JPH0590067A - Manufacture of laminated ceramic capacitor - Google Patents

Abstract

PURPOSE:To easily manufacture a small size and a large capacitance laminated ceramic capacitor by laminating ceramics by coating an internal electrode forming paste, thereafter integrating such laminated ceramics through the pressure bonding thereof and then baking the laminated body to form an external electrode. CONSTITUTION:A green sheet having the surface coated with paste to form an internal electrode 2 is positioned at a specified position, the predetermined number of sheets are laminated with pressure and such laminated green sheets are cut with a cutter to form capacitor laminated bodies 1, 1. Thereafter, the capacitor laminated bodies 1, 1 are stacked and bonded with pressure to obtain a stacked body 3. Next, the obtained stacked body 3 is baked. Thereafter, the end face of backed body is coated with the pasts to form external electrode and the stacked body is baked to form an external electrode 4. Thereby, a laminated ceramic capacitor 5 is manufactured. Accordingly, a large capacitance laminated ceramic capacitor ensuring high reliability can be manufactured stably.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a novel method for manufacturing a laminated ceramic capacitor having a large capacity.

[0002]

2. Description of the Related Art A laminated ceramic capacitor is widely used especially as a chip type small electronic component. Such a laminated ceramic capacitor is usually formed with an internal electrode on the surface of a green sheet made of a predetermined dielectric composition. After applying a paste for coating, laminating a plurality of green sheets and press-bonding them, the laminated body is fired in the air to be integrated, and then the external electrode forming paste is applied to the end face and baked. Has been obtained by. For mass production, prepare a large-area green sheet, print the internal electrode forming paste at multiple positions on the surface and stack it, and then divide it with a cutter etc. to stack individual capacitors. The method of creating the body has been adopted.

On the other hand, the laminated ceramic capacitor is required to have a large capacity as a single component. The most common method for increasing the capacitance of a capacitor is to increase the number of laminated dielectric sheets. In addition, a method has also been proposed in which a plurality of laminated ceramic capacitors 13 each having an internal electrode 11 and an external electrode 12 formed thereon are overlapped as shown in FIG. 4, and the external electrodes 11 are bonded to each other with solder 14 or the like.

[0004]

However, in the method of increasing the number of laminated layers, the thickness of the laminated body itself becomes large, the laminated layer is apt to be displaced, the delamination is liable to occur, and moreover, the cutting is performed at the time of cutting with a cutter during mass production. There is a problem with the quality of the capacitor, such as the surface being broken and it becomes difficult to cut vertically with a cutter. Also,
When increasing the number of laminated sheets, it is possible to reduce the thickness of one green sheet, but there is a limit in terms of formability.

Further, in the method of superposing the once-formed laminated ceramic capacitors, a gap a is formed during the superposition and the capacitors are fixed only by the external electrodes, so that the strength is low and the reliability is poor. In addition, there is a problem that the thickness of the entire chip becomes large, which is unsuitable for downsizing.

[0006]

The inventors of the present invention have made repeated studies on the above-mentioned problems, and as a result, after applying and laminating internal electrode forming paste, the laminated body is superposed and pressure-bonded. It has been found that a small-sized and large-capacity laminated ceramic capacitor can be easily obtained by forming an external electrode by firing after being integrated.

The method of the present invention, particularly the method for mass production, will be described in detail below. First, a large-area dielectric green sheet is prepared based on the conventional method so that a plurality of capacitors can be obtained. The green sheet can be obtained by molding a mixed powder of a dielectric material such as BaTiO ₃ which is prepared to have a composition for forming a dielectric material into a sheet having a thickness of 15 to 30 μm by a known molding means such as a doctor blade method.

Next, a paste for forming internal electrodes, for example, a palladium paste or a silver-palladium alloy paste is printed on a predetermined position on the surface of the green sheet by a screen printing method or the like. Then, the green sheets to which the paste has been applied are aligned, and a predetermined number of green sheets are laminated and pressure-bonded. Then, the large-area laminate is cut by a cutter such as a guillotine blade to obtain capacitor laminates 1 and 1 as shown in FIG. In the figure, 2 is an internal electrode.

Thereafter, as shown in FIG. 2, the capacitor laminated bodies 1 and 1 are superposed and pressure-bonded to obtain a superposed body 3. At the time of this stacking, it is possible to perform the bonding without firing between the laminates 1 and 1 and to bond them by firing, but to prevent misalignment etc. when stacking the laminates, it is temporarily fixed with an adhesive such as resin. It is desirable to keep.

Next, the superposed body 3 obtained as described above.
Bake. The firing is performed at an optimum firing temperature depending on the composition of the dielectric material and under the condition that the internal electrodes can be fired at the same time. Further, at this time, if a weight is placed on the stack and baked, the adhesion between the stacked bodies 1 and 1 is improved. According to this firing, since the laminated bodies 1 and 1 are made of the same material, both react and adhere to each other to be integrated.

Thereafter, as shown in FIG. 3, an external electrode forming paste is applied to the end surface of the fired product and baked at a predetermined temperature to form the external electrode 4, whereby the laminated ceramic capacitor 5 can be prepared. it can.

[0012]

According to the method of the present invention, when manufacturing a large-capacity laminated ceramic capacitor, it is necessary to increase the number of laminated dielectric sheets. For example, when 100 layers are required to be laminated, Generally, the stacking accuracy is increased to 100
Although the layers were laminated, according to the method of the present invention, it is not necessary to form a laminated body of 50 layers and a laminated body of 100 layers, so that the lamination accuracy does not decrease.

Further, since the superposing step is carried out before firing, there is no gap between the superposed laminates, and since the two are bonded by the reaction during firing, the strength is high and the reliability is excellent.

[0014]

EXAMPLE A slurry was prepared using a Pb (Fe, Nb) O ₃ material as a dielectric material, and a 20 μm thick green sheet was prepared by the doctor blade method. Next, Ag / Pd internal electrode paste was printed on the surface of this green sheet, and 65 sheets were laminated and then thermocompression bonded at 60 ° C. Then, it cut | disconnected to the 5750 type | mold with a cutter, and produced the capacitor laminated body of thickness 1.4mm.

Next, two of these laminated bodies were aligned so that the exposed end faces of the respective internal electrodes were in the same plane to obtain a superposed body, which was placed on a floor plate to remove the binder at 240 ° C. After that, put the floorboard on top of the stack for 950
It was fired for 2 hours in the atmosphere of ° C. Observation of the stacked body after firing revealed that the stacked bodies were firmly attached to each other and were completely integrated.

After that, the end face of the superposed body is barrel-polished and A
The external electrode paste of g was applied and baked at 700 ° C. to obtain a laminated ceramic capacitor having a thickness of 3.0 mm and a capacity of 100 μF.

On the other hand, in order to obtain a capacitor having the same capacity, 130 green sheets were laminated and cut with a cutter, and a lamination deviation occurred. Also,
When the end face after firing was observed, the occurrence of delamination was confirmed.

[0018]

As described above in detail, according to the method for manufacturing a laminated ceramic capacitor of the present invention, when manufacturing a large capacity laminated ceramic capacitor, it is necessary to cut a laminated body having a large number of laminated dielectric sheets. Since it does not exist, there is no adverse effect such as collapse of the end faces, and the stacking accuracy can be easily managed. Moreover, since the strength of the superposed body is excellent, a highly reliable large-capacity laminated ceramic capacitor can be stably manufactured.

[Brief description of drawings]

FIG. 1 is a partially cutaway perspective view of a laminated body used in a method for manufacturing a laminated ceramic capacitor of the present invention.

FIG. 2 is a perspective view of a superposed body in the method for manufacturing a laminated ceramic capacitor of the present invention.

FIG. 3 is a perspective view of a laminated ceramic capacitor of the present invention.

FIG. 4 is a diagram for explaining a conventional large-capacity multilayer ceramic capacitor.

[Explanation of symbols]

 1 laminated body 2 internal electrode 3 superposed body 4 outer electrode 5 laminated ceramic capacitor

Claims (1)

[Claims] 1. A step of stacking a plurality of dielectric green sheets coated with an internal electrode forming paste to form a stack, a step of stacking a plurality of the stacks and pressure bonding, and baking the stack. And a step of forming an external electrode on the end face of the fired product, a method of manufacturing a laminated ceramic capacitor.