JPS637611A - Compound for semiconductor porcelain capacitor - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a composition for semiconductor stone capacitors, in particular, compositions containing strontium titanate as a main component and containing specific additives, such as dielectric constant, insulation resistance, etc. The present invention relates to a composition for a grain boundary insulated semiconductor ceramic capacitor soaked in

[Problems to be Solved by the Invention Strontium cotitanate (Sr Ti 03 ) based semiconductor ceramic capacitors have an apparent large relative permittivity, relatively small dielectric loss, and barium titanate (Ba T
It is widely used as a semiconductor ceramic capacitor because it has better temperature characteristics than the i 03 ) type semiconductor ceramic capacitor. From this point of view, various studies have been conducted on strontium titanate-based semiconductor ceramics or their ceramic compositions, such as JP-A-54-78494, JP-A-5G-26650, and JP-A-50-149.
961@The investigation described in the official bulletin etc. is proposed. These are mainly composed of strontium titanate, to which additives such as niobium pentoxide and manganese dioxide are added, and they fully satisfy the various properties required for capacitors, such as dielectric constant and insulation resistance. It wasn't.

Incidentally, in recent years, as devices have become smaller, capacitors with even larger capacities are desired. In order to increase the capacitance of a grain boundary insulated capacitor, it is necessary to increase the size of the crystal grains, and it is generally considered desirable to grow them to a size of 50μ1 or more.

However, as the crystal grains become larger, the ratio of the grain boundary layer per unit area decreases, and the formation of an insulating tank is insufficient, resulting in problems such as a low insulation resistance, although the apparent dielectric constant increases. Requires some ingenuity in insulation treatment.

SUMMARY OF THE INVENTION In view of these conventional problems, an object of the present invention is to provide a composition for a semiconductor ceramic capacitor that can produce a grain-boundary insulated capacitor with excellent dielectric constant, insulation resistance, etc.

Means for Solving Problem E] In accordance with the above purpose, the present inventors have conducted various studies on additives for growing crystal grains of strontium ditanate using niobium pentoxide as a semiconducting agent. It was discovered that a semiconductor stoneware composition to which a specific amount of cupric and/or bismuth trioxide was added caused crystal grains to grow. After sintering this porcelain composition, an insulating agent was applied to the porcelain surface, and the grain boundaries were It has been found that by thermally diffusing the layers, an excellent semiconductor ceramic capacitor with high dielectric constant and insulation resistance and low dielectric loss can be obtained, leading to the present invention.

That is, the present invention provides strontium oxide (SrQ) 10
Titanium dioxide (Ti 02 ) 99.0 to 0 mol
102.0 mol and niobium pentoxide (Nb20s) 0.02
For the main component consisting of ~1.00 mol, manganese dioxide (Mn 02 ) was added to o, +o ~i, oo -E/l/
Cupric oxide (CuO) 0.01-0.85 mol and/or bismuth trioxide (Bi203)
There is a composition for a semiconductor ceramic capacitor in which 0.01 to 0.50 mol is added.

In the present invention, as mentioned above, titanium dioxide is added to 99.0 to 10 moles of strontium oxide to 100 moles of strontium oxide.
2.0 mol and 0.0 niobium pentoxide as a semiconducting agent
2 to 1.00 mol of manganese dioxide is used as the main component of the semiconductor ceramic composition, and 0.10 to 1.00 of manganese dioxide is added to this as the main component of the semiconductor ceramic composition.
It is characterized by adding 0.01 to 0.85 mol of E/l/second oxide w4 and/or 0.01 to 0.50 mol of bismuth oxide.

In this composition, the amount of manganese dioxide added is 0.10
If it is less than 1.0 molar, there will be no effect of addition, and if it exceeds 1.00 mol, grain growth will be inhibited and the dielectric constant will decrease.

If the amount of cupric oxide added is less than 0.01 mol, the insulation resistance will be low, and if it exceeds 0.85 mol, grain growth will be inhibited.
Dielectric constant decreases. 0 amount of smut trioxide added is 0.0
Less than 1 mol; addition has no effect on bacteria, and if it exceeds 0.50 mol, grain growth is inhibited and the dielectric constant decreases by 1°C.

Note that even if only manganese dioxide is added to the above basic composition, the average particle size will be about 50 μm, but the insulation resistance will be low and the electrical properties of the resulting products will vary.

The composition of the present invention having such a composition is sintered and then insulated by applying an insulating agent to its surface.

As the insulating agent used here, a combination of lithium carbonate and/or sodium carbonate and bismuth oxide is preferable because it has a remarkable insulating effect. The mixing ratio of lithium carbonate and/or sodium carbonate and bismuth oxide is
The preferred range is 80 to 25 mol% helium and 20 to 75 mol% bismuth oxide. Furthermore, in addition to the above insulating agents, alkali carbonates and metal oxides, such as manganese oxide,
A combination of copper oxide and the like can also be used as an effective insulating agent. In addition, oxides such as bismuth oxide, manganese oxide, and copper oxide can be used alone or in combination as an insulating agent, but in the case of bismuth oxide or a composite oxide with bismuth oxide, the diffusion temperature must be raised. In the case of manganese oxide or copper oxide, a sufficiently low dielectric strength cannot be obtained, and characteristic values such as dielectric constant are slightly lowered.

The above-mentioned insulating agent made of an alkali carbonate such as lithium carbonate and a metal oxide such as bismuth pentoxide is dispersed in water and a water-soluble glue or varnish, and is applied to both sides of 1 ctA of semiconductor porcelain by about 5 my. Apply (approximately 120
Diffusion treatment is carried out at 0° C. for 30 minutes.

[Example 1] Next, the present invention will be specifically described based on Examples and Comparative Examples.

Examples 1 to 15 and Comparative Examples 1 to 10 Strontium oxide, titanium dioxide and niobium pentoxide in a ratio of 100 mol: 100 mol = 0.2 mol, manganese dioxide and cupric oxide and/or bismuth iodide Strontium carbonate,
Titanium dioxide, niobium pentoxide, manganese dioxide, cupric oxide and bismuth trioxide were each weighed and mixed and ground in a wet ball mill for 24 hours, followed by drying.

This product was calcined in the air at 1050 to 1150°C for 3 hours, cooled, and then finely pulverized. Add a binder to this powder and apply pressure + ton/ci to a diameter of 15111111
It was molded into a disc.

The molded product was calcined in the atmosphere at 700° C. for 1 hour to remove the binder, and then sintered in a nitrogen or argon stream containing 1 to 10% hydrogen by volume. Sintering was performed at 1400 to 1460°C for 4 hours.

The semi-uniform crystal grain size of the sintered body was 50μ as measured by SEM.
It ranged from m to 100 μm. This sintered body has a first
After applying the insulating agent shown in the table on both sides,
A diffusion treatment was performed at 00° C. for 30 minutes to insulate the grain boundary layer.

Silver electrodes are applied and baked on both sides of this insulated semiconductor porcelain.
It was used for measurement. Dielectric constant (ε) and dielectric loss (tanδ)
is the frequency IK) (Z, measured at 25°C.

The insulation resistance was determined by applying a DC voltage of 50 cm at 25° C. and using the resistance value after 60 seconds.

These results are shown in Table 1.

Roughly speaking, the dielectric constant temperature characteristics were calculated in the temperature range from -25°C to +85°C with 20°C as a reference, and the results are shown in FIG. In Fig. 1, the vertical axis is the dielectric constant (%),
The horizontal axis indicates temperature ("C).

As shown in Table 1, Examples 1 to 15 in which manganese dioxide and cupric oxide and/or bismuth trioxide were blended in a specific range to the basic composition of strontium titanate and niobium pentoxide were in accordance with the present invention. Comparative example 1 outside the range of
~10, the electrical conductivity and insulation resistance of X are large,
Moreover, dielectric loss is small. Further, in Examples 1 to 13, in which a mixture of lithium carbonate and/or sodium carbonate and bismuth oxide was used as the insulating agent, the above characteristics were significantly improved.

[Effects of the Invention] As explained above, the porcelain composition of the present invention is obtained by adding specific amounts of manganese dioxide, cupric oxide and/or bismuth trioxide to strontium titanate using niobium pentoxide as a semiconducting agent. , it is possible to provide a capacitor material with a high dielectric constant and low dielectric loss and insulation resistance. Further, after sintering this 11A product, the above characteristics are further improved by applying an insulating agent consisting of lithium carbonate and/or sodium carbonate and bismuth oxide to the grain boundaries.

[Brief explanation of drawings]

FIG. 1 is a graph showing the temperature characteristics of dielectric constant.

Claims (1)

[Claims] 1. 99.0 to 102.0 moles of titanium dioxide and 0.02 to 1 mole of niobium pentoxide per 100 moles of strontium oxide
．． 0.00 mol of manganese dioxide for the main component consisting of 0.00 mol.
A composition for a semiconductor ceramic capacitor, which contains 10 to 1.00 mol of cupric oxide and 0.01 to 0.85 mol of cupric oxide and/or 0.01 to 0.50 mol of bismuth trioxide.