JPH0445964B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a method for manufacturing a multilayer ceramic capacitor, and particularly to a method for forming internal electrodes on a green sheet.

[Background technology]

Generally, this type of multilayer ceramic capacitor is manufactured, for example, as follows. That is, first, a green sheet (protective sheet) with a thickness of 100 to 200 μm
is stored in the formwork. Next, a plurality of green sheets (ceramic layers) having a thickness of 30 to 60 μm and having internal electrodes in a predetermined pattern on their surfaces are sequentially placed in a mold. Subsequently, a green sheet (protective sheet) with a thickness of 100 to 200 μm is stored. In this state, the green sheet is pressed by a pressing member to integrate the green sheet and the internal electrodes. Next, this laminate is sequentially cut vertically and horizontally using a cutter to form chips. Thereafter, a multilayer ceramic capacitor is obtained by firing the chip and forming external electrodes on both ends.

By the way, internal electrodes with a thickness of about 5 to 10 μm are formed on the surface of the green sheet constituting the ceramic layer by screen printing using a conductive paste containing palladium and silver. When the green sheets are laminated for pressure integration, a slight gap tends to be formed between the green sheets in the areas where the internal electrodes are not formed.

Therefore, when stacked green sheets are pressed with a pressing body, undesired distortion or deformation occurs inside the stack, which tends to cause warping, cracking, etc. during firing. This causes problems in characteristics such as a decrease in capacitance and loss of moisture resistance.

This tendency is particularly noticeable when the number of stacked green sheets is large, or when the thickness of the green sheets becomes thinner due to miniaturization and higher capacity of multilayer ceramic capacitors.

Therefore, it has been proposed to use a dielectric ceramic spacer sheet that has a gap in the portion corresponding to the internal electrode and has a thickness that is approximately equal to the thickness of the internal electrode (Japanese Patent Application Laid-Open No. 133553/1982). .

However, the thickness of the internal electrode is generally 5~
The thickness of the green sheet is approximately 30 to 50 μm, and the thickness of the dielectric ceramic spacer sheet is approximately 5 μm, which is approximately equal to that of the internal electrodes.
Achieving a thickness of ~10 μm is extremely difficult and is not only difficult to achieve, but also requires a green sheet with a uniform thickness and internal electrodes formed on it.
This method requires a dielectric ceramic spacer sheet and has the problem of increasing the number of parts.

[Disclosure of the invention]

Therefore, an object of the present invention is to eliminate gaps between green sheets in a stacked state before pressurization,
It is an object of the present invention to provide a method for manufacturing a multilayer ceramic capacitor that can reduce defects in characteristics caused by pressurizing operations and firing operations.

The feature of the present invention is that before the green sheets having internal electrodes formed in a predetermined pattern are laminated as appropriate and integrated under pressure, a pressing body having a pattern for the internal electrodes is used on the surface of the green sheets. The purpose of the present invention is to form a recessed portion of a certain depth, and to form an internal electrode in this recessed portion so as to be substantially flush with the green sheet.

According to this invention, the internal electrodes are formed in the recesses of a certain depth formed in the green sheets so that they are almost flush with the green sheets, so that even if a plurality of green sheets are stacked, they do not overlap each other. No gap is formed between them. For this reason, even if a large number of stacked green sheets or a thin stack of green sheets are pressed and fired in a stacked state, warping and cracking are less likely to occur, and deterioration of characteristics caused by this can be reduced.

[Best mode for carrying out the invention]

Next, an embodiment of the present invention will be described with reference to FIGS. 1 to 5.

First, as shown in Figure 1, ceramic powder,
The thickness of the mud containing binder and solvent is 30~
A green sheet 1 of 60 μm is formed. and,
After drying, by pressing using a pressing body having an internal electrode pattern on its surface at a pressure that is a fraction of the pressure used to press a normal laminated green sheet, A recessed portion 2 is formed. Next, as shown in FIG. 2, an internal electrode 3 is formed in the recess 2 so that its surface is substantially flush with the surface of the green sheet 1. Next, the third
As shown in the figure, a green sheet 1 is placed on a green sheet (protective sheet) 4 with a thickness of 100 to 200 μm.
Stack multiple sheets. Furthermore, a green sheet (protective sheet) 5 having a thickness of 100 to 200 μm is laminated on the green sheet 1. In this state, the green sheet is pressed by a pressing body. Through this operation, the green sheet and internal electrodes are integrated under pressure.
Then, by cutting this laminate along the dashed-dotted line, it is made into chips as shown in FIG. 4. Next, after firing this chip, external electrodes 6, 6 are formed on the exposed end faces of the internal electrodes 3, thereby obtaining a multilayer ceramic capacitor.

According to this embodiment, the internal electrodes 3 are formed in the recesses 2 previously formed in the green sheets 1 so as to be substantially flush with the surface of the green sheets 1, so that there is no space between the layers when the green sheets 1 are stacked. No gaps are formed at all. For this reason, even if the entire surface of the green sheets is laminated with a normal pressing force and then the group of green sheets is pressed, no undesired distortion remains inside the laminate, and warping and cracks due to firing can be reduced. .

In particular, when the thickness of the green sheet 1 is 20 μm and the thickness of the internal electrode 3 is 8 μm, warpage occurs compared to the conventional method.
Characteristic deterioration caused by cracks was halved. Moreover, in the present invention, since the internal electrodes are formed in the recesses formed by pressing the green sheet with the pressing body, warping and cracking caused by reducing the thickness of the green sheet, as well as a decrease in manufacturing yield, etc., are all eliminated. Not only is this possible, but it also has the advantage of being much easier to manufacture than a dielectric ceramic spacer sheet in which the portions corresponding to the internal electrodes are voids.

In the present invention, the thicknesses and number of layers of the green sheets and internal electrodes can be changed as appropriate. In addition to one internal electrode formed on the green sheet,
It is also possible to form a plurality of them at the same time.

[Brief explanation of the drawing]

The figures are explanatory diagrams of the method of the present invention, in which Fig. 1 is a side sectional view of a green sheet, Fig. 2 is a side sectional view showing a state in which internal electrodes are formed, and Fig. 3 is a side sectional view showing a stacked state of green sheets. 4 is a side sectional view of the chip state, and FIG. 5 is a side sectional view of the completed state. In the figure, 1 is a green sheet, 2 is a recessed part, and 3 is an internal electrode.

Claims (1)

[Claims] 1. Prior to suitably laminating green sheets on which internal electrodes are formed in a predetermined pattern and integrating them under pressure, a pressing body having a pattern corresponding to the internal electrodes is placed on the surface of the green sheets. 1. A method of manufacturing a multilayer ceramic capacitor, comprising: forming a recessed portion of a certain depth using a green sheet, and forming an internal electrode in the recessed portion so as to be substantially flush with a green sheet. 2. A patent claim characterized in that when a pressing body having a pattern corresponding to the internal electrode is used, the pressing body is pressed with a pressure that is one-tenth to one-tenth of the pressure used to press a normal laminated green sheet. range 1
A method for manufacturing a multilayer ceramic capacitor as described in .