JPS5823731B2 - Method for producing element bodies for semiconductor ceramic capacitors - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing an element body for a semiconductor ceramic capacitor, and it is possible to manufacture an element body for a semiconductor ceramic capacitor that has excellent AC voltage resistance, large capacity, low loss, and high insulation properties. This provides a method that allows you to do so.

At the same time, the purpose is to further simplify the manufacturing method and provide a manufacturing method with high industrial utility value.

Barium titanate-based and strontium titanate-based porcelains have conventionally been used as elements for ceramic capacitors, and these elements themselves have a high dielectric constant and high insulation properties.

Unlike the above-mentioned insulators, the semiconductor ceramic capacitor in the present invention is made of S r Ti O which has a relatively low resistance.
A semiconductor porcelain element whose main component is 8 is used.

In short, a semiconductor porcelain capacitor is a capacitor made by forming a capacitive insulating layer on the grain boundaries, which are the normal outer or inner surfaces of semiconductor porcelain.

The former type is called the surface layer type, and the latter type is called the grain boundary layer type.

Semiconductor ceramic capacitors developed to date generally fall into one of the above-mentioned types.

A thin insulating layer is formed on the surface of a semiconductor porcelain body in the surface layer type, and based on this, a thin insulating layer is formed on the surface of the semiconductor porcelain body. is a structure that acts as a dielectric layer.

Therefore, although it is used for low voltage, it has a feature of large capacity.

On the other hand, grain boundary layer type porcelain capacitors actively utilize the properties of crystal grain boundaries. It has an insulation resistance value suitable for high voltage applications and a large capacity.

By the way, in order to insulate the grain boundaries of semiconducting porcelain,
A method is used in which metals or metal oxides are attached to the surface of semiconductor porcelain, and then heat treated to diffuse metal ions into the grain boundary layer.

As a method for attaching the pigeonhole, metal or metal oxide to the surface of the semiconductor ceramic element, vapor deposition, coating using a solvent, printing, spraying, etc. have been conventionally used.

In the present invention, by using copper as this type of metal and using a plating method as a method for attaching it to semiconductor ceramics, a ceramic body with excellent capacitor properties can be produced.

By using the manufacturing method of the present invention, the following advantages can be obtained.

(1) Copper can be deposited on large amounts of semiconductor ceramic bodies in a short time.

(2) The amount of copper deposited can be easily controlled.

(3) It is easy to make the copper adhesion uniform.

Uniform metal adhesion improves the properties (dielectric constant, loss, edge resistance, resistance, voltage) of semiconductor porcelain.

(4) Copper can be deposited on the entire surface in one operation.

This makes it possible to uniformly make the grain boundary layer highly insulating even in large-sized semiconductor ceramics.

Next, examples of the present invention will be described.

Tie250 for industrial raw materials with a purity of 98 or higher. 0 mol of O, 50,00 mol of 5rCO3, 0.02 mol of Ta205 with a purity of 99.9 or higher and 2,00 mol of Bi2O3 were wet mixed, dried g-v, and then shaped and calcined.

After wet pulverization and drying again, the product was molded into a predetermined shape and fired in a reducing atmosphere consisting of 90% N2 gas and 10% H2 gas.

A predetermined amount of copper was deposited on the surface of the obtained semiconductor porcelain according to a conventional electroless copper plating method as described below, and the grain boundary layer was made into an insulator by heat treatment in air.

Baked silver was used for the electrodes. Next, the plating method in the present invention will be explained.

First, the element is thoroughly washed with a 20% sodium bicarbonate solution and then washed with water.

Next, this element is immersed in a 0.1 S nC12 solution for 2 minutes, and then lightly washed with water.

Next, this element is immersed in a 0.1% PdCl2 solution for 2 minutes, and then lightly washed with water.

Finally, the device was heated at about 30°C containing 50 S' (D copper sulfate, 50 Si'Rochelle's salt, 102 parts caustic soda, and 202 parts formalin (37 parts liquid) in water lt.
Immerse it in a solution and perform electroless plating.

The amount of copper plating depends on the plating time and solution temperature. Although it varies depending on the solution concentration, it was adjusted here by the plating time.

Table 1 shows the relationship between the amount of copper plating on the semiconductor ceramic body and the capacitor characteristics.

Note that the amount of copper is expressed as a proportion to 1 part by weight of the semiconductor ceramic body.

The dielectric constant ε and dielectric loss tan δ are each frequency IKHz.
This is the value measured at

This is the effective voltage at which breakdown voltage occurs when alternating current is applied for one minute.

The insulation resistance was determined by applying a DC voltage of 100 V/rran.
This is the value measured after 1 minute.

All measurements were conducted at 20°C.

However, the X mark indicates a comparative example.

As is clear from the above table, when the amount of copper is within the range of 0.0002 to 0.004 parts by weight per 1 part by weight of semiconductor porcelain, the breakdown voltage is always high and the voltage resistance is excellent. .

Figure 1a and bye show the amount of copper plating, dielectric constant, dielectric loss,
The relationship with insulation resistance is shown by a solid line.

Note that the broken line indicates the value when a paste made by adding copper monoxide powder to an organic solvent was applied uniformly over the entire surface of the semiconductor ceramic body and heat-treated.

The coating amount is expressed as the weight of copper atoms per 1 part by weight of the semiconductor ceramic body.

As is clear from this figure, even if copper is attached to a semiconductor ceramic body by electroless plating, the characteristics of the capacitor obtained are equal to or better than those obtained by the conventional method.

Example 2 Table 3 shows the characteristics of finished products manufactured using the blending ratios shown in Table 2.

The manufacturing procedure was the same as in Example 1. Nb2O,jTa
The composition amount of 2O, tBi203 is the main component iO and SrO
The value is based on 100 moles of the main component.

The amount of copper was 0.002 parts by weight per 1 part by weight of the semiconductor ceramic body.

As is clear from the results in Table 3, even if the composition ratio of the porcelain differs from that of Example 1, the method of the present invention can provide properties equivalent to those of Example 1.

In Examples 1 and 2, typical examples were shown regarding the composition ratio of porcelain, but the method of the present invention i Ti 02 component 49SO~5
Nb
, 0. and 0.05 to 1.5 mol parts of at least one or more of Ta2o and 0.05 mol part of Bi2O3.
A useful element for a semiconductor ceramic capacitor can be produced by applying the composition to which ~5.0 mole parts is added to semiconductor ceramics obtained by firing in a reducing atmosphere.

FIG. 2 ayb shows the changes in AC breakdown voltage and dielectric loss when the thickness of the semiconductor ceramic is changed by solid lines.

Note that the broken line indicates the case where copper monoxide powder was applied to only one side of the semiconductor porcelain body by a coating method.

Here, coating only one side is a coating method; coating the entire surface requires more operations, and is required for industrial mass production.

This is because it will be a disadvantage.

In each case, the amount of copper deposited was 0.002 parts by weight per 1 part by weight of the semiconductor ceramic body.

As can be seen from FIG. 2, as the thickness of the semiconductor ceramic body increases, the method of the present invention improves both AC breakdown voltage and dielectric loss compared to the conventional coating method.

The semiconductor ceramic capacitor element obtained by the manufacturing method of the present invention has a dielectric constant of 40,000 or more and a dielectric loss of 100XI.
It has an insulation resistance of 105 MΩ or less, an AC breakdown voltage of 600 V (effective value) or more, and has industrially excellent characteristics as an element body for a leakage capacitor.

As described above, according to the method of the present invention, the AC voltage resistance was excellent.

It is possible to obtain an element body for a semiconductor ceramic capacitor having a large capacity, low loss, and high insulation resistance.

The grain boundary layer of semiconductor porcelain whose main component is lj5rTi03 is made into an insulator by copper plating and heat treatment in the air, so copper can be uniformly deposited on a large amount of element bodies, and quality can be improved. A stable capacitor can be obtained.

[Brief explanation of the drawing]

FIG. 1 and FIG. 2 are characteristic diagrams for explaining the method of manufacturing a semiconductor ceramic capacitor element body of the present invention, respectively.

Claims (1)

[Claims] 1 TiO2 component 49.50-52. Nb2O and T
The sum of at least one of a205 is 0.05
~1.5 mol parts and 0.05 to 5.0 mol parts of Bi2O3 were added to the composition, and the composition was fired in a reducing atmosphere. 1. A method for manufacturing a semiconductor ceramic capacitor element body, which comprises depositing copper on the obtained semiconductor ceramic by a plating method, and then heat-treating the semiconductor ceramic in air to convert the grain boundaries of the semiconductor ceramic into an insulator. 2. The amount of copper plating is 0.0% copper per 1 part by weight of semiconductor porcelain.
2. The method for manufacturing a semiconductor ceramic capacitor element body according to claim 1, wherein the amount is 0.0002 to 0.004 parts by weight.