JPH058850B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a cylindrical capacitor, and particularly to a method for forming inner electrodes thereof.

Prior Art As shown in FIG. 4, a conventional general cylindrical capacitor is manufactured by forming an inner electrode 2 and an outer electrode 3 on the inner and outer surfaces of a cylindrical ceramic body 1, respectively. It is constructed so that capacitance is taken at the opposing portions of both electrodes 2 and 3, as shown in the figure.
This outer electrode 3 is often extended to one end of the porcelain body 1, and the inner electrode 2 is extended to one end of the porcelain body 1.
It is common that the porcelain body 1 is folded back from the other end surface to the outer surface to form the porcelain body 1.

By the way, when forming the inner surface electrode 2 and the outer surface electrode 3 in such a cylindrical capacitor,
Generally, it was manufactured by the following method.

That is, as shown in FIG. 5A, first, the porcelain element 1 is
Hold one end of the Ag, Ag-Pd with a suitable holder 5.
By inserting a rotary pin 7 or the like to which a metal paste 6 such as a metal paste 6 is attached into the inside of the porcelain element 1, and applying the metal paste 6 to a portion of the inner surface of the porcelain element 1 where the inner surface electrode 2 is to be formed, A coating film 2a (see FIG. 5B) is formed.

Next, as shown in FIG. 5B, the transfer roller 8 to which the metal paste 6 is applied is used to apply the metal paste 6 to the portions of the outer surface of the porcelain body 1 where the outer surface electrode 3 and the extraction electrode portion 4 are to be formed. Apply, coating film 3
Form a, 4a. Further, there are cases where, for example, brush painting or spatula painting is performed without using the transfer roller 8. Incidentally, the metal paste is applied to the other end surface of the porcelain body 1 by an appropriate means such as wrapping by a transfer roller 8.

Thereafter, these coating films 2a, 3a, and 4a are baked to form an inner electrode 2 and an outer electrode 3, thereby producing a cylindrical capacitor as shown in FIG.

Problems to be Solved by the Invention However, when manufacturing a cylindrical capacitor using this method, the following problems occur.

Metal paste 6 using the above rotating pin 7 etc.
When applied to the inner surface of the porcelain body 1, the coating film 2a may be scratched, the thickness of the coating film 2a may become uneven, or the metal paste may bleed due to variations in the amount of metal paste deposited on the rotating pin 7. Paint film 2
The edge of a is often undulating in an uneven manner as shown by the dashed line in FIG. 4, and it is not easy to form the inner surface electrode 2 having a predetermined area and thickness.

When applying the metal paste 6 to the inner surface of the porcelain element 1 using the rotating pin 7 as described above, each time the inner diameter of the porcelain element 1 changes, it is necessary to adjust the rotation pin by replacing it with a rotating pin of the corresponding diameter. Therefore, this replacement and adjustment work requires time and skill. As described above, in the conventional manufacturing method, it takes time to replace the rotary pin 7, adjust it, clean it, etc., and thus the operating rate decreases.

In the conventional method, multi-processing of forming electrodes on a large number of porcelain bodies 1 at once is not possible, so it is difficult to improve manufacturing efficiency.

When applying the metal paste 6 to the inner surface of the porcelain element 1 using the rotating pin 7 as described above, it is possible to apply only to a cylindrical porcelain element. Not applicable.

There were other problems.

The present invention solves these conventional problems, and
It is an object of the present invention to provide a method for manufacturing a cylindrical capacitor that improves quality and is highly suitable for mass production, particularly a method for forming inner electrodes.

Means for Solving the Problems In order to achieve the above object, the manufacturing method of the present invention includes providing a surface plate on which a metal paste is evenly applied on the top surface in a treatment tank whose pressure can be freely adjusted; The open end side of a cylindrical porcelain element whose one end is blind is brought into contact with the porcelain element, and then the porcelain element is lifted off the surface plate and the open end is immersed in the metal paste in the treatment tank. The method is characterized in that the atmospheric pressure is higher than the atmospheric pressure inside the porcelain element, and a metal paste is applied to the inner surface of the porcelain element and the outer surface near the open end.

Effect According to the above manufacturing method, when the open end side of the cylindrical porcelain body is brought into contact with a surface plate on which a metal paste layer is placed on the upper surface, the metal paste adheres to the portion corresponding to the lead-out electrode portion of the inner electrode. do. Next, with the porcelain element floating from the surface plate and its open end immersed in the metal paste, the pressure inside the treatment tank (outside the porcelain element) is made higher than the pressure inside the porcelain element. The metal paste is pushed up into the porcelain body from the open side due to the pressure difference. Therefore, the metal paste is applied to the inner surface of the porcelain element up to the point where the metal paste is pushed up.

In this case, since the longitudinal dimension of the metal paste applied to the extraction electrode portion is constant depending on the thickness of the metal paste applied on the surface plate, variations can be suppressed to a small level. In addition, the height at which the metal paste is pushed up is determined by the pressure difference between the inside and outside of the porcelain body, regardless of the inner diameter of the porcelain body, so if the pressure difference is held constant, the inner diameter of the porcelain body is Even if the metal paste is small, it is possible to push the metal paste up to a certain height on the inner surface of the porcelain body and apply it, and by controlling the pressure difference,
It is also possible to increase or decrease the metal paste application area on the inner surface of the porcelain body.

Note that the manufacturing method of the present invention can be applied to both a cylindrical porcelain element whose both ends are open and a cylindrical porcelain element whose only one end is open. In the case of a cylindrical porcelain body with both ends open, it is necessary to close one end with another suitable closing member to make it blind. On the other hand, in the case of a cylindrical porcelain body with a bottom, one end is closed by the bottom of the porcelain body, so there is no need to provide a closing member.

Example Hereinafter, the present invention will be explained in detail with reference to Examples.

Figures 1A to 1A are explanatory diagrams sequentially explaining one embodiment of the manufacturing method of the present invention (inner surface electrode forming method), and Figure 1A shows a cylindrical porcelain body 1 formed with both ends open. . As shown in FIG. Deploy. In the figure, reference numeral 6 denotes a metal paste, which is piled up on the surface plate 11 with a constant thickness H corresponding to the dimensions of the lead electrode portion 4 (FIG. 4) of the cylindrical capacitor. Surface plate 11
The upper surface is sufficiently wide, so that even if a large number of porcelain bodies are dipped into the metal paste 6 at the same time, the upper surface level of the metal paste does not change. It should be noted that the number of porcelain bodies 1 held by the holding plate 9 is shown only briefly in order to facilitate understanding.

Next, the inside of the processing tank 10 is pumped with a vacuum pump (not shown).
The pressure is reduced until the predetermined pressure is reached. When the pressure reduction in the processing tank 10 is completed, as shown in FIG.
1. At this time, the metal paste 6 adheres to the inner and outer surfaces in the vicinity of the opening end 1b with the length of the dimension H.

Thereafter, as shown in FIG. When outside air is introduced to restore the pressure inside the processing tank 10 to atmospheric pressure,
A pressure difference is generated between the inside and outside of the porcelain element 1, and the metal paste 6 is pushed up into the interior of the porcelain element 1, filling the inner surface of the porcelain element 1.

When the pushing up of the metal paste 6 is completed in this way, the inside of the processing tank 10 is degassed again as shown in Figure E.
When the pressure is reduced and the air pressure outside the porcelain element 1 is made equal to or slightly lower than the air pressure inside the porcelain element 1, the excess metal paste 6 pushed up inside the porcelain element 1
is scraped off. Then, as shown in the figure, when the porcelain element 1 is pulled upward, metal coating films 2a and 4a for inner electrodes are formed on the inner surface of the porcelain element 1 and from the opening 1b to the outer surface.

In this way, the metal paste 6 is pushed up into the inside of the porcelain element 1, the excess metal paste is scraped off, and the metal coating film 2a for inner electrodes formed on a part of the inner and outer surfaces of the porcelain element 1 is formed. 4a, the pushed-up metal paste 6 adheres evenly and sufficiently from the inner surface of the porcelain body 1 to the outer surface near the opening end 1b, so that even after the film is formed, there is no blurring and the film thickness is also reduced. It remains almost constant. In particular, the dimensions of the metal coating film 4a for the extraction electrode section are determined by the thickness H of the metal paste 6 applied on the surface plate 11, so that no dimensional variations occur. Moreover, if the pressure difference between the inside and outside of the porcelain body 1 is constant, the height at which the metal paste 6 is pushed up is always constant, and the metal coating film 2
The upper edge of a is no longer wavy and the coating area is always constant.

In addition, the second degassing and depressurization operation to scrape off the excess metal paste 6 from the porcelain body 1 is performed when the metal paste 6 inside the porcelain body 1 is not naturally discharged due to surface tension or the like. However, if the inner diameter of the porcelain body 1 is large and the metal paste 6 inside is naturally discharged, it is not necessary to do so. Furthermore, this second degassing and depressurization operation may be performed in the state shown in FIG.

As described above, from the inner surface of the porcelain body 1 to the open end 1
When the metal paste is applied over the outer surface of b,
It is dried, and then a metal coating film for an external electrode is formed.

This metal coating film for the external electrode may be formed by any method such as brush coating or transfer roller method, but it is preferable to use a dipping method in consideration of mass productivity. Hereinafter, an example of a method for forming an outer surface electrode based on a dipping method will be explained in detail.

FIGS. 2A to 2D are explanatory diagrams sequentially illustrating a method of forming an outer surface electrode by a dipping method.

First, as shown in FIG. Inject and pressurize. The degree of this pressurization is such that when the porcelain element 1 is further immersed in the bath of the metal paste 6, the metal paste 6 is applied to the porcelain element 1.
It suffices as long as it does not penetrate inside. Specifically, it is desirable to pressurize to a pressure higher than atmospheric pressure by about 100 mmHg.

Next, as shown in FIG. 7B, the opening 1c of the porcelain body 1 is arranged so as to be in contact with the bath surface of the metal paste 6. Then, the inside of the processing tank 3 is degassed using a vacuum pump (not shown) or the like to reduce the pressure until a predetermined pressure is reached, and the air pressure outside the porcelain body 1 is reduced.
The pressure should be lower than the internal pressure.

Next, while maintaining this pressure difference, the porcelain body 1 is immersed in a bath of metal paste 6 as shown in FIG. The depth of this immersion may be determined according to the required dimensions of the external electrode. When the porcelain element 1 is immersed under a pressure difference, the pressure inside the porcelain element 1 is high, which prevents the metal paste 6 from penetrating into the porcelain element 1. Paste 6 adheres. Therefore, when the porcelain element 1 is pulled out of the bath of metal paste 6 as shown in FIG.

Metal coating films 2a and 3 formed as described above
A and 4a are dried and baked to become inner electrodes and outer electrodes, completing a cylindrical capacitor. Note that the coating films 2a and 3a for the inner surface electrode and the outer surface electrode may be formed first.

The cylindrical capacitor manufactured in this way is
A clear clearance is formed between the outer surface electrode 3 and the extraction electrode portion 4 of the inner surface electrode 2, and short circuits are prevented.

Furthermore, in the above-mentioned embodiment, the metal paste 6 is applied by reducing the pressure inside the tank and then restoring the pressure to form the metal coating films 2a and 4a for inner electrodes.
After the initial treatment tank 10 is brought to atmospheric pressure and the porcelain element 1 is brought into contact with the surface plate 11, the porcelain element 1 is placed on the surface plate 1.
1 and with its opening 1b immersed in the metal paste 6, the inside of the treatment tank 10 is pressurized to create an air pressure difference between the inside and outside of the porcelain body 1. It goes without saying that the present invention can also be carried out by a method in which the inner surface is filled with metal paste 6 and then the pressure is returned to normal pressure. In addition, in FIGS. 1 and 2, only one magnetic body 1 is shown to be held on the holding plate 9 for ease of understanding, but it goes without saying that it can be carried out even with a plurality of magnetic bodies 1. .

Furthermore, porcelain element 1 according to the manufacturing method of the present invention
may be placed in the treatment tank with one end blind.
Even a porcelain body 1 having a bottom portion can be manufactured in the same manner. However, if it is desired to form an inner surface electrode also on the inner surface of the bottom, residual air 12 may be generated as shown in FIG. 3A in the restored pressure state of FIG. 1D. However, in this case, by applying appropriate pressure,
As shown in FIG. 3B, the metal paste 6 can be pushed up to the point where it comes into contact with the inner surface of the bottom 1a of the porcelain body 1, and by further maintaining this state for a predetermined time, the metal paste 6 can be pushed up as shown in FIG. 3C. Paste 6
This pushes away the granular air 12 and wraps around the inner surface of the bottom portion 1a, making it possible to form an inner surface electrode on the bottom portion 1a as well. Further, the outer electrode can be formed by any method such as a transfer roller method or a dipping method, so that the desired cylindrical capacitor can be easily manufactured. Note that when forming the outer electrode using a transfer roller or brush painting, unevenness may occur as shown by the dashed line in Figure 5, but this does not pose a problem as there is no unevenness on the extraction electrode side. .

Effects of the Invention As detailed above, the method for manufacturing a cylindrical capacitor according to the present invention prevents the occurrence of blurring in the metal coating film before electrode baking, and variations in the area, dimensions, thickness, etc. of the metal coating film. There is almost no possibility that the edge of the metal coating will be uneven or wavy, so there will be no capacitance defects due to variations in the area of the inner electrode formed by baking the metal coating, or variations in the thickness of the electrodes. Defects in electrical characteristics, etc. almost no longer occur, and production yields improve by about 10 to 20%.

Furthermore, since the dimensions of the extraction electrode section are always formed to a predetermined size, there is no risk of short-circuiting between the extraction electrode section and the outer surface electrode as in the conventional case. Moreover, when forming this metal coating film, it is only necessary to set the pressure difference between the inside and outside of the porcelain body to a predetermined pressure difference, and regardless of whether the inner diameter of the porcelain body is large or small, the porcelain Since it is possible to form a coating film with a predetermined inner electrode size even if the length of the body is different, it is no longer necessary to replace and adjust the rotating pin etc. every time the inner diameter or length of the porcelain body differs. Troublesome work that requires skill is completely unnecessary.

In addition, since it is a dipping method that does not use a rotating pin, it has the advantage of being able to apply the metal paste evenly and evenly not only to cylindrical porcelain bodies but also to rectangular cylindrical porcelain bodies. .

[Brief explanation of drawings]

1A to 1F are explanatory diagrams sequentially explaining a method for manufacturing a cylindrical capacitor (inner surface electrode forming method) according to an embodiment of the present invention, and FIGS. 2A to 2D sequentially explaining a method for forming outer surface electrodes. Explanatory diagrams, Figures 3A to 3C are explanatory diagrams illustrating an example of a method for manufacturing a cylindrical capacitor with a bottom, Figure 4 is a cross-sectional view of a cylindrical capacitor, and Figures 5A to 5B are diagrams showing a conventional manufacturing method. FIG. 2 is a sectional view of a main part showing an example. 1...Porcelain element body, 1b...Open end, 6...Metal paste.

Claims (1)

[Scope of Claims] 1. A surface plate on which metal paste is evenly spread on the upper surface is provided in a treatment tank whose pressure can be freely adjusted, and the open end side of a cylindrical porcelain element whose one end is blind is provided on the surface plate. Then, with the porcelain element floating from the surface plate and its open end immersed in the metal paste, the pressure in the treatment tank is made higher than the pressure inside the porcelain element, and the porcelain element is A method for manufacturing a cylindrical capacitor, characterized by applying a metal paste to the inner surface of the body and the outer surface near the open end. 2. The method according to claim 1, wherein the metal paste is applied to the inner surface of the porcelain body by setting the pressure inside the porcelain body to be lower than atmospheric pressure and setting the pressure in the processing tank to atmospheric pressure. Method of manufacturing cylindrical capacitors. 3. The metal paste is applied to the inner surface of the porcelain element by setting the pressure inside the porcelain body to atmospheric pressure and setting the pressure in the processing tank to a higher pressure than the atmospheric pressure, according to claim 1. Method of manufacturing cylindrical capacitors.