JPS59168623A - Method of producing ceramic laminated capacitor - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a ceramic multilayer capacitor, and more particularly to a method for manufacturing a small-sized, large-capacity capacitor.

Description of Prior Art When manufacturing a ceramic multilayer capacitor, a ceramic slurry is made into an N film using a doctor blade, etc., and after drying, a metal powder paste such as palladium or silver-palladium is printed as an internal electrode, and many sheets of these are printed. Stack and crimp to integrate. This is fired at 1,100° C. to 1,350° C. to make it porcelain, and external electrodes are applied thereto to obtain a ceramic multilayer capacitor chip.

A ceramic green sheet printed with internal electrodes at an intermediate stage of the manufacturing process as described above is shown in Figure 1. In Figure 1, 1 is a ceramic green sheet and 2 is an internal electrode. .

In the above manufacturing process, the aspects of manufacturing the ceramic green sheet will be described in detail as follows. Using a doctor blade, apply the dielectric powder and binder onto a mirrored stainless steel plate or plastic snack tape.
A slurry, which is a mixture of a dispersant and a solvent, was applied, dried, and peeled off to obtain a ceramic green sheet with a thickness of 35 to 60 μm. The capacitance per unit volume of a capacitor is determined by the dielectric constant of the ceramic dielectric, the total area of the internal electrodes, and the square of the thickness of each dielectric layer.
In order to obtain a small capacitor with a large capacity, it is necessary to reduce the thickness of the dielectric layer.

However, for the following reasons, the thickness of ceramic green sheets has conventionally been limited to about 35 μm. In other words, if the ceramic green sheet is made thinner than this limit, (1) micro defects in the ceramic green sheet, such as pinholes, will develop into fatal defects such as shorting between electrodes, and (2) the tensile strength of the ceramic green sheet will weaken. (3) It is difficult to handle the internal electrode paste, and it is not possible to automatically perform processes such as peeling off the ceramic green sheet, printing internal electrodes, and drying the ceramic green sheet in a continuous sheet state. The ceramic green sheet may be deformed due to solvent penetration, causing inconvenience in subsequent processes.

Purpose of the Invention Therefore, the purpose of the present invention is to improve the tensile strength when handling ceramic green sheets even when they are extremely thin, and to automate the printing of internal electrodes and the drying process of ceramic green sheets. An object of the present invention is to provide a method for manufacturing a ceramic multilayer capacitor that enables the following.

Another object of the present invention is to provide a method for manufacturing a ceramic multilayer capacitor that can minimize the development of minute defects in ceramic green sheets into fatal defects.

Still another object of the present invention is to provide a method for manufacturing a ceramic multilayer capacitor in which deformation of internal electrodes after printing is prevented.

Summary of the Invention In the present invention, a ceramic multilayer capacitor is obtained through the following steps. First, ceramic slurry
For example, a polyester film ("3" in FIG. 2), which has good adhesion to the binder inside, is prepared. Although it is preferable for this resin film to be as thin as possible, its thickness is determined in relation to tensile strength. For example, in the case of a polyester resin film, one having a thickness of about 1.5 to 14 μm is used. Ceramic slurry layers (FIG. 2..."1") are formed on both surfaces of such a resin film, resulting in a three-layer structure sheet 1-(FIG. 2..."4"). The layer of ceramic slurry can be formed by applying the doctor blade method to both sides of the resin film, but the pulling method, which involves passing the resin film through the ceramic slurry, simultaneously forms the layer of the resin film. It is efficient in that a layer of ceramic slurry can be formed on both sides. This three-layer grooved sheet 4 is dried as appropriate.

Next, an internal electrode ("2" in FIG. 2) is formed on one side of such a three-layer structure sheet without peeling off the ceramic slurry layer from the resin film. The internal electrodes are preferably automatically printed and the printed internal electrodes are dried. Thereafter, as in the conventional case, a plurality of these three-layer 1N sheets are stacked so that the internal electrodes are alternately led out from different ends, and are integrated by pressure if necessary. By firing this, the resin film located in the middle of each three-layer Frl sheet is burnt out. If the thickness of the resin film is below a certain level, the layer in which it existed will burn out at the same time as the resin film.
The upper and lower ceramics are integrally bonded and virtually no gap layer remains. An external electrode electrically connected to the internal electrode is formed on the end face of the multilayer sintered body obtained as described above to obtain a ceramic multilayer capacitor chip.

Effects of the Invention According to this invention, the mechanically weak ceramic green sheet can be handled as a three-layer structure sheet with a resin film interposed, so that the tensile strength can be increased. It is easy to handle, and it is easy to automate the printing of internal electrodes and the drying process of ceramic green sheets. Further, due to such advantages in handling, it is naturally possible to reduce the thickness of the ceramic dielectric layer, and it becomes possible to manufacture a small-sized, large-capacity ceramic multilayer capacitor. For example, the average tensile strength of conventional ceramic green sheets is 20 to 40
0/mm2, but with the three-layer sheet according to the present invention, it has become possible to increase it to 10,000 to 20,000(]/mm2.In addition, the formation of the ceramic green sheet requires the interposition of a resin film. , so to speak 2
Since the process is carried out in layers, the probability that the micro defects occurring in each two layers will line up in the thickness direction is extremely rare.
The fatal defect of pinhole formation can be reduced to zero.

Description of Examples sa T+ Os 89% by weight, ca zr o-1
10% of an acrylic water-soluble binder as an organic binder and 0.1% of a dispersant were added to a high permittivity dielectric composition powder consisting of 0% mass% and MQ Ti Oa 1.0% mass%, and Wet mixing was performed for 12 hours using pure water. The resulting slurry was defoamed in a vacuum container and then transferred to a stainless steel container. Next, as shown in Table 1 below, each thickness in the range of 1.5 to 20μ■ is set, and the width is 15cm.
am polyester film was passed through the slurry in the above-mentioned stainless steel container and pulled up vertically at a constant speed to form a uniform layer of slurry on both sides of the polyester film. This slurry was heat-dried to obtain a 3 RIt sheet (Figure 3) in which the ceramic green sheets (1) were adhered to both sides of the polyester film (3). The thicknesses of the ceramic green sheets in these three-layer structure sheets 1 to 1 are as shown in Table 1. These three-layer structure sheets (4) were punched into a rectangle of 7.0 x 10.0 cm using a mold, and palladium paste was printed on this using a screen printer to form internal electrodes (2) (Figure 3). After drying, stack 10 sheets of 3-layer structure sheets (4) printed with -C1 and 10 sheets each of 3-layer structure sheets 1 to 4a (not printed on top and bottom) so that the internal electrodes alternately face each other. (Figure 4).

Put this in a mold, 40.-80'C, 0.5~2
They were crimped and integrated under the conditions of ton/cm7. For example, cut out a single element of a capacitor from the integrated enclosure with a blade along the cutting line (5) in FIG.
After avoiding burning the binder at 0 to 500°C for 5 to 15 hours, it was fired at 1340°C for 2 hours to form porcelain. After firing, a silver paste was applied to the chip (6) as an external electrode (7) and baked at 800'C''c (Fig. 5).

The dimensions of this chip are thickness 0.2~0.5n+m, height 5.
．． QIRIII, horizontal 4. It was OLIlm.

The characteristics of each sample obtained in this way are
Shown in the table. In Table 1, the thickness of the polyester film of each sample (μl11), the total thickness of both sides of the ceramic green sheet (μm), the tensile strength per I Cm of the ceramic green sheet (k(+>), Number of through-hole defects (15
cm x 1 m), layer defects in the Wi layer after firing (
The number of occurrences (delamination) (number of occurrences per 100 samples), the thickness (μm) of one dielectric layer after firing, and the average capacitance are shown. 100 pieces of each sample were prepared, and the first
The numerical values in the table represent the average values.

As a comparative example, similar data were measured for several samples of ceramic multilayer capacitors manufactured using conventional manufacturing methods, and are shown in Table 2.

Table 1-U As is clear from the data shown in Table 1, the thinner the polyester film, the better. If the polyester film is thicker than 14 μm, layer defects (delamination) will occur in more than half of the sintered bodies, and the capacitance as designed may not be obtained. Furthermore, as is clear from the comparison between Table 1 and Table 2, the strength of the ceramic green sheet produced by the conventional method is more than an order of magnitude weaker than the strength of the ceramic green sheet produced by the present invention. It is unsuitable for the process, and thin sheets of 30 μm or less have a large number of minute through pinhole defects.
When made into a finished product, short-circuit defects occur frequently.

In the description of the above examples, a polyester film was used as the resin film. This polyester film has high tensile strength and is superior to other resin films in terms of heat resistance.

Therefore, for example, the ceramic slurry layer has excellent heat resistance during drying, and there is an advantage that the ceramic slurry layer can be made thin while maintaining dimensional stability.

Therefore, the dielectric layer interposed between the internal electrodes can be made thinner, and as a result, a larger capacity can be obtained. However, the resin film is not limited to such a polyester film, and may be a resin film made of a suitable material, such as a polyethylene film.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing a ceramic green sheet on which internal electrodes, which are one component of a laminate of a ceramic multilayer capacitor, are formed by a conventional method. FIG. 2 is a perspective view showing a ceramic green sheet on which internal electrodes, which are one component of a ceramic multilayer capacitor, are formed according to the present invention. 3 to 5 sequentially show the steps for obtaining a ceramic multilayer capacitor according to the present invention, and FIG. 3 is a cross-sectional view of one ceramic green sheet provided with internal electrodes;
Figure 4 is a cross-sectional view of a block made by stacking and integrating multiple layers of these, and Figure 5 is a cross-sectional view of a multilayer capacitor in which external electrodes are provided on a single chip cut and fired along cutting line 5 in Figure 4. be. In the figure, 1 is a ceramic green sheet or a layer of slurry, 2 is an internal electrode, 3 is a resin film or polyester film, 4 is a three-layered sheet, 6 is a capacitor chip, and 7 is an external electrode.

Claims (1)

[Claims] A resin film having good adhesion to a binder in a ceramic slurry is prepared, and a layer of ceramic slurry is formed on both sides of the resin film to form a 5WIJ Seizo sheet, and the three-layer structure sheet is 1~
An internal electrode is formed on one side of 3j! on which the internal electrode is formed. A plurality of sheets are laminated to form a laminate so that the internal electrodes are alternately led out to different ends of the iI manufactured sheet 1, and the resin film is burned at the same time as the laminate is fired to form a plurality of internal electrodes. A method for manufacturing a ceramic multilayer capacitor, comprising: forming a ceramic sintered body containing: an external electrode electrically connected to the internal electrode on the outer surface of the fired fI layer body;