Preparation method of high-sinterability nano-copper

Abstract

The invention discloses a preparation method of nano-copper with high sintering property, nano-copper powder with uniform particle size and excellent sintering property is prepared by adopting a chemical synthesis method, and copper powder with different sizes can be prepared by adjusting the molar ratio of copper salt to a reducing agent and the reaction temperature under the action of a complexing agent. The prepared catalyst has the characteristics of no hard agglomeration, high purity, relatively high specific surface area and relatively high surface activity, meanwhile, excellent high sinterability is maintained, and the preparation method is simple and easy for large-scale application.

Description

Technical Field

[0001] The invention relates to the field of nonferrous metal materials, and in particular to a method for preparing high-sinterability nano copper. Background Art

[0002] As electronic devices develop towards higher power density, smaller size and higher integration, nano copper powder, as an emerging high-end material, is crucial to meeting the development needs of new generation communications, new energy and other industries. High sintering copper powder can achieve low temperature sintering to form high reliability and high density PCB interconnections, which is of great significance for improving the electrical performance and thermal management capabilities of electronic equipment.

[0003] However, the practical application of nano copper powder still faces a series of challenges, including the control of particle size uniformity, the alleviation of agglomeration and the maintenance of high sintering performance. These problems need to be solved urgently. Therefore, developing a preparation process that is both simple and suitable for large-scale industrial production to stably produce nano copper powder with high sintering activity has become the focus of current research. Summary of the invention

[0004] The main purpose of the present invention is to provide a method for preparing highly sinterable nano copper.

[0005] To achieve the above object, the technical solution adopted by the present invention is:

[0006] A method for preparing highly sinterable nano copper comprises the following steps:

[0007] Step 1: adding a certain amount of sodium hydroxide to deionized water, stirring evenly, and cooling to room temperature to obtain a sodium hydroxide solution. The sodium hydroxide provides an alkaline environment for subsequent reactions, helps to control the rate of the reduction reaction, and better synthesizes copper nanoparticles;

[0008] Step 2: Evenly mix copper nitrate, complexing agent, dispersant and sodium hydroxide solution, heat and stir at 60-90° C. for 3-5 hours, control the heating rate at 2-3° C. / min, and use gentle water bath heating to avoid local overheating or uneven temperature that may be caused by direct heating. The temperature of the reaction system is accurately controlled to evenly mix copper nitrate, complexing agent, dispersant and sodium hydroxide solution, which can ensure that each component is evenly distributed in the solution, promote the reaction, and provide a better reaction environment for the subsequent reduction reaction;

[0009] Step 3: Add an appropriate amount of reducing agent according to the concentration of copper nitrate, stir evenly, react for 5-7 hours, the molar ratio of reducing agent to copper nitrate is 1:1.2-1:1.5, and use a chemical method to use the reducing agent to reduce copper ions into copper particles. The selection and concentration of the reducing agent will directly affect the reduction rate of copper ions, and copper powders of different particle sizes and purities are obtained;

[0010] Step 4: After the reaction is completed, the obtained product is immersed in a low concentration p-aminobenzenesulfonylaminothiazole solution at a temperature of 50-80° C. for 5-10 minutes, washed with water and dried to obtain nano copper powder.

[0011] Furthermore, the concentration of the p-aminobenzenesulfonylamide thiazole is 0.02M-0.05M. p-aminobenzenesulfonylamide thiazole contains sulfonamide and amino groups. A short-time immersion in a low-concentration p-aminobenzenesulfonylamide thiazole solution can form a thin film on the surface of the copper powder by chemical adsorption, thereby improving the dispersibility and sintering performance of the copper powder.

[0012] Furthermore, the mass concentration of the sodium hydroxide solution in step 1 is 35-38%.

[0013] Furthermore, the concentration of the copper nitrate is 0.4-0.6M.

[0014] Furthermore, the complexing agent is one or more of ethylenediamine, potassium sodium tartrate, and sodium citrate, and the concentration of the complexing agent is 3-5M.

[0015] Furthermore, the dispersant is one or more of polyvinyl pyrrolidone K15, polyvinyl pyrrolidone K30, polyvinyl pyrrolidone K60, and cyclodextrin.

[0016] Furthermore, the concentration of the dispersant is 15-25 wt%.

[0017] Furthermore, the reducing agent is one or more of hydrazine hydrate, potassium borohydride, and sodium hypophosphite.

[0018] Furthermore, the drying condition is forced air drying at 60-80°C for 3-6 hours.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] It can effectively prevent the precipitation of copper ions and control the reaction rate

[0021] 1. The invention adopts sodium hydroxide, a complexing agent, a dispersant, a copper salt and a reducing agent to prepare nano copper particles. By adjusting the molar ratio of the copper salt to the reducing agent and the reaction temperature, the rate of the reduction reaction is controlled and the growth of the copper powder crystal nucleus is further controlled to prepare nano copper powders with different particle sizes. Sodium hydroxide provides a suitable alkaline environment for the reaction, the adsorption of the complexing agent on copper ions controls the rate of the reduction reaction, and the dispersant can effectively prevent the copper powder from agglomerating during the synthesis process, thereby ensuring its good dispersion state. By adjusting the concentration of the reducing agent and the copper salt, copper nano particles with average particle sizes of 200 nm, 500 nm and 800 nm are prepared.

[0022] 2. p-Aminobenzenesulfonylamide thiazole contains sulfonamide and amino groups. The sulfonamide reacts with metallic copper to form a protective film, which gives it a good corrosion inhibition effect. The amino group can increase the surface properties of copper powder and enhance the dispersibility and stability of copper powder in the solution. Short-term immersion in a low-concentration p-aminobenzenesulfonylamide thiazole solution can improve the dispersibility and sintering properties of copper powder.

[0023] 3. Compared with the existing chemical method, the process is simple, the particle size is uniform, there is no hard agglomeration, the purity is higher, the surface activity is stronger, and the sintering property is high. The reaction conditions are mild and no special equipment is required. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is a scanning electron microscope image of the nano copper powder prepared in Example 1;

[0025] Figure 2 This is a scanning electron microscope image of the nano copper powder prepared in Example 2;

[0026] Figure 3 This is a scanning electron microscope image of the nano copper powder prepared in Example 3. DETAILED DESCRIPTION

[0027] 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.

[0028] Example 1

[0029] Add 600g of NaOH to 1L of deionized water, stir for 30min to mix evenly, cool to room temperature to obtain a sodium hydroxide solution; add 75g of Cu(NO3)2, stir until fully dissolved, then add 300mL of EDA and 200g of PVP k60 in sequence, heat to 80°C at a heating rate of 2°C / min, stir for 4h until evenly dispersed, add 48mL of hydrazine hydrate, stir and react for 6h, settle and wash the product, soak it in a 0.02M p-aminobenzenesulfonylthiazole solution for 5min, wash with water and dry in a blast oven for 5h to obtain a nano copper powder with an average particle size of 200nm, such as Figure 1 shown.

[0030] Example 2

[0031] Add 600g of NaOH to 1L of deionized water, stir for 30min to mix evenly, cool to room temperature to obtain a sodium hydroxide solution; add 75g of Cu(NO3)2, stir until fully dissolved, then add 300mL of EDA and 200g of PVP k60 in sequence, heat to 75°C at a heating rate of 2°C / min, stir for 4h until evenly dispersed, add 44mL of hydrazine hydrate, stir and react for 6h, settle and wash the product, soak it in a 0.03M p-aminobenzenesulfonylthiazole solution for 5min, wash with water and dry in a blast oven for 5h to obtain a nano copper powder with an average particle size of 500nm, such as Figure 2 shown.

[0032] Example 3

[0033] Add 600g of NaOH to 1L of deionized water, stir for 30min to mix evenly, cool to room temperature to obtain a sodium hydroxide solution; add 75g of Cu(NO3)2, stir until fully dissolved, then add 300mL of EDA and 200g of PVP k60 in sequence, heat to 60°C at a heating rate of 2°C / min, stir for 4h until evenly dispersed, add 38mL of hydrazine hydrate, stir and react for 6h, settle and wash the product, soak it in a 0.04M p-aminobenzenesulfonylthiazole solution for 5min, wash with water and dry in a blast oven for 5h to obtain a nano copper powder with an average particle size of 800nm, such as Figure 3 shown.

[0034] Comparative Example 1

[0035] Add 600g NaOH to 1L deionized water, stir for 30min to mix evenly, cool to room temperature to obtain a sodium hydroxide solution; add 75g Cu(NO3)2, stir until fully dissolved, add 300mL EDA and 200g PVP k60 in sequence, heat to 80℃ at a heating rate of 2℃ / min, stir for 4h until evenly dispersed, add 48mL hydrazine hydrate, stir and react for 6h, settle and wash the product, and dry it in a blast oven for 5h to obtain a nano copper powder with an average particle size of 200nm.

[0036] Comparative Example 2

[0037] Add 600g NaOH to 1L deionized water, stir for 30min to mix evenly, cool to room temperature to obtain a sodium hydroxide solution; add 75g Cu(NO3)2, stir until fully dissolved, add 300mL EDA and 200g PVP k60 in sequence, heat to 75℃ at a heating rate of 2℃ / min, stir for 4h until evenly dispersed, add 44mL hydrazine hydrate, stir and react for 6h, settle and wash the product, and dry it in a blast oven for 5h to obtain a nano copper powder with an average particle size of 500nm.

[0038] Comparative Example 3

[0039] Add 600g NaOH to 1L deionized water, stir for 30min to mix evenly, cool to room temperature to obtain sodium hydroxide solution; add 75g Cu(NO3)2, stir until fully dissolved, add 300mL EDA and 200g PVP k60 in sequence, heat to 60℃ at a heating rate of 2℃ / min, stir for 4h until evenly dispersed, add 38mL hydrazine hydrate, stir and react for 6h, settle and wash the product, and dry it in a blast oven for 5h to obtain nano copper powder with an average particle size of 800nm.

[0040] Table 1

[0041]

[0042] The above description is only a preferred embodiment of the present invention, and the protection scope of the present invention is not limited to the above embodiment. Any equivalent modifications or changes made by ordinary technicians in this field based on the contents disclosed by the present invention should be included in the protection scope recorded in the claims.

Claims

1. A method for preparing highly sinterable nano copper, comprising the following steps: Step 1, adding a certain amount of sodium hydroxide to deionized water, stirring evenly, and cooling to room temperature to obtain a sodium hydroxide solution; Step 2: Evenly mix copper nitrate, complexing agent, dispersant and sodium hydroxide solution, heat and stir at 60-90°C for 3-5h, and control the heating rate at 2-3°C / min; Step 3: Add an appropriate amount of reducing agent according to the concentration of copper nitrate, stir evenly, and react for 5-7 hours. The molar ratio of reducing agent to copper nitrate is 1:1.2-1:1.5; Step 4: After the reaction is completed, the obtained product is immersed in a low concentration p-aminobenzenesulfonylaminothiazole solution at a temperature of 50-80° C. for 5-10 minutes, washed with water and dried to obtain nano copper powder.

2. The method for preparing highly sinterable nano copper according to claim 1, characterized in that: The concentration of the p-aminobenzenesulfonylaminothiazole is 0.02-0.05M.

3. The method for preparing highly sinterable nano copper according to claim 1, characterized in that: The mass concentration of the sodium hydroxide solution in step 1 is 35%-38%.

4. The method for preparing highly sinterable nano copper according to claim 1, characterized in that: The concentration of the copper nitrate is 0.4-0.6M.

5. The method for preparing highly sinterable nano copper according to claim 1, characterized in that: The complexing agent is one or more of ethylenediamine, potassium sodium tartrate, and sodium citrate, and the concentration of the complexing agent is 3-5M.

6. The method for preparing highly sinterable nano copper according to claim 1, characterized in that: The dispersant is one or more of polyvinyl pyrrolidone K15, polyvinyl pyrrolidone K30, polyvinyl pyrrolidone K60 and cyclodextrin.

7. The method for preparing highly sinterable nano copper according to claim 6, characterized in that: The concentration of the dispersant is 15-25 wt %.

8. The method for preparing highly sinterable nano copper according to claim 1, characterized in that: The reducing agent is one or more of hydrazine hydrate, potassium borohydride and sodium hypophosphite.

9. The method for preparing highly sinterable nano copper according to claim 1, characterized in that: The drying condition is forced air drying at 60-80°C for 3-6 hours.

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