Copper-based diamond composite material with high heat conductivity coefficient and preparation method thereof

Abstract

The invention belongs to the technical field of copper-based metal heat conduction materials, and particularly relates to a copper-based diamond high-heat-conductivity-coefficient composite material and a preparation method thereof. The preparation method provided by the invention comprises the following steps: carrying out ultrasonic cleaning on diamond particles, and depositing a metal layer on the surfaces of the diamond particles; diamond particles and a silane coupling agent are mixed, then copper powder and nano silicon carbide are added for stirring and mixing, and a first mixture is obtained; mixing the first mixture with a bonding auxiliary material, and carrying out internal mixing granulation; carrying out injection molding on the granules to obtain a blank; carrying out first degreasing treatment on the blank in a nitric acid steam atmosphere, and then carrying out second degreasing treatment in a hydrogen atmosphere; and then the degreased blank is sintered, and the copper-based diamond composite material with the high heat conductivity coefficient is obtained. The composite material obtained by the method has excellent heat-conducting property, and in addition, the mechanical property of the composite material is better.

Description

Technical Field

[0001] This invention belongs to the technical field of copper-based metal thermal conductive materials, specifically relating to a copper-based diamond high thermal conductivity composite material and its preparation method. Background Art

[0002] In quantum computing chips or semiconductor chip packaging, materials with high thermal conductivity are needed to quickly conduct the heat generated by the chip, preventing heat accumulation that could lead to performance degradation or damage. Large data centers also require heat dissipation components to ensure continuous and efficient data storage and computation, preventing downtime due to overheating. Components such as radio frequency chips in 5G / 6G communication equipment have high power density and generate significant heat, requiring excellent heat dissipation components to ensure the stability and reliability of the equipment during high-frequency, high-power operation, thereby improving communication quality and efficiency. With the rapid proliferation of high-performance data centers, 5G communication, and chip packaging in the electronic information field, the requirements for heat dissipation materials are gradually increasing. The thermal conductivity and performance of existing heat dissipation materials are no longer sufficient to meet the needs of new technologies. Therefore, developing new heat dissipation materials and their preparation methods that are highly efficient, miniaturized, and adaptable to high-performance electronic devices is of great significance for improving the performance of the entire heat dissipation system.

[0003] Because diamond has good thermal conductivity, existing technologies typically use composites of diamond and metal powders to prepare materials with high thermal conductivity in order to solve this problem. Generally, copper and diamond are combined to improve the thermal conductivity of the composite material, but the improvement effect is still limited. Summary of the Invention

[0004] Therefore, the technical problem to be solved by the present invention is to overcome the above-mentioned problems and to provide a copper-based diamond high thermal conductivity composite material and its preparation method.

[0005] A method for preparing a copper-based diamond high thermal conductivity composite material includes the following steps:

[0006] 1) The diamond particles are ultrasonically cleaned, and then a metal layer is deposited on the surface of the diamond particles by magnetron sputtering.

[0007] 2) Diamond particles with a surface-deposited metal layer are mixed with a silane coupling agent, and then copper powder and nano-silicon carbide are added and stirred to obtain the first mixture;

[0008] 3) The first mixture and the binder are mixed and then granulated to obtain granules;

[0009] 4) The granules obtained in step 3) are injection molded to obtain a copper-based composite diamond material blank;

[0010] 5) The blank obtained in step 4) is first degreased in a nitric acid vapor atmosphere, and then degreased in a hydrogen atmosphere; then the degreased blank is sintered to obtain a copper-based diamond high thermal conductivity composite material.

[0011] Preferably, the metal layer is selected from at least one of titanium, tin, and copper.

[0012] The average particle size of the diamond particles mentioned in step 1) is 40-100 μm;

[0013] The thickness of the metal layer is 100-500 nm.

[0014] Preferably, in step 1), the diamond particles are washed with a hydrofluoric acid solution with a concentration of 1-4 wt%.

[0015] Preferably, after ultrasonic cleaning of the diamond particles in step 1), metallic titanium rod-shaped particles are first deposited on the surface of the diamond particles by magnetron sputtering, and then a metallic titanium layer is deposited on the surface of the diamond particles by magnetron sputtering. The metallic titanium rod-shaped particles protrude from the metallic titanium layer and have an average height of 10-20 nm from the metallic titanium layer.

[0016] The method used in this invention to deposit titanium rod-shaped particles and a metal layer on the surface of diamond particles using magnetron sputtering is a conventional method in the field and will not be elaborated or described in detail here. The average height of the titanium rod-shaped particles from the titanium layer refers to the average distance from the highest point of the titanium rod-shaped particles to the surface of the titanium layer.

[0017] Preferably, the amount of silane coupling agent added is 1-3% of the mass of the diamond particles in the surface deposited metal layer;

[0018] The copper powder has an average particle size of 5-30 μm, and the nano-silicon carbide has an average particle size of 30-50 nm.

[0019] Preferably, the volume ratio of copper powder, diamond particles with surface deposited metal layer and nano-silicon carbide is (40-60):(30-50):(1-5);

[0020] The mixing time for diamond particles and silane coupling agent is 2-5 hours, and the mixing time for adding copper powder and nano silicon carbide is 2-5 hours.

[0021] The silane coupling agent is coupling agent KH550.

[0022] Preferably, step 2) further includes the step of adding Ag-based alloy solder, wherein the average particle size of the Ag-based alloy solder is 5-30 μm, and the composition includes silver: 68-75 wt%, copper: 18-28 wt%, and titanium: 3-5 wt%.

[0023] The volume ratio of copper powder, diamond particles with surface deposited metal layer, nano-silicon carbide and Ag-based alloy solder is (40-60):(30-50):(1-5):(1-5);

[0024] The adhesive additive is selected from at least one of polyoxymethylene, high-density polyethylene, ethylene-vinyl acetate copolymer, paraffin wax, stearic acid, and antioxidants. The polyoxymethylene, high-density polyethylene, ethylene-vinyl acetate copolymer, paraffin wax, stearic acid, and antioxidants used in this invention are all conventional materials existing in the art and will not be described in detail here.

[0025] Preferably, the volume ratio of the first mixture to the binder is (50-65):(35-50);

[0026] The mixing temperature is 170-200℃, and the mixing time is 15-45 minutes.

[0027] The adhesive additives, by weight percentage, consist of: 75-90% polyoxymethylene, 1-5% high-density polyethylene, 1-5% ethylene-vinyl acetate copolymer, 1-5% paraffin wax, 1-5% stearic acid, and 0.5-5% antioxidant.

[0028] The antioxidant is benzotriazole.

[0029] Optionally, in step 3), the final feed melt index is controlled at 80-120 g / 10 min.

[0030] Preferably, the injection temperature is 175-200℃, the mold temperature is 50-80℃, and the holding pressure is 80-120MPa;

[0031] The first degreasing temperature is 110-130℃, and the degreasing time is 5-8 hours; the second degreasing temperature is 260-450℃, the heating rate is 0.5-1℃ / min, and the degreasing time is 2-6 hours.

[0032] The sintering process is carried out in two stages. The first stage sintering temperature is 700-950℃ and the holding time is 0.5-2h. The second stage sintering temperature is 950-1080℃ and the holding time is 2-4h. The sintering atmosphere in both stages is nitrogen or argon.

[0033] In this invention, the copper powder can be electrolytic copper powder (purity ≥ 99.9%).

[0034] The present invention also provides a copper-based diamond high thermal conductivity composite material, which is prepared by the preparation method described above.

[0035] The technical solution of this invention has the following advantages:

[0036] 1. The method for preparing the composite material provided by the present invention firstly involves ultrasonically cleaning diamond particles, and then depositing a metal layer on the surface of the diamond particles by magnetron sputtering; mixing the diamond particles with the deposited metal layer with a silane coupling agent, and then adding copper powder and nano-silicon carbide for stirring and mixing to obtain a first mixture; mixing the first mixture with binder additives and then granulating by kneading to obtain granules; injection molding the granules to obtain a copper-based composite diamond material blank; subjecting the blank to a first degreasing treatment under a nitric acid vapor atmosphere, and then a second degreasing treatment under a hydrogen atmosphere; subsequently, sintering the degreased blank to obtain a copper-based diamond high thermal conductivity composite material.

[0037] The inventors discovered in their research that the wettability of copper-based materials and diamond affects the thermal conductivity of composite materials. This invention uses magnetron sputtering to deposit a metal layer on the surface of diamond particles, then mixes the diamond particles with the deposited metal layer with a silane coupling agent. Through the synergistic effect of the metal coating and the silane coupling agent, the wettability of copper-based materials and diamond is effectively improved, allowing the liquid metal to spread better on the diamond surface and synergistically reducing the thermal resistance at the copper-diamond interface. Furthermore, nano-silicon carbide fills the gaps between copper powders, improving feed flowability and sintering density. Titanium can react with diamond at high temperatures to form carbides, effectively enhancing the thermal conductivity and mechanical properties of the composite material. The method combines nitric acid catalytic degreasing with hydrogen reduction thermal degreasing, avoiding the stress cracking problem of traditional solvent degreasing while minimizing carbon residue. The method of this invention yields composite materials with excellent thermal conductivity and improved mechanical properties.

[0038] 2. In the method for preparing the composite material provided by this invention, further, in step 1), after ultrasonically cleaning the diamond particles, metallic titanium rod-shaped particles are first deposited on the surface of the diamond particles by magnetron sputtering, and then a metallic titanium layer is deposited on the surface of the diamond particles by magnetron sputtering. The metallic titanium rod-shaped particles protrude from the metallic titanium layer, and the average height of the particles from the metallic titanium layer is 10-20 nm. This invention, by setting metallic titanium rod-shaped particles on the metallic titanium layer, can increase the contact area between the copper-based material and the diamond, improve its wettability, and is less prone to melting and accumulation at high temperatures, greatly improving the wetting and spreading effect, thereby effectively enhancing the thermal conductivity and mechanical properties of the composite material.

[0039] 3. The method for preparing the composite material provided by the present invention further includes step 2) of adding Ag-based alloy brazing filler metal. By adding a specific Ag-based alloy brazing filler metal, the contact angle between the Ag-based alloy brazing filler metal and diamond at high temperature can reach 26.62°-13.5°. Such a small contact angle greatly facilitates the spread of the alloy brazing filler metal on the diamond surface, thereby effectively improving the wettability of copper-based materials and diamond, giving it excellent thermal conductivity, and also effectively improving the mechanical properties of the composite material. Attached Figure Description

[0040] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly described below. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0041] Figure 1 This is a schematic diagram of the structure of depositing titanium rod-shaped particles and a metallic titanium layer on the surface of diamond particles in Example 3. Detailed Implementation

[0042] The following embodiments are provided to further understand the present invention and are not limited to the preferred embodiments described herein, nor do they constitute a limitation on the scope of protection of the present invention.

[0043] Experimental steps or conditions not specified in the following embodiments of this invention can be implemented according to conventional experimental steps and conditions used in existing literature in this field. Reagents or instruments whose manufacturers are not specified are all commercially available conventional reagents or instruments.

[0044] Example 1

[0045] This embodiment provides a method for preparing a copper-based diamond high thermal conductivity composite material, including the following steps:

[0046] 1) Diamond particles (average particle size 45μm) were ultrasonically cleaned with 2wt% hydrofluoric acid solution, washed with water, and then a titanium layer was deposited on the surface of the diamond particles by magnetron sputtering. The thickness of the titanium layer was 200nm.

[0047] 2) Diamond particles with a surface-deposited titanium metal layer were mixed with 3wt% silane coupling agent KH550 for 3h, and then electrolytic copper powder (average particle size 20μm) and nano-silicon carbide (average particle size 50nm) were added and stirred at room temperature for 3h. The volume ratio of electrolytic copper powder, diamond particles with a surface-deposited titanium metal layer and nano-silicon carbide was 60:35:5 to obtain the first mixture.

[0048] 3) The first mixture and the binder were added to the integrated mixer and granulator for mixing and granulation. The mixing temperature was 190℃ and the mixing time was 35min. The binder was added in three batches to obtain granules. The volume ratio of the first mixture and the binder was 60:40. The composition of the binder by mass percentage was: 89% polyoxymethylene (POM), 5% high-density polyethylene (HDPE), 2% ethylene-vinyl acetate copolymer (EVA), 2% paraffin wax, 1.5% stearic acid (SA), and 0.5% antioxidant benzotriazole.

[0049] 4) The granules obtained in step 3) are injection molded in an injection molding machine at an injection temperature of 190°C, a mold temperature of 55°C, and a holding pressure of 120MPa to obtain a copper-based composite diamond material blank.

[0050] 5) The blank obtained in step 4) is first degreased in a nitric acid vapor atmosphere at a temperature of 110℃ for 5 hours, followed by a second degreased in a hydrogen atmosphere at a temperature of 400℃ at a heating rate of 1℃ / min for 6 hours. The degreased blank is then sintered in an argon atmosphere in two stages: first, it is held at 800℃ for 1 hour, then at 1050℃ for 2 hours, and finally cooled to room temperature in the furnace to obtain a copper-based diamond high thermal conductivity composite material. The thermal conductivity of the copper-based diamond high thermal conductivity composite material is tested to be 620 W / m·K, and its flexural strength is 320 MPa.

[0051] Example 2

[0052] This embodiment provides a method for preparing a copper-based diamond high thermal conductivity composite material, including the following steps:

[0053] 1) Diamond particles (average particle size 60μm) were ultrasonically cleaned with 4wt% hydrofluoric acid solution, washed with water, and then a titanium layer was deposited on the surface of the diamond particles by magnetron sputtering. The thickness of the titanium layer was 150nm.

[0054] 2) Diamond particles with a surface-deposited titanium layer were mixed with 2.5 wt% silane coupling agent KH550 for 3 h. Then, electrolytic copper powder (average particle size 30 μm) and nano-silicon carbide (average particle size 30 nm) were added and stirred at room temperature for 3 h. The volume ratio of electrolytic copper powder, diamond particles with a surface-deposited titanium layer and nano-silicon carbide was 60:35:5 to obtain the first mixture.

[0055] 3) The first mixture and the binder were added to the integrated mixer and granulator for mixing and granulation. The mixing temperature was 185℃ and the mixing time was 45min. The binder was added in three batches to obtain granules. The volume ratio of the first mixture and the binder was 65:35. According to the mass percentage, the composition of the binder was: 89% polyoxymethylene (POM), 5% high-density polyethylene (HDPE), 3% ethylene-vinyl acetate copolymer (EVA), 1% paraffin wax, 1.5% stearic acid (SA) and 0.5% antioxidant benzotriazole.

[0056] 4) The granules obtained in step 3) are injection molded in an injection molding machine at an injection temperature of 190°C, a mold temperature of 65°C, and a holding pressure of 110MPa to obtain a copper-based composite diamond material blank.

[0057] 5) The blank obtained in step 4) is first degreased in a nitric acid vapor atmosphere at 130℃ for 6 hours, followed by a second degreased in a hydrogen atmosphere at 450℃ at a heating rate of 1℃ / min for 4 hours. The degreased blank is then sintered in an argon atmosphere in two stages: first, it is held at 750℃ for 1 hour, then at 1000℃ for 3 hours, and finally cooled to room temperature in the furnace to obtain a copper-based diamond high thermal conductivity composite material. The thermal conductivity of the copper-based diamond high thermal conductivity composite material is tested to be 614 W / m·K, and its flexural strength is 317 MPa.

[0058] Example 3

[0059] This embodiment provides a method for preparing a copper-based diamond high thermal conductivity composite material, including the following steps:

[0060] 1) Diamond particles (average particle size 45μm) were ultrasonically cleaned with 2wt% hydrofluoric acid solution and washed with water. First, metallic titanium rod-shaped particles were deposited on the surface of the diamond particles by magnetron sputtering. Then, a metallic titanium layer was deposited on the surface of the diamond particles by magnetron sputtering. The thickness of the metallic titanium layer was 200nm, and the average height of the metallic titanium rod-shaped particles from the metallic titanium layer was 10nm.

[0061] 2) Diamond particles with a surface-deposited titanium metal layer were mixed with 3wt% silane coupling agent KH550 for 3h, and then electrolytic copper powder (average particle size 20μm) and nano-silicon carbide (average particle size 50nm) were added and stirred at room temperature for 3h. The volume ratio of electrolytic copper powder, diamond particles with a surface-deposited titanium metal layer and nano-silicon carbide was 60:35:5 to obtain the first mixture.

[0062] 3) The first mixture and the binder were added to the integrated mixer and granulator for mixing and granulation. The mixing temperature was 190℃ and the mixing time was 35min. The binder was added in three batches to obtain granules. The volume ratio of the first mixture and the binder was 60:40. The composition of the binder by mass percentage was: 89% polyoxymethylene (POM), 5% high-density polyethylene (HDPE), 2% ethylene-vinyl acetate copolymer (EVA), 2% paraffin wax, 1.5% stearic acid (SA), and 0.5% antioxidant benzotriazole.

[0063] 4) The granules obtained in step 3) are injection molded in an injection molding machine at an injection temperature of 190°C, a mold temperature of 55°C, and a holding pressure of 120MPa to obtain a copper-based composite diamond material blank.

[0064] 5) The blank obtained in step 4) is first degreased in a nitric acid vapor atmosphere at a temperature of 110℃ for 5 hours, followed by a second degreased in a hydrogen atmosphere at a temperature of 400℃ at a heating rate of 1℃ / min for 6 hours. The degreased blank is then sintered in an argon atmosphere in two stages: first, it is held at 800℃ for 1 hour, then at 1050℃ for 2 hours, and finally cooled to room temperature in the furnace to obtain a copper-based diamond high thermal conductivity composite material. The thermal conductivity of the copper-based diamond high thermal conductivity composite material is tested to be 635 W / m·K, and its flexural strength is 332 MPa.

[0065] Example 4

[0066] This embodiment provides a method for preparing a copper-based diamond high thermal conductivity composite material. The difference from Embodiment 3 lies in step 1), where diamond particles (average particle size 45 μm) are ultrasonically cleaned with a 2 wt% hydrofluoric acid solution, followed by water washing. The diamond particles and titanium particles are then mixed, heated to allow the titanium to slightly melt and adhere to the diamond surface, and then a titanium layer is deposited on the diamond particle surface using magnetron sputtering. The titanium layer has a thickness of 200 nm, and the average height of the titanium particles from the titanium layer is 10 nm. The tested copper-based diamond high thermal conductivity composite material exhibits a thermal conductivity of 627 W / m·K and a flexural strength of 329 MPa. Compared to the method in Embodiment 3 that constructs titanium rod-shaped particles, this method suffers from limited improvement in the thermal conductivity and flexural strength of the copper-based diamond composite material because the titanium particles are difficult to uniformly adhere to the diamond particle surface, and the titanium particles partially melt during magnetron sputtering, leading to molten accumulation of titanium on the diamond particle surface.

[0067] Example 5

[0068] This embodiment provides a method for preparing a copper-based diamond high thermal conductivity composite material, including the following steps:

[0069] 1) Diamond particles (average particle size 45μm) were ultrasonically cleaned with 2wt% hydrofluoric acid solution, washed with water, and then a titanium layer was deposited on the surface of the diamond particles by magnetron sputtering. The thickness of the titanium layer was 200nm.

[0070] 2) Diamond particles with a surface-deposited titanium metal layer were mixed with 3wt% silane coupling agent KH550 for 3h. Then, electrolytic copper powder (average particle size 20μm), nano-silicon carbide (average particle size 50nm), and Ag-based alloy solder (Ag-based alloy solder with an average particle size of 20μm and a composition of 72wt% Ag, 25wt% copper, and 3wt% titanium) were added and stirred at room temperature for 3h. The volume ratio of electrolytic copper powder, diamond particles with a surface-deposited titanium metal layer, nano-silicon carbide, and Ag-based alloy solder was 60:35:3:2 to obtain the first mixture.

[0071] 3) The first mixture and the binder were added to the integrated mixer and granulator for mixing and granulation. The mixing temperature was 190℃ and the mixing time was 35min. The binder was added in three batches to obtain granules. The volume ratio of the first mixture and the binder was 60:40. The composition of the binder by mass percentage was: 89% polyoxymethylene (POM), 5% high-density polyethylene (HDPE), 2% ethylene-vinyl acetate copolymer (EVA), 2% paraffin wax, 1.5% stearic acid (SA), and 0.5% antioxidant benzotriazole.

[0072] 4) The granules obtained in step 3) are injection molded in an injection molding machine at an injection temperature of 190°C, a mold temperature of 55°C, and a holding pressure of 120MPa to obtain a copper-based composite diamond material blank.

[0073] 5) The blank obtained in step 4) is first degreased in a nitric acid vapor atmosphere at a temperature of 110℃ for 5 hours, followed by a second degreased in a hydrogen atmosphere at a temperature of 400℃ at a heating rate of 1℃ / min for 6 hours. The degreased blank is then sintered in an argon atmosphere in two stages: first, it is held at 800℃ for 1 hour, then at 1050℃ for 2 hours, and finally cooled to room temperature in the furnace to obtain a copper-based diamond high thermal conductivity composite material. The thermal conductivity of the copper-based diamond high thermal conductivity composite material is tested to be 628 W / m·K, and its flexural strength is 323 MPa.

[0074] Example 6

[0075] This embodiment provides a method for preparing a copper-based diamond high thermal conductivity composite material, including the following steps:

[0076] 1) Diamond particles (average particle size 45μm) were ultrasonically cleaned with 2wt% hydrofluoric acid solution, washed with water, and then a copper layer was deposited on the surface of the diamond particles by magnetron sputtering. The thickness of the copper layer was 200nm.

[0077] 2) Diamond particles with a surface-deposited copper layer were mixed with 1 wt% silane coupling agent KH550 for 5 h. Then, electrolytic copper powder (average particle size 20 μm), nano-silicon carbide (average particle size 50 nm), and Ag-based alloy solder (Ag-based alloy solder has an average particle size of 20 μm and a composition of 72 wt% Ag, 25 wt% copper, and 3 wt% titanium) were added and stirred at room temperature for 5 h. The volume ratio of electrolytic copper powder, diamond particles with a surface-deposited copper layer, nano-silicon carbide, and Ag-based alloy solder was 55:35:5:5 to obtain the first mixture.

[0078] 3) The first mixture and the binder were added to the integrated mixer and granulator for granulation. The mixing temperature was 190℃ and the mixing time was 20 minutes. The binder was added in three batches to obtain granules. The volume ratio of the first mixture and the binder was 60:40. The composition of the binder by mass percentage was: 89% polyoxymethylene (POM), 5% high-density polyethylene (HDPE), 2% ethylene-vinyl acetate copolymer (EVA), 2% paraffin wax, 1.5% stearic acid (SA), and 0.5% antioxidant benzotriazole.

[0079] 4) The granules obtained in step 3) are injection molded in an injection molding machine at an injection temperature of 190°C, a mold temperature of 60°C, and a holding pressure of 120MPa to obtain a copper-based composite diamond material blank.

[0080] 5) The blank obtained in step 4) is first degreased in a nitric acid vapor atmosphere at a temperature of 110℃ for 5 hours, followed by a second degreased in a hydrogen atmosphere at a temperature of 450℃ at a heating rate of 1℃ / min for 6 hours. The degreased blank is then sintered in an argon atmosphere in two stages: first, it is held at 950℃ for 1 hour, then at 1080℃ for 2 hours, and finally cooled to room temperature in the furnace to obtain a copper-based diamond high thermal conductivity composite material. The thermal conductivity of the copper-based diamond high thermal conductivity composite material is tested to be 680 W / m·K, and its flexural strength is 330 MPa.

[0081] Comparative Example 1

[0082] This comparative example provides a method for preparing a copper-based diamond high thermal conductivity composite material. The difference from Example 1 is that in step 2), diamond particles with a surface-deposited titanium layer, electrolytic copper powder (average particle size 20 μm), and nano-silicon carbide (average particle size 50 nm) are mixed at room temperature for 3 hours. The volume ratio of electrolytic copper powder, surface-deposited titanium layer diamond particles, and nano-silicon carbide is 60:35:5, resulting in a first mixture. The thermal conductivity of the copper-based diamond high thermal conductivity composite material was tested to be 610 W / m·K, and its flexural strength was 316 MPa.

[0083] Obviously, those skilled in the art can make other modifications based on the above embodiments, and the obvious modifications therefrom are still within the protection scope of this invention.

Claims

1. A method for preparing a copper-based diamond high thermal conductivity composite material, characterized in that, The steps include: 1) The diamond particles are ultrasonically cleaned, and then a metal layer is deposited on the surface of the diamond particles by magnetron sputtering. 2) Diamond particles with a surface-deposited metal layer are mixed with a silane coupling agent, and then copper powder and nano-silicon carbide are added and stirred to obtain the first mixture; 3) The first mixture and the binder are mixed and then granulated to obtain granules; 4) The granules obtained in step 3) are injection molded to obtain a copper-based composite diamond material blank; 5) The blank obtained in step 4) is first degreased in a nitric acid vapor atmosphere, and then degreased in a hydrogen atmosphere; then the degreased blank is sintered to obtain a copper-based diamond high thermal conductivity composite material.

2. The preparation method according to claim 1, characterized in that, The metal layer is selected from at least one of titanium, tin, and copper. The average particle size of the diamond particles mentioned in step 1) is 40-100 μm; The thickness of the metal layer is 100-500 nm.

3. The preparation method according to claim 1 or 2, characterized in that, In step 1), the diamond particles are washed with a 1-4 wt% hydrofluoric acid solution.

4. The preparation method according to claim 1, characterized in that, After ultrasonic cleaning of the diamond particles in step 1), titanium rod-shaped particles are first deposited on the surface of the diamond particles by magnetron sputtering, and then a titanium layer is deposited on the surface of the diamond particles by magnetron sputtering. The titanium rod-shaped particles protrude from the titanium layer and have an average height of 10-20 nm from the titanium layer.

5. The preparation method according to claim 1, characterized in that, The amount of silane coupling agent added is 1-3% of the mass of the diamond particles deposited on the surface metal layer; The copper powder has an average particle size of 5-30 μm, and the nano-silicon carbide has an average particle size of 30-50 nm.

6. The preparation method according to claim 1, characterized in that, The volume ratio of copper powder, diamond particles with surface-deposited metal layer and nano-silicon carbide is (40-60):(30-50):(1-5); The mixing time for diamond particles and silane coupling agent is 2-5 hours, and the mixing time for adding copper powder and nano silicon carbide is 2-5 hours. The silane coupling agent is coupling agent KH550.

7. The preparation method according to claim 1, characterized in that, Step 2) also includes the step of adding Ag-based alloy solder, the average particle size of which is 5-30 μm, and the composition includes silver: 68-75 wt%, copper: 18-28 wt%, and titanium: 3-5 wt%. The volume ratio of copper powder, diamond particles with surface deposited metal layer, nano-silicon carbide and Ag-based alloy solder is (40-60):(30-50):(1-5):(1-5); The adhesive is selected from at least one of polyoxymethylene, high-density polyethylene, ethylene-vinyl acetate copolymer, paraffin wax, stearic acid, and antioxidants.

8. The preparation method according to claim 7, characterized in that, The volume ratio of the first mixture to the binder is (50-65):(35-50); The mixing temperature is 170-200℃, and the mixing time is 15-45 minutes. The adhesive additives, by weight percentage, consist of: 75-90% polyoxymethylene, 1-5% high-density polyethylene, 1-5% ethylene-vinyl acetate copolymer, 1-5% paraffin wax, 1-5% stearic acid, and 0.5-5% antioxidant. The antioxidant is benzotriazole.

9. The preparation method according to claim 1, characterized in that, The injection temperature is 175-200℃, the mold temperature is 50-80℃, and the holding pressure is 80-120MPa; The first degreasing temperature is 110-130℃, and the degreasing time is 5-8 hours; the second degreasing temperature is 260-450℃, the heating rate is 0.5-1℃ / min, and the degreasing time is 2-6 hours. The sintering process is carried out in two stages. The first stage sintering temperature is 700-950℃ and the holding time is 0.5-2h. The second stage sintering temperature is 950-1080℃ and the holding time is 2-4h. The sintering atmosphere in both stages is nitrogen or argon.

10. A copper-based diamond high thermal conductivity composite material, characterized in that, It is prepared by the preparation method according to any one of claims 1-9.

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