High-compaction flaky copper powder and preparation method thereof

Abstract

The invention provides high-compaction flaky copper powder and a preparation method thereof, and relates to the technical field of copper powder. According to the method, a liquid phase reduction method is combined with a ball milling method, the spheroidic copper powder obtained after liquid phase reduction can be directly used for the ball milling process after being simply concentrated, the flaky copper powder with the tap density not lower than 4.0 g / cm < 3 > is obtained, the process period can be shortened, investment of equipment, chemical reagents and the like can be reduced, obvious economic benefits are achieved, and the method is suitable for industrial production. And the method is more suitable for large-scale production.

Description

Technical Field

[0001] The present invention belongs to the technical field of copper powder, and relates to a high tap density flaky copper powder and a preparation method thereof. Background Art

[0002] Ultrafine copper powder is a metal filler for conductive copper paste and is widely used in the electronic industrial fields such as integrated circuit packaging, flexible printed circuit boards, MLCCs, etc. Flaky copper powder is a kind of ultrafine copper powder and has a larger specific surface area compared with spherical copper powder and dendritic copper powder. The addition of flaky copper powder in conductive paste helps to improve the sintering performance of the paste. Especially the high tap density flaky copper powder with a small diameter-thickness ratio and high crystallinity can achieve excellent electrical conductivity while taking into account the high density and low viscosity of conductive copper paste. Therefore, the preparation of high tap density flaky copper powder has always been the focus of attention in the field of ultrafine copper powder. The preparation methods of flaky copper powder mainly include chemical methods and physical methods. The chemical method uses water-soluble copper salts (such as copper sulfate) as the copper source, and the raw material cost is low, but the size controllability of the obtained flaky copper powder is poor, the diameter-thickness ratio is large, and the tap density of the powder is too low (the tap density generally does not exceed 3.8 g / cm 3 ), which is not suitable for the manufacture of high-end conductive paste. The physical method mainly adopts the ball milling method to prepare flaky copper powder through the plastic deformation of copper. The process method is simple, and the prepared flaky copper powder has the advantages of high tap density and easy control of the diameter-thickness ratio, etc., and is the main method for preparing flaky copper powder, especially high tap density flaky copper powder. However, the physical method needs to use spherical or quasi-spherical copper powder prepared by liquid phase reduction or atomization method as the copper raw material, so the raw material cost is much higher than that of the chemical method. Summary of the Invention

[0003] Preparing quasi-spherical copper powder by chemical liquid phase reduction method first and then using it for the preparation of flaky copper powder helps to reduce the production cost. However, after the quasi-spherical copper powder is synthesized in the liquid phase, it needs to go through multiple processes such as cleaning, surface passivation, drying, and crushing to make dry copper powder before it can be used for the subsequent preparation of flaky copper powder. The whole preparation process has a complex process, takes a long time, and needs to add additives such as surfactants, antioxidants, and dispersion aids multiple times, resulting in a high production cost, many processes, and a long process for flaky copper powder. Therefore, after a large amount of analysis, research, and testing, the applicant has developed a preparation method for high tap density flaky copper powder with a simpler process and lower cost. Based on this, the present invention provides a high tap density flaky copper powder and a preparation method thereof.

[0004] The technical solution of the present invention is as follows:

[0005] A high tap density flaky copper powder, the tap density of the flaky copper powder ≥ 4.0 g / cm 3 , D50 is 4 - 9 μm, the ratio of D90 / D50 ≤ 2.0, the oxygen content ≤ 0.2%, and the carbon content ≤ 0.2%;

[0006] The tapped density is tested by a tapped density tester; the D50 and D90 are tested by a laser particle size analyzer; the oxygen content is tested by an oxygen, nitrogen and hydrogen analyzer; and the carbon content is tested by a carbon and sulfur analyzer.

[0007] Preferably, the aspect ratio of the flaky copper powder is 2-6.

[0008] A method for preparing the high-tapped-density flaky copper powder according to any one of the above technical solutions, the steps comprising:

[0009] S1. Mix a water-soluble copper salt, a surfactant, a pH regulator and deionized water, and stir until uniform, then add a reducing agent for reduction to obtain a first slurry;

[0010] S2. Let the first slurry obtained in step S1 stand until the copper powder settles, remove part of the supernatant, add an antioxidant, and stir evenly to obtain a second slurry;

[0011] S3. Transfer the second slurry obtained in step S2 to a ball mill tank, and perform ball milling in an anaerobic or oxygen-deficient environment to obtain a third slurry, filter, wash, dry and crush to obtain the flaky copper powder.

[0012] Preferably, the water-soluble copper salt in step S1 is selected from one or a combination of two or more of copper sulfate, copper chloride, copper nitrate, copper acetate and copper gluconate.

[0013] Preferably, the surfactant in step S1 is selected from one or a combination of two or more of citrate, sulfamate, tartrate, ethylenediaminetetraacetate, sodium hexametaphosphate and sodium pyrophosphate decahydrate.

[0014] Preferably, the pH regulator in step S1 makes the pH of the reaction system 9-12.

[0015] Preferably, the reducing agent in step S1 is selected from one or a combination of two or more of hydrazine hydrate, ascorbic acid, vitamin C, glucose, dimethylhydrazine, sodium borohydride and formaldehyde.

[0016] Preferably, the concentration of the water-soluble copper salt in step S1 is 20-50 g / L, and the molar ratio of the water-soluble copper salt, the surfactant and the reducing agent is 1:0.01-0.05:1.1-2.

[0017] Preferably, in step S2, the removal of part of the supernatant means that the remaining supernatant volume after removal is 1.5-3 times the volume of the copper powder after settlement.

[0018] Preferably, the weight ratio of the antioxidant in step S2 to the water-soluble copper salt in step S1 is 0.001-0.02:1.

[0019] The beneficial effects of the present invention are as follows:

[0020] (1) The present invention adopts the method of liquid-phase reduction method + ball milling method. First, spherical copper powder is obtained, and then through ball milling, flaky copper powder with a high tap density (≥4.0 g / cm 3 ) and a low diameter-thickness ratio can be obtained.

[0021] (2) In the present invention, the surfactant used in the preparation of spherical copper powder by the liquid-phase reduction method can be directly used as the dispersant for ball milling, avoiding the repeated use of the surfactant in the liquid-phase reduction and ball milling steps in the traditional method, significantly reducing the raw material cost of production; after obtaining the spherical copper powder, there is no need to perform steps such as separation, filtration, cleaning, and drying, and it can directly enter the ball milling process in the form of a dispersion liquid, greatly shortening the preparation process cycle of the flaky copper powder. The preparation cycle can be shortened by 30% or more, and the investment in filtration equipment, cleaning equipment, drying equipment, etc. can be saved. The preparation cost of the flaky copper powder can be reduced by 20% or more. Description of the Drawings

[0022] Figure 1 SEM image of the copper powder in the first slurry obtained in Example 1.

[0023] Figure 2 SEM image of the flaky copper powder obtained in Example 1.

[0024] Figure 3 SEM image of the flaky copper powder obtained in Comparative Example 1.

[0025] Figure 4 SEM image of the copper powder in the first slurry obtained in Example 7.

[0026] Figure 5 SEM image of the flaky copper powder obtained in Example 7. Detailed Embodiments

[0027] The technical solutions of the present invention will be further described and illustrated through the following detailed embodiments.

[0028] On the one hand, the present invention provides a high-tap-density flaky copper powder, the tap density of the flaky copper powder ≥4.0 g / cm 3 , D50 is 4 - 9 μm, the ratio of D90 / D50 ≤2.0, the oxygen content ≤0.2%, and the carbon content ≤0.2%;

[0029] The tap density is tested by a tap density meter. Further, the tap density of the flaky copper powder ≥4.2 g / cm 3 ; D50 and D90 are tested by a laser particle size analyzer; the oxygen content is tested by an oxygen-nitrogen-hydrogen analyzer; the carbon content is tested by a carbon-sulfur analyzer.

[0030] The high tap density flaky copper powder of the present invention has a relatively high tap density, and the particle size distribution is relatively concentrated.

[0031] In some embodiments, the aspect ratio of the flaky copper powder is 2 - 6. In the present invention, the aspect ratio refers to the ratio of the average bottom diameter to the average thickness of the flaky copper powder. The above aspect ratio can be tested according to the method of Example 1 of Chinese Patent CN103196802B. Further, the aspect ratio of the flaky copper powder of the present invention can be 2.5 - 5.5.

[0032] On the other hand, the present invention also provides a method for preparing the high tap density flaky copper powder according to any one of the above technical solutions, and the steps include:

[0033] S1. Mix a water-soluble copper salt, a surfactant, a pH regulator and deionized water and stir until uniform, then add a reducing agent for reduction to obtain a first slurry;

[0034] S2. Let the first slurry obtained in step S1 stand until the copper powder settles, remove part of the supernatant, add an antioxidant, and stir evenly to obtain a second slurry;

[0035] S3. Transfer the second slurry of step S2 to a ball mill tank, and perform ball milling in an anaerobic or oxygen-deficient environment to obtain a third slurry, filter, wash, dry and crush to obtain flaky copper powder.

[0036] The present invention uses a method of liquid-phase reduction method + ball milling method to prepare flaky copper powder with high tap density. The copper salt is converted into spherical-like copper powder under the action of a surfactant and a reducing agent. The spherical-like copper powder dispersion is directly ball-milled and converted into high-tap-density flaky copper powder. There is no need for steps such as separating, drying and crushing the spherical-like copper powder in the middle, which can greatly save the preparation process cycle of the high-tap-density flaky copper powder, and also reduce the dosage of auxiliaries such as dispersants, and reduce the investment in filtration equipment, drying equipment, etc., and reduce the production cost of the flaky copper powder.

[0037] In some embodiments, the water-soluble copper salt in step S1 is selected from one or a combination of two or more of copper sulfate, copper chloride, copper nitrate, copper acetate and copper gluconate. The present invention uses a water-soluble copper salt as the copper source without special limitation. Further, the water-soluble copper salt can be copper sulfate or copper sulfate pentahydrate.

[0038] In some embodiments, the surfactant in step S1 is selected from one or a combination of two or more of citrate, sulfamate, tartrate, ethylenediaminetetraacetate, sodium hexametaphosphate, and sodium pyrophosphate decahydrate. For the liquid-phase reduction method of copper source, different surfactants will obtain copper powders with different shapes, which can be flaky copper powders or spherical-like copper powders. If the directly obtained product after liquid-phase reduction is flaky copper powder, after ball milling, the aspect ratio of the obtained flaky copper powder will be larger and the tapped density will be lower. By using the above-mentioned surfactant in combination with the process method of step S1 of the present invention, spherical-like copper powder can be obtained, and after the ball milling process, flaky copper powder with a lower aspect ratio can be obtained, and it has a higher tapped density (≥4.0 g / cm 3 ³). Specifically, the citrate can be sodium citrate or potassium citrate, the sulfamate can be sodium sulfamate, the tartrate can be sodium tartrate or potassium tartrate, and the ethylenediaminetetraacetate can be disodium ethylenediaminetetraacetate.

[0039] In some embodiments, the pH regulator in step S1 makes the pH of the reaction system 9-12. By way of example, the pH regulator can be one or a combination of two or more of sodium hydroxide, sodium carbonate, potassium hydroxide, potassium carbonate, and ammonia water. Preferably, the pH regulator is NaOH or sodium carbonate.

[0040] In some embodiments, the reducing agent in step S1 is selected from one or a combination of two or more of hydrazine hydrate, ascorbic acid, vitamin C, glucose, dimethylhydrazine, sodium borohydride, and formaldehyde. The reduction temperature for adding the reducing agent for reduction in step S1 can be 70-100 °C, and the time can be 1-5 hours. There is no particular limitation on the stirring speed during reduction, and it can be 200-600 rpm.

[0041] In some embodiments, the concentration of the water-soluble copper salt in step S1 is 20 - 50 g / L, and the molar ratio of the water-soluble copper salt, the surfactant, and the reducing agent is 1:0.01 - 0.05:1.1 - 2. In the present invention, the concentration of the water-soluble copper salt can be any value among 20 g / L, 25 g / L, 30 g / L, 35 g / L, 40 g / L, 45 g / L, 50 g / L, etc. The molar ratio of the water-soluble copper salt, the surfactant, and the reducing agent can be any value among 1:0.01:1.1, 1:0.02:1.2, 1:0.02:1.5, 1:0.02:1.8, 1:0.03:1.1, 1:0.05:1.1, 1:0.01:1.3, 1:0.01:1.4, 1:0.01:1.5, 1:0.01:1.6, 1:0.01:1.8, 1:0.01:2, 1:0.03:1.3, 1:0.03:1.4, 1:0.03:1.5, 1:0.03:1.6, 1:0.03:1.8, 1:0.03:2, 1:0.05:1.3, 1:0.05:1.4, 1:0.05:1.5, 1:0.05:1.6, 1:0.05:1.8, 1:0.05:2, etc.

[0042] In some embodiments, the removal of part of the supernatant in step S2 means that the volume of the remaining supernatant after removal is 1.5 - 3 times the volume of the copper powder after sedimentation. Since the density of the obtained spherical copper powder is much greater than that of water and it is micron-sized, the first slurry is prone to sedimentation and aggregation when standing still. The upper part of the first slurry after the spherical copper powder has sedimented is the supernatant that contains no or very few spherical copper powders. Removing part of the supernatant increases the concentration of the spherical copper powder in the slurry, which is equivalent to concentrating the dispersion of the spherical copper powder and is beneficial to the subsequent ball milling process. Since the dispersion still contains a certain amount of surfactant, it can be used as a dispersion aid in the ball milling process, and there is no need to add a dispersion aid during the ball milling stage, which not only shortens the process flow but also reduces the reaction raw materials, thereby reducing the preparation cost of the flaky copper powder. For example, the removal of part of the supernatant in step S2 means that the volume of the remaining supernatant after removal is any value among 1.5 times, 1.8 times, 2 times, 2.2 times, 2.5 times, 2.7 times, 2.8 times, and 3 times the volume of the copper powder after sedimentation. For instance, when the spherical copper powder in the first slurry has sedimented, if the volume of the first slurry is 100 ml, the packed volume of the spherical copper powder after sedimentation is 10 ml, and the volume of the supernatant is 90 ml, then the volume of the remaining supernatant after removing the supernatant can be 15 ml, 20 ml, 25 ml, and 30 ml, and the removed volumes of the supernatant are 75 ml, 70 ml, 65 ml, and 60 ml respectively, and so on.

[0043] In some embodiments, the weight ratio of the antioxidant in step S2 to the water-soluble copper salt in step S1 is 0.001-0.02:1. For example, the weight ratio of the antioxidant to the water-soluble copper salt can be any value among 0.001:1, 0.002:1, 0.003:1, 0.005:1, 0.006:1, 0.008:1, 0.01:1, 0.012:1, 0.015:1, 0.017:1, 0.018:1, 0.02:1, etc. In the present invention, the antioxidant is not particularly limited, and a water-soluble antioxidant is preferably used, such as benzotriazole, benzodithiophene, benzimidazole, etc. The activity of the spherical copper powder is relatively high and it is easily oxidized by air. Adding an antioxidant in the present invention can prevent the obtained spherical copper powder from being oxidized and affecting its performance.

[0044] For the ball milling process of the above step S3, the material of the ball milling beads used for ball milling can be corundum, manganese steel, zirconia, silicon carbide, etc., the diameter range of the ball milling beads can be 0.5-10 mm, and the weight ratio of the added ball milling beads to the water-soluble copper salt added in step S1 can be 5-20:1. The rotation speed of the ball milling can be controlled within 50-170 rpm, and the ball milling time can be controlled within 1-8 h.

[0045] The technical solutions of the present invention will be further described and illustrated according to the following examples. Unless otherwise specified, the parts mentioned in the following examples are parts by weight.

[0046] Example 1

[0047] A copper sulfate solution with a concentration of 40 g / L was prepared in a reaction kettle, sodium citrate was added and stirred evenly, the pH of the reaction solution was adjusted to 10.5 with sodium hydroxide under stirring, and the reducing agent ascorbic acid was added to the reaction kettle. The molar ratio of copper sulfate, sodium citrate and ascorbic acid was 1:0.02:1.2, and the temperature was raised to 90 °C and reacted for 3 h to obtain a first slurry. The SEM picture of the copper powder in the first slurry is as shown in the appendix Figure 1 and has an obvious spherical structure.

[0048] The above first slurry was stopped from stirring and allowed to stand for 2 h. The copper powder completely settled, the upper layer was the supernatant, and the lower layer was the settled copper powder. Part of the supernatant was removed, and the volume of the remaining supernatant was 1.5 times the volume of the deposited copper powder. Antioxidant benzotriazole was added (the addition amount was 0.5% of the weight of copper sulfate), and stirred for 15 min to obtain a second slurry.

[0049] Transfer the above-mentioned second slurry to a ball mill tank, add corundum ball mill beads with a diameter of 0.5 mm (the weight ratio of ball mill beads to copper sulfate is 12:1), purge with nitrogen for 5 min to remove oxygen, and ball mill at a speed of 50 rpm for 4 h to obtain a flaky third slurry. Let the third slurry stand for sedimentation, filter by suction, wash 3 times with deionized water, dry at 60 °C for 8 h, and grind to obtain flaky copper powder. The SEM image of the flaky copper powder is as shown in Figure 2 shown, which has a flaky structure and is relatively closely packed. The D10 particle size of the flaky copper powder measured by a laser particle size analyzer is 3.2 μm, the D50 particle size is 5.5 μm, and the D90 particle size is 9.5 μm. The tapped density of the flaky copper powder measured by a tapped density analyzer is 4.6 g / cm 3 . The oxygen content of the flaky copper powder measured by an oxygen-nitrogen-hydrogen analyzer is 0.19%, and the carbon content of the flaky copper powder measured by a carbon-sulfur analyzer is 0.05%.

[0050] Comparative Example 1

[0051] Let the first slurry of Example 1 stand for sedimentation, filter by suction to remove the supernatant, wash the collected copper powder 3 times with deionized water, add the filter cake obtained after suction filtration to a solution of 20 mg / L benzotriazole, stir and disperse for 60 min, filter the obtained copper powder dispersion by suction again, and wash the filter cake obtained after washing 3 times with deionized water and suction filtration 3 times, dry at 60 °C for 6 h, and grind to obtain spherical copper powder. Add spherical copper powder, grinding aid sodium citrate (the addition amount is 2% of the weight of spherical copper powder), antioxidant benzotriazole (the addition amount is 0.5% of the weight of spherical copper powder), and corundum ball mill beads with a diameter of 0.5 mm (the weight ratio of ball mill beads to spherical copper powder is 12:1), purge with nitrogen for 5 min to remove oxygen, and ball mill at a speed of 50 rpm for 4 h to obtain a reaction slurry of flaky copper powder. Let the reaction slurry of flaky copper powder stand for sedimentation, filter by suction, wash 3 times with deionized water, dry at 60 °C for 8 h, and grind to obtain flaky copper powder. The SEM image of the flaky copper powder is as shown in Figure 3 shown, which has a flaky structure. The measured D10 particle size is 3.0 μm, the D50 particle size is 5.8 μm, the D90 particle size is 9.2 μm, and the tapped density is 4.5 g / cm 3 , the oxygen content is 0.20%, and the carbon content is 0.08%.

[0052] Therefore, the properties of the flaky copper powder obtained in Example 1 and Comparative Example 1 are basically similar. However, compared with Comparative Example 1, Example 1 omits multiple steps such as dispersion, washing, suction filtration, and drying, which can save more than 30% of the process cycle, and also saves equipment investment such as dispersion equipment, washing equipment, suction filtration equipment, and drying equipment, as well as chemical raw material inputs such as dispersion aids and antioxidants, and can reduce production costs by more than 20%.

[0053] Example 2

[0054] The difference between this example and Example 1 is that in Example 1, the molar ratio of copper sulfate, sodium citrate, and ascorbic acid is adjusted from 1:0.02:1.2 to 1:0.05:1.2. The remaining steps remain unchanged.

[0055] Example 3

[0056] The difference between this example and Example 1 is that in Example 1, the molar ratio of copper sulfate, sodium citrate, and ascorbic acid is adjusted from 1:0.02:1.2 to 1:0.04:1.2. The remaining steps remain unchanged.

[0057] Example 4

[0058] The difference between this example and Example 3 is that in Example 3, the molar ratio of copper sulfate, sodium citrate, and ascorbic acid is adjusted from 1:0.04:1.2 to 1:0.04:1.6. The remaining steps remain unchanged.

[0059] Example 5

[0060] The difference between this example and Example 3 is that in Example 3, the molar ratio of copper sulfate, sodium citrate, and ascorbic acid is adjusted from 1:0.04:1.2 to 1:0.04:2. The remaining steps remain unchanged.

[0061] Example 6

[0062] The difference between this example and Example 4 is that in Example 4, the molar ratio of copper sulfate, sodium citrate, and ascorbic acid is adjusted from 1:0.04:1.6 to 1:0.05:1.6. The remaining steps remain unchanged.

[0063] Example 7

[0064] Prepare a copper acetate solution with a concentration of 30 g / L in a reaction kettle, add sodium tartrate and stir evenly. While stirring, adjust the pH of the reaction solution to 9.5 with sodium carbonate. Add the reducing agent ascorbic acid to the reaction kettle. The molar ratio of copper acetate, sodium tartrate, and ascorbic acid is 1:0.03:1.5. Heat up to 80 °C and react for 4 h to obtain the first slurry. The SEM image of the copper powder in the first slurry is as shown in the appendix Figure 4 and has an obvious spherical-like structure.

[0065] Stop stirring the above first slurry and let it stand for 2 h. The copper powder completely settles. The upper layer is the supernatant and the lower layer is the settled copper powder. Remove part of the supernatant, and the volume of the remaining supernatant is 3 times the volume of the deposited copper powder. Add the antioxidant benzotriazole (the addition amount is 0.2% of the weight of copper sulfate) and stir for 12 min to obtain the second slurry.

[0066] Transfer the above-mentioned second slurry to a ball mill tank, add corundum ball mill beads with a diameter of 2 mm (the weight ratio of ball mill beads to copper sulfate is 20:1), purge with nitrogen for 5 min to remove oxygen, and ball mill at a rotation speed of 50 rpm for 5 h to obtain a flaky third slurry. Let the third slurry stand for sedimentation and then filter it by suction. Wash it 3 times with deionized water, dry it at 60 °C for 8 h, and grind it to obtain flaky copper powder. The SEM image of the flaky copper powder is shown in Figure 5 the appendix.

[0067] The performance test results of the flaky copper powder obtained in Examples 1-7 are shown in Table 1 below.

[0068] Table 1

[0069]

[0070]

[0071] From the data results in Table 1 above, it can be seen that the preparation method of the present invention obtains a dispersion of spherical-like copper powder through the liquid-phase reduction method. After the dispersion is concentrated, the ball milling process is directly carried out, and flaky copper powder with a high tap density can be obtained. The preparation process is simple. Compared with the existing method of first preparing spherical-like copper powder and then preparing flaky copper powder, the process cycle is shortened by more than 30%, and the preparation composition of the flaky copper powder is reduced by more than 20%.

[0072] As described above, the basic principles, main features, and advantages of the present invention have been shown and described. Those skilled in the art should understand that the present invention is not limited by the above-mentioned embodiments. The above-mentioned embodiments are only preferred embodiments of the present invention, and the scope of implementation of the present invention cannot be limited thereby. That is, equivalent changes and modifications made according to the scope of the present invention patent and the content of the specification should still fall within the scope covered by the present invention. The scope of protection required by the present invention is defined by the appended claims and their equivalents.

Claims

1. A high-compacted flaky copper powder, characterized in that: The tap density of the flaky copper powder is ≥4.0 g / cm 3 , D50 is 4-9μm, D90 / D50 ratio ≤2.0, oxygen content ≤0.2%, carbon content ≤0.2%; The tap density is tested by a tap density meter; the D50 and D90 are tested by a laser particle size analyzer; the oxygen content is tested by an oxygen, nitrogen and hydrogen analyzer; and the carbon content is tested by a carbon and sulfur analyzer.

2. The high-tapped flaky copper powder according to claim 1, characterized in that: The diameter-to-thickness ratio of the flaky copper powder is 2-6.

3. A method for preparing the high-tapped flaky copper powder according to claim 1 or 2, characterized in that the steps include: S1, mixing a water-soluble copper salt, a surfactant, a pH regulator and deionized water and stirring until uniform, adding a reducing agent for reduction to obtain a first slurry; S2, allowing the first slurry described in step S1 to stand until the copper powder settles, removing part of the supernatant, adding an antioxidant, and stirring evenly to obtain a second slurry; S3, transferring the second slurry described in step S2 to a ball milling tank, ball milling in an oxygen-free or oxygen-deficient environment to obtain a third slurry, filtering, washing, drying, and crushing to obtain the flaky copper powder.

4. The method for preparing high-tapped flaky copper powder according to claim 3, characterized in that: The water-soluble copper salt in step S1 is selected from one or a combination of two or more of copper sulfate, copper chloride, copper nitrate, copper acetate and copper gluconate.

5. The method for preparing high-tapped flaky copper powder according to claim 3, characterized in that: The surfactant in step S1 is selected from one or a combination of two or more of citrate, aminosulfonate, tartrate, ethylenediaminetetraacetate, sodium hexametaphosphate and sodium pyrophosphate decahydrate.

6. The method for preparing high-compacted flaky copper powder according to claim 3, characterized in that: The pH regulator in step S1 makes the pH of the reaction system be 9-12.

7. The method for preparing high-tapped flaky copper powder according to claim 3, characterized in that: The reducing agent in step S1 is selected from one or a combination of two or more of hydrazine hydrate, ascorbic acid, vitamin C, glucose, dimethylhydrazine, sodium borohydride and formaldehyde.

8. The method for preparing high-tapped flaky copper powder according to claim 3, characterized in that: The concentration of the water-soluble copper salt in step S1 is 20-50 g / L, and the molar ratio of the water-soluble copper salt, the surfactant and the reducing agent is 1:0.01-0.05:1.1-2.

9. The method for preparing high-tapped flaky copper powder according to claim 3, characterized in that: In step S2, the removal of part of the supernatant is performed so that the volume of the remaining supernatant after the removal is 1.5-3 times the volume of the copper powder after sedimentation.

10. The method for preparing high-tapped flaky copper powder according to claim 3, characterized in that: The weight ratio of the antioxidant in step S2 to the water-soluble copper salt in step S1 is 0.001-0.02:1.

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