JPH09260203A - Laminated capacitor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a laminated capacitor wherein the generation rate of structure defect is reduced even if it is miniaturized. SOLUTION: A laminated capacitor which is comprised of a rectangular solid-state element assembly 23 formed by laminating a dielectric layer 21 containing carbon of 1ppm or more and 5000ppm or less and an inside electrode 22 alternately and a pair of outside electrodes 24 connecting an inside electrode 22 in parallel alternately at both end parts of the element assembly 23. Thereby, strength of the element assembly 23 is increased, structural defect such as cracks is not generated even if the shape thereof is made compact, the generation rate of a defective article can be reduced and a yield can be improved. Furthermore, since the content of carbon is set at a specified value of 1ppm or more and 5000ppm or less, strength can be increased without damaging insulation property of a dielectric layer.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multilayer capacitor, and more particularly to a multilayer capacitor with reduced occurrence of structural defects.

[0002]

2. Description of the Related Art FIGS. 2 to 4 show a conventional multilayer capacitor. 2 is an exploded perspective view, FIG. 3 is a plan view, and FIG.
3 is a sectional view taken along line AA of FIG.

[0003] In the drawing, reference numeral 10 denotes a multilayer capacitor in which a dielectric body 13 formed by alternately laminating dielectric layers 11 and internal electrodes 12 and internal electrodes are alternately connected in parallel at both ends of the dielectric body 13. And a pair of external electrodes 14.

The internal electrode 12 is composed of an internal electrode piece 12a provided near the central region of the dielectric layer 11 and an internal electrode lead portion 12b provided along the external electrode 14 and connected to the external electrode 14. The internal electrode piece 12a is connected to the external electrode 14 via the internal electrode lead-out portion 12b.

[0005] The dielectric layer 11 is formed of a ceramic sintered body on a rectangular sheet, and the ceramic sintered body is formed of a dielectric ceramic material containing, for example, barium titanate as a main component. The internal electrode 12 is formed of a metal thin film obtained by sintering a metal paste. As the metal paste, for example, an electrode mainly containing a noble metal material such as Pd or Ag-Pd is used. The external electrode 14 is also formed of the same material as the internal electrode 12, and the surface is plated with solder to improve solder wettability.

[0006]

However, when the shape is made small, it often becomes a defective product even if some structural defects such as cracks occur.

In view of the above problems, it is an object of the present invention to provide a multilayer capacitor which has a reduced incidence of structural defects even though it is small.

[0008]

In order to achieve the above object, the present invention provides, in claim 1, an element body in which dielectric layers and internal electrode layers are alternately laminated, and both end portions of the element body. In a multilayer capacitor comprising a pair of external electrodes in which the internal electrodes formed in the internal electrode layers are alternately connected in parallel, the dielectric layer or the internal electrode layers containing a predetermined amount of carbon. We propose a multilayer capacitor.

According to the multilayer capacitor, since the dielectric layer or the internal electrode layer forming the element body contains a predetermined amount of carbon, the strength of the element body is increased.

According to a second aspect, in the multilayer capacitor according to the first aspect, the carbon content is 1 ppm.
A multilayer capacitor set to a predetermined value of not less than 5000 ppm is proposed.

According to the laminated capacitor, the amount of carbon contained in the dielectric layer or the internal electrode layer constituting the element body is 1 or less.
Since it is set to the predetermined value of not less than ppm and not more than 5000 ppm, it is possible to increase the strength without impairing the insulating property of the dielectric layer.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is an external perspective view showing a multilayer capacitor in one embodiment, and FIG. 5 is a side sectional view.
In the figure, reference numeral 20 denotes a multilayer capacitor, which includes an element body 23 in which dielectric layers 21 and internal electrodes 22 are alternately laminated, and a pair of internal electrodes 22 alternately connected in parallel at both ends of the element body 23. And the external electrode 24.

The dielectric layer 21 is made of a rectangular sheet-shaped ceramic sintered body, and the sintered body is made of a dielectric ceramic material formed by firing a green sheet containing barium titanate as a main component, for example. In addition, this green sheet has a predetermined amount of 1 ppm or more and 5000 ppm or less in weight ratio,
For example, 100 ppm of carbon (C) is added.

Each of the pair of internal electrodes 22 adjacent to each other through the dielectric layer 21 has a rectangular shape.
The long side of is substantially perpendicular to the external electrode 24. The width of each internal electrode 22 is formed to be equal.

Further, the internal electrode 22 connected to one external electrode 24a is positioned so as to be located in the outermost layer.
Is set.

The other external electrode 24b is made up of the element body 23.
Is formed longer than one external electrode 24a so as to cover a predetermined range on the upper and lower sides and both side surfaces.

On the other hand, the internal electrodes 22 are made of a metal thin film obtained by sintering a thin film of a conductive paste, and the conductive paste is mainly composed of palladium powder, for example. In addition, the external electrode 24 is also the internal electrode 22.
It is formed of the same material as the above, and the surface is plated with solder in order to improve solder wettability.

This multilayer capacitor was manufactured as follows. First, an organic binder was added to the dielectric raw material powder.
% By weight and 100 ppm of carbon were added, and further 50% by weight of water was added, and these were put in a ball mill and thoroughly mixed to prepare a slurry of a dielectric ceramic raw material.

Next, after putting this slurry in a vacuum defoamer to defoam it, put it in a reverse roll coater to form a thin film of this slurry on a polyester film,
This thin film is dried by heating to 100 ° C. on a polyester film, punched out, and 10 cm square, about 2 mm thick.
A green sheet of 0 μm was obtained.

On the other hand, 10 g of palladium powder having an average particle size of 1.5 μm and 0.9 g of ethyl cellulose dissolved in 9.1 g of butyl carbitol were placed in a stirrer.
By stirring for 10 hours, a conductive paste for an internal electrode was obtained.

After that, the above-mentioned internal electrode pattern
Using each of the screens having zero, a pattern of the internal electrode made of the conductive paste was printed on one surface of the green sheet, and dried.

Next, a plurality of green sheets were laminated with the printing surface facing upward, and further, unprinted green sheets were laminated on the upper and lower surfaces of this laminate. Then
This laminate was pressed at a temperature of about 50 ° C. by applying a pressure of about 40 tons in the thickness direction. Thereafter, the laminate was cut into a lattice to obtain about 50 laminated chips.

Next, this laminated chip is placed in a furnace capable of firing in an atmosphere, heated to 600 ° C. in the atmosphere to fire the organic binder, and then the atmosphere of the oven is set to the atmosphere in the atmosphere to heat the laminated chip. The temperature was maintained at 600 ° C. to 1150 ° C. (maximum temperature), which is the firing temperature, for 3 hours. After this, 1
The temperature was lowered to 600 ° C. at a rate of 00 ° C./hr and cooled to room temperature to obtain a sintered body chip.

Next, a conductive paste consisting of silver, glass frit and vehicle is applied to the side surface of the sintered body chip where the internal electrodes are exposed and dried, and this is dried in air at 800 ° C.
Baking at a temperature of 15 minutes to form a silver electrode layer, further depositing copper thereon by electroless plating, and providing a Pb-Sn solder layer thereon by electroplating to form a pair of external electrodes did. As a result, a multilayer capacitor was obtained.

According to the multilayer capacitor 20 having the above-described structure, since the dielectric layer 21 forming the element body 23 contains 1% by weight of carbon, the strength of the element body 23 is increased and the shape is reduced. Even in the case of the above, structural defects such as cracks do not occur, the occurrence rate of defective products can be reduced, and the yield can be improved.

Although the carbon content in the dielectric layer 21 is 100 ppm in this embodiment, the carbon content is not limited to this, and the carbon content is 1 ppm or more and 5000 ppm or more.
If it is set to a predetermined value of ppm or less, it is possible to increase the strength without impairing the insulating property of the dielectric layer 21,
More preferably, it is about 2 to 100 ppm. The carbon content can be obtained by appropriately adjusting the debinding process, firing temperature, firing atmosphere, binder amount, and the like.

[0027]

As described above, according to claim 1 of the present invention, since the dielectric layer or the internal electrode layer forming the element body contains a predetermined amount of carbon, the strength of the element body is increased. Therefore, even if the shape is made small, structural defects such as cracks do not occur, the incidence of defective products can be reduced, and the yield can be improved.

According to claim 2, in addition to the above effects, the carbon content is 1 ppm or more and 5000 ppm or more.
By setting the following predetermined value, the strength can be increased without impairing the insulating property of the dielectric layer.

[Brief description of drawings]

FIG. 1 is an external perspective view showing a multilayer capacitor according to an embodiment of the present invention.

FIG. 2 is an exploded perspective view showing a conventional multilayer capacitor.

FIG. 3 is a cross-sectional plan view showing a conventional multilayer capacitor.

FIG. 4 is a sectional view taken along line AA of FIG. 3;

FIG. 5 is a side sectional view showing a multilayer capacitor according to an embodiment of the present invention.

[Explanation of symbols]

20 ... Multilayer capacitor, 21 ... Dielectric layer, 22 ... Internal electrode, 23 ... Element body, 24 ... External electrode.

Claims (2)

[Claims] 1. An element body formed by alternately laminating dielectric layers and internal electrode layers, and internal electrodes formed on the internal electrode layer are alternately connected in parallel at both ends of the element body. A multilayer capacitor comprising a pair of external electrodes, wherein the dielectric layer or the internal electrode layer contains a predetermined amount of carbon. 2. The carbon content is 1 ppm or more and 5
The multilayer capacitor according to claim 1, wherein the multilayer capacitor is set to a predetermined value of 000 ppm or less.