KR101333342B1 - Method of forming a metal powder and method of manufacturing a conductive paste using the same - Google Patents

Abstract

In the method for forming a metal powder having a core cell structure, after dissociating the non-noble metal precursor into the solvent, the first carbon precursor is supplied to the solvent to form a spray solution in which the non-noble metal and the carbon are dissolved. The spray solution is then synthesized via a spray pyrolysis process to form a carbon / metal composite consisting of carbon and non-noble metals.

Description

METHODS OF FORMING A METAL POWDER AND METHOD OF MANUFACTURING A CONDUCTIVE PASTE USING THE SAME

The present invention relates to a method for forming a metal powder and a method for producing a metal paste made of the metal powder, and more particularly, the present invention relates to a method for forming a metal powder consisting of non-noble metal particles and a conductive paste using the metal powder. It relates to a method of manufacturing.

In general, various kinds of electronic components such as semiconductor devices, display devices or solar cell devices are manufactured including a patterning process of forming a conductive pattern on a substrate such as a wafer or glass.

In the patterning process, a method of forming a conductive pattern by coating a metal entirely on a substrate and then etching unnecessary portions and a method of directly printing a paste having conductivity on the substrate according to the conductive pattern are used.

Among these, the paste used in the printing method includes a metal powder for providing conductivity, a binder for adhering the metal powder to a substrate, and a solvent for providing fluidity of the paste.

Here, in order to prevent the metal powder from becoming an insulator due to the oxide film formed on the surface, precious metal particles such as silver, which are difficult to form an oxide film on the surface, are used.

Therefore, in recent years, as the price of precious metals such as silver is rising, the cost of manufacturing the paste is gradually increasing.

It is an object of the present invention to provide a method of forming a metal powder using non-noble metal particles that can replace the precious metal.

Another object of the present invention is to provide a method for producing a conductive paste using the metal powder.

In order to achieve the above object of the present invention, in the method of forming the metal powder according to an embodiment of the present invention, by dissociating a non-noble metal precursor in a solvent, and supplying a first carbon precursor to the solvent to the non-noble metal and carbon Form a dissolved spray solution. The spray solution is synthesized through a spray pyrolysis process to form a carbon / metal composite composed of carbon and non-noble metals. Here, the non-noble metal precursor may include copper nitrate or nickel nitrate.

In one embodiment of the present invention, the second carbon precursor may be further dissociated in the solvent. Here, the first carbon precursor may include citric acid, and the second carbon precursor may include sucrose. In addition, the citric acid and the non-noble metal may be adjusted to a molar ratio of 0.1: 1.0 to 1.5: 1.0. On the other hand, the sucrose and the non-noble metal may be adjusted to a molar ratio of 0.1: 1.0 to 0.4: 1.0.

In one embodiment of the present invention, the non-noble metal may be made of any one or at least two alloys of copper (Cu), aluminum (Al), nickel (Ni), zinc (Zn), iron (Fe). .

In one embodiment of the present invention, in order to form the carbon / metal complex, after the ultrasonic wave is supplied to the spray solution to generate a droplet, the droplet is supplied into the reactor to be powdered. The powdered particles may then be filtered to recover the carbon / metal composite to form the carbon / metal composite.

In order to achieve the above object of the present invention, in the method of manufacturing the conductive paste according to the embodiment of the present invention, after dissociating the non-noble metal precursor in the first solvent, the first carbon precursor is supplied to the first solvent To form a spray solution in which the non-noble metal and carbon are dissolved. The spray solution was synthesized through a spray pyrolysis process to form a metal powder having a core cell structure composed of a carbon / metal composite composed of carbon and non-noble metals, and then mixed with the binder and the second solvent to form a conductive powder. To manufacture. Here, the binder may include an epoxy resin and an ester.

According to the method of forming the metal powder and the method of manufacturing the metal paste using the metal powder, oxidation of the metal powder can be prevented by forming a carbon metal / carbon composite with respect to the metal powder used to form the conductive pattern. In addition, the metal powder and the metal paste including the same may be manufactured by replacing the precious metal with a non-noble metal.

1 is a cross-sectional view showing a metal powder according to a first embodiment of the present invention.
2 is a cross-sectional view showing a metal powder according to a comparative example of the present invention.

Hereinafter, a method of forming a metal powder and a method of manufacturing a metal paste according to embodiments of the present invention will be described in detail with reference to the accompanying drawings. The present invention is capable of various modifications and various forms, and specific embodiments are illustrated in the drawings and described in detail in the text. It should be understood, however, that the invention is not intended to be limited to the particular forms disclosed, but includes all modifications, equivalents, and alternatives falling within the spirit and scope of the invention.

The terms first, second, etc. may be used to describe various components, but the components should not be limited by the terms. The terms are used only for the purpose of distinguishing one component from another. For example, without departing from the scope of the present invention, the first component may be referred to as a second component, and similarly, the second component may also be referred to as a first component.

The terminology used herein is for the purpose of describing particular example embodiments only and is not intended to be limiting of the present invention. Singular expressions include plural expressions unless the context clearly indicates otherwise. In this application, the terms "comprises", "having", and the like are used to specify that a feature, a number, a step, an operation, an element, a part or a combination thereof is described in the specification, But do not preclude the presence or addition of one or more other features, integers, steps, operations, components, parts, or combinations thereof.

On the other hand, unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Terms such as those defined in commonly used dictionaries are to be interpreted as having a meaning consistent with the contextual meaning of the related art and are to be interpreted as either ideal or overly formal in the sense of the present application Do not.

How to Form Metal Powder

First, the non-noble metal precursor is dissociated in a solvent to form non-noble metal particles dissociated in the solvent. Examples of the non-noble metal precursor include nickel nitrate or copper nitrate. Examples of the solvent include de-ionized water. When the non-noble metal precursor includes nickel nitrate or copper nitrate, when the non-noble metal precursor is dissociated in a solvent, nickel or copper may be dissociated in the solvent. The nickel nitrate or copper nitrate has a relatively high solubility in the pure water.

The non-noble metal particles are made of a metal having better electrical conductivity than other metals and having relatively better economic efficiency than the precious metal. For example, the non-noble metal particles 10 may be made of any one or at least two alloys of copper (Cu), aluminum (Al), nickel (Ni), zinc (Zn), iron (Fe).

Among the non-noble metal particles, copper (Cu) having an electrical conductivity of about 94% is preferable as compared with silver (Ag) having excellent electrical conductivity among precious metals. Such non-noble metal particles are easily oxidized when exposed to the air due to their properties, and an oxide film may be formed on the surface.

Subsequently, the first carbon precursor is supplied to the solvent to form a spray solution in which the non-noble metal and the carbon are dissolved. The first carbon precursor may include, for example, citric acid. When the first carbon precursor is supplied to the solvent, the first carbon precursor is dissociated to supply carbon into the solvent.

Here, the citric acid and the non-noble metal may be adjusted in a molar ratio of 0.1: 1.0 to 1.5: 1.0.

For example, when the non-noble metal is copper, the pure copper phase appeared when the molar ratio of citric acid and copper exceeded 1.5. Particles of spherical and irregular shape were produced when the molar ratio of citric acid and copper was 0.7: 0.1.

In addition, when the molar ratio of citric acid and copper exceeds 1.5, the size of the produced metal particles also tended to increase. However, the shape of the metal particles changed as the shape of the carbon particles in which the nano metal particles are dispersed. The metal particles may not have a core cell structure, but may have a carbon structure in which nano metal particles are dispersed.

Thus, a spray solution containing a non-noble metal and carbons is formed in the solvent.

The spray solution is then synthesized via a spray pyrolysis process to form a carbon / metal composite consisting of carbon and non-noble metals. The carbon / metal composite may have a core cell structure including a core made of a non-noble metal and a cell made of carbon surrounding the core.

In the spray pyrolysis process for forming the carbon / metal composite, first, ultrasonic waves are supplied to the spray solution to generate droplets. The ultrasonic waves may have a frequency of 1.7 MHz, for example. In addition, droplets may be generated using a plurality of ultrasonic vibrators having the frequency. The resulting droplets are then fed into the reactor. At this time, the carrier gas for transporting the droplets include nitrogen (N ₂ ) gas. In addition, the flow rate of the carrier gas may be adjusted to 5 to 15 L / min.

In the reactor, the droplets may be powdered through a drying / pyrolysis and crystallization process. The reactor interior can be adjusted to a temperature range of 700 to 1,100 ° C. In addition, the material of the reactor may be made of quartz.

Subsequently, the powdered particles may be filtered to recover a carbon / metal composite having a uniform size. In this case, a Teflon filter may be used to filter the powdered particles.

In one embodiment of the present invention, a washing process, a filtration process and a drying process may be additionally performed to remove remaining salts. The cleaning process may be performed using deionized water. The filtration process may be carried out using a vacuum filtering device. In addition, the banjo process may be performed at a temperature of about 100 to 150 ° C in a drying oven.

In one embodiment of the present invention, before performing the spray pyrolysis process, the second carbon precursor may be further dissociated in the solvent. The second carbon precursor may include sucrose. Here, the sucrose and the non-noble metal may be adjusted in a concentration ratio of 0.1: 1.0 to 0.4: 1.0.

Conductive Paste Manufacturing Method

In order to prepare the conductive paste, a carbon / metal composite is first formed. The carbon / metal composite may have a core cell structure including a core made of a non-noble metal and a cell made of carbon surrounding the core.

The carbon / metal composite is fed to the second solvent together with the binder. Examples of the binder may include an epoxy resin or an ester. Accordingly, the conductive paste may be prevented from agglomerating itself when printed on the object, and thus printing may be appropriately performed, and when the subsequent heat treatment process is performed at a low temperature such as about 100 ° C., The conductivity can be maintained.

The second solvent is mixed with the binder and the metal powder made of the carbon / metal composite. The second solvent provides fluidity of the conductive paste in a printing process of printing on the object using the conductive paste. As a result, the conductive paste may be spread to have a desired width and thickness on the object. Unlike the binder, the second solvent may be removed in a heat treatment step of subsequently heat treating the conductive paste. The second solvent may include, for example, butylcellussolve.

Example 1

A carbon / nonmetallic composite was synthesized to obtain metal particles of a sphere having a radius (D ₅₀ ) of 1.5 to 2.2 μm obtained through 1,100 ° C. heat treatment. The metal particles form a core cell structure including a core made of copper particles and a cell made of carbon surrounding the core. A conductive pate is prepared from 80 wt.% Of the powder of the metal particles, 8 wt.% Of a bisphenol A resin as a binder, and a residual amount of a butyl cellulsolve solvent as a solvent. The conductive paste has a viscosity of 80,000 to 100,000 cPs. After the electrode circuit pattern is printed on the polyimide substrate by using flat screen printing using the conductive paste, heat treatment is performed at 200 ° C. for 20 minutes. Subsequently, an etching process is performed in a 5% aqueous sulfuric acid solution for 1 minute, so that the electrode circuit pattern has a surface resistance of 7 to 8 Ω / □.

The plated layer is formed by electroplating the printed circuit for 30 minutes at a current density of 3.3 A / dm 2. The plating layer has a thickness of 18 to 20 μm and has a surface resistance of 1.1 mΩ / □.

Comparative Example

Spray solution was prepared as follows to prepare a non-noble metal / carbon composite in which non-noble metal particles are dispersed therein. First, dissolve 0.1 M of a metal precursor such as metal acetate or metal nitrate in 500 ml of distilled water. The dissociation is performed by adding 0.5 M of sucrose, which is the first carbon precursor, to the solution in which the metal precursor is completely dissociated. When the first carbon precursor is dissolved, sodium hydrogen carbonate (NaHCO ₃ ) is added by 0.5 M, and the mixture is added, and slowly adding 10 ml of nitric acid (HNO ₃ ) to form a clear solution to form a spray solution. Subsequently, the spray solution is synthesized through a spray pyrolysis process to form metal particles composed of non-noble metal / carbon composites in which non-noble metal particles are dispersed therein. Subsequently, an electroconductive pate is prepared from 80 wt.% Of the powder of the metal particles, 8 wt.% Of a bisphenol A resin as a binder, and a residual amount of a butyl cellulsolve solvent as a solvent. After the electrode circuit pattern is printed on the polyimide substrate by using flat screen printing using the conductive paste, heat treatment is performed at 200 ° C. for 20 minutes. Subsequently, the etching process was performed in a 5% aqueous sulfuric acid solution for 1 minute, so that the electrode circuit pattern had a surface resistance of several MΩ / □.

While the present invention has been described in connection with what is presently considered to be practical and exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.

Claims (10)

Dissociating the non-noble metal precursor into the solvent;
Supplying a first carbon precursor and a second carbon precursor to the solvent to form a spray solution in which non-noble metals and carbons are dissolved; And
Synthesizing the spray solution through a spray pyrolysis process to form a carbon / metal composite composed of carbon and non-noble metals,
The first carbon precursor includes citric acid, and the second carbon precursor comprises sucrose (sucrose). The method of claim 1, wherein the non-noble metal precursor comprises copper nitrate or nickel nitrate. delete delete The method of claim 1, wherein the citric acid and the non-noble metal are adjusted in a molar ratio of 0.1: 1.0 to 1.5: 1.0. The method of claim 1, wherein the sucrose and the non-noble metal are controlled at a molar ratio of 0.1: 1.0 to 0.4: 1.0. The core cell of claim 1, wherein the non-noble metal is made of one or at least two alloys of copper (Cu), aluminum (Al), nickel (Ni), zinc (Zn), and iron (Fe). Method for forming a metal powder having a structure. The method of claim 1, wherein the forming of the carbon / metal composite comprises:
Supplying ultrasonic waves to the spray solution to generate droplets;
Powdering the droplets by feeding them into the reactor; And
And filtering the powdered particles to recover a carbon / metal composite. Dissociating the non-noble metal precursor into the first solvent;
Supplying a first carbon precursor and a second carbon precursor to the first solvent to form a spray solution in which non-noble metals and carbons are dissolved;
Synthesizing the spray solution through a spray pyrolysis process to form a metal powder having a core cell structure composed of a carbon / metal composite composed of carbon and non-noble metals; And
Mixing the metal powder with a binder and a second solvent,
Wherein said first carbon precursor comprises citric acid and said second carbon precursor comprises sucrose. The method of claim 9, wherein in the mixing of the binder and the solvent, the binder comprises an epoxy resin and an ester.

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