JPH0611019B2 - Manufacturing method of cylindrical porcelain capacitor - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for manufacturing a cylindrical ceramic capacitor.

[Conventional technology]

As shown in FIG. 9, the conventional cylindrical ceramic capacitor is
Electrodes 2 and 3 are provided on the inner and outer peripheral surfaces of a cylindrical porcelain element body 1 and are opposed to each other.

Since the external dimensions of this type of cylindrical porcelain capacitor are determined in advance by standards, it is required to obtain a higher electrostatic capacitance within the determined length and outer diameter. Generally, the capacitance of a capacitor is proportional to the facing area S of the electrodes and the relative permittivity ε of the dielectric, and inversely proportional to the thickness t of the dielectric sandwiched between the electrodes.

However, the electrode 2,
There is a limit to the expansion of the facing area S of 3. Further, there is a limit to reducing the thickness t of the porcelain body 1 in order to guarantee bending strength when the porcelain capacitor is mounted on the wiring board.

Therefore, for example, a porcelain capacitor as disclosed in Japanese Utility Model Publication No. 59-32116 has been proposed. In this porcelain capacitor, internal electrodes and dielectric layers are alternately laminated on the outer circumference of a cylindrical porcelain body, and a pair of internal electrodes formed to face each other with the dielectric layers sandwiched between External electrodes are formed so as to be led out to the end face side and connected to the internal electrodes at the end portions of the porcelain body.

Such a porcelain capacitor is manufactured by the following method. First, the process of applying a conductive paste on the outer periphery of a porcelain body, drying it, then applying a dielectric slurry, and drying is repeated an appropriate number of times. Then, the conductive paste and the dielectric slurry are fired. After that, external electrodes are formed on both end sides of the porcelain body, and insulating coating is applied to necessary portions.

[Problems to be solved by the invention]

However, in the conventional method of manufacturing a columnar ceramic capacitor, it is necessary to separately form an external electrode at the end of the ceramic body in addition to the internal electrode. Moreover, since it is difficult to completely expose the internal electrode pattern at the end of the porcelain body, after the firing process, when applying the conductive paste to the end of the porcelain body and baking to form the external electrode, the internal electrode And the conduction state of the external electrode is likely to be incomplete. Therefore, there is a problem in that a defective product in which a predetermined electrostatic capacity cannot be obtained is generated and the yield is low.

Therefore, in order to ensure the connection between the internal electrode and the external electrode, after the firing step, the end surface of the porcelain body is polished to surely expose the internal electrode to the end surface side of the porcelain body, and then the external electrode. Need to be formed.

However, in this case, the barrel polishing method used for collecting a large number of small chip components and polishing them at the same time not only grinds the end face but also the dielectric layer on the peripheral surface side at the same time.
It cannot be adopted. Therefore, it is necessary to individually polish the end faces of the small columnar chips, and this process requires many steps.

The present invention solves the above-mentioned problems in the conventional method for manufacturing a cylindrical ceramic capacitor, and it is not always necessary to separately form the external electrode in addition to the internal electrode. It is an object of the present invention to provide a method for manufacturing a cylindrical ceramic capacitor that can be reliably connected to its internal electrode without performing steps.

[Means for solving problems]

That is, in order to achieve the above object, in the present invention, except for the first end side of the cylindrical porcelain body 11, the conductive paste a is applied to the outer peripheral side of the porcelain body 11 and dried, Next, the dielectric slurry b is applied to the outer peripheral side of the porcelain body 11 except for both end sides thereof and dried, and then the porcelain body 11 is removed except for the second end side thereof. A step of applying the conductive paste a to the outer peripheral side of the body 11 and drying it, and then applying a dielectric slurry b to the outer peripheral side of the same porcelain body 11 except for both end sides, and drying. And a step of firing the conductive paste a and the dielectric slurry b.

[Action]

In the method of manufacturing a cylindrical ceramic capacitor according to the present invention, the conductive paste and the dielectric slurry b are alternately overlaid on the outer peripheral surface of the ceramic body 11. For this reason, when this is fired, thin and many dielectric layers 14, 14 ... and internal electrodes 15, 15 ..., 16, 16 ... Can be easily formed. Further, the coating thickness can be easily adjusted by adjusting the coating amount of the dielectric slurry b, and the thicknesses of the dielectric layers 14, 14 ... And the internal electrodes 15, 15 ,.

Further, the layers of the conductive paste a for forming the internal electrodes 15, 15, ..., 16, 16 ... Of each set are sequentially overcoated on the end side of the porcelain body 11 on which the dielectric slurry b is not applied. , Each set of internal electrodes 15, 15 ..., 16, 16 ...
Are integrated on the end side of the porcelain body 11. Therefore,
If the portion where the internal electrodes 15, 15, ..., 16, 16, ... Are integrated is exposed from the outermost dielectric layer 14, it can be used as it is as an external electrode. When an external electrode is separately provided, this internal electrode 15,
The portion where 15 ..., 16 and 16 ... Overlap enables reliable electrical connection with the external electrode.

〔Example〕

Next, with reference to FIGS. 1 to 8, an embodiment of the present invention will be described according to a manufacturing procedure of a cylindrical ceramic capacitor.

First, the cylindrical porcelain body 11 is prepared. The porcelain body 11 is obtained by kneading porcelain powder together with a binder, molding it into a cylindrical shape, and drying it. In addition,
The allotrope 11 is not limited to a non-sintered one, but may be one already sintered.

FIG. 8 shows an embodiment of the step of applying the conductive paste a and the dielectric slurry b on the outer peripheral surface of the porcelain body 11. The pin 22 rotatably attached to the conveyor belt 23 is inserted into the through hole of the porcelain body 11 to rotatably support the porcelain body 11. In this state, the porcelain body 11
Is conveyed in the longitudinal direction of the conveyor belt 23, and the outer peripheral surface thereof is brought into contact with the peripheral surface of the transfer roller 20.

The peripheral surface of the transfer roller 20 is coated with the conductive paste a, which is transferred to the outer peripheral surface of the porcelain body 11. The amount of the conductive paste a transferred to the outer peripheral surface of the porcelain element body 11, that is, the coating thickness, moves the marking plate 25 near the peripheral surface of the transfer roller 20, and the gap between the marking plate 25 and the transfer roller 20. Adjusted by changing.

Next, the porcelain body 11 is transported to the dryer 18 as the transport belt 23 travels, and the conductive paste a is dried therein.

Then, the outer peripheral surface of the porcelain element body 11 carried out from the dryer 18 is brought into contact with the peripheral surface of the transfer roller 21, and the dielectric slurry b is applied in the same manner as the conductive paste a. 8th
In the figure, 26 is a marking board. Then, the porcelain body 11 is conveyed to the dryer 19 and the dielectric slurry b is dried.

Hereinafter, this is alternately repeated so that the conductive paste a and the dielectric slurry b are alternately overlaid. Finally, these are fired to form the internal electrodes 15, 15, ..., 16, 16 ... And the dielectric layers 14, 14.

FIGS. 2 to 7 show an example of a process in which the conductive paste a and the dielectric slurry b are applied in manufacturing the cylindrical ceramic capacitor as shown in FIG.

First, as shown in FIG. 2, a conductive paste a serving as the internal electrode 15 is applied to a portion of the outer peripheral surface of the porcelain body 11 excluding the left end and dried. Next, as shown in FIG. 3, except for the right end portion of the porcelain body 11, the dielectric slurry b to be the dielectric layer 14 is applied and dried. Next, as shown in FIG. 4, except for the right end of the porcelain body 11, the internal electrode 16
Conductive paste a is applied and dried. next,
As shown in FIG. 5, except for both ends of the porcelain body 11,
The dielectric slurry b to be the dielectric layer 14 is applied and dried. Next, as shown in FIG. 6, except for the left end of the outer peripheral surface of the porcelain body 11, the conductive paste a that will become the internal electrodes 15 is applied and dried. Here, on the right end side of the porcelain body 11, the conductive paste a of the inner peripheral side layer to be the internal electrode 15 previously applied and the newly applied conductive paste a of the outer peripheral side are overcoated. . Next, as shown in FIG. 7, except for both ends of the porcelain element body 11, the dielectric slurry b which becomes the dielectric layer 14 is applied and dried. Further, as shown in FIG. 1, except for the right end of the porcelain body 11, a conductive paste a which becomes the internal electrodes 16 is applied and dried. Here, on the left end side of the porcelain body 11, the conductive paste a of the inner peripheral layer to be the internal electrode 16 previously applied and the newly applied conductive paste a of the outer peripheral side are overcoated. .

Thereafter, the conductive paste a and the dielectric slurry b are fired, and the dielectric layers 14, 14, ... And the internal electrodes 15, 15 are baked.
..., 16, 16, ... Are formed.

The adjustment of the application positions of the conductive paste a and the dielectric slurry b as described above is performed by the transfer rollers 20 and 21 and the porcelain element body 11.
This is done by moving the relative position to the direction of the central axis of the porcelain body 11. In this way, by partially shifting the coating positions of the upper and lower layers, the internal electrodes 15, 15 ...
6 and 16 can be insulated from each other or they can be connected.

As described above, the conductive paste a and the dielectric slurry b are not applied one by one for each porcelain element body 11, but a plurality of porcelain element bodies 11, 11, ... It is also possible to separate or cut the porcelain bodies 11, 1 ...

The cylindrical ceramic capacitor thus manufactured is often provided with a dielectric layer, a resin layer or the like as an insulating layer on the outermost peripheral surface. Depending on the case, as shown in FIG. 1, cap-shaped terminals 24, 24 may be fitted and used from both ends as external electrodes. Lead wires may be attached to the terminals 24, 24.

The internal electrode 1 provided on the outer peripheral side of the porcelain body 11
In addition to 5, 15, ..., 16, 16, ..., Internal electrodes can be provided on the inner peripheral side of the allotrope 11.

〔The invention's effect〕

As described above, according to the method for manufacturing a cylindrical ceramic capacitor of the present invention, it is not always necessary to separately form the external electrode in addition to the internal electrode, and when forming the external electrode, a process such as polishing is performed. Without doing so, a reliable connection with the internal electrode is made. As a result, it is possible to manufacture a cylindrical ceramic capacitor having a high yield with a small number of steps, and the productivity can be improved.

[Brief description of drawings]

FIG. 1 is a vertical sectional side view showing a cylindrical ceramic capacitor manufactured according to an embodiment of the present invention, FIGS. 2 to 7 are vertical sectional side views of the capacitor in a semi-finished state, and FIG. FIG. 9 is a schematic perspective view of an essential part showing an example of an apparatus for manufacturing a cylindrical ceramic capacitor for carrying out the invention, and FIG. 9 is a vertical sectional side view showing a conventional example of a cylindrical ceramic capacitor. 11 ... Porcelain body, 14 ... Dielectric layer 15, 16 ... Internal electrodes, a ... Conductive paste b ... Dielectric slurry

Claims (1)

[Claims] 1. A conductive paste (a) is applied to the outer peripheral side of the cylindrical porcelain body (11) except for the first end portion side of the cylindrical porcelain body (11), dried, and then porcelain body. The dielectric slurry (b) is applied to the outer peripheral side of the same porcelain element body (11) except both end sides of the body (11), dried, and then porcelain element body (1).
1) The conductive paste (a) is applied to the outer peripheral side of the same porcelain body (11) except for the second end side, dried and then the same except for both end sides of the porcelain body (11). The step of applying the dielectric slurry (b) to the outer peripheral side of the porcelain element body (11) and drying the conductive paste (a) and the dielectric slurry (b).
A method of manufacturing a cylindrical ceramic capacitor, comprising: