JP2000285733A - Manufacture of conductive powder and conductive paste and electronic component using them - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a high reliability conductive paste used for forming an electrode of an electronic component and provide a manufacturing method of the conductive powder used for the conductive paste. SOLUTION: A conductive metal is reduction-deposited on the surface of glass frit by using glass frits, a metal salt aqueous solution and a reducing agent, the glass frit surface is covered with the conductive metal to manufacture conductive powder, and a conductive paste kneaded with the conductive powder, a binder and a solvent is applied and baked on an electronic component element to form an electrode.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a conductive powder for forming an electrode on an electronic component used in various electronic devices, and a conductive paste and an electronic component using the same.

[0002]

2. Description of the Related Art Conventionally, a conductive paste used for an electronic component is produced by mixing and dispersing a metal powder such as silver, copper, nickel, etc., a glass frit, a binder, a solvent, and the like, and forming this into an electronic component body. It was common to form electrodes by coating and baking.

[0003]

The conventional conductive paste has a specific gravity of metal powder and glass frit contained therein.
There is a problem that it is difficult to uniformly mix and disperse the particles due to a large difference in the particle shape, and that the electronic components formed using the same have large variations in the flatness of the electrode surface and the electrode bonding strength.

An object of the present invention is to eliminate the above-mentioned conventional disadvantages and to provide a conductive paste which is homogeneously mixed and dispersed.

[0005]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention uses a conductive powder obtained by coating a metal on the surface of a glass frit and replacing it with a conventional glass frit and metal powder, and bonding it to the powder. A conductive paste is prepared by mixing and dispersing agents, solvents and the like.

As a result, a conductive paste in which the glass frit and the metal powder are mixed and dispersed more homogeneously than in the method of individually mixing the glass frit and the metal powder can be obtained. Can be reduced.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION According to the first aspect of the present invention, a conductive metal is reduced and precipitated on the surface of a glass frit using a glass frit, an aqueous solution of a metal salt, and a reducing agent. This is a method for producing a conductive powder for coating the surface, in which a glass frit is dispersed in an aqueous solution of a conductive metal salt such as an aqueous solution of silver nitrate, for example, and a glass frit is formed by an electroless plating method in which a reducing agent such as formalin is introduced. A conductive powder whose surface is coated with a conductive metal can be easily obtained. By changing the mixing ratio of the glass frit, the aqueous solution of the metal salt, and the reducing agent, a conductive coating film having an arbitrary thickness can be formed on the surface of the glass frit.

According to a second aspect of the present invention, there is provided a conductive paste comprising the conductive powder according to the first aspect, a binder and a solvent, wherein a surface of a glass frit is previously coated with a conductive metal. By using the conductive powder, it is possible to obtain a conductive paste in which a glass frit having a specific gravity difference and a particle shape difference and a conductive metal are uniformly dispersed as compared with the conventional method.

According to a third aspect of the present invention, there is provided the conductive paste according to the second aspect, wherein the conductive metal covering the surface of the glass frit is silver, which covers the surface of the glass frit. It specifies the material of the conductive metal.

According to a fourth aspect of the present invention, there is provided an electronic component in which the conductive paste according to any one of the second to third aspects is applied to an electronic component body and baked to form an electrode. This is because a conductive paste in which the glass frit and the conductive metal are uniformly dispersed is obtained by using a conductive powder in which the surface of the glass frit is coated with a conductive metal in advance, and this is obtained by a method such as screen printing. An excellent electronic component having a flat electrode surface formed by applying and baking on the surface of the electronic component body and having a small variation in the bonding strength between the element body and the electrode can be obtained.

Hereinafter, specific embodiments of the present invention will be described.

First, the average particle diameter is 6 μm and the specific surface area is 1.7.
20.1 g of 7 m ² / g borosilicate glass frit, 80
% Hydrazine hydrate and 1350 ml of water were stirred, mixed and dispersed by a mixer.
An aqueous silver nitrate solution in which 5 g is dissolved in 270 ml of water is charged, and silver is deposited on the surface of the glass frit by an electroless plating method.

Next, the glass frit was sufficiently washed with water and dried at a temperature of 70 ° C. for 20 hours to obtain a conductive glass frit powder whose surface was coated with silver.

FIG. 1 shows scanning electron micrographs of a glass frit before treatment and FIG. 2 shows a glass frit having silver coated on its surface.

FIG. 2 shows that the surface of the glass frit is uniformly coated with the precipitated silver particles. Then
13.5 g of a vehicle containing ethyl cellulose as a main component was added to 86.5 g of a silver-coated glass frit and kneaded with a three-roll mill to prepare a conductive paste. Further, as a comparative example, 70.0 g of silver powder and 1 glass frit were prepared by a conventional method.
Vehicle 1 containing 6.5 g of ethyl cellulose as a main component
A conductive paste prepared by adding 3.5 g and kneading with a three-roll mill was also prepared.

Each conductive paste was applied to a disk-shaped voltage non-linear resistance element by screen printing, dried, and baked at a temperature of 800 ° C. to form an electrode.

FIG. 3 shows the results of measuring the surface roughness of the electrodes of the fabricated voltage non-linear resistance element.

As shown in FIG. 3, the conductive paste of the present invention has a Rmax of 6.8 μm, which is equal to Rm of the conventional conductive paste.
It can be seen that it is much smaller than ax = 12.5 μm.

FIG. 4 shows the surface of the electrode of the voltage non-linear resistance element to which the conductive paste of the present invention is baked, and FIG. 5 shows the surface of the electrode of the conventional voltage non-linear resistance element to which the conductive paste is baked. 3 shows a scanning electron micrograph.

As shown in FIGS. 4 and 5, it can be seen that the electrode surface of the conductive paste of the present invention is more uniform.

Next, 0.8 mm is applied to each of the electrode surfaces.
After soldering the tinned copper wire of φ, the peel strength between the voltage non-linear resistance element and the electrode was measured using a tensile tester, n = 30 pieces, and the results are shown in (Table 1).

[0022]

[Table 1]

As shown in Table 1, it can be seen that the conductive paste of the present invention has improved peel strength and its variation.

The material and the mixing ratio of the glass frit and the reducing agent shown in the present embodiment, or the material and the mixing ratio of the vehicle are not particularly limited.

In addition, the conductive metal is not limited to silver. For metals used as conductive pastes such as copper and nickel, the surface of the glass frit is similarly coated on the surface of the glass frit by a generally known electroless plating method. Alternatively, a conductive powder coated with nickel is obtained, and the same effect as the present invention can be obtained by preparing a conductive paste using the same.

[0026]

As described above, according to the present invention, a conductive powder in which a glass frit and a conductive metal are uniformly dispersed is used by using a conductive powder obtained by depositing and coating a conductive metal on the surface of a glass frit. A paste is obtained. In addition, by forming electrodes on the electronic component body using this conductive paste, the flatness of the electrode surface after application and baking, the reduction in the bonding strength between the electronic component body and the electrode are reduced, and the reliability is excellent. Electronic components can be provided.

[Brief description of the drawings]

FIG. 1 is a scanning electron micrograph of a glass frit powder used for a conductive powder of the present invention.

FIG. 2 is a scanning electron micrograph showing a state in which silver particles are precipitated on the surface of the glass frit powder.

FIG. 3 is a view showing the surface roughness of an electrode formed on a surface of an electronic component body using the conductive paste of the embodiment and a comparative example.

FIG. 4 is a scanning electron micrograph of an electrode formed on an electronic component body surface using a conductive paste produced by the method of the present invention.

FIG. 5 is a scanning electron micrograph of an electrode formed on an electronic component body surface using a conductive paste prepared by a conventional method.

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Claims (4)

[Claims] 1. A method for producing a conductive powder in which a conductive metal is reduced and precipitated on the surface of a glass frit using a glass frit, an aqueous solution of a metal salt, and a reducing agent, and the surface of the glass frit is coated with the conductive metal. 2. A conductive paste comprising the conductive powder according to claim 1, a binder and a solvent. 3. The conductive paste according to claim 2, wherein the conductive metal covering the surface of the glass frit is silver. 4. The electronic component body according to claim 2 or claim 3.
An electronic component having an electrode formed by applying and baking the conductive paste according to 1.