JPH07211576A - Manufacture of laminated ceramic capacitor - Google Patents

Abstract

PURPOSE:To provide a manufacturing method of a laminated ceramic capacitor which does not contain an internal-structure defect such as delamination or the like. CONSTITUTION:A laminated body is pressurized and compression-bonded in a high-humidity atmosphere at a relative humidity of 70% or higher. By this process, water molecules in large quantities are adsorbed to a dielectric layer, the plasticity of the dielectric layer is increased, the difference in level due to the thickness of an internal electrode is absorbed, and the compression rate of the laminated body is increased. As a result, it is possible to obtain a laminated ceramic capacitor which does not contain an internal-structure defect.

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 monolithic ceramic capacitor.

[0002]

2. Description of the Related Art In recent years, the demand for monolithic ceramic capacitors has increased more and more with the miniaturization and higher frequency of electronic equipment.

FIG. 2 shows a manufacturing process of a conventional general laminated ceramic capacitor. 3A is a vertical sectional view of the monolithic ceramic capacitor, and FIG. 3B is a horizontal sectional view thereof. Hereinafter, a general manufacturing method will be described with reference to the drawings. First, a dielectric green sheet 1 is formed by molding a ceramic raw material into a sheet with a doctor blade or the like, and a paste containing a metal to be the internal electrode 2, for example, palladium is screen-printed on the dielectric green sheet 1 in a predetermined pattern. Next, the dielectric green sheets 1 on which the conductor layers serving as the internal electrodes 2 are formed are arranged so that the dielectric layers serving as the internal electrodes 2 are alternately opposed to each other with the dielectric green sheet 1 interposed therebetween, and the layers are sequentially arranged. Lamination is performed, and the lamination is repeated until the desired number of layers is laminated. The laminated body thus obtained is pressure-bonded at room temperature and normal humidity and then cut into chips of a desired size. Then, the green chip is fired at a high temperature to obtain a sintered body. Next, a metal paste to be the external electrode 3 is applied to a predetermined portion of the end surface of this sintered body, and baked to form the external electrode 3
To form a monolithic ceramic capacitor.

[0004]

However, in the above-mentioned conventional structure, when the ceramic dielectric layers are laminated, an adhesion failure occurs because the thickness difference of the internal electrodes cannot be completely absorbed, and the element after firing has a problem. However, there is a problem that structural defects such as delamination occur.

Therefore, an object of the present invention is to provide a method for manufacturing a monolithic ceramic capacitor which does not cause structural defects such as delamination.

[0006]

In order to achieve this object, a method for manufacturing a monolithic ceramic capacitor according to the present invention comprises:
At least, the ambient humidity environment during the pressure-bonding step of the laminate is maintained in a high humidity atmosphere having a relative humidity of 70% or more.

[0007]

According to this structure, it is possible to suppress the adhesion failure between the dielectric layers during lamination and prevent structural defects such as delamination.

That is, according to the present invention, a large amount of water molecules are adsorbed to the ceramic dielectric layer by maintaining the ambient humidity environment at the time of pressure bonding under high humidity of 70% or more in relative humidity. Therefore, the phenomenon that the plasticity of the ceramic dielectric is increased, the internal electrode thickness step difference is absorbed, and the compression rate at the time of pressure bonding is increased is utilized.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be specifically described below with reference to FIG.

First, a ceramic raw material was mixed and granulated, and a dielectric green sheet 1 was used to form a lower support layer that did not contribute to the capacity on a pallet for lamination. Next, a commercially available palladium paste was used on the lower support layer to form the internal electrode 2 by screen printing, and after drying, the dielectric green sheet 1 was laminated and pressure-bonded. After that, the formation of the internal electrodes 2 and the lamination of the dielectric green sheets 1 were repeated while the lamination pallet was displaced by a predetermined size each time in order to obtain the capacitance in the same manner. After that, when the number of effective layers reached 30 layers, a supporting layer having the same thickness as the lower supporting layer was formed of the dielectric green sheet 1 on the uppermost layer to prepare a laminate. Next, after leaving this laminated body in an atmosphere of normal relative humidity of 50% for 1 hour, the pressure of 49MPa was maintained while maintaining the humidity atmosphere.
It was crimped with a. Further, the other laminates produced in the same manner were left under an atmosphere of relative humidity of 60%, 70%, 80%, 90% for 1 hour, and then pressure-bonded under a pressure of 49 MPa while maintaining the humidity atmosphere. The laminated pressure-bonded body thus obtained was cut into chips each having a desired size to produce a green chip. Next, these green chips were fired in air at a temperature of 1350 ° C. for 2 hours. The external electrode 3 is formed on this sintered body to obtain a monolithic ceramic capacitor. Therefore, the appearance and the inside of the element of each of the above-mentioned sintered bodies were observed to examine the presence or absence of structural defects such as delamination. The above results
The yield rate (%) for 1000 samples is shown in (Table 1).

[0011]

[Table 1]

As is clear from Table 1, the relative humidity 7
It can be seen that the one produced by pressure-bonding at 0% or more has an excellent effect on structural defect defects such as delamination.

FIG. 1 shows the relationship between the relative humidity atmosphere at the time of pressure bonding and the compression ratio of the dielectric green sheet. Looking at this figure, the higher the relative humidity during pressure bonding,
The pressure compression ratio of the dielectric green sheets is also increased, and the adhesive strength between the dielectric green sheets is improved.

In this embodiment, the humidity atmosphere is controlled after the laminated body is formed and pressure bonding is performed. However, even if the humidity atmosphere is controlled and pressure bonding is performed at the stage of stacking. , Its effect is the same. Further, even if the laminated body is left in an atmosphere having a relative humidity of 70% or more before the pressure-bonding, the effect remains the same.

[0015]

As described above, according to the present invention, the dielectric ceramic sheet can absorb the step difference in the thickness of the internal electrodes and improve the adhesive strength between the dielectric ceramic sheets. As a result, it is possible to provide a monolithic ceramic capacitor free from structural defects such as delamination.

[Brief description of drawings]

FIG. 1 is a graph showing the relationship between the relative humidity and the compressibility under pressure of a dielectric green sheet in one embodiment of the present invention during pressure bonding.

FIG. 2 is a manufacturing process diagram of a conventional monolithic ceramic capacitor.

FIG. 3A is a vertical sectional view of a monolithic ceramic capacitor, and FIG. 3B is a transverse sectional view of a monolithic ceramic capacitor.

[Explanation of symbols]

 1 Dielectric green sheet 2 Internal electrode 3 External electrode

Claims (2)

[Claims] 1. A laminated body is formed by laminating dielectric layers and internal electrode layers such that the internal electrode layers are alternately exposed at opposite ends of the dielectric layer to form a laminated body, and then the laminated body is formed. A method for manufacturing a monolithic ceramic capacitor, wherein a body is pressure-bonded in an atmosphere having a relative humidity of 70% or more, and then external electrodes are formed on both ends of the laminate where the internal electrodes are exposed. 2. A laminated body is formed by repeating lamination and pressure bonding so that the dielectric layer and the internal electrode layer are alternately exposed at opposite ends of the dielectric layer. A method for manufacturing a monolithic ceramic capacitor, wherein the relative humidity is 70% or more, and then external electrodes are formed on both ends of the multilayer body where the internal electrodes are exposed.