JPH0673341B2 - Manufacturing method of bottomed cylindrical capacitor - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a cylindrical capacitor, and more particularly to an improvement in a method for forming an inner surface electrode on the inner surface of a cylindrical cylinder body with a bottom.

2. Description of the Related Art In a bottomed cylindrical capacitor, an inner surface electrode 1 and an outer surface electrode 2 are formed on the inner surface and outer surface of a cylindrical ceramic body whose one end is closed, as shown in FIG. 3 (a) or (b). A predetermined electrostatic capacity is ensured by the facing area of the electrodes 1 and 2, the facing distance, and the dielectric constant of the porcelain body 3. In the capacitors (a) and (b), the inner surface electrode 1 has a bottom inner surface 3a of the cylindrical porcelain body 3.
The other structures are the same except that they are formed in or not.

In such a bottomed cylindrical capacitor, the inner electrode 1 is formed by inserting the rotary pin 5 to which the metal paste 4 of Ag-Pd system or the like is attached into the porcelain body 3 as shown in FIG. After inserting and forming a metal paste coating film on the inner surface of the porcelain body 3,
The conventional general method is to perform baking.

In FIG. 3, one end 1a of the inner surface electrode is folded back to the outer surface of the porcelain body, and although the folded back electrode portion 1a cannot be formed by the rotating pin 5, the outer surface electrode 2 is formed by using a transfer roller (not shown) or the like. It is formed at the same time when forming.

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention However, the above-described method of applying a metal paste using a rotating pin has the following problems.

When the metal paste is applied to the inner surface of the porcelain body using the rotating pin 5, the amount of the metal paste adhered on the inner surface of the rotating pin varies, so that the thickness of the coating film on the inner surface of the porcelain body becomes uneven or the metal paste bleeds. The edges of the coating often wavy as shown by the broken line in Fig. 4 (b),
It is difficult to form an inner surface electrode having a predetermined area and thickness.

In the case of applying the metal paste to the inner surface 3a of the bottom portion of the porcelain body by further deepening the insertion amount of the rotary pin 5 into the porcelain body, in addition to the problem described in It is difficult to apply the metal paste to (3b in Fig. 4 (c)), and therefore the metal paste coating film 1b applied to the bottom inner surface 3a after baking is isolated and applied to the inner surface of the cylindrical porcelain body. In addition, a so-called electrode disconnection phenomenon in which electrical contact with the metal paste coating film 1c is lost easily occurs.

When the metal paste is applied using a rotating pin, if the inner diameter of the porcelain body 3 changes, the rotating pin must be replaced with a rotating pin having an outer diameter corresponding to it, which is necessary for replacement work and accompanying pin mounting position adjustment work. It takes a lot of time and causes a decrease in operating rate.

In the method of applying a metal paste using a rotating pin, it is extremely difficult to perform a multi-process of applying a metal paste to the inner surfaces of many porcelain bodies at once, and improvement in manufacturing efficiency cannot be expected.

The metal paste application method using the rotating pin cannot be applied to the case where the porcelain body is a rectangular tube type other than the circular shape.

It is an object of the present invention to provide a useful method for manufacturing a bottomed cylindrical capacitor which can solve the above problems.

Means for Solving the Problems In order to solve the above problems, the present invention, in a state where the pressure in the tank is normal, the one end opening of the bottomed cylindrical porcelain body in the metal paste bath stored in the tank Immerse, and then pressurize the pressure inside the tank to create a pressure difference between the pressure inside the tank and the pressure inside the porcelain body, and apply metal paste to the inner surface of the porcelain body to reduce the pressure inside the tank. In this state, the one-end opening of the bottomed cylindrical porcelain body is immersed in the metal paste bath stored in the tank, and then the pressure inside the tank is restored by recompressing the inside of the tank. Applying a metal paste to the inner surface of the porcelain body with a pressure difference between them, and with the pressure inside the tank reduced, one end opening of the bottomed cylindrical porcelain body in the metal paste bath stored in the tank Dip, and after that, the pressure in the tank is restored and the pressure is further increased for a predetermined time to the porcelain element. Applying a metal paste on the inner surface, characterized by.

Effect According to the present invention, since the metal paste is pushed inward from the one end opening of the porcelain body by the pressure difference between the inside and the inside of the porcelain body, the inner surface of the porcelain body is where the metal paste is pushed up. The metal paste will be applied up to.

In this case, the height at which the metal paste is pushed up is determined by the pressure difference between the inside and outside of the cylinder regardless of the inside diameter of the cylinder, so if the pressure difference is kept constant, even if the inside diameter of the cylinder is large or small. The metal paste can be pushed up and applied to a certain height on the inner surface of the cylinder, and if the pressure difference is adjusted, it is possible to increase or decrease the area of application of the metal paste on the inner surface of the cylinder.

Furthermore, by controlling the depth at which the one end opening of the porcelain body is dipped in the metal paste, a folded electrode formed by folding back the part of the outer surface of the porcelain body can be formed at the same time.

There are roughly two methods of applying a metal paste to the inner surface of the porcelain body by providing a pressure difference between the inside of the tank and the inner surface of the porcelain body.

A method of immersing an opening at one end of a bottomed cylindrical porcelain body in a metal paste bath while keeping the inside of the tank at normal pressure, and then pressurizing the inside pressure of the tank.

A method of immersing the one-end opening of a bottomed cylindrical porcelain body in a metal paste bath while depressurizing the inside of the tank, and then re-pressurizing the inside of the tank.

In the above method, theoretically, if the depressurized state in the tank is brought close to a vacuum (0 mmHg) as much as possible, the inside of the porcelain body will be in a vacuum state. It is pushed up to the inner surface of the bottom portion, so that the metal paste can be applied to the entire inner surface of the porcelain body.

However, in reality, when the inside of the tank is brought closer to a vacuum state, (a) the solvent in the metal paste becomes more vigorous, the paste surface dries, and the wettability with the paste when the porcelain body is immersed becomes worse. .

(B) There are air voids that cannot be removed at atmospheric pressure in the metal paste, but when they are depressurized to a vacuum state, they grow greatly and cause the metal paste surface to wavy.
Therefore, when the porcelain body is dipped, the edge shape of the folded electrode is particularly deteriorated.

Such a harmful effect occurs. Therefore, actually, it is not appropriate to reduce the depressurization in the tank to 50 mmHg or less, and thus it is difficult to apply the metal paste to the inner surface of the bottom of the porcelain body in terms of realization by the above method.

Therefore, in order to apply the metal paste to the inner surface of the bottom portion of the porcelain body even if the depressurized state in the tank is not reduced to 50 mmHg or less, after the pressure in the tank is restored, further pressurization is performed. However, in this case, since the depressurized state in the previous step is not a vacuum state, a slight air remains inside the porcelain body even after the pressurization, and this causes the metal paste to be spread on the entire inner surface of the bottom of the porcelain body. Prevent application. However, this can also be prevented by maintaining the pressurized state for a predetermined time. That is, if the pressurized state in the tank is maintained for a predetermined time,
Depending on the wettability of the metal paste, the air is pushed away and the metal paste wraps around and can be applied to the entire inner surface of the bottom of the porcelain body.

Example FIG. 1 is a diagram illustrating a method of applying a metal paste to the inner surface of a cylindrical ceramic body with a bottom by decompressing the inside of a tank and then restoring the pressure, as an example of the present invention. First, as shown in FIG. 4 (a), the bottomed cylindrical porcelain body 3 is held by the holding plate 11 with the opening 3b at one end thereof facing downward, and stored in the pressure-adjustable processing tank 12. It is placed on the bath of the metal paste 13 such as Ag, Ag-Pb, etc. Then, the inside of the processing tank 12 is degassed by a vacuum pump (not shown) or the like to reduce the pressure to a predetermined pressure. The predetermined pressure is selected to be 50 mmHg or more, preferably 70 mmHg or more for the reason described in the section of action.
The number of the porcelain bodies 3 held on the holding plate 11 is actually several hundreds to several thousands, but only one is shown in this figure for easy understanding.

When the pressure reduction in the processing tank 12 is completed, as shown in FIG. 6B, the ceramic body 3 is immersed in the bath of the metal paste 13 from the one end opening 3b side. The depth of immersion is adjusted so as to have a length necessary for the folded electrode, for example.

Next, the outside air is introduced into the processing tank 12 to restore the atmospheric pressure. Then, the metal paste 13 is pushed up into the porcelain body 3 by the pressure difference between the inside and outside of the porcelain body 3 as shown in FIG.

Thus, when the pushing up of the metal paste 13 is completed, the inside of the processing tank 12 is degassed and decompressed again as shown in FIG. 2D, and whether the pressure outside the porcelain body 3 is the same as the pressure inside the porcelain body 3. Alternatively, by slightly lowering the pressure, the excess metal paste 13 pushed up inside the porcelain body 3 is removed. This step may be performed with the porcelain body 3 pulled up from the metal paste 13. Then, when the porcelain element body 3 is pulled up from the bath of the metal paste 13 as shown in FIG. 5E, the coating film 1 of the metal paste is formed from the inner surface of the porcelain element body 3 and the opening 3b to the outer surface.

By a series of operations as described above, the metal paste 13 is pushed up inside the porcelain element body 3, the excess metal paste is removed, and the coating film 1 for the inner surface electrode is formed on the inner surface and a part of the outer surface of the porcelain element body 3. When formed, the pushed-up metal paste 13 adheres sufficiently evenly over the entire inner surface of the porcelain body 3, so that the coating film 1 is not blurred and the film thickness is substantially constant. Moreover, if the pressure difference between the inside and outside of the porcelain body 3 is made constant, the height at which the metal paste 13 is pushed up will always be constant, and there will be no waviness on the top edge irregularities of the coating film 1. It is always constant and does not vary.

The second deaeration and depressurization operation for extracting the excess metal paste 13 from the porcelain body 3 is necessary when the metal paste 13 inside the porcelain body 3 is not naturally discharged due to surface tension or the like. However, when the inner diameter of the porcelain body 3 is large and the metal paste 13 therein is naturally discharged, it is not necessary to dare to do so.

As described above, the application of the metal paste to the inner surface of the porcelain body 3 and the portion corresponding to the folded electrode portion is completed, and the coating film 1
When the is dried, it is necessary to form a predetermined external electrode.
The external electrodes may be formed by any method such as brush coating or roller coating, but the immersion method may be used for mass production. A specific example of this immersion method will be described below. Figure 1 (e)
The porcelain element body 3 obtained in step (f) is turned upside down and temporarily fixed to the holding plate 11, and as shown in the figure (g), the porcelain element body 3 is fixed to a predetermined depth with a metal paste. Immerse in bath of 13. In this case, since the lower end of the porcelain body 3 is closed by the bottom portion 3c, the metal paste does not enter the inside of the porcelain body, and therefore the pressure in the processing tank 12 may be atmospheric pressure.

Then, as shown in FIG. 5C, the porcelain body 3 is pulled up from the bath, the coating film 2 attached to the outer surface of the porcelain body 3 is dried, then removed from the holding frame 11, and the next baking step (not shown). ) And bake coatings 1 and 2 to form inner and outer electrodes. The manufacture of the cylindrical capacitor manufactured in this manner is as shown in FIG.

Next, FIG. 2 shows another embodiment of the present invention, which is a method of applying a metal paste to the entire inner surface of the porcelain body including the inner surface of the bottom by decompressing the interior of the tank and then restoring the pressure and then applying pressure for a predetermined time. It is a figure explaining. Since the depressurization and the decompression of the inside of the tank are the same as in the above-mentioned embodiment, the processing tank 12 whose pressure can be adjusted is the same as that in FIG. 1, but the processing tank is omitted in the figure and the porcelain body 3 is used. And only the metal paste 13 are shown. First, the inside of the tank is decompressed (Fig. (A)), the lower end opening 3b of the porcelain body 3 is immersed in the bath of the metal paste 13 (Fig. (B)), and then the pressure in the tank is restored (Fig. Since the steps up to this point are exactly the same as those in Fig. 1 (a), (b), and (c), a detailed description is omitted, and the procedure after recompression is described. For example, the metal paste 13 is pushed up inside the porcelain body 3 due to the pressure difference between the inside and outside of the porcelain body 3, but at this time, the upper surface of the metal paste 13 does not reach the bottom inner surface 3a of the porcelain body 3. That is, the upper surface of the metal paste 13 and the porcelain body 3
Between the bottom inner surface 3a and the bottom inner surface 3a, there remains an air 14 that is determined by the reduced pressure value.

Then, at the same time when the pressure in the tank is restored, 1000-5000 mmHg,
Desirably, when the pressure is applied at 2000 mmHg, the inside of the porcelain body 3 has a granular air 14 as shown in FIG. 2D, but the metal paste 13 contacts the bottom inner surface 3a of the porcelain body 3. Further pushed up. Then, when this pressurized state is maintained for 5 to 30 seconds, the wettability of the metal paste 13 causes the metal paste 13 to push away the granular air 14 and wrap around to the bottom inner surface 3a.

Thus, the metal paste 13 adheres to the entire inner surface 3a of the bottom of the porcelain body.

Then, the inside of the tank is decompressed again, and the metal paste 13 pushed up inside the porcelain body is lowered to the original level as shown in FIG. The depressurization value at this time is preferably equal to or smaller than the depressurization value in the first step by about 10 mmHg. When the pressure reduction is completed, the porcelain body 3 is raised, the attached coating film is dried, and then the metal paste is applied and dried on the outer surface of the porcelain body in the same manner as described in the first embodiment.
A bottomed tubular capacitor is manufactured by baking. The bottomed tubular capacitor thus manufactured is manufactured as shown in FIG.

In each of the above examples, a pressure difference is provided between the inner surface of the porcelain body and the inside of the tank by decompressing the inside of the tank and then restoring the pressure. As a method of providing, it is needless to say that a method of immersing the one end opening of the bottomed cylindrical porcelain body in a metal paste bath and applying pressure in a state where the inside of the tank is at normal pressure may be used. In this case, the metal paste can be applied to a desired depth from the one end opening of the inner surface of the porcelain body depending on the degree of pressurization. The metal paste can be applied to the entire inner surface of the porcelain element body including the inner surface of the bottom portion by the same effect as in the case of the embodiment.

Effects of the Invention As described above, according to the method for manufacturing the tubular capacitor of the present invention, the coating film before electrode baking may be blurred,
Since there is almost no variation in the area, size, thickness, etc. of the coating film, and the edges of the coating film are not wavy, it is possible that the internal surface electrodes formed by baking the coating film have variations in area. Almost no defective capacity, poor electrical characteristics due to variation in electrode thickness, etc. are produced, and the production yield is improved by about 10 to 20%.

Moreover, when forming the coating film for the internal electrode, simply by setting the pressure difference between the inside of the porcelain body and the tank to be a predetermined pressure difference, whether the inner diameter of the porcelain body is large or small, Even if the length of the porcelain body is different, it is possible to form a coating film with a predetermined inner surface electrode size, and it is troublesome to replace and adjust the rotating pin etc. every time when the inner diameter and length of the porcelain body are changed, as in the past. Skilled work is completely unnecessary. Furthermore, since the manufacturing method of the present invention is a dipping method that does not use a rotating pin,
The present invention can be applied not only to a circular porcelain body but also to a rectangular porcelain body. Also, since the atmospheric pressure inside and outside the hollow can be finely adjusted by changing the atmospheric pressure of the processing tank itself in stages, it is possible to obtain a coating size that is much more accurate than the conventional method and to corrugate the coating surface. It can be prevented and the thickness can be made uniform.

Moreover, according to the manufacturing method of the present invention, by using a large-sized processing tank, it is possible to perform multi-processing in which a metal paste is applied to hundreds to thousands of porcelain bodies at a time, and the productivity is reduced to the conventional one. It is possible to dramatically improve the manufacturing cost by several tens to several hundreds, and to significantly reduce the manufacturing cost.

Further, in the above multi-processing, since the pressure difference between the tank internal pressure and the inside of each porcelain body occurs and acts in the same manner, there is a remarkable effect that the coating finish state can be made uniform. Can be obtained according to the above effects.

[Brief description of drawings]

FIGS. 1 (a) to (h) are diagrams for explaining one embodiment of the present invention, FIGS. 2 (a) to (f) are diagrams for explaining another embodiment of the present invention, and FIG. 3 (a). ) (B) is a side cross-sectional view showing a bottomed cylindrical capacitor, FIG. 4 (A) is a view showing a conventional method of applying a metal paste to the inner surface of the porcelain body, and FIG.
FIG. 3 is a diagram for explaining problems in the conventional method. 3 ... Porcelain body, 3a ... Bottom inner surface, 3b ... Opening, 13 ...
… Metal paste.

Claims (3)

[Claims] 1. By immersing one end opening of a bottomed cylindrical porcelain body in a metal paste bath stored in a tank while keeping the tank at a normal pressure, and then pressurizing the tank internal pressure. A method of manufacturing a cylindrical capacitor, characterized in that a pressure difference is provided between a tank internal pressure and a surface pressure inside a porcelain body, and a metal paste is applied to a peripheral surface of the porcelain body. 2. The pressure inside the tank is reduced by immersing the one end opening of the bottomed cylindrical porcelain body in a metal paste bath stored in the tank and then restoring the pressure in the tank. And a pressure difference between the surface pressure inside the porcelain body and a metal paste is applied to the peripheral surface of the body inside the porcelain body. 3. While the pressure inside the tank is reduced, the one end opening of the bottomed cylindrical porcelain body is immersed in a metal paste bath stored in the tank, and then the pressure inside the tank is restored, and further for a predetermined time. A method for manufacturing a cylindrical capacitor, which comprises applying a metal paste to the inner surface of a porcelain body by applying a predetermined pressure.