JP2946844B2 - Manufacturing method of multilayer ceramic capacitor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[Industrial applications]

[0002] The present invention relates to a method for manufacturing a multilayer ceramic capacitor widely used for electric appliances such as a video tape recorder and a liquid crystal television.

[0003]

2. Description of the Related Art In recent years, with miniaturization and higher frequency of electronic devices, further miniaturization has been desired, and from such a viewpoint, demand for multilayer ceramic capacitors has been increasing.

[0004] The structure of a conventional multilayer ceramic capacitor will be described below. FIG. 3 is a perspective view showing a cross section of a part of the multilayer ceramic capacitor. In FIG. 3, 11 is a ceramic dielectric layer, 12 is an internal electrode, 13
Is an external electrode. The internal electrodes 12 are each connected to external electrodes 13.

Hereinafter, a method of manufacturing the conventional multilayer ceramic capacitor will be described with reference to the drawings. FIG. 4 is a view showing the structure of the ceramic laminate during the manufacturing.

First, a green sheet is prepared by a doctor blade method using a slurry comprising a dielectric powder such as barium titanate, an organic binder, a plasticizer and an organic solvent.

Next, internal electrodes are formed on the sheet by a screen printing method or the like using an electrode paste containing a noble metal such as palladium or platinum as a main component.

Next, the green sheets on which the internal electrodes are formed are arranged so that the internal electrode layers are alternately opposed to each other with the ceramic dielectric layer interposed therebetween, and are sequentially laminated. 14 is formed.

Next, the ceramic laminate 14 is bonded onto a metal plate 16 provided with an adhesive film 15 and held in an airtight bag 17 to improve the adhesion between the layers of the ceramic laminate 14. Then, hydrostatic pressurization is performed using a liquid such as water as a pressure medium to perform compression molding.

Next, after taking out the formed ceramic laminate from the bag 17, it is cut into chips of a desired size and fired at 1200 to 1400 ° C. Silver and silver were added to both ends of the sintered body thus obtained, and to internal electrodes appearing at both ends so that these internal electrodes were electrically connected.
External electrodes were formed by coating and baking silver-palladium or the like to manufacture a multilayer ceramic capacitor.

[0011]

However, the hydrostatic pressurization in the above-described manufacturing process is performed after the ceramic laminate produced in the preceding step is held in an airtight bag and sealed after vacuum sealing. The pressure was applied while leaving bubbles generated between the dielectric layers. Therefore, particularly when the amount of binder in the slurry is large, bubbles remaining between the dielectric layers cannot be removed to the outside, and there is a problem that cracks occur in the sintered body after firing.

In view of the above problems, the present invention can perform hydrostatic pressurization without leaving air bubbles between dielectric layers during hydrostatic pressurization in the manufacturing process of a multilayer ceramic capacitor. An object of the present invention is to provide a method for manufacturing a multilayer ceramic capacitor having excellent interlayer adhesion.

[0013]

In order to solve the above-mentioned problems, a method of manufacturing a multilayer ceramic capacitor according to the present invention is directed to a method of manufacturing a multilayer ceramic capacitor, in which green sheets on which internal electrodes are formed alternately face internal electrode layers with a ceramic dielectric layer interposed therebetween. In order to obtain a ceramic laminate by repeating lamination up to a desired number of laminations, a step of providing cutting grooves in the lamination direction of the laminate along a chip shape of a desired size, and Holding the laminate in an airtight bag, vacuum-sealing, applying hydrostatic pressure and compression molding, and, after compression molding, dividing the molded ceramic laminate into chips and firing. And a process.

According to another method of the present invention, at least one hole is formed in a part of a chip having a desired size, instead of the step of providing the cutting groove in the step. Providing a hole in the laminating direction of the ceramic laminate.

[0015]

As described above, before the hydrostatic pressing of the ceramic laminate fixed to the adhesive sheet, a cutting groove is provided in the laminating direction along a chip shape of a desired size, or a chip shape of a desired size is formed. By providing holes in the laminating direction of the ceramic laminate so as to have at least one hole in each of the parts, the part became an escape for air bubbles during hydrostatic pressurization and remained in the laminated chip. The bubbles move, and the occurrence of cracks can be suppressed.

[0016]

【Example】

(Embodiment 1) Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 shows the structure of a ceramic laminate during manufacture according to the first embodiment of the present invention. FIG.
Wherein 1 is a ceramic laminate obtained by repeatedly laminating green sheets on which internal electrodes are formed so that the internal electrode layers alternately face each other with the ceramic dielectric layer interposed therebetween and repeating the lamination to a desired number of laminations. Is a cutting groove, 3 is an adhesive film, 4 is a metal plate, and 5 is an airtight bag.

Hereinafter, a first embodiment of a method for manufacturing a multilayer ceramic capacitor according to the present invention will be described with reference to FIG. Here, the detailed description of the manufacturing process of the ceramic laminate similar to the conventional technology is omitted.

First, a high dielectric material containing barium titanate as a main component is used, butyral resin is used as a binder,
Either butyl carbitol or butyl carbitol acetate is blended as an organic solvent using either a ketone resin or a phenol resin, and the amount of binder is changed.
A ceramic laminate 1 consisting of a layer, a dielectric thickness of 8.0 μm per layer, an electrode thickness of 2.5 μm, a total thickness of 1.2 mm, and a total thickness of 1.2 mm was prepared and placed on a metal plate 4 provided with an adhesive film 3. Glue.

Next, using a metal blade having a blade thickness of 0.5 mm, a cutting groove 2 is formed in the laminating direction of the ceramic laminate 1 by using a metal blade having a blade thickness of 0.5 mm so that the ceramic laminate 1 has a chip shape of 4 mm × 2 mm square. Is provided. At this time, the ceramic laminate 1 is completely cut so that a part of the adhesive film 3 is cut.

Next, the entire ceramic laminate with a metal plate into which the cut grooves 2 are introduced is put into an airtight bag 5, sealed under reduced pressure, and subjected to a hydrostatic pressure of 100 kg / cm ² using water as a pressure medium.
And compression molding. At this time, the hydrostatic pressure is 250
When the pressure is more than kg / cm ² , the cutting groove 2 is closed and the chips may adhere to each other.
cm ² is appropriate. The hydrostatic pressure is appropriately determined depending on the number of layers, the amount of the binder, and the like.

Next, the formed ceramic laminate 1 is separated from the metal plate 4 and the layer of the adhesive film 3 and divided into chips according to the cut grooves 2 in the previous step. After removal at 400 ° C. for 4 hours in the middle for removal, baking is performed at 1300 ° C. for 2 hours. After firing, the results of examining the number of cracks generated in 1000 of the obtained sintered bodies are shown in (Table 1). Further, (Table 1) shows that 1000 sintered bodies produced by the conventional method produced in exactly the same manner as the present invention except for the cut grooves, and sintered bodies obtained by Example 2 of the present invention described later. The occurrence of cracks for 1000 pieces was determined by using a binder amount of 5 to 25.
% Is shown in comparison.

[0023]

[Table 1]

As is clear from the above (Table 1), before the hydrostatic pressure is applied as in this manufacturing method, by forming a cutting groove in the ceramic laminate in advance, the air bubbles remaining in the sheet are removed. In addition, even if the amount of the binder is large, a dense sintered body can be obtained, and a multilayer ceramic capacitor in which cracks hardly occur can be provided.

Embodiment 2 Hereinafter, another embodiment of the present invention will be described with reference to the drawings.

FIG. 2 shows the structure of a ceramic laminate during manufacture according to a second embodiment of the present invention. FIG.
In the figure, the same parts as those shown in FIG. 1 are denoted by the same reference numerals, and the description of the same steps in the manufacturing method will be omitted.

In the manufacturing method of the second embodiment, a chip-shaped 4 mm × 2 mm square
In the step of forming holes in the laminating direction of the ceramic laminate 1 so as to have holes 6 at the corners, instead of the firing step, after compression molding, the formed ceramic laminate is formed into a chip shape of 4 mm × 2 mm square. Then, using a metal blade having a blade thickness of 0.5 mm, a step of dividing into chips by a press-cutting method and firing it.

In the second embodiment, the ceramic laminated body 1 is provided with holes 6 at four corners of a chip shape of 4 mm × 2 mm square in the laminating direction of the ceramic laminated body.
What is necessary is just to have it in at least one location of the chip shape of 2 mm square.

As is clear from Table 1, by providing holes in the lamination direction of the ceramic laminate, bubbles remaining in the sheet are also removed, as is clear from (Table 1). Even if the amount of the binder is large, a dense sintered body can be obtained, and a multilayer ceramic capacitor in which cracks hardly occur can be provided.

[0030]

As described above, the present invention is obtained by repeatedly laminating green sheets on which internal electrodes are formed up to a desired number of laminations such that the internal electrode layers alternately face each other with the ceramic dielectric layer interposed therebetween. In the hydrostatic pressing step of the ceramic laminate, in the previous step, the ceramic laminate is provided with a cutting groove in each laminating direction along a chip shape of a desired size, or a part of a chip shape of a desired size. At least one
By having the step of providing two holes, bubbles remaining between the dielectric layers are removed, thereby providing a method of manufacturing a multilayer ceramic capacitor having excellent adhesion between the dielectric layers and preventing cracks. It is possible to realize an excellent effect of productivity.

[Brief description of the drawings]

FIG. 1 is a diagram showing a structure of a ceramic laminate during manufacturing according to a first embodiment of the present invention.

FIG. 2 is a diagram showing a structure of a ceramic laminate during manufacture according to a second embodiment of the present invention.

FIG. 3 is a perspective view showing a cross section of a part of the multilayer ceramic capacitor.

FIG. 4 is a diagram showing a structure of a multilayer ceramic laminate in a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Ceramic laminated body 2 Cutting groove 3 Adhesive film 4 Metal plate 5 Bag 6 Hole

Claims (2)

(57) [Claims] A step of laminating green sheets on which internal electrodes are formed so that the internal electrode layers are alternately opposed to each other with the ceramic dielectric layer interposed therebetween, and repeating the lamination to a desired number of layers to obtain a ceramic laminate. Providing a cutting groove in the laminating direction of the ceramic laminate along a chip shape of a desired size, holding the laminated ceramic laminate in an airtight bag, vacuum-sealing, and isostatic pressing. A method for manufacturing a multilayer ceramic capacitor, comprising: a step of compression-molding; and a step of, after compression-molding, dividing the formed ceramic laminate into chips and firing. 2. A step of obtaining a ceramic laminate by sequentially laminating green sheets on which internal electrodes are formed so that the internal electrode layers alternately face each other with the ceramic dielectric layer interposed therebetween, and repeating the lamination to a desired number of laminations. Providing holes in the stacking direction of the ceramic laminate so as to have at least one hole in each part of a chip shape having a desired size;
A step of holding the multilayer ceramic laminate in an airtight bag, vacuum-sealing, compressing by hydrostatic pressing, and after compression molding, dividing the molded ceramic laminate into chips and firing. And manufacturing the multilayer ceramic capacitor.