JPS6384006A - Manufacture of cylindrical capacitor - Google Patents

Abstract

(57) [Abstract] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] Kokurijokigokudanbun! The present invention relates to a method for manufacturing a cylindrical capacitor, and particularly to a method for forming inner electrodes thereof.

Conventional ■ Return A conventional general cylindrical capacitor has inner electrodes 2 on the inner and outer surfaces of a cylindrical porcelain body 1, respectively, as shown in Fig. 5.
By forming the outer surface electrode 3, both electrodes 2,
As shown in the figure, the outer electrode 3 extends to one end of the porcelain body 1, and the inner electrode 2 forms the lead electrode part 9. Therefore, it is common to extend from the other end surface of the porcelain body 1 to the outer surface.

In such a cylindrical capacitor, when forming the inner and outer electrodes using electrodes (plated electrodes) of Ni, CU, etc., the following manufacturing method has conventionally been used.

That is, as shown in FIG. 6(a), first, the cylindrical porcelain element 1 is
A metal film 6 of Ni, Cu, or the like is formed on the inner and outer surfaces of the substrate by electroless plating or the like. Next, as shown in Figure 6 (b),
One end of this porcelain body 1 is held with a suitable holder 7, and a rotary bottle 8 with etching resist 4 attached is placed on the porcelain body 1.
The etching resist 4 is applied to the inner surface of the porcelain element 1 where the inner electrode 2 is to be formed, thereby forming a coating film 5 (see FIG. 6(c)). A coating film 5 of the etching resist 4 is also formed on the outer surface of the body 1 at the portion where the outer surface electrode 3 is to be formed by brush coating, roller coating, etc., and then this porcelain body 1 is immersed in an etching solution. However, as shown in FIG. 6(C), the inner surface electrode 2 and the outer surface electrode 3 were formed by etching the portion of the metal film 6 that was not covered with the etching resist coating.

Further, the etching resist on the extraction electrode part 9 of the inner surface electrode 2 cannot be formed by the rotating pin 8, but by the roller (
(not shown) or the like at the same time as the etching resist formed on the outer surface electrode 3.

Finally, these coating films are removed using a solvent or the like, and a cylindrical capacitor as shown in FIG. 5 is completed.

However, as mentioned above, by using a rotating bottle, the porcelain element 1
The method of applying etching resist to the inner surface 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 bottle 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 in the rotating bottle 8. In many cases, the edge of the inner surface electrode 2 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, the cylindrical porcelain body 1 is
a, and if it is desired to form an inner surface electrode also on the inner surface of the bottom portion 1a, it is necessary to apply an etching resist also to the inner surface of the bottom portion 1a. However, in this case, it is difficult to apply the etching resist to the corner IC on the inner surface of the porcelain body 1, and therefore, the etching resist coating 5a applied to the inner surface of the bottom portion 1a and the etching resist coating 5a applied to 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, it is necessary to replace it with a rotating bottle 8 with an outer diameter that corresponds to the change, and the replacement work and the associated pin mounting position must be changed. Adjustment work is time-consuming and reduces operating efficiency.

(2) In the method of applying etching resist using the rotating pin 8, multi-processing of applying etching resist to the inner surfaces of a large number of porcelain bodies 1 at one time is extremely difficult, and no improvement in manufacturing efficiency can be expected.

■In the etching resist application method using rotating pin 8,
This method cannot be applied when the porcelain body 1 has a rectangular tube shape other than a cylindrical shape.

There were problems such as.

SUMMARY OF THE INVENTION An object of the present invention is to solve these conventional problems and 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.

In order to achieve the above object, the manufacturing method of the present invention involves making one end of a cylindrical porcelain element coated with a metal film blind and immersing the other end in an etching resist bath. The gist of this method is to apply an etching resist to the inner surface of the porcelain element by making the air pressure outside the porcelain element higher than the air pressure inside the porcelain element acting on the bath surface of the etching resist.

According to the manufacturing method described above, the open end of the porcelain element whose one end is blind is immersed in an etching resist bath, and the air pressure outside the porcelain element acting on the surface of the etching resist bath is transferred to the porcelain element. When the pressure is higher than the atmospheric pressure inside the body, the difference in pressure causes the etching resist to be pushed up into the interior of the porcelain element through the opening at the other end of the porcelain element.

Therefore, the inner surface of the porcelain element is filled with the etching resist up to the point where the etching resist is pushed up, and at the same time, the etching resist is also attached to the other end surface of the porcelain element and the outer surface near the other end. Ru. 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 if the pressure difference is held constant, the inner diameter of the porcelain body will increase. Even if the etching resist is small or small, it is possible to push up and fill the etching resist to a certain height on the inner surface of the porcelain body, and by adjusting the pressure difference, you can increase or decrease the coating area of the coating on the inner surface of the porcelain body. It is also possible to do so.

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

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

FIGS. 1(A) to 1(G) are explanatory diagrams sequentially explaining one embodiment of the manufacturing method of the present invention. First, as shown in FIG. 1(A), a porcelain element body formed with openings at both ends A metal film 6 of Ni, Cu%Ag, etc. is formed on the entire surface of the substrate 1 by, for example, an electroless plating method or a dipping method. Next, the porcelain body 1
is held on the holding plate 1) with the opening 1b at the other end facing downward and the opening at one end is sealed, as shown in FIG. The etching resist 4 is placed on the bath provided in the etching resist 4. 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 on the holding plate 1) is only one in the illustration,
From the point of view of mass production, it is desirable to have a large number of these.

When the pressure inside the processing tank 12 is completely reduced, the opening 1b side of the ceramic 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 atmospheric pressure outside the porcelain body 1 acting on the bath surface of the etching resist 4 (that is, the atmospheric pressure inside the processing bath 12) and the atmospheric pressure inside the porcelain body 1 are equal to each other. Equally, both have lower pressure 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. 4D, when outside air is introduced into the processing tank 12 to restore the pressure inside the processing tank 12 to atmospheric pressure, a pressure difference is created between the inside and outside of the porcelain body 1, and the etching resist 4 is pushed up into the inside of the porcelain element 1 and filled into 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 degassing and depressurization of the porcelain body 1 and setting it to a pressure difference that can push up the etching resist 4 to a height corresponding to the required dimensions of the inner electrode, it is possible to adjust the pressure difference even if the inner diameter of the porcelain element 1 is large or small. In this case, the etching resist 4 is always 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 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 adjusted as desired. It is also possible to increase or decrease the amount.

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 FIG. Alternatively, if the pressure is slightly lower, the excess etching resist pushed up inside the porcelain element 1 is scraped off, and a coating film 5 is formed on the inner surface of the porcelain element 1. Note that this step may be performed with the ceramic body 1 lifted above the etching resist 4. Next, as shown in the figure (f), the porcelain element 1
When it is lifted out of the etching resist bath 4, a coating film 5 of etching resist is formed from the inner surface of the porcelain body 1 to the outer surface of the opening 1b.

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. The membrane is completed.

In the inner electrode coating film 5 formed as described above, the etching resist 4 that has been pushed up is evenly and sufficiently adhered to the entire circumference of the inner surface of the porcelain body 1.

Furthermore, if the pressure difference between the inside and outside of the porcelain body 1 is kept constant, the height at which the etching resist 4 is pushed up will always be constant, and the upper edge of the coating film 5 will no longer be undulating.
The coating area is always constant and has the shape and dimensions necessary to obtain the desired inner electrode.

In addition, the second degassing and depressurization operation to remove the excess etching resist 4 from the porcelain body 1 is necessary if the etching resist 4 inside the porcelain body 1 cannot be naturally discharged due to surface tension or the like. However, porcelain element 1
If the inner diameter of the etching resist is large and the etching resist inside is naturally discharged, there is no need to do this.

Finally, by removing the coating film 5 with a solvent or the like,
An inner electrode and an outer electrode 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 reducing the pressure inside the tank and then returning the pressure to form the coating film 5. However, the inside of the processing tank 12 is initially set to atmospheric pressure, After the body 1 is immersed in the bath of the etching resist 4, the inside of the processing bath 12 is pressurized to create an air pressure difference between the inside of the porcelain body and the outside of the porcelain body, and the etching resist 4 is applied to the inner surface of the porcelain body 1. It goes without saying that the present invention can also be carried out by a method of filling the tank and then returning the pressure to normal pressure.

Furthermore, the porcelain element 1 according to the manufacturing method of the present invention may be immersed in the treatment tank with one end closed (although the porcelain element 1 having a bottom may be manufactured in the same manner. This shows an example in which an inner surface electrode 2 is also formed on the inner surface of the bottom portion 1a of a porcelain body 1 having a bottom portion 1a.The pressure inside the tank is reduced and restored in the same manner as in the above example. Therefore, a pressure-adjustable processing tank 12 similar to that shown in FIG. 1 is used, but the processing tank is omitted in the figure, and only the porcelain body l coated with the metal film 6 and the etching resist 4 are shown.

First, the inside of the bath is depressurized (Fig.
(b)), then restore the pressure inside the tank (Figure (c)). Since the steps up to this point are exactly the same as those in FIGS. 1(a), (b), and (c), a detailed explanation will be omitted, and the steps 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, but at this time, the top surface of the etching resist 4 touches the inner surface of the bottom 1a of the porcelain body 1. It has not been reached. 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. Further, the pressure reduction value during this pressure reduction is preferably set to 50 to 60 wHg. In other words, when the reduced pressure value is set to 50 mmHg or less, the bubbles contained in the etching resist bath 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) changes. Because it will get worse.

Therefore, at the same time as repressurizing the inside of the tank,
When pressurized at a pressure of 1 g, preferably 20001 ml, the inside of the porcelain body 1 remains as shown in Figure (d), although the granular air 14 remains, the etching resist 4
is further pushed up to the point where it contacts the inner surface of the bottom portion 1a of the porcelain element l. When this pressurized state is maintained for 5 to 30 seconds, the wettability of the etching resist 4 increases as shown in Figure (H).
As shown in FIG.
It pushes away and wraps around the inner surface of the bottom portion 1a.

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 FIG. 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 step (g), the porcelain body 1 is immersed in an etching solution to remove the metal film 6 in the portion not covered with the etching resist.
Form an inner surface electrode and an outer surface electrode.

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 circumferential surface of the porcelain body 1 to the entire bottom part,
The coating film 5b applied to the inner circumferential surface of the porcelain body 1 and the coating film 5a applied to the inner surface of the bottom portion 1a are 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 is also possible to do so. In this case, depending on the degree of pressurization, the opening 1b on the inner surface of the porcelain element 1
The etching resist can be applied to the desired depth, and the etching resist can also be applied to the inner surface of the bottom portion 1a only by applying pressure.

In the embodiment 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.
By adjusting the reduced pressure, it is also possible to avoid applying the etching resist to the inner surface of the bottom, as shown in FIG. 4. In this case, the problem of air voids as shown in FIG. 2 does not occur.

In each of the above-mentioned 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. In this case, the outer electrode may be formed from a paste such as Ag.

As detailed above, according to the method for manufacturing a cylindrical capacitor according to the present invention, the edges of the coating film formed on the inner surface of the porcelain body by the etching resist are uneven and wavy. Since the area, dimensions, thickness, etc. are always constant, the area of the inner electrode formed by etching is always constant, and the production yield is 10~20%.
% improvement.

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 no longer necessary to replace or adjust the rotating pin etc. every time the inner diameter or length of the porcelain element differs. No additional work is required.

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.

Moreover, 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 a remarkable effect such as a dramatic improvement in productivity can be obtained.

[Brief explanation of the drawing]

Figures 1 (a) to (g) are explanatory diagrams sequentially explaining a method for manufacturing a cylindrical capacitor according to one embodiment of the present invention, and Figures 2 (a) to (g) are other embodiments of the present invention. 3 is a sectional view showing an example of a cylindrical capacitor with an eave, FIG. 4 is a sectional view showing another example of a cylindrical capacitor with an eave,
Figure 5 is a cross-sectional view of a cylindrical capacitor with openings at both ends, Figure 6 is a cross-sectional view of essential parts showing an example of a conventional manufacturing method, and Figure 7 explains problems with the conventional manufacturing method of a bottomed cylindrical capacitor. FIG. 1... Porcelain body, 4... Etching resist, 6...
...Metal film.

Claims (3)

[Claims] (1) One end of a cylindrical porcelain body coated with a metal film is made blind and the other end is immersed in an etching resist bath, and the air pressure outside the porcelain body acting on the bath surface of the etching resist is transferred to the inside of the porcelain body. A method of manufacturing a cylindrical capacitor, characterized in that an etching resist is applied to the inner surface of the porcelain body by applying a pressure higher than the atmospheric pressure of . (2) 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 setting the pressure outside the porcelain body to atmospheric pressure. 1) A method for manufacturing a cylindrical capacitor as described in item 1). (3) The etching resist is applied to the inner surface of the porcelain body by setting the pressure inside the porcelain body to atmospheric pressure and setting the pressure outside the porcelain body to a higher pressure than atmospheric pressure. 1) A method for manufacturing a cylindrical capacitor as described in item 1).