JP3538308B2 - Manufacturing method of multilayer ceramic electronic component - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a multilayer ceramic electronic component such as a multilayer ceramic capacitor.

[0002]

2. Description of the Related Art A multilayer ceramic capacitor, which is one of ceramic electronic components, is formed by laminating a ceramic sheet 11a on which internal electrodes are formed by a screen printing method using a metal paste 12a to form a laminate. After cutting into the shape of, firing was performed, and then an external electrode was formed.

[0003]

However, according to this method, as shown in FIG. 3, the thickness of the metal paste forming portion 14a and the thickness of the metal paste non-forming portion 15a of the ceramic sheet 11a are different from each other. Since the pressure is concentrated only on the forming portion 14a and the molding density of the metal paste non-forming portion 15a does not increase,
There was a problem that cracking and delamination tended to occur in this portion when firing.

Accordingly, the present invention provides a multilayer ceramic electronic component free from cracks and delaminations by applying sufficient pressure to a portion of a ceramic sheet where a metal paste is not formed at the time of pressing to strengthen the adhesion between the ceramic sheets. The purpose is to provide.

[0005]

Means for Solving the Problems] method of manufacturing a multilayer ceramic electronic component of the present invention to achieve this object, the weight
Polyethylene and ceramic having an average molecular weight of 400,000 or more
A first step of forming a metal film on a ceramic sheet containing a raw material by a thin film forming method, and then laminating a plurality of ceramic sheets on which the metal film is formed , applying pressure, and
And heat it while pressurizing to melt the polyethylene.
A second step of strengthening the adhesion between the ceramic sheets to obtain a laminated body; and a third step of firing the laminated body, wherein the ceramic sheet has a porosity of 30% or more. In addition to the fact that the conductor layer in the first step is formed by a thin film forming method, and the ceramic sheet in the second step has a high porosity, the conductor layer is formed at the time of pressure bonding. The above-mentioned object can be attained because the ceramic sheet in the portion where the conductive layer is formed has a high compression ratio, and a sufficient pressure is applied to the portion where the conductive layer is not formed.

[0006]

DETAILED DESCRIPTION OF THE INVENTION The invention according to claim 1 of the present invention relates to a polyethylene having a weight average molecular weight of 400,000 or more.
And a first step of forming a metal film on a ceramic sheet containing a ceramic raw material by a thin film forming method, and then laminating a plurality of ceramic sheets on which the metal film is formed.
And then heat while pressurizing to melt the polyethylene.
A second step of obtaining a laminated body by strengthening the adhesion between the ceramic sheets and a third step of firing the laminate, wherein the ceramic sheet has a porosity. A method for producing a multilayer ceramic electronic component characterized by being at least 30%, wherein the conductor layer is a thin film and the porosity of the ceramic sheet is high. Since a sufficient pressure is also applied to the non-formed portions, a multilayer ceramic electronic component free of cracks and delamination can be obtained. Also, this conductor layer,
Since a combustion component such as varnish is not contained unlike the conventional case, the conductor layer becomes denser than in the conventional case, and a multilayer ceramic electronic component having a low equivalent series resistance, that is, a small loss can be obtained.

According to a second aspect of the present invention, in the first step, the conductive layer is formed by using any one of a thin film forming method of vapor deposition, sputtering, plating, and electrostatic coating.
Wherein the conductor layer is a thin film and the porosity of the ceramic sheet is high, so that when performing the pressure bonding in the second step, the conductor layer is formed on a portion where the conductor layer is not formed. Since sufficient pressure is applied, a multilayer ceramic electronic component free from cracks and delamination can be obtained.

[0008]

An embodiment of the present invention will be described below with reference to the drawings, taking a multilayer ceramic capacitor as an example.

(Embodiment 1) FIG. 1 is a cross-sectional view showing one step of a monolithic ceramic capacitor according to the present embodiment, wherein 1a is a ceramic sheet, 2a is a metal serving as an internal electrode 2 formed on the ceramic sheet 1a. Reference numeral 4a denotes a metal film forming portion, 5a denotes a metal film non-forming portion, 6 denotes a metal upper plate, 7 denotes a metal lower plate, and 8 denotes a distance between the metal upper plate 6 and the metal lower plate 7. FIG. 2 is a partially cutaway perspective view of a general multilayer ceramic capacitor, wherein 1 is a ceramic dielectric layer, 2 is an internal electrode, and 3 is an external electrode.

First, a ceramic sheet 1a having a weight average molecular weight of 400,000 and a dielectric powder containing barium titanate as a main component and having a porosity of 70% is formed of nickel serving as an internal electrode 2 on a ceramic sheet 1a. The metal film 2a is formed by a thin film forming method. In this thin film forming method, a plurality of metal films 2a are formed in a desired shape by using, for example, sputtering. At this time, the thickness of the ceramic sheet 1a is 15 μm, and the thickness of the metal film 2a is 0.1 to 2.5 μm.
m. A plurality of ceramic sheets 1a are
The metal films 2a are stacked so as to alternately face each other with the ceramic sheet 1a interposed therebetween to obtain a temporary laminate. Thereafter, the temporary laminate is sandwiched between the upper metal plate 6 and the lower metal plate 7 and is pressed at room temperature by a uniaxial press at a gauge pressure of 5 to 100 WPa. Here, the surfaces of the metal upper plate 6 and the metal lower plate 7 that are in contact with the temporary laminate are polished, and the variation in the distance 8 between the surfaces of the metal upper plate 6 and the metal lower plate 7 is controlled to 40 μm or less. Then, after confirming that sufficient pressure has been applied to the temporary laminate, the temperature of the temporary laminate is increased until the maximum temperature of the temporary laminate becomes 150 ° C. to 200 ° C. to obtain a laminate. Here, the maximum temperature of the laminated body is 150 ° C.
The reason for setting the temperature to 200 ° C. is that the polyethylene melts at about 150 ° C., and the adhesion between the ceramic sheets becomes strong. The reason why the temperature is set to 200 ° C. or lower is that if the temperature is higher than 200 ° C., the polyethylene is decomposed and does not contribute to the adhesion between the ceramic sheets. Thereafter, the chip was cut into a chip shape having a length of 3.2 mm and a width of 1.6 mm, and the polyethylene was removed at 350 ° C. in the atmosphere (debuying). It is desirable that the temperature at the time of this de-buying be such that the polyethylene can be removed from the laminate and the oxidation of the nickel in the metal film 2a does not proceed too much. Thereafter, baking is performed at 1300 ° C. using a nitrogen gas and a hydrogen gas while maintaining an atmosphere in which the oxidation of the metal film 2a does not proceed excessively. By this firing, a sintered body is obtained in which the ceramic dielectric layer 1 mainly containing barium titanate and the internal electrode 2 mainly containing nickel are sintered simultaneously. Next, copper external electrodes 3 are baked on the exposed end surfaces of the internal electrodes 2 of the sintered body, and after plating, a finished product is obtained.

Table 1 shows the laminated ceramic capacitor of the present invention in which the internal electrode 2 is formed on the ceramic sheet 1a by sputtering, and the internal electrode 2 is formed on the ceramic sheet 1a.
Is formed by screen printing, and the film thickness and capacitance of the internal electrode 2 of the conventional multilayer ceramic capacitor in which the internal electrode 2 is formed by screen printing on the conventional ceramic sheet and the internal electrode 2 are formed on the conventional ceramic sheet. The results of an investigation on the relationship with the occurrence of structural defects are shown.

[0013]

[Table 1]

However, each of the multilayer ceramic capacitors has an effective number of layers of 100, and each of the 100 capacitors is examined for capacitance failure first. Then, for those having no capacitance failure, structural defects such as cracks and delamination are observed. The number is shown.

According to Table 1, when the thickness of the internal electrode 2 is less than 0.1 μm in the product of the present invention, when the laminated body is fired, nickel as the internal electrode 2 is sintered in a continuous form. Therefore, a predetermined capacitance could not be obtained. Further, when the thickness is 3.0 μm or more, since the adhesiveness between the ceramic sheets 1a is not sufficiently obtained, cracks 100 and delamination as shown in FIG. 4 were observed in the sintered body. Therefore, it is preferable that the thickness of the internal electrode 2 be 0.1 to 2.5 μm. Similarly, in the comparative example product in which the internal electrode 2 is formed by screen printing, when the film thickness of the internal electrode 2 is 1.5 μm or less,
When a predetermined capacitance could not be obtained and the thickness was 3.0 μm or more, a structural defect was observed. In addition, the conventional product in which the internal electrode 2 is formed by screen printing on a conventional ceramic sheet,
When the film thickness of the internal electrode 2 was 1.5 μm or less, a predetermined capacitance could not be obtained. When the film thickness was 2.0 μm or more, structural defects such as cracks and delamination were observed. Therefore, in the multilayer ceramic capacitor of the present invention, when the film thickness of the internal electrode 2 is in a wide range of 0.1 to 2.5 μm, structural defects such as cracks, which have occurred frequently in the past, and discontinuity of the internal electrode are caused. Capacitance failure can be suppressed, and the yield can be greatly improved. This further increases the number of effective layers,
When higher stacking is performed, there is a further effect.

The points of the present invention will be described below. (1) Although good results were obtained when the thickness of the internal electrode 2 was 0.1 to 2.5 μm, when the number of effective layers exceeds 100, the thickness of the internal electrode 2 is reduced to 1.0 μm or less. Thus, it is desirable to uniformly press the temporary laminate.

(2) Nickel is used as the material of the internal electrode 2, but a base metal such as copper or a noble metal such as palladium or silver-palladium may be used.

(3) Although the sputtering method is used for forming the thin film, any method of vapor deposition, plating, and electrostatic coating may be used. However, when the metal film 2a is formed by plating, it is preferable to use a neutral plating solution having a pH of around 7, in order to prevent the plating solution from affecting the ceramic sheet.

(4) In the first embodiment, only the multilayer ceramic capacitor has been described. However, a multilayer varistor, a multilayer thermistor, a multilayer filter, a ferrite component, a ceramic multilayer substrate, and the like manufactured by using the ceramic sheet 1a. Similar effects can be obtained in the production of ceramic electronic components.

[0020]

As described above, according to the present invention, it is possible to suppress the occurrence of structural defects of the sintered body due to uneven pressure during lamination, and to make the conductive layer denser than in the conventional case, and to reduce the equivalent series. A multilayer ceramic electronic component having a low resistance, that is, a small capacitance loss can be obtained. In particular, there is a remarkable effect on the improvement of the yield of the multilayer chip capacitor requiring high lamination.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a crimping step as one manufacturing step of a multilayer ceramic capacitor according to an embodiment of the present invention.

FIG. 2 is a partially cutaway perspective view of a general multilayer ceramic capacitor.

FIG. 3 is a cross-sectional view showing a crimping step as one manufacturing step of a conventional multilayer ceramic capacitor.

FIG. 4 is a perspective view of a sintered body having cracks.

[Explanation of symbols]

1 ceramic dielectric layer 1a Ceramic sheet 2 Internal electrode 2a Metal film 3 External electrodes

   ────────────────────────────────────────────────── ─── Continuation of front page    (72) Inventor Kurumitsu Hideki               1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric               Kiki Sangyo Co., Ltd. (72) Inventor Kazuhiro Komatsu               1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric               Kiki Sangyo Co., Ltd.                (56) References JP-A-8-124787 (JP, A)                 JP-A-5-190043 (JP, A)                 JP-A-3-273696 (JP, A)

Claims (2)

(57) [Claims] Claims: 1. A polyester having a weight average molecular weight of 400,000 or more.
A first step of forming a metal film on a ceramic sheet containing ethylene and a ceramic raw material by a thin film forming method, and then laminating a plurality of ceramic sheets on which the metal film has been formed, pressing, and then pressing Heat the poly
Melting ethylene to bond the ceramic sheets together
A second step of obtaining a laminated body in the strong, then a third step of firing the laminate, the ceramic Sea
A method for manufacturing a multilayer ceramic electronic component, wherein the porosity is 30% or more. 2. A method for forming a thin film, comprising: vapor deposition, sputtering,
The method for manufacturing a multilayer ceramic electronic component according to claim 1, wherein the method is one of plating and electrostatic coating.