High thermal conductivity diamond / metal joint and brazing method thereof

Abstract

The application provides a high-thermal-conductivity diamond / metal joint and a brazing method thereof, and relates to the technical field of brazing connection of dissimilar materials. The brazing method of the high-thermal-conductivity diamond / metal joint comprises the following steps: laser processing a diamond surface, and drawing a periodic micro-nano structure on the diamond surface; applying a brazing filler metal on the diamond surface with the periodic micro-nano structure, fixing in a sandwich structure of diamond / brazing filler metal / metal, and performing vacuum brazing to obtain the high-thermal-conductivity diamond / metal joint. In the laser processing process, the periodic micro-nano structure is introduced in the diamond ablation area, the interface heat transfer can be more efficient, the heat conduction performance is improved, the joint structure is uniform and defect-free, the mechanical properties of the joint are improved, and the problem that the traditional connection technology is difficult to simultaneously meet the mechanical property and heat transfer performance requirements of the diamond / metal interface is solved.

Description

Technical Field

[0001] The present invention relates to the technical field of brazing connection of dissimilar materials, in particular to a high thermal conductivity diamond / metal joint and a brazing method thereof. Background Art

[0002] Diamond, with its excellent properties, including low thermal expansion coefficient, high thermal conductivity, isotropic thermal conductivity, low dielectric constant and dielectric loss, and strong radiation resistance, is considered one of the most promising thermal management materials. To meet its structural and functional requirements, diamond is often bonded to metals or to itself. However, most metals cannot wet diamond or chemically react with it, hindering the metallurgical bonding between diamond and metal.

[0003] Currently, there are several main methods for achieving interfacial bonding between diamond and metal. First, direct bonding under high pressure and high temperature is used. However, traditional processing techniques make it difficult to achieve a good interface and suffer from poor mechanical properties. Second, an interfacial bonding layer is introduced by metallizing the diamond surface. However, current modification processes (such as electroless plating, chemical vapor deposition, and magnetron sputtering) all have the disadvantages of interface defects and weak interface strength, making it impossible to guarantee interface reliability and effective heat conduction. Next, there is the active brazing method. Adding carbide-forming elements such as Ti, Cr, Zr, and W to the brazing metal can achieve interfacial bonding of diamond. Various types of active brazing alloys, such as Ni-based, Cu-based, and Ag-Cu-based alloys, are used for diamond / metal bonding. However, due to the high processing temperature of most active brazing metals, severe thermal damage and microcracks will form inside the diamond, resulting in poor mechanical properties. Therefore, in some processing processes, melting point inhibitors such as Sn and In are added to the brazing metal system to effectively reduce the brazing temperature and form a low thermal conductivity interface phase. However, the formation of a low thermal conductivity interface phase will inevitably reduce the heat transfer performance of the diamond / metal joint. In summary, traditional connection technologies are difficult to simultaneously meet the mechanical and heat transfer performance requirements of the diamond / metal interface. Summary of the Invention

[0004] The problem solved by the present invention is how to solve the problem that traditional connection technology is difficult to simultaneously meet the mechanical property and heat transfer performance requirements of the diamond / metal interface.

[0005] To solve the above problems, the present invention provides a high thermal conductivity diamond / metal joint and a brazing method thereof.

[0006] In a first aspect, the present invention provides a method for brazing a high thermal conductivity diamond / metal joint, comprising the following steps:

[0007] Laser processing of diamond surface to draw periodic micro-nano structures on the diamond surface;

[0008] Brazing filler metal is coated on the surface of diamond with periodic micro-nano structures, fixed in a diamond / brazing filler metal sandwich structure, and vacuum brazing is performed to obtain a high thermal conductivity diamond / metal joint.

[0009] Optionally, before the step of laser processing the diamond surface, the method further includes the following steps: cleaning the base material, the base material including diamond and metal, soaking the base material in alcohol and ultrasonically cleaning it for 5-10 minutes, and then drying it after taking it out.

[0010] Optionally, the step of laser processing the diamond surface specifically includes: using a picosecond laser to laser process the diamond surface, wherein the laser spot diameter is 10-40 microns, the processing speed is 10-40 mm / s, the laser power is 0.5-12.5 W, and the repetition frequency is 100-400 KHz.

[0011] Optionally, the periodic micro-nano structure is a micrometer-scale periodic structure or a nanometer-scale periodic structure, and the periodic micro-nano structure includes a periodic micro-groove or hole array or a honeycomb array.

[0012] Optionally, when the solder is in powder form, the solder is mixed with cellulose and dissolved in terpineol to form a paste, which is then applied to the diamond surface with a periodic micro-nano structure, wherein the ratio of the solder, terpineol and cellulose is 2:1:1-3:1:1.

[0013] Optionally, the solder is an active solder, and the solder is silver-copper-indium-titanium or silver-copper-titanium or silver-copper-tin-titanium.

[0014] Optionally, the metal is aluminum or copper.

[0015] Optionally, the step of fixing the diamond / solder / metal sandwich structure specifically includes: placing the sandwich structure in a mold and applying a pressure of 0.5-4 MPa for fixing.

[0016] Optionally, vacuum brazing specifically includes placing the fixed sandwich structure into a vacuum brazing furnace for heating, and the vacuum brazing furnace maintains a vacuum degree of less than 10 -5 , maintain a heating rate of 10-20℃ / min, heat to 400℃ and keep warm for 5-20min, continue to maintain a heating rate of 10-20℃ / min, heat to 640℃-860℃, keep warm for 20-40min, and maintain a cooling rate of 5-10℃ / min to room temperature.

[0017] In a second aspect, the present invention provides a high thermal conductivity diamond / metal joint, which is manufactured using the brazing method for a high thermal conductivity diamond / metal joint as described in any one of the above items.

[0018] The beneficial effects of the high-thermal-conductivity diamond / metal joint and brazing method of the present invention are as follows: a diamond / metal interface structure is prepared on the diamond surface through laser processing, thereby increasing the effective contact area of ​​the diamond / metal interface, similar to introducing a heat sink structure at the interface, and achieving more efficient heat transfer at the interface. In addition, due to the introduction of periodic micro-nanostructures into the diamond ablation area during the scanning process, when phonons are reflected at the interface of dissimilar materials, the sidewalls of the micro-nanostructures provide an interface for the secondary transmission of phonons. The introduction of the periodic micro-nanostructures at the interface transforms the original two-dimensional heat transfer from the diamond to the metal interface into a three-dimensional heat transfer mode, improving the interface heat transfer capacity and thermal conductivity by approximately 20%. Furthermore, the brazing material is completely filled in the periodic micro-nanostructure, and the joint structure is uniform and defect-free. Regarding the improvement of the mechanical properties of the joint, the diamond / metal interface structure is prepared through laser processing. On the one hand, it improves the stress distribution of the joint and relieves the stress concentration of the joint. On the other hand, the periodic micro-nanostructure of the interface, through the crack deflection effect, prolongs the fracture path when the joint breaks in the face of external force, consumes the energy required for fracture, and improves the mechanical properties of the joint by about 30%. In addition, it does not require excessively high processing temperatures to avoid severe thermal damage and cracks in the diamond. Therefore, diamond / metal joints with uniform structure and no defects such as cracks can simultaneously possess better mechanical properties and thermal conductivity. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is a schematic diagram of the structure of the periodic micro-nano structure drawn on the diamond surface of Example 1;

[0020] Figure 2 This is a schematic diagram of the periodic micro-nano structure drawn on the diamond surface of Example 2;

[0021] Figure 3 This is a schematic diagram of the structure of the periodic micro-nano structure drawn on the diamond surface of Example 3;

[0022] Figure 4 Schematic diagram of the periodic micro-nanostructure drawn on the diamond surface in Examples 1, 2 and 3 under a microscope with a length unit of 50 μm;

[0023] Figure 5 Schematic diagram of the periodic micro-nanostructure drawn on the diamond surface in Example 1, Example 2 and Example 3 under a microscope with a length unit of 10 μm;

[0024] Figure 6 for Figure 5 Schematic diagram of the microscope in the middle area with a length unit of 1 μm. DETAILED DESCRIPTION

[0025] To make the above-mentioned objects, features, and advantages of the present invention more clearly understood, specific embodiments of the present invention are described in detail below with reference to the accompanying drawings. Although certain embodiments of the present invention are shown in the accompanying drawings, it should be understood that the present invention can be implemented in various forms and should not be construed as being limited to the embodiments described herein. Instead, these embodiments are provided to provide a more thorough and complete understanding of the present invention. It should be understood that the drawings and embodiments of the present invention are for illustrative purposes only and are not intended to limit the scope of protection of the present invention.

[0026] Unless otherwise defined, all technical and scientific terms used in this application have the same meanings as those commonly understood by those skilled in the art to which this application belongs. The terms used in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application.

[0027] The term "including" and its variations used in this document are open inclusions, that is, "including but not limited to"; the term "based on" means "at least partially based on"; the term "one embodiment" means "at least one embodiment"; the term "another embodiment" means "at least one other embodiment"; the term "some embodiments" means "at least some embodiments"; the term "optionally" means "optional embodiments". The relevant definitions of other terms will be given in the following description. It should be noted that the concepts of "first" and "second" mentioned in the present invention are used to distinguish different objects, rather than to describe a specific order or a primary and secondary relationship. In addition, the terms "first" and "second" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of this application, unless otherwise specified, "multiple" means two or more.

[0028] In related technologies, fabricating micro-nanostructure arrays at interfaces facilitates interfacial heat conduction. Researchers have found that interfacial micro-nanostructures can be an effective way to enhance interfacial heat conduction between solids. Furthermore, in the field of materials manufacturing, it is generally believed that such rough interfaces can also significantly improve the interfacial bonding strength of materials. Therefore, by introducing interfacial micro-nanostructures, it is expected that both the mechanical properties and thermal transfer performance of diamond / metal joints will be improved.

[0029] In response to the problems existing in the above-mentioned related technologies, this embodiment provides a high thermal conductivity diamond / metal joint and a brazing method thereof.

[0030] An embodiment of the present invention provides a brazing method for a high thermal conductivity diamond / metal joint, comprising the following steps:

[0031] Laser processing of diamond surface to draw periodic micro-nano structures on the diamond surface;

[0032] Brazing filler metal is coated on the surface of diamond with periodic micro-nano structures, fixed in a diamond / brazing filler metal sandwich structure, and vacuum brazing is performed to obtain a high thermal conductivity diamond / metal joint.

[0033] In this embodiment, laser processing is used to create a diamond / metal interface structure on the diamond surface, increasing the effective contact area of ​​the diamond / metal interface. This is similar to introducing a heat sink structure at the interface, enabling more efficient heat transfer at the interface. Furthermore, during the laser processing process, periodic micro-nanostructures are introduced into the diamond ablation region. When phonons are reflected at the interface of dissimilar materials, the sidewalls of the micro-nanostructures provide an interface for secondary transmission of phonons. The introduction of the periodic micro-nanostructures transforms the original two-dimensional heat transfer from the diamond to the metal interface into a three-dimensional heat transfer mode, improving the interface's heat transfer capacity and boosting thermal conductivity by approximately 20%, with a thermal conductivity greater than 500 W / (m·K). Furthermore, the brazing material is completely filled within the periodic micro-nanostructure, resulting in a uniform, defect-free joint structure.

[0034] Regarding the improvement of the mechanical properties of the joint, laser processing is used to create a diamond / metal interface structure. This not only improves the stress distribution in the joint and alleviates stress concentration, but also the periodic micro-nanostructure of the interface, through a crack deflection effect, prolongs the fracture path when the joint breaks in response to external forces, dissipating the energy required for fracture and improving the mechanical properties of the joint by approximately 30%, with a connection strength of ≥200 MPa. Furthermore, excessively high processing temperatures are not required, preventing severe thermal damage and cracks within the diamond.

[0035] Overall, diamond / metal joints with uniform structure and no defects such as cracks can have better mechanical properties and thermal conductivity.

[0036] Optionally, before the step of laser processing the diamond surface, the method further includes the following steps: cleaning the base material, the base material including diamond and metal, soaking the base material in alcohol and ultrasonically cleaning it for 5-10 minutes, and then drying it after taking it out.

[0037] In this optional embodiment, ultrasonic cleaning removes dirt, grease, corrosion products or other contaminants on the surface of the parent material.

[0038] Specifically, the base material is soaked in alcohol and placed in an ultrasonic cleaning machine for ultrasonic cleaning.

[0039] Optionally, the step of laser processing the diamond surface specifically includes: using a picosecond laser to laser process the diamond surface, wherein the laser spot diameter is 10-40 microns, the processing speed is 10-40 mm / s, the laser power is 0.5-12.5 W, and the repetition frequency is 100-400 KHz.

[0040] In this optional embodiment, the selection of various parameters in the laser processing step can obtain periodic micro-nano structures at the micron or nanometer level. From the perspective of thermal conductivity, the precision of the periodic micro-nano structures, processing defects and graphic parameters (such as specific surface area, aspect ratio, etc.) will all affect the interface thermal conductivity. The provided processing parameters can achieve the optimal thermal conductivity of the laser processing grooves.

[0041] Specifically, before laser processing, the eyepiece is focused to a laser spot diameter of 10-40 microns. The laser processing path is drawn using AutoCAD, with periodic micro-nanostructures such as periodic microgrooves, hole arrays, and honeycomb arrays individually drawn for different structures. After laser ablation, the surface is ultrasonically cleaned with alcohol for 5-10 minutes and then dried.

[0042] Optionally, the periodic micro-nano structure is a micrometer-scale periodic structure or a nanometer-scale periodic structure, and the periodic micro-nano structure includes a periodic micro-groove or hole array or a honeycomb array.

[0043] In this optional embodiment, periodic micro-nanostructures, such as periodic microgrooves, hole arrays, and honeycomb arrays, allow phonons to reflect at the interface of dissimilar materials through the sidewalls of the micro-nanostructures, providing a secondary transmission interface for the phonons. The introduction of these periodic micro-nanostructures transforms the original two-dimensional heat transfer from diamond to metal into a three-dimensional heat transfer mode, improving the interfacial heat transfer capacity. Through the crack deflection effect, these periodic micro-nanostructures extend the fracture path when the joint breaks in response to external forces, dissipating the energy required for fracture and improving the mechanical properties of the joint.

[0044] Optionally, when the solder is in powder form, the solder is mixed with cellulose and dissolved in terpineol to form a paste, which is then applied to the diamond surface with a periodic micro-nano structure, wherein the ratio of the solder, terpineol and cellulose is 2:1:1-3:1:1.

[0045] In this optional embodiment, laser processing prepares a diamond / metal interface structure on the diamond surface, and solder paste can be applied to the interface structure, increasing the contact area between the diamond / metal interface and the solder paste, and achieving more efficient heat transfer at the interface.

[0046] Specifically, the brazing material can be in the form of powder, foil, or adhesive tape. The foil or adhesive tape can be cut to the same size as the diamond and then applied to the diamond surface. The powdered brazing material is mixed with terpineol and cellulose to form a paste. The ratio of brazing material, terpineol, and cellulose is 2:1:1 to 3:1:1. The paste is evenly applied to the ablation side of the diamond surface using screen printing.

[0047] Optionally, the solder is an active solder, and the solder is silver-copper-indium-titanium or silver-copper-titanium or silver-copper-tin-titanium.

[0048] In this optional embodiment, active brazing material is used to achieve diamond / metal interface bonding.

[0049] Optionally, the metal is aluminum or copper.

[0050] In this optional embodiment, aluminum and copper are both metals with high thermal conductivity.

[0051] Optionally, the step of fixing the diamond / solder / metal sandwich structure specifically includes: placing the sandwich structure in a mold and applying a pressure of 0.5-4 MPa for fixing.

[0052] In this optional embodiment, after the pressure is applied, the diamond / solder paste / metal sandwich structure does not move relative to each other. The mold can be a graphite mold.

[0053] Optionally, vacuum brazing specifically includes placing the fixed sandwich structure into a vacuum brazing furnace for heating, and the vacuum brazing furnace maintains a vacuum degree of less than 10 -5 , maintain a heating rate of 10-20℃ / min, heat to 400℃ and keep warm for 5-20min, continue to maintain a heating rate of 10-20℃ / min, heat to 640℃-860℃, keep warm for 20-40min, and maintain a cooling rate of 5-10℃ / min to room temperature.

[0054] Specifically, the second heating temperature is 640-860°C, which is the melting point of the solder. The melting point of the silver-copper-indium-titanium solder is 640-720°C, the melting point of the silver-copper-tin-titanium solder is 720-800°C, and the melting point of the silver-copper-titanium solder is 720-860°C.

[0055] In this optional embodiment, the vacuum brazing temperature is relatively low, thereby preventing serious thermal damage and cracks inside the diamond due to high temperature.

[0056] An embodiment of the present invention provides a high thermal conductivity diamond / metal joint, which is manufactured using the brazing method for a high thermal conductivity diamond / metal joint as described in any one of the above items.

[0057] In this embodiment, the connection strength between diamond and metal of the obtained high thermal conductivity diamond / metal joint is ≥200 MPa, the joint thermal conductivity is >500 W / (m·K), and the high thermal conductivity diamond / metal joint has uniform structure and no obvious defects.

[0058] The present invention is further described below with reference to specific embodiments.

[0059] Example 1, brazing method of high thermal conductivity diamond / metal joint.

[0060] (1) Matrix treatment: Soak the diamond block and Cu block in alcohol, place them in an ultrasonic cleaner and clean them for 5 minutes, then take them out and dry them.

[0061] (2) Diamond surface laser ablation: The diamond surface is processed by a picosecond laser. The eyepiece is focused before processing, and the laser spot diameter is 10 microns. The laser processing path is drawn using AutoCAD, and periodic micro grooves are drawn separately according to different structures. The processing speed is set to 10 mm / s, the laser power is set to 0.5 W, and the repetition frequency is 100 KHz. After picosecond laser ablation, alcohol ultrasonic cleaning is used for 5 minutes and drying is carried out. Periodic micro-nano structures of micrometer or nanometer scale are drawn on the diamond surface, such as Figure 1 shown.

[0062] (3) Coating of active solder powder: Common commercial active solder silver copper indium titanium foil is cut into the same size as the diamond and coated on the ablation side of the diamond surface.

[0063] (4) Sample assembly: Diamond, solder, and Cu block are placed in a graphite mold according to a diamond / solder / Cu sandwich structure. The bottom of the graphite mold is fixed, and a pressure of 0.5 MPa is applied to the sandwich structure from the top.

[0064] (5) Brazing process: Place the welding structure together with the graphite mold into a vacuum brazing furnace and heat it. The vacuum degree is less than 10 -5 , the heating rate is maintained at 10℃ / min, the temperature is raised to 400 degrees Celsius and kept warm for 5 minutes, the heating rate is continued to maintain 10℃ / min, the temperature is raised to 640℃, kept warm for 20 minutes, the cooling rate is maintained at 5℃ / min, and after cooling to room temperature, a high thermal conductivity diamond / metal joint with good interface bonding can be obtained.

[0065] Example 2, brazing method of high thermal conductivity diamond / metal joint.

[0066] (1) Matrix treatment: Soak the diamond block and Cu block in alcohol, place them in an ultrasonic cleaner for 8 minutes, take them out and dry them.

[0067] (2) Diamond surface laser ablation: The diamond surface is processed by a picosecond laser. The eyepiece is focused before processing, and the laser spot diameter is 25 microns. The laser processing path is drawn using AutoCAD, and periodic micro grooves are drawn separately according to different structures. The processing speed is set to 25 mm / s, the laser power is set to 2.5 W, and the repetition frequency is 200 KHz. After picosecond laser ablation, alcohol ultrasonic cleaning is used for 8 minutes and drying is carried out. Periodic micro-nano structures of micrometer or nanometer scale are drawn on the diamond surface, such as Figure 2 shown.

[0068] (3) Coating of active solder powder: Common commercial active solder silver copper indium titanium foil is cut into the same size as the diamond and coated on the ablation side of the diamond surface.

[0069] (4) Sample assembly: Diamond, solder, and Cu block are placed in a graphite mold according to a diamond / solder / Cu sandwich structure. The bottom of the graphite mold is fixed, and a pressure of 2 MPa is applied to the sandwich structure from the top.

[0070] (5) Brazing process: Place the welding structure together with the graphite mold into a vacuum brazing furnace and heat it. The vacuum degree is less than 10 -5 , the heating rate is maintained at 15℃ / min, the temperature is raised to 400 degrees Celsius and kept warm for 10 minutes, the heating rate is continued to maintain 15℃ / min, the temperature is raised to 680℃, kept warm for 30 minutes, the cooling rate is maintained at 8℃ / min, and after cooling to room temperature, a high thermal conductivity diamond / metal joint with good interface bonding can be obtained.

[0071] Example 3, brazing method of high thermal conductivity diamond / metal joint.

[0072] (1) Matrix treatment: Soak the diamond block and Cu block in alcohol, place them in an ultrasonic cleaner for 8 minutes, take them out and dry them.

[0073] (2) Diamond surface laser ablation: The diamond surface is processed by a picosecond laser. The eyepiece is focused before processing, and the laser spot diameter is 40 microns. The laser processing path is drawn using AutoCAD, and periodic micro grooves are drawn separately according to different structures. The processing speed is set to 40 mm / s, the laser power is set to 12.5 W, and the repetition frequency is 400 KHz. After picosecond laser ablation, alcohol ultrasonic cleaning is used for 10 minutes and drying is carried out. Micron- or nanometer-scale periodic micro-nano structures are drawn on the diamond surface, such as Figure 3 shown.

[0074] (3) Coating of active solder powder: Common commercial active solder silver copper indium titanium foil is cut into the same size as the diamond and coated on the ablation side of the diamond surface.

[0075] (4) Sample assembly: Diamond, solder, and Cu block are placed in a graphite mold according to a diamond / solder / Cu sandwich structure. The bottom of the graphite mold is fixed, and a pressure of 4 MPa is applied to the sandwich structure from the top.

[0076] (5) Brazing process: Place the welding structure together with the graphite mold into a vacuum brazing furnace and heat it. The vacuum degree is less than 10 -5 , the heating rate is maintained at 20℃ / min, the temperature is raised to 400 degrees Celsius and kept warm for 20 minutes, the heating rate is continued to maintain 20℃ / min, the temperature is raised to 720℃, kept warm for 40 minutes, the cooling rate is maintained at 10℃ / min, and after cooling to room temperature, a high thermal conductivity diamond / metal joint with good interface bonding can be obtained.

[0077] Comparative Example 1, brazing method of diamond / metal joint.

[0078] (1) Matrix treatment: Soak the diamond block and Cu block in alcohol, place them in an ultrasonic cleaner and clean them for 5 minutes, then take them out and dry them.

[0079] (2) Coating of active solder powder: Common commercial active solder silver copper indium titanium foil is cut into the same size as the diamond and coated on the ablation side of the diamond surface.

[0080] (3) Sample assembly: Diamond, solder, and Cu block are placed in a graphite mold according to a diamond / solder / Cu sandwich structure. The bottom of the graphite mold is fixed, and a pressure of 0.5 MPa is applied to the sandwich structure from the top.

[0081] (4) Brazing process: Place the welding structure together with the graphite mold into a vacuum brazing furnace and heat it. The vacuum degree is less than 10 -5 , the heating rate is maintained at 10℃ / min, the temperature is raised to 400 degrees Celsius and kept warm for 5 minutes, the heating rate is continued to maintain 10℃ / min, the temperature is raised to 640℃, kept warm for 20 minutes, the cooling rate is maintained at 5℃ / min, and after cooling to room temperature, a high thermal conductivity diamond / metal joint with good interface bonding can be obtained.

[0082] Comparative Example 2, brazing method of diamond / metal joint.

[0083] (1) Matrix treatment: Soak the diamond block and Cu block in alcohol, place them in an ultrasonic cleaner for 8 minutes, take them out and dry them.

[0084] (2) Coating of active solder powder: Common commercial active solder silver copper indium titanium foil is cut into the same size as the diamond and coated on the ablation side of the diamond surface.

[0085] (3) Sample assembly: Diamond, solder, and Cu block are placed in a graphite mold according to a diamond / solder / Cu sandwich structure. The bottom of the graphite mold is fixed, and a pressure of 4 MPa is applied to the sandwich structure from the top.

[0086] (4) Brazing process: Place the welding structure together with the graphite mold into a vacuum brazing furnace and heat it. The vacuum degree is less than 10 -5 , the heating rate is maintained at 20℃ / min, the temperature is raised to 400 degrees Celsius and kept warm for 20 minutes, the heating rate is continued to maintain 20℃ / min, the temperature is raised to 720℃, kept warm for 40 minutes, the cooling rate is maintained at 10℃ / min, and after cooling to room temperature, a high thermal conductivity diamond / metal joint with good interface bonding can be obtained.

[0087] Effect embodiment

[0088] The periodic micro-nano structures drawn on the diamond surface in Examples 1, 2 and 3 were observed at microscope length units of 50 μm, 10 μm and 1 μm, respectively. When the microscope length unit was 50 μm, the periodic micro-nano structures in Example 1 were as follows: Figure 4 As shown in (a), the periodic micro-nanostructure of Example 2 is as follows Figure 4 As shown in (b), the periodic micro-nanostructure of Example 3 is as follows Figure 4 As shown in (c), when the microscope length unit is 10 μm, the periodic micro-nanostructure of Example 1 is as follows Figure 5 As shown in (a), Figure 5 The (d) area in (a) is enlarged to a length unit of 1 μm. Figure 6 As shown in (d), the periodic micro-nanostructure of Example 2 is as follows Figure 5 As shown in (b), Figure 5 The (e) area in (b) is enlarged to a length unit of 1 μm. Figure 6 As shown in (e), the periodic micro-nanostructure of Example 3 is as follows Figure 5 As shown in (c), Figure 5 The (f) area in (c) is enlarged to a length unit of 1 μm. Figure 6 As shown in (f).

[0089] Depend on Figures 1 to 6 It can be seen that the diamond / metal interface structure is prepared on the diamond surface by laser processing, which increases the effective contact area of ​​the diamond / metal interface, which is similar to introducing a heat sink structure at the interface.

[0090] The thermal diffusion coefficients of the joints obtained in Example 1 and Comparative Example 1 were tested, and the thermal diffusion coefficient of the joint in Example 1 was found to be 212.1 mm 2 / s, the thermal diffusion coefficient of the joint of Comparative Example 1 is 191.0 mm2 / s; the shear strength of the joints obtained in Example 3 and Comparative Example 2 was tested, and the shear strength of the joint in Example 1 reached 218±7 MPa, while the shear strength of the joint in Comparative Example 1 was 168±10 MPa. This shows that the introduction of periodic micro-nanostructures in the diamond ablation region during laser processing can result in a diamond / metal joint with superior mechanical properties and thermal conductivity.

[0091] Although the present invention is disclosed as above, the protection scope of the present invention is not limited thereto. Those skilled in the art may make various changes and modifications without departing from the spirit and scope of the present invention, and these changes and modifications will fall within the protection scope of the present invention.

Claims

1. A brazing method for high thermal conductivity diamond / metal joints, characterized in that: The following steps are involved: Laser processing a diamond surface to draw a periodic micro-nano structure on the diamond surface; the step of laser processing the diamond surface specifically comprises: using a picosecond laser to laser process the diamond surface, wherein the laser spot diameter is 10-40 microns, the processing speed is 10-40 mm / s, the laser power is 0.5-12.5 W, and the repetition frequency is 100-400 kHz; The diamond surface with the periodic micro-nano structure is coated with brazing material, fixed according to the sandwich structure of diamond / the brazing material / metal, and vacuum brazing is performed to obtain a high thermal conductivity diamond / metal joint; the vacuum brazing specifically includes placing the fixed sandwich structure into a vacuum brazing furnace for heating, and the vacuum brazing furnace maintains a vacuum degree of less than 10 -5 , maintain a heating rate of 10-20℃ / min, heat to 400℃ and keep warm for 5-20min, continue to maintain a heating rate of 10-20℃ / min, heat to 640℃-860℃, keep warm for 20-40min, and maintain a cooling rate of 5~10℃ / min to room temperature.

2. The brazing method of high thermal conductivity diamond / metal joint according to claim 1, characterized in that: Before the step of laser processing the diamond surface, the method further includes the following steps: cleaning the mother material, wherein the mother material includes diamond and metal, and the mother material is immersed in alcohol and ultrasonically cleaned for 5-10 minutes, and then taken out and dried.

3. The brazing method of high thermal conductivity diamond / metal joint according to claim 1, characterized in that: The periodic micro-nano structure is a micrometer-scale periodic structure or a nanometer-scale periodic structure, and the periodic micro-nano structure includes a periodic micro-groove or hole array or a honeycomb array.

4. The brazing method of high thermal conductivity diamond / metal joint according to claim 1, characterized in that: When the solder is in powder form, the solder is mixed with cellulose and dissolved in terpineol to form a paste, which is then applied to the diamond surface with the periodic micro-nano structure drawn thereon, wherein the ratio of solder, terpineol and cellulose is 2:1:1-3:1:

1.

5. The brazing method of high thermal conductivity diamond / metal joint according to claim 1, characterized in that: The solder is an active solder, and the solder is silver-copper-indium-titanium or silver-copper-titanium or silver-copper-tin-titanium.

6. The brazing method of high thermal conductivity diamond / metal joint according to claim 1, characterized in that: The metal is aluminum or copper.

7. The brazing method of high thermal conductivity diamond / metal joint according to claim 1, characterized in that: The step of fixing the diamond / solder / metal sandwich structure specifically includes: placing the sandwich structure in a mold and applying a pressure of 0.5-4 MPa to fix it.

8. A high thermal conductivity diamond / metal joint, characterized in that: The high thermal conductivity diamond / metal joint is made by the brazing method according to any one of claims 1 to 7.

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