Preparation method of silver-coated copper powder

Abstract

The invention belongs to the technical field of metal powder, and particularly relates to a preparation method of silver-coated copper powder, which comprises the following steps: mixing copper salt, a dispersing agent, a reducing agent, an auxiliary agent and a solvent, reacting to obtain a copper solution, mixing silver salt, the dispersing agent, a complexing agent and the solvent to obtain a silver-ammonia solution, mixing the silver-ammonia solution and the copper solution, reacting to obtain the silver-coated copper powder, the preparation method of the silver-coated copper powder is simple, economical and reliable, the glutamic acid additive is added in the silver coating process, the conversion rate of a silver layer reaches up to 100%, and the prepared silver-coated copper powder is good in dispersity and high in compactness.

Description

Technical Field

[0001] The invention belongs to the technical field of metal powders, and in particular relates to a method for preparing silver-coated copper powder. Background Art

[0002] Silver-coated copper powder combines the high conductivity of copper powder with the good anti-oxidation properties of the silver coating, enabling the powder to improve the corrosion resistance and conductivity of the material while maintaining a low cost. Therefore, the application of silver-coated copper powder in the electronics industry has received increasing attention.

[0003] However, in the traditional preparation process of silver-coated copper powder, there are often problems such as uneven silver coating and insufficient adhesion. This is mainly due to the lack of sufficient electrostatic attraction between the copper powder surface and the silver particles, which causes the silver particles to be unable to stably adsorb on the copper powder surface or easily peel off, thus affecting the conductivity and stability of the material. Summary of the invention

[0004] The invention provides a method for preparing silver-coated copper powder. Glutamic acid is added during the silver coating process to form a negative charge layer on the surface of the copper powder, thereby enhancing the compactness of the silver-coated copper powder.

[0005] The technical solution of the present invention is as follows: A method for preparing silver-coated copper powder, comprising:

[0006] Step 1, mixing copper salt, dispersant, reducing agent and solvent evenly to react, and then adding auxiliary agent to obtain solution A;

[0007] Step 2, mixing the silver salt, the complexing agent, the dispersant and the solvent uniformly to obtain a solution B;

[0008] Step 3, adding solution B dropwise into solution A for reaction, filtering, washing with water, washing with alcohol, and drying to obtain silver-coated copper powder;

[0009] The auxiliary agent is glutamic acid.

[0010] As a preferred embodiment, the copper salt in step one is one or more of copper sulfate, copper nitrate, and copper chloride; the reducing agent in step one is one or more of sodium hypophosphite, ascorbic acid, glucose, and formaldehyde.

[0011] As a preferred embodiment, in the step 1, 700 to 1500 mL of solvent is added to every 300 g of copper salt; and in the step 1, the mass ratio of the dispersant to the copper salt is 0.05:1 to 0.15:1.

[0012] As a preferred embodiment, the mass ratio of the reducing agent to the copper salt in step one is 0.3:1 to 0.5:1; the mass ratio of the auxiliary agent to the copper salt in step one is 0.025:1 to 0.125:1.

[0013] As a preferred embodiment, the reaction temperature in step 1 is 80-120° C., and the reaction time is 1-3 hours.

[0014] As a preferred embodiment, the dispersant is one or more of alkylphenol polyoxyethylene ether, polyvinyl pyrrolidone, and sodium citrate; and the solvent is one or more of deionized water and distilled water.

[0015] As a preferred embodiment, the silver salt in step 2 is silver sulfate; the complexing agent in step 2 is one or more of disodium ethylenediaminetetraacetate, polyvinylpyrrolidone, ammonia water, and organic amines.

[0016] As a preferred embodiment, in the step 2, 400-600 mL of solvent is added to every 5 g of silver salt; the mass ratio of the complexing agent to the silver salt is 3:1-6:1; and the mass ratio of the dispersant to the silver salt is 0.5:1-3:1.

[0017] As a preferred embodiment, the dripping rate in step three is 6 to 10 mL / min, and the reaction time is 30 to 90 min.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] 1. By introducing glutamic acid to form a negative charge layer on the surface of copper powder, the electrostatic attraction between the copper powder surface and the silver layer can be significantly enhanced, thereby improving the uniformity and adhesion of the silver coating layer. This can not only improve the conductive properties of silver-coated copper powder, but also significantly improve its antioxidant properties and long-term stability.

[0020] 2. When copper powder is directly added during the preparation of silver-coated copper powder, the oxide layer and impurities on the surface of the copper powder will affect the coating effect, resulting in poor conductivity of the silver-coated copper powder. Dropping silver ammonia solution into the copper solution effectively solves this problem.

[0021] 3. The present invention uses deionized water or distilled water as solvent, which reduces the cost of large-scale production.

[0022] 4. The coordination effect between glutamic acid and silver ions can appropriately slow down the reduction process of silver ions. The reducing agent can destroy this coordination effect, release silver ions and reduce them to silver element. The combination of reducing agent and glutamic acid helps to form a more uniform silver coating.

[0023] 5. Glutamic acid is adsorbed on the metal surface, which can effectively prevent the agglomeration of particles. It works together with the dispersant to evenly distribute silver ions on the surface of copper powder, which helps to form stable and uniform silver-coated copper powder. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is a scanning electron microscope image of silver-coated copper powder. DETAILED DESCRIPTION

[0025] The preferred embodiments of the present invention are described in detail below in conjunction with the accompanying drawings so that the advantages and features of the present invention can be more easily understood by those skilled in the art, thereby making a clearer and more definite definition of the protection scope of the present invention.

[0026] Example 1

[0027] Prepare copper solution: weigh 200g copper sulfate and dissolve it in 800mL deionized water; add 12g PVP and 10g sodium citrate, stir for 30min, add 80g sodium hypophosphite, heat to 100℃, react for 2h, then cool to 30℃, add 5g glutamic acid, and stir for 3-4h.

[0028] Prepare silver stock solution: add 500mL of water, 5g of silver sulfate, 23g of ammonia water, 3g of ethylenediamine, 1g of PVP, and 3.5g of EDTA-2Na into a beaker, stir and mix for 30 minutes, then add the silver solution dropwise into the copper solution for 1 hour. After the addition is complete, react for 1 hour, pour the reaction product into a large beaker for sedimentation, and discard the supernatant. Stir and soak the lower layer of solid silver-coated copper powder with 40mL of deionized water for 10 minutes, and discard the supernatant after complete sedimentation. Repeat the operation twice. Stir and soak with 20mL of ethanol for 10 minutes, and discard the supernatant after complete sedimentation. Repeat the operation twice. After the third ethanol washing is completed, place the sample in a blast oven at 50°C for 6 hours. The dried sample is crushed and ground to obtain silver-coated copper powder. The scanning electron microscope image of the silver-coated copper powder is shown below Figure 1 shown.

[0029] Example 2

[0030] Prepare copper solution: weigh 200g copper sulfate and dissolve it in 800mL deionized water; add 12g OP-10, stir for 30min, add 80g sodium hypophosphite, heat to 100℃, react for 2h, then cool to 30℃, add 5g glutamic acid, and stir for 3-4h.

[0031] Prepare silver stock solution: add 500mL of water, 7g of silver sulfate, 23g of ammonia water, and 3.5g of EDTA-2Na to a beaker, stir and mix for 30min, then add the silver solution dropwise to the copper solution for 1h. After the addition is complete, react for 1h, pour the reaction product into a large beaker to settle, and pour out the supernatant. Stir and soak the lower layer of solid silver-coated copper powder with 40mL of deionized water for 10min, pour out the supernatant after sedimentation, and repeat the operation twice. Stir and soak with 20mL of ethanol for 10min, pour out the supernatant after sedimentation, and repeat the operation twice. After the third ethanol washing is completed, place the sample in a blast oven at 50℃ for 6h. Grind the dried sample to obtain silver-coated copper powder.

[0032] Example 3

[0033] Prepare copper solution: weigh 200g copper sulfate and dissolve it in 1000mL deionized water; add 12g PVP, stir for 60min, add 80g sodium hypophosphite, heat to 100℃, react for 2h, then cool to 30℃, add 6g glutamic acid, and stir for 3-4h.

[0034] Prepare silver stock solution: add 500mL of water, 5g of silver sulfate, 23g of ammonia water, 1g of PVP, 3g of ethylenediamine, and 3.5g of EDTA-2Na to a beaker, stir and mix for 30min, then add the silver solution dropwise to the copper solution for 1h. After the addition is complete, react for 1h, pour the reaction product into a large beaker for sedimentation, and pour out the supernatant. Stir and soak the lower layer of solid silver-coated copper powder with 40mL of deionized water for 10min, pour out the supernatant after sedimentation, and repeat the operation twice. Stir and soak with 20mL of ethanol for 10min, pour out the supernatant after sedimentation, and repeat the operation twice. After the third ethanol cleaning is completed, place the sample in a blast oven at 50℃ for 6h. Grind the dried sample to obtain silver-coated copper powder.

[0035] Comparative Example 1

[0036] Prepare copper solution: weigh 200g of copper sulfate and dissolve it in 800mL of deionized water; add 12g of PVP and 10g of sodium citrate, stir for 30min, add 80g of sodium hypophosphite, heat to 100℃, react for 2h, then cool to 30℃ and stir for 3-4h.

[0037] Prepare silver stock solution: add 500mL of water, 5g of silver sulfate, 23g of ammonia water, 3g of ethylenediamine, 1g of PVP, and 3.5g of EDTA-2Na to a beaker, stir and mix for 30min, then add the silver solution dropwise to the copper solution for 1h. After the addition is complete, react for 1h, pour the reaction product into a large beaker for sedimentation, and pour out the supernatant. Stir and soak the lower layer of solid silver-coated copper powder with 40mL of deionized water for 10min, pour out the supernatant after sedimentation is complete, and repeat the operation twice. Stir and soak with 20mL of ethanol for 10min, pour out the supernatant after sedimentation is complete, and repeat the operation twice. After the third ethanol washing is completed, place the sample in a blast oven at 50℃ for 6h. Grind and grind the dried sample to obtain silver-coated copper powder.

[0038] Comparative Example 2

[0039] Prepare copper solution: weigh 200 g of copper sulfate and dissolve it in 800 mL of deionized water; add 80 g of sodium hypophosphite, heat to 100°C, react for 2 hours, then cool to 30°C, add 5 g of glutamic acid, and stir for 3 to 4 hours.

[0040] Prepare silver stock solution: add 500mL of water, 5g of silver sulfate, 23g of ammonia water, 3g of ethylenediamine, 1g of PVP, and 3.5g of EDTA-2Na to a beaker, stir and mix for 30min, then add the silver solution dropwise to the copper solution for 1h. After the addition is complete, react for 1h, pour the reaction product into a large beaker for sedimentation, and pour out the supernatant. Stir and soak the lower layer of solid silver-coated copper powder with 40mL of deionized water for 10min, pour out the supernatant after sedimentation is complete, and repeat the operation twice. Stir and soak with 20mL of ethanol for 10min, pour out the supernatant after sedimentation is complete, and repeat the operation twice. After the third ethanol washing is completed, place the sample in a blast oven at 50℃ for 6h. Grind and grind the dried sample to obtain silver-coated copper powder.

[0041] The calculation formula of the yield is as follows, where m1 is the actual output mass of silver-clad copper, m2 is the theoretical mass of copper powder, and m3 is the theoretical mass of silver powder:

[0042]

[0043] The nano-tin powder was characterized and tested for morphology, as shown in Table 1, wherein the anti-oxidation resistance was measured after the prepared silver-coated copper powder was treated in a blast oven at 180° C. for 30 min.

[0044] Table 1

[0045]

[0046] Conclusion: The present invention discloses a method for preparing silver-coated copper powder. The process steps are simple and the process parameters are appropriate. The silver-coated copper powder is prepared in a water system with a yield of up to 98% and high dispersibility. The particle size distribution range measured by a laser particle size distribution instrument is 2 to 4 μm, the purity is high, and the powder can be applied to large-scale production with stable quality.

Claims

1. A method for preparing silver-coated copper powder, characterized in that: include: Step 1, mixing copper salt, dispersant, reducing agent and solvent evenly for reaction, and then adding auxiliary agent to obtain solution A; Step 2, mixing the silver salt, the complexing agent, the dispersant and the solvent to obtain a solution B; Step 3, adding solution B dropwise into solution A for reaction, filtering, washing with water, washing with alcohol, and drying to obtain silver-coated copper powder; The auxiliary agent is glutamic acid.

2. The method for preparing silver-coated copper powder according to claim 1, characterized in that: The copper salt in step 1 is one or more of copper sulfate, copper nitrate and copper chloride; the reducing agent in step 1 is one or more of sodium hypophosphite, ascorbic acid, glucose and formaldehyde.

3. The method for preparing silver-coated copper powder according to claim 1, characterized in that: In the step 1, 700 to 1500 mL of solvent is added to every 300 g of copper salt; in the step 1, the mass ratio of the dispersant to the copper salt is 0.05:1 to 0.15:

1.

4. The method for preparing silver-coated copper powder according to claim 1, characterized in that: The mass ratio of the reducing agent to the copper salt in the step 1 is 0.3:1 to 0.5:1; the mass ratio of the auxiliary agent to the copper salt in the step 1 is 0.025:1 to 0.125:

1.

5. The method for preparing silver-coated copper powder according to claim 1, characterized in that: The reaction temperature in step 1 is 80-120° C., and the reaction time is 1-3 hours.

6. The method for preparing silver-coated copper powder according to claim 1, characterized in that: The dispersant is one or more of alkylphenol polyoxyethylene ether, polyvinyl pyrrolidone and sodium citrate; the solvent is one or more of deionized water and distilled water.

7. The method for preparing silver-coated copper powder according to claim 1, characterized in that: The silver salt in step 2 is silver sulfate; the complexing agent in step 2 is one or more of disodium ethylenediaminetetraacetate, polyvinylpyrrolidone, ammonia water, and organic amines.

8. The method for preparing silver-coated copper powder according to claim 1, characterized in that: In the step 2, 400-600 mL of solvent is added to every 5 g of silver salt; the mass ratio of the complexing agent to the silver salt is 3:1-6:1; and the mass ratio of the dispersant to the silver salt is 0.5:1-3:

1.

9. The method for preparing silver-coated copper powder according to claim 1, characterized in that: The dripping rate in the step 3 is 6-10 mL / min, and the reaction time is 30-90 min.

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