Flaky composite copper powder with controllable size and thickness as well as seed induction preparation method and application of flaky composite copper powder

Abstract

The invention discloses flaky composite copper powder with the controllable size and thickness and a seed induction preparation method and application of the flaky composite copper powder, and relates to the technical field of electronic materials.The flaky composite copper powder with the controllable size and thickness is composed of an inner core and an outer shell layer, the inner core is flaky powder, the size is 0.5-2 micrometers, and the outer shell layer is composed of an outer shell layer and an inner shell layer; the inner core is selected from one of silver powder, copper powder, tin powder, aluminum oxide or silicon dioxide powder; the shell is a copper plating layer, and the thickness of the shell can be controlled to be 0.02-2 microns; the shell layer is complete and compact. The preparation method comprises the following steps: S1, pretreating flaky seeds; s2, carrying out surface chemical copper plating on the flaky seeds under an ultrasonic stirring process; and S3, after the reaction is finished, centrifugally separating a product, cleaning and drying to obtain the flaky composite copper powder. According to the seed induction chemical plating method, the morphology and size distribution of the composite copper powder can be accurately controlled by flexibly regulating and controlling the reaction conditions, meanwhile, efficient deposition of copper is achieved within a short time, and the strict requirement for the performance of a copper powder material in the field of electronic materials is met.

Description

Technical Field

[0001] The invention relates to the technical field of electronic materials, and in particular to a flaky composite copper powder with controllable size and thickness, and a seed-induced preparation method and application thereof. Background Art

[0002] The demand for high-performance materials in the core areas of the electronic information industry (PCB, photovoltaic modules, etc.) has surged. Conductive adhesives, as key materials in electronic manufacturing, are widely used in component connection, packaging and repair. Although traditional silver-based conductive adhesives have excellent performance, their high cost restricts their large-scale application. Copper powder is considered an ideal choice for the new generation of conductive fillers because of its low cost and conductivity close to that of silver. The development of its efficient preparation technology has important economic value.

[0003] The performance of conductive adhesives depends critically on the morphology and size of the conductive filler. Two-dimensional sheet fillers have become a research hotspot due to their large contact area and excellent conductivity. Their preparation methods are divided into two categories: "top-down" and "bottom-up". The former obtains two-dimensional copper sheets through physical processing, which is simple and easy to mass produce; but it is easy to cause cold welding problems, making it difficult to control the morphology and sheet diameter, and may introduce impurities that affect purity, making it difficult to meet the needs of high-precision applications.

[0004] Microscale (small, 2018, Vol. 14, p. 3312) reported a method for preparing single-crystalline two-dimensional copper nanosheets using a hydrothermal method. Iodine was used to form an adsorption layer on the substrate surface of the nano-copper crystal, thereby changing the structure of the nano-copper crystal, and a large-size single-crystalline two-dimensional copper nanosheet with a sheet diameter of 30μm was obtained. However, its synthesis process is complicated, and the radial growth of the copper nanosheet cannot be controlled. As a conductive filler, the large sheet diameter leads to poor fluidity of the slurry and is difficult to adapt to a variety of printing methods. Developing a method for preparing flaky composite copper powder with controllable size and thickness through seed-induced chemical plating can achieve efficient copper deposition in a short time. At the same time, the production cost can be further reduced by recycling the plating solution, which is in line with the concept of green environmental protection.

[0005] In view of this, this application is hereby filed. Summary of the invention

[0006] The object of the present invention is to provide a flaky composite copper powder with controllable size and thickness and a seed-induced preparation method and application thereof, so as to solve the problems mentioned in the above background technology.

[0007] An object of the present invention is to provide a flaky composite copper powder with controllable sheet diameter and controllable coating layer thickness.

[0008] Another object of the present invention is to provide a method for preparing flaky composite copper powder with controllable size and thickness.

[0009] Another object of the present invention is to provide an application of a sheet-like composite copper powder with controllable size and thickness as a conductive filler in the preparation of a conductive adhesive.

[0010] To achieve the above object, the technical solution adopted by the present invention is as follows:

[0011] The first aspect of the present invention provides a sheet-like composite copper powder with controllable sheet diameter, controllable coating layer thickness, and complete and dense coating layer, which is composed of a core and a shell layer. The core is a sheet-like powder body with a size of 0.5-2 μm. The core is selected from one of silver powder, copper powder, tin powder, alumina or silica powder, and the thickness is 100-300 nm. The shell is a copper plating layer with a controllable thickness of 0.02-2 μm; the shell layer is complete and dense.

[0012] The technical problem to be solved by the present invention is to achieve precise control of the morphology and size distribution of copper sheets, so as to obtain excellent electrical conductivity.

[0013] To solve the above technical problem, the second aspect of the present invention provides a preparation method of a sheet-like composite copper powder with controllable size and thickness, including the following steps:

[0014] S1. Pretreatment of sheet-like seeds:

[0015] Select a sheet-like powder body with a sheet diameter of 0.5-2 μm as the seed, pickle it for 5-10 minutes, alkali wash it for 5-10 minutes, wash it 3 times with deionized water and ethanol respectively, and then dry it.

[0016] S2. Surface electroless copper plating of sheet-like seeds under ultrasonic stirring process:

[0017] Pre-disperse the sheet-like seeds in the electroless copper plating solution, and then dropwise add formaldehyde solution under ultrasonic stirring for surface electroless copper plating.

[0018] S3. After the reaction is completed, centrifuge and separate the product, wash and dry it to obtain the sheet-like composite copper powder.

[0019] In the above S1, the sheet-like seeds are selected from one of silver powder, copper powder, tin powder, alumina or silica powder, the sheet diameter is 0.5-2 μm, and the thickness is 100-300 nm;

[0020] The shell is a copper plating layer with a thickness of 0.02-2 μm.

[0021] In the above S1, the acid in the pickling is selected from at least one of hydrochloric acid, sulfuric acid, nitric acid, acetic acid solution, and its concentration is 0.1 mol / L; the alkali in the alkali washing comes from at least one of sodium hydroxide, potassium hydroxide, sodium carbonate aqueous solution, and its concentration is 0.1 mol / L.

[0022] In S2, the formulation of the electroless copper plating solution is as follows: copper sulfate pentahydrate, 10 - 20 g / L; sodium potassium tartrate, 30 - 40 g / L; disodium ethylenediaminetetraacetate, 2 - 4 g / L; nickel sulfate, 3 - 5 g / L; sodium hydroxide, 3 - 4 g / L; potassium ferrocyanide, 1 - 3 mg / L; 2,2'-bipyridine, 1 - 2 mg / L.

[0023] In S2, during the pre-dispersion process, the ultrasonic power is 40 - 50 KHz, the temperature is 20 - 30 °C, and the dispersion time is 5 - 10 min. During the electroless plating process, the ultrasonic power is 40 - 50 KHz, the temperature is 30 - 60 °C, and the stirring speed is 100 - 200 rpm.

[0024] In step S2, the addition amount of formaldehyde in the electroless copper plating solution is 20 - 30 mL / L, preferably 25 mL / L.

[0025] In step S2 of the present invention, after adding the formaldehyde solution, when bubbles appear in the solution, it indicates that the electroless copper plating reaction starts. After 10 - 15 min of electroless plating, the particles suspended in the plating solution gradually turn reddish-brown.

[0026] The present invention also provides flaky composite copper powder prepared by the above electroless plating method.

[0027] Furthermore, in the flaky composite copper powder, the flake diameter is 2 - 15 μm, and the thickness is 0.15 - 4 μm.

[0028] The flaky composite copper powder prepared by the present invention forms a dense copper plating layer on the surface of the flaky seeds through electroless plating technology, and flaky composite copper powder with controllable flake diameter and thickness is obtained.

[0029] Furthermore, the present invention also provides an electrically conductive adhesive prepared from the flaky composite copper powder as an electrically conductive filler. The flaky composite copper powder and the organic resin are mixed in proportion, and are uniformly mixed into a slurry through processes such as homogenization, and a flaky composite copper powder electrically conductive copper circuit with excellent electrical conductivity is obtained after coating and curing.

[0030] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0031] In the present invention, the thickness of the copper plating layer of the prepared flaky composite copper powder and the size of the seeds can both be adjusted. The copper plating layer on the surface is evenly distributed, without obvious agglomeration phenomenon, and there is no impurity. By changing the size and quantity of the seeds, copper plating layers with different thicknesses and surface morphologies can be obtained. By performing electroless plating multiple times, the proportion of the core in the flaky composite copper powder can be further reduced to reduce the preparation cost. The ultrasonic stirring process is adopted to effectively solve the agglomeration problem during the electroless plating process, and flaky composite copper powder with excellent morphology and no agglomeration is prepared. Description of the Drawings

[0032] Figure 1 Schematic diagram of the mechanism for preparing flaky composite copper powder according to the present invention;

[0033] Figure 2 SEM morphology diagram of electrolessly deposited flaky composite copper powder prepared in Example 1;

[0034] Figure 3 SEM morphology diagram of electrolessly deposited flaky composite copper powder prepared in Example 2;

[0035] Figure 4 SEM morphology diagram of electrolessly deposited flaky composite copper powder prepared in Example 3;

[0036] Figure 5 SEM morphology diagram of flaky copper powder prepared in Comparative Example 1;

[0037] Figure 6 XRD pattern of electrolessly deposited flaky composite copper powder prepared in Example 1;

[0038] Figure 7 UV-Vis spectrum of electrolessly deposited flaky composite copper powder prepared in Example 1. Detailed implementation manners

[0039] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0040] Please refer to Figure 1-7 :

[0041] Example 1:

[0042] This example discloses a method for preparing flaky composite copper powder with controllable size and thickness, including the following steps:

[0043] First step, pretreatment of flaky seeds:

[0044] Select flaky silver powder with a particle diameter of 0.5 - 2 μm as seeds, stir and soak in 0.1 mol / L sulfuric acid for 5 minutes, stir and soak in 0.1 mol / L sodium hydroxide aqueous solution for 5 minutes, wash with deionized water and ethanol three times each, and then dry.

[0045] Second step, seed-induced electroless plating synthesis of flaky composite copper powder:

[0046] 6 mg of silver nanosheets were pre-dispersed in 100 mL of copper plating solution. During the pre-dispersion process, the ultrasonic power was set at 44 kHz, the temperature was controlled at 20 °C, and the dispersion time was 5 min. During this period, nitrogen gas was continuously introduced into the reaction vessel to maintain an inert atmosphere. The formulation of the electroless copper plating solution was preferably: copper sulfate pentahydrate, 15 g / L; sodium potassium tartrate, 32 g / L; disodium ethylenediaminetetraacetate, 2.5 g / L; nickel sulfate, 3.5 g / L; sodium hydroxide 3.2 g / L; potassium ferrocyanide, 2 mg / L; 2,2'-bipyridine, 1 mg / L.

[0047] After the pre-dispersion was completed, the temperature of the ultrasonic constant temperature device was raised to 40 °C, the stirring speed was 150 rpm, and 2.5 mL of formaldehyde solution (30%) was added dropwise.

[0048] When bubbles appeared in the solution, it indicated that the electroless copper plating reaction had started, and the silver-white particles suspended in the plating solution gradually turned reddish-brown. After 15 min, the plating solution and the generated flaky composite copper powder were quickly transferred to a centrifuge tank for separation.

[0049] Step 3, separating the flaky composite copper powder:

[0050] The centrifugation parameters were set at 3000 - 4000 rpm for 2 - 5 min. After the reddish-brown precipitate at the bottom was separated from the supernatant, it was ultrasonically centrifuged and washed with deionized water again, and the operation was repeated 5 times. Finally, it was washed with ethanol once. The washed product was placed in a shaded and cool place to dry to avoid oxidation of the copper layer, and finally the flaky composite copper powder was collected.

[0051] Its morphology is as Figure 2 shown. Its sheet diameter is 3 - 4 μm, the thickness is 0.3 - 0.5 μm, and the diameter-thickness ratio is 8 - 10.

[0052] Its XRD pattern is as Figure 6 shown. Combining the XRD pattern, it can be seen that the powder has strong diffraction peaks at 43°, 50°, and 74°, which represent the (111), (200), and (220) crystal planes of the copper face-centered cubic structure, respectively, and are consistent with PDF#04 - 0836. Weak diffraction peaks were also observed at 38°, 44°, 64°, and 77°, corresponding to the (111), (200), (220), and (311) crystal planes of the silver face-centered cubic structure, respectively, and are consistent with PDF#87 - 0717, which also confirms that the copper sheet is a silver-copper core-shell structure.

[0053] Its ultraviolet-visible spectrum is as Figure 7As shown, during electroless plating, samples were taken at 0 min, 5 min, 10 min, and 15 min respectively. The silver nanosheets exhibited an absorption peak at 267 nm. After 5 min of electroless plating, an absorption peak of copper appeared at 224 nm, and this absorption peak gradually increased with the prolongation of the electroless plating time. In addition, at 318 nm where there was no significant absorbance originally, the absorbance of copper at this place also increased significantly with the progress of electroless plating, indicating that the silver nanosheets were gradually coated with copper. When the electroless plating reached 15 min, the silver nanosheets were completely covered with a copper layer.

[0054] Example 2:

[0055] This example discloses a method for preparing sheet-shaped composite copper powder with controllable size and thickness, including the following steps:

[0056] The first step, pretreatment of sheet-shaped composite copper powder:

[0057] The sheet-shaped composite copper powder prepared in Example 1 was placed in 0.1 mol / L sulfuric acid and stirred and soaked for 5 min, then placed in 0.1 mol / L sodium hydroxide aqueous solution and stirred and soaked for 5 min, washed 3 times each with deionized water and ethanol, and then dried.

[0058] The second step, seed-induced electroless plating to thicken the sheet-shaped composite copper powder:

[0059] Weigh 6 mg of the pretreated sheet-shaped composite copper powder prepared in Example 1 and pre-disperse it in 100 mL of copper plating solution. During the pre-dispersion process, the ultrasonic power is set to 44 kHz, the temperature is controlled at 20 °C, and the dispersion time is 5 min. During this period, nitrogen gas is continuously introduced into the reaction vessel to maintain an inert atmosphere. The formula of the electroless copper plating solution is: copper sulfate pentahydrate, 15 g / L; sodium potassium tartrate, 32 g / L; disodium ethylenediaminetetraacetate, 2.5 g / L; nickel sulfate, 3.5 g / L; sodium hydroxide 3.2 g / L; potassium ferrocyanide, 2 mg / L; 2,2'-

[0060] bipyridine, 1 mg / L.

[0061] After the pre-dispersion is completed, raise the temperature of the ultrasonic constant temperature device to 40 °C, the stirring speed is 150 rpm, and gradually add 2.5 mL of formaldehyde solution (30%).

[0062] When bubbles are generated in the solution, it indicates that the electroless copper plating reaction has started. After 15 min, quickly transfer the plating solution and the generated sheet-shaped composite copper powder to a centrifuge tank for separation.

[0063] The third step, separation of sheet-shaped composite copper powder:

[0064] The centrifugation parameter is set to 3000 - 4000 rpm for 2 min. After the red - brown precipitate at the bottom is separated from the supernatant, it is ultrasonically centrifuged and washed with deionized water again, and the operation is repeated 5 times. Finally, it is washed once with ethanol. The washed product is dried in a shaded and cool place to avoid oxidation of the copper layer, and finally flaky composite copper powder is collected.

[0065] Its morphology is as Figure 3 shown. The sheet diameter is 5 - 6 μm, the thickness is 1.2 - 1.5 μm, and the diameter - thickness ratio is 4 - 5. By multiple plating, the proportion of silver seeds in the composite copper powder can be significantly reduced, further reducing the preparation cost. Comparing with the size of the flaky composite copper powder in Example 1, it can be found that the diameter - thickness ratio decreases significantly after multiple plating, retaining the advantage of a large contact area of the flaky structure. At the same time, it has a higher tap density under the same mass, which can make the conductive adhesive have better fluidity and adapt to various printing methods.

[0066] Example 3:

[0067] This example discloses a preparation method of flaky composite copper powder with controllable size and thickness, including the following steps:

[0068] The first step, pretreatment of flaky seeds:

[0069] Select flaky silver powder with a sheet diameter of 0.5 - 2 μm as seeds, stir and soak in 0.1 mol / L sulfuric acid for 5 min, stir and soak in 0.1 mol / L sodium hydroxide aqueous solution for 5 min, wash 3 times each with deionized water and ethanol, and then dry.

[0070] The second step, seed - induced electroless plating to synthesize flaky composite copper powder:

[0071] Disperse 25 mg of silver nanosheets in 100 mL of copper plating solution in advance. During the pre - dispersion process, the ultrasonic power is set to 44 kHz, the temperature is controlled at 20 °C, and the dispersion time is 5 min. During this period, nitrogen gas is continuously introduced into the reaction vessel to maintain an inert atmosphere. The preferred formula of the electroless copper plating solution is: copper sulfate pentahydrate, 15 g / L; sodium potassium tartrate, 32 g / L; disodium ethylenediaminetetraacetate, 2.5 g / L; nickel sulfate, 3.5 g / L; sodium hydroxide, 3.2 g / L; potassium ferrocyanide, 2 mg / L; 2,2'-bipyridine, 1 mg / L.

[0072] After the pre - dispersion is completed, raise the temperature of the ultrasonic constant - temperature device to 40 °C, the stirring speed is 150 rpm, and 2.5 mL of formaldehyde solution (30%) is added dropwise.

[0073] When bubbles appear in the solution, it indicates that the electroless copper plating reaction starts, and the silver - white particles suspended in the plating solution gradually turn red - brown. After 15 min, quickly transfer the plating solution and the generated flaky composite copper powder to a centrifuge tank for separation.

[0074] Step 3, separating the flaky composite copper powder:

[0075] The centrifugation parameters are set to 3000 - 4000 rpm and last for 2 - 5 min. After the red - brown precipitate at the bottom is separated from the supernatant, it is ultrasonically centrifuged and washed with deionized water again, and the operation is repeated 5 times. Finally, it is washed with ethanol once. The washed product is dried in a shaded and cool place to avoid oxidation of the copper layer, and finally the flaky composite copper powder is collected.

[0076] Its morphology is as Figure 4 shown. Its flake diameter is 2 - 4 μm, the thickness of the copper layer is 0.16 - 0.33 μm, and the diameter - thickness ratio is 12 - 15. By changing the number of silver seeds, the flake diameter and the thickness of the copper layer of the flaky composite copper powder can be conveniently adjusted.

[0077] Comparative Example 1:

[0078] As a comparison, we list a method for preparing flaky copper powder by the liquid - phase reduction method (Chen Mingwei, Zhu Yongping, Zhang Weigang. Preparation of flaky copper powder by liquid - phase reduction method using PEG600 as template [J]. Chinese Journal of Process Engineering, 2008, (05): 1003 - 1007.).

[0079] Add PEG600 to the aqueous solution of CuSO4·5H2O, stir evenly with a magnetic stirrer, adjust the pH value with diluted sulfuric acid, and raise the temperature to a certain level. The reducing agent NaH2PO2 solution is added dropwise to the above - mentioned solution through a peristaltic pump and reacts for a period of time. The generated copper powder is filtered and separated, washed with water and ethanol, and dried in an 80 °C oven for 1 h. Among them, the concentration of CuSO4 is 0.2 mol / L, the concentration of NaH2PO2 is 0.14 mol / L, the addition amount of the template agent PEG600 is 8 mL, the temperature is 80 °C, and the pH is 0.5.

[0080] The morphology of the flaky copper powder prepared by this method is as Figure 5 shown. The flake diameter is 10 - 40 μm, the thickness is 1.5 - 2.5 μm, and the diameter - thickness ratio of most flaky copper powders is above 10. By comparing with the size of the flaky composite copper powder prepared in Example 1, it can be found that its diameter - thickness ratio has increased significantly, the particle size distribution is wider, and there are a large number of particles with miscellaneous morphologies. It shows that the method of obtaining flaky composite copper powder by electroless plating copper with silver nanosheets as seeds in the present invention overcomes the defect of difficult preparation of copper sheets with a small diameter - thickness ratio. At the same time, the morphology of the flaky composite copper powder can be conveniently controlled through the morphology of the seeds, and the generation of particles with miscellaneous morphologies is reduced.

[0081] Application Example 1:

[0082] The application of a flaky composite copper powder with controllable size and thickness as a conductive filler in the preparation of conductive adhesives includes the following steps:

[0083] The flaky composite copper powder prepared in Example 1 and the organic resin phase are mixed into a conductive adhesive by a homogenization process in mass fractions of 70 - 90% and 30 - 10% in sequence, and after coating, hot pressing and curing are carried out. The procedure is 80°C for 3 min; 200°C for 5 min.

[0084] A four-probe resistance tester is used to measure its initial resistivity and its resistivity after 72 h at 85°C and 85% R.H.

[0085] The properties of the flaky composite copper powder conductive adhesive are as follows:

[0086]

[0087]

[0088] Application Example 2:

[0089] The flaky composite copper powder prepared in Example 2 and the organic resin phase are mixed into a conductive adhesive by a homogenization process in mass fractions of 70 - 90% and 30 - 10% in sequence, and after coating, hot pressing and curing are carried out. The procedure is 80°C for 3 min; 200°C for 5 min.

[0090] A four-probe resistance tester is used to measure its initial resistivity and its resistivity after 72 h at 85°C and 85% RH.

[0091] The properties of the flaky composite copper powder conductive adhesive are as follows:

[0092]

[0093] It should be noted that in this article, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the term "comprising", "including" or any other variant thereof is intended to cover non-exclusive inclusion, so that a process, method, article or device comprising a series of elements not only includes those elements, but also includes other elements not expressly listed, or elements inherent to such process, method, article or device.

[0094] Although the embodiments of the present invention have been shown and described, for those of ordinary skill in the art, it can be understood that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A flaky composite copper powder with controllable size and thickness and a seed-induced preparation method thereof, characterized in that: The following steps are involved: S1. Flake seed pretreatment: The flake powder with a flake diameter of 0.5 to 2 μm was selected as seeds, and was acid-washed for 5 to 10 minutes, alkali-washed for 5 to 10 minutes, washed with deionized water and ethanol three times respectively, and then dried. S2. Surface chemical copper plating of flake seeds under ultrasonic stirring process: The flake seeds are pre-dispersed in a chemical copper plating solution, and then a formaldehyde solution is added dropwise under ultrasonic stirring to perform surface chemical copper plating. S3. After the reaction is completed, the product is separated by centrifugation, and then washed and dried to obtain flaky composite copper powder.

2. The flaky composite copper powder with controllable size and thickness and the seed induction preparation method thereof as claimed in claim 1, characterized in that: In S1, the flake seeds are selected from one of silver powder, copper powder, tin powder, aluminum oxide, and silicon dioxide powder, with a flake diameter of 0.5 to 2 μm and a thickness of 100 to 300 nm; the shell is a copper plating layer with a thickness of 0.02 to 2 μm.

3. The flaky composite copper powder with controllable size and thickness and the seed induction preparation method thereof as claimed in claim 1, characterized in that: In S1, the acid in the pickling is selected from: at least one of hydrochloric acid, sulfuric acid, nitric acid, and acetic acid solution, and the concentration is 0.1 mol / L; the alkali in the alkaline washing comes from: at least one of sodium hydroxide, potassium hydroxide, and sodium carbonate aqueous solution, and the concentration is 0.1 mol / L.

4. The flaky composite copper powder with controllable size and thickness and the seed induction preparation method thereof as claimed in claim 1, characterized in that: In S2, the formula of the chemical copper plating solution is: copper sulfate pentahydrate, 10-20 g / L; sodium tartrate, 30-40 g / L; disodium ethylenediaminetetraacetic acid, 2-4 g / L; nickel sulfate, 3-5 g / L; sodium hydroxide, 3-4 g / L; potassium ferrocyanide, 1-3 mg / L; 2,2'-bipyridine, 1-2 mg / L.

5. The flaky composite copper powder with controllable size and thickness and the seed induction preparation method thereof as claimed in claim 1, characterized in that: In S2, the amount of formaldehyde solution added to the chemical copper plating solution is 20-30 mL / L.

6. The flaky composite copper powder with controllable size and thickness and the seed induction preparation method thereof as claimed in claim 1, characterized in that: In S2, during the pre-dispersion process, the ultrasonic power is 40-50 KHz, the temperature is 20-30°C, and the dispersion time is 5-10 min; during the chemical plating process, the ultrasonic power is 40-50 KHz, the temperature is 30-60°C, and the stirring speed is 100-200 rpm.

7. The flaky composite copper powder is prepared according to the method described in any one of claims 1 to 6.

8. The flaky composite copper powder according to claim 7, characterized in that: The flaky composite copper powder has a diameter of 2 to 15 μm and a thickness of 0.15 to 4 μm.

9. Use of the flaky composite copper powder as claimed in claim 7 or 8 as a conductive filler in preparing a conductive adhesive.

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