KR101239391B1 - Method of manufacturing fine cupper powders for electronic materials with easily size control - Google Patents

Abstract

Disclosed is a method for producing copper powder for electronic materials, the particle size of which is easy to control.
Method for producing a fine copper powder for an electronic material according to the present invention comprises the steps of (a) preparing a Pd suspension containing palladium (Pd) particles as a seed (seed); (b) adding Cu ₂ O to the Pd suspension to form a Cu ₂ O slurry having a concentration of Cu ₂ O of 1.25-40 g / L; And (c) supplying N ₂ H ₄ to the Cu ₂ O slurry as a reducing agent to reduce Cu ₂ O contained in the Cu ₂ O slurry to Cu to grow Cu powder on the Pd particles. Characterized in that.

Description

METHOD OF MANUFACTURING MICRO COPPER POWDER FOR ELECTRONIC MATERIAL Easily controlled by particle size {METHOD OF MANUFACTURING FINE CUPPER POWDERS FOR ELECTRONIC MATERIALS WITH EASILY SIZE CONTROL}

The present invention relates to a method for producing fine copper powder, and more particularly, to a method for producing fine copper powder for an electronic material, the particle size of which is easy to control.

With the rapid development of the electronics industry, electronic circuit devices are becoming smaller, more functionalized, diversified and precise. Advanced electronics demand materials with excellent properties and functionality. In particular, the amount of copper powder is rapidly increasing in accordance with miniaturization and multifunction of electronic products, and copper powder in micron (μm) units is widely used as a conductive ink, a paste, and a contact material for semiconductor devices.

In general, copper powder is prepared by a liquid reduction method that is synthesized by reducing in an aqueous solution or an organic solution to obtain a high purity metal.

However, the production of fine copper powder using the conventional liquid phase reduction method requires a high process cost, and the process conditions are difficult.

In addition, the copper powder produced by using the conventional liquid reduction method has a problem that the oxide film is formed on the surface, the electrical properties of the copper powder to be produced is reduced.

An object of the present invention is to provide a method for producing a fine copper powder for electronic materials having a fine particle size and even particle size distribution to be applied to the production of high-density electronic circuit devices.

Method for producing a fine copper powder for an electronic material according to an embodiment of the present invention for achieving the above object comprises the steps of (a) preparing a Pd suspension containing palladium (Pd) particles as a seed (seed); (b) adding Cu ₂ O to the Pd suspension to form a Cu ₂ O slurry having a concentration of Cu ₂ O of 1.25-40 g / L; And (c) supplying N ₂ H ₄ to the Cu ₂ O slurry as a reducing agent to reduce Cu ₂ O contained in the Cu ₂ O slurry to Cu to grow Cu powder on the Pd particles. Characterized in that.

In the method for producing fine copper powder for an electronic material according to the present invention, by growing a copper powder on a palladium seed by using a N ₂ H ₄ reducing agent using a Cu ₂ O slurry with optimized Cu ₂ O concentration, the average particle size is 0.1 ~ A fine copper powder of 1.0 μm can be easily produced. In addition, in the Cu ₂ O slurry, the particle size control can be facilitated by adjusting the concentration of Cu ₂ O.

1 is a flow chart schematically showing a method for producing fine copper powder for an electronic material according to the present invention.
2 to 8 show SEM results of the prepared copper powder according to the Cu ₂ O concentration.
9 shows the reaction time according to the Cu ₂ O concentration.
10 shows the content of Pd activated in the reaction by measuring the concentration of Pd participating in the reaction according to the concentration of Cu ₂ O.
Figure 11 shows the average particle size distribution of the copper powder prepared according to the Cu ₂ O concentration change.
Figure 12 shows the X-ray diffraction pattern of the reaction product with the reaction time.
13 to 17 show SEM results of the copper powder produced by changing the reaction temperature to 40 ~ 80 ℃.
18 shows particle size and time taken for the reaction according to the reaction temperature.
Figure 19 shows the change in particle size distribution with the reaction temperature.
20 shows the concentration of Pd activated in the reaction by measuring the concentration of Pd participating in the actual reaction according to the reaction temperature.

BRIEF DESCRIPTION OF THE DRAWINGS The advantages and features of the present invention, and how to accomplish them, will become apparent with reference to the embodiments and drawings described in detail below.

However, it is to be understood that the present invention is not limited to the disclosed embodiments, but may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. It is intended that the disclosure of the present invention be limited only by the terms of the appended claims.

Hereinafter, a fine copper powder manufacturing method for an electronic material having an easy particle size control according to the present invention will be described in detail.

1 is a flow chart schematically showing a method for producing fine copper powder for an electronic material according to the present invention.

Referring to FIG. 1, the method for preparing fine copper powder according to the present invention includes preparing a Pd suspension (S110), forming a Cu ₂ O slurry (S120), and reducing a Cu ₂ O using N ₂ H ₄ step (S130). .

Raise Pd Suspension

In the preparing of the Pd suspension (S110), a Pd suspension containing palladium (Pd) particles as a copper powder generating seed is prepared.

Pd particles act as a nucleus for the production and growth of copper powder. Silver (Ag) can also be used as a seed at the time of copper powder formation. However, in the case of silver, the phenomenon of substituting copper occurs. This is a problem that the copper fine glass particles are produced rather than growing the copper in powder form to produce a uniform particle having a dense surface.

However, in the case of palladium (Pd), the surface activity is better than silver, and copper particles are formed on the surface of the palladium according to the catalytic reaction, thereby easily growing into larger particles, thereby producing particles and particles having a dense surface.

In this case, the palladium particles may be obtained by dissolving PdCl ₂ in distilled water and ionizing the same, and then adding N ₂ H ₄ as a reducing agent through a chemical reaction according to Schemes 1 and 2 below.

Scheme _{1: N 2 H 4 + 4OH} - → N 2 + 4H 2 O + 4e -

Scheme ^{2: Pd +2 + 2e - →} Pd

Since the higher the concentration of palladium ions, the more nuclei in which the copper powder can be generated, the copper powder generation time by the reduction reaction of Cu ₂ O can be shortened, and the particle size distribution of the generated copper powder Can be reduced and the size of the powder can be reduced. However, when the concentration of palladium ions exceeds 1 x 10 ^-4 M, the amount of copper precipitated in the palladium seed in the reduction reaction of Cu ₂ O is too small, there is an uneconomical problem.

Therefore, the concentration of palladium ions (Pd ²⁺ ) dissolved in distilled water is preferably 1 × 10 ⁻⁶ M to 1 × 10 ⁻⁴ M.

Meanwhile, the palladium suspension may include polyvinyl pyrrolidone (PVP) as a stabilizer. At this time, the concentration of PVP is preferably 5 g / L ~ 15 g / L. If the PVP has a concentration of less than 5 g / L, it is difficult to obtain a sufficient stabilization effect of palladium. On the contrary, when the concentration of PVP exceeds 15 g / L, the particles have irregular phenomena due to the excessive dispersion effect, making it difficult to control the particle size.

Cu ₂ O slurry formation

In the Cu ₂ O slurry forming step (S120), Cu ₂ O is added to the palladium suspension to form a Cu ₂ O slurry.

In order to improve the dispersibility of the palladium particles or copper powder, sodium pyrophosphate (Na ₄ O ₇ P ₂ ) may be added to the Cu ₂ O slurry as a dispersant. The sodium pyrophosphate may be supplied in the form of a hydrate such as Na ₄ O ₇ P _{2 ·} 10H ₂ O. At this time, the sodium pyrophosphate is preferably added at a concentration of 80 mg / L ~ 120 mg / L. If the concentration of sodium pyrophosphate is less than 80 mg / L, the dispersion effect of palladium seed or copper powder is insufficient. In addition, when the concentration of sodium pyrophosphate exceeds 120 mg / L may lead to a reduction in the purity of the copper powder prepared without further dispersing effect.

On the other hand, the concentration of Cu ₂ O in the Cu ₂ O slurry is preferably 1.25 ~ 40 g / L. When the concentration of Cu ₂ O is less than 1.25 g / L, the amount of Cu powder deposited on the activated palladium seed is low, which is uneconomical. On the contrary, when the concentration of Cu ₂ O exceeds 40 g / L, the particle size distribution is excessively widened, and the average particle size of the copper powder to be produced is also excessively increased.

N ₂ H ₄  Use Cu ₂ O reduction

The Cu ₂ O reduction step (S130) with N ₂ H ₄ by reduction of Cu ₂ O in the Cu ₂ O slurry of Cu, to form a copper powder to the palladium particles. At this time, N ₂ H ₄ is used as the reducing agent. The reducing agent N ₂ H ₄ in this step (S130) may be supplied in the form of hydrazine monohydrate (N ₂ H _{4 ·} H ₂ O), it can be applied in the palladium suspension preparation step (S110) as well.

The reducing agent N ₂ H ₄ is preferably supplied in a semi-continuous manner using a dropwise method of dropwise dropping the reaction vessel in the form of hydrazine monohydrate. As a result of the experiment, the monodisperse copper powder could be secured and the particle size was easy to control when supplying dropwise semi-continuously during the reaction than the batch method of supplying hydrazine monohydrate at once.

On the other hand, when the injection rate of the hydrazine monohydrate is less than 0.3 mL / min, the size of the copper powder produced is large, there was a problem that the dispersibility is lowered. As the injection rate of hydrazine monohydrate increases, the size of the copper powder produced decreases, and the dispersibility is improved. However, since the effect of the injection rate of hydrazine monohydrate is included at 10 mL / min, it is preferable that the injection rate of N ₂ H ₄ is 0.3 ~ 10 mL / min.

The copper powder may be obtained through a chemical reaction according to Schemes 3 to 5 below.

Scheme _{3: N 2 H 4 + 4H} 2 O + 2e - → 2NH 4 OH + 2OH -

Scheme 4: Cu ₂ O + ₄ NH ₄ OH → 2 [Cu (NH ₃ ) ₂ ] ⁺ + 4 H ₂ O + 1 / 2O ₂

Scheme 5 _{: [Cu (NH 3) 2} ] + + e - + 2H 2 O → Cu + 2NH 4 OH

Scheme 4 corresponds to a process in which copper is dissolved in Cu ₂ O to form a copper ammonium complex, and Scheme 5 corresponds to a process in which the copper ammonium complex is reduced by electrons and grown on a palladium seed.

In the present invention, the reduction reaction of Cu ₂ O for producing copper powder is preferably carried out at a temperature of 50 ℃ to 80 ℃. If the reaction temperature is less than 50 ℃ there is a problem that the reaction does not occur, on the contrary, if the reaction temperature exceeds 80 ℃ there is a problem that it is difficult to produce a powder having a constant particle size by increasing the particle size of the powder.

In addition, in the present invention, the reduction reaction of Cu ₂ O for the production of copper powder is preferably carried out for at least 5 minutes, referring to Figure 12, etc., more preferably about 5 to 50 minutes in consideration of other conditions. desirable. If the reaction time is less than 5 minutes, the liquid phase reduction of Cu ₂ O is insufficient, and the amount of Cu ₂ O to Cu change may be insufficient.

The copper powder prepared according to FIG. 1 may have a spherical shape, and may have an average particle size of 0.1 μm to 1.0 μm.

Example

Hereinafter, a method of manufacturing fine copper powder for an electronic material according to the present invention will be described through a preferred embodiment of the present invention. It is to be understood, however, that the same is by way of illustration and example only and is not to be construed in a limiting sense.

Details that are not described herein will be omitted since those skilled in the art can sufficiently infer technically.

The materials used in the examples are as follows.

Copper source: Copper (I) oxide (Cu ₂ O, purity 95%, Junsei chemical Co., Japan

Palladium (Pd): PdCl ₂ (purity 99.99%, Kojima chemical reagents Inc., Japan.) Dissolved in distilled water and used.

Reducing Agent: N ₂ H ₄ .H ₂ O, Purity 80%, DC chemical Co., Korea)

Stabilizer: PVP k-30 (C ₆ H ₆ NO) _n 12 ~ 13%, Junsei Chemical Co., Japan

Dispersant: Na ₄ O ₇ P _{2 ·} 10H ₂ O 99%, Junsei Chemical Co., Japan

All the reagents were dissolved in deionized water and used in the experiment. After the synthesis of Cu powder, washing was performed three times using deionized water and ethanol to investigate their properties.

Cu ₂ O and Cu (OH) ₂ Distilled water solubility and surface area

Table 1 shows the solubility and surface area of distilled water of Cu ₂ O and Cu (OH) ₂ .

[Table 1]

Referring to Table 1, it can be seen that the solubility of distilled water of Cu ₂ O and Cu (OH) ₂ is very low compared to CuSO ₄ . Through this, it can be inferred that when the copper powder is prepared using the copper oxide slurry, since the solubility of the copper ions dissolved is small, it is possible to prevent aggregation of the copper powder and increase monodispersion during the reaction.

However, referring to Table 1, it can be seen that the specific surface area of Cu (OH) ₂ is 10 times or more larger than that of Cu ₂ O. In the case of Cu (OH) ₂ , the specific surface area of the metal powder is increased to increase the amount of dissolved ions. Therefore, in order to lower the solubility of the copper ions, it is more preferable to use a Cu ₂ O.

Cu ₂ Effect of O Concentration

2 to 8 show SEM results of the prepared copper powder according to the Cu ₂ O concentration, and FIG. 9 shows the reaction time according to the Cu ₂ O concentration.

Experiments Pd ²⁺ concentration 11.5x10 ^-6 M, temperature 60 ℃, PVP concentration of _{10 g / L, N 2 H} 4 0.6 mL / min and _{Na 4 O 7 P 2 Cu 2} O concentration from the experimental conditions of 99 mg / L The SEM results and particle size and reaction time of the copper powder prepared while varying from 2.5 to 40 g / L were measured.

2 to 8, it can be seen that the shape of the copper powder produced under the overall reaction conditions is spherical and relatively dispersed. However, as the concentration of Cu ₂ O increases from 1.25 g / L to 2.5 g / L, the average particle size decreases from 183 nm to 178 nm, but the particle size increases from 2.5 g / L to 40 g / L. Increases to 354 nm. This seems to be due to an increase in the concentration of copper ammonium complexes, which are precursors of copper.

Referring to FIG. 9, as the Cu ₂ O concentration changes, the particle size gradually decreases initially and then continuously increases, but the reaction time is slowed after the initial increase slightly. This is because, as the concentration of Cu ₂ O increases, the solubility of Cu participating in the reaction increases, and the amount of precipitation of the activated Pd increases.

10 shows the content of Pd activated in the reaction by measuring the concentration of Pd participating in the reaction according to the concentration of Cu ₂ O.

10, the content of the active Pd appears the 14% Pd content, if the concentration of 1.25 g / L of Cu ₂ O and the Cu ₂ O concentration of 2.5, 5, 10, 20, 30 and 40 g / L It can be seen that the activated Pd content changes to 28, 47, 55, 72, 81 and 86% when changed.

That is, it can be seen that the content of activated Pd increases rapidly until the Cu ₂ O concentration is 10 g / L, but the rate of increase slows down thereafter. As the concentration of dissolved Cu increases, the initial Cu ₂ O concentration precipitates in activated Pd, and the average particle size decreases. However, as the concentration of Cu ₂ O increases, the particle size distribution appears to be unstable due to insufficient activated Pd.

Figure 11 shows the average particle size distribution of the copper powder prepared according to the Cu ₂ O change.

Referring to FIG. 11, as the concentration of Cu ₂ O increases, the particle size distribution is narrowed, and the particle size distribution is widened at 40 g / L. This is because non-uniformity of particle growth and particle size appears as the solubility of Cu increases.

Influence of reaction time

Figure 12 shows the X-ray diffraction pattern of the reaction product with the reaction time.

Experimental conditions were Pd ⁺² 57.5x10 ^-6 M, PVP 10 g / L, Cu ₂ O 10g / L, reaction temperature 60 ° C, N ₂ H ₄ 0.6 ml / min, Na ₄ O ₇ P ₂ 99 mg / L , XRD results of the reaction product after 0 minutes, 5 minutes, 10 minutes and 20 minutes.

Referring to FIG. 12, it can be seen that a peak of Cu ₂ O is visible until 10 minutes of reaction time, but only a crystal phase of Cu is present after 20 minutes. The XRD results show that only Cu ₂ O and Cu peaks are seen throughout the reaction time, indicating that Cu ₂ O is directly converted to Cu in this reaction. In spite of the low solubility of Cu ₂ O, it can be seen that the Cu powder formation reaction is converted to the normal crystal growth phases of dissolution, reduction, nucleation and nucleation.

Influence of reaction temperature

The effect of reaction temperature for preparing Cu powder from Cu ₂ O slurry was investigated. For the experiment, Pd ²⁺ concentration 11.5 × 10 ⁻⁶ M, PVP concentration 10 g / L, Cu ₂ O concentration 10 g / L, N ₂ H ₄ 0.6 mL / min and Na ₄ O ₇ P ₂ 99 mg / L Using experimental conditions, the reaction temperature was changed to 40-80 ° C.

13 to 17 show SEM results of the copper powder produced by changing the reaction temperature to 40 ~ 80 ℃.

13 to 17, it can be seen that as the reaction temperature increases, the shape of the particles becomes spherical, the dispersion degree also increases, and the particle size decreases.

18 shows particle size and time taken for the reaction according to the reaction temperature.

Referring to FIG. 18, as the reaction temperature increases from 40 ° C. to 80 ° C., the average particle size of the reaction product appears to decrease from 425 nm to 150 nm. It can be seen that the particle size decreases linearly at the overall reaction temperature and the rate of decrease decreases above 50 ° C.

In addition, referring to Figure 18, it can be seen that the time required to complete the reaction is also decreasing linearly with increasing temperature. This seems to be because the amount of Cu dissolved from Cu ₂ O increases with increasing temperature, and the dissolved Cu rapidly precipitates in the seed Pd.

Figure 19 shows the change in particle size distribution with the reaction temperature.

Referring to FIG. 19, it can be seen that the particle size distribution changes from bi-modal to mono-modal as the temperature increases. It can be seen that as the reaction temperature increases, the degree of activation of Pd, which acts as a seed, increases and, accordingly, the particle size distribution narrows to mono-modal.

20 shows the concentration of Pd activated in the reaction by measuring the concentration of Pd participating in the actual reaction according to the reaction temperature.

Referring to FIG. 20, it can be seen that the concentration of activated Pd also increases as the reaction temperature increases. In other words, as the amount of Pd participating in the reaction increases, the particle size decreases and the particle size distribution changes to mono-modal.

While the present invention has been described in connection with what is presently considered to be practical 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 the present invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. It is therefore to be understood that the above-described embodiments are illustrative in all aspects and not restrictive.

S110: preparing the palladium suspension
S120: Cu ₂ O slurry formation step
S130: Cu ₂ O reduction step using N ₂ H ₄

Claims (10)

(a) preparing a Pd suspension containing palladium (Pd) particles as a seed;
(b) adding Cu ₂ O to the Pd suspension to form a Cu ₂ O slurry having a concentration of Cu ₂ O of 1.25-40 g / L; And
(c) supplying N ₂ H ₄ to the Cu ₂ O slurry as a reducing agent to reduce Cu ₂ O contained in the Cu ₂ O slurry to Cu to grow Cu powder on the Pd particles; and ,
(c) supplying N ₂ H ₄ to the Cu ₂ O slurry as a reducing agent to reduce Cu ₂ O contained in the Cu ₂ O slurry to Cu to grow Cu powder on the Pd particles; and ,
The N ₂ H ₄ is a fine copper powder manufacturing method for an electronic material, characterized in that supplied in a rate of 0.3 ~ 10 mL / min semi-continuously using a dropwise (dropwise) method.
The method of claim 1,
N ₂ H ₄ is
Method for producing a fine copper powder for electronic materials, characterized in that supplied in the form of hydrazine monohydrate (Hydrazine monohydrate).
delete delete The method of claim 1,
The palladium suspension is
PdCl ₂ is dissolved in distilled water and ionized, and then N ₂ H ₄ is added to obtain a fine copper powder for an electronic material, characterized in that obtained through the chemical reaction according to Schemes 1 and 2.
Scheme _{1: N 2 H 4 + 4OH} - → N 2 + 4H 2 O + 4e -
Scheme ^{2: Pd +2 + 2e - →} Pd
The method of claim 5,
The copper powder is
Method for producing a fine copper powder for an electronic material, characterized in that obtained through the reaction according to Schemes 3 to 5.
Scheme _{3: N 2 H 4 + 4H} 2 O + 2e - → 2NH 4 OH + 2OH -
Scheme 4: Cu ₂ O + ₄ NH ₄ OH → 2 [Cu (NH ₃ ) ₂ ] ⁺ + 4 H ₂ O + 1 / 2O ₂
Scheme 5 _{: [Cu (NH 3) 2} ] + + e - + 2H 2 O → Cu + 2NH 4 OH
The method of claim 5,
The concentration of palladium ions (Pd ²⁺ ) dissolved in the distilled water is
1 x 10 ^-6 M to 1 x 10 ^-4 M, characterized in that the fine copper powder manufacturing method for electronic materials.
The method of claim 1,
The palladium suspension
Polyvinyl pyrrolidone (PVP) is a method for producing fine copper powder for electronic materials, characterized in that added at a concentration of 50 ~ 150 g / L.
The method of claim 1,
The Cu ₂ O slurry
Method for producing fine copper powder for electronic materials, characterized in that sodium pyrophosphate is added at a concentration of 80 ~ 120 mg / L.
The method of claim 1,
The step (c)
Method for producing fine copper powder for electronic materials, characterized in that carried out at a temperature of 50 ℃ to 80 ℃.

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