Diamond-coated composite materials, copper composite materials and their preparation methods

Abstract

This invention discloses a diamond-coated composite material, a copper composite material, and their preparation methods. It belongs to the technical field of diamond composite materials. The preparation of the diamond-coated composite material includes: depositing an amorphous carbon film on the surface of cleaned diamond particles and performing a first heat treatment to obtain amorphous carbon-coated diamond; depositing a metal layer on the surface of the amorphous carbon-coated diamond and performing a second heat treatment to obtain coated diamond; and performing a third heat treatment on the coated diamond to obtain the diamond-coated composite material. The preparation method of this invention can significantly reduce damage to the diamond matrix and provide a uniform and active surface for its metallization treatment, resulting in a diamond-copper composite material with tight and uniform interfacial bonding and excellent overall performance.

Description

Technical Field

[0001] This invention relates to the technical field of diamond composite materials, and particularly to a diamond-coated composite material, a copper composite material, and a method for preparing the same. Background Technology

[0002] Diamond is considered an ideal heat dissipation component for next-generation high-performance electronic packaging materials due to its extremely high thermal conductivity. Diamond / metal composite materials, prepared by combining diamond with metals such as copper, aluminum, and silver, can combine the excellent thermal conductivity of diamond with the good plasticity and electrical conductivity of metals. This results in novel packaging and thermal management materials with high thermal conductivity, adjustable coefficient of thermal expansion, and high strength, meeting the ever-growing demands of modern electronic devices for high power, high density, and miniaturization.

[0003] Among numerous diamond / metal composite materials, diamond-copper composites are particularly noteworthy. They combine the high thermal conductivity of diamond with the excellent electrical conductivity of copper, and through proper component design, can achieve a thermal expansion coefficient that matches that of semiconductor chips. Therefore, they have broad application prospects in the field of electronic packaging, especially in high-end areas such as aerospace, 5G communications, and high-performance computing.

[0004] However, diamond and copper have extremely poor wettability and do not undergo interfacial reactions thermodynamically. As a result, under conventional preparation processes, the two-phase interface inside the diamond-copper composite material is fragile, which becomes the main obstacle to phonon scattering and heat conduction. The actual thermal conductivity of the resulting composite material is far lower than theoretically expected.

[0005] To overcome the above problems, existing technologies generally adopt a diamond surface metallization strategy, that is, pre-plating a metal or transition layer on the diamond surface to improve its wettability and bonding strength with the copper substrate. However, diamond has a cubic crystal structure and exhibits obvious anisotropy. For example, among the main crystal faces (100) and (111) for surface plating, the atomic arrangement of the (111) face is more dense and less likely to be wetted during the surface plating process, while the (100) face is relatively easier to be plated with metal. This anisotropy leads to significant differences in plating effect, plating thickness and bonding strength on different crystal faces of the same diamond particle, directly affecting the interface uniformity and stability of subsequent composite with copper.

[0006] To address this issue, existing technologies further employ etching processes on the surface of diamond particles. This creates nanoscale roughness or channels to improve the overall wettability of the diamond and enhance the adhesion and uniformity of the coating. For example, prior art CN114572979A discloses a diamond etching method with surface nanopores. This method mainly includes: acid and alkali pretreatment of the diamond to remove surface impurities; subsequently, wetting the diamond with a diluted ferric chloride solution and microwave drying; followed by high-temperature etching at 700°C to 1000°C under a hydrogen atmosphere; and finally, cleaning with hydrochloric acid and ultrasonic vibration to obtain a diamond with nanopores on its surface.

[0007] However, this existing technology has the following prominent problems: First, the anisotropy of the diamond crystal structure determines that the reaction rates of different crystal planes are inconsistent during the plating and etching processes, and direct plating will lead to uneven coating thickness; Second, this traditional etching technology directly erodes the diamond particles, which, although improving the coating adhesion to some extent, inevitably damages the integrity of the diamond crystal and weakens its essential advantage as a high thermal conductivity filler; In addition, in this method, it is difficult to achieve uniformity and precise control of the corrosion degree, and the process repeatability is poor. These factors will ultimately have a negative impact on the thermal conductivity of diamond-copper composite materials.

[0008] Therefore, there is an urgent need for a novel surface modification method that can effectively improve the uniformity and adhesion of the surface coating while maintaining the integrity of the diamond crystal to the greatest extent. Summary of the Invention

[0009] To address the shortcomings of existing technologies, the present invention aims to propose a novel diamond-coated composite material, a diamond-copper composite material, and a method for preparing the same. The preparation method employs a strategy of coating the surface of diamond particles with an amorphous carbon film to obtain a diamond-coated composite material containing a carbide metal coating, and further obtains a diamond-copper composite material. This preparation method can significantly reduce damage to the diamond matrix and provide a uniform and active surface for its metallization treatment, resulting in a diamond-copper composite material with tight and uniform interfacial bonding and excellent overall performance.

[0010] The technical solution of the present invention is as follows:

[0011] A method for preparing a diamond-coated composite material, comprising the following steps:

[0012] (1) The diamond particles were ultrasonically cleaned with an organic solvent and then dried to obtain cleaned diamond.

[0013] (2) A layer of amorphous carbon film is deposited on the cleaned diamond surface by deposition to obtain a first amorphous carbon-coated diamond;

[0014] (3) The first amorphous carbon-coated diamond is subjected to a first heat treatment to obtain a second amorphous carbon-coated diamond; the first heat treatment includes: vacuum holding the first amorphous carbon-coated diamond at 400-800℃ for 0.5-2h;

[0015] (4) A metal layer is deposited on the surface of the second amorphous carbon-coated diamond to obtain a first-coated diamond;

[0016] (5) The first coated diamond is subjected to a second heat treatment to obtain a second coated diamond; the second heat treatment includes: vacuum holding the first coated diamond at 400-800℃ for 0.5-2h;

[0017] (6) The second coated diamond is subjected to a third heat treatment to obtain the diamond coated composite material; the third heat treatment includes: heating the second coated diamond to 700-1100℃ in a vacuum at a heating rate of 5-10℃ / min and holding it for 180-240min.

[0018] In the above preparation method of the present invention, the obtained second-coated diamond has a composite coating structure on the surface of the diamond particles, including an amorphous carbon thin film layer and a metal coating layer. The amorphous carbon thin film layer is located on the surface of the diamond particles, which does not damage the diamond particles and can provide a certain degree of protection. The metal coating layer is further located on the surface of the amorphous carbon thin film layer, which is less affected by the anisotropy of the diamond particles and can ensure uniform coating on each surface. Subsequently, in the third heat treatment in step (6), the atoms diffuse fully through diffusion, the amorphous carbon thin film layer disappears, and the metal elements in the metal coating layer fully combine with carbon atoms to form metal carbide compounds, which significantly improves the bonding force between the metal coating layer and each surface of the diamond.

[0019] According to some preferred embodiments of the present invention, the preparation method further includes: repeating steps (2)-(5) to obtain a third coated diamond, and subjecting the third coated diamond to the third heat treatment; in the third coated diamond, the thickness ratio of the amorphous carbon film to the coated metal layer is 1:2-7.

[0020] According to some preferred embodiments of the present invention, the ultrasonic cleaning includes: ultrasonically cleaning the diamond particles with acetone for 10-30 minutes, followed by ultrasonic cleaning with alcohol for another 10-30 minutes.

[0021] According to some preferred embodiments of the present invention, the diamond particles have a particle size of 50-400 μm.

[0022] According to some preferred embodiments of the present invention, the thickness of the amorphous carbon film in step (2) is 10-50 nm.

[0023] According to some preferred embodiments of the present invention, the thickness of the metal layer in step (4) is 50-100 nm.

[0024] According to some preferred embodiments of the present invention, the vacuum degree is 10. -2 Below Pa.

[0025] According to some preferred embodiments of the present invention, the deposition in step (2) is performed by one or more of physical vapor deposition, chemical vapor deposition, microwave deposition, plasma electrodeposition, and pulsed laser deposition.

[0026] According to some preferred embodiments of the present invention, the plating in step (4) is performed by magnetron sputtering and / or evaporation plating.

[0027] According to some preferred embodiments of the present invention, the composition of the metal layer is selected from one or more of Ti, Mo, and W.

[0028] The present invention further provides a diamond-coated composite material obtained according to the above preparation method.

[0029] The present invention further provides a method for preparing a diamond-copper composite material, which involves combining the diamond-coated composite material with copper by gas pressure melting and / or vacuum hot pressing sintering to obtain a diamond-copper composite material.

[0030] According to some preferred embodiments of the present invention, the preparation of the diamond-copper composite material includes: placing the coated diamond and copper block into a graphite mold for gas pressure infiltration. The gas pressure infiltration process includes: evacuating to below 10 Pa, then heating to 1200-1300°C and holding for 0.5-1 h, then pressurizing to 4-10 MPa and holding for 20-30 min, then cooling to 650-750°C, depressurizing, then continuously cooling to 50-150°C, breaking the vacuum, and cooling to obtain the diamond-copper composite material.

[0031] The present invention further provides a diamond-copper composite material prepared according to the above preparation method.

[0032] This diamond-copper composite material, through pressure melting and infiltration, achieves good interfacial bonding between diamond and copper matrix, and the thermal conductivity of the composite material can reach 900 W / (m·K), effectively improving the thermal conductivity of the composite material.

[0033] The present invention has the following beneficial effects:

[0034] The preparation method of this invention first coats the diamond surface with an amorphous carbon thin film layer, which can significantly improve the anisotropy of diamond when coated with metal, without affecting the integrity of the diamond particle crystal structure. Then, through coating carbonization treatment, the thin film graphite layer disappears through diffusion, resulting in diamond particles with metal carbides as the surface phase. The formed coating is continuous, the coating thickness of different crystal planes is uniform, the particles and coating are well bonded, and there is no peeling phenomenon. Finally, through heat treatment and gas pressure melting infiltration, a diamond-copper composite material with tight and uniform interfacial bonding and excellent comprehensive performance can be obtained. Attached Figure Description

[0035] Figure 1 The image shows a SEM image of the diamond-coated composite material obtained in Example 1, where (a) is an image magnified 100 times and (b) is an image magnified 500 times.

[0036] Figure 2 The following are comparative XRD patterns of the diamond-coated composite materials of Examples 1-2 and Comparative Example 1;

[0037] Figure 3 The image shows a comparison of the coating thickness of the diamond-coated composite materials obtained in Example 1(a) and Comparative Example 1(b). Detailed Implementation

[0038] The technical solutions of the present invention will be further described below with reference to embodiments thereof. The embodiments described below are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort should fall within the scope of protection of the present invention.

[0039] Example 1

[0040] Diamond-coated composite materials are prepared using the following process:

[0041] (1) Select diamond particles with a particle size of 400 μm, and ultrasonically clean them with acetone for 20 min and with alcohol for 20 min in sequence. Dry the cleaned diamond particles to obtain cleaned diamond particles.

[0042] (2) Amorphous carbon thin film with a thickness of 20 nm was deposited on the surface of the cleaned diamond particles by magnetron sputtering to obtain the first amorphous carbon coated diamond particles.

[0043] (3) The carbon film diamond particles were subjected to heat treatment at 600℃ and vacuum heat preservation for 1h to eliminate their coating stress and obtain the second amorphous carbon-coated diamond particles.

[0044] (4) Tungsten metal is deposited on the surface of the second amorphous carbon-coated diamond particles by magnetron sputtering, with a coating thickness of 100 nm, to obtain the first tungsten-coated diamond particles.

[0045] (5) The tungsten-coated diamond particles were subjected to heat treatment at 600°C and vacuum heat preservation for 1 hour to eliminate the coating stress and obtain the second tungsten-coated diamond particles.

[0046] (6) When the vacuum degree is controlled at 10 -2 In a vacuum furnace at Pa, the second tungsten-coated diamond particles were heated to 1100°C at a heating rate of 5°C / min and held at that temperature for 240 min to obtain a diamond particle sample with tungsten carbide as the surface phase, which is the diamond-coated composite material.

[0047] Diamond-copper composite material was prepared by the following gas pressure melting process: The diamond-coated composite material obtained in Example 1 was loaded into a graphite mold and copper blocks were added. The copper blocks covered the graphite mold to a thickness of 5 cm. Then, it was placed in a gas pressure melting furnace, and the vacuum was evacuated to 10 Pa. After the vacuum stabilized, it was heated to 1200°C and held for 1 h. Then, the pressure was increased to 6 MPa and held for 20 min. The furnace was cooled to 700°C to release the pressure. The vacuum was broken by cooling to 100°C and the diamond-copper composite material was obtained after complete cooling.

[0048] SEM images of the obtained diamond-coated composite material are attached. Figure 1 As shown, (a) is an image magnified 100×, and (b) is an image magnified 500×. Figure 1 It can be seen that the coating on the surface of the obtained diamond particles is uniform and complete, and there are no uncoated particles within the field of view.

[0049] Example 2

[0050] Diamond-coated composite materials are prepared using the following process:

[0051] (1) Select diamond particles with a particle size of 400 μm, and ultrasonically clean them with acetone for 20 min and with alcohol for 20 min in sequence. Dry the cleaned diamond particles to obtain cleaned diamond particles.

[0052] (2) Amorphous carbon thin film with a thickness of 30 nm was deposited on the surface of the cleaned diamond particles by magnetron sputtering to obtain the first amorphous carbon coated diamond particles.

[0053] (3) The carbon film diamond particles were subjected to heat treatment at 600℃ and vacuum heat preservation for 1h to eliminate their coating stress and obtain the second amorphous carbon-coated diamond particles.

[0054] (4) Tungsten metal is deposited on the surface of the second amorphous carbon-coated diamond particles by magnetron sputtering, with a coating thickness of 100 nm, to obtain the first tungsten-coated diamond particles.

[0055] (5) The tungsten-coated diamond particles were subjected to heat treatment at 600°C and vacuum heat preservation for 0.5h to eliminate the coating stress and obtain the second tungsten-coated diamond particles.

[0056] (6) Amorphous carbon thin film with a thickness of 20 nm is deposited on the surface of the second tungsten-coated diamond particles by magnetron sputtering to obtain the third amorphous carbon-coated diamond particles.

[0057] (7) The diamond particles were subjected to heat treatment at 600℃ and vacuum heat preservation for 0.5h to eliminate their coating stress and obtain the fourth amorphous carbon coated diamond particles.

[0058] (8) Tungsten metal was deposited on the surface of the fourth amorphous carbon-coated diamond particles by magnetron sputtering, with a coating thickness of 100 nm, to obtain the third tungsten-coated diamond particles.

[0059] (9) The tungsten-coated diamond particles were subjected to heat treatment at 500°C and vacuum heat preservation for 0.5h to eliminate coating stress and obtain the fourth tungsten-coated diamond particles.

[0060] (10) When the vacuum degree is controlled at 10 -2 In a vacuum furnace at Pa, the fourth tungsten-coated diamond particles were heated to 1100°C at a heating rate of 5°C / min and held at that temperature for 210 min to obtain a diamond particle sample with tungsten carbide as the surface phase, which is the diamond-coated composite material.

[0061] The diamond-coated composite material was prepared into a diamond-copper composite material using the same gas pressure melting process as in Example 1.

[0062] Comparative Example 1

[0063] Comparative examples of diamond-copper composite materials were prepared using the following process:

[0064] (1) Select diamond particles with a particle size of 400 μm, and ultrasonically clean them with acetone for 20 min and with alcohol for 20 min in sequence. Dry the cleaned diamond particles to obtain cleaned diamond particles.

[0065] (2) Tungsten-coated diamond particles were obtained by magnetron sputtering to coat the surface of diamond particles with a coating thickness of 200 nm.

[0066] (3) When the vacuum degree is controlled at 10 -2In a vacuum furnace with a pressure of Pa, tungsten-coated diamond particles were heated to 1100℃ at a heating rate of 5℃ / min and held at that temperature for 240min to obtain a diamond-coated composite material.

[0067] The diamond-coated composite material was prepared into a diamond-copper composite material using the same gas pressure melting process as in Example 1.

[0068] The diamond-coated composite materials obtained in Examples 1-2 and Comparative Example 1 were subjected to XRD tests, and the test results are shown in the appendix. Figure 2 As shown.

[0069] Through append Figure 2 It can be seen that the surface phases of the diamond-coated composite materials obtained in the examples and comparative examples are all tungsten carbide, with no graphite phase.

[0070] Furthermore, the diamond-coated composite materials obtained in Example 1 and Comparative Example 1 were mechanically crushed. The crushed diamond-coated composite materials were characterized by SEM, and the thickness of the coating film on the diamond particles was measured. The results are shown in the attached figure. Figure 3 As shown, (a) is Example 1 and (b) is Comparative Example 1.

[0071] Through append Figure 3 As can be seen, the coating thickness obtained in Example 1 is 128.25 nm, while the coating thickness obtained in Comparative Example 1 is 198.67 nm. Compared with Comparative Example 1, the coating thickness of Example 1 is more uniform.

[0072] Furthermore, the thermal conductivity of the diamond-copper composite materials of Examples 1, 2 and Comparative Example 1 was tested using the flash method, and the test results are shown in Table 1.

[0073] Table 1. Thermal conductivity test results of diamond-copper composite materials

[0074]

[0075] As can be seen from Table 1, the thermal conductivity of the diamond-copper composite material obtained in the examples is significantly higher than that in Comparative Example 1, and the thermal conductivity of the diamond-copper composite material obtained in Example 1 is the best.

[0076] It should be noted that the above descriptions are merely preferred embodiments of the present invention and should not limit the scope of protection of the technical solutions of the present invention. Any modifications made to the technical solutions described in the foregoing embodiments, or equivalent substitutions of technical features, by those skilled in the art within the spirit and principles of the present invention, should be included within the scope of protection of the present invention.

Claims

1. A method for preparing a diamond-coated composite material, characterized in that, It includes the following steps: (1) The diamond particles were ultrasonically cleaned with an organic solvent and then dried to obtain cleaned diamond. (2) A layer of amorphous carbon film is deposited on the cleaned diamond surface by deposition to obtain a first amorphous carbon-coated diamond; (3) The first amorphous carbon-coated diamond is subjected to a first heat treatment to obtain a second amorphous carbon-coated diamond; the first heat treatment includes: vacuum holding the first amorphous carbon-coated diamond at 400-800℃ for 0.5-2h; (4) A metal layer is deposited on the surface of the second amorphous carbon-coated diamond to obtain a first-coated diamond; (5) The first coated diamond is subjected to a second heat treatment to obtain a second coated diamond; the second heat treatment includes: vacuum holding the first coated diamond at 400-800℃ for 0.5-2h; (6) The second coated diamond is subjected to a third heat treatment to obtain the diamond coated composite material; the third heat treatment includes: heating the second coated diamond to 800-1100℃ in a vacuum at a heating rate of 5-10℃ / min and holding it for 180-240min.

2. The preparation method according to claim 1, characterized in that, It also includes: repeating steps (2)-(5) to obtain a third coated diamond, and performing the third heat treatment on the third coated diamond; in the third coated diamond, the thickness ratio of the amorphous carbon film to the coated metal layer is 1:2-7.

3. The preparation method according to claim 1, characterized in that, The ultrasonic cleaning process includes ultrasonic cleaning of the diamond particles with acetone for 10-30 minutes, followed by ultrasonic cleaning with alcohol for another 10-30 minutes.

4. The preparation method according to claim 1, characterized in that, in, The diamond particles have a particle size of 50-400 μm; and / or, the amorphous carbon film in step (2) has a thickness of 10-50 nm; and / or, the metal layer in step (4) has a thickness of 50-100 nm; the vacuum degree of the vacuum is 10 -2 Below Pa.

5. The preparation method according to claim 1, characterized in that, The deposition in step (2) is performed by chemical vapor deposition and / or pulsed laser deposition; and / or the plating in step (4) is performed by magnetron sputtering and / or evaporation plating.

6. The preparation method according to claim 1, characterized in that, The composition of the metal layer includes one or more of Ti, Mo, and W.

7. The diamond-coated composite material prepared by the preparation method according to any one of claims 1-6.

8. A method for preparing a diamond-copper composite material, characterized in that, A diamond-copper composite material is obtained by combining the diamond-coated composite material of claim 7 with copper using gas pressure melting and / or vacuum hot pressing sintering.

9. The preparation method according to claim 8, characterized in that, The preparation of the diamond-coated copper composite material includes: placing the diamond-coated composite material and a copper block into a graphite mold for gas pressure melting and infiltration. The gas pressure melting and infiltration process includes: evacuating to below 10 Pa, then heating to 1200-1300℃ and holding for 0.5-1 h, then pressurizing to 4-10 MPa and holding for 20-30 min, then cooling to 650-750℃, depressurizing, then continuously cooling to 50-150℃, breaking the vacuum, and cooling to obtain the diamond-coated copper composite material.

10. The diamond-copper composite material prepared by the preparation method according to claim 9.

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