Pretreatment method for preparing high-thermal-conductivity diamond / metal composite material

Abstract

The invention discloses a pretreatment method for preparing a high-thermal-conductivity diamond / metal composite material, which comprises the following steps of: performing surface activation on diamond particles, performing magnetron sputtering deposition on a transition layer and a metal layer, and performing an acoustic resonance mixing process on diamond and metal powder, so that the interface bonding of the high-thermal-conductivity diamond / metal composite material is excellent; due to the double-plating design of the carbide layer and the metal layer, the wettability is fundamentally improved, and the interface thermal resistance is reduced; the mixing uniformity is high, acoustic resonance mixing replaces traditional ball milling, coating damage is avoided, and the component consistency is improved; the process controllability is high, the film thickness can be accurately controlled through sputtering time, and flexible regulation and control of the diamond volume fraction are achieved; the preparation method is simple in process, high in compatibility and suitable for various follow-up forming processes such as SPS, HP and GPI, and a precursor is provided for a high-performance composite material.

Description

Technical Field

[0001] This invention belongs to the field of composite material preparation technology, and specifically relates to a pretreatment method for preparing high thermal conductivity diamond / metal composite materials. Background Technology

[0002] In recent years, the rapid development of information technology and the commercial application of 5G networks have propelled electronic devices towards high integration, multi-functionality, miniaturization, portability, and aesthetic appeal. This has led to a significant increase in the power density of electronic components within these devices, and a dramatic increase in the rate of heat generation per unit area. Achieving efficient heat dissipation and ensuring the lifespan and reliability of electronic components has become a critical issue urgently needing to be addressed in the field of electronic packaging technology. Using thermal management materials with high thermal conductivity is an important way to solve the heat dissipation problem of electronic components. However, traditional thermal management materials, due to inherent defects such as insufficient thermal conductivity and excessive coefficient of thermal expansion, cannot meet the increasingly stringent heat dissipation requirements of modern electronic devices. Therefore, the development of new thermal management materials that combine high thermal conductivity with a low coefficient of thermal expansion is urgently needed.

[0003] Diamond-metal composites are ideal for heat dissipation in electronic packaging due to their high thermal conductivity and low coefficient of thermal expansion. However, the poor wettability of diamond with metals and weak interfacial bonding result in high interfacial thermal resistance, limiting the performance of the composite material. Traditional processes, through single-layer coating or simple mixing pretreatment, struggle to achieve uniform interfacial bonding at high volume fractions, and the mixing process easily introduces impurities or causes component segregation, affecting subsequent densification effects.

[0004] 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 bonding film; assembling the pre-treated diamond and matrix sequentially from bottom to top in a mold according to a predetermined ratio; placing the mold in an equipment to prepare the diamond-copper composite material. This method improves the interfacial strength between copper and diamond by adding a bonding film between them, but does not improve the performance of the initial treatment.

[0005] Therefore, it is crucial to develop an efficient and uniform pretreatment process. Summary of the Invention

[0006] The purpose of this invention is to address the shortcomings of the prior art by providing a pretreatment method for preparing high thermal conductivity diamond / metal composite materials, thereby achieving uniformity and improving thermal conductivity of the composite materials.

[0007] To solve the above technical problems, the technical solution adopted by the present invention is as follows: A pretreatment method for preparing high thermal conductivity diamond / metal composite materials includes the following steps: (1) Surface activation of diamond particles Remove impurities and defects from the surface of the diamond, and select artificial or natural diamond particles with a particle size range of 10~000μm; (2) Acid washing activation The diamond particles were immersed in a mixture of concentrated nitric acid and sulfuric acid, ultrasonically treated, washed with deionized water, and dried. (3) Hydrogen etching The diamond was placed in an MPCVD apparatus, and the hydrogen flow rate was controlled at 100~300 sccm, the microwave power at 3000~4500W, the chamber pressure at 100~150 tor, the temperature at 800~950℃, and the etching time was 0.5~1h. After etching, the temperature is reduced at a rate of less than 5°C / min. (4) Magnetron sputtering coating composite layer A strong carbide transition layer and a metal layer are sequentially deposited on the surface of the diamond. First layer: Strong carbide transition layer. The activated diamond particles are loaded into a magnetron sputtering device, and a target material is selected. Sputtering parameters: vacuum degree ≤0.1Pa, argon atmosphere, power 100W, time control film thickness 50~200 nm; Second layer: Metal layer, By replacing the metal target in the same equipment, a metal layer is deposited using chemical-assisted magnetron sputtering. Parameters: Vacuum degree ≤0.1 Pa, power 200 W, time-controlled film thickness 500~2000 nm; After coating, a uniform composite coating is formed on the surface of the diamond particles; (5) Acoustic resonance mixing The coated diamond particles and pure metal powder are loaded into an acoustic resonant mixer at a predetermined volume ratio. Mixing parameters: frequency 50~200Hz, acceleration 30~100g, time 30~60 minutes, and inert gas protection.

[0008] In step (1), the diamond particles adopt a dual-size system, and a mixture of large particles of 300~1000μm and small particles of 10~250μm is used.

[0009] In step (4), the target material is selected from any one of molybdenum, zirconium, tungsten, titanium, and chromium.

[0010] In step (2), the mixture of concentrated nitric acid and sulfuric acid is mixed at a volume ratio of 3:1.

[0011] In step (2), the ultrasonic treatment is performed at 80°C for 30 to 60 minutes.

[0012] The beneficial effects of this invention are: This invention discloses a pretreatment method for preparing high thermal conductivity diamond / metal composite materials. Through surface activation of diamond particles, magnetron sputtering deposition of a transition layer and a metal layer, and an acoustic resonance mixing process of diamond and metal powders, the method achieves excellent interfacial bonding in the high thermal conductivity diamond / metal composite material. Furthermore, the dual-layer design of the carbide and copper layers fundamentally improves wettability and reduces interfacial thermal resistance. The method also ensures high mixing uniformity, with acoustic resonance mixing replacing traditional ball milling to avoid coating damage and improve compositional consistency. The process offers strong controllability, allowing for precise control of film thickness via sputtering time and flexible adjustment of the diamond volume fraction. Finally, the method demonstrates strong compatibility, suitable for various subsequent molding processes such as SPS, HP, and GPI, providing precursors for high-performance composite materials. Attached Figure Description

[0013] Figure 1 This is a process flow diagram of the present invention; Figure 2 This is a schematic diagram of the sample after pretreatment; Figure 3 These are the diamond samples and their electron scanning microstructure images from Examples 1 and 2; Figure 4 These are the sample and electron scanning microstructure images after sputtering in Example 2; Figure 5 This is a morphology diagram of the sample after sputtering in Example 1;

[0014] Figure 6 This is a morphology diagram of the sample after sputtering in Example 2. Detailed Implementation

[0015] 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.

[0016] This invention provides a pretreatment method for the preparation of high thermal conductivity diamond / metal composite materials, such as... Figures 1 to 6 As shown, it includes the following steps: (1) Surface activation of diamond particles: remove impurities and defects on the surface of diamond, increase surface energy, and enhance the adhesion of the coating; Select artificial or natural diamond particles, preferably with a particle size range of 10~1000μm. Preferably, they can be classified into a dual particle size system according to requirements, such as large particles of 300~1000μm and small particles of 10~250μm.

[0017] (2) Acid washing activation Diamond particles were immersed in a mixture of concentrated nitric acid and sulfuric acid in a volume ratio of 3:1, ultrasonically treated at 80°C for 30 minutes, and then washed with deionized water and dried.

[0018] (3) Perform hydrogen etching The diamond is placed in an MPCVD apparatus, and the hydrogen flow rate is controlled at 100~300 sccm, the microwave power at 3000~4500W, the chamber pressure at 100~150 tor, and the temperature is controlled at 800~950℃. The etching time is 0.5~1h. After the etching is completed, the temperature is reduced at a rate of less than 5℃ / min.

[0019] (4) Magnetron sputtering coating composite layer A strong carbide transition layer and a metal layer are sequentially deposited on the diamond surface to solve the interfacial wettability problem. First layer: Strong carbide transition layer, in which activated diamond particles are loaded into a magnetron sputtering device. The target material is selected from one of molybdenum, zirconium, tungsten, titanium, and chromium, with zirconium or titanium being preferred. Sputtering parameters: vacuum degree ≤0.1 Pa, argon atmosphere, power 100 W, time-controlled film thickness 50–200 nm.

[0020] This layer reacts with the diamond surface to form carbides, such as ZrC and TiC, providing a high-strength interfacial bond.

[0021] The second layer is a metal layer. The metal target (e.g., Cu, Al, etc.) is replaced in the same equipment, and the metal layer is deposited by chemical-assisted magnetron sputtering. The parameters are: vacuum degree ≤0.1 Pa, power 200 W, and time-controlled film thickness of 500~2000 nm. This metal layer provides good compatibility with the metal substrate, and metal-metal sintering can be achieved in subsequent processing to reduce interface defects.

[0022] After coating, a uniform composite coating is formed on the surface of the diamond particles, with a complete structure and no pores.

[0023] (5) Acoustic resonance mixing achieves high uniformity and pollution-free mixing of coated diamond particles and metal powder.

[0024] The coated diamond particles and metal powder are loaded into an acoustic resonant mixer at a predetermined volume ratio, with diamond accounting for 45-75%. The mixing parameters are: frequency 50-200Hz, acceleration 30-100g, time 30-60 minutes, and the atmosphere is protected by an inert gas such as argon.

[0025] This method avoids coating wear or impurity introduction caused by mechanical ball milling, ensuring uniform particle distribution. The mixed product is a loose and uniform composite powder that can be directly used in subsequent sintering processes, such as spark plasma sintering and melt infiltration.

[0026] The following detailed description is provided in conjunction with specific embodiments: Example 1

[0027] (1) Select diamond particles with a particle size of 200~300um and pure copper powder with a particle size of 2~5um.

[0028] (2) Immerse the diamond particles in a mixture of concentrated nitric acid and sulfuric acid (volume ratio 3:1), sonicate at 80°C for 30 minutes, then wash with deionized water and dry; diamond sample and electron scanning microstructure, as shown. Figure 3 As shown.

[0029] Hydrogen etching is performed by placing the diamond in an MPCVD apparatus, controlling the hydrogen flow rate at 100~300 sccm, the microwave power at 3000~4500W, the chamber pressure at 100~150 tor, and the temperature at 800~950℃ for etching for 0.5~1h; after etching, the temperature is reduced at a rate of less than 5℃ / min.

[0030] (3) The activated diamond particles are loaded into a magnetron sputtering device. The target material is a chromium target (purity ≥ 99.99%). Sputtering parameters: vacuum degree ≤ 10 -2 Pa, power 100 W, argon atmosphere, time-controlled film thickness 100 nm; sample and electron scanning microstructure after sputtering are as follows. Figure 4 As shown.

[0031] (4) Replace the copper target (purity ≥ 99.99%) in the same magnetron sputtering equipment and use chemical-assisted magnetron sputtering to deposit the copper layer; Parameter: Vacuum degree ≤ 10 -2 Pa, power 200 W, time controlled, film thickness 500 nm. Sample morphology after sputtering is as follows. Figure 5 As shown.

[0032] (5) According to the predetermined volume ratio, diamond accounts for 55%, and it is loaded into the acoustic resonance mixer; the mixing parameters are: frequency 80Hz, acceleration 50g, time 60min, and atmosphere is argon.

[0033] (6) The mixed sample was subjected to discharge plasma sintering; the parameters were: temperature 1000℃, pressure 50MPa, and holding time 1h.

[0034] The performance tests of the product obtained after sintering are as follows: Density (%): 96%, Coefficient of thermal expansion (10) -6 K -1 : 5.8; Thermal conductivity (W / m) -1 K -1 ): 582. Comparative Example 1

[0035] In Comparative Example 1, the sample was not pretreated. Diamond and copper powder were mixed in a certain proportion and then directly subjected to spark plasma sintering. The remaining processes were the same as in Example 1. The performance of the sintered sample was tested as follows: Density (%): 85%, Coefficient of thermal expansion (10) -6 K -1 ): 12.7; Thermal conductivity (W / m) -1 K -1 ): 280.

[0036] Compared with Comparative Example 1, the product prepared according to the method described in Example 1 has a density increased to 96% and a coefficient of thermal expansion decreased to 5.8 × 10⁻⁶. -6 K -1 Thermal conductivity is 582 W / m -1 K -1 .

[0037] The above comparison shows that spark plasma sintering is not the optimal sintering process, and that material pretreatment processes have a significant impact on product performance. Example 2

[0038] (1) Select diamond with a particle size of 200~300um and pure aluminum powder with a particle size of 2~5um.

[0039] (2) The diamond particles were immersed in a mixture of concentrated nitric acid and sulfuric acid at a volume ratio of 3:1, and ultrasonically treated at 80°C for 30 minutes. They were then washed with deionized water and dried. The diamond sample and its electron scanning microstructure are shown below. Figure 3 As shown. Hydrogen etching is performed: the diamond is placed in the MPCVD apparatus, the hydrogen flow rate is controlled at 100~300 sccm, the microwave power is 3000~4500W, the cavity pressure is 100~150 tor, the temperature is controlled at 800~950℃, and the etching time is 0.5~1h; after the etching is completed, the temperature is reduced at a rate of less than 5℃ / min.

[0040] (3) The activated diamond particles are loaded into a magnetron sputtering apparatus. The target material is a chromium target (purity ≥ 99.99%). Sputtering parameters: vacuum degree ≤ 10 -2 Pa, power 100 W, argon atmosphere, time-controlled film thickness 100 nm; sample and electron scanning microstructure after sputtering are as follows. Figure 4 As shown.

[0041] (4) Replace the aluminum target (purity ≥ 99.99%) in the same magnetron sputtering equipment and use chemical-assisted magnetron sputtering to deposit the aluminum layer. Parameter: Vacuum degree ≤ 10 -2 Pa Pa, power 200 W, time-controlled film thickness 500 nm; sample morphology after sputtering is as follows Figure 6 As shown.

[0042] (5) The mixture, with diamond comprising 65% of the volume, is loaded into an acoustic resonant mixer. Mixing parameters: frequency 80Hz, acceleration 70g, time 40min, atmosphere is argon.

[0043] (6) The mixed sample was subjected to discharge plasma sintering; the parameters were: temperature 750℃, pressure 50MPa, and holding time 1h.

[0044] The performance tests of the product obtained after sintering are as follows: Density (%): 97%, Coefficient of thermal expansion (10) -6 K -1 ): 8.2; Thermal conductivity (W / m) -1 K -1 ): 650. Comparative Example 2

[0045] In Comparative Example 2, the sample was not pretreated. Diamond and aluminum powder were mixed in a certain proportion and then directly subjected to spark plasma sintering. The remaining processes were the same as in Example 2. The performance of the sintered sample was tested as follows: Density (%): 88%, Coefficient of thermal expansion (10) -6 K -1 ): 16.3; Thermal conductivity (W / m) -1 K -1 ): 230.

[0046] Compared with Comparative Example 2, the product prepared according to the method described in Example 2 has a density increased to 97% and a coefficient of thermal expansion decreased to 8.2*10. -6 K -1 Thermal conductivity is 650 W / m -1 K -1 .

[0047] The above comparison shows that spark plasma sintering is not the optimal sintering process, and that material pretreatment processes have a significant impact on product performance. Example 3

[0048] (1) Two types of diamond particles with different particle sizes were selected, with particle sizes of 20~50um and 200~300um respectively, and pure copper powder with a particle size of 2~5um.

[0049] (2) Immerse the diamond particles in a mixture of concentrated nitric acid and sulfuric acid with a volume ratio of 3:1, sonicate at 80°C for 30 minutes, then wash with deionized water and dry. Perform hydrogen etching: Place the diamond in an MPCVD device, control the hydrogen flow rate to 100~300 sccm, microwave power to 3000~4500W, cavity pressure to 100~150 tor, and temperature to 800~950°C for etching for 0.5~1h; after etching, cool down at a rate of less than 5°C / min.

[0050] (3) The activated diamond particles are loaded into a magnetron sputtering device. The target material is a chromium target (purity ≥ 99.99%). Sputtering parameters: vacuum degree ≤ 10 -2 Pa, power 100 W, atmosphere is argon, time control film thickness is 100 nm.

[0051] (4) Replace the copper target (purity ≥ 99.99%) in the same magnetron sputtering equipment and use chemical-assisted magnetron sputtering to deposit the copper layer; Parameter: Vacuum degree ≤ 10 -2 Pa, power 200 W, time-controlled film thickness 500 nm.

[0052] (5) According to the predetermined volume ratio, diamond accounts for 55%, and it is loaded into the acoustic resonance mixer. Mixing parameters: frequency 80Hz, acceleration 50g, time 60min, atmosphere is argon.

[0053] (6) The mixed sample is subjected to discharge plasma sintering; parameters: temperature 1000℃, pressure 50MPa, holding time 1h.

[0054] The performance tests of the product obtained after sintering are as follows: Density (%): 98%, Coefficient of thermal expansion (10) -6 K -1 : 5.2; Thermal conductivity (W / m) -1 K -1 ): 703.

[0055] The performance test results, compared with Comparative Example 1 and Example 1, are shown in Table 1 below: Table 1 Performance Test Comparison

[0056] In Comparative Example 1, the sample was not pretreated; diamond and copper powder were mixed in a certain proportion and then directly subjected to spark plasma sintering.

[0057] Compared to Example 1, Example 3, performed according to the described method, achieved a density increase of 98% and a coefficient of thermal expansion decrease of 5.2*10. -6 K -1 Thermal conductivity is 703 W / m-1 K -1 .

[0058] In summary, the pretreatment process of materials has a crucial impact on the material properties, and spark plasma sintering is not the optimal sintering process.

[0059] If this patent uses terms such as "first" and "second" to define components, those skilled in the art should know that the use of "first" and "second" is merely for the convenience of describing the invention and simplifying the description, and the above terms have no special meaning.

[0060] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claims. The scope of protection of this invention is defined by the appended claims and their equivalents.

[0061] In the description of this invention, it should be understood that the terms "front", "rear", "left", "right", "center", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only used to facilitate the description of this invention and to simplify the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting the scope of protection of this invention.

Claims

1. A pretreatment method for preparing high thermal conductivity diamond / metal composite materials, characterized in that, Includes the following steps: (1) Surface activation of diamond particles Remove impurities and defects from the surface of the diamond, and select artificial or natural diamond particles with a particle size range of 10~000μm; (2) Acid washing activation The diamond particles were immersed in a mixture of concentrated nitric acid and sulfuric acid, ultrasonically treated, washed with deionized water, and dried. (3) Hydrogen etching The diamond was placed in an MPCVD apparatus, and the hydrogen flow rate was controlled at 100~300 sccm, the microwave power at 3000~4500W, the chamber pressure at 100~150 tor, the temperature at 800~950℃, and the etching time was 0.5~1h. After etching, the temperature is reduced at a rate of less than 5°C / min. (4) Magnetron sputtering coating composite layer A strong carbide transition layer and a metal layer are sequentially deposited on the surface of the diamond. First layer: Strong carbide transition layer. The activated diamond particles are loaded into a magnetron sputtering device, and a target material is selected. Sputtering parameters: vacuum degree ≤0.1Pa, argon atmosphere, power 100W, time control film thickness 50~200 nm; Second layer: Metal layer, By replacing the metal target in the same equipment, a metal layer is deposited using chemical-assisted magnetron sputtering. Parameters: Vacuum degree ≤0.1 Pa, power 200 W, time-controlled film thickness 500~2000 nm; After coating, a uniform composite coating is formed on the surface of the diamond particles; (5) Acoustic resonance mixing The coated diamond particles and pure metal powder are loaded into an acoustic resonant mixer at a predetermined volume ratio. Mixing parameters: frequency 50~200Hz, acceleration 30~100g, time 30~60 minutes, and inert gas protection.

2. The pretreatment method for preparing high thermal conductivity diamond / metal composite materials according to claim 1, characterized in that: In step (1), the diamond particles adopt a dual-size system, and a mixture of large particles of 300~1000μm and small particles of 10~250μm is used.

3. The pretreatment method for preparing high thermal conductivity diamond / metal composite materials according to claim 1, characterized in that: In step (4), the target material is selected from any one of molybdenum, zirconium, tungsten, titanium, and chromium.

4. The pretreatment method for preparing high thermal conductivity diamond / metal composite materials according to claim 1, characterized in that: In step (2), the mixture of concentrated nitric acid and sulfuric acid is mixed at a volume ratio of 3:

1.

5. The pretreatment method for preparing high thermal conductivity diamond / metal composite materials according to claim 1, characterized in that: In step (2), the ultrasonic treatment is performed at 80°C for 30 to 60 minutes.

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