KR100567444B1 - Composite metal powder manufaturing method of silver and copper - Google Patents

Abstract

The present invention relates to a method for producing a composite metal powder of silver and copper, the object of which is to generate a high partial pressure of hydrogen gas and to solve the problem due to the use of hydrogen gas in the production of silver-copper composite metal powder Since it does not require a clave, it does not require much initial equipment cost and also has a strong reducing power generated when using formaldehyde or hydrazine aqueous solution as before. Therefore, the particle size of the composite metal powder produced when reducing and depositing silver and copper ions becomes larger and causes aggregation In this very deep paste, it is difficult to uniformly disperse the paste and its toxicity is harmful to the human body, and ascorbic acid is used to avoid the disadvantage that the cost of waste water treatment is not high. It is possible to control, which results in a fine average particle diameter and reduced precipitated composite metal powder. Are not mutually agglomerated paste during manufacture is possible to provide a uniform dispersion (銀) and copper method of manufacturing a composite metal powder.

The composition of the present invention is a method of producing a composite metal powder of silver and copper, in which silver nitrate is dissolved in pure water to form an aqueous solution of silver nitrate, followed by stirring with copper sulfate. Adding an aqueous copper sulfate solution dissolved in pure water to prepare an aqueous solution of a mixture of silver and copper; Stirring the mixed aqueous solution to form a mixed complex of silver and copper by adding ammonia water until the pH of the solution is adjusted to 11 or more; The solution in which the mixed complex compound of silver and copper is formed is heated and maintained at a constant temperature while stirring and reducing and simultaneously depositing copper and silver ions by adding an aqueous solution of ascorbic acid, followed by filtration, washing and drying. It characterized in that the method for producing a composite metal powder of silver and copper having an average particle diameter of 1 ~ 5㎛.

Silver, copper, conductive paste, filler, ascorbic acid

Description

Composite metal powder manufaturing method of silver and copper             

1 is a manufacturing process chart of the composite metal powder of the present invention silver and copper,

2 is a scanning electron micrograph of the composite metal powder prepared in Example 1 of the present invention;

Figure 3 is a scanning electron micrograph of the composite metal powder prepared in Example 2 of the present invention,

Figure 4 is a scanning electron micrograph of the composite metal powder prepared in Example 3 of the present invention,

5 is a scanning electron micrograph of the composite metal powder prepared in Comparative Example 1;

6 is a scanning electron micrograph of the composite metal powder prepared in Comparative Example 2.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a composite metal powder of silver and copper, and more particularly, to a method for producing a composite metal powder of silver and copper, which is used as a conductive filler when preparing a conductive paste. It is about.

Typical applications of conductive pastes are used as circuits or electrode materials for small electronic components such as hybrid ICs, MLCCs, multilayer circuit boards, and the like. Recently, these electronic components are not only showing the tendency of light and thin, but also the development of technology for high density, large capacity, and reduction of manufacturing cost are actively progressing.

Therefore, the conductive paste which is an electrode material is also urgently required to improve its performance and reduce manufacturing cost.

Until now, the most commonly used conductive paste for electrode material of MLCC or multilayer circuit board is silver paste. However, silver paste has shown limitations in the fabrication of ultrafine circuits having a width and spacing of 10 μm or less due to ion migration. Furthermore, silver paste is a precious metal paste, which increases the manufacturing cost of small electronic components such as MLCC. It is the cause.

An alternative material for overcoming this problem is a paste using a composite metal powder of silver and copper, which possesses excellent conductivity and thus has high reliability and economic advantages.

The composite metal powder of silver and copper used for this purpose should have high recovery rate because silver nitrate, which is 99.9% or more of purity, is expensive as a noble metal compound, and the particle shape of the manufactured composite metal powder of silver and copper should be uniform. The average particle size should be 1 ~ 5㎛ and the particle size distribution width should be narrow.

Conventionally, as a method for producing a composite metal powder of silver and copper, silver nitrate and copper sulfate having a purity of 99.9% or more are dissolved in pure water, and then a solution of silver and copper is prepared by adding a copper sulfate aqueous solution while stirring the silver nitrate aqueous solution. The solution was charged into an autoclave, and the reactor was heated to maintain a temperature of 80 ° C., followed by injecting hydrogen gas with stirring to maintain a partial pressure of hydrogen at 20 to 30 kg / cm 2 for 60 minutes, followed by cooling and filtration. , Washing and drying.

Since the conventional manufacturing method uses an autoclave, it requires a lot of initial investment due to equipment cost and equipment cost, and it is difficult to control the particle size and particle shape because the reduction reaction proceeds at a high speed, and the aggregation phenomenon of the particles is very severe. There is this.

An object of the present invention for solving the above problems is that the production of silver-copper composite metal powder does not require a high partial pressure of hydrogen gas due to the use of hydrogen gas, and the need for autoclave to solve this problem is high. Does not take

In addition, since the reducing power generated when using formaldehyde or hydrazine aqueous solution as in the prior art, the particle size of the composite metal powder produced when reducing and precipitating silver and copper ions is large, and the coagulation phenomenon is so severe that it is difficult to uniformly disperse and toxic in paste production. Strong As it is not only harmful to human body, but also has no disadvantage of high cost of waste water treatment, it is possible to control the particle size and particle size of precipitated particles because the reduction precipitation reaction is not fast by using Ascorbic Acid. The present invention provides a method for producing a composite metal powder of silver and copper, which can be uniformly dispersed during paste production because the reduced-precipitated composite metal powder does not aggregate with each other.

When described in detail with reference to the accompanying drawings, the configuration and the operation of the embodiment of the present invention to achieve the object as described above and to perform the task for eliminating the conventional drawbacks.

1 illustrates a process chart of the production of a composite metal powder of silver and copper according to the present invention. Referring to the manufacturing process of the present invention, the silver nitrate and copper sulfate having a purity of 99.9% or more are dissolved in pure water, followed by stirring with an aqueous solution of silver nitrate. Aqueous copper sulfate solution was added thereto to prepare an aqueous solution of a mixture of silver and copper, and then the solution was added with ammonia water until the pH reached 11 or higher to form a complex compound of silver and copper, and then the solution was heated. While maintaining the solution at a constant temperature, adding an aqueous solution of ascorbic acid dissolved in pure water, reducing and precipitating copper and silver ions at the same time, filtering, washing, and drying the silver and having an average particle diameter of 1-5 μm It is characterized by a method for producing a composite metal powder of copper.

The aqueous solution of silver nitrate is mixed with 1-39g of silver nitrate dissolved in 1L pure water, and the copper sulfate solution contains 1-39g of copper sulfate dissolved in 1L pure water, but the total content of silver nitrate and copper sulfate based on 2L mixed solution is 40g or less. Characterized in that adjusted to be. Therefore, if the total amount of the mixed solution is 4L, the total content of silver nitrate and copper sulfate is adjusted to be 80g or less, and if it is 8L, it has a proportional relationship.

The reason for the numerical limitation as described above is that when the total content is more than 40 g, the particles are aggregated and the size of the particles is coarse, making it difficult to achieve the object of the present invention.

The ascorbic acid is adjusted to add an aqueous solution in which 15 g of ascorbic acid is dissolved in 1 L of pure water based on a mixed solution in which 40 g of a mixture of silver nitrate and copper sulfate is dissolved in 2 L of pure water. It is done.

Therefore, a mixture of silver nitrate and copper sulfate has a proportional relationship such that 30 g / 2 L is dissolved in a mixture of 80 g / 4 L and 60 g / 4 L is dissolved in a mixture of silver nitrate and copper sulfate 160 g / 8 L.

The reason for the limited value of this value and the reason for the selection of ascorbic acid can be used in the formaldehyde and hydrazine aqueous solutions. In the preparation of this very deep sea paste, since it is difficult to uniformly disperse and strong in toxicity, it is not only harmful to the human body, but also has a disadvantage of high wastewater treatment cost.

In the step of controlling the precipitation ratio of the final silver and copper in the step of preparing a mixture solution of silver and copper, it is characterized in that the desired amount of precipitation is controlled by adjusting the mixing ratio of silver nitrate and copper sulfate.

When the pH is 11 or more, the numerical value of the complex ion Ag (NH ₃ ) ^{+ 2} and Cu (NH ₃ ) ₄ ⁺² ) is satisfied. Of course, complex ions of silver and copper begin to form from pH 10, but complete complex ions are difficult to form and complex ions form completely from pH 11 and above. Maintaining the pH above achieves the object of the present invention but requires an unnecessary excess amount of ammonia water.

In addition, the reaction proceeds for 60 minutes when the ascorbic acid is added, which is a time required for the complete reduction and precipitation of silver and copper ions simultaneously in a mixed aqueous solution of silver and copper.

Forming a complex compound (Complex Compound) in the above and then maintaining the temperature at 40 ~ 50 ℃ when the solution is heated and stirred because of the limitation of this temperature is because the reaction proceeds most stably in this section.

Hereinafter, preferred examples of the present invention and comparative examples.

Example  One

30 g of silver nitrate with a purity of 99.9% and 10 g of copper sulfate were placed in two Pyrex containers each having a capacity of 3 L, and then 1 L of pure water was added thereto to completely dissolve the solution.

The solution was added with ammonia water until the pH reached 11 or higher to form a complex compound of silver and copper. Then, the solution was heated to maintain a temperature of 50 ° C. and stirred with 15 g of ascorbic acid in 1 l of pure water. 60 minutes by adding the dissolved aqueous solution was carried out to reduce and precipitate copper and silver ions at the same time, and then filtered, washed and dried to prepare 21.4 g of a composite metal powder of silver and copper.

The particle shape and average particle size of the prepared electron microscope (SEM) and particle size analyzer were investigated. The particle shape was uniform (see Fig. 2) with excellent dispersion state, and the average particle size was 1.6 µm and the content of silver was 88.3%, copper. The content of was 11.7%

Example  2

20 g of silver nitrate with a purity of 99.9% and 20 g of copper sulfate were placed in two Pyrex containers each having a capacity of 3 L, and then 1 L of pure water was completely dissolved therein.

The solution was added with ammonia water until the pH reached 11 or higher to form a complex compound of silver and copper. Then, the solution was heated to maintain a temperature of 50 ° C. and stirred with 15 g of ascorbic acid in 1 l of pure water. 60 minutes by adding the dissolved aqueous solution was carried out to reduce and precipitate copper and silver ions simultaneously, and then filtered, washed and dried to prepare 17.6 g of a composite metal powder of silver and copper.

As a result of investigating the particle shape and average particle size by the SEM and particle size analyzer, the particle shape was uniform form (see Fig. 3) with excellent dispersion state, the average particle size was 3.5㎛ and the content of silver was 71.6%, copper The content of was 28.4%

Example  3

10 g of silver nitrate with a purity of 99.9% and 30 g of copper sulfate were put into two Pyrex containers each having a capacity of 3 L, and then 1 L of pure water was completely dissolved therein.

The solution was added with ammonia water until the pH reached 11 or higher to form a complex compound of silver and copper. Then, the solution was heated to maintain a temperature of 50 ° C. and stirred with 15 g of ascorbic acid in 1 l of pure water. The reaction was carried out for 60 minutes by adding the dissolved aqueous solution to reduce and precipitate copper and silver ions at the same time, and then filtered, washed and dried to prepare 13.8 g of a composite metal powder of silver and copper.

The particle shape and average particle size of the prepared electron microscope (SEM) and particle size analyzer were examined. The particle shape was uniform (see Fig. 4) with excellent dispersion state, and the average particle size was 1.6 μm. The content of was 54.4%.

Comparative example  One

30 g of silver nitrate with a purity of 99.9% and 10 g of copper sulfate were placed in two Pyrex containers each having a capacity of 3 L, and then 1 L of pure water was added thereto to completely dissolve the solution.

After charging the solution into an autoclave with a volume of 3 L, the reactor was heated to maintain a temperature of 80 ° C., and then hydrogen gas was injected with stirring to maintain a partial pressure of hydrogen at 30 kg / cm 2 for 60 minutes. Cooling, filtration, washing and drying produced 21.4 g of a composite metal powder of silver and copper.

As a result of investigating the particle shape and the average particle size by the SEM and the particle size analyzer, the particle shape was irregular shape with severe aggregation state (see Fig. 5), the average particle size was 8.6㎛, the content of silver was 88.3%, the content of copper Was 11.7%.

Comparative example  2

20 g of silver nitrate with a purity of 99.9% and 20 g of copper sulfate were put into two Pyrex containers each having a capacity of 3 L, and then 1 L of pure water was completely dissolved therein.

After charging the solution into an autoclave with a volume of 3 L, the reactor was heated to maintain a temperature of 80 ° C., and then hydrogen gas was injected with stirring to maintain a partial pressure of hydrogen at 30 kg / cm 2 for 60 minutes. Cooling, filtration, washing and drying produced 17.6 g of the composite metal powder of silver and copper.

As a result of investigating the particle shape and average particle size of the prepared composite metal powder by scanning electron microscope (SEM) and particle size analyzer, the particle shape was irregular shape with severe aggregation state (see Fig. 6), and the average particle size was 9.5㎛ and the content of silver was 71.6%. , The content of copper was 28.4%

The present invention is not limited to the above-described specific preferred embodiments, and various modifications can be made by any person having ordinary skill in the art without departing from the gist of the present invention claimed in the claims. Of course, such changes will fall within the scope of the claims.

As described above, the present invention does not require an autoclave or the like to generate a high partial pressure of hydrogen gas and to solve the high pressure due to not using hydrogen gas when preparing the silver-copper composite metal powder as in the prior art, and thus does not require much initial equipment cost. In addition, since the reduction precipitation reaction is not fast, it is possible to control the particle size and particle size of the precipitated particles, and thus, the average particle diameter is fine, and the reduced-precipitated composite metal powder does not aggregate with each other, thereby making it possible to uniformly disperse the paste. It is an invention which is expected to be greatly used in the industry as a useful invention.

Claims (5)

In the manufacturing method of the composite metal powder of silver and copper, Dissolving silver nitrate in pure water to form an aqueous solution of silver nitrate, followed by stirring, and adding copper sulfate aqueous solution in which copper sulfate was dissolved in pure water to prepare an aqueous solution of a mixture of silver and copper. Wow; Stirring the mixed aqueous solution to form a mixed complex of silver and copper by adding ammonia water until the pH of the solution is adjusted to 11 or more; After heating and maintaining the temperature of the solution in which the mixed complex of silver and copper is formed at a constant temperature, stirring and adding an ascorbic acid aqueous solution while simultaneously reducing and precipitating copper and silver ions and then filtering, washing and drying the same A method for producing a composite metal powder of silver and copper, comprising the steps of preparing a composite metal powder of silver and copper having an average particle diameter of 1 to 5 µm. The method of claim 1, The aqueous solution of silver nitrate is mixed with 1-39 g of silver nitrate dissolved in 1 L of pure water, and the copper sulfate solution is mixed with 1-39 g of copper sulfate dissolved in 1 L of pure water. A method for producing a composite metal powder of silver and copper, which has been adjusted. The method according to claim 1 or 2, The ascorbic acid is adjusted to add an aqueous solution in which 15 g of ascorbic acid is dissolved in 1 L of pure water based on a mixed solution in which 40 g of a mixture of silver nitrate and copper sulfate is dissolved in 2 L of pure water. A method for producing a composite metal powder of silver and copper. The method according to claim 1 or 2, In the final step of controlling the precipitation ratio of silver and copper, a method of controlling a desired amount of precipitation by adjusting the mixing ratio of silver nitrate and copper sulfate in the step of preparing an aqueous solution of the mixture of silver and copper ) And a method for producing a composite metal powder of copper. The method of claim 1, Forming the complex compound (Complex Compound) and then stirring the solution while maintaining the temperature at 40 ~ 50 ℃ when heating the solution characterized in that the composite metal powder of silver and copper.

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