JPS6036089B2 - Manufacturing method of porcelain electronic components - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing ceramic electronic components such as grain boundary layer type semiconductor capacitors and voltage nonlinear resistance elements.

Many of the ceramic electronic components are not made of a single composition, but are made of composite compositions with various additives to achieve the required electrical properties.

However, after dispersing several types of inorganic oxides, carbonates, etc., singly or in a mixture, and sometimes in the form of glass in an organic binder, and applying it to the surface of the Akatsuki compact,
In addition to heat treatment to scatter the organic binder, it is also very common to develop or improve specific electrical properties by providing a protective film on the surface of the sintered body or diffusing inorganic substances inside the sintered silk body. Conventionally, a voltage nonlinear resistance element mainly made of zinc oxide, that is, a zinc oxide varistor, is a representative example of a method in which an inorganic material is coated on a fried striped body and heat treated to improve characteristics as described above.

Zinc oxide varistors are made from a mixture of zinc oxide and a small amount of bismuth oxide, cobalt oxide, manganese oxide, chromium oxide, etc., and then fired. In order to improve bubble resistance, a mixture of oxides of boron, silver, bismuth, etc., or in the form of glass, is applied to the surface of the brickwork and thermally diffused. Furthermore, when zinc oxide varistors are used for military equipment, for example, an inorganic substance is coated on the vertical sides of the electrodes and heat treated, and an insulating layer is provided near the surface to prevent deterioration due to creeping discharge. ing. Next, as a representative example for the purpose of developing characteristics, there is a grain boundary layer type semiconductor compound mainly made of barium titanate, strontium titanate, or a composite compound thereof.

Grain boundary layer type semiconductor capacitors are made by adding a pentavalent metal compound such as tantalum Ta or niobium Nb as a semiconducting accelerator to the above compound, and several kinds of additives depending on the purpose, and usually in a reducing atmosphere. The fired sintered body, that is, semiconductor porcelain, is used as a base. After applying a paste in which oxides such as copper and manganese are dispersed in organic/indredder to the surface of the semiconductor porcelain, heat treatment is performed in the atmosphere to form grains. It becomes useful as a capacitor only by diffusing copper, manganese, etc. into the grain boundaries and forming an insulating layer at the grain boundaries.
As mentioned above, it is essential to apply a substance containing metal oxide to the surface of the sintered body and heat treat it to form a union with the basic porcelain.

However, conventionally, the target coating (
For example, screen printing is used to apply a paste containing metal oxides (for example, metal oxides), but as the amount of processing increases, printing unevenness occurs, the process yield decreases, and the number of man-hours increases. Furthermore, there were production problems such as the need for a heat treatment process to remove the binder.

The present invention relates to the results of solving the above-mentioned problems.

That is, after the metal is thermally sprayed, the metal is converted into a metal oxide by heat treatment, and the metal oxide is then diffused into the interior of the porcelain, thereby changing the properties of a part or the whole of the porcelain. Examples of the present invention will be described below.

Example 1 Application example to a voltage nonlinear resistance element based on zinc oxide Zinc oxide (Zn○), bismuth oxide (Bi203), cobalt oxide (Coo), manganese oxide (Mn○), antimony oxide (SQ03), etc. were added in a range of 0.01 to 10 mol% each, and after thorough mixing, a diameter of 2 mm and a thickness of 1 mm was added. Compression mold the enemy's skin.

Thereafter, it was fired at a temperature of 800 to 1500 qo to produce an aggregate mainly composed of zinc oxide. Table 1 shows the performance of the above sintered bodies subjected to various treatments.

In the table, A is no treatment, B is a case of heat treatment at 800 to 120,000, C is a case where a paste containing silver oxide is applied by dip method and heat treated at the same temperature as B, and D is a case of the present invention. As shown in Figure 1, silver is thermally sprayed to form a uniform film (Figure 1a), then heat treated to change the silver to oxide (Figure 1b), and then further heat treated to form a uniform coating inside the porcelain. The process was performed by thermally diffusing the oxide (FIG. 1c). Note that 1 is porcelain, 2 is a metal spray coating, 3 is a metal oxide coating, and 4 is porcelain in which the metal oxide is thermally diffused. Note that an indium gallium alloy was used as an electrode.

In addition, the average value and variance value of various samples were determined with loo0. Table 1 x: Average values.

: Dispersion value V, skin ^ / rib: Varistor voltage Q: Voltage nonlinear index △V, ^ / V, skin ^: Rate of change in varistor voltage after the voltage application test As is clear from Table 1, the change of silver oxide It has been found that those that have undergone thermal diffusion or those that have been thermally diffused by silver thermal spraying have smaller changes after electrocution and have a longer lifespan than those that are not treated or that are only subjected to heat treatment.

Here, the subject test was conducted at a relative humidity of 95% and an ambient temperature of 7000°C, applying a power of 0.8 watts for 100 cycles. Furthermore, when comparing the beach spraying method and the coating method, it is easily recognized from the dispersion values of the characteristics of both that the thermal spraying method clearly has smaller variations in characteristics. It should be noted that E in the table is one that has been subjected to only silver thermal spraying and no further treatment, and it is clear that it can only be used as a resistor. As mentioned above, it is clear that the method of applying a silver film to the surface of a sintered body mainly composed of zinc oxide by thermal spraying and then heat-treating it has uniform properties and maintains stable properties for a long time.

Example 2 Application of strontium titanate (SrTj0
Add 0.1 to 2.0 mol% of niobium oxide ((NQ05) and 0.1 to 2.0 mol% of bismuth oxide (Bi203) to 3), and after mixing, 15 skins x 0.7 ribs. Compression molded into a disk shape, then 1-10% hydrogen and 99-90% nitrogen.
2 at 137,000 to 146,000 in an atmosphere consisting of
Semiconductor porcelain was produced by firing for ~4 hours.

Table 2 shows the performance of the above sintered bodies subjected to various treatments.

Incidentally, as the electrodes, silver electrodes with silver paste baked on both sides at 800 to 90 pi were used. Table 2: Apparent permittivity n6: Dielectric loss rate p: Insulation resistance x: Average value.

:Dispersion value In Table 2, F is the above sintered body with silver electrodes, G is the one with silver electrodes after heat treatment at 90,000 to 120,000, and Day is the sintered body with silver electrodes formed by screen printing. Case 1 is the case of the present invention when the surface of the sintered body is coated and heat treated at the same temperature as G, and after the surface of the sintered body is coated with copper, it is heat treated as shown in Figure 1. be.

In addition, J is a case in which a sintered body is subjected to copper blasting and an indium and gallium alloy is used as an electrode.

In addition, the average value and variance value of various samples are shown in the table with loo0ke. As is clear from Table 2, galvanized steel with thermal diffusion or copper spraying with thermal diffusion has much better performance as a capacitor than other cases. That is clear.

Comparing the galvanized steel coating method and the copper spraying method,
It is clear from the comparison of dispersion values that the variation in properties is much smaller in the thermal spray method. As mentioned above, it can be seen that the properties of semiconductor porcelain that has been thermally sprayed with copper and heat treated are extremely stable.

This is because by using the thermal spraying method, the amount of copper coating is clearly determined, so there is less variation in the amount of coating unlike the conventional coating method. The amount of copper coated by thermal spraying is easily determined by the thickness of the copper wire, the applied voltage, the copper wire feed speed, and the spraying time if the distance between the object and the spraying port is kept constant.

Next, the workability of the coating method and thermal spraying method will be explained. The same person was asked to coat the semiconductor porcelain according to Example 2 with copper or galvanized steel, and the workability was examined.

One is traditional screen printing and the other is thermal spraying. The work was carried out for one hour after completion of preparation for each method.

Furthermore, the characteristics of the semiconductor ceramic capacitors obtained using both methods were measured to determine the yield.

Figure 2 shows the number of man-hours and yield, and it is clear from Figure 2 that when the foundation firing method is used, the workability is extremely good and the yield rate is excellent. As described above, the method of the present invention makes it possible to accurately quantify the substances that are secondarily added to the firing body for the first time by applying the blasting technique, and it is possible to accurately quantify the ceramic composition, which was not possible with conventional coating methods. In addition to being able to measure production efficiency, it is also easy to work with, making it useful for mass production.

In the examples, a voltage nonlinear resistance element mainly made of zinc oxide and a semiconductor capacitor mainly made of strontium titanate were shown as examples, but if the method of the present invention is applied to other ceramic electronic components, the characteristics can be improved. Needless to say, it can be easily changed.

In particular, it has already been shown that semiconductor porcelain capacitors based on barium titanate or a composite compound of strontium titanate and barium titanate can achieve the same effect as semiconductor capacitors based on strontium titanate. It has been confirmed.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing the manufacturing process of a porcelain electronic component according to an embodiment of the present invention, and FIG. 2 is a diagram comparing the number of steps and yield between the conventional screen printing method and the method of the present invention. Figure 1 Figure 2

Claims (1)

[Claims] 1. A method for manufacturing a porcelain electronic component including a step of diffusing a metal compound inside the porcelain, in which a metal is thermally sprayed onto the surface of the porcelain to form a thermally sprayed coating, and then the thermally sprayed coating is heat-treated to convert the metal into a metal oxide. A method for manufacturing a porcelain electronic component, characterized in that the metal oxide is diffused into the interior of the porcelain by further heat treatment.