Preparation method of diamond-copper composite material with discrete transition layer

Abstract

The invention provides a preparation method of a diamond-copper composite material with a discrete transition layer, which comprises the following steps: uniformly mixing pretreated diamond particles with tungsten powder, putting the mixture into an alumina crucible, and uniformly covering the mixture with mixed salt of NaCl and KCl; putting the alumina crucible filled with the material into a tubular furnace, introducing argon to remove air, and creating a reducing atmosphere; the tubular furnace is heated, the tungsten powder reacts with the diamond particles, and the diamond particles with the surfaces plated with discrete tungsten carbide transition layers are obtained; diamond particles with the surfaces plated with discrete tungsten carbide transition layers are dispersed in copper sulfate electroplating liquid, electro-deposition is carried out through pulse current, the diamond-copper composite material with the discrete transition layers is obtained, the discrete structure can improve the interface wettability and enhance the interface bonding strength, insulation gaps can be formed through non-plated areas, and therefore the bonding strength of the diamond-copper composite material is improved. Therefore, the hole defect of the copper plating layer is reduced, and the density of the material is effectively improved.

Description

Technical Field

[0001] This invention belongs to the field of metal matrix composite technology, specifically relating to a method for preparing a diamond copper composite material with a discrete transition layer. Background Technology

[0002] As microelectronic devices continue to evolve towards miniaturization, integration, and multifunctionality, their power density is increasing dramatically. This generates a significant amount of heat, severely impacting equipment efficiency and lifespan. Traditional metal-based heat dissipation materials, such as copper and aluminum, no longer meet the requirements of next-generation chip packaging due to their thermal conductivity and coefficient of thermal expansion.

[0003] Diamond-copper composites have become a research hotspot in the field of electronic packaging due to their excellent thermal management properties. The demand for their application in scenarios such as 5G base stations, artificial intelligence chips, and high-power lasers is increasing year by year. In the aerospace field, the lightweight properties and extreme temperature resistance of diamond-copper composites make them an ideal choice for satellite thermal control systems and aircraft engine heat dissipation components. However, their large-scale production still faces bottlenecks such as complex processes and high costs, which restricts their widespread adoption in price-sensitive fields such as consumer electronics.

[0004] Diamond possesses the highest thermal conductivity and a very low coefficient of thermal expansion among all known natural materials at room temperature, making it an ideal filler material for heat sinks. Its phonon thermal conductivity complements that of copper, which has excellent electrical conductivity, making it a mainstream matrix material in electronic packaging. The combination of these two materials allows for synergistic performance optimization, with thermal conductivity 2-3 times higher than pure copper. By adjusting the diamond content, the coefficient of thermal expansion of the composite material can be precisely controlled to meet the matching requirements of different chip packages. However, the poor interfacial wettability (wetting angle > 140°) and chemical incompatibility between diamond and copper result in interfacial thermal resistance accounting for over 60% of the total thermal resistance of the composite material, becoming a key factor limiting its performance improvement.

[0005] Current methods for preparing diamond-copper composites mainly include vacuum hot pressing, melt infiltration, and spark plasma sintering. However, these traditional methods suffer from high energy consumption and low production efficiency. In recent years, electrochemical deposition technology for preparing diamond-copper has attracted much attention due to its ability to achieve low-temperature large-scale preparation. However, diamond-copper composites prepared by electrochemical deposition have poor thermal shock resistance. During thermal cycling tests, the thermal expansion mismatch between diamond and copper leads to the propagation of interfacial microcracks, resulting in surface detachment and a thermal conductivity decay rate as high as 30%.

[0006] To improve the wettability and bonding between diamond and the copper substrate, a continuous tungsten carbide layer is typically deposited on the diamond surface using electroless plating or magnetron sputtering. However, the conductivity of the plating layer makes the diamond particle surface an electrodeposition site. During electrodeposition, the copper plating layer not only grows from the cathode surface upwards but also deposits directly from the tungsten carbide coating surface. This multidirectional deposition results in the copper substrate growing simultaneously from different directions. When copper layers with different growth directions meet between particles, differences in deposition rate or orientation can easily form closed pores, disrupting the uniform deposition of copper ions during electrodeposition. This leads to porosity defects in the copper plating layer, a decrease in material density, and a significant reduction in the thermal conductivity of the composite material. Summary of the Invention

[0007] Based on this, the present invention provides a method for preparing diamond-copper composite material with discrete transition layers, which aims to solve the problem in the prior art where a continuous tungsten carbide layer is deposited on the diamond surface by chemical plating or magnetron sputtering. During the electrodeposition process, the copper plating layer grows disorderly, forming pore defects, which leads to a decrease in material density and thermal conductivity.

[0008] A first aspect of this invention provides a method for preparing a diamond-copper composite material with a discrete transition layer, applicable to an electrodeposition apparatus in which the anode is a phosphor bronze plate and the cathode is a titanium sheet or a copper-plated substrate, comprising the following steps: The pretreated diamond particles were mixed evenly with tungsten powder, the mixture was placed into an alumina crucible, and a mixture of NaCl and KCl was evenly covered on the mixture. Place the alumina crucible containing the material into a tube furnace and introduce argon gas to purge air and create a reducing atmosphere; The tube furnace is heated to react tungsten powder with diamond particles to obtain diamond particles with a discrete tungsten carbide transition layer coated on the surface. Diamond particles coated with a discrete tungsten carbide transition layer were dispersed in a copper sulfate electroplating solution and electrodeposited using a pulsed current to obtain a diamond-copper composite material with a discrete transition layer.

[0009] Furthermore, the average particle size of the tungsten powder is 3μm~40μm.

[0010] Furthermore, the molar ratio of pretreated diamond particles to tungsten powder is 10~20:1.

[0011] Furthermore, in the step of heating the tube furnace to react the tungsten powder with the diamond particles, the temperature of the tube furnace is raised to 1050°C and held for 10 to 60 minutes.

[0012] Furthermore, the diamond particles have a particle size of 50μm to 300μm.

[0013] Furthermore, the surface is coated with a discrete tungsten carbide transition layer with a coverage of 30% to 70%.

[0014] Furthermore, the step of dispersing diamond particles coated with a discrete tungsten carbide transition layer in a copper sulfate electroplating solution and performing electrodeposition using a pulsed current to obtain a diamond-copper composite material with a discrete transition layer includes: Add copper sulfate electroplating solution to the electroplating tank, then add diamond particles with a discrete tungsten carbide transition layer on the surface, and stir magnetically until uniform. The copper sulfate electroplating solution is composed of 120 g / L copper sulfate, 60 g / L sulfuric acid and 50 mg / L chloride ions. The electrodeposition apparatus, which includes a cathode and an anode, is placed horizontally into the electroplating tank. Add the pre-mixed additive to the electroplating tank and stir it thoroughly with magnetic force. The pre-mixed additive consists of 10 ml / L sodium dithiodipropane sulfonate and 5 ml / L polyethylene glycol. The additive is replenished every 12 hours. A pulsed current is applied to maintain a constant current density; By controlling the stirring rate and stirring intermittently, diamond particles with a discrete tungsten carbide transition layer deposited on the surface are allowed to naturally settle onto the cathode surface under gravity and participate in copper substrate electrodeposition. The cathode substrate was removed by rinsing with deionized water to obtain a diamond-copper composite material with a discrete transition layer.

[0015] Furthermore, in the step of electrodeposition using pulsed current, the electrodeposition temperature is 50°C, the forward current density of the pulsed current is 1A / dm²~6A / dm², the reverse current density is 1~4 times the forward current density, and the forward-reverse time ratio within one cycle of the pulsed current is 20:1.

[0016] Furthermore, the amount of diamond particles with a discrete tungsten carbide transition layer on the surface added to the copper sulfate electroplating solution is 2 g / L to 10 g / L.

[0017] A second aspect of the present invention provides a diamond-copper composite material with a discrete transition layer, which is prepared by the above-described method for preparing a diamond-copper composite material with a discrete transition layer.

[0018] Compared with the prior art, implementing the present invention has the following beneficial effects: By providing an electrodeposition apparatus with a phosphor bronze plate as the anode and a titanium sheet or a copper-plated substrate as the cathode, diamond particles with a discrete tungsten carbide transition layer are dispersed in a copper sulfate electrolyte and electrodeposited using a pulsed current to obtain a diamond-copper composite material with a discrete transition layer. Specifically, the pretreated diamond particles are uniformly mixed with tungsten powder, the mixture is placed in an alumina crucible, and a mixed salt of NaCl and KCl is uniformly covered on the mixture. The alumina crucible containing the material is placed in a tube furnace, and argon gas is introduced to purge air and create a reducing atmosphere. The tube furnace is heated to allow the tungsten powder to react with the diamond particles, resulting in diamond particles with a discrete tungsten carbide transition layer. This discrete structure can improve interfacial wettability and enhance interfacial bonding strength, and can also form insulating gaps through unplated areas to inhibit the connection of conductive networks, thereby reducing the porosity defects in the copper plating layer. Ultimately, this can effectively improve the density and thermal conductivity of the diamond-copper composite material. Attached Figure Description

[0019] Figure 1 A flowchart illustrating a method for preparing a diamond-copper composite material with a discrete transition layer, provided by the present invention; Figure 2 This is a scanning electron microscope image of diamond particles with a discrete tungsten carbide transition layer coated on their surface, as shown in Embodiment 1 of the present invention. Figure 3 The X-ray diffraction pattern of diamond particles with a discrete tungsten carbide transition layer on their surface, as shown in Embodiment 1 of the present invention; Figure 4 This is a scanning electron microscope image of the diamond-copper composite material with a discrete transition layer in Embodiment 1 of the present invention; Figure 5 This is a cross-sectional scanning electron microscope image of the diamond-copper composite material with a discrete transition layer in Embodiment 1 of the present invention; Figure 6 This is a scanning electron microscope image of the diamond-copper composite material with a discrete transition layer in Embodiment 2 of the present invention; Figure 7 This is a scanning electron microscope image of the diamond-copper composite material with a continuous transition layer in Comparative Example 1 of the present invention.

[0020] The following detailed embodiments will be further described in conjunction with the above-mentioned accompanying drawings. Detailed Implementation

[0021] To facilitate understanding of the present invention, a more complete description will be given below with reference to the accompanying drawings. Several embodiments of the invention are illustrated in the drawings. However, the invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.

[0022] It should be noted that when a component is said to be "fixed to" another component, it can be directly on the other component or there may be an intervening component. When a component is said to be "connected to" another component, it can be directly connected to the other component or there may be an intervening component. The terms "vertical," "horizontal," "left," "right," and similar expressions used in this document are for illustrative purposes only.

[0023] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0024] Please see Figure 1 The flowchart below illustrates a method for preparing a diamond-copper composite material with a discrete transition layer, as provided by the present invention. The method specifically includes the following steps: Step S01: Mix the pretreated diamond particles with tungsten powder evenly, load the mixture into an alumina crucible, and evenly cover the mixture with a mixture of NaCl and KCl salts.

[0025] Specifically, the diamond particles have a particle size of 50μm to 300μm. For example, the diamond particles have a particle size of 50μm, 100μm, 150μm, 200μm, 250μm or 300μm, but are not limited to these. The diamond particles are pretreated by washing with deionized water, degreasing with NaOH solution, and roughening with HNO3 solution.

[0026] Pretreated diamond particles and tungsten powder are mechanically mixed. A ball mill is used to mix for a certain period of time at a suitable speed to ensure uniform mixing. The uniformly mixed mixture is then placed into an alumina crucible and uniformly coated with a mixed salt of NaCl and KCl. The average particle size of the tungsten powder is 3μm~40μm, and the molar ratio of pretreated diamond particles to tungsten powder is 10~20:1 to achieve discrete deposition of tungsten carbide on the surface of the diamond particles. In this embodiment of the invention, the molar ratio of NaCl to KCl is 1:1, and the coating amount is 1 to 2 times the volume of the diamond particle and tungsten powder mixture. This mixed salt is used to promote the reaction during the coating process.

[0027] Step S02: Place the alumina crucible containing the material into a tube furnace and introduce argon gas to purge air and create a reducing atmosphere.

[0028] Step S03: Heat the tube furnace to allow tungsten powder to react with diamond particles, resulting in diamond particles coated with a discrete tungsten carbide transition layer.

[0029] It should be noted that the tube furnace is heated to 1050℃ and held for 10-60 minutes to allow the tungsten powder and diamond particles to react at high temperature, thus depositing tungsten carbide on the diamond surface. After the reaction is complete, the tube furnace is shut off and allowed to cool naturally to room temperature. The crucible is then removed, ultrasonically cleaned with deionized water to remove residual salts, and vacuum dried to obtain diamond particles with a discrete tungsten carbide transition layer on the surface. The coverage of the discrete tungsten carbide transition layer is 30%-70%.

[0030] Step S04: Diamond particles coated with a discrete tungsten carbide transition layer are dispersed in a copper sulfate electroplating solution and electrodeposited using a pulsed current to obtain a diamond-copper composite material with a discrete transition layer.

[0031] Specifically, 1000ml of copper sulfate electroplating solution is added to the electroplating tank, followed by the addition of diamond particles with a discrete tungsten carbide transition layer on the surface, and the mixture is magnetically stirred until homogeneous. The amount of diamond particles with a discrete tungsten carbide transition layer on the surface added to the copper sulfate electroplating solution is 2g / L to 10g / L. The copper sulfate electroplating solution is composed of 120g / L copper sulfate, 60g / L sulfuric acid, and 50mg / L chloride ions. The electrodeposition apparatus, which includes a cathode and an anode, is placed horizontally into the electroplating tank. Add the pre-mixed additive to the electroplating tank and stir it thoroughly with magnetic force. The pre-mixed additive consists of 10 ml / L sodium dithiodipropane sulfonate and 5 ml / L polyethylene glycol. The additive is replenished every 12 hours. A pulsed current is applied while maintaining a constant current density. Specifically, the electrodeposition temperature is 50°C, the forward current density of the pulsed current is 1A / dm²~6A / dm², and the reverse current density is 1~4 times the forward current density. The ratio of the forward to reverse time in one cycle of the pulsed current is 20:1. For example, if the duration of the forward pulsed current in one cycle is 20ms, then the duration of the reverse pulsed current in one cycle is 1ms. Control the stirring rate and stir intermittently to allow diamond particles with a discrete tungsten carbide transition layer deposited on the surface to naturally settle onto the cathode surface under gravity and participate in copper substrate electrodeposition. The stirring rate is 80 rpm to 350 rpm. For example, first stir at 350 rpm for 1 min, then stir at 80 rpm for 10 min, and repeat the above operation to perform intermittent stirring. The cathode substrate is removed by rinsing with deionized water to obtain a diamond-copper composite material with a discrete transition layer. In this embodiment of the invention, after the expected thickness is reached, the circuit is disconnected, the cathode substrate and the composite sample are removed, and the sample is rinsed clean with deionized water multiple times. The cathode substrate and the composite sample are then immersed in hydrofluoric acid solution until the titanium sheet is completely removed. The sample is then rinsed with deionized water multiple times and dried with nitrogen gas to obtain a diamond-copper composite material with a discrete transition layer. The concentration of the hydrofluoric acid solution is 5%.

[0032] In summary, the present invention provides a method for preparing a diamond-copper composite material with a discrete transition layer. This method utilizes an electrodeposition apparatus with a phosphor bronze anode and a titanium or copper-plated substrate as the cathode. Diamond particles coated with a discrete tungsten carbide transition layer are dispersed in a copper sulfate electrolyte and electrodeposited using a pulsed current to obtain the diamond-copper composite material with the discrete transition layer. Specifically, the pretreated diamond particles are uniformly mixed with tungsten powder, and the mixture is placed in an alumina crucible. A mixed salt of NaCl and KCl is uniformly coated on the mixture. The alumina crucible containing the material is placed in a tube furnace, and argon gas is introduced to purge air and create a reducing atmosphere. The tube furnace is heated to allow the tungsten powder to react with the diamond particles, resulting in diamond particles coated with a discrete tungsten carbide transition layer. This discrete structure improves interfacial wettability and enhances interfacial bonding strength. It also forms insulating gaps through uncoated areas, inhibiting the continuity of the conductive network and reducing porosity defects in the copper plating layer. Ultimately, this effectively improves the density and thermal conductivity of the diamond-copper composite material.

[0033] In another aspect, the present invention also proposes a diamond-copper composite material with a discrete transition layer, which is prepared by the above-described method for preparing a diamond-copper composite material with a discrete transition layer.

[0034] To facilitate understanding of the present invention, several embodiments are given below. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided so that the disclosure of the present invention will be more thorough and complete.

[0035] Example 1 This invention provides a method for preparing a diamond-copper composite material with a discrete transition layer. First, diamond particles with an average particle size of 100 μm are pretreated by washing with deionized water, degreasing with NaOH solution, and roughening with HNO3 solution. The pretreated diamond particles are then mechanically mixed uniformly with tungsten powder with an average particle size of 40 μm at a molar ratio of 10:1. The uniformly mixed mixture is placed in an alumina crucible and uniformly covered with a 1:1 molar ratio of NaCl and KCl, with a coverage amount twice the volume of the material. The crucible is placed in a tube furnace, and under an argon atmosphere, the furnace is heated to 1050°C and held for 30 minutes to coat the diamond surface with tungsten carbide, achieving a 50% coverage. After the reaction, the tube furnace is closed and cooled to room temperature. The crucible is then removed, ultrasonically cleaned three times with deionized water to remove residual salts, and vacuum dried to obtain diamond particles coated with discrete tungsten carbide. (See also...) Figure 2 The image shown is a scanning electron microscope (SEM) image of diamond particles with a discrete tungsten carbide transition layer coated on their surface, as described in Embodiment 1 of the present invention. Please refer to [link / reference]. Figure 3 The image shows the X-ray diffraction pattern of diamond particles with a discrete tungsten carbide transition layer coated on their surface, as described in Embodiment 1 of the present invention.

[0036] Add 1000 mL of an electroplating solution composed of 120 g / L copper sulfate, 60 g / L sulfuric acid, and 50 mg / L chloride ions to the electroplating tank. Add 3 g of diamond particles with a discrete tungsten carbide transition layer on the surface, and continue magnetic stirring at 450 rpm for 1 min. Place the cathode and anode devices horizontally in the electroplating tank, and add an additive composed of 10 ml / L sodium dithiodipropane sulfonate and 5 ml / L polyethylene glycol. Stir thoroughly with magnetic stirring at 450 rpm until homogeneous. Replenish the additive periodically every 12 hours, and apply a pulsed current. The duration of the forward pulse current in one cycle is 20 ms, and the duration of the reverse pulse current in one cycle is 1 ms. Maintain a forward current density of 2 A / dm² and a reverse current density of 6 A / dm². Stir at 350 rpm for 1 min, then at 80 rpm for 10 min. Repeat the above operation with intermittent stirring to allow the diamond particles with the discrete tungsten carbide transition layer to naturally settle to the cathode surface under gravity and participate in the copper substrate electrodeposition. The plating time is 60 min. Once the desired thickness is achieved, disconnect the circuit, remove the cathode substrate and composite sample, and rinse thoroughly with deionized water multiple times. Immerse the cathode substrate and composite sample in a 5% hydrofluoric acid solution until the titanium sheet is completely removed, then rinse repeatedly with deionized water. Dry the composite sample with nitrogen gas to obtain a diamond-copper composite material with a discrete transition layer, exhibiting a thermal conductivity of 582 W / (m·K). Please refer to [link / reference]. Figure 4 The image shown is a scanning electron microscope (SEM) image of the diamond-copper composite material with a discrete transition layer in Embodiment 1 of the present invention. Please refer to [link / reference]. Figure 5This is a cross-sectional scanning electron microscope image of the diamond-copper composite material with a discrete transition layer in Embodiment 1 of the present invention.

[0037] Example 2 Embodiment 2 of the present invention also provides a method for preparing a diamond-copper composite material with a discrete transition layer. The difference from Embodiment 1 is that diamond particles with an average particle size of 100 μm are pretreated. The pretreated diamond particles are mechanically mixed uniformly with tungsten powder with an average particle size of 10 μm at a molar ratio of 20:1, and the coating time is 30 min. The final diamond-copper composite material with a discrete transition layer has a thermal conductivity of 576 W / (m·K). Please refer to [link to previous documentation]. Figure 6 This is a scanning electron microscope image of the diamond-copper composite material with a discrete transition layer in Embodiment 2 of the present invention.

[0038] Example 3 This third embodiment also provides a method for preparing a diamond-copper composite material with a discrete transition layer. The difference from the first embodiment is that the forward current density of the pulsed current is 1 A / dm², the reverse current density is 4 A / dm², and the thermal conductivity of the diamond-copper composite material with a discrete transition layer obtained is 589 W / (m·K).

[0039] Example 4 This fourth embodiment also provides a method for preparing a diamond-copper composite material with a discrete transition layer. The difference from the first embodiment is that the pulse current density is 6 A / dm², the reverse current density is 12 A / dm², and the thermal conductivity of the diamond-copper composite material with a discrete transition layer obtained is 554 W / (m·K).

[0040] Comparative Example 1 Comparative Example 1 provides a method for preparing a diamond-copper composite material with a discrete transition layer. Diamond with an average size of 100 μm and tungsten powder with an average size of 40 μm are uniformly mixed at a molar ratio of 10:1. A continuous tungsten carbide transition layer is deposited on the surface of the diamond particles under the following conditions: 1050℃ for 60 min. The deposited diamond particles are then placed in an electroplating bath with a phosphor bronze anode and a titanium or copper-plated substrate as the cathode. Electrodeposition is performed at a pulsed current with a forward current density of 2 A / dm² and a reverse current density of 6 A / dm², at a constant temperature of 50℃ for 60 min. The resulting diamond-copper composite material with a continuous transition layer and a diameter of 12.6 mm has a thermal conductivity of 478 W / (m·K). Please refer to [link to relevant documentation]. Figure 7 This is a scanning electron microscope image of the diamond-copper composite material with a continuous transition layer in Comparative Example 1 of the present invention.

[0041] The thermal conductivity test method used in Embodiments 1 to 4 of this invention, and in Comparative Example 1, is the laser flare method. Specific results are shown in the table below:

[0042] As shown in the table above, the diamond-copper composite material prepared in the embodiments of the present invention has fewer pores and defects in the copper coating compared with the existing diamond-copper composite material, the composite material has higher density and effectively improved thermal conductivity.

[0043] In the description of this specification, references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0044] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention. Therefore, the scope of protection of this patent should be determined by the appended claims.

Claims

1. A method of producing a diamond-copper composite material having a discrete transition layer, characterized by, The application is applied to an electrodeposition device with an anode of phosphor copper plate and a cathode of titanium plate or copper plated substrate, and comprises the following steps. The pretreated diamond particles and tungsten powder are mixed uniformly, the mixture is loaded into an alumina crucible, and a mixed salt of NaCl and KCl is uniformly covered on the mixture; The alumina crucible loaded with the material is placed into a tube furnace, argon is introduced to exclude air and create a reducing atmosphere; The tube furnace is heated to make the tungsten powder react with the diamond particles, and diamond particles with a surface plated with discrete tungsten carbide transition layer are obtained; The diamond particles with the surface plated with discrete tungsten carbide transition layer are dispersed in a copper sulfate electroplating solution, and electrodeposition is carried out by using pulse current to obtain diamond copper composite material with discrete transition layer.

2. The method of claim 1, wherein the diamond-copper composite material having a discrete transition layer is prepared by the steps of: The average particle size of the tungsten powder is 3-40 μm.

3. The method of claim 2, wherein the method further comprises: The molar ratio of the pretreated diamond particles to the tungsten powder is 10-20:

1.

4. The method of claim 3, wherein the copper is heated to a temperature of 900- 1000°C. In the step of heating the tube furnace to make the tungsten powder react with the diamond particles, the tube furnace is heated to 1050°C and kept for 10-60 min.

5. The method of claim 4, wherein the copper-diamond composite material having a discrete transition layer is prepared by the steps of: The particle size of the diamond particles is 50-300 μm.

6. The method of claim 5, wherein the method further comprises: The coverage of the surface plated with discrete tungsten carbide transition layer is 30-70%.

7. The method of claim 6, wherein the method further comprises: The step of dispersing the diamond particles with the surface plated with discrete tungsten carbide transition layer in the copper sulfate electroplating solution, and carrying out electrodeposition by using pulse current to obtain diamond copper composite material with discrete transition layer comprises: The copper sulfate electroplating solution is added into an electroplating tank, then the diamond particles with the surface plated with discrete tungsten carbide transition layer are added, and magnetic stirring is carried out uniformly, the copper sulfate electroplating solution is composed of 120 g / L copper sulfate, 60 g / L sulfuric acid and 50 mg / L chloride ion; The electrodeposition device with a cathode and an anode is horizontally placed into the electroplating tank; The pre-proportioned additive is added into the electroplating tank, and magnetic stirring is carried out uniformly, wherein the pre-proportioned additive is composed of 10 ml / L polydithiopropanesulfonic acid sodium and 5 ml / L polyethylene glycol, and the additive is supplemented every 12 h; Pulse current is introduced, and the current density is kept constant; The stirring speed is controlled, and intermittent stirring is carried out, so that the diamond particles with the surface plated with discrete tungsten carbide transition layer are naturally settled on the surface of the cathode under the action of gravity, and participate in copper substrate electrodeposition; Deionized water is used for flushing to remove the cathode substrate, and diamond copper composite material with discrete transition layer is obtained.

8. The method of claim 7, wherein the method further comprises: In the step of carrying out electrodeposition by using pulse current, the electrodeposition temperature is 50°C, the forward current density of the pulse current is 1-6 A / dm2, the reverse current density is 1-4 times of the forward current density, and the ratio of the forward time to the reverse time in one cycle of the pulse current is 20:

1.

9. The method of claim 8, wherein the method further comprises, The amount of the diamond particles with the surface plated with discrete tungsten carbide transition layer added into the copper sulfate electroplating solution is 2-10 g / L.

10. A diamond-copper composite material having a discrete transition layer, characterized in that, The diamond copper composite material with discrete transition layer is prepared by the preparation method of any one of claims 1-9.

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