JP2000150293A - Layered ceramic capacitor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a layered ceramic capacitor, in which electrode paste of base metal such as nickel, is used for internal electrodes. SOLUTION: In this layered ceramic capacitor including a sintered compact of a plurality of lamination layers of ceramic dielectric layers 2 and internal electrodes 1, made of nickel as its main component and alternately stacked therewith and also including external electrodes 3, provided so as to be electrically connected with the internal electrodes 1 at ends of the sintered laminated body, the internal electrodes 1 are formed with the use of paste for the internal electrodes 1, which is a mixture of 0.001-0.01 wt.% of amorphous carbon powder having a mean particle diameter of 0.001-0.01 μm added to a mean metal component.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multilayer ceramic capacitor using a base metal such as nickel for internal electrodes.

[0002]

2. Description of the Related Art Conventional multilayer ceramic capacitors are manufactured by using a known method of manufacturing a multilayer ceramic capacitor.
A stacked green chip obtained by alternately stacking a plurality of ceramic dielectric layers mainly composed of a high dielectric constant material such as iO ₃ and internal electrodes mainly composed of a base metal such as nickel in a reducing atmosphere in a reduction atmosphere of 1200 to 1200 After sintering at a temperature of 1500 ° C., an electrode paste is applied to the exposed end face of the laminated sintered body so as to be electrically connected to the internal electrode, and baked to provide an external electrode to provide a laminated ceramic. A method for completing a capacitor is generally used.

[0003]

In the prior art, in order to form an internal electrode using an electrode paste containing a base metal such as nickel as a main component, firing is carried out in a reducing atmosphere to prevent oxidation of nickel and the like. . For this reason, the ceramic dielectric layer material of the laminated green chip uses a reduction-resistant dielectric material that can be fired in a reducing atmosphere. However, when the firing temperature of the laminated green chip exceeds 1300 ° C., the firing of the nickel of the internal electrode is severe, and the internal electrode is cut inside the laminated sintered body, and the nickel or the like of the electrode material is deposited on the ceramic dielectric layer. There is a problem that the aluminum alloy diffuses and lowers insulation between the internal electrodes of the laminated sintered body.

The present invention has been made to solve the above problems, and to provide a multilayer ceramic capacitor having stable performance which can be fired even at a temperature of 1300 ° C. or more in the atmosphere even in the case of an electrode paste using a base metal such as nickel. It is intended for.

[0005]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention relates to a method for preparing a base metal electrode paste such as nickel by adding an amorphous carbon powder having an average particle size of 0.001 to 0.01 μm to a base metal component. By using the electrode paste added with 0.001 to 0.01 wt%, a multilayer ceramic capacitor having stable performance can be obtained.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The invention according to claim 1 of the present invention is directed to a laminated sintered body in which a ceramic dielectric layer and a plurality of internal electrodes mainly composed of a base metal such as nickel are alternately laminated;
In a multilayer ceramic capacitor having an external electrode formed at the end of the multilayer sintered body so as to be electrically connected to the internal electrode, the internal electrode has an average particle diameter of 0.001.
A multilayer ceramic capacitor in which internal electrodes are formed using an electrode paste obtained by adding 0.001 to 0.01 wt% of an amorphous carbon powder of 0.001 to 0.01 μm to a base metal component. When the base metal internal electrode such as nickel is fired and contracted by firing, the electrode is cut off, and the base metal such as nickel diffuses into the ceramic dielectric layer to lower the insulation resistance. The base metal such as nickel reacts with oxygen in the atmosphere or oxygen in the ceramic dielectric layer material to form an oxide during the sintering process. Diameter 0.001
By adding 0.01 μm of amorphous carbon powder, the amorphous carbon added in the sintering process of the laminated green chip reacts with oxygen in the atmosphere earlier than the base metal is oxidized, thereby oxidizing the base metal. Has the effect of suppressing

Hereinafter, an embodiment of the present invention will be described for a multilayer ceramic capacitor using a nickel internal electrode paste.

In advance, as a nickel internal electrode paste,
50% by weight of nickel metal powder having an average particle size of 0.1 μm;
To a component consisting of 50 wt% of an organic vehicle containing ethyl cellulose, terpineol, and mineral spirit as main components, an amorphous carbon powder in an amount shown in (Table 1) is further added to the nickel metal powder, and these are homogeneously kneaded. An electrode paste was prepared.

[0009]

[Table 1]

First, using a ceramic dielectric powder containing barium titanate as a main component, a dielectric green sheet having a thickness of 10 μm is manufactured according to a known method for manufacturing a multilayer ceramic capacitor. Next, ten dielectric green sheets are laminated to form upper and lower invalid layers. Next, the internal electrode paste is printed on the dielectric green sheet surface using a screen printing method.

Subsequently, 50 green sheets on which the internal electrodes are printed are alternately shifted by a predetermined amount alternately every other layer in the longitudinal direction of the printed internal electrodes, and finally, an invalid layer is overlaid on the upper and lower surfaces to perform pressure lamination. A laminate (not shown) is prepared.

Thereafter, the green laminate was cut into laminate green chips of a predetermined shape (product shape 3216 type), and fired at 1200 ° C. and 1300 ° C. in the air atmosphere.

As shown in FIG. 1, the obtained laminated sintered body has a state in which the internal electrodes 1 are alternately exposed to different end faces facing each other with the ceramic dielectric layer 2 interposed therebetween.

Next, an external electrode paste containing copper as a main component is applied so as to cover the end face of the laminated sintered body with the internal electrode 1 exposed, and then the paste is applied in a reducing atmosphere (in green gas).
The external electrodes 3 were formed by baking at a temperature of 00 ° C.

Next, in order to secure the solderability of the formed external electrode 3, a nickel film and a solder film are further formed on the surface of the external electrode 3 by using an electrolytic plating method. A multilayer ceramic capacitor having F characteristics described above was completed.

The capacitance, dielectric loss, and insulation resistance were measured for each of the 1,000 laminated ceramic capacitors having the internal electrodes formed using the respective internal electrode pastes shown in (Table 1). It is also shown in Table 1).

As shown in Table 1, an amorphous carbon powder having a particle diameter of 0.001 to 0.01 μm was added to a nickel metal powder in an amount of 0.001 to 0.01 wt%. A multilayer ceramic capacitor fired at 1300 ° C. using an internal electrode paste has a high insulation resistance of 10 ¹¹ or more and small variations in capacitance and dielectric loss. When the amount of the amorphous carbon added is less than 0.001 wt%, the insulation resistance is as low as 10 ⁹ or less, the variation in the dielectric loss is extremely large, and the amount of the amorphous carbon added is 0.01%.
It is understood that if the content exceeds wt%, the insulation resistance becomes extremely low, and it becomes difficult to measure characteristics.

Using the internal electrode paste of the present invention, 1200
It is considered that the low insulation resistance of the multilayer ceramic capacitor fired at ℃ is due to insufficient sintering of the multilayer body. It is considered that the effect of suppressing the oxidation of nickel is small, so that the internal electrode breakage or the nickel of the electrode component diffused into the ceramic dielectric layer, thereby lowering the insulation resistance and increasing the capacitance variation.

The amorphous carbon has a particle diameter of 0.001.
If it is smaller than μm, the dispersibility when kneading with the internal electrode paste is deteriorated, and if it is larger than 0.01 μm, the printability of the internal electrode paste is deteriorated, which is not preferable. Furthermore, when crystalline carbon is used instead of amorphous carbon, crystalline carbon has higher stability at high temperatures than amorphous carbon, and the effect of suppressing nickel oxidation is reduced, preventing deterioration of characteristics. It seems that you cannot do that.

As described above, by using the nickel internal electrode paste of the present invention in which the average particle size and the amount of amorphous carbon are specified, the obtained multilayer ceramic capacitor can be statically fired even at 1300 ° C. in the atmosphere. It is apparent that an excellent multilayer ceramic capacitor having stable capacitance, dielectric loss, and insulation resistance can be obtained.

[0021]

As mentioned above, according to the present invention, the nickel internal electrode paste of the multilayer ceramic capacitor is 0.001 to 0.001.
By adding 0.01 to 0.01 wt% of amorphous carbon powder of 0.01 μm to nickel metal powder, even in high temperature firing in the air, there is little variation in capacitance and dielectric loss and high insulation resistance. Thus, a stable multilayer ceramic capacitor can be provided.

[Brief description of the drawings]

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

[Explanation of symbols]

 1 internal electrode 2 ceramic dielectric layer 3 external electrode

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Koji Hirate 1006 Kazuma Kadoma, Kazuma, Osaka Prefecture F-term in Matsushita Electric Industrial Co., Ltd. 5E001 AB03 AC09 AE02 AE03 AF00 AH01 AH05 AH06 AH08 AH09 AJ01 5E082 AA01 AB03 BC35 BC38 BC38 EE04 EE23 EE28 EE35 FG06 FG26 FG27 FG54 GG10 GG11 GG26 GG28 HH43 JJ03 JJ12 JJ21 JJ23 LL02 MM22 MM24 PP03 PP09

Claims (1)

[Claims] 1. A laminated sintered body in which a plurality of ceramic dielectric layers and internal electrodes containing a base metal such as nickel as a main component are alternately laminated, and the internal electrode is electrically connected to an end of the laminated sintered body. In a multilayer ceramic capacitor provided with external electrodes formed so as to be connected to each other, an amorphous carbon powder having an average particle size of 0.001 to 0.01 μm is added to the internal electrodes in an amount of 0.001 to 0.01 wt% based on a base metal component. A multilayer ceramic capacitor with internal electrodes formed using the added electrode paste.