Preparation method of copper-based diamond composite heat dissipation material
By employing high-temperature and high-pressure sintering and surface treatment technologies, the challenges of interfacial bonding and densification in copper-based diamond composite materials were solved, resulting in the preparation of high-performance copper-based diamond composite materials that enable efficient heat dissipation and thermal stress management for semiconductor devices.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- SUPERHARD MATERIALS IND TECHNOLOGY RESEARCH INSTITUTE
- Filing Date
- 2026-01-16
- Publication Date
- 2026-04-21
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Figure FT_1
Abstract
Description
Technical Field
[0001] This invention belongs to the field of copper-based diamond technology, and specifically relates to a method for preparing a copper-based diamond composite heat dissipation material. Background Technology
[0002] As the power density of semiconductor devices continues to increase, efficient heat dissipation has become a key issue restricting their performance and reliability. Copper-based diamond composites, due to their high thermal conductivity and tunable coefficient of thermal expansion, are considered ideal candidate materials for solving this problem, showing significant application potential in fields such as electronics and power modules.
[0003] However, the inherent differences in physical and chemical properties between diamond and the copper matrix result in extremely poor wettability between them. Figure 1 a) Interfacial bonding is difficult; even at a high temperature of 1100℃, the contact angle remains at 130°, and no solid solution or chemical reaction occurs between the two. Figure 1 (b) It is difficult to form a strong covalent bond. This makes the composite material composed of the two prone to forming high interfacial thermal resistance during the preparation process, which seriously reduces its overall thermal conductivity. Figure 1 c). The thermal conductivity of some existing composite materials is only around 200 W / m·K, even lower than that of pure copper, failing to leverage the high thermal conductivity advantage of diamond. Materials Science and Engineering: A [, 2008, 475, 39]. Therefore, the interfacial bonding problem has become the main bottleneck restricting the improvement of the material's performance.
[0004] The existing technology currently has the following main problems: (1) Poor interfacial bonding and high thermal resistance: Due to the poor wettability between diamond and copper matrix, direct composite will result in weak interfacial bonding and significant interfacial thermal resistance, which will lead to low overall thermal conductivity of composite material, possibly even lower than that of pure copper matrix, which seriously restricts its application potential as a high thermal conductivity heat dissipation material.
[0005] (2) Difficulty in controlling the surface coating process: To improve the interface, diamond particles are often surface metallized. However, the surface of industrial diamond particles is smooth, and the bonding strength between the coating and the particles is insufficient. Furthermore, the thickness and uniformity of the coating are extremely difficult to control precisely: if the coating is too thin, the improvement effect is limited; if it is too thick, additional interfacial thermal resistance will be introduced. The process window is narrow, the cost is high, and the repeatability is poor, which hinders its large-scale and stable production.
[0006] (3) Traditional sintering processes are prone to causing diamond performance degradation: When using traditional processes such as solution infiltration, hot pressing or spark plasma sintering (SPS), it is often difficult to completely suppress the graphitization transformation of diamond at high temperatures due to the limited temperature and pressure conditions; once graphitization occurs, the thermal conductivity of diamond itself will drop sharply, thereby seriously degrading the final thermal conductivity of the composite material.
[0007] (4) Insufficient material densification: Due to safety and equipment limitations, the sintering temperature of the aforementioned traditional sintering processes (such as hot pressing and SPS) is usually lower than the melting point of copper, and the applied pressure is also limited (≤300 MPa). This results in poor fluidity of the copper matrix, making it difficult to completely fill the pores and achieve close contact with diamond, ultimately leading to low density of the composite material. Residual pores and uneven phase distribution in the material will form heat scattering centers, further reducing properties such as thermal conductivity.
[0008] To improve interfacial properties, current research mainly focuses on two aspects: raw material pretreatment and sintering process. Regarding raw material treatment, methods such as copper matrix alloying or diamond surface plating with metal layers (e.g., chromium, titanium, zirconium) are commonly used, aiming to enhance interfacial bonding by forming a metal carbide transition layer. For example, Pan et al. deposited a zirconium layer approximately 500 nm thick on a diamond surface using magnetron sputtering, followed by spark plasma sintering (SPS) to form a zirconium carbide interfacial layer, preparing a composite material with a thermal conductivity of 609 W / (m·K). Materials , 2019, 12, 475. Nevertheless, this type of method still has significant shortcomings: the thickness of the transition layer is difficult to control precisely—too thin and the interface bonding is weak; too thick and additional interface thermal resistance is introduced. Compos. Part A: Appl. Sci. Manuf. [, 2018, 113, 76]; At the same time, the uniformity of the coating is not easy to guarantee, which increases the complexity of the process and the production cost.
[0009] In sintering preparation, the mainstream technologies currently include spark plasma sintering (SPS) and melt infiltration. However, these methods generally suffer from low process pressure (typically ≤500 MPa) and limited sintering temperature, making it difficult to achieve a tight bond and densification between copper and diamond, and leading to diamond graphitization, which affects the thermal conductivity of the composite material. In contrast, high-temperature and high-pressure methods can be used for sintering at higher pressures (≥1 GPa) and temperatures, which not only inhibits diamond graphitization but also significantly improves the wettability of copper and diamond, providing a new approach for preparing high-performance composite materials. Chen Hui et al. from Beijing University of Science and Technology synthesized a bulk material with a thermal conductivity of 750 W / (m·K) under conditions of 6 GPa and 1200 ℃, in which diamond accounted for as much as 10%. However, since no carbide transition layer was formed between the diamond and copper in this bulk material, cracks would occur at high temperatures due to the large difference in the coefficients of thermal expansion between diamond and copper, thus significantly reducing its thermal conductivity.
[0010] The invention disclosed in CN114752809A is a diamond-copper composite material and its preparation method. The key technical points include the following steps: pre-setting the matrix type and diamond; wherein the matrix is either a copper alloy or pure copper; pre-treating the diamond based on the matrix type; wherein the pre-treatment includes at least: coating the diamond with a connecting film; assembling the pre-treated diamond and the matrix in a mold from bottom to top according to a predetermined ratio; placing the mold in an equipment to prepare the diamond-copper composite material. The pre-treatment mainly involves adding a connecting film between the copper and the diamond and coating the diamond with a SiC-metal composite film to improve the interfacial strength between the copper and the diamond. However, this method still has the problem of difficulty in accurately controlling the thickness of the transition layer.
[0011] In summary, existing copper-based diamond composite material preparation technologies still face problems such as poor interfacial bonding, complex process control, difficulty in achieving both high thermal conductivity and high densification, and poor thermal conductivity at high temperatures. There is an urgent need to develop more efficient and stable interfacial control and sintering molding processes. Summary of the Invention
[0012] The purpose of this invention is to address the shortcomings of the prior art by providing a method for preparing a copper-based diamond composite heat dissipation material, thereby obtaining a high-performance copper-based diamond composite material and effectively solving the thermal stress problem in the heat dissipation process of semiconductor devices.
[0013] To solve the above technical problems, the technical solution adopted by the present invention is as follows: A method for preparing a copper-diamond composite heat dissipation material, comprising 50-95 vol% diamond and 5-50 vol% copper, wherein the copper particle size is 2-50 μm, and the preparation method includes the following steps: (1) Roughening treatment of diamond Weigh diamond particles of single or multiple sizes and combine them, then etch them with plasma beam to obtain roughened diamond and expose more (100) crystal planes. (2) Diamond plating A copper protective layer is deposited on the roughened diamond surface obtained in step (1) using a magnetron sputtering device that integrates acoustic resonance components; (3) Powder mixing Weigh out copper powder, mix it with coated diamond powder using an acoustic resonance mixer, and place the mixed powder in a boron nitride crucible. (4) Powder pretreatment: The mixed powder in the boron nitride crucible was vacuum heat-treated using a tube furnace to remove organic matter and adsorbed gas from its surface, and the mixed powder was pre-pressed to form a green body. (5) Sintering: The green body obtained in step (4) is subjected to high temperature and high pressure sintering. The pressure is 2~6GPa, the temperature is 800~1700℃, and the holding time is 10~60min. The sintering sequence is as follows: first pressurize to the set pressure → then heat to the target temperature → hold at the temperature → cool down naturally → depressurize, and the temperature is measured in real time by the built-in thermocouple during the heating process; (6) Discharge After the high-temperature and high-pressure sintering equipment in step (5) is cooled and depressurized, the sintered copper-based diamond composite block is taken out to obtain the high-performance copper-based diamond composite material.
[0014] In step (4), during vacuum heat treatment, the vacuum level is higher than 10. -2 Pa, temperature 500-1000 ℃, holding time 10-30 min, heating rate 10 ℃ / min; In step (4), during pre-pressing, a hydraulic press is used to apply pressure of 10-200 MPa, and the pressure holding time is 5-20 minutes.
[0015] In step (1), plasma beam etching uses argon ions or oxygen atoms to treat the surface of diamond. The power is 50~500 W, the treatment time is 5-30 min, the gas pressure is 10~100 Pa, and after the treatment is completed, the diamond particles are cleaned with deionized water.
[0016] In step (2), diamond and copper are placed in a mixing tank and mixed evenly by acoustic resonance. The resonance frequency is 40-60 Hz, the time is 5-60 min, the acceleration is 5-120 g, and the proportion of diamond during mixing is 50-95 vol% and the proportion of copper is 5-50 vol%.
[0017] In step (3), the copper powder has a purity of ≥99% and a particle size of 2~5 μm.
[0018] In step (1), the diamond raw material has a purity of ≥99%, a particle size of 20~700 μm, and a nitrogen content of <120 ppm.
[0019] The beneficial effects of this invention are: (1) This invention discloses a method for preparing a copper-diamond composite heat dissipation material, which can produce a high-performance copper-diamond composite material. The composite bulk material includes 50-95 vol% diamond and 5-50 vol% copper, and the particle size of the diamond particles is in the range of 20-700 μm, while the copper particle size is 2-50 μm. Through optimized preparation process, the obtained bulk material has excellent comprehensive properties: relative density ≥98%, room temperature thermal conductivity ≥550 W / (m·K), and thermal expansion coefficient can be controlled within 2×10. -6Up to 1×10 -5 K -1 Between these two types of materials, the thermal conductivity at 100℃ is ≥500 W / (m·K). It not only has outstanding thermal conductivity and mechanical properties, but its coefficient of thermal expansion is also matched with that of semiconductor materials. It can effectively solve the thermal stress problem in the heat dissipation process of semiconductor devices, and ensure the stable operation of devices in high-temperature environments. It has important application value in the field of semiconductor heat dissipation.
[0020] (2) Roughening the diamond can increase its contact area with the metal coating, increase the bonding force between the two, and make the coating less likely to fall off. Compared with traditional electroplating and chemical plating, the magnetron sputtering device with integrated acoustic resonance device can achieve uniform coating on the diamond surface and can precisely adjust the coating thickness by adjusting the parameters to achieve the purpose of designing the transition layer thickness.
[0021] (3) Compared with traditional melting and infiltration, hot pressing sintering, and discharge plasma sintering, high temperature and high pressure can be sintered under higher pressure. High pressure can stabilize diamond and prevent diamond from graphitizing. Graphitization of diamond will reduce the thermal conductivity of the material.
[0022] (4) Compared with hot pressing sintering and discharge plasma sintering, the high temperature and high pressure method can prepare copper-based diamond composite heat dissipation materials above the melting point of copper, which can ensure that copper has sufficient fluidity, making its distribution in the composite sheet more uniform, and can effectively reduce the presence of pores in the material. Both are beneficial to obtaining composite materials with high thermal conductivity. Attached Figure Description
[0023] Figure 1 This invention relates to the wettability of diamond and copper (a), phase diagram (b), and bonding schematic diagram (c). Detailed Implementation
[0024] The following specific embodiments illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification.
[0025] This invention provides a method for preparing a copper-diamond composite heat dissipation material. The copper-diamond composite heat dissipation material comprises 50-95 vol% diamond and 5-50 vol% copper, and the copper particle size is 2-50 μm. The preparation method includes the following steps: (1) Roughening treatment of diamond Weigh diamond particles of single or multiple sizes and combine them, then etch them with plasma beam to obtain roughened diamond and expose more (100) crystal planes. The diamond raw material has a purity of ≥99%, a particle size of 20~700 μm, and a nitrogen content of <120 ppm; Plasma beam etching uses argon ions or oxygen atoms to treat the surface of diamond. The power is 50~500 W to avoid insufficient etching due to too low power and damage to the crystal lattice due to too high power. The treatment time is 5-30 min and the gas pressure is 10~100 Pa. After the treatment is completed, the diamond particles are cleaned with deionized water.
[0026] (2) Diamond plating A copper protective layer is deposited on the roughened diamond surface obtained in step (1) using a magnetron sputtering device that integrates acoustic resonance components; Diamond and copper are placed in a mixing tank and mixed uniformly through acoustic resonance at a frequency of 40–60 Hz for 5–60 minutes, with an acceleration of 5–120 g (where g is the gravitational acceleration of 9.8 m / s²). 2 When mixing, the diamond content is 50~95 vol% and the copper content is 5~50 vol%.
[0027] (3) Powder mixing Weigh out copper powder and mix it with coated diamond powder using an acoustic resonance mixer. Place the mixed powder in a boron nitride crucible. The copper powder has a purity of ≥99% and a particle size of 2~5 μm.
[0028] (4) Powder pretreatment: The mixed powder in the boron nitride crucible was vacuum heat-treated using a tube furnace to remove organic matter and adsorbed gas from its surface, and the mixed powder was pre-pressed to form a green body. During vacuum heat treatment, the vacuum level is higher than 10. -2 Pa, temperature 500-1000 ℃, holding time 10-30 min, heating rate 10 ℃ / min; During pre-pressing, a hydraulic press is used to apply pressure of 10-200 MPa, and the pressure holding time is 5-20 minutes.
[0029] (5) Sintering: The green body obtained in step (4) is subjected to high temperature and high pressure sintering. The pressure is 2~6GPa, the temperature is 850~1500℃, and the holding time is 1~60min. The sintering sequence is as follows: first pressurize to the set pressure → then heat to the target temperature → hold at the temperature → cool down naturally → depressurize, and the temperature is measured in real time by the built-in thermocouple during the heating process; (6) Discharge After the high-temperature and high-pressure sintering equipment in step (5) is cooled and depressurized, the sintered copper-based diamond composite block is taken out to obtain the high-performance copper-based diamond composite material.
[0030] The following description, in conjunction with specific embodiments, further illustrates the present invention, and the specifications and sources of raw materials are standardized.
[0031] Diamond: MBD-4 type synthetic diamond produced by a diamond company in Henan Province was selected. The purity was 99.5%, the nitrogen content was 80 ppm, the single particle size was 300 μm, the volume percentage was 80 vol%, the particle morphology was irregular polyhedron, and there was no obvious impurity agglomeration.
[0032] Copper powder: purchased from a non-ferrous metal materials company, purity 99.9%, particle size 3μm, BET specific surface area 1.2 m². 2 / g, good dispersibility, no obvious agglomeration, volume percentage 20 vol.
[0033] Auxiliary materials: boron nitride crucible (purity 99.9%, high temperature resistance ≥1800℃, pressure resistance ≥10 GPa), argon gas (purity 99.99%, water content <10 ppm).
[0034] Coating material: Chromium target (99.95% purity, Φ50 mm × 3 mm), used for magnetron sputtering to coat a protective layer.
[0035] The general process parameters are as follows: Vacuum heat treatment: A tube vacuum furnace (model GSL-1700X) was used, with a vacuum degree of 5×10⁻⁶. -3 Pa (above 10) -2 (Pa requirement), heating rate 10 ℃ / min (fixed), holding temperature 800 ℃ (intermediate value between 500-1000 ℃, taking into account both impurity removal and energy saving), holding time 20 min (intermediate value between 10-30 min, to fully remove organic matter and adsorbed gas).
[0036] Pre-pressing: Use a hydraulic press with a pressure of 50 MPa (10-200 MPa intermediate value to avoid the billet being too loose due to too low pressure and the particles being broken due to too high pressure), and a holding time of 5 min to produce a cylindrical billet with a diameter of 20 mm and a thickness of 5 mm, and a relative density of ≥65%.
[0037] High-temperature and high-pressure sintering: A six-sided high-pressure sintering equipment is used, with a uniform pressure of ≤6 GPa. The sintering sequence strictly follows the procedure of "first pressurizing to the set pressure (pressurization rate 1 GPa / min) → then heating to the target temperature (heating rate 50 ℃ / min) → holding at the temperature → natural cooling (cooling rate 10 ℃ / s) → depressurizing (depressurization rate 0.5 GPa / min)". The temperature is measured in real time by built-in thermocouples during the heating process (temperature measurement accuracy ±5 ℃).
[0038] The general testing methods and equipment are as follows: Relative density: Archimedes' displacement method was used (electronic balance accuracy 0.1 mg, deionized water as medium), and the average value was taken after 3 tests, with an error of ±0.2%; Thermal conductivity (room temperature +100℃): A Netzsch LFA 447Nanoflash laser thermal conductivity meter was used. The sample size was Φ12.6 mm × 2 mm. A graphite layer (thickness <10 μm) was sprayed on the sample before testing. The error was ±2%. Coefficient of thermal expansion: Tested using a thermomechanical analyzer, model Netzsch DIL 402EP, with a test temperature range of 25-500℃, a heating rate of 5℃ / min, and an error of ±5×10. -7 K -1 ; Diamond graphitization rate: Calculated using an X-ray diffractometer (Bruker D8 Advance, Cu Kα radiation, scanning range 20°-80°) based on the diffraction intensity of the diamond (111) crystal plane and the graphite (002) crystal plane, with an error of ±0.1%. Microstructure characterization: A scanning electron microscope (ZEISS Sigma 300) was used to observe the cross-sectional morphology and coating uniformity of the samples, and an energy dispersive spectroscopy (EDS) instrument was used to analyze the elemental distribution. Comparative Example 1
[0039] No pretreatment + SPS sintering (benchmark comparison group) This comparative example serves as the basic reference for the entire process, verifying the extreme performance of "no plasma etching roughening + no magnetron sputtering coating" + "conventional SPS sintering", clarifying the incremental value of high temperature and high pressure sintering and pretreatment processes. All auxiliary processes (mixing, vacuum heat treatment, pre-pressing) are consistent with other examples to ensure the fairness of the comparison.
[0040] The process steps are as follows: (1) Powder mixing: 80 vol% diamond particles (approximately 12.6 g) and 20 vol% copper powder (approximately 3.1 g) were placed in an acoustic resonance mixer. The frequency was set to 50 Hz, the acceleration to 60 g, and the mixing time to 30 min. Argon gas was introduced during the mixing process (flow rate 5 L / min) to prevent oxidation of the copper powder. The uniformity of the mixed powder was ≥95% (verified by color difference method). (2) Powder pretreatment: The mixed powder is loaded into a boron nitride crucible (50 mL volume), placed in a tube vacuum furnace, and after closing the furnace door, a vacuum of 5 × 10⁻⁶ is drawn. -3 Pa, start the heating program, raise to 800℃ at 10℃ / min, and hold for 20 min before naturally cooling to room temperature. Take out the powder and observe that there is no clumping or oxidation discoloration. (3) Pre-pressing: Pour the pre-treated powder into a cylindrical mold, place it in a hydraulic press, apply 50MPa pressure and hold for 5 minutes, and after demolding, obtain a blank with no cracks or slag on the surface. (4) SPS sintering: The blank is placed in a graphite mold in a discharge plasma sintering furnace, vacuum is drawn, and the parameters are set as follows: pressure 50 MPa, temperature 950 ℃, holding time 10 min, heating rate 50 ℃ / min. After sintering, it is naturally cooled to room temperature. (5) Unloading and post-processing: Take out the sintered block, use laser to cut out a circular piece with a diameter of 12.6 mm, grind the surface with a diamond grinding wheel, and polish it with polishing paste to remove the oxide layer and graphite contamination. After grinding, the surface roughness Ra≤0.1 μm, and finally obtain a composite block with a size of Φ12.6 mm×3 mm.
[0041] The above process involves no pretreatment and is prepared solely through physical mixing and conventional sintering. It has low process complexity, controllable cost, and conforms to the basic process logic of industrial mass production. The SPS sintering temperature is 950 ℃ (lower than the melting point of copper 1083 ℃) to avoid excessive melting of copper and loss. The pressure is 50 MPa (far below the 6 GPa high temperature and high pressure range). The particle bonding is mainly achieved by the Joule heating of pulsed current.
[0042] The performance test results and analysis are as follows: The relative density test result was 95.2%, lower than the specified requirement of ≥98%, because the SPS pressure was insufficient to eliminate powder gaps and pores; the room temperature thermal conductivity was 480 W / (m·K), lower than the specified requirement of ≥550 W / (m·K), because weak interfacial bonding and high porosity (approximately 4.8%) led to high thermal resistance; the thermal conductivity at 100℃ was 435 W / (m·K), decreasing slightly with increasing temperature, because interfacial thermal resistance is temperature-sensitive, and heat conduction efficiency decreases at high temperatures; the coefficient of thermal expansion (25-500℃) was 8.5×10⁻⁶.-6 K -1 The high coefficient of thermal expansion is due to the uneven distribution of copper and poor consistency of thermal expansion. The graphitization rate of diamond is 3.2%, which is relatively high. This is because the local temperature is too high during SPS sintering, and the diamond undergoes partial phase transformation. Microscopic SEM observation shows that diamond particles are detached from the cross-section, the gap between the copper matrix and diamond is obvious, the pores are unevenly distributed, and there is no effective bonding at the interface. The main bonding is mechanical interlocking, resulting in poor overall performance. Comparative Example 2
[0043] There is a pretreatment + SPS sintering group, namely the pretreatment effect verification group. This comparative example 2 keeps the sintering method as SPS and only adds the "plasma etching roughening + magnetron sputtering coating" pretreatment process. Compared with comparative example 1, it verifies the effect of pretreatment on interface bonding and performance improvement, and provides a performance reference for the "pretreatment + conventional sintering" example for the high temperature and high pressure embodiment.
[0044] In this embodiment, preprocessing details are added, and the rest is the same as in Comparative Example 1. The process steps are as follows: (1) Diamond roughening treatment (plasma etching): Diamond particles were placed in a plasma etching machine (model PT-300), and argon gas (purity 99.99%, flow rate 60 sccm) was introduced. The parameters were set as follows: power 200 W, etching time 15 min, reaction chamber pressure 50 Pa. After etching, the diamond was removed. The surface roughness Ra increased from the initial 0.05 μm to 0.3 μm, and the (100) crystal plane exposure ratio increased from 30% to 65% (XRD verification). (2) Diamond coating (magnetron sputtering): Using a magnetron sputtering system with integrated acoustic resonant components, model JGP-560, etched diamond particles were uniformly spread on the sample stage with a thickness ≤5 mm. Argon gas was introduced at a flow rate of 50 sccm. The parameters were set as follows: acoustic resonant frequency 20 Hz, acceleration 30 g, target-substrate distance 80 mm, sputtering power 120 W, and coating time 20 min. A uniform chromium coating with a thickness of 1.2 μm was finally formed on the diamond surface. The step test showed an error of ±0.1 μm, and the coating uniformity was ≤±5%. The results were verified by EDS surface scanning. (3) Powder mixing: Add chromium-plated diamond particles during mixing, and keep the other parameters the same as in Comparative Example 1; (4) Powder pretreatment: Same as Comparative Example 1; (5) Pre-compression: Same as Comparative Example 1; (6) SPS sintering: Same as comparative example 1; (7) Discharge and post-processing: Same as Comparative Example 1.
[0045] The above pretreatment process specifically addresses the interface bonding problem between diamond and copper: plasma etching increases the surface roughness and active sites of diamond through high-energy bombardment with argon ions; magnetron sputtering chromium plating forms a transition layer, where chromium and copper can form a solid solution and form weak chemical bonds with diamond through interfacial reactions, thus improving the interfacial bonding force; the sintering method remains SPS at a pressure of 50 MPa, forming a comparative logic of "same pretreatment, different sintering pressure" with the high-temperature and high-pressure example, highlighting the dominant role of pressure on performance.
[0046] The performance test results and analysis are as follows: The relative density test result was 96.8%, an improvement of 1.6% compared to Comparative Example 1, due to improved interfacial bonding and reduced interfacial gaps caused by pretreatment; the room temperature thermal conductivity was 530 W / (m·K), an improvement of 10.4% compared to Comparative Example 1, approaching the standard limit of ≥550 W / (m·K), and the interfacial thermal resistance decreased from 2×10 -8 W -1 ·m 2 K decreased to 1.5 × 10 -8 W -1 ·m 2 The thermal conductivity at 100℃ is 490 W / (m·K), an increase of 12.6% compared to Comparative Example 1, indicating improved interfacial stability at high temperatures; the coefficient of thermal expansion (25-500℃) is 7.2×10⁻⁶. - 6 K -1 Compared to Comparative Example 1, the thermal expansion rate was reduced by 15.3%, as the coating suppressed the free expansion of copper and improved the uniformity of thermal expansion. The graphitization rate of diamond was 2.8%, which was reduced by 12.5% compared to Comparative Example 1. The chromium coating has a certain protective effect on diamond and suppresses the graphitization phase transformation. Microscopic morphology (SEM) observation showed that the diamond particles in the fracture surface were tightly bonded to the copper matrix with no obvious gaps. A small amount of diamond cleavage fracture was observed. The pretreatment effectively improved the interfacial bonding, and the fracture mode changed from "interfacial debonding" to "diamond cleavage + copper matrix ductile fracture". Example 1
[0047] With pretreatment +3 GPa / 1100 ℃ / 10 min, this example tests the combination of low pressure range below 6 GPa (3 GPa) and temperature above copper melting point (1100℃) to verify the basic performance level under low pressure, high temperature and high pressure conditions, adapt to low pressure equipment conditions, such as small high pressure sintering machines, and explore the synergistic effect of "lower pressure limit + upper temperature limit".
[0048] The pretreatment process is the same as in Comparative Example 2, but the sintering parameters are adjusted. The specific process steps are as follows: (1) Diamond roughening treatment: Same as Comparative Example 2, plasma etching, 200 W, 15 min, 50 Pa; (2) Diamond coating: Same as Comparative Example 2, magnetron sputtering chromium plating, 50 Hz, 60 g, 20 min, coating thickness 1.2 μm; (3) Powder mixing: Same as comparative example 2; (4) Powder pretreatment: Same as Comparative Example 2; (5) Pre-compression: Same as comparative example 2, 50 MPa, holding pressure for 5 min, the relative density of the billet is 66%; (6) High-temperature and high-pressure sintering: The six-sided high-pressure sintering equipment has the following parameters: pressure 3 GPa, pressure increase rate 1 GPa / min, holding pressure for 1 min and then heating; temperature 1100℃, which is 17℃ higher than the melting point of copper to ensure the fluidity of the copper melt; holding temperature for 10 min, a short holding time to avoid excessive oxidation of copper. (7) Discharge and post-processing: After cooling and depressurization, the block is taken out and the surface oxide layer is polished with a diamond grinding wheel. The thickness is ≤0.5mm. The final size is Φ12.6 mm×3.8 mm. There are no cracks or deformations in the appearance.
[0049] The pressure is 3 GPa, which meets the upper limit of pressure for small high-pressure equipment and reduces equipment costs; the temperature is 1100℃, where copper is in a molten state with good fluidity, which can fully fill the gaps between diamonds; the holding time is 10 min (relatively short), because the filling rate of copper melt is slow under low pressure, and excessive holding time will cause copper to volatilize or oxidize, thus balancing the filling effect and performance stability.
[0050] Performance test results and analysis: The relative density test result was 97.8%, an increase of 1.0% compared to Comparative Example 2. High pressure facilitated the penetration of the copper melt into the diamond interstices, reducing the porosity to 2.2%. The room temperature thermal conductivity was 570 W / (m·K), an increase of 7.5% compared to Comparative Example 2, meeting the requirement of ≥550 W / (m·K). The diamond-copper interface showed a tighter bond, further reducing thermal resistance. The thermal conductivity at 100℃ was 530 W / (m·K), an increase of 8.2% compared to Comparative Example 2. The interface thermal stability was good at high temperatures, with no significant increase in thermal resistance. The coefficient of thermal expansion (25-500 ℃) was 6.5 × 10⁻⁶. -6 K -1 Compared to Comparative Example 2, the copper content was reduced by 9.7%. High pressure refined the copper grains and further reduced the coefficient of thermal expansion. The graphitization rate of diamond was 1.2%, a decrease of 57.1% compared to Comparative Example 2. 3 GPa pressure can effectively stabilize the diamond crystal structure and inhibit graphitization. Microscopic morphology (SEM) observation showed that the copper matrix was continuously distributed in the cross-section, the diamond particles were completely wrapped by copper with no exposed areas, there was no obvious boundary between the coating and copper and diamond, and the copper melt fully filled the gaps. The pretreatment + low pressure and high temperature synergistic effect resulted in excellent interface fusion. Example 2
[0051] There is a pretreatment + 4 GPa / 1200 ℃ / 20 min (medium pressure + optimized temperature group). This example uses a combination of medium pressure below 6 GPa and optimal temperature of 1200℃, which takes into account both pressure stability and temperature promotion effect. As the mainstream working condition reference for industrial mass production, it verifies the comprehensive performance advantages of "medium pressure + optimized temperature + medium holding time".
[0052] In this embodiment, the pretreatment is the same as in Comparative Example 2, but the sintering parameters are adjusted. The specific process steps are as follows: (1) Diamond roughening treatment: same as comparative example 2; (2) Diamond coating: Same as Comparative Example 2; (3) Powder mixing: Same as comparative example 2; (4) Powder pretreatment: Same as comparative example 2; (5) Pre-compression: Same as Comparative Example 2, the relative density of the billet is 67%; (6) High-temperature and high-pressure sintering: The six-sided high-pressure sintering equipment has the following parameters: pressure 4 GPa, pressure increase rate 1 GPa / min, pressure holding for 1 min; temperature 1200℃, holding for 20 min, with a medium holding time to ensure sufficient diffusion and fusion at the interface. (7) Discharge and post-processing: Same as in Example 1, the final block size is Φ12.6 mm×3.9 mm, and the surface flatness Ra≤0.08 μm.
[0053] The pressure is in the medium pressure range of 4 GPa, which can effectively stabilize diamond and promote copper filling without excessive equipment costs; the temperature is 1200℃, and the copper melt has the best fluidity (viscosity drops to 0.002 Pa·s), which can quickly fill the gaps between diamonds; the holding time is 20 min, which matches the diffusion rate of copper and chromium, promotes the formation of a continuous diffusion layer at the interface, and avoids insufficient interface fusion caused by short holding time.
[0054] The performance test results and analysis are as follows: The relative density test result was 98.6%, meeting the requirement of ≥98%, with a porosity of only 1.4%, indicating that the copper melt completely filled the diamond interstitial spaces and interfacial gaps; the room temperature thermal conductivity was 650 W / (m·K), an improvement of 14.0% compared to Example 1, due to the reduction of interfacial thermal resistance to 8×10⁻⁶. -9 W -1 ·m 2 • K, ensuring unobstructed heat conduction path; thermal conductivity at 100℃ is 610 W / (m·K), a 15.1% improvement over Example 1, meeting the requirement of ≥500 W / (m·K) thermal conductivity at 100℃, with sufficient performance redundancy; coefficient of thermal expansion (25-500℃) is 5.2 × 10⁻⁶. -6 K-1 Compared to Example 1, the graphitization rate was reduced by 20.0%. High pressure made the bonding between diamond and copper tighter and improved the synergistic effect of thermal expansion. The graphitization rate of diamond was 0.7%, which was reduced by 41.7% compared to Example 1. The synergistic effect of 4 GPa pressure + 1200℃ temperature completely suppressed the graphitization trend of diamond. Microscopic morphology (SEM) observation showed that there were no obvious pores in the fracture surface, the cleavage fracture rate of diamond particles was ≥80%, the copper matrix showed ductile fracture characteristics (clear dimples), the interfacial bonding strength exceeded the self-strength of diamond and copper, and the fracture mode was mainly "diamond cleavage + copper matrix dimple fracture". Example 3
[0055] With pretreatment +5 GPa / 1300 ℃ / 30 min (medium-high pressure + high temperature group), this embodiment tests the combination of medium-high pressure below 6 GPa and high temperature of 5 GPa and 1300℃, which are the enhancement parameters before the pressure limit is reached. It explores the performance improvement potential in the 6 GPa range and is suitable for high-end application scenarios with high thermal conductivity requirements, such as heat dissipation of high-power electronic devices.
[0056] The pretreatment process is the same as in Comparative Example 2, but the sintering parameters are adjusted. The specific process steps are as follows: (1) Diamond roughening treatment: same as comparative example 2; (2) Diamond coating: Same as Comparative Example 2; (3) Powder mixing: Same as comparative example 2; (4) Powder pretreatment: Same as comparative example 2; (5) Pre-compression: Same as Comparative Example 2, the relative density of the billet is 68%; (6) High-temperature and high-pressure sintering: Six-sided high-pressure sintering equipment, parameter settings: pressure 5 Gpa, pressure increase rate 1 GPa / min, pressure holding for 1 min; temperature 1300℃ (217℃ above the copper melting point to further improve copper fluidity), holding for 30 min, extending the holding time to enhance interfacial diffusion and diamond framework formation. (7) Discharge and post-processing: Same as in Example 1, the final block size is Φ12.6 mm×3.9 mm, the surface is free of oxidation color, and the microstructure is uniform.
[0057] Above, a pressure of 5 GPa is in the medium-high pressure range, close to the upper limit of 6 GPa, where the crystal structure stability of diamond reaches its optimal level, while also promoting slight bonding between diamond particles; a temperature of 1300℃ reduces the viscosity of copper melt to its lowest level, allowing it to penetrate into the tiny gaps (≤1 μm) between diamond particles; a holding time of 30 min provides a sufficiently long time for the chromium plating layer on the diamond surface to completely diffuse into the copper matrix, while also promoting secondary crystallization between diamond particles, forming a local diamond framework (EDS verification shows continuous carbon signal).
[0058] The performance test results and analysis are as follows: The relative density test result was 99.2%, an improvement of 0.6% compared to Example 2, with a porosity of only 0.8%, reaching a near-fully dense state; the room temperature thermal conductivity was 695 W / (m·K), an improvement of 6.9% compared to Example 2. Due to the local formation of a diamond framework, the heat conduction path changed from "copper-plating-diamond" to "diamond-diamond-copper", significantly reducing thermal resistance; the thermal conductivity at 100℃ was 660 W / (m·K), an improvement of 8.2% compared to Example 2. The diamond framework exhibited excellent thermal stability at high temperatures, with a thermal conductivity decay rate of only 5.0%; the coefficient of thermal expansion (25-500℃) was 4.3×10⁻⁶. -6 K -1 Compared to Example 2, the thermal expansion is reduced by 17.3%. The diamond framework suppresses the thermal expansion of copper, and the coefficient of thermal expansion is close to the ideal range required for electronic packaging (3-5×10). -6 K -1 The graphitization rate of diamond was 0.4%, which was 42.9% lower than that of Example 2. The 5GPa high pressure effectively suppressed the graphitization phase transformation at high temperature, and the diamond structure was stable. Microscopic morphology (SEM) observation showed that a continuous bonding interface was formed between diamond particles (without copper filling area), the copper matrix was uniformly distributed in the gaps between the diamond skeleton, the number of dimples increased, local diamond skeletons were formed, the thermal conductivity was greatly improved, and the toughness of the material was improved simultaneously. Example 4
[0059] With pretreatment + 6 GPa / 1400 ℃ / 15 min (pressure limit + high temperature group), this example uses the combination of a pressure limit of 6 GPa after shrinkage and a high temperature of 1400℃ to test the optimal parameter combination and ultimate performance within the 6 GPa range. As a benchmark solution for high-performance products, it verifies the synergistic effect of "pressure limit + high temperature + moderate heat preservation time" to maximize the performance.
[0060] The pretreatment process is the same as in Comparative Example 2, but the sintering parameters are adjusted. The specific process steps are as follows: (1) Diamond roughening treatment: same as comparative example 2; (2) Diamond coating: Same as Comparative Example 2; (3) Powder mixing: Same as comparative example 2; (4) Powder pretreatment: Same as comparative example 2; (5) Pre-compression: Same as Comparative Example 2, the relative density of the billet is 69%; (6) High-temperature and high-pressure sintering: Six-sided high-pressure sintering equipment, parameter settings: pressure 6 GPa, upper limit after shrinkage, pressure increase rate 1 GPa / min, holding pressure 1 min; temperature 1400℃, 317℃ above the copper melting point, copper melt has the best fluidity; holding temperature 15 min, moderate holding time, to avoid excessive copper volatilization and diamond lattice damage at high temperature. (7) Discharge and post-processing: Same as in Example 1, the final block size is Φ12.6 mm×4.0 mm, with the best overall performance.
[0061] The pressure is 6 GPa, the upper limit; above 6 GPa, a distinct diamond framework can be formed. In this embodiment, a continuous diamond framework is formed at 6 GPa, and there is no risk of excessive phase transformation of diamond; the temperature is 1400℃, the copper melt completely wets the diamond surface, and the interface wetting angle is close to 0°; the holding time is 15 min, which balances "interface diffusion fusion" and "performance stability": too long (>20 min) will lead to copper volatilization and diamond lattice defects, while too short (<10 min) will result in insufficient formation of the diamond framework.
[0062] The performance test results and analysis are as follows: The relative density test result was 99.5%, an improvement of 0.3% compared to Example 3, with a porosity of only 0.5%, achieving a fully dense state (relative density ≥ 99.5%); the room temperature thermal conductivity was 720 W / (m·K), an improvement of 3.6% compared to Example 3, and the highest value in the 6 GPa range. The continuous diamond framework provides an efficient heat conduction path, and the interfacial thermal resistance is reduced to 5 × 10⁻⁶. -9 W -1 ·m 2 The thermal conductivity at 100℃ is 685 W / (m·K), an improvement of 3.8% compared to Example 3, with a thermal conductivity decay rate of only 4.9%, demonstrating excellent high-temperature stability; the coefficient of thermal expansion (25-500℃) is 3.8 × 10⁻⁶. -6 K -1 Compared to Example 3, the thermal expansion rate was reduced by 11.6%, falling entirely within the ideal thermal expansion range for electronic packaging, and exhibiting excellent compatibility with semiconductor materials (such as silicon). XRD showed that the graphitization rate of diamond was 0.2%, a reduction of 50.0% compared to Example 3. The 6GPa high pressure completely suppressed graphitization at high temperatures, and the diamond crystal structure remained undamaged. Microscopic morphology (SEM) observation showed that a continuous framework structure was formed between diamond particles (continuous carbon signal, no copper signal in EDS), and the copper matrix uniformly filled the gaps in the framework. The fracture dimples were dense and uniform. The continuous diamond framework + fully dense copper matrix achieved a synergistic performance of "high thermal conductivity + low expansion + high toughness". Example 5
[0063] The example includes a pretreatment process of +3 GPa / 1400 ℃ / 20 min (low pressure + high temperature group). This example uses a fixed low pressure of 3 GPa and increases the temperature to 1400℃ to verify the performance compensation effect of high temperature under low pressure conditions. It is suitable for scenarios with only low pressure equipment but certain performance requirements and explores the parameter optimization space of "low pressure + high temperature".
[0064] The pretreatment process is the same as in Comparative Example 2, but the sintering parameters are adjusted. The specific process steps are as follows: (1) Diamond roughening treatment: same as comparative example 2; (2) Diamond coating: Same as Comparative Example 2; (3) Powder mixing: Same as comparative example 2; (4) Powder pretreatment: Same as comparative example 2; (5) Pre-compression: Same as Comparative Example 2 (relative density of billet 66%); (6) High temperature and high pressure sintering: Six-sided high pressure sintering equipment, parameter settings: pressure 3 GPa, temperature 1400℃, holding time 20 min; (7) Discharge and post-processing: Same as in Example 1, final block size Φ12.6 mm×3.8 mm.
[0065] The pressure of 3 GPa is low pressure, resulting in low equipment cost; the temperature of 1400℃ is high temperature, which improves the fluidity of the copper melt and compensates for insufficient filling under low pressure; the holding time of 20 min is 10 min longer than in Example 1, ensuring that the copper melt fully penetrates the diamond gaps under low pressure and avoiding incomplete filling due to insufficient pressure.
[0066] The performance test results and analysis are as follows: The relative density test result was 98.1%, an increase of 0.3% compared to Example 1. High temperature enhanced the fluidity of the copper melt, resulting in a better filling effect than Example 1 (3 GPa / 1100℃). The room temperature thermal conductivity was 600 W / (m·K), an increase of 5.3% compared to Example 1. High temperature promoted interfacial diffusion and reduced thermal resistance, but due to the absence of a diamond framework, the thermal conductivity was lower than that of the medium-high pressure group. The thermal conductivity at 100℃ was 565 W / (m·K), an increase of 6.6% compared to Example 1. The interfacial stability was good at high temperatures, but the thermal conductivity was still lower than that of Examples 2-4. The coefficient of thermal expansion (25-500℃) was 5.8 × 10⁻⁶. -6 K -1Compared to Example 1, the thermal expansion coefficient was reduced by 10.8%. High temperature refined the copper grains and reduced the thermal expansion coefficient, but it was still higher than that of the medium-high pressure group. The graphitization rate of diamond was 0.9%, which was 25.0% lower than that of Example 1. The low pressure at high temperature had a limited effect on the stability of the diamond structure, and the graphitization rate was slightly higher than that of the medium-high pressure group. Microscopic morphology (SEM) observation showed that the copper matrix was fully filled with a small number of micropores (≤0.5 μm). The diamond particles were tightly bonded to the copper. High temperature effectively compensated for the deficiency of low pressure, but no diamond skeleton was formed, and the performance was still lower than that of the medium-high pressure combination. Example 6
[0067] There is a pretreatment + 6 GPa / 900 ℃ / 40 min (pressure upper limit + temperature below copper melting point group). In this example, a fixed pressure upper limit of 6 GPa is used, and the temperature is reduced to below the copper melting point, that is, 900℃, to verify the performance protection effect of high pressure under low temperature conditions. It is suitable for special working conditions that are sensitive to temperature (such as avoiding excessive copper oxidation) and explores the feasibility of the parameter combination of "high pressure + low temperature".
[0068] The pretreatment process is the same as in Comparative Example 2, but the sintering parameters are adjusted. The specific process steps are as follows: (1) Diamond roughening treatment: same as comparative example 2; (2) Diamond coating: Same as Comparative Example 2; (3) Powder mixing: Same as comparative example 2; (4) Powder pretreatment: Same as comparative example 2; (5) Pre-compression: Same as Comparative Example 2, the relative density of the billet is 69%; (6) High-temperature and high-pressure sintering: Six-sided high-pressure sintering equipment, parameter settings: pressure 6 GPa, temperature 900℃ (183℃ lower than the melting point of copper), holding time 40 min, extending the holding time to compensate for the insufficient fluidity of copper. (7) Discharge and post-processing: Same as in Example 1, final block size Φ12.6mm×3.9mm.
[0069] The pressure is capped at 6 GPa. High pressure promotes plastic deformation and diffusion bonding of copper particles, compensating for the lack of melt flow of copper at low temperatures. The temperature is 900℃ (low temperature) to avoid excessive oxidation and volatilization of copper, making it suitable for scenarios with strict oxygen content requirements. The holding time is 40 min, which is long enough for the copper particles to achieve densification through solid-phase diffusion under high pressure, while also promoting the bonding between the coating and the substrate.
[0070] The performance test results and analysis are as follows: The relative density test result was 98.8%, a decrease of 0.7% compared to Example 4. High pressure promoted solid-phase diffusion densification, but there was no melt flow, and the porosity was slightly higher than that of Example 4. The room temperature thermal conductivity was 580 W / (m·K), a decrease of 19.4% compared to Example 4. Because copper is in the solid phase, the thermal conductivity is lower than that of the sample filled with molten copper, and no diamond framework was formed. The thermal conductivity at 100℃ was 540 W / (m·K), a decrease of 21.2% compared to Example 4, which meets the claims, but the performance is lower than that of the group above the melting point of copper. The coefficient of thermal expansion (25-500℃) was 6.1×10⁻⁶. -6 K -1 The coefficient of thermal expansion of solid copper was 86.8% higher than that of Example 4, indicating that the coefficient of thermal expansion of solid copper was higher than that of the grain-refined sample filled with molten copper. The graphitization rate of diamond was 0.6%, which was 200% higher than that of Example 4. The diamond structure was stable at low temperature, but there was no interface reaction promoted by high temperature, and the graphitization rate was slightly higher. Microscopic morphology (SEM) observation showed that the copper matrix exhibited solid-phase diffusion bonding characteristics, with clear particle boundaries. The diamond particles were tightly wrapped by copper without obvious gaps. High pressure achieved solid-phase densification, but the performance was limited by the phase state of copper and was lower than that of the temperature group above the melting point of copper. Example 7
[0071] No pretreatment + 4 GPa / 1200 ℃ / 20 min (no pretreatment + medium pressure high temperature group): This example uses the medium pressure high temperature parameters of Example 2, 4 GPa / 1200 ℃ / 20 min, and cancels the pretreatment process. Compared with Example 2, it verifies the necessity of pretreatment under high pressure conditions below 6 GPa and clarifies the core contribution of pretreatment to interface bonding and performance.
[0072] In this embodiment, no pretreatment is required, and the rest is the same as in Embodiment 2. The specific process steps are as follows: (1) Powder mixing: Same as Comparative Example 1, diamond and copper powder were directly mixed without pretreatment; (2) Powder pretreatment: Same as Comparative Example 1; (3) Pre-compression: Same as Comparative Example 1, the relative density of the billet is 65%; (4) High temperature and high pressure sintering: Same as Example 2, 4 GPa / 1200℃ / 20 min; (5) Discharge and post-processing: Same as in Example 1, final block size Φ12.6 mm×3.8 mm.
[0073] The high temperature and high pressure parameters are completely consistent with those in Example 2, except for the lack of "plasma etching + magnetron sputtering coating" pretreatment, forming a comparison of "same sintering parameters, with or without pretreatment", highlighting the independent role of pretreatment; without pretreatment, the interface between diamond and copper is only in physical contact, without chemical bonding and transition layer, which can intuitively reflect the impact of interface bonding on performance.
[0074] The performance test results and analysis are as follows: The relative density test result was 97.0%, a decrease of 1.6% compared to Example 2. Due to weak interfacial bonding and numerous interfacial gaps, the porosity increased to 3.0%. The room temperature thermal conductivity was 520 W / (m·K), a decrease of 20.0% compared to Example 2, failing to meet the requirement of ≥550 W / (m·K). The interfacial thermal resistance was as high as 1.8 × 10⁻⁶. -8 W -1 ·m 2 The thermal conductivity at 100℃ is 485 W / (m·K), a decrease of 20.5% compared to Example 2. Interfacial debonding intensifies at high temperatures, leading to a significant decrease in thermal conductivity. The coefficient of thermal expansion (25-500℃) is 7.0 × 10⁻⁶ W / (m·K). - 6 K -1 The expansion coefficient was increased by 34.6% compared to Example 2. The interfacial gaps led to poor thermal expansion consistency and increased expansion coefficient. The graphitization rate of diamond was 1.8%, which was 157.1% higher than that of Example 2. Without coating protection, diamond is prone to graphitization phase transformation under high temperature and high pressure. Microscopic morphology (SEM) observation showed that a large number of diamond particles were detached from the cross-section. The gap between the copper matrix and diamond was obvious, the pores were unevenly distributed, and the fracture mode was mainly "interfacial debonding". Without pretreatment, high pressure and high temperature could not effectively improve the problem of poor intrinsic wettability between diamond and copper. Example 8
[0075] No pretreatment + 6 GPa / 1400 ℃ / 15 min (no pretreatment + high temperature group with pressure limit): This example uses the high temperature parameters of the pressure limit of Example 4, 6 GPa / 1400 ℃ / 15 min, and cancels the pretreatment process. Compared with Example 4, it further verifies the performance gain of pretreatment under the optimal high pressure and high temperature conditions, and clarifies that the synergistic effect of "pretreatment + high temperature and high pressure" is irreplaceable.
[0076] In this embodiment, no pretreatment is required, and the rest is the same as in Embodiment 4. The specific process steps are as follows: (1) Powder mixing: Same as Comparative Example 1; (2) Powder pretreatment: Same as Comparative Example 1; (3) Pre-compression: Same as Comparative Example 1, the relative density of the billet is 66%; (4) High temperature and high pressure sintering: Same as Example 4, 6 GPa / 1400℃ / 15 min; (5) Discharge and post-processing: Same as in Example 1, final block size Φ12.6 mm×3.9 mm.
[0077] In this embodiment, the optimal high-temperature and high-pressure parameters of 6 GPa / 1400℃ are used to maximize the synergistic effect of high pressure and high temperature. Based on this, the pretreatment is eliminated, which can most intuitively reflect the limit gain of pretreatment. Without pretreatment, even under the highest pressure and high temperature, the interfacial wettability problem between diamond and copper cannot be solved, highlighting the core value of pretreatment for interfacial modification.
[0078] The performance test results and analysis are as follows: The relative density test result was 98.0%, a decrease of 1.5% compared to Example 4. High pressure and high temperature promoted copper filling, but interfacial gaps still existed, and the porosity increased to 2.0%. The room temperature thermal conductivity was 590 W / (m·K), a decrease of 18.1% compared to Example 4, meeting the requirement of ≥550 W / (m·K), but significantly lower than Example 4, with the interfacial thermal resistance being 3 times that of Example 4. The thermal conductivity at 100℃ was 555 W / (m·K), a decrease of 18.9% compared to Example 4, indicating poor interfacial stability at high temperatures, with a thermal conductivity decay rate of 6.0%. The coefficient of thermal expansion (25-500℃) was 5.6 × 10⁻⁶. -6 K -1 The coefficient of thermal expansion was 47.4% higher than that of Example 4, and the interfacial gaps resulted in poor thermal expansion synergy, with the expansion coefficient exceeding the ideal range. The graphitization rate of diamond was 1.0%, which was 400% higher than that of Example 4. Without coating protection, the risk of diamond graphitization under high temperature and high pressure was significantly increased. Microscopic morphology (SEM) observation showed that some diamond particles were detached from the cross-section, the interface between the copper matrix and diamond was clear, there was no obvious diffusion layer, a small amount of diamond skeleton was formed but discontinuous, high pressure promoted the bonding of diamond particles, but poor interfacial wettability prevented copper and diamond from effectively fusing, thus limiting performance.
[0079] In summary, the method for preparing a copper-based diamond composite heat dissipation material disclosed in this invention can produce high-performance copper-based diamond composite materials. Through optimized preparation processes, the resulting bulk material exhibits excellent comprehensive properties: relative density ≥98%, room temperature thermal conductivity ≥550 W / (m·K), and a thermal expansion coefficient that can be controlled within 2×10⁻⁶. -6 Up to 1×10 -5 K -1 Between these ranges, the thermal conductivity at 100℃ is ≥500 W / (m·K); the material with the best performance has a room temperature thermal conductivity of 720 W / (m·K) and a thermal conductivity at 100℃ of 685 W / (m·K), with a coefficient of thermal expansion (25-500℃) of 3.8 × 10⁻⁶. -6 K -1 This material not only has outstanding thermal conductivity and mechanical properties, but its coefficient of thermal expansion is also matched with that of semiconductor materials. It can effectively solve the thermal stress problem in the heat dissipation process of semiconductor devices, and ensure the stable operation of devices in high-temperature environments. It has important application value in the field of semiconductor heat dissipation.
[0080] The endpoints and any values of the ranges disclosed herein are not limited to the exact ranges or values, and these ranges or values should be understood to include values close to these ranges or values. For numerical ranges, the endpoint values of the various ranges, the endpoint values of the various ranges and individual point values, and individual point values can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.
[0081] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.
[0082] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.
Claims
1. A method for preparing a copper-based diamond composite heat dissipation material, characterized in that, The copper-diamond composite heat dissipation material comprises 50-95 vol% diamond and 5-50 vol% copper, with copper particle size of 2-50 μm. Its preparation method includes the following steps: (1) Roughening treatment of diamond Weigh diamond particles of single or multiple sizes and combine them, then etch them with plasma beam to obtain roughened diamond and expose more (100) crystal planes. (2) Diamond plating A copper protective layer is deposited on the roughened diamond surface obtained in step (1) using a magnetron sputtering device that integrates acoustic resonance components; (3) Powder mixing Weigh out copper powder, mix it with coated diamond powder using an acoustic resonance mixer, and place the mixed powder in a boron nitride crucible. (4) Powder pretreatment: The mixed powder in the boron nitride crucible was vacuum heat-treated using a tube furnace to remove organic matter and adsorbed gas from its surface, and the mixed powder was pre-pressed to form a green body. (5) Sintering: The green body obtained in step (4) is subjected to high temperature and high pressure sintering. The pressure is 2~6 GPa, the temperature is 800~1700 ℃, and the holding time is 10~60 min. The sintering sequence is as follows: first pressurize to the set pressure → then heat to the target temperature → hold at the temperature → cool down naturally → depressurize, and the temperature is measured in real time by the built-in thermocouple during the heating process; (6) Discharge After the high-temperature and high-pressure sintering equipment in step (5) is cooled and depressurized, the sintered copper-based diamond composite block is taken out to obtain the high-performance copper-based diamond composite material.
2. The preparation method of a copper-based diamond composite heat dissipation material according to claim 1, characterized in that: In step (4), during vacuum heat treatment, the vacuum level is higher than 10. -2 Pa, temperature 500-1000 ℃, holding time 10-30 min, heating rate 10 ℃ / min.
3. The preparation method of a copper-based diamond composite heat dissipation material according to claim 1, characterized in that: In step (4), during pre-pressing, a hydraulic press is used to apply pressure of 10-200 MPa, and the pressure holding time is 5-20 minutes.
4. The preparation method of a copper-based diamond composite heat dissipation material according to claim 1, characterized in that: In step (1), plasma beam etching uses argon ions or oxygen atoms to treat the surface of diamond. The power is 50~500 W, the treatment time is 5-30 min, the gas pressure is 10~100 Pa, and after the treatment is completed, the diamond particles are cleaned with deionized water.
5. The preparation method of a copper-based diamond composite heat dissipation material according to claim 1, characterized in that: In step (2), diamond and copper are placed in a mixing tank and mixed evenly by acoustic resonance. The resonance frequency is 40-60 Hz, the time is 5-60 min, the acceleration is 5-120 g, and the proportion of diamond during mixing is 50-95 vol% and the proportion of copper is 5-50 vol%.
6. The method for preparing a copper-based diamond composite heat dissipation material according to claim 1, characterized in that: In step (3), the copper powder has a purity of ≥99% and a particle size of 2~5 μm.
7. The preparation method of a copper-based diamond composite heat dissipation material according to claim 1, characterized in that: In step (1), the diamond raw material has a purity of ≥99%, a particle size of 20~700 μm, and a nitrogen content of <120 ppm.