JPH0794360A - Manufacture of laminated ceramic capacitor - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide a method for manufacturing a monolithic ceramic capacitor in which bleeding of an internal electrode paste is less likely to occur in a printing process and a short-circuit defect rate can be improved. When the internal electrode layer is formed, the internal electrode pattern A is inclined by an angle θ with respect to the traveling direction S of the blade 4 of the printing squeegee.
Of the inner electrode 2 simultaneously passes through different parts of the internal electrode 2 for printing.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ceramic capacitor, and more particularly to a method of manufacturing a laminated ceramic capacitor.

[0002]

2. Description of the Related Art Monolithic ceramic capacitors have been used in a wide range because of their excellent characteristics such as small size and large capacity, semi-permanent life, and low impedance at high frequency. Since high-density mounting is required on the substrate, the market needs for chip components that support surface mounting are becoming more active. The conventional method for manufacturing a laminated ceramic capacitor is to produce a green sheet by forming a slurry with a dielectric ceramic powder and a binder such as an organic resin dispersed and mixed in an organic solvent to a certain thickness by the doctor blade method or the like. Is made of Au,
An internal electrode paste composed of a low resistance metal powder such as Ag, Pd, Cu, and Ni, a binder such as an organic resin, and an organic solvent,
An internal electrode is formed by printing on the green sheet by a screen printing method. The green sheet is punched together with the green sheet so that printed internal electrodes are alternately opposed to each other, laminated in a mold, and pressure-bonded by a hot press or the like to obtain a laminate. This laminated body is cut into individual capacitor elements,
Binder removal and firing are performed to obtain a monolithic ceramic capacitor element. External electrode terminals are formed on both end surfaces of each of the facing internal electrodes of the laminated ceramic capacitor element where the electrode lead-out portions are exposed to complete the laminated ceramic capacitor.

Here, in order to reduce the size and increase the capacity of the monolithic ceramic capacitor, a material having a large dielectric constant, which is a constant peculiar to the dielectric material forming the dielectric ceramic, is used, or the total area of the laminated electrodes is increased. There are three methods, one is to reduce the thickness of the dielectric layer sandwiched between the electrodes and the other is to be laminated. Here, it is very difficult and difficult to use a material having a large dielectric constant in terms of material development. Therefore, we are trying to increase the total electrode area by increasing the number of laminated layers due to thinning of the dielectric layer and thinning, when using the green sheet by the doctor blade method, when static electricity or handling, Since the green sheet has no strength, there is a limit to thinning it.

Therefore, after the dielectric paste is printed by a screen printing method and dried to form a dielectric layer,
Similarly, the internal electrode paste is manufactured by a printing lamination method of forming a laminated body by repeating the work of printing a plurality of patterns on the above-mentioned dielectric layer, drying and forming the internal electrode layer. There is.

When a plurality of rectangular unit electrode patterns are printed as internal electrode layers on the surface of the dielectric layer, the unit electrode patterns are printed by arranging them at a uniform pitch in the major axis direction and the minor axis direction. The internal electrode A pattern in which the squeegee direction is parallel to the long axis direction of the unit electrode pattern and the internal electrode B pattern in which the unit electrode pattern is displaced by a half pitch in the squeegee direction with respect to the A pattern are arranged on the dielectric layer. When printed by sandwiching it between the internal electrode A pattern and the internal electrode B pattern forming the effective portion of the capacitor, and the internal electrode lead-out portion for forming the external electrode terminal in a later step. When the number of layers of the internal electrodes is different and the number of layers is large, as shown in FIG. 3B, when the screen printing is performed, the blade of the squeegee is pressed into the printing surface. Due to the effect, a step is generated, when the internal electrode paste is printed, bleeding of the internal electrode cannot be performed, a clean internal electrode pattern cannot be formed, and folds occur at the lead-out portion of the internal electrode even in the stacking direction. In some cases, it could cause a short circuit.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problem of the occurrence of a step due to the pressing effect of a squeegee blade of screen printing, and to easily form a thin internal electrode layer and to prevent short circuit. It is an object of the present invention to provide a method for manufacturing a small-sized, large-capacity monolithic ceramic capacitor with a low occurrence rate.

[0007]

When printing an internal electrode layer on a dielectric layer, a blade of a print squeegee contacts and contacts a screen having a print pattern. According to the present invention, the thickness of the laminated body of the printed laminated portion of the internal electrode forming the effective portion of the capacitor is larger than that of the printed laminated portion of the internal electrode forming the lead-out portion to the external electrode terminal.
An angle is formed between the squeegee direction and the long axis direction of the unit electrode pattern so that the blade of the printing squeegee can simultaneously print over the effective portion over two or more places. As a result, only the overlapping portion of the electrodes sandwiching the ceramic layer of the internal electrode A pattern and the internal electrode B pattern forming the effective portion of the capacitor,
At the same time, the tip of the blade of the squeegee is prevented from passing through only the non-overlapping portions of the internal electrode A pattern and the internal electrode B pattern which will later form the external electrode terminals.

That is, at least at two or more locations,
Since the blade of the squeegee simultaneously straddles the printed laminated portion of the internal electrode (the portion that overlaps with the dielectric layer of the internal electrode layer) that constitutes the effective portion of the capacitor, the blade of the squeegee is not pushed in more than its thickness, The squeegee pushing effect is alleviated.

[0009]

In the overlapping portion of the internal electrode A pattern and the internal electrode B pattern forming the effective portion of the capacitor and the respective internal electrode lead portions forming the external electrode terminals later, in the thickness direction of the A pattern and the B pattern. Since there is no overlapping portion of the internal electrodes, there is a thickness difference corresponding to the thickness of the internal electrode, and when the non-overlapping portions of the A pattern and the B pattern are pressed against the printing surface by the squeegee of screen printing, a pressing effect is produced. Therefore, in order to mitigate this effect,
When printing a plurality of internal electrode patterns to be printed on the dielectric layer, the blade of the printing squeegee that passes through forms two or more printed laminated portions of the internal electrodes that make up the effective portion of the capacitor with a thick laminated body. Try to print again at the same time. In this way, the occurrence of a step due to the squeegee pushing effect is suppressed, so that it is possible to manufacture a monolithic ceramic capacitor with less bleeding during printing of internal electrodes and less short-circuiting due to folding.

[0010]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows internal electrode patterns A and B according to the present invention. FIG. 3 shows internal electrode patterns A and B according to the conventional method. FIG. 2 schematically shows a cross section of a monolithic ceramic capacitor constructed according to the present invention, and FIG. 4 schematically shows a cross section of a monolithic ceramic capacitor constructed by a conventional method.

In this embodiment, as the dielectric ceramic powder constituting the dielectric ceramic layer, a lead zirconate titanate (PZT) -based material having a dielectric constant of about 14000 is used, and polyvinyl butyral is used as the organic solvent binder. Ethyl cellosolve was added as an organic solvent in a weight ratio of 4%, and the mixture was dispersed and mixed with a homomixer to prepare a dielectric ceramic layer paste. Internal electrode layer paste is Ag80%, P
d20% mixed powder was used as an organic resin binder, ethyl cellulose, and an organic solvent, α-terpineol,
The one kneaded with a roll mill was used.

Using the dielectric ceramic layer paste and the internal electrode layer paste described above, the dielectric ceramic layer paste is repeatedly printed and dried to a thickness of 200 μm on a platen which has been subjected to a peeling treatment, to form a protective layer. . The internal electrode layer paste is printed and dried thereon by using the internal electrode pattern A shown in FIG. 1 (a) so that the printed thickness becomes about 3 μm, and the dielectric ceramic layer paste is printed at a printed thickness of 20 μm.
After being dried by printing so as to have a thickness of m, the internal electrode pattern B described above is used to obtain a printing thickness of about 3 μm as shown in FIG. Was repeated 51 times. Then, the dielectric ceramic layer paste was repeatedly printed and dried so as to have a thickness of 200 μm to form a protective layer, thereby producing a laminate.
After the laminate is cut into individual capacitor elements, about 400
After removing the binder at ℃, firing at 950 ℃, after chamfering, as shown in FIG. 2, the external electrode terminal 3 was applied to produce a chip type multilayer ceramic capacitor.

As can be seen by comparing FIGS. 2 and 4,
The folds of the internal electrodes near the internal electrode extraction portion are smaller than those of the conventional method. Even in the actual printing work, the bleeding of the internal electrode paste did not occur. Table 1 shows a comparison between the short circuit occurrence rate of the multilayer ceramic capacitor according to the present invention and the short circuit occurrence rate of the conventional method.

[0015]

[Table 1]

From Table 1, it can be seen that the short-circuit occurrence rate of the monolithic ceramic capacitor is improved.

[0017]

As described above, according to the present invention,
In the printing process, it is possible to provide a method for manufacturing a monolithic ceramic capacitor in which bleeding of the internal electrode paste is unlikely to occur and the short circuit defect rate can be improved.

[Brief description of drawings]

FIG. 1 is an explanatory view showing a printing state of internal electrodes according to the present invention. FIG. 1A is a schematic plan view. FIG. 1B is a schematic sectional view.

FIG. 2 is a schematic sectional view of a monolithic ceramic capacitor constructed according to the present invention.

FIG. 3 is an explanatory view showing a printing state of internal electrodes by a conventional method. FIG. 3A is a schematic plan view. FIG. 3B is a schematic sectional view.

FIG. 4 is a schematic cross-sectional view of a laminated ceramic capacitor formed by a conventional method.

[Explanation of symbols]

1 Ceramic 2 Internal Electrode 3 External Electrode 4 Squeegee Blade A Internal Electrode Pattern A B Internal Electrode Pattern B S Arrow that indicates the method of advancing the squeegee L Line that indicates the position of the blade tip of the squeegee θ (the advancing direction of the squeegee blade and Angle with pattern)

Claims (1)

[Claims] 1. A method of manufacturing a laminated ceramic capacitor, wherein an internal electrode paste and a dielectric paste are alternately laminated by screen printing and drying to perform lamination, and opposing internal electrode layers are connected to respective external electrode terminals. ,
The rectangular unit electrode patterns of the same shape are two-dimensionally aligned at equal intervals in each of the major axis direction and the minor axis direction, and the major axis direction of the unit electrode patterns is oriented with respect to the traveling direction of the squeegee. A method of manufacturing a monolithic ceramic capacitor, which comprises tilting and printing.