JPH058848B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field 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. 5, 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 the capacitance is taken at the opposing portions of both electrodes 2 and 3, as shown in the figure.
This outer electrode 3 is generally extended to one end of the porcelain element 1, and the internal electrode 2 is generally extended from the other end surface of the porcelain element 1 to the outer surface in order to form an extraction electrode portion 9.

In such cylindrical capacitors, Ni, Cu
When forming inner and outer surface electrodes using electrodes such as (plated electrodes), the following manufacturing method was conventionally used.

That is, as shown in FIG. 6A, first, a metal film 6 of Ni, Cu, or the like is formed on the inner and outer surfaces of the cylindrical porcelain body 1 by means such as electroless plating. Next, as shown in FIG. 6B, one end of the porcelain element 1 is held with a suitable holder 7, and the rotating pin 8 with the etching resist 4 attached thereto is inserted into the porcelain element 1. By applying an etching resist 4 to a portion of the inner surface of the element body 1 where the inner surface electrode 2 is to be formed, a coating film 5 is formed.
(see FIG. 6C), and also form a coating film 5 of the etching resist 4 on the outer surface of the porcelain body 1 where the outer surface electrode 3 is to be formed by means of brush coating, roller coating, etc. Thereafter, this porcelain body 1 is immersed in an etching solution, and as shown in FIG.
An outer surface electrode 3 was formed. Further, the etching resist on the extraction electrode part 9 of the inner surface electrode 2 cannot be formed using the rotating pin 8, but can be formed at the same time as the etching resist formed on the outer surface electrode 3 using a roller (not shown) or the like. . Finally, these coating films are removed using a solvent or the like, and a cylindrical capacitor as shown in FIG. 5 is completed.

Problems to be Solved by the Invention However, the method of applying etching resist to the inner surface of the porcelain body 1 using a rotating pin as described above has the following problems. That is, when the etching resist 4 is applied to the inner surface of the porcelain element 1 using the rotating pin 8, the thickness of the coating film on the inner surface of the porcelain element 1 becomes uneven due to variations in the amount of etching resist deposited on the rotating pin 8. Also, the edge of the inner surface electrode 2 often becomes wavy as shown by the dashed line in FIG. 5 due to bleeding of the etching resist, making it difficult to form the desired inner surface electrode.

Furthermore, as shown in FIG. 7, a cylindrical porcelain element 1
has a bottom portion 1a, and if it is desired to form an inner surface electrode on the inner surface of the bottom portion 1a, it is necessary to apply an etching resist to the inner surface of the bottom portion 1a as well.
However, in this case, it is difficult to apply the etching resist to the corner 1c of the inner surface of the porcelain body 1, so that the etching resist coating 5a applied to the inner surface of the bottom 1a and the inner peripheral surface of the porcelain body 1 are difficult to apply. There is a risk that the etching resist coating 5b will separate and the inner surface electrode formed after etching will be electrically disconnected at the corner 1c, causing a so-called electrode breakage phenomenon.

When applying etching resist using the rotating pin 8, if the inner diameter of the porcelain body 1 changes, the rotating pin 8 must be replaced with a corresponding outer diameter, which requires replacement work and associated pin mounting position adjustment. The work is time consuming and reduces the operating rate.

In the method of applying the etching resist using the rotary pin 8, it is extremely difficult to perform multi-processing in which the etching resist is applied to the inner surfaces of a large number of porcelain bodies 1 at once, and an improvement in manufacturing efficiency cannot be expected.

The etching resist application method using the rotary pin 8 cannot be applied when the porcelain body 1 has a rectangular tube shape other than a cylindrical shape.

There were other problems.

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

Means for Solving the Problems In order to achieve the above object, the manufacturing method of the present invention provides an etching resist bath in a pressure-adjustable processing tank, and in this processing tank, the etching resist bath is coated with a metal film, and one end of the etching resist bath is coated with a metal film. The other end opening of the blind cylindrical porcelain body is immersed in the etching resist bath, and the pressure inside the treatment tank is adjusted to be higher than the pressure inside the porcelain body. It is characterized by applying an etching resist to the inner surface of the porcelain body.

Effect According to the above manufacturing method, the other open end of the porcelain element whose one end is blind is immersed in a bath of etching resist, and after the open end is closed by the etching resist bath, the porcelain body is treated. When the air pressure inside the tank (air pressure outside the porcelain element) is made higher than the air pressure inside the porcelain element, the difference in pressure causes the etching resist to be pushed up from the open end of the porcelain element into the interior of the porcelain element.

Therefore, the inside of the magnetic body is filled and coated with etching resist up to the area where the etching resist is pushed up. In this case, the height to which the etching resist 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 the pressure difference in the processing tank is adjusted to compensate for the pressure difference. By keeping the pressure constant, whether the inner diameter of the porcelain body is large or small, the etching resist can be pushed up and filled to a certain height on the porcelain body, and if the pressure difference is adjusted, It is also possible to increase or decrease the coating area of the coating film on the inner surface of the porcelain body.

Note that "one end of the porcelain element is blind" refers to cases where one end of the porcelain element with both ends open is closed with another jig, etc., or when the porcelain element itself has a cylindrical shape with a bottom. It includes both.

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

FIGS. 1A to 1D are explanatory diagrams sequentially illustrating one embodiment of the manufacturing method of the present invention. First, as shown in FIG. A metal film 6 of Cu, Ag, etc. is formed by, for example, an electroless plating method or a dipping method. Next, as shown in FIG. Etching resist 4 provided in processing tank 12
Place it on top of the bath. Then, the inside of the processing tank 12 is degassed using a vacuum pump (not shown) or the like to reduce the pressure to a predetermined pressure. Although the number of porcelain bodies 1 held by the holding plate 11 is only one in the illustration, it is desirable to have a large number of them from the viewpoint of mass production.

When the pressure inside the processing tank 12 is completely reduced, the opening 1b side of the porcelain body 1 is immersed in the etching resist 4 bath, as shown in FIG. The depth of immersion is adjusted to the length required for the extraction electrode section.

When the other end of the porcelain body 1 is immersed in this way, the air pressure outside the porcelain body 1 (that is, the air pressure inside the processing tank 12) acts on the bath surface of the etching resist 4.
and the atmospheric pressure inside the porcelain body 1 are equal, and both are lower than atmospheric pressure. If no lead electrode is formed, the other end surface of the ceramic body 1 may be placed in contact with the bath surface of the etching resist 4.

Next, as shown in FIG. It is pushed up into the interior of the porcelain element 1 and is filled and coated on the inner surface of the porcelain element 1.

In this case, the height to which the etching resist 4 is pushed up is determined depending on the pressure difference between the inside and outside of the porcelain body 1, regardless of the inner diameter of the porcelain body 1. , by adjusting the reduced pressure and setting the pressure difference to a level that can push the etching resist 4 up to a height corresponding to the required dimensions of the inner electrode, the etching resist 4 can always be etched regardless of whether the inner diameter of the porcelain body 1 is large or small. The etching resist 4 is pushed up to a height corresponding to the dimensions of the inner electrode. Therefore, by changing the degree of degassing and depressurization of the initial treatment tank 12 to adjust the pressure difference and by changing the height at which the etching resist 4 is pushed up, the etching resist coating area on the inner surface of the porcelain body 1 can be increased. It is also possible to increase or decrease it arbitrarily.

When the pushing up of the etching resist 4 is completed, the inside of the processing tank 12 is degassed and depressurized again as shown in Figure E, so that the air pressure outside the porcelain body 1 is equal to or slightly lower than the air pressure inside the porcelain body 1. When the pressure is low, excess etching resist pushed up inside the porcelain body 1 returns to the etching resist bath, forming a coating film 5 on the inner surface of the porcelain body 1. Note that this step may be performed with the ceramic body 1 lifted above the etching resist 4. Next, as shown in FIG.
is formed.

Thereafter, although not shown, a coating film 5 of etching resist is also formed on the outer surface of the porcelain body 1 in an area corresponding to the size of the required outer surface electrode by appropriate means such as brush coating or roller coating.

Then, this porcelain body 1 is immersed in an etching solution 13 as shown in FIG. is completed.

The coating film 5 for the inner surface electrode formed as described above is
The pushed up etching resist 4 is the porcelain body 1
It is formed by being evenly and sufficiently adhered to the entire circumference of the inner surface. Moreover, if the pressure difference between the inside and outside of the porcelain body 1 is constant, the height at which the etching resist 4 is pushed up will always be constant, and the coating film 5
The upper edge of the electrode is no longer undulating, the coating area is always constant, and it has the shape and dimensions necessary to obtain the desired inner electrode.

In addition, the second degassing and depressurization operation to remove excess etching resist 4 from the porcelain body 1 is performed when the etching resist 4 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 etching resist inside is naturally discharged, it is not necessary to carry out this step.

Finally, by removing the coating film 5 with a solvent or the like, inner electrodes and outer electrodes are formed on the ceramic body 1, and a cylindrical capacitor as shown in FIG. 5 is completed.

Further, in the above embodiment, the etching resist 4 is applied by a method of reducing the pressure inside the tank and then returning the pressure to form the coating film 5.
After the porcelain element 1 is immersed in the etching resist 4 bath, the inside of the porcelain element 1 is pressurized to create an air pressure difference between the inside and the outside of the porcelain element. It goes without saying that the present invention can also be carried out by a method in which the inner surface of the porcelain body 1 is filled with the etching resist 4 and then the pressure is returned to normal pressure.

Furthermore, porcelain element 1 according to the manufacturing method of the present invention
can be immersed in the treatment tank with one end closed.
A porcelain body 1 having a bottom portion is manufactured in the same manner. FIG. 2 shows a porcelain body 1 having a bottom portion 1a.
2 shows an example in which the inner surface electrode 2 is also formed on the inner surface of the bottom portion 1a. Since the process of reducing and restoring the pressure inside the tank is the same as in the above embodiment, the processing tank 12 with adjustable pressure similar to that shown in FIG.
However, the treatment tank is omitted in the figure, and only the ceramic body 1 coated with the metal film 6 and the etching resist 4 are shown. First, the pressure inside the tank is reduced (Figure A), the lower end opening 1b of the porcelain body 1 is immersed in the etching resist 4 bath (Figure B), and then the pressure inside the tank is restored (Figure C). The steps up to this point are shown in Figure 1 A, B,
Since it is exactly the same as C, detailed explanation will be omitted.
The procedure after pressure restoration will be explained. When the pressure inside the tank is restored, the etching resist 4 is pushed up inside the porcelain body 1 due to the pressure difference between the inside and outside of the porcelain body 1. At this time, the top surface of the etching resist 4 touches the bottom of the porcelain body 1. It has not reached the inner surface of 1a. That is, air 14 remains between the upper surface of the etching resist and the inner surface of the bottom portion 1a of the porcelain body 1, which is determined by the value of the reduced pressure at the time of reducing the pressure. Also, the pressure reduction value during this pressure reduction is preferably 50 to 60 mm.
Set to Hg. In other words, if the reduced pressure value is lower than 50 mmHg, the bubbles contained in the etching resist bath will grow to a large extent, causing a waving phenomenon on the etching resist bath surface, and the edge shape of the extraction electrode portion 9 (see FIG. 5) will change. Because it will get worse.

However, at the same time as the pressure inside the tank was restored,
When pressurized at a pressure of 5,000 mmHg, preferably 2,000 mmHg, the inside of the porcelain body 1 is exposed to a portion where the etching resist 4 contacts the inner surface of the bottom portion 1a of the porcelain body 1, although granular air 14 remains, as shown in Figure D. It is pushed even higher. When this pressurized state is maintained for 5 to 30 seconds, the etching resist 4
Due to the wettability of the etching resist 4, the etching resist 4 pushes away the granular air 14 as shown in FIG.
a It begins to wrap around the inside.

In this way, the etching resist adheres to the entire bottom inner surface 1a of the porcelain body.

Next, the pressure inside the tank is reduced again, and the etching resist 4 that had been pushed up inside the porcelain body is lowered to its original level as shown in the figure. The reduced pressure value at this time is preferably the same as the reduced pressure value in the first step or about 10 mmHg smaller than that. Once the pressure reduction is completed, the porcelain body 1 is raised. Next, as in the previous embodiment, an etching resist is applied to the outer surface of the ceramic body 1 by appropriate means in a portion corresponding to the region where the outer surface electrode is to be formed. Thereafter, as shown in the figure, the ceramic body 1 is immersed in an etching solution to remove the portions of the metal film 6 not covered with the etching resist, thereby forming inner and outer electrodes. The cylindrical capacitor thus manufactured is as shown in FIG. As can be seen from the figure, a coating film is continuously formed from the inner peripheral surface of the porcelain element 1 to the entire bottom part, and the coating film 5b applied to the inner peripheral surface of the porcelain element 1 and the inner surface of the bottom part 1a are The applied coating film 5a is always electrically connected, and electrode breakage does not occur.

Also, in the embodiment shown in FIG. 2 above, the method for creating a pressure difference is to immerse the opening 1b of the porcelain body 1 in an etching resist bath and apply pressure while the inside of the bath is kept at normal pressure. Of course, it may also depend on. In this case, the etching resist can be applied to the desired depth from the opening 1b on the inner surface of the porcelain body 1 depending on the degree of pressure applied, and the etching resist can also be applied to the inner surface of the bottom portion 1a only by applying pressure. can do.

In the example shown in Fig. 2, etching resist was also applied to the inner surface of the bottom in order to obtain a large capacity cylindrical capacitor, but by adjusting the reduced pressure, etching resist was applied to the inner surface of the bottom as shown in Fig. 4. You are free to choose not to apply resist. In this case, the problem of air voids as shown in FIG. 2 does not occur.

In each of the above embodiments, the inner and outer electrodes of the porcelain body are simultaneously formed by etching, but it is also possible to form the outer electrodes in advance or to form them again after forming the inner electrodes by etching. You can do it like this. In this case, the outer electrode may be formed from a paste such as Ag.

Effects of the Invention As detailed above, according to the method of manufacturing a cylindrical capacitor according to the present invention, the coating film formed on the inner surface of the porcelain body by the etching resist does not have uneven undulating edges. Since its area, dimensions, thickness, etc. are always constant, the area of the inner electrode formed by etching is always constant, and the production yield is also improved by about 10 to 20%.

Moreover, when forming this 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 length of the porcelain body Since it is possible to form a coating film with a predetermined inner electrode size even if the inner diameter and length of the porcelain body differ, it is difficult to replace and adjust the rotating pin etc. every time the inner diameter or length of the porcelain element differs. This eliminates the need for any additional work.

Furthermore, since it is a dipping method that does not use a rotating pin, the etching resist can be evenly and uniformly applied not only to cylindrical porcelain bodies but also to rectangular cylindrical porcelain bodies. .

Furthermore, according to the manufacturing method of the present invention, it is possible to perform multi-processing in which etching resist is applied to a large number of porcelain bodies at the same time, so that remarkable effects such as a dramatic improvement in productivity can be obtained.

[Brief explanation of the drawing]

1 to 1 are explanatory diagrams sequentially explaining a method for manufacturing a cylindrical capacitor according to an embodiment of the present invention, and FIG.
Figures 1 to 2 are cross-sectional views of cylindrical capacitors according to other embodiments of the present invention, Figure 3 is a sectional view of an example of a cylindrical capacitor with a bottom, and Figure 4 is a sectional view of another example of a cylindrical capacitor with a bottom. Figure 5 is a cross-sectional view of a cylindrical capacitor with open ends, Figure 6 is a cross-sectional view of essential parts showing an example of a conventional manufacturing method, and Figure 7 is a conventional manufacturing method of a bottomed cylindrical capacitor. FIG. 3 is a cross-sectional view for explaining the problem. 1...Porcelain body, 4...Etching resist,
6...Metal film.

Claims (1)

[Scope of Claims] 1. An etching resist bath is provided in a processing tank whose pressure can be freely adjusted, and in this processing tank, the other end of a cylindrical porcelain element coated with a metal film and having one end blind is opened. The etching resist is applied to the inner surface of the porcelain element by immersing the part in the etching resist bath and adjusting the atmospheric pressure in the treatment tank to be higher than the atmospheric pressure inside the porcelain element. Method of manufacturing cylindrical capacitors. 2. The tube according to claim 1, wherein the etching resist 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 the pressure inside the processing tank to atmospheric pressure. Method of manufacturing type capacitors. 3. The cylinder according to claim 1, wherein the pressure inside the porcelain body is atmospheric pressure, and the pressure inside the processing tank is set higher than atmospheric pressure to apply an etching resist to the inner surface of the porcelain body. Method of manufacturing type capacitors.