JP2540029B2 - Semiconductor porcelain composition - Google Patents

Description

TECHNICAL FIELD The present invention relates to a SrTiO ₃ —Y ₂ O ₃ —Nb ₂ O ₅ based porcelain composition suitable for a semiconductor ceramic capacitor, particularly a grain boundary insulation type semiconductor ceramic capacitor. .

[Conventional technology]

Conventional semiconductor porcelain capacitors are classified into surface layer types such as reduction / reoxidation type and weir layer capacitance type, and grain boundary layer types are roughly classified into grain boundary insulating types.

However, the medium grain boundary insulation type of these various semiconductor porcelain capacitors does not have a larger capacity than the weir layer capacity type, and has a lower withstand voltage than the reduction / reoxidation type. The weir layer capacitive type has poor frequency characteristics and a large dielectric loss tan δ,
Withstand voltage is small. The reductive reoxidation type has poor frequency characteristics, large temperature characteristics, and large dielectric loss tan δ. There were drawbacks.

[Problems to be solved by the invention]

As described above, the various conventional semiconductor ceramic capacitors have various drawbacks.

The present invention is intended to obtain a semiconductor ceramic composition, particularly a grain boundary insulation type semiconductor ceramic capacitor, which has a high dielectric constant, good frequency characteristics and temperature characteristics, and a small dielectric loss tan δ. . MnO
Is added, a semiconductor porcelain composition having a high insulation resistance can be added, and by addition of SiO ₂ , the appropriate range of the SrO / TiO ₂ ratio can be expanded.

[Means for solving problems]

The present invention provides a semiconductor porcelain composition having (100-xy)
・ SrTiO ₃ as a main component and x ・ Y ₂ O ₃ and y as secondary components
· Nb ₂ O _5, respectively, characterized in that it contains 0.1~0.4mol% (100-x-y ) · SrTiO 3 + x · Y 2 O 3 + y · Nb 2 O 5 system using the semiconductor ceramic composition.

In addition, converting manganese to MnO for the above main components
A semiconductor porcelain composition characterized by containing 0.02 to 0.2 mol% and further containing 0.01 to 0.1 mol% of SiO ₂ with respect to the above main component can be used.

〔Example〕

Using SrCO ₃ , TiO ₂ , MnCO ₃ and SiO ₂ as starting materials and Y ₂ O ₃ and Nb ₂ O ₅ as semiconducting agents, weigh them so that the blending composition ratio shown in Table 1 or 2 is obtained. In a synthetic resin ball mill, water and boulders are added to these raw material mixtures, and wet mixing and stirring are performed for 20 hours. Then, it was dehydrated and dried, and calcined at 1200 ° C. and a rising / lowering temperature of 200 ° C./hr for 2 hours for stabilization to cause a chemical reaction. Add water and boulders again in a ball mill and crush and mix for 16 hours. This is dehydrated and dried, PVA is added as an organic binder of 2% by weight, and granulated and sized to obtain granule powder, and the powder is molded into a disk shape of 10φ × 0.5tmm at a molding pressure of about 3 ton / cm ^2. . This molded product was debindered at 800 ° C for 1 hour, and it was removed in a reducing gas stream (H ₂ + N ₂ atmosphere) at 1450 ° C for about 2 times.
It is fired for a time to become a semiconductor. The semiconductor porcelain element thus obtained has a size of 8.5φ × 0.4tmm, and 3 mg of Bi ₂ O ₃ --CuO system frit paste was applied as a diffusing substance by screen printing on both sides of this, and this was heated at 1150 ° C. in air. It is fired for 2 hours to obtain a semiconductor porcelain having an insulating layer formed on a crystal grain boundary. Ag paste was baked on both surfaces of this porcelain element at about 800 ° C. to obtain a grain boundary insulation type semiconductor porcelain composition having electrodes formed thereon.

Tables 1 and 2 show the results of measuring the electrical characteristics of each sample thus obtained. Where permittivity ε _s
The dielectric loss tan δ was measured at a frequency of 1 KHz. The insulation resistance was measured at room temperature of 20 ° C by applying 50V.

As is clear from Table 1, in the range of the present invention, the dielectric constant ε _s is about 75,000 or more, the dielectric loss tan δ is 0.72% or less, and the DC breakdown voltage Eb is 450 volt / mm or more, which are extremely excellent values. Is. (Sample No.8,9,10,13,14,16,17,18,19,21,24,
(25 and 26 are samples within the range) Next, the reasons for limiting the composition ratio will be described.

Sample No. 1,2,3,7,11,23, which cannot obtain a high value of the dielectric constant ε _s by adding the additional components Y ₂ O ₃ and Nb ₂ O ₅ alone,
Further, the sample No. 3 which cannot obtain a high value even in the DC breakdown voltage Eb is 3.

Next, even in the combined addition of Y ₂ O ₃ and Nb ₂ O ₅ , each
If it is less than 1%, the dielectric constant ε _s of the samples No. 4, 5, 6, 12, 27 is low, and the DC breakdown voltage Eb of the samples No. 5, 6 is also low. Y ₂ O ₃ 0.4m
When it exceeds ol%, the dielectric constants ε _{s of} Sample Nos. 27, 28 and 29 become low. When Nb ₂ O ₅ exceeds 0.4 mol%, sample Nos. 6, 22, and 29 have low DC breakdown voltage Eb.

In samples (Nos. 14 to 20) confirmed to have the effect of adding MnO, the effect of increasing the insulation resistance IR is not remarkable when the content is less than 0.02 mol% (Samples Nos. 14 and 15). Sample No. 20 containing 0.3 mol% of MnO has poor dielectric constant ε _s and dielectric loss tan δ.

Table 2 shows the composition and electrical characteristics of the samples with different amounts of SiO ₂ and SrO / TiO ₂ ratio.

From Table ₂ , the proper range of SrO / TiO ₂ ratio according to the added amount of SiO ₂ is defined as dielectric constant ε _s (75,000 or more), dielectric loss tan δ (0.72% or less) and DC breakdown voltage Eb (450 volt / mm or more) Samples that satisfy the electrical characteristics are No. 31, 32, 35, 36, 39,
40,43,44,47,48.

That is, when the amount of SiO ₂ is 0 and 0.005 mol%, SrO / Ti
The O ₂ ratio is in the proper range of 0.999 to 1.001. SiO ₂ is 0.01
In the case of mol%, the SrO / TiO ₂ ratio is in the appropriate range of 0.998 to 1.002. Furthermore, when the amount of SiO ₂ is 0.05 to 0.10 mol%, SrO / T
The iO ₂ ratio is 0.997 to 1.003, which widens the appropriate range.

However, if the SiO ₂ content is 0.20 mol%, the dielectric constant ε _s
There is a problem in the miniaturization of the lower product in addition (Sample Nos. 50 and 51) SiO _2, a proper range of SrO / TiO ₂ ratio than those with no SiO ₂ addition, proper of SrO / TiO ₂ ratio SiO with the effect of expanding the range (from 0.002 to 0.004 or 0.006)
The addition amount range of ₂ is 0.01 mol% or more and 0.10 mol% or less.

〔The invention's effect〕

As described above, (100-xy) .SrTiO ₃ + x of the present invention
According to the Y ₂ O ₃ + y · Nb ₂ O ₅ based semiconductor porcelain composition, Y ₂ O ₃ and Nb ₂ O ₅ are added as a sub-component (0.1 ≦ x ≦ 0.4,0.
1 ≦ y ≦ 0.4), permittivity ε _s , DC breakdown voltage E
Since a semiconductor porcelain composition having a high b and ε _s · Eb product can be obtained, it is possible to downsize the porcelain element.
It became possible to manufacture 10 ⁵ PF with 8φ substrate. The frequency characteristics, temperature characteristics and dielectric loss are also good. Furthermore, by adding 0.02 to 0.2 mol% of MnO, a semiconductor porcelain composition with high insulation resistance was obtained. Again
Since the appropriate range of SrO / TiO ₂ ratio can be expanded by adding 0.01 to 0.1 mol% of SiO ₂ , the manufacturing work becomes easy, mass production is possible, and the manufacturing cost can be reduced, which is an industrial advantage. It's a lot.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kiyoshi Furukawa 1-13-1 Nihonbashi, Chuo-ku, Tokyo TEDK Corporation (72) Shinobu Fujiwara 1-13-1 Nihonbashi, Chuo-ku, Tokyo TEDK Incorporated (56) References JP-A-57-27001 (JP, A)

Claims (4)

(57) [Claims] [Claim 1] as a main component (100-x-y) · SrTiO 3,
X · Y ₂ O ₃ and y · Nb ₂ O ₅ each as an accessory component are 0.1 to
It is characterized by containing 0.4 mol% ((100-xy))
_{· SrTiO 3 + x · Y 2} O 3 + y · Nb 2 O 5 based semiconductor ceramic composition. 2. The semiconductor porcelain composition according to claim 1, which contains manganese in an amount of 0.02 to 0.2 mol% in terms of MnO with respect to the main component. 3. The SiO ₂ content of 0.01 to 0.1 mol% with respect to the main component described in claim 1 or 2.
The semiconductor porcelain composition according to the item. 4. Bi is unevenly distributed in a grain boundary of a semiconductor porcelain obtained by molding and sintering the composition comprising the main component and subcomponents as set forth in any one of claims 1 to 3. The semiconductor porcelain composition according to one item.