JPH07302728A - Multilayered ceramic capacitor and its manufacture - Google Patents

Abstract

PURPOSE:To improve the thermal compression-bonding of a green sheet, and prevent the generation of delamination while the step-difference of an inner electrode is relieved, by printing ceramic slurry composed of the same dielectrics as the green sheet, so as to cover the inner electrode printed on the green sheet. CONSTITUTION:An inner electrode of a plurality of patterns is printed on a green sheet together with markers for alignment. Dielectric ceramic slurry which has been used for forming the green sheet is printed on the green sheet, so as to cover the inner electrode except the marker parts. Thereby a green sheet wherein the inner electrode is buried in the ceramic sheet is formed. The green sheet is punched, and laminated to form a laminate of a multilayered ceramic capacitor. Since the inner electrode is not exposed in the case of heat press molding, heat press compression-bonding is improved. Further the step- difference due to the thickness of the inner electrode can be decreased.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laminated ceramic capacitor, and a green sheet used for forming a laminated body of a laminated ceramic capacitor.

[0002]

2. Description of the Related Art Monolithic ceramic capacitors have been used in a wide range of fields due to their excellent characteristics such as small size and large capacity, semi-permanent life, high frequency and low impedance, etc. In order to deal with the above, chip formation is rapidly progressing.

A monolithic ceramic capacitor is composed of a ceramic slurry which is dispersed and kneaded by using a high dielectric ceramic powder as a material and an organic resin, and is formed with a certain thickness on a film which is peeled by a doctor blade method or the like. On the filmed green sheet, a low resistance metal powder such as silver and palladium and an organic resin are dispersed and kneaded in a solvent, and an internal electrode paste is obtained so that a plurality of capacitor elements can be obtained from one laminated body later. Then, multiple patterns are printed. Punching the green sheet thus obtained into a certain shape,
Repeated stacking, hot press molding the stack to cut into individual capacitor element shapes along the internal electrode pattern, remove the binder, and fire, then take out the internal electrodes stacked inside and remove the terminal electrodes. An external electrode is formed to obtain a capacitor element.

Here, the organic resin and the solvent used for the internal electrode paste printed on the green sheet are different from the organic resin and the solvent for producing the green sheet until the printed internal electrode paste is dried. It is common to use an organic resin and a solvent having different components so that the organic resin and the solvent used for the internal electrode paste do not attack the green sheet. Therefore, when the green sheet is punched out into a certain shape, and the lamination is repeated and hot press molding is performed, thermocompression bonding is performed between the back surface of the green sheet (the surface on which the internal electrodes are not printed) and the internal electrode portion. Since the organic resins are different from each other, the thermocompression bonding property is poor, resulting in defective compression bonding in the raw laminate before binder removal / sintering, resulting in delamination. Furthermore, when stacking the green sheets on which the internal electrodes are printed, a step due to the thickness of the internal electrodes occurs, and between the internal electrode portion and the ceramic margin portion that protects the peripheral internal electrodes, When the stress due to shrinkage during sintering is extremely large, microcracks and delamination may occur.

[0005]

The technical problem of the present invention is to prevent the occurrence of a crimping failure during the thermocompression bonding of a green sheet, and to reduce the step due to the thickness of the internal electrodes to prevent delamination. A method for manufacturing a green sheet, a green sheet manufactured by the method, and a method for manufacturing a laminated ceramic capacitor using the green sheet.

[0006]

According to the present invention, a plurality of patterns of internal electrodes are printed on a green sheet together with a positioning marker so that a plurality of ceramic capacitor elements can be obtained. The dielectric ceramic slurry used to make the green sheet is printed with a certain thickness so as to cover the internal electrode printed area except for the marker area, and a green sheet with the internal electrodes embedded in the ceramic sheet is made. A method for manufacturing a monolithic ceramic capacitor is characterized in that a laminated body of a monolithic ceramic capacitor is manufactured by punching out and stacking sheets.

Further, in order to obtain a plurality of ceramic capacitor elements, a green sheet on which a plurality of internal electrode patterns are printed together with a positioning marker is provided on a printed portion of the internal electrode excluding the positioning marker portion. , A ceramic slurry made of the same dielectric material as the green sheet is printed with a constant thickness,
This is a method for manufacturing a green sheet in which internal electrodes are embedded in this ceramic sheet.

Further, obtained by the above manufacturing method,
It is a green sheet for producing a laminated ceramic capacitor.

[0009]

[Function] After the internal electrodes are printed, a printing process using a slurry made of a dielectric ceramic of the same material as that of the green sheets is added to produce the green sheets, so that the internal electrodes are embedded in the green sheets, and thus hot press molding is performed. At this time, since the internal electrodes are not exposed, the front surface and the back surface of the green sheets using the same organic resin are overlapped with each other, and the hot press-bonding becomes good, and the crimping failure does not occur. Furthermore, since the printed portion of the internal electrodes is covered with ceramic, it is possible to reduce the step due to the thickness of the internal electrodes.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. In this embodiment, a high dielectric constant material having a lead-based composite perovskite structure and a dielectric constant of 14000 is used for the dielectric ceramic powder, and silver is 80% and palladium is 20% for the internal electrodes.
The mixed powder of was used.

The ceramic powder, the organic resin, and the solvent were dispersed and kneaded in a ratio shown in Table 1 using a high-speed homomixer, and a ceramic slurry was formed into a film by a doctor blade method to a dry thickness of 25 μm. The internal electrode paste prepared by kneading the mixed powder of silver and palladium, the organic resin and the solvent in the ratio shown in Table 2 with a three-roll mill was dried by screen printing to a thickness of 3.5 μm.
Printing was performed so that the capacitor element had a cross-sectional shape of 3 mm × 4 mm in m. Further, a ceramic slurry for a green sheet was printed on the portion excluding the alignment marker so that the thickness after drying became 5 μm to produce a green sheet according to the present invention.

[0012]

[Table 1]

[0013]

[Table 2]

On the other hand, for comparison, the above ceramic slurry was dried to a thickness of 30 μm by the doctor blade method.
A green sheet was formed by printing the above internal electrode paste by screen printing on the formed green sheet so as to have a dry thickness of 3.5 μm and a capacitor element shape of 3 mm × 4 mm. .

Seventy-two layers of the green sheets thus produced were laminated and thermocompression-bonded at 115 ° C. and 280 kg / cm ² by hot pressing, and cut into individual element shapes. After removing the binder at 450 ° C and firing at 950 ° C, shape the terminal electrodes so that the laminated internal electrodes can be taken out, and have a capacitance of 3.3 μF.
The multilayer ceramic capacitor of was produced.

The laminated ceramic capacitor thus obtained was subjected to a non-contact inspection with an ultrasonic flaw detector, then polished in the width direction, and the laminated cross section was observed to examine the result of the delamination occurrence rate. It shows in Table 3.

[0017]

[Table 3]

Table 3 shows that the delamination rate of the monolithic ceramic capacitor was improved.

[0019]

As described above, according to the present invention, when the hot press molding is performed, since the green sheets using the same organic resin are hot press-bonded, no crimping defect occurs. Further, it becomes possible to manufacture a laminated body capable of reducing the step due to the thickness of the internal electrodes, and as a result, it is possible to provide a laminated ceramic capacitor in which delamination is unlikely to occur and a method for manufacturing a green sheet used for the laminated ceramic capacitor. became.

[Brief description of drawings]

FIG. 1 is an explanatory view showing a schematic manufacturing process of a multilayer ceramic capacitor according to the present invention. FIG. 1A is a flowchart showing a manufacturing process. FIG. 1B is a diagram showing a film forming process. Figure 1
(C) is a figure which shows an internal electrode printing process. FIG. 1D is a diagram showing a slurry printing process. FIG.1 (e) is a figure which shows a hot press molding process. FIG.1 (f) is a figure which shows a laminated body.

FIG. 2 is an explanatory diagram showing a schematic manufacturing process of a conventional laminated ceramic capacitor. FIG. 2A is a flowchart showing the manufacturing process. FIG. 2B is a diagram showing a film forming process. Figure 2
(C) is a figure which shows an internal electrode printing process. FIG.2 (d) is a figure which shows a hot press molding process. FIG.2 (e) is a figure which shows a laminated body.

Claims (3)

[Claims] 1. A method for manufacturing a laminated ceramic capacitor, wherein a plurality of parallel internal electrodes facing each other in layers are provided inside a dielectric ceramic, and a terminal electrode is provided at the internal electrode lead-out portion. After printing the internal electrodes on each of the plurality of green sheets to be printed, a ceramic slurry made of the same dielectric material as the green sheets is printed to a predetermined thickness so as to cover the printed portions of the internal electrodes. A method for manufacturing a characteristic multilayer ceramic capacitor. 2. A green sheet having a plurality of internal electrode patterns printed thereon, so as to cover a printed portion of the internal electrodes, so as to obtain a plurality of ceramic capacitor elements.
A method for producing a green sheet, which comprises printing a ceramic slurry having the same dielectric material as that of the green sheet with a predetermined thickness. 3. A green sheet having a plurality of internal electrode patterns printed thereon, so as to cover a printed portion of the internal electrodes, so as to obtain a plurality of ceramic capacitor elements.
A green sheet, characterized in that a ceramic slurry made of the same dielectric material as the green sheet is printed with a predetermined thickness.