JPH058849B2 - - 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 outer electrodes thereof.

Conventional technology As shown in FIG. 2, 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.
The outer electrode 3 is generally extended to one end of the porcelain element 1, and the inner 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 7.

By the way, in the above-mentioned cylindrical capacitor, when forming the inner and outer electrodes with plated electrodes of Ni, Cu, etc., conventionally, the capacitor is manufactured by the following method.

That is, as shown in FIG. 3A, first, the porcelain element 1 is
A metal film 6 of Ni, Cu, or the like is formed on the entire surface by electroless plating or the like. Next, as shown in FIG. 3B, the transfer roller 8 to which the etching resist 4 is attached is used to apply the etching resist 4 to the portions of the outer surface of the porcelain body 1 where the outer surface electrode 2 and the extraction electrode portion 7 are to be formed. The coating is applied to form coating films 5a and 5b. Particularly in this case, it is convenient to wrap the etching resist 4 around the other end surface of the porcelain body 1 to form a coating film. Further, there are cases where, for example, brush painting or spatula painting is performed without using the transfer roller 8.

Next, a coating film 5c of etching resist is also formed on the inner surface of the ceramic body 1 in the area where the internal electrodes 3 are to be formed, using, for example, a rotating pin (not shown).

Thereafter, this porcelain body a is immersed in an etching solution, and as shown in FIG. The electrode 2, inner surface electrode 3, and extraction electrode 7 are formed, and finally these coating films 5a, 5b, and 5c are removed using a solvent or the like. A cylindrical capacitor as shown in FIG. 2 is then manufactured.

Problems to be Solved by the Invention However, the method of applying an etching resist for forming the external electrode as described above has the following problems. That is, the etching resist 4 is etched using the transfer roller 8.
When coating the outer surface of the porcelain body 1, if there are variations in the amount of etching resist deposited on the transfer roller 8, the edges of the coating films 5a, 5b often become wavy. It is not easy to form the electrode 3 and the extraction electrode 7 in the shape and size, and in extreme cases, the coating film 5
A and 5b may be partially connected. Therefore, the metal film 6 that is not covered with the coating films 5a and 5b
Even if the exposed portion is etched, it is difficult to form the desired outer surface electrode 3.

When applying the etching resist 4 to the outer surface of the porcelain body 1 using the transfer roller 8 as described above, the transfer roller 8 must be constantly checked so that the amount of etching resist adhered to the transfer roller 8 does not fluctuate. It is necessary to frequently stop and clean the transfer roller 8, and these adjustment operations take time and effort, resulting in a decrease in operating efficiency.

In the method of applying etching resist using the transfer roller 8, it is extremely difficult to perform multi-processing in which the etching resist 4 is applied to the outer surface 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 transfer roller 8 is difficult to apply to a rectangular tube shape other than a cylindrical shape of the porcelain body 1.

The etching resist coating method using a brush or a spatula has the above-mentioned problems and cannot be expected to be mass-produced.

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 external electrodes.

Means for Solving the Problems In order to achieve the above object, the manufacturing method of the present invention provides a method for manufacturing a cylindrical porcelain element coated with a metal film and having an opening at both ends sealed. By placing the other end in contact with the etching resist bath surface, making the external pressure of the porcelain body lower than the internal pressure, and then immersing the porcelain body in the etching resist bath, The gist of this method is to apply an etching resist to the outer surface of the porcelain body.

According to the above manufacturing method, the opening at one end of the porcelain element is sealed and the other end of the porcelain element is placed in contact with the bath surface of the etching resist, so that the air pressure outside the porcelain element is changed from the air pressure inside the porcelain element. When the porcelain element is immersed in an etching resist bath after the pressure is lowered, the etching resist is prevented from penetrating into the porcelain element due to the high atmospheric pressure inside the porcelain element. Therefore, no coating film is formed on the inner surface of the porcelain element, and the etching resist adheres to only one end surface and outer surface of the porcelain element to form a coating film. The area on which the etching resist is adhered to the outer surface of the porcelain body is determined by the depth of immersion of the etching resist of the porcelain body into the bath.

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

FIGS. 1A to 1F are explanatory diagrams sequentially explaining one embodiment of the manufacturing method (electrode forming method) of the present invention. First, as shown in FIG. A metal film 6 of Ni, Cu, Ag, etc. is formed on the inner and outer surfaces of the body 1 by, for example, an electroless plating method or a dipping method.

Next, as shown in FIG. 4B, the porcelain body 1 is held and sealed by holding the other end on a holding plate 11 with the opening 1b of one end facing downward, and is placed in a processing tank 12 whose pressure can be freely adjusted. Etching resist 4 provided inside
Place it on top of the bath. The number of porcelain bodies 1 held by the holding plate 11 is only one in the illustration, but from the viewpoint of mass production, it is desirable to have a large number of porcelain bodies 1.

Next, as shown in FIG. 3C, the opening 1b of the porcelain body 1 is arranged so as to be in contact with the bath surface of the etching resist 4. Then, the inside of the processing tank 12 is evacuated using a vacuum pump (not shown) or the like to reduce the pressure to a predetermined pressure, so that the air pressure outside the porcelain element 1 is lower than the air pressure inside the porcelain element 1.

Next, with this pressure difference applied, the porcelain body 1 is exposed to an etching resist 4 as shown in FIG.
immerse in a bath of 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 such a pressure difference, the atmospheric pressure inside the porcelain element 1 is high, so that the etching resist 4 is prevented from entering the porcelain element 1, and only one end surface and the outer surface of the porcelain element 1 are etched. Resist 4 is attached. Therefore, when the porcelain body 1 is lifted out of the etching resist bath 4 as shown in FIG.
A coating film 5 of etching resist is formed from the outer surface of the porcelain body 1 to one end surface.

When the coating film 5 of the etching resist for forming the external electrode is formed in this way, the etching resist 4 adheres uniformly and sufficiently over the entire periphery of the immersed portion of the outer surface of the porcelain body 1, and the film thickness becomes almost constant. .
In addition, the area of the coating film 5 is determined by the depth of immersion, so it is always constant, and the upper edge is not undulated, so there is a clear gap between the inner electrode 2 and the extraction electrode part 7. (See Figure 2).

Next, although not shown, a coating film 5 of etching resist for forming inner electrodes is also formed on the inner surface of the porcelain body 1 using an appropriate means such as a rotary pin (see FIG. 1 for the formation method).

After the coating film 5 of the etching resist has been formed on the porcelain body 1 in this way, in the next etching process, the porcelain body 1 is immersed in an etching solution 10 as shown in FIG. By etching the unetched exposed portions of the metal film 6 and then removing the coating film 5 with a solvent or the like, inner electrodes 2 and outer electrodes 3 are formed on the inner and outer surfaces of the porcelain body 1.

It goes without saying that the present invention is not limited to the embodiments described above. For example, in the state shown in FIG. Even if the air in the treatment tank 12 is released and returned to atmospheric pressure, a pressure difference is generated between the inside and outside of the porcelain body 1, and the object of the present invention can be achieved.
In this case, the degree of pressurization is sufficient as long as the etching resist 4 does not penetrate into the inside of the porcelain body when the porcelain body 1 is immersed in the bath of the etching resist 4. Specifically, the degree of pressure is lower than atmospheric pressure. It is also preferable to apply pressure to a high pressure of about 100 mmHg.

Further, in the above embodiment, the etching resist coating 5 is formed on the inner and outer surfaces of the porcelain body 1 and then etched, but this is not necessarily the case. Furthermore, the inner surface electrode may be formed by a completely different method than etching.

Effects of the Invention As detailed above, according to the method for manufacturing a cylindrical capacitor of the present invention, the edge of the etching resist coating film for the outer electrode does not become uneven and wavy, and the area of the coating film Since the shape, dimensions, etc. are always constant, there are almost no defects such as capacitance defects due to variations in the area of the outer electrode formed by etching, and defective products due to short circuits between the outer electrode and the extraction electrode part of the inner electrode. No longer occurs, production yield is 10
Improved by ~20%.

In addition, since a transfer roller is not used as in the past, there is no need to check or clean it, and the operating rate is greatly improved.

Furthermore, since the immersion method is employed, it is possible to form an etching resist coating having an even and uniform thickness not only on cylindrical porcelain bodies but also on 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 multiple porcelain bodies at the same time, resulting in remarkable effects such as a dramatic improvement in productivity. .

[Brief explanation of the drawing]

1A to 1F are explanatory diagrams sequentially explaining a method for manufacturing a cylindrical capacitor according to an embodiment of the present invention, and FIG.
The figure is a cross-sectional view of a cylindrical capacitor, and FIG. 3 is a cross-sectional view of essential parts explaining an example of a conventional manufacturing method. 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, one end opening of a cylindrical porcelain element coated with a metal film and having an opening at both ends is sealed. In this state, the other end of the porcelain element is placed in contact with the bath surface of the etching resist, and the air pressure outside the porcelain element is lower than the internal air pressure;
A method for manufacturing a cylindrical capacitor, which comprises applying an etching resist to the outer surface of the porcelain element by immersing the porcelain element in an etching resist bath. 2. The present invention is characterized in that the pressure inside the processing tank is adjusted to atmospheric pressure, and the pressure inside the porcelain body is set higher than the atmospheric pressure to apply an etching resist to the outer surface of the porcelain body. A method for manufacturing a cylindrical capacitor according to item 1. 3. Claims characterized in that the pressure inside the porcelain body is atmospheric pressure, and the pressure inside the processing tank is adjusted to a pressure lower than the atmospheric pressure to coat the outer surface of the porcelain body with an etching resist. 2. A method for manufacturing a cylindrical capacitor according to item 1.