WO2008059789A1 - Silver-plated fine copper powder, conductive paste produced from silver-plated fine copper powder, and process for producing silver-plated fine copper powder - Google Patents

Abstract

A process for producing a silver-plated fine copper powder characterized by treating a fine copper powder with an alkaline solution to remove organic substances present on the surface of the fine copper powder, washing the powder with water, washing an oxide present on the surface of the fine copper powder with an acidic solution, washing the powder with water, subsequently adding a reducing agent to an acidic solution containing this fine copper powder dispersed therein to produce a slurry of the fine copper powder, regulating the pH of the slurry, and then continuously adding to this fine-copper-powder slurry a solution of silver ions complexed with a chelating agent to thereby form a silver layer on the surface of the fine copper powder by electroless displacement plating and reductive plating. This process eliminates problems in conventional silver-plated fine copper powders, e.g., that the fine copper powders obtained through silver plating reaction differ in color tone according to the oxidized state thereof before silver plating and that the silver plating causes a decrease in tap density. The silver-plated fine copper powder is excellent in electrical conductivity and reproducibility in silver plating reaction and has almost the same tap density as the raw fine copper powder.

Description

 Specification

 Silver-plated copper fine powder, conductive paste produced using silver-plated copper fine powder, and method for producing silver-plated copper fine powder

 Technical field

 [0001] The present invention relates to a silver-plated copper fine powder, a conductive paste produced using the silver-plated copper fine powder, and a method for producing the silver-plated copper fine powder, and is particularly excellent in conductivity and reproducibility during the silver-plated reaction. The present invention relates to a silver-plated copper fine powder having a tap density comparable to that of the raw material copper fine powder.

 Background art

 Conventionally, copper fine powder has been widely used as a raw material for conductive paste. Conductive pastes are widely used from experimental purposes to applications in the electronics industry because of their ease of contact.

 In particular, silver-plated copper fine powder with a silver layer coated on its surface is processed into a conductive paste and applied to circuit formation of printed wiring boards using a screen printing method, various electrical contact portions, etc. It has been used as a material for ensuring electrical continuity.

 This is because the silver-plated copper fine powder is more excellent in electrical conductivity than the copper fine powder when compared with normal copper fine powder that does not cover the surface with a silver layer. In addition, silver powder alone is expensive, but if silver is attached to copper, the conductive powder as a whole will be inexpensive and the production cost can be greatly reduced. Therefore, a conductive paste made of fine copper powder coated with silver, which is superior in conductive properties, has a great advantage if a low-resistance conductor can be manufactured at low cost.

 [0004] By the way, a technique for producing such a silver-plated copper fine powder for a conductive paste is generally known by an electroless substitution plating method using a substitution reaction between copper and silver. Patent Document 1 describes a method of substituting and depositing silver on the surface of metallic copper powder using a silver complex solution of silver nitrate, ammonium carbonate, and ethylenediamine tetraacetate.

Patent Document 2 discloses a method in which copper powder is dispersed in a chelating agent solution, a silver nitrate solution is added to the copper powder dispersion, a reducing agent is added in the next step, and a silver film is deposited on the surface of the copper powder. Is disclosed. Furthermore, in Patent Document 3, a chelating agent is added to a copper powder dispersion to prepare a copper powder slurry, and a buffer is added thereto to adjust pH, and then silver ions are added to this for a substitution reaction. A technique for making silver-coated copper powder is disclosed.

[0005] The silver-plated copper fine powder obtained by these production methods is excellent in electrical conductivity and moisture resistance, and has been used as a suitable material as a conductive paste material. However, the silver-plated copper fine powders obtained by these manufacturing methods have variations in the color tone after the silver-plated reaction due to the oxidation state of the copper fine powder before the silver-plated, and the tap density is reduced by the silver-plated, etc. I had a problem.

 Patent Document 1: JP-A-57-59283

 Patent Document 2: JP-A-2-46641

 Patent Document 2: JP 2004-52044 A

 Disclosure of the invention

 Problems to be solved by the invention

[0006] The present invention aims to solve the above-described problems, and is a silver-plated copper fine powder having excellent conductivity and reproducibility during a silver-plated reaction, and having a tap density similar to that of the raw copper fine powder, and a method for producing the same. Provide law.

 Means for solving the problem

[0007] As a result of diligent research to solve the above problems, the present inventors have introduced a surface treatment step before and after the silver plating reaction in the conventional silver plating copper fine powder, and electroless substitution plating and reduction type. By forming a silver layer on the surface of the copper fine powder by plating, it was found that the silver-plated copper fine powder was excellent in reproducibility during the production of silver plating and had a tap density similar to that of the raw copper powder.

 [0008] Based on these findings, the present invention

1) Silver-plated copper fine powder with average particle size;! ~ 30 111, tap density 2.4 g / cm ³ or more, specific surface area 0.9 m ² / g or less

2) Silver-plated copper fine powder with an average particle size of 3 to 20 111, tap density of 3. Og / cm ³ or more, and specific surface area of 0.6 mg or less

3) The above 1 or 2 above, wherein the silver-plated copper fine powder is further coated with 0.0%;! To 5.0% by weight of fatty acid. Is the silver-plated copper fine powder described in 2.

 4) The silver-plated copper fine powder according to 1 or 2 above, wherein the silver-plated copper fine powder is further coated with 0.;!-1.0% by weight of fatty acid.

 5) Provided is a conductive paste produced using the silver-plated copper fine powder according to any one of 1 to 4 above.

 The present invention also provides

 6) In the silver-plated copper fine powder manufacturing method that forms a silver layer on the surface of the copper fine powder, remove the copper fine powder from the organic matter on the surface of the copper fine powder in an alkaline solution. After pickling and washing the product, a reducing agent is added to the acidic solution in which the copper fine powder is dispersed to adjust the pH to create a copper fine powder slurry, and a silver ion solution is continuously added to the copper fine powder slurry. A method for producing silver-plated copper fine powder in which a silver layer is formed on the surface of the copper fine powder by electroless replacement plating and reduced electroless plating.

 7) The method for producing silver-plated copper fine powder according to 6 above, wherein potassium hydroxide is used as the alkaline solution and sulfuric acid is used as the acidic solution.

 8) The method for producing a silver-plated copper fine powder according to 6 or 7 above, wherein one or more selected from polyvalent carboxylic acids or salts thereof or formaldehyde are used as the reducing agent

 9) The method for producing a silver-plated copper fine powder according to any one of the above 6 to 8, wherein the pH at the start of addition of the silver ion solution is adjusted to 3.0 to 5.0

 10) The method for producing a silver-plated copper fine powder according to any one of 6 to 8 above, wherein the pH at the start of addition of the silver ion solution is adjusted to 3.5 to 4.5.

 11) The method for producing a silver-plated copper fine powder according to any one of 6 to 10 above, wherein the silver ion solution is a transparent ammoniacal silver nitrate solution.

 12) The silver-plated copper fine powder according to any one of 6 to 11 above, wherein the silver-plated copper fine powder is heat-treated in a reducing atmosphere under a hydrogen stream at 150 to 220 ° C. for 20 to 90 minutes. Production method

13) The silver-plated copper fine powder according to any one of 6 to 11 above, wherein the silver-plated copper fine powder is heat-treated in a reducing atmosphere under a hydrogen stream at 180 to 210 ° C. for 20 to 40 minutes. Production method

14) The silver plating copper fine powder is immersed in an alcohol solution containing a fatty acid, and the surface of the silver plating copper fine powder is coated with 0.01 to 5.0 wt% of fatty acid. Silver Method for producing fine copper powder

 15) The silver plating copper fine powder is immersed in an alcohol solution containing a fatty acid, and the surface of the silver plating copper fine powder is coated with 0.;! To 1.0% by weight of fatty acid. A method for producing a silver-plated copper fine powder.

 The invention's effect

 [0010] The surface of the copper fine powder is uniformly coated by introducing a surface treatment step before and after the silver plating reaction and forming a silver layer on the surface of the copper fine powder by electroless substitution plating and reduction type plating. As a result, it has excellent conductivity and reproducibility at the time of silver plating reaction, resulting in silver plating copper fine powder with tap density comparable to that of raw copper fine powder, which is stable when used in conductive paste. In addition, it has an excellent effect that high filling can be achieved.

 BEST MODE FOR CARRYING OUT THE INVENTION

[0011] Conventionally, since an alkaline solution is used instead of an acidic solution, the copper hydroxide may be re-precipitated when taken out as a powder. In addition, since the silver ion solution was charged all together during the substitution reaction, it was considered that the silver ion concentration became non-uniform around the copper powder, and silver-plated copper fine powder with poor silver coating was formed.

 In contrast, the present invention removes the organic matter on the surface of the copper fine powder by dispersing the copper fine powder in the alkaline solution, and removes the oxide on the surface of the copper fine powder by dispersing the copper fine powder in the acidic solution. The pH is adjusted so that the copper ions complexed by the agent can be maintained in a stable state, and the silver ion solution is continuously added so that the substitution reaction with silver ions proceeds uniformly. The silver layer can be coated extremely uniformly on the surface of the copper fine powder.

[0012] Sodium hydroxide, potassium hydroxide, or the like is used as the alkaline solution. An alkaline solution that can reliably remove the organic matter on the surface of the copper fine powder before the substitution reaction is preferred, but potassium hydroxide is preferred.

In an acidic solution, sulfuric acid, hydrochloric acid, phosphoric acid or the like is used. It is preferable to use sulfuric acid, and it should be an acidic solution that can reliably remove the copper oxide on the surface of the copper fine powder before the substitution reaction. The selected type and concentration should not excessively dissolve the copper fine copper itself. there is a need force ^s to. The pH of this acidic solution is preferably in the acidic range of 2 · 0 to 5 · 0. When ρΗ exceeds 5.0, oxides of copper fine powder cannot be sufficiently dissolved and removed, and when pH is lower than 2.0, copper powder dissolves and the copper fine powder itself tends to aggregate. More preferably, it is an acidic region of ρΗ3.5 to 4.5.

 [0013] In the production method of the present invention, the chelating agent can use EDTA, ammonia, or the like. The chelating agent used in the present invention is not particularly limited as long as the effects of the present invention are exhibited, but is preferably ammonia.

Addition of ammonia water to silver nitrate solution causes precipitation, but addition of excess ammonia water gives a clear ammoniacal silver nitrate solution (with [Ag (NH)] ⁺ in it)

 3 2

 . When a reducing agent such as sodium potassium tartrate is added thereto, silver is deposited on the surface of the copper fine powder, and silver-plated copper fine powder is formed.

 [0014] In the present invention, polycarboxylic acid, polyvalent carboxylates, formaldehyde and the like can be used as the reducing agent. For example, sodium potassium tartrate (Rosiel salt) and glucose (glucose). Preferably, it is sodium potassium tartrate (Roschel's salt), and this reducing agent exhibits weak reducing power and reduces only the oxides (CuO, Cu 0, AgO, Ag O) that are produced as a by-product of the substitution reaction. The complex ion of

 twenty two

 Yes

 [0015] A silver nitrate solution is used as the silver ion solution in the present invention. The silver ion solution used in the present invention is not particularly limited as long as the effects of the present invention are exhibited. The silver nitrate solution has a silver nitrate concentration of 20 to 300 g / L, preferably 50 to 100 g / L.

 The rate of the silver ion solution added to the copper fine powder slurry is 200 mL / min or less, preferably lOOmL / min or less. By adding a silver nitrate solution in the above concentration range at a relatively slow rate, practically 20 to 200 mL / min, a uniform silver layer can be reliably coated on the copper fine powder surface.

[0016] Further, in the production method of the present invention, it is preferable to carry out a decantation treatment after the copper fine powder is dispersed in the acidic solution. Decantation treatment is also called the gradient method. After copper fine powder is dispersed in an acidic solution, the solution is allowed to stand to settle copper fine powder or silver-plated copper fine powder, and then the supernatant is gently tilted. Operation to separate and collect. This In this case, since the copper fine powder or silver-plated copper fine powder does not come into contact with the atmosphere, it is possible to proceed to the next step in a state in which re-oxidation of the copper fine powder or silver-plated copper fine powder is prevented.

 [0017] One method of post-treatment used in the production method of the present invention is 150 to 220 in a reducing atmosphere under a hydrogen stream. C, heat treatment for 30-90 minutes. Preferably 180-210. C, heat treatment is carried out for 20 to 40 minutes, and by this heat treatment, the interface between the copper fine powder and the silver layer is partially alloyed, so that the bond strength at the interface can be increased.

 The silver-plated copper fine powder is kneaded with a resin or solvent when it is made into a conductive paste. However, if the bonding force at the interface is weak, the silver layer will peel off when subjected to mechanical friction. Therefore, heat treatment at a low temperature in a short time is effective. However, if heat treatment is carried out at a very high temperature or for a long time, silver may completely diffuse into copper.

 [0018] The second method of post-treatment used in the production method of the present invention is to immerse silver-plated copper fine powder in an alcohol solution containing 0.01 to 5.0% by weight of a fatty acid, and filter after stirring for about 30 minutes. , dry. Preferably, 0.;! ~ 1.0 Silver silver fine copper powder is immersed in an alcohol solution containing 10% by weight of fatty acid, filtered and dried after stirring for about 30 minutes. Stearic acid is used as the fatty acid. Fatty acid coating is achieved by the fact that the fatty acid is coated on the surface of the silver-plated copper fine powder to make the surface smooth, and that the fatty acid itself acts as a lubricant to increase the filling ability of the silver-plated copper fine powder. It has an excellent effect.

 These post-treatments can increase the tap density of the silver-plated copper fine powder, which has been lowered by the silver-plated reaction, to the same level as the raw copper powder, which is advantageous for via-hole applications that require high fillability.

 [0019] The silver-plated copper fine powder and the copper fine powder used in the production method shown above are obtained from ordinary electrolytic methods, reduction methods, atomization methods, mechanical pulverization, etc. with no particular restrictions on the type and production method. It is possible to use the copper fine powder that is used. Further, the shape of the copper powder may be a spherical shape, a flake shape, a needle shape, or a resin shape.

As described above, silver-plated copper fine powder having an average particle size of 1 to 30111, a tap density of 2.4 g / cm ³ or more, and a specific surface area of 0.9 m ² / g or less can be obtained. This silver-plated copper fine powder can further achieve an average particle size of 3 to 20 m, a tap density of 3. Og / cm ³ or more, and a specific surface area of 0.6 m ² / g or less. Further, the silver-plated copper fine powder can be made into a silver-plated copper fine powder having a structure covered with 0.01 to 5.0% by weight of fatty acid by the above treatment. Further, the silver-plated copper fine powder may have a structure coated with 0.;! To 1.0% by weight of fatty acid. These silver-plated copper fine powders are useful as conductive pastes. The present invention includes a conductive paste manufactured using these copper powders.

 Example

 Next, the present invention will be described based on examples. The following examples are for facilitating the understanding of the present invention, and the present invention is not limited by these examples. That is, modifications and other examples based on the technical idea of the present invention are included in the present invention.

 [Example 1]

 In Example 1,! /, V, electrolytic copper powder obtained by a method called a so-called electrolytic process was used, and copper fine powder obtained by further pulverizing with a jet mill was used. This copper fine powder had a weight cumulative particle size D of 6.2 111 as measured by a laser diffraction scattering particle size distribution measurement method.

 50

 500 g of this copper fine powder was added to 1000 ml of 1% aqueous potassium hydroxide solution and stirred for 20 minutes, followed by primary decantation treatment, and further 1000 ml of pure water was added and stirred for several minutes.

Yes

 Thereafter, secondary decantation treatment was performed, and 2500 ml of sulfuric acid aqueous solution having a sulfuric acid concentration of 15 g / L was added and stirred for 30 minutes. Further, tertiary decantation treatment was performed, 2500 ml of pure water was added, and the mixture was stirred for several minutes.

 Next, quaternary decantation treatment was performed, 2500 ml of a 1% sodium potassium tartrate solution was added and stirred for several minutes to form a copper slurry.

 A dilute sulfuric acid or potassium hydroxide solution was added to the copper slurry to adjust the pH of the copper slurry to 3.5 to 4.5.

[0022] To a copper slurry adjusted in pH, 1000 ml of a silver nitrate ammonia solution (a mixture of 887 · 5 g of silver nitrate and water added to adjust the water to 1000 ml) was slowly added over a period of 30 minutes. Substitution reaction treatment and reduction reaction treatment were performed, and stirring was further performed for 30 minutes to obtain a silver-plated copper fine powder. Thereafter, a fifth decantation treatment was performed, 3500 ml of pure water was added, and the mixture was stirred for several minutes. Further, a sixth decantation treatment was performed, 3500 ml of pure water was added, and the mixture was stirred for several minutes. Then, the silver-plated copper fine powder and the solution were separated by filtration and suction dehydration, and the silver-plated copper fine powder was dried at a temperature of 90 ° C. for 2 hours.

[0023] (Example 2)

 500 g of silver-plated copper fine powder prepared in Example 1 was dispersed in 750 ml of a 0.5% ethanolic stearate solution and stirred for 30 minutes. Then, the solution was separated from the stearic acid-coated silver-plated copper metal powder by filtration washing and suction dehydration, and the stearic acid-coated silver-plated copper metal powder was dried at a temperature of 90 ° C. for 2 hours.

[0024] (Example 3)

 500 g of the silver-plated copper fine powder prepared in Example 1 was placed in a tubular furnace and heat-treated at 200 ° C. for 30 minutes in a reducing atmosphere under a hydrogen stream (3.0 to 3.51 / min). The heat treated silver powdered copper fine powder was pulverized in a mortar.

[Example 4]

 500 g of silver-plated copper fine powder prepared in Example 3 was dispersed in 750 ml of 0.5% ethanol stearate solution and stirred for 30 minutes. Then, the solution was separated from the stearic acid-coated silver-plated copper metal powder by filtration washing and suction dehydration, and the stearic acid-coated silver-plated copper metal powder was dried at a temperature of 90 ° C. for 2 hours.

[Comparative Example 1]

 500 g of the copper fine powder used in Example 1 was added to 2500 ml of 1% sodium potassium tartrate solution and stirred for several minutes. Next, dilute sulfuric acid or potassium hydroxide solution was added to the copper slurry to adjust the pH of the copper slurry to 3.5-5.

 In this way, 1000 ml of silver nitrate ammonia solution (adjusted to 1000 ml of silver nitrate by adding 85.5 g of silver nitrate to water and adjusted to 1000 ml) was added to the copper slurry adjusted to ρΗ while slowly adding over 30 minutes. A reaction treatment and a reduction reaction treatment were performed, and stirring was further performed for 30 minutes to obtain a silver-plated copper fine powder.

Subsequently, decantation treatment was performed, 3500 ml of pure water was added, and the mixture was stirred for several minutes. After further decantation treatment, 3500 ml of pure water was added and stirred for several minutes. And filtration The silver-plated copper fine powder and the solution were separated by washing and dehydrating by suction, and the silver-plated copper fine powder was dried at a temperature of 90 ° C. for 2 hours.

[0027] The average particle size, specific surface area, apparent density, and tap density of the silver-plated copper fine powder according to the above-described examples were measured. The average particle size was determined by the laser diffraction scattering particle size distribution measurement method, and the value of weight cumulative particle size D was adopted. The specific surface area was measured by the BET method. Apparent

 50

 The density was measured according to JISZ2504. The tap density was measured according to JISZ2512. The results are shown in Table 1.

As shown in Table 1, the average particle diameter of the raw material powder 6.2 ^ 111, specific surface area 0. 48m ² / g, Tatsu flop density 4. 98 g / cm ^3, the resistivity is 2. 9 X 10_ ⁴ Ω became 'cm

In Example 1, an average particle diameter of 9.4 ^ 111, specific surface area 0. 33m ² / g, a tap density of 3. 92 g / cm ^3, the resistivity became ^{1 · 3X 10- 4 Ω 'cm} . In Example 2, an average particle diameter of 11. 7 m, specific surface area 0. 24m ² / g, a tap density of 4. 76 g / cm ^3, specific resistance 7. ivy Do and 1 X 10- ⁵ Ω 'cm. In Example 3, the average particle size is 13. 8Mie, specific surface area 0. 19 m ² / g, a tap density of 3. 99 g / cm ^3, the resistivity became ^{1. 1 X 10- 4 Ω 'cm} . In Example 4, the average particle size was 13.3 μm, the specific surface area was 0.16 m ² / g, the tap density was 4.95 g / cm ³ , and the specific resistance was 6.5 × 10−5 Ω′cm. .

All of these fall within the range of the silver-plated copper fine powder of the present invention having an average particle size of 1 to 30 111, a tap density of 2.4 g / cm ³ or more, and a specific surface area of 0.9 m ² / g or less. Thus, it was a suitable silver-plated copper fine powder. Moreover, none of the first through fourth embodiments, the specific resistance is 1 becomes less 5 X 10- ⁴ Ω 'cm, as compared with the comparative example of the raw material powder and below, and shows the good conductivity.

[0028] [Table 1] D ₅₀ Specific surface area Apparent density Yupp density Resistivity

(, μ m) (mVg) (g / cm ³ ) (g / cm ³ )

Raw material powder 6.2 0.48 3.69 4.98 2.9X10 " ⁴ Example 1 9.4 0.33 3.13 3.92

Example 2 11.7 0.24 3.93 4.76 7.1X10-5 Example 3 13.8 0.19 2.79 3.99 1.lXlO- ⁴ Example 4 13.3 0.16 4.34 4.95 6.5X10-5 Comparative Example 8.7 0.44 2.87 4.00

[0029] On the other hand, the average particle size of Comparative Example 1 is 8.7 m, the tap density is 4,000 gg / cm ^3, and the force specific surface area is 0.44 m ² / g, compared with the other examples. The silver-plated copper fine powder surface has many irregularities, the color tone of the silver-plated surface is poor, and the conductivity is lowered, so that the object of the present invention cannot be achieved, resulting in an undesirable result.

 Industrial applicability

[0030] The silver-plated copper fine powder in which the silver layer is uniformly coated on the surface of the copper fine powder according to the present invention has excellent conductivity.

 X X

 In addition, it has excellent reproducibility during silver plating reaction and has a tap density similar to that of the raw material copper fine powder, making it ideal for materials that ensure electrical continuity such as conductive paste.

Claims

The scope of the claims [I] Silver-plated copper fine powder characterized by having an average particle size of !! to 30 m, a tap density of 2.4 g / cm ³ or more, and a specific surface area of 0.9 mg or less. [2] A silver-plated copper fine powder characterized by having an average particle size of 3 to 20 Hm, a tap density of 3. Og / cm ³ or more, and a specific surface area of 0.6 mg or less.  [3] The silver-plated copper fine powder according to claim 1 or 2, wherein the silver-plated copper fine powder is further coated with 0.0;! To 5.0% by weight of a fatty acid.  [4] The silver-plated copper fine powder according to claim 1 or 2, wherein the silver-plated copper fine powder is further coated with 0.1 to 1.0% by weight of a fatty acid.  [5] A conductive paste produced using the silver-plated copper fine powder according to any one of claims 1 to 4.  [6] In the method of producing silver-plated copper fine powder that forms a silver layer on the surface of copper fine powder! /, Remove the copper fine powder surface organic matter in alkaline solution, wash with water and then acidify After pickling and washing the oxide on the surface of the copper fine powder in the solution, a reducing agent is added to the acidic solution in which the copper fine powder is dispersed to adjust the pH to prepare a copper fine powder slurry. A method for producing silver-plated copper fine powder, characterized in that a silver layer is formed on the surface of a copper fine powder by electroless substitution plating and reduced electroless plating by continuously adding a silver ion solution.  7. The method for producing fine silver-plated copper powder according to claim 6, wherein potassium hydroxide is used as the alkaline solution and sulfuric acid is used as the acidic solution.  [8] The method for producing fine silver-plated copper powder according to [6] or [7], wherein one or more selected from polyvalent carboxylic acids or salts thereof or formaldehyde is used as the reducing agent.  [9] The pH at the start of addition of the silver ion solution is adjusted to 3.0 to 5.0. The manufacturing method of the silver plating copper fine powder in any one of -8. [10] The pH at the beginning of the addition of the silver ion solution is adjusted to 3.5 to 4.5. The manufacturing method of the silver plating copper fine powder in any one of -8.  [I I] The method for producing fine silver-plated copper powder according to any one of claims 6 to 10, wherein the silver ion solution is a transparent ammoniacal silver nitrate solution. [12] Silver-plated copper fine powder in a reducing atmosphere under a hydrogen stream at 150 to 220 ° C for 20 to 90 minutes The method for producing silver-plated copper fine powder according to any one of claims 6 to 11, wherein heat treatment is performed.  [13] The silver plating according to any one of claims 6 to 11, wherein the silver plating copper fine powder is heat-treated in a reducing atmosphere under a hydrogen stream at 180 to 210 ° C for 20 to 40 minutes. A method for producing fine copper powder.  [14] The silver-plated copper fine powder is immersed in an alcohol solution containing a fatty acid, and the surface of the silver-plated copper fine powder is coated with 0.01 to 5.0% by weight of fatty acid. A method for producing a silver-plated copper fine powder according to any one of 13; [15] The silver-plated copper fine powder is immersed in an alcohol solution containing a fatty acid, and the surface of the silver-plated copper fine powder is coated with 0 · ;! to 1 · 0% by weight of fatty acid. The method for producing silver-plated copper fine powder according to any one of 13 to 13 above.