JPS6115315A - Method of producing laminated ceramic 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] (Technical Field) The present invention relates to a method for manufacturing a multilayer ceramic capacitor,
In particular, the present invention relates to an improvement in a method for forming a protective ceramic layer in a method of manufacturing a ceramic capacitor by forming internal electrodes on ceramic green sheets, laminating them into one piece, and cutting them.

(Prior art) Generally, in order to manufacture a multilayer ceramic ceramic, an organic solvent such as methyl cellosolve, a plasticizer such as dioctyl phthalate, and a binder such as polyvinyl butyral are added to ceramic powder such as barium titanate and kneaded. After turning into slurry, a long ceramic green sheet (hereinafter abbreviated as green sheet) is manufactured using a doctor blade method or the like. Next, the green sheet is cut to a desired size to obtain a green sheet film 1 (FIG. 1(a)). Next, internal electrodes 2 are formed at desired positions on this green 7-t film 1 by screen printing or the like, and internal electrode printed films 3 are formed.
(Figure 2(b)). Thereafter, the internal electrode printed films 3 are alternately rotated 180 degrees and stacked, and several green sheet films 1 are stacked on top and bottom of the film as protective layers, and the stacked body 4 is obtained by pressurizing and integrating them. Figure 1 (C)). Next, this laminate 4 is cut and separated into predetermined dimensions to obtain a raw multilayer ceramic capacitor chip 5 (FIGS. 1(d) and 1(e)).
. Next, the above-mentioned multilayer ceramic capacitor green chip 5 is completely fired at a temperature suitable for firing the ceramic powder, and the external electrode 7 is heated.
(Fig. 1)). However, such a conventional method for manufacturing an S-layer ceramic capacitor has the following drawbacks.

(a) It is difficult to determine the margin dimensions when cutting the laminated body into individual laminated ceramic capacitors.

(b) Due to the above-mentioned variation in cutting position, Fig. 1 fb
) It is necessary to provide the cutting margin e and mi with a predetermined width.

(c) As a means of checking the misalignment state of the internal electrodes of the laminated ceramic capacitor after cutting, the cutting margin width m shown in Figure 1 tb)
To check f, A-A shown in Fig. 1fd)
The margin width must be measured by cutting along the line ``* to expose the overlapping surface of the internal electrode 2 as shown in FIG. 1(e).

(ii) The length of the protective layer on the side surface of the multilayer ceramic capacitor (the part -l in FIG. 1(d)) must be at least 200 μm or more, taking into account variations in cutting accuracy.

(Objective of the Invention) An object of the present invention is to provide a method for manufacturing a laminated ceramic capacitor, which solves the conventional drawbacks.

(Structure of the Invention) According to the present invention, the process of mixing ceramic, glue powder with an organic solvent, plasticizer, and binder to form a slurry and sulfur, and after forming this slurry into a film, it is dried to form a green sheet. 4-electrode paste is printed on the desired position of this green sheet, the required number of green sheets for forming internal electrodes are stacked alternately according to the desired capacitance, and then only green sheets are placed above and below the green sheets. A process of laminating and pressurizing several layers using a protective film to form a capacitor assembly, and cutting this capacitor assembly to form a first plate-shaped capacitor assembly with internal electrodes exposed on both sides. and a step of laminating and pressurizing a protective layer consisting of only a green sheet on the exposed surface of the internal electrodes of the first plate-shaped capacitor assembly to form a second plate-shaped capacitor assembly with the internal electrodes covered. , cutting and separating the second plate-shaped capacitor assembly into individual capacitor pieces to expose the end faces of the internal electrodes; and after firing the individual capacitor pieces, external electrodes are attached to the end faces of the P3 part electrodes. A method for producing a laminated ceramic capacitor, which comprises a step of adhering and forming, is obtained.
Explain with reference to.

Titanium is made by adding an organic solvent such as methyl cellosolve, a plasticizer such as dioctyl phthalate, and a binder such as polyvinyl butyral to a barium-based ceramic powder, kneading it into slurry, and then forming it into a long green sheet using a doctor blade method etc. A green sheet IdlK is obtained which is completely manufactured and cut to the desired size (FIG. 2).

Next, internal electrodes 2 are formed in strips at desired positions on the green sheet pAl by screen printing or the like to obtain an internal electrode printed film (hereinafter abbreviated as printed film) 13 (see Fig. 2).
b)). Next, the required number of printed films 13 are stacked alternately by rotating 180° so as to obtain the desired capacitance, and several green sheet films 1 described above are stacked on top and bottom of the printed films 13 as protective layers. /li and pressurized and integrated using a hot press or the like to obtain a laminate 14 (FIG. 2(C)). Next, this laminate 14 is cut along lines B-B' and C-C' to obtain a first plate-shaped multilayer ceramic capacitor assembly (hereinafter referred to as a capacitor assembly) in which the internal electrodes 2 are exposed on both sides. Abbreviation) 9'
t-obtained (Fig. 2(d)). Next, several green sheet films 1 are laminated as a protective layer on both exposed sides of the internal electrodes 2 of the capacitor assembly 9 as shown in FIG. A second plate-shaped capacitor assembly 9A, f in which the internal electrodes 2 are not exposed is obtained by putting the capacitors into a single plate and integrating them under pressure (FIG. 2(e)).

Next, this capacitor assembly 9A= is cut into a predetermined size to obtain a raw multilayer ceramic capacitor chip 15 with internal electrodes 2 exposed at both ends (FIG. 2(f)).

Next, this laminated ceramic capacitor green chip 15 is fired, and external electrodes 7 are formed on both exposed ends of the internal electrodes 2 to produce a laminated ceramic capacitor 18 (FIG. 2, 1g)).

(Effect of the invention) The manufacturing method of the present invention has the following effects.

(1) Since the protective layer on the side surface of the multilayer ceramic capacitor is formed later, the side surface of the multilayer ceramic capacitor is
An internal electrode is provided. Therefore.

There is no need to provide the cutting margin l shown in FIG. 1(b) in the conventional manufacturing method.

(11) Since the internal electrodes are exposed in the side dimensions of the laminated ceramic and capacitor, the state of lamination misalignment can be easily confirmed.

fiii) Lamination misalignment in the width direction (Fig. 2 +, y
Since the capacitance accuracy does not occur, the capacitance accuracy can be improved.

qVl With the conventional manufacturing method, it was difficult to make the protective layer on the side of the multilayer ceramic capacitor as narrow as possible due to cutting precision, but with the one-piece manufacturing method, there was no problem with the withstand voltage of the ceramic powder and the rated voltage of the product. The range can be narrowed down.

Therefore, in a multilayer ceramic capacitor having the same shape, the internal electrode area can be increased compared to the conventional manufacturing method, and the capacitance range can be expanded.

[Brief explanation of the drawing]

FIG. 1(a) is a top view of the ceramic green sheet. Figure 1 jb) is a top view of the internal electrode printed film, Figure 1 fc)
is a top view of a laminate in which a printed film and a green sheet film are laminated and integrated under pressure, FIG. 1(d) is a perspective view of a raw multilayer ceramic capacitor chip, and FIG.
) is a cross-sectional view taken along the line A-A', Figure 1+f) is a perspective view of the laminated ceramic capacitor (after external electrode formation), and Figure 2
Figure (a) is a top view of a ceramic green sheet, Figure 2 fbl is a top view of an internal electrode printed film according to the manufacturing method of the present invention, and Figure 2 (C) is a top view of a ceramic green sheet in which the required number of printed films are alternately laminated and placed above and below. FIG. 3 is a top view of a laminate in which Green 7-Ii (as a protective layer) is laminated and integrated under pressure. Fig. 2 fdl is the laminated body of Fig. 2 (C) as 1=l-B'
FIG. 2(e) is a perspective view of the first plate-shaped multilayer ceramic capacitor assembly obtained by cutting along line C-C'.
FIG. 2(f) is a cross-sectional view of a mold in which green sheets are fully laminated on the internal electrode exposed surface of a plate-shaped multilayer ceramic capacitor assembly and integrated under pressure. FIG. 2(g) is a perspective view of a laminated ceramic capacitor after forming external electrodes. Reference numeral 1 in the figure: Green sheet film, 2: Internal electrode, 3゜13: - Internal electrode printed film, 4.14...
...Laminated body, 5.15...Multilayer ceramic capacitor raw chip. 6.6', 6"...Mold, 7...External electrode,
8゜18... Multilayer ceramic capacitor, 9...
(First) plate-shaped multilayer ceramic capacitor assembly, 1
, m, −j! ' , -m... Cutting margin width, W
Lamination misalignment of internal electrode. 4 ′ 1″t!A + “-IF: IN”, ′,,
. (θ) (b) (
C) (f) fshi /Q70A (e)

Claims (1)

[Claims] A method for manufacturing a multilayer ceramic capacitor, characterized by comprising the following steps. (B) A step of kneading an organic solvent, a plasticizer, and a binder to ceramic powder to form a slurry; (B) A step of forming a film of the slurry and then drying it to form a green sheet; (C) A step of forming the green sheet. A conductive paste is printed on the desired position of the sheet, and the required number of green sheets for forming internal electrodes are laminated alternately according to the desired capacitance, and then a number of protective films made of green sheets are added above and below as a protective layer. (d) cutting the capacitor assembly to form a first plate-shaped capacitor assembly with internal electrodes exposed on both sides; ) a step of laminating and pressurizing a protective layer of only a green sheet on the exposed surface of the internal electrode of the first plate-shaped capacitor assembly to form a second plate-shaped capacitor assembly covering the internal electrode; cutting and separating the second plate-shaped capacitor assembly into individual capacitor pieces to expose the end faces of internal electrodes; (g) after firing the individual capacitor pieces, forming external electrodes on the end faces of the internal electrodes; The process of adhering and forming.