JP2003157720A - Manufacturing method of conductive paste and laminated electronic component - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method of a conductive paste and a laminated electronic component in which occurrence of cracks on the element body of the laminated electronic component is prevented. SOLUTION: Powder of carbide is added to a conductive paste that has at least metallic powder, carbide powder, an organic binder, and an organic solvent. As the carbide, a carbide having a wetting angle of 0-90 deg. to the metallic powder in the conductive paste is desirable. As the carbide, TiC is suggested when the metallic powder is Ni, and WC is suggested when the metallic powder is Cu. It is desirable that the content of the carbide is 0.05-15 wt.%.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a conductive paste used to form an internal electrode or an external electrode of a laminated electronic component, and a method for manufacturing a laminated electronic component using this conductive paste.

[0002]

2. Description of the Related Art A monolithic ceramic capacitor, which is one of monolithic electronic components, is generally obtained by alternately laminating a plurality of layers of ceramic green sheets and conductor patterns and cutting each conductor pattern into chips. It is manufactured by adding a conductive paste for external electrodes to the end of the chip-shaped laminated body and firing it at a high temperature of about 1200 ° C., for example.

Here, the ceramic green sheet is formed by connecting ceramic raw material powder with an organic binder to form a sheet, and the ceramic green sheet is sintered to form a dielectric layer by sintering the ceramic raw material powder.

The conductor pattern is made of a conductive paste for internal electrodes. The conductive paste for the internal electrodes and the conductive paste for the external electrodes are both made of a composition containing a metal powder, an organic binder and an organic solvent, and the conductive paste for the internal electrodes burns the metal powder by firing. The conductive powder for the external electrode is formed into a single internal electrode, and the conductive paste for the external electrode is sintered to form an external electrode by sintering the metal powder.

[0005]

By the way, the ceramic green sheet and the conductive paste shrink during the sintering, but the firing shrinkage of the ceramic green sheet and the burning shrinkage of the conductive paste are quite different. Therefore, there is a problem that strain may occur between these electrodes and the dielectric layer during firing, resulting in cracks in the element body of the obtained laminated electronic component.

[0006] It is an object of the present invention to provide a conductive paste which prevents cracks in the element body of a laminated electronic component, and a method for producing a laminated electronic component.

[0007]

The conductive paste according to the present invention is characterized by containing at least a metal powder, a carbide powder, an organic binder and an organic solvent.

Further, in the method for manufacturing a laminated electronic component according to the present invention, the conductive paste for the internal electrode has at least a metal powder, an organic binder and an organic solvent, and further has a carbide powder. It is characterized by.

Here, as the metal powder, for example, P
Noble metal powder such as d, Pt, Ag, Au, Ni, Cu
Powders of base metals such as or alloys thereof can be used.

Examples of the organic binder include acrylic resin, phenol resin, alkyd resin, rosin ester, and various types of cellulose. However, the organic binder is not limited to these and may be any organic compound which is burned off by firing. However, it is possible to use other than these.

As the organic solvent, alcohol-based, hydrocarbon-based, ether-based and ester-based solvents can be used, but other organic solvents may be used.

The carbide preferably has a wetting angle of 0 to 90 degrees with respect to the metal powder in the conductive paste. When this carbide having a wetting angle of more than 90 degrees is used, it is necessary to add a large amount of carbide to the extent that the electrical characteristics of the electrode are affected. However, a carbide having a wetting angle of 0 to 90 degrees was used. This is because the desired laminated electronic component can be obtained in this case.

Here, the wetting angle of the carbide to the metal powder means that the metal powder is placed on the carbide plate to be measured and heated to a temperature higher than the melting temperature of the metal powder in the atmosphere for firing the laminated electronic component so that the metal is The contact angle formed when the liquid droplets are formed is the wetting angle.

Examples of such a carbide include TiC when the metal powder in the conductive paste is Ni and WC when the metal powder in the conductive paste is Cu. If the conditions are satisfied,
Carbides other than these, for example, Cr ₃ C ₂ , NbC, S
You may use iC etc.

Further, since the carbide functions to prevent the shrinkage of the electrode, it does not vaporize and disappears by firing, but a part or all of it changes to a solid oxide,
Those that expand in volume are preferred.

The content of the above-mentioned carbide is 0.05 to 1
5 wt% is preferable. Carbide content is 0.05 wt%
When it is less than the above range, the effect on the difference in shrinkage is reduced and cracks occur. If the content of carbides exceeds 15 wt%, the electrical characteristics such as the life of the capacitor will deteriorate. This is because, when the content of the carbide is in the range of 0.05 to 15 wt%, there is no such inconvenience and a desired laminated electronic component can be obtained.

In addition to the above-mentioned components, it is common to add additives to the conductive paste. As the additive, a compound such as BaCO ₃ or TiO ₂ , a ceramic powder having the same quality as the ceramic layer, an organic bentonite, or the like can be used.

The method of manufacturing a laminated electronic component is a step of forming a chip-shaped ceramic laminated body in which conductor patterns made of a conductive paste for internal electrodes and ceramic green sheets are laminated alternately, It goes without saying that it also includes a step of firing the ceramic laminate coated with the conductive paste.

In addition to the above steps, a step of applying a conductive paste for external electrodes to the end portions of the ceramic laminate is provided before the firing step, and the internal electrodes are used as the conductive paste for the external electrodes. Similar to the conductive paste for use in the above, carbide powder may be further included. The laminated electronic component includes a laminated ceramic capacitor, a laminated inductor, a laminated composite LC chip and other laminated electronic components.

[0020]

[Examples] First, barium titanate and other raw material powders are weighed, pulverized and mixed in a ball mill to prepare a ceramic raw material powder, and an organic binder and an organic solvent are added to the ceramic raw material powder, and the mixture is thoroughly mixed in a ball mill. Kneading and using the obtained ceramic slurry, a ceramic green sheet was formed by a doctor blade method.

Further, the ceramic material formed for the dielectric layer is pulverized to prepare a ceramic powder having a particle size of 0.2 μm, and this ceramic powder, Ni powder, TiC (carbide) powder, ethyl cellulose and butyl carbitol are mixed in 3 parts.
It was put into the present roll mill and sufficiently kneaded to prepare a conductive paste for external electrodes and a conductive paste for internal electrodes.

Next, a conductor pattern of a conductive paste for internal electrodes was printed by a screen printing method on a barium titanate-based ceramic green sheet formed for a dielectric layer. Then, after the conductor pattern is dried, 50 layers of this ceramic green sheet are laminated, pressed and pressed,
It was cut into dice to obtain a chip-shaped laminate. Then, a conductive paste for external electrodes was added to the end of this chip-shaped laminated body, and this was put into a firing furnace and fired at 1200 ° C. to obtain a laminated ceramic capacitor.

Next, the electrical characteristics of this monolithic ceramic capacitor were examined and the results are shown in Table 1. Further, this multilayer ceramic capacitor was cut along a plane that passed through the external electrode and was perpendicular to the internal electrode, the cut surface was mirror-polished, and observed with an optical microscope to examine the number of cracks. It was as shown in.

[0024]

[Table 1]

From the results shown in Table 1, it is understood that the occurrence of cracks is suppressed when the carbide is added to the conductive paste. Further, it is understood that when the wetting angle is 0 to 90 degrees, the generation of cracks can be suppressed with a small addition amount.

When the cross section of the external electrode of the monolithic ceramic capacitor was observed with an optical microscope, the presence of oxide particles was confirmed inside the external electrode in addition to the ceramic particles added as a co-material. It is considered that this is because the carbide added to the conductive paste was oxidized and formed.

[0027]

According to the present invention, when a powder of carbide is added to the conductive paste for the external electrode, the carbide is oxidized and volume-expanded to suppress the contraction of the external electrode, and the stress applied to the element body. Is alleviated, which has the effect of suppressing the occurrence of cracks near the external electrodes.

Further, according to the present invention, when the carbide powder is added to the conductive paste for the internal electrodes, the sintering of the ceramic particles near the internal electrodes is suppressed, and the particle size of the ceramic particles near the internal electrodes is suppressed. Are uniform, the internal stress is reduced, and the generation of cracks is suppressed.

Further, according to the present invention, when a carbide having a wetting angle of 0 to 90 degrees with respect to metal powder is used, there is an effect that generation of cracks can be suppressed with a small amount of the added carbide.

Further, according to the present invention, when a carbide which changes into a solid oxide by firing is used, there is an effect that the contraction of the electrode is further suppressed and the generation of cracks is further suppressed.

Continued front page    F-term (reference) 5E001 AB03 AE02 AH01 AH09 AJ01                       AJ02                 5G301 DA06 DA10 DA22 DD01

Claims (13)

[Claims] 1. A conductive paste comprising at least a metal powder, a carbide powder, an organic binder and an organic solvent. 2. The conductive paste according to claim 1, wherein a wetting angle of the carbide with respect to the metal is 0 ° to 90 °. 3. The conductive paste according to claim 1, wherein the carbide is a compound that changes into a solid oxide by firing. 4. The content of the carbide is 0.05 to 15 w.
It is t%, The electrically conductive paste in any one of Claims 1-3 characterized by the above-mentioned. 5. The metal is Ni and the carbide is T
It is iC, The electroconductive paste in any one of Claims 1-4 characterized by the above-mentioned. 6. The metal is Cu and the carbide is W
It is C, The electroconductive paste in any one of Claims 1-4. 7. A step of forming a chip-shaped ceramic laminate formed by alternately laminating conductor patterns made of a conductive paste for internal electrodes and ceramic green sheets, and a step of firing the ceramic laminate. In the method for manufacturing a laminated electronic component, wherein the conductive paste for the internal electrodes comprises at least a metal powder, an organic binder and an organic solvent, the conductive paste for the internal electrodes further contains a carbide powder. A method for manufacturing a laminated electronic component, characterized in that the manufactured product is used. 8. A step of applying a conductive paste for an external electrode to an end portion of the ceramic laminated body, wherein a metal powder, a carbide powder, an organic binder and an organic solvent are used as the conductive paste for the external electrode. The method for manufacturing a laminated electronic component according to claim 7, wherein at least one having: is used. 9. The method for manufacturing a laminated electronic component according to claim 7, wherein the wetting angle of the carbide with respect to the metal is 0 to 90 degrees. 10. The compound according to claim 7, wherein the carbide is a compound that changes into a solid oxide by firing.
10. The method for manufacturing a laminated electronic component according to any of 9. 11. The content of the carbide is 0.05 to 15
It is wt%, The manufacturing method of the laminated electronic component in any one of Claims 7-10. 12. The method for manufacturing a laminated electronic component according to claim 7, wherein the metal is Ni and the carbide is TiC. 13. The method for manufacturing a laminated electronic component according to claim 7, wherein the metal is Cu and the carbide is WC.