Silver-coated copper powder and preparation method thereof
By using a one-pot method to prepare silver-coated copper powder, controlling the acidic environment and adding corrosion inhibitors, the high cost and copper powder surface etching problems of traditional methods are solved, achieving uniform coating and improved conductivity of the silver-coated copper powder.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-09
- Publication Date
- 2026-03-27
AI Technical Summary
Traditional methods for preparing silver-coated copper powder suffer from problems such as increased costs due to multiple acid washing steps and the inability to control the reduction reaction rate under alkaline or neutral conditions, resulting in excessive etching and localized defects on the copper powder surface.
Silver-coated copper powder was prepared using a one-pot method. By controlling the acidic environment of the first solution and adding a corrosion inhibitor, the reduction rate of silver was suppressed. Dispersants and complexing agents were used to promote uniform dispersion of copper powder and uniform coating of silver. Vacuum drying was then used to form a dense silver layer.
A silver-coated copper powder with uniform particle size and good coating was obtained, which improved the conductivity and reduced the production cost.
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Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the technical field of metal materials, in particular to a silver-coated copper powder and a preparation method thereof. BACKGROUND
[0002] Silver powder is the most widely used conductive filler. However, silver has small reserves and high price, and silver migration phenomenon easily occurs in the use process, which cannot meet the requirements of high-performance electronic components. Copper has a conductive capacity only second to silver, and is a good substitute for silver in terms of performance. However, copper powder is easy to oxidize, which reduces its conductivity and stability. After coating the surface of copper powder with silver, the internal copper powder reduces direct contact with air, thereby significantly improving the anti-oxidation ability and overall stability of the copper powder, and reducing production cost. Traditional silver-coated copper powder preparation has the following problems: 1) multi-step acid washing leads to increased cost; 2) under alkaline or neutral conditions, the reduction reaction speed cannot be controlled, which makes the replacement reaction between silver and copper the main reaction in the coating process, and easily causes excessive etching of the surface of copper powder, forming local defects.
[0003] Therefore, it is urgent to develop a preparation method of silver-coated copper powder. SUMMARY
[0004] The present application aims to at least solve one of the technical problems in the related art. To this end, the present application provides a silver-coated copper powder and a preparation method thereof, and the obtained silver-coated copper powder has uniform particle size and good coating.
[0005] To this end, the present application provides a method for preparing a silver-coated copper powder, comprising the following steps: mixing copper powder, a corrosion inhibitor and a first solution to obtain a second solution; the pH of the first solution is 1.5-3.5; the first solution comprises a dispersant, a reducing agent and a first complexing agent; the first complexing agent comprises one or more of ethylenediaminetetraacetic acid, ethylenediaminetetraacetate, diethylenetriamine pentaacetic acid and diethylenetriamine pentaacetate; mixing the second solution and a silver salt solution, and vacuum drying to obtain a silver-coated copper powder; the silver salt solution comprises a second complexing agent; the second complexing agent comprises one or more of citric acid and citrate.
[0006] The silver-coated copper powder is prepared by the one-pot method, and has the advantages of simple operation process, low production cost, strong operability, high repeatability, and low requirement for equipment; the reducing agent is arranged in the first solution, and the first solution is controlled to be in an acidic environment, so that the reduction rate of silver can be inhibited, and the silver can be more uniformly and densely coated on the surface of copper; the corrosion inhibitor can avoid the formation of primary cells by the local active sites on the surface of copper particles, avoid the continuous displacement reaction between silver ions and copper particles at the sites, and avoid the excessive corrosion of copper particles to form local defects, so that the silver is not uniformly coated on the surface of copper; and the silver-coated copper powder obtained by the method has the advantages of spherical shape, uniform particle size, and good coating.
[0007] In some embodiments of the present application, the pH of the first solution is 2.0-3.0. Thus, the pH of the first solution is low, which can further inhibit the reduction rate of silver and promote the formation of uniform and dense coating of silver on the surface of copper.
[0008] In some embodiments of the present application, the corrosion inhibitor includes one or more of thiourea, mercaptan, imidazole, quaternary ammonium salt, chromate, nitrite, molybdate, and phosphate. Thus, the corrosion inhibitor can avoid the formation of primary cells by the local active sites on the surface of copper particles, avoid the continuous displacement reaction between silver ions and copper particles at the sites, and avoid the excessive corrosion of copper particles to form local defects.
[0009] In some embodiments of the present application, the dispersant includes one or more of polyvinylpyrrolidone, polyethylene glycol, gelatin, cellulose or its derivatives, and gum arabic. Thus, the dispersant can help promote the uniform dispersion of copper powder in the first solution.
[0010] In some embodiments of the present application, the reducing agent includes one or more of ascorbic acid or its derivatives, hydrazine hydrate, glucose, and potassium sodium tartrate. Thus, the silver salt is reduced by the reducing agent to control the reaction rate and facilitate uniform coating.
[0011] In some embodiments of the present application, the mass ratio of the corrosion inhibitor to the copper powder is (0.01-0.2):1. Thus, the mass ratio of the corrosion inhibitor to the copper powder is controlled, the lone pair electrons of S or N are coordinated with the surface of Cu to form a molecular buffer layer, the interface defects are reduced, the excessive etching is inhibited, and the silver layer can be uniformly deposited on the surface of the copper powder.
[0012] In some embodiments of the present application, the mass ratio of the dispersant to the copper powder is (0.01-0.05):1. Thus, the dispersant can help promote the uniform dispersion of copper powder in the first solution.
[0013] In some embodiments of the present application, the ratio of the amount of substance of the reducing agent to the silver in the silver salt solution is (0.1-1):1. In this way, by reducing the silver salt with the reducing agent, the rate of the reaction is controlled, and uniform coating is facilitated.
[0014] In some embodiments of the present application, the mass ratio of the first complexing agent to the copper powder is (0.1-0.5):1. In this way, after the first complexing agent reacts with copper ions to form a stable complex, the concentration of free copper ions in the solution is reduced, and the reaction rate of copper ions in the subsequent reduction reaction is slowed down, thereby effectively regulating the size of the generated copper particles.
[0015] In some embodiments of the present application, the ratio of the amount of substance of the second complexing agent to the silver in the silver salt solution is (0.1-2):1. In this way, the silver ions in the silver salt react with the second complexing agent to slow down the reaction rate of the subsequent displacement reaction, thereby facilitating the uniformity of the silver coating on copper.
[0016] In some embodiments of the present application, the copper powder, the corrosion inhibitor, and the first solution are mixed at 20-40°C. In this way, the surface of the copper powder is activated, and the copper powder is prevented from being excessively oxidized by the acid.
[0017] In some embodiments of the present application, the second solution and the silver salt solution are mixed at 20-40°C. In this way, the silver layer can be uniformly deposited on the surface of the copper powder, and a dense and continuous silver coating layer is formed.
[0018] In some embodiments of the present application, the ratio of the amount of substance of the copper powder to the silver in the silver salt solution is (1-20):1.
[0019] In some embodiments of the present application, the pH of the silver salt solution is 2-3. In this way, the silver salt solution is acidic, and the activation and deposition of silver ions on the surface of the copper powder are facilitated under acidic conditions, thereby forming a firm silver coating layer.
[0020] In some embodiments of the present application, the silver salt solution is added to the second solution and mixed.
[0021] In some embodiments of the present application, the silver salt solution is added to the second solution for 5-30 min. In this way, the contact time of the silver salt solution with copper can be prolonged, the displacement reaction rate is slowed down, the silver grows slowly on the surface of the copper particles, and the uniformity of the coating is improved.
[0022] In some embodiments of the present application, the particle size of the copper powder is 0.5-10 μm.
[0023] The second aspect of the present application provides a silver-coated copper powder obtained by the above method. Thus, the silver-coated copper powder of the present application has excellent electrical conductivity.
[0024] Additional aspects and advantages of the present application will be set forth in part in the description which follows, and in part will become apparent to those skilled in the art upon examination of the following and / or can be learned by practice of the present application. BRIEF DESCRIPTION OF DRAWINGS
[0025] The above and / or additional aspects and advantages of the present application will become apparent and be readily appreciated from the following description, including the appended drawings, wherein: Figure 1 A scanning electron microscope image of the silver-coated copper powder of Example 1 of the present application is shown; Figure 2 A scanning electron microscope image of the silver-coated copper powder of Example 2 of the present application is shown; Figure 3 A cross-sectional scanning electron microscope image of the silver-coated copper powder of Example 2 of the present application is shown; Figure 4 A scanning electron microscope image of the silver-coated copper powder of Comparative Example 1 of the present application is shown; Figure 5 A scanning electron microscope image of the silver-coated copper powder of Comparative Example 3 of the present application is shown; Figure 6 A cross-sectional scanning electron microscope image of the silver-coated copper powder of Comparative Example 3 of the present application is shown.
[0026] Figure 7 A cross-sectional scanning electron microscope image of the silver-coated copper powder of Comparative Example 3 of the present application is shown. DETAILED DESCRIPTION
[0027] Embodiments of the present application are described in detail below. The embodiments described below are examples for explaining the present application and should not be construed as limiting the present application.
[0028] It should be noted that the terms "first", "second" are used only for descriptive purposes and should not be construed as indicating or implying relative importance or a specific number of the technical features indicated. Thus, the features defined with "first", "second" can explicitly or implicitly include one or more of the features. Further, in the description of the present application, the meaning of "a plurality of" is two or more, unless otherwise specified.
[0029] The first aspect of the present application provides a method for preparing a silver-coated copper powder, comprising the steps of: S1, mixing copper powder, corrosion inhibitor and first solution to obtain second solution; the pH of the first solution is 1.5-3.5; the first solution comprises dispersant, reducing agent and first complexing agent; the first complexing agent comprises one or more of ethylenediaminetetraacetic acid, ethylenediaminetetraacetic acid salt, diethylenetriaminepentaacetic acid, diethylenetriaminepentaacetic acid salt.
[0030] In some embodiments of the present application, the ethylenediaminetetraacetic acid salt comprises disodium ethylenediaminetetraacetate (EDTA-2Na).
[0031] As an example, the pH of the first solution can be 1.5, 1.6, 1.7, 1.8, 1.9, 2, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, 3, 3.1, 3.2, 3.3, 3.4, 3.5.
[0032] In some embodiments of the present application, the pH of the first solution is 2.0-3.0. In this way, the pH of the first solution is lower, which can further inhibit the reduction rate of silver and promote the formation of a uniform and dense coating of silver on the surface of copper.
[0033] In some embodiments of the present application, the particle size of the copper powder is 0.5-10 μm.
[0034] As an example, the particle size of the copper powder can be 0.5, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 μm.
[0035] In some embodiments of the present application, the corrosion inhibitor comprises one or more of thiourea, mercaptan, imidazole, quaternary ammonium salt, chromate, nitrite, molybdate, phosphate. In this way, the corrosion inhibitor can avoid the formation of local active sites on the surface of copper particles, avoid continuous displacement reaction of silver ions and copper particles at the site, and excessive corrosion of copper particles to form local defects.
[0036] In some embodiments of the present application, the mass ratio of the corrosion inhibitor to the copper powder is (0.01-0.2):1. In this way, by controlling the mass ratio of the corrosion inhibitor to the copper powder, the lone pair electrons of S or N are coordinated with the surface of Cu to form a molecular buffer layer, reduce interface defects, inhibit excessive etching, and enable the silver layer to be uniformly deposited on the surface of the copper powder.
[0037] As an example, the mass ratio of the corrosion inhibitor to the copper powder can be 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.1, 0.2.
[0038] In some embodiments of the present application, the dispersant comprises one or more of polyvinylpyrrolidone, polyethylene glycol, gelatin, cellulose or its derivatives, gum arabic. Thereby, it helps to promote the uniform dispersion of the copper powder in the first solution.
[0039] In some embodiments of the present application, the cellulose or its derivatives comprise one or more of cellulose, carboxymethyl cellulose, methyl cellulose, ethyl cellulose, hydroxypropyl methyl cellulose.
[0040] In some embodiments of the present application, the mass ratio of the dispersant to the copper powder is (0.01-0.05):1. Thereby, it helps to promote the uniform dispersion of the copper powder in the first solution.
[0041] For example, the mass ratio of the dispersant to the copper powder can be 0.01, 0.02, 0.03, 0.04, 0.05.
[0042] In some embodiments of the present application, the reducing agent comprises one or more of ascorbic acid or its derivatives, hydrazine hydrate, glucose, potassium sodium tartrate.
[0043] In some embodiments of the present application, the ascorbic acid or its derivatives comprise one or more of ascorbic acid, 3-O-ethyl ascorbic acid ether, ascorbic acid glucoside, ascorbic acid magnesium phosphate, ascorbic acid palmitate, sodium ascorbate, calcium ascorbate. Thereby, by reducing the silver salt with the reducing agent, the rate of the reaction is controlled, which is conducive to uniform coating.
[0044] In some embodiments of the present application, the molar ratio of the reducing agent to the silver in the silver salt solution is (0.1-1):1. Thereby, by reducing the silver salt with the reducing agent, the rate of the reaction is controlled, which is conducive to uniform coating.
[0045] For example, the molar ratio of the reducing agent to the silver in the silver salt solution can be 0.1, 0.5, 0.6, 0.7, 0.8, 0.9, 1.
[0046] In some embodiments of the present application, the mass ratio of the first complexing agent to the copper powder is (0.1-0.5):1. Thereby, after the first complexing agent reacts with the copper ions to form a stable complex, the concentration of free copper ions in the solution is reduced, which can slow down the reaction rate of the copper ions in the subsequent reduction reaction, thereby effectively controlling the size of the generated copper particles.
[0047] For example, the mass ratio of the first complexing agent to the copper powder can be 0.1, 0.2, 0.3, 0.4, 0.5.
[0048] In some embodiments of the present application, the first solution further comprises a pH adjusting agent, and the pH adjusting agent comprises at least one of sulfuric acid, nitric acid.
[0049] In some embodiments of the present application, the mixing of the copper powder, the corrosion inhibitor and the first solution is performed at 20-40℃. In this way, the surface of the copper powder is activated, and the copper powder is prevented from being excessively oxidized by the acid.
[0050] For example, the mixing of the copper powder, the corrosion inhibitor and the first solution can be performed at 20, 25, 30, 35, 40℃.
[0051] In some embodiments of the present application, the mixing of the copper powder, the corrosion inhibitor and the first solution is performed for 10-30min.
[0052] For example, the mixing of the copper powder, the corrosion inhibitor and the first solution can be performed for 10, 20, 30min.
[0053] S2, mixing the second solution and a silver salt solution, and vacuum drying to obtain a silver-coated copper powder; the silver salt solution comprises a second complexing agent; the second complexing agent comprises one or more of citric acid, citrate.
[0054] In some embodiments of the present application, the citrate comprises one or more of sodium citrate or a hydrate thereof, potassium citrate or a hydrate thereof, calcium citrate or a hydrate thereof, magnesium citrate or a hydrate thereof.
[0055] In some embodiments of the present application, the ratio of the amount of substance of the second complexing agent to the amount of substance of silver in the silver salt solution is (0.1-2):1. In this way, the silver ions in the silver salt are complexed with the second complexing agent, which slows down the reaction rate of the subsequent displacement reaction, and helps to improve the uniformity of the silver coating on the copper.
[0056] For example, the ratio of the amount of substance of the second complexing agent to the amount of substance of silver in the silver salt solution can be 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1, 1.2, 1.5, 1.8, 2.
[0057] In some embodiments of the present application, the ratio of the amount of substance of the copper powder to the amount of substance of silver in the silver salt solution is (1-20):1.
[0058] For example, the ratio of the amount of substance of the copper powder to the amount of substance of silver in the silver salt solution can be 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20.
[0059] In some embodiments of the present application, the pH of the silver salt solution is 2-3. In this way, the silver salt solution is acidic, which facilitates the activation and deposition of silver ions on the surface of the copper powder under acidic conditions, forming a firm silver coating layer.
[0060] As an example, the pH of the silver salt solution can be 2, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, 3.
[0061] In some embodiments of the present application, the silver salt includes one or more of silver nitrate, silver fluoride, silver perchlorate, silver sulfate.
[0062] In some embodiments of the present application, the silver salt solution further includes a pH adjusting agent, and the pH adjusting agent includes at least one of sulfuric acid, nitric acid.
[0063] In some embodiments of the present application, the temperature of the vacuum drying is 40-80°C. In this way, by the vacuum drying process, the moisture of the silver-coated copper powder is evaporated, obtaining a stable silver-coated copper powder.
[0064] As an example, the temperature of the vacuum drying can be 40, 50, 60, 70, 80°C.
[0065] In some embodiments of the present application, the vacuum degree of the vacuum drying is 1-1000 Pa.
[0066] As an example, the vacuum degree of the vacuum drying can be 1, 10, 50, 100, 500, 800, 1000 Pa.
[0067] In some embodiments of the present application, the time of the vacuum drying is 10-20 h.
[0068] As an example, the time of the vacuum drying can be 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20 h.
[0069] In some embodiments of the present application, the second solution and the silver salt solution are mixed at 20-40°C. In this way, the silver layer can be uniformly deposited on the surface of the copper powder, which facilitates the formation of a dense and continuous silver coating layer.
[0070] As an example, the second solution and the silver salt solution can be mixed at 20, 25, 30, 35, 40°C.
[0071] In some embodiments of the present application, the silver salt solution is added to the second solution for mixing.
[0072] In some embodiments of the present application, the silver salt solution is added to the second solution for 5-30 min. In this way, the time for the silver salt solution to contact the copper can be prolonged, the replacement reaction rate can be slowed down, and the silver can grow slowly on the surface of the copper particles, which is beneficial to improving the uniformity of the coating.
[0073] For example, the silver salt solution can be added to the second solution for 5, 10, 15, 20, 25, or 30 min.
[0074] The second aspect of the present application provides a silver-coated copper powder obtained by the above method. In this way, the silver-coated copper powder of the present application has excellent electrical conductivity.
[0075] The schemes of the present disclosure will be explained below in conjunction with examples. Those skilled in the art will understand that the following examples are only used to illustrate the present disclosure and should not be regarded as limiting the scope of the present disclosure. If the specific techniques or conditions are not specified in the examples, they are carried out according to the techniques or conditions described in the literature in the art or according to the product instructions. If the reagents or instruments are not specified by the manufacturer, they are all conventional products that can be obtained commercially.
[0076] Example 1 The silver-coated copper powder of the present example is prepared by the following steps: 1. Prepare the first solution: At room temperature, take 1000 g of deionized water as the base solvent, and then sequentially add 0.1 g of carboxymethyl cellulose, a 6.8% nitric acid solution, 1.5 g of disodium ethylenediaminetetraacetate (EDTA-2Na), and 1.76 g of ascorbic acid (10 mmol) to the base solvent. After all the components are fully mixed and dissolved, the pH value of the first solution is 2.5.
[0077] 2. Copper powder pretreatment: Ultrasonically disperse 10 g of copper powder with a particle size of 5 μm (0.157 mol) in the first solution, control the temperature to be 25°C, and disperse for 20 minutes. Then add 1 g of the corrosion inhibitor thiourea to obtain the second solution. 3. Prepare the silver salt solution: Add 1.70 g of silver nitrate (AgNO3, wherein the amount of substance of silver is 10 mmol) to 400 g of deionized water and stir to dissolve. Then add 5 g of a 6.8% nitric acid (HNO3) solution and 1.4 g of citric acid (7.3 mmol) to prepare the silver salt solution and maintain the temperature at 25°C. The pH value of the silver salt solution is 2.5. 4. Reaction stage: Add the silver salt solution to the second solution dropwise, and the dropwise addition time is 15 min at a speed of 25 mL / min. After the dropwise addition is completed, stop the reaction. 5. Post-treatment: Solid-liquid separation, wash the solid with water until neutral, then perform ethanol dehydration, and vacuum dry at 60°C for 12 h. The vacuum degree of the vacuum drying is 10 Pa.
[0078] The scanning electron microscope image of the silver-coated copper powder in this embodiment is shown below. Figure 1 As shown, the silver-coated copper powder is completely coated, with a smooth surface, no gaps or holes, and is evenly dispersed without agglomeration.
[0079] Example 2 The silver-coated copper powder of this embodiment is prepared by the following steps: 1. Preparation of the first solution: At room temperature, first take 1000g of deionized water as the base solvent, and add 0.5g of gum arabic, 6.8% nitric acid solution, 5g of disodium ethylenediaminetetraacetate (EDTA-2Na), and 0.88g of 3-O-ethyl ascorbic acid ether (CAS No. 86404-04-8, 4.3mmol) in sequence. After all the above components are fully mixed and dissolved, the pH of the first solution is 2.0.
[0080] 2. Copper powder pretreatment: 10g of copper powder with a particle size of 5μm is ultrasonically dispersed in the first solution, the temperature is controlled at 25℃, and the treatment is carried out for 20 minutes. Then, 1g of corrosion inhibitor thiourea is added to obtain the second solution. 3. Preparation of silver salt solution: Add 1.70g of silver nitrate to 400g of deionized water and stir to dissolve. Then add 10g of 6.8% nitric acid solution and 5.88g of sodium citrate dihydrate (20.0 mmol) to prepare a silver salt solution. Keep the temperature at 25℃ and the pH of the silver salt solution is 2.5. 4. Reaction stage: The silver salt solution was added dropwise to the second solution over a period of 15 minutes at a rate of 25 mL / min. The reaction was stopped after the addition was completed. At this point, the concentration of copper ions in the system was 0.3 g / L. 5. Post-processing: Solid-liquid separation, take the solid, wash it with water until neutral, then dehydrate it with ethanol, and vacuum dry it at 60℃ for 12h. The vacuum degree of vacuum drying is 10Pa.
[0081] The scanning electron microscope image of the silver-coated copper powder in this embodiment is shown below. Figure 2 and Figure 3 As shown, the synthesized silver-coated copper powder has a complete coating, is evenly dispersed, and has no defects on the cut surface. In this embodiment, the silver content in the silver-coated copper powder is 10% by mass.
[0082] Comparative Example 1 The preparation method of the silver-coated copper powder in this comparative example differs from that in Example 1 only in that the nitric acid content in the first solution in step 1 is adjusted to control the pH value of the first solution to 3.8; the remaining steps are carried out in accordance with the method in Example 1.
[0083] The scanning electron microscope image of the silver-coated copper powder in this comparative example is shown below. Figure 4As shown in the scanning electron microscope (SEM) image, the surface of the synthesized silver-coated copper powder has many small protruding particles.
[0084] Comparative Example 2 The preparation method of the silver-coated copper powder of the present comparative example is different from that of Example 1 only in that the present comparative example adjusts the content of nitric acid in the first solution in Step 1, and controls the pH value of the first solution to be 1.2; the remaining steps are performed according to the method in Example 1.
[0085] Comparative Example 3 The preparation method of the silver-coated copper powder of the present comparative example is different from that of Example 1 only in that the present comparative example omits the corrosion inhibitor thiourea in Step 2; the remaining steps are performed according to the method in Example 1; wherein the copper ion concentration in the system obtained in Step 4 is higher than 0.3 g / L.
[0086] The scanning electron microscope (SEM) image of the silver-coated copper powder of the present comparative example is shown in Figure 5 As shown in the scanning electron microscope (SEM) image of the cross section of the silver-coated copper powder Figure 6-7 It can be seen that the surface of the synthesized silver-coated copper powder has notches, and the cross section of the silver-coated copper powder shows obvious defects, which is a structure discontinuity phenomenon caused by copper particle etching due to excessive displacement reaction caused by the absence of corrosion inhibitor.
[0087] Comparative Example 4 The preparation method of the silver-coated copper powder of the present comparative example is different from that of Example 1 only in that the present comparative example omits carboxymethyl cellulose in Step 1; the remaining steps are performed according to the method in Example 1.
[0088] Comparative Example 5 The preparation method of the silver-coated copper powder of the present comparative example is different from that of Example 1 only in that the present comparative example omits ascorbic acid in Step 1; the remaining steps are performed according to the method in Example 1.
[0089] Comparative Example 6 The preparation method of the silver-coated copper powder of the present comparative example is different from that of Example 1 only in that the present comparative example adjusts the replacement in Step 1 to be citric acid; the remaining steps are performed according to the method in Example 1.
[0090] Comparative Example 7 The preparation method of the silver-coated copper powder of the present comparative example is different from that of Example 1 only in that the present comparative example adjusts the replacement in Step 3 to be ethylenediaminetetraacetic acid disodium salt; the remaining steps are performed according to the method in Example 1.
[0091] Test Example The raw materials were weighed according to the following quality percentage: epoxy resin 2.6%, glyceride 0.8%, dodecenyl succinic anhydride 0.1%, solvent 3.5% (butyl carbitol acetate 2.3%, terpineol 1.2%), nano-silver powder 21.75% (average particle size 300 nm), silver-coated copper powder prepared in the examples and comparative examples 71.25%. The raw materials were weighed, mixed uniformly, and then rolled 8 times by a three-roll mill to a fineness of less than 5 μm to prepare a silver-coated copper powder heterojunction cell slurry. After screen printing, the slurry was cured at 170°C for 5 min and sintered at 200°C for 10 min. The micro-resistance meter was used to obtain the 20 μm opening line resistance and the 20 μm opening contact resistance.
[0092] Table 1
[0093] Table 1 shows the conductive properties of the silver-coated copper powder of the examples and comparative examples of the present application. As shown in Table 1, the line resistance and contact resistance of the slurry prepared from the silver-coated copper powder of the examples are lower than those of the comparative examples, and the conductive properties are better.
[0094] In the description of the present specification, the description of the terms "one embodiment", "some embodiments", "an example", "a specific example", "some embodiments" or "some examples" and the like means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In the present specification, the illustrative description of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any appropriate manner in any one or more embodiments or examples. In addition, the different embodiments or examples described in the present specification and the features of the different embodiments or examples can be combined and combined by those skilled in the art without contradiction.
[0095] Although the embodiments of the present application have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present application, and those skilled in the art can make changes, modifications, replacements and variations to the above embodiments within the scope of the present application.
Claims
1. A method for preparing silver-coated copper powder, characterized in that, Includes the following steps: Copper powder, corrosion inhibitor, and a first solution are mixed to obtain a second solution; the pH of the first solution is 1.5-3.5; the first solution includes a dispersant, a reducing agent, and a first complexing agent; the first complexing agent includes one or more of ethylenediaminetetraacetic acid, ethylenediaminetetraacetic acid salt, diethyltriaminepentaacetic acid, and diethyltriaminepentaacetic acid salt. The second solution and the silver salt solution are mixed and dried under vacuum to obtain silver-coated copper powder; the silver salt solution includes a second complexing agent; the second complexing agent includes one or more of citric acid and citrate.
2. The method according to claim 1, characterized in that, The pH of the first solution is 2.0-3.
0.
3. The method according to claim 1, characterized in that, The corrosion inhibitor includes one or more of the following: thiourea, thiols, imidazoles, quaternary ammonium salts, chromates, nitrites, molybdates, and phosphates. And / or, the dispersant includes one or more of polyvinylpyrrolidone, polyethylene glycol, gelatin, cellulose or its derivatives, and gum arabic; And / or, the reducing agent includes one or more of ascorbic acid or its derivatives, hydrazine hydrate, glucose, and potassium sodium tartrate.
4. The method according to claim 1, characterized in that, The mass ratio of the corrosion inhibitor to the copper powder is (0.01-0.2):1; And / or, the mass ratio of the dispersant to the copper powder is (0.01-0.05):1; And / or, the molar ratio of the reducing agent to the silver in the silver salt solution is (0.1-1):1; And / or, the mass ratio of the first complexing agent to the copper powder is (0.1-0.5):1; And / or, the molar ratio of the second complexing agent to the silver in the silver salt solution is (0.1-2):
1.
5. The method according to claim 1, characterized in that, The copper powder, corrosion inhibitor, and first solution are mixed at 20-40°C. And / or, at 20-40°C, mix the second solution and the silver salt solution.
6. The method according to claim 1, characterized in that, The molar ratio of the copper powder to the silver in the silver salt solution is (1-20):
1.
7. The method according to claim 1, characterized in that, The pH of the silver salt solution is 2-3.
8. The method according to claim 1, characterized in that, The silver salt solution is added to the second solution and mixed. Furthermore, the silver salt solution is added to the second solution over a period of 5-30 minutes.
9. The method according to claim 1, characterized in that, The copper powder has a particle size of 0.5-10 μm.
10. The silver-coated copper powder obtained by the method according to any one of claims 1-9.