, and the temperature change rate of the capacitance is −25 ° C. to +
JIS standard E characteristic (−25 ° C to +
At 85 ° C., ΔC / C ₂₀ = + 20% to −55%). Further, the dielectric porcelain composition according to the present invention has the following properties:
It can be fired at a low temperature of 000 ° C or less.

Therefore, the dielectric ceramic composition according to the present invention can be used as a dielectric material for not only general ceramic capacitors but also multilayer ceramic capacitors. In particular, since the firing temperature is low, an Ag-Pd alloy can be used as an internal electrode when manufacturing a multilayer ceramic capacitor, and a small-sized and large-capacity capacitor can be industrially produced.

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

[0013]

[Example] First, as starting materials, having a purity of 99.9% or more of _{PbO, NiO, Nb 2 O 5} , TiO 2, ZnO, W
O ₃ , MgO and MnO ₂ were prepared. These raw materials were weighed so as to obtain a dielectric ceramic composition having a composition ratio shown in Table 1 to obtain a weighed material.

[0014]

[Table 1]

[0015] 100 g of each of these weighed materials was put into a polyethylene pot together with an agate, and wet-mixed for 10 hours to obtain a mixture slurry. The mixture slurry is dehydrated, dried, and placed in an alumina box, and is heated at 650 ° C to 80 ° C.
The mixture was kept at 0 ° C. for 2 hours and calcined to obtain a calcined powder (primary reaction powder). The calcined powder was coarsely pulverized in advance, 3 wt% of polyvinyl alcohol was added as a binder, and wet mixing was performed again to obtain a slurry. After the slurry was dried, it was passed through a 60-mesh sieve to obtain a sized granule for molding. Further, a disc having a diameter of 1.0 cm and a thickness of 1.0 mm was formed at a pressure of 2000 kg / cm ² by an oil press to obtain a disc.

The obtained disc was placed in an alumina box made of zirconia powder as a powder, heated at 400 ° C. for 4 hours to burn the organic binder, and then fired at the firing temperature shown in Table 2 for 2 hours. After firing, a porcelain disk was obtained. A silver paste containing a lead borosilicate glass slit was applied to both surfaces of the obtained porcelain disk, and baked at 750 ° C. for 10 minutes to form electrodes, which were used as measurement samples.

For each sample, the capacitance (C) and the dielectric loss (tan δ) were measured at a temperature of 25 ° C., 1 KHz, and 1 Vrm.
The measurement was performed under the condition of s. The value of the insulation resistance (IR) was measured when a voltage of DC 500 V was applied for 2 minutes. Further, the thickness of the sample and the diameter of the electrode were measured, and the dielectric constant (ε) and the specific resistance (ρ) were calculated.

The test results are shown in Table 2 together with the firing temperature of each sample.

[0019]

[Table 2]

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

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

For Pb (Mg _1/3 Nb _2/3 ) O ₃ ,
The reason for setting the range to 4.0 to 93.0 mol% is that as shown in Sample No. 1, when the dielectric constant is less than 4.0 mol%, the dielectric constant is 100%.
With a value of less than 00, the dielectric loss exceeds 2.5%. Further, as in the case of Sample No. 10, when it exceeds 93.0 mol%, the dielectric constant increases, but the temperature characteristic does not satisfy the E characteristic.

The range of PbTiO ₃ is 1.5
The reason why the content was set to ３５35.0 mol% is as shown in sample number 5,
If it is less than 1.5 mol%, the dielectric constant will decrease significantly, and the dielectric constant will be less than 10,000. Also, as in Sample No. 6, when it exceeds 35.0 mol%, the dielectric loss exceeds 2.5%.

For Pb (Ni _1/3 Nb _2/3 ) O ₃ ,
The reason why the range is set to 1.5 to 51.0 mol% is that, as shown in Sample No. 12, when it is less than 1.5 mol%, the dielectric constant becomes high, but the temperature characteristic does not satisfy the E characteristic. Further, as in Sample No. 16, if it exceeds 51.0 mol%, the dielectric constant becomes less than 10,000.

With respect to Pb (Zn _1/2 W _1/2 ) O ₃ , the range was set to 1.0 to 34.0 mol%. Sintering temperature is 10
Exceeding 00 ° C and permitting less than 10,000. Also,
As in the case of Sample No. 18, when the content exceeds 34.0 mol%, the sintering temperature is lowered, but the dielectric constant becomes less than 10,000 and the specific resistance does not reach 10 ¹² Ω · cm at room temperature.

Next, the reasons for limiting the range of the subcomponent will be described.

Converting Zn to ZnO is 0.1 to 10.0
The weight part is, as shown in sample No. 19, when less than 0.1 part by weight, the dielectric constant is less than 10,000. If the amount exceeds 10.0 parts by weight as in sample No. 20, the temperature characteristic does not satisfy the E characteristic, and the specific resistance does not reach 10 ¹² Ω · cm.

The reason why Mn was converted to MnO ₂ and 0.5 parts by weight or less was that the IR at room temperature and at high temperature both increased to 10 ¹² Ω · cm within this range. If the amount exceeds 0.5 parts by weight, the specific resistance does not reach 10 ¹² Ω · cm at room temperature.

As is clear from Table 2, the dielectric ceramic compositions according to the present invention have a high dielectric constant of 10,000 or more. Moreover, despite the high dielectric constant, the temperature change rate of the capacitance satisfies the E characteristic. Further, the dielectric loss is as low as 2.5% or less, and the sintering temperature is as low as 1000 ° C. or less.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI C04B 35/495 C04B 35/46 H // H01G 4/12 358 35/00 J (72) Inventor Yukio Sakabe Nagaokakyo, Kyoto Prefecture 2-26-10 Ichitenjin Murata Manufacturing Co., Ltd. (56) References JP-A-3-54144 (JP, A) JP-A-62-115608 (JP, A) JP-A-58-161972 (JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) H01B 3/00-3/14 C04B 35/00-35/51

Claims (2)

(57) [Claims] 1. Pb (Mg _1/3 Nb _2/3 ) O ₃ , PbT
iO ₃ , Pb (Ni _1/3 Nb _2/3 ) O ₃ and Pb (Z
n _1/2 W _1/2 ) O _{3 has} a mixing ratio of Pb (Mg _1/3 Nb _2/3 ) O ₃ 4.0 to 93.0 mol%, and PbTiO ₃ 1.5 to 35.0 mol%. Pb (Ni _1/3 Nb _2/3 ) O ₃ 1.5 to 51.0 mol%, and Pb (Zn _1/2 W _1/2 ) O ₃ 1.0 to ₃
With respect to 100 mol% of the main component within the range of 4.0 mol%, as the sub-component, 100 parts by weight of the main component and Zn
0.1 to 10.0 parts by weight in terms of ZnO,
Dielectric porcelain composition. 2. The dielectric ceramic composition according to claim 1, wherein Mn is contained in an amount of 0.5 part by weight or less in terms of MnO ₂ , based on 100 parts by weight of the main component as a subcomponent.