Diamond-metal composite material having six sides coated with metal, and processing method therefor and use thereof

Abstract

Disclosed in the present application are a diamond-metal composite material having six sides coated with a metal, and a processing method therefor and the use thereof. The diamond-metal composite material having six sides coated with a metal is a composite material formed by sintering a hexahedral metal shell and at least one diamond-metal composite layer, which is arranged in the metal shell. The diamond-metal composite layer comprises a metal mesh and diamond particles having a surface coated with a coating, wherein the diamond particles are arranged in grids of the metal mesh, and gaps between the grids and the diamond particles are filled with a metal powder. Metal atoms in the metal mesh penetrate through the coating to diffuse towards the surfaces of the diamond, so as to as to form a mixed transition area. By adjusting the structural composition of the diamond-metal composite material and coating the surface of the diamond-metal composite material with a metal to form the diamond-metal composite material having six sides coated with a metal, the diamond in the composite material is prevented from being exposed, and the problems of difficult machining and difficult plating of the surface of the diamond are solved.

Description

A six-sided diamond-metal composite material with metal coating, its processing method and application Technical fields:

[0001] This invention relates to the field of metal composite material processing technology, specifically to a diamond-metal composite material with six-sided metal coating, its processing method, and its application. Background technology:

[0002] With the continuous miniaturization, integration, and high performance of modern electronic devices (including computing, 5G / 6G, batteries, and power electronic devices), power density is constantly increasing, leading to a sharp rise in device heat generation, resulting in performance degradation and device failure. Efficient heat dissipation is becoming a critical issue in electronic products. To alleviate this problem, integrating advanced thermal management materials into electronic devices can significantly improve their heat dissipation capabilities.

[0003] Traditional Invar and Kovar alloys have low thermal conductivity; tungsten-copper and molybdenum-copper alloys, while having low coefficients of thermal expansion, suffer from low thermal conductivity and high density. Metal matrix composites, however, combine the excellent thermal conductivity of metals with the low coefficient of thermal expansion of the reinforcement, and offer adjustable material properties, making them a commonly used thermal management material. Diamond has the highest thermal conductivity of any naturally occurring material (1200–2000 W·m⁻¹·K⁻¹) and a low coefficient of thermal expansion (1 x 10⁻⁶ K⁻¹), making it an ideal reinforcing phase. Furthermore, the artificial synthesis technology for diamond is quite mature, and its manufacturing cost is relatively low compared to other high thermal conductivity carbon materials. Aluminum, copper, and silver possess good electrical and thermal conductivity and relatively low density, making them commonly used matrix materials. Among these, Cu has a slightly lower thermal conductivity than Ag but better than Al, and its coefficient of thermal expansion is the lowest of the three, with a moderate price. Therefore, diamond / copper composites are gradually becoming the most widely researched and fruitful high thermal conductivity metal matrix composite material internationally.

[0004] Diamond's high hardness and its lack of reaction and poor wettability with copper make it difficult to guarantee the molding quality of diamond / copper composites. Therefore, the manufacturing process becomes a crucial factor affecting the performance of diamond / copper composites. Currently, most diamond / copper composite manufacturing processes rely on temperature and pressure to shape the composite material. Among the more widely used industrial methods are hot-pressing sintering, melt infiltration, and spark plasma sintering. Hot-pressing sintering is a common powder metallurgy process. When preparing diamond / copper composites using this method, a mixture of diamond and copper powder is placed in a mold and simultaneously heated and pressurized in a vacuum hot press furnace. While hot-pressing sintering is simple to operate and doesn't require highly sophisticated equipment, the bonding between the diamond and copper phases is weak, resulting in low thermal conductivity, which is difficult to meet the current demands for high-power devices. Melt infiltration can be divided into pressureless melt infiltration (PLI) and pressure melt infiltration (PI). Utilizing the principle that the melting point of the metal matrix is ​​lower than that of the reinforcing particles, under pressure or capillary action, molten copper infiltrates into the gaps between diamond particles to obtain a bulk composite material. Pressureless infiltration is a simple and convenient process, relatively easy to implement, and the shape of the resulting composite material is easily controllable. However, pressureless infiltration has extremely high requirements for the interfacial wettability between diamond and copper; the transition layer between diamond and copper must be uniform and complete. Furthermore, pressureless infiltration does not apply external pressure, relying solely on the capillary force of the preform to drive the copper melt infiltration, resulting in a long infiltration time and less than ideal results. Pressure infiltration, on the other hand, introduces external force during the infiltration process, which can promote copper infiltration. Diamond composite materials prepared by pressure infiltration require less time, are more efficient, have higher density, and are more widely applicable. However, pressure infiltration is a relatively complex process. The preparation of the reinforcing preform, the melting of the matrix, the gas flow during infiltration, and the solidification of the matrix all significantly affect the sample's properties. This method places high demands on the design of the graphite mold, the control of sintering parameters, and the selection of sintering equipment. Spark plasma sintering (SPS) is a novel material preparation method developed in recent years. It enables rapid densification of powder particles at temperatures below their melting point. The main process involves introducing a pulsed current and applying pressure to the powder particles. The plasma generated by the spark discharge uniformly heats the particles, activating their surface and achieving ultra-fast densification sintering. It offers advantages such as high sintering speed, rapid heating and cooling, low sintering temperature, direct sintering into dense bodies, and energy efficiency. However, the mechanism of SPS is not yet fully understood, and the entire sintering process of actual composite materials cannot be quantified. Therefore, precise control of the interphase composition and interfacial product size is difficult. Furthermore, the relatively low sintering temperature and pressure make it difficult to achieve diamond bonding. Consequently, the thermal conductivity of materials prepared using this method rarely exceeds 700 W / (m·K). Moreover, the relatively low temperature and pressure of SPS make it difficult to achieve a tight bond between diamond and copper, resulting in composite materials with low thermal conductivity.

[0005] Furthermore, existing technologies include other methods for preparing diamond-copper composites. For example, diamond-copper composites prepared by hot pressing, despite some particle size distribution, suffer from a low diamond volume fraction and high porosity due to the inability to control diamond distribution. This limits the adjustable range of thermal expansion coefficient and thermal conductivity, and results in poor surface finish and inability to achieve complete density. While pressure infiltration can produce relatively dense diamond-copper composites, the fluidity of the copper molten metal causes diamond particles to move during preparation, compromising the uniformity, consistency, and repeatability of the composite material.

[0006] Patent CN110453126B discloses a diamond / metal-based composite thermal conductive material and its preparation method. The steps are as follows: A metal foil is laid at the bottom of a mold; a metal mesh with a grid size matching that of the diamond powder in the first diamond layer is placed, and the diamond powder in the first diamond layer is filled; more metal foil is laid, and a metal mesh with a grid size matching that of the diamond powder in the second diamond layer is placed, and the diamond powder in the second diamond layer is filled; the above steps are repeated, stacking the materials to the desired layers to obtain a diamond / metal-based matrix composite; the diamond / metal-based matrix composite is then sintered using a vacuum hot-pressing method to prepare the diamond / metal composite thermal conductive material. This method uses a metal foil interlayer to fill the remaining gaps between diamond particles; however, selecting the appropriate metal foil thickness is difficult, requiring multiple experiments to obtain a suitable thickness, and the thickness needs to be readjusted as the diamond particle size changes; there is a risk of delamination between the diamond powder layers, resulting in high brittleness of the composite material.

[0007] Because of the large difference in electrode potential between diamond and other metals, it takes a long time to electroplate copper onto the surface of diamond / copper composite material, and the resulting copper coating has poor density and is uneven. Summary of the Invention:

[0008] To overcome the shortcomings of the prior art, the purpose of this application is to provide a diamond-metal composite material with six sides covered by metal. By adjusting the structural composition of the diamond-metal composite material and covering its surface with metal to form a diamond-metal composite material with six sides fully covered by metal, the diamond in the composite material is avoided from being exposed, the problem of difficult processing and gold plating of diamond surface is solved, thereby reducing the cost of heat sink products (such as diamond copper) and improving the surface properties and thermal conductivity of the composite material.

[0009] To solve the above problems, the technical solution adopted in this application is as follows:

[0010] This application provides a six-sided metal-coated diamond-metal composite material, which is a composite material formed by sintering a hexahedral metal shell and at least one diamond-metal composite layer placed in the metal shell; the diamond-metal composite layer includes a metal mesh and diamond particles with a coating on the surface, the diamond particles are arranged in the mesh of the metal mesh, and the gaps between the mesh and the diamond particles are filled with metal powder consistent with the metal mesh material; the metal atoms in the metal mesh diffuse through the coating to the diamond surface to form a mixing transition zone.

[0011] As a further preferred embodiment, the mesh described in this application is a regular hexahedral structure or a regular octahedral honeycomb structure, the mesh wall thickness is 10-20 μm, and the edge length L of the mesh is 10-20 μm larger than the particle size D of a single diamond particle.

[0012] As a further preferred embodiment, the diamond described in this application is one or more of the following: synthetic high-temperature high-pressure diamond, synthetic CVD diamond, or natural diamond, and the diamond particle size is 100-1000 μm.

[0013] As a further preferred embodiment, the mixed transition region described in this application is a ternary phase formed by metal-coating material-C, such as a ternary phase formed by Cu-coating material-C or an Al-coating material-C; the thickness of the ternary phase is 1-2 μm.

[0014] As a further preferred embodiment, the coating described in this application is a coating formed of one material selected from Ti, Cr, W, V, and Zr, or a composite coating formed of two or more materials; the thickness of the coating is 0.1 to 0.5 μm.

[0015] As a further preferred embodiment, the metal shell described in this application is an aluminum foil shell, and the materials of the metal mesh and metal powder are both aluminum; there is a 3-8 nm aluminum oxide nanolayer at the interface between the aluminum foil shell and the diamond.

[0016] As a further preferred embodiment, the metal shell described in this application is a copper foil shell, the metal mesh is a copper mesh, and the metal powder used to fill the gaps is pure copper powder or mixed copper powder with mixed active ingredients; the particle size of the copper powder is 0.5-5μm.

[0017] This application also provides a method for processing a diamond-metal composite material with six-sided metal coating, including the following steps:

[0018] Making a hexahedral metal box: Stamp and fold a metal sheet into a hexahedral metal box with a lid and an opening, and place it into a mold;

[0019] Select a metal mesh: Use a metal mesh with a uniform grid, the size of which is the same as the inner bottom surface size of the hexahedral metal box; lay the metal mesh inside the hexahedral metal box;

[0020] Diamond particle arrangement: Diamond particles with a surface coating are arranged in each grid of the metal mesh using a arranging machine;

[0021] Void filling: Place the hexahedral metal box and mold with diamond particles arranged on the vibration table, and spray metal powder onto the metal mesh in vibration mode until the metal powder fills the voids of the metal mesh and reaches the same height as the metal mesh.

[0022] Multi-layer stacking: After the gap filling step, place a metal mesh inside the hexahedral metal box, arrange diamond particles and continue the gap filling step until the metal mesh is level with the height of the hexahedral metal box. Cover the opening with the top cover and integrate the top cover with the metal box to obtain the preform.

[0023] Sintering: The above preforms are placed in a sintering furnace for sintering to obtain sintered composite materials.

[0024] As a further preferred embodiment, in the processing method described in this application, when making a hexahedral metal box, the unfolded hexahedral shape is first punched out, and creases are reserved at the edges; after folding along the edges, a hexahedral box is formed, and metal adhesive is used to connect the edges.

[0025] As a further preferred embodiment, in the processing method described in this application, when making a hexahedral metal box, laser cutting or wire cutting is used to form a hexahedral unfolded shape, and creases are pre-etched at the edges; after folding along the edges, local welding is performed at the edge joints to combine adjacent edges.

[0026] As a further preferred embodiment, in the processing method described in this application, the metal mesh has a hexahedral or octahedral honeycomb structure, and the edge length L of the mesh is 10-20 μm larger than the particle size D of a single diamond particle.

[0027] As a further preferred embodiment, in the processing method described in this application, the vibration table is a mechanical vibration table with a vibration frequency of 2-10Hz, a vibration time of 5-20min, and an amplitude of 0.1-0.5mm.

[0028] As a further preferred embodiment, in the processing method described in this application, when filling the gaps, an electric field is applied using electrostatic spraying technology to orient the metal powder into the grid gaps, and the electric field voltage is 5-10kV.

[0029] As a further preferred embodiment, the metal shell described in this application is a copper foil shell, the metal mesh is a copper mesh, and the metal powder used to fill the gaps is pure copper powder or mixed copper powder with mixed active ingredients; the particle size of the copper powder is 0.5-5μm.

[0030] As a further preferred embodiment, in the processing method described in this application, the active ingredient is one or more of nano-Al2O3, nano-SiC, nano-TiC, nano-Y2O3, and nano-graphene, and the amount of the active ingredient accounts for 0.1-1.0 wt% of the weight of the copper powder.

[0031] As a further preferred embodiment, in the processing method described in this application, the sintering and forming adopts vacuum hot pressing sintering, with a vacuum degree of <10Pa, a hot pressing pressure of 20-40MPa, a sintering temperature of 850-920℃, and a time of 55-65min.

[0032] As a further preferred embodiment, in the processing method described in this application, the sintering molding adopts segmented sintering, including,

[0033] Pre-sintering: Pulse current assisted sintering is adopted, with a sintering temperature of 820-850℃, a pressure of 20-30MPa, a time of 10-20min, and a superimposed pulse current of 100-1000A with a frequency of 1-10Hz;

[0034] Final sintering: Hot pressing sintering combined with hydrogen atmosphere control is adopted. The sintering temperature is 880-900℃, the pressure is 30-40MPa, and the sintering time is 30-60min. The oxygen content in the H2 atmosphere is ≤10ppm.

[0035] As a further preferred embodiment, the metal shell described in this application is an aluminum foil shell, the metal mesh is an aluminum mesh, and the metal powder used to fill the gaps is aluminum powder; the particle size of the aluminum powder is 0.5-5μm.

[0036] In the aluminum foil shell scheme, the sintering pre-sintering is performed by using pulse current-assisted sintering at a temperature of 520-550℃, a pressure of 30-40MPa, a time of 10-20min, and superimposed with a pulse current of 500-30000A.

[0037] Final sintering: Hot pressing sintering combined with hydrogen atmosphere control is adopted. The sintering temperature is 600-650℃, the pressure is 30-40MPa, and the sintering time is 30-60min. The oxygen content in the H2 atmosphere is ≤10ppm.

[0038] As a further preferred embodiment, the processing method described in this application also includes a step of surface polishing the sintered composite material.

[0039] The application of the six-sided metal-coated diamond-metal composite material described in this application in the fabrication of heat dissipation substrates for electronic devices.

[0040] This application also provides a heat dissipation substrate for electronic devices, comprising a composite material formed by sintering a hexahedral metal shell and at least one diamond-metal composite layer disposed within the metal shell; the diamond-metal composite layer comprises a metal mesh and diamond particles coated with a coating, the diamond particles being arranged in the mesh of the metal mesh, and the gaps between the mesh and the diamond particles being filled with metal powder; metal atoms in the metal mesh diffuse through the coating to the diamond surface, forming a mixed transition zone.

[0041] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0042] 1. The diamond-metal composite material with six-sided metal coating described in this application adopts a six-sided coating structure. After sintering, the metal box forms a dense outer layer, which improves the bending strength of the composite material and provides electromagnetic shielding and anti-oxidation protection. Furthermore, it is bonded to the inner layer as a whole through subsequent sintering. The six-sided coating design prevents the penetration of oxidizing and corrosive media.

[0043] 2. In the six-sided diamond-metal composite material described in this application embodiment, the diamond-metal composite layer includes a metal mesh and diamond particles with a coating on the surface. During sintering, the diamond forms a three-dimensional interpenetrating structure, and the metal mesh and metal powder fill and construct a continuous heat conduction path, which effectively improves the overall thermal conductivity of the composite material, making it suitable for heat dissipation substrates for high-power electronic devices.

[0044] 3. In the six-sided metal-coated diamond-metal composite material described in the embodiments of this application, the volume fraction of the metal mesh skeleton and diamond particles is adjustable. By adjusting the metal mesh aperture, the thermal expansion coefficient of the composite material is made to be nearly matched with that of electronic components such as semiconductor chips. The coating on the diamond surface enhances the interfacial bonding strength through chemical bonding, avoiding interfacial peeling during high-temperature service.

[0045] 4. In the processing method of the six-sided metal-coated diamond-metal composite material described in this application embodiment, metal atoms in the diamond-metal composite layer diffuse to the diamond surface through the coating to form a mixed transition zone, alleviating the problem of poor wettability between diamond and metal and reducing interfacial thermal resistance. Metal powder is filled into the gaps between the mesh and diamond particles. On the one hand, the metal powder and the metal mesh jointly support the diamond particles, avoiding local stress concentration that could lead to interfacial cracking; on the other hand, the metal powder fills local micron-level gaps, reducing interfacial thermal resistance and improving thermal conductivity. During sintering, the metal powder, due to its large specific surface area and high activity, preferentially melts and penetrates into the micropores of the diamond surface coating, promoting the diffusion of metal atoms to the diamond surface, forming a mixed transition zone, and enhancing interfacial bonding strength. This solves the performance bottleneck caused by interfacial discontinuity in traditional diamond / metal composite materials, providing a new direction for high-density electronic packaging.

[0046] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments. Attached Figure Description

[0047] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0048] Figure 1 is a photograph of the diamond-copper alloy material with six sides coated with copper as described in the embodiment of this application, after the surface is polished to reveal the diamond-copper layer.

[0049] Figure 2 is an X-ray image of the diamond monolayer arrangement of the six-sided metal-coated diamond-metal composite material described in the embodiment of this application.

[0050] Figure 3 is an X-ray image of the diamond-metal composite material with six-sided metal coating and diamond double-layer arrangement as described in the embodiment of this application.

[0051] Figure 4 is a schematic flowchart of the diamond-metal composite material processing method with six-sided metal coating as described in the embodiments of this application. Detailed implementation method:

[0052] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0053] The term "comprising" and other equivalent descriptive terms used in the specification and claims of this application are intended to cover a non-exclusive inclusion, which includes both the contents explicitly described in the specification and claims and steps or units that are not described in the specification and claims but are inherent in the product, method or structure.

[0054] This application provides a six-sided coated diamond-metal composite material, which is a composite material formed by sintering a hexahedral metal shell and at least one diamond-metal composite layer placed within the metal shell. The hexahedral metal shell creates a six-sided coated structure on the surface of the diamond-metal composite layer, forming a dense shell that blocks the permeation of oxygen and moisture. Since the metal-diamond interface has poor wettability, relies on high-cost coatings, and has high interfacial thermal resistance, the synergistic diffusion between the metal shell and the internal metal mesh during sintering can effectively reduce the interfacial thermal resistance. Traditional materials are prone to thermal stress cracking due to the large difference in the coefficients of thermal expansion (CTE) between metal and diamond. The diamond-metal composite layer described in this application includes a metal mesh and diamond particles coated with a layer of metal powder. The diamond particles are arranged within the mesh, and the gaps between the mesh and the diamond particles are filled with metal powder. This combination of a metal mesh framework and metal powder filling allows for adjustment of the CTE, making it nearly match the CTE of electronic components such as semiconductor chips. The metal shell and metal powder filling lower the sintering temperature, preventing diamond graphitization, reducing energy consumption, and improving yield. In this application, during sintering, metal atoms in the metal mesh diffuse through the coating to the diamond surface, forming a mixing transition zone. Traditional materials exhibit significant anisotropy in thermal conductivity, making it difficult to meet directional heat dissipation requirements. In this application, the metal shell and the internal metal mesh-metal powder form a three-dimensional interpenetrating structure, effectively improving the thermal conductivity and isotropy of the composite material.

[0055] Furthermore, in some embodiments of this application, the mesh is a regular hexahedral structure. The regular hexahedral mesh forms a homogeneous metal skeleton in the X / Y / Z directions. The regular arrangement of the metal mesh wire diameter and the mesh edge length can reduce the isotropic deviation of thermal conductivity. The 90° intersection structure of the regular hexahedral mesh forms four-way support when subjected to bending (such as in bending tests), which is beneficial to improving stress dispersion efficiency. The right-angled edges of the regular hexahedral mesh can also guide the molten metal powder to flow along the edge direction during sintering, which can preferentially coat the surface of diamond particles. In addition, the regular porosity of the regular hexahedral structure allows the metal powder to be fully densified at a lower temperature, avoiding local unmelted areas. When diamond particles are embedded into the mesh by a vibration arrangement machine, gaps need to be reserved to compensate for particle size tolerances and arrangement mechanical errors, and to avoid particles getting stuck or scratching the surface of the metal mesh. At the same time, the gaps can also provide flow channels for the metal powder. During vibration, the metal powder can penetrate into the micro-gap between the particles and the mesh wall, increasing the interface contact area and forming a three-phase cross-linked structure of "diamond-metal powder-metal mesh". Because the flow of molten metal is restricted and the interfacial bonding is incomplete, the reserved gaps allow the metal powder to fully encapsulate the diamond particles during sintering and melting. Metal atoms diffuse along the particle surface coating to form a transition layer, providing interfacial integrity. Furthermore, the thermal expansion mismatch between diamond and metal can generate stress at the interface; the gaps can absorb this stress through the plastic deformation of the metal powder, preventing stress concentration and microcracks. Additionally, the metal powder and metal mesh have different shrinkage rates during sintering; the gaps provide a deformation buffer space, stabilizing the shrinkage rate and preventing delamination or warping. Therefore, in the embodiments of this application, the space size of each mesh is slightly larger than the diameter of the placed diamond particles. Specifically, through precise calculations, when the edge length L of the mesh is 10–20 μm larger than the diameter D of a single diamond particle (L = D + 10–20 μm), it can effectively balance particle positioning accuracy, interfacial bonding strength, and process tolerance. In this application, the mesh wall thickness is 10–20 μm. In addition to the aforementioned hexahedral structure, in some embodiments, the mesh is an octahedral honeycomb structure. Under multi-directional loads, the stress distribution is uniform, and it exhibits higher compressive strength compared to the hexahedral structure. Under pressure, it absorbs energy through the buckling of the wall panels, resulting in higher energy absorption efficiency than the hexahedral structure. However, compared to the hexahedral structure, it is more difficult to manufacture and relatively more expensive. In the embodiments of this application, the metal shell, metal mesh, and metal powder are made of the same material, specifically copper or aluminum.

[0056] Based on the above scheme, the diamond used in the embodiments of this application is one or more of the following: synthetic high-temperature high-pressure diamond, synthetic CVD diamond, or natural diamond. The size of the diamond particles affects the thermal conductivity, mechanical properties, and ease of processing of the material. In terms of performance, larger diamond particles form more direct heat conduction paths in composite materials because larger particles are more likely to contact each other, thereby improving thermal conductivity; however, on the other hand, larger particles lead to more interfaces, resulting in poor bonding between diamond and copper, which increases interfacial thermal resistance and reduces overall thermal conductivity. Smaller particles can fill more densely, but require more interfacial treatment; otherwise, they are prone to forming pores, affecting thermal conductivity and mechanical strength. In terms of processing, larger particles are easier to disperse during mixing and molding, but require higher pressure to ensure bonding between particles; while smaller particles are prone to agglomeration. In terms of mechanical properties, larger particles can act as a reinforcing phase to improve the hardness of the composite material, but larger particles are prone to becoming crack initiation points, leading to reduced material toughness; smaller particles can be more uniformly distributed, improving the overall strength and toughness of the material. Therefore, in some embodiments of this application, considering thermal conductivity, mechanical properties, and ease of processing, the diamond particles used have a particle size of 100–1000 μm. Preferably, the diamond particle size is 200–500 μm.

[0057] Furthermore, in the embodiments of this application, the coating on the diamond surface is a coating formed from one of the materials selected from Ti, Cr, W, V, and Zr, or a composite coating formed from two or more materials, and the thickness of the coating is 0.1–0.5 μm. For example, in some embodiments, Ti is used as the target material, and a dense layer is formed on the diamond surface by magnetron sputtering, with a TiC phase generated at the interface, and the thickness is about 100 nm. In other embodiments, Ti and Cr targets are sputtered simultaneously to achieve an atomically hybrid coating to improve the interfacial shear strength. In still other embodiments, a composite layer of multiple materials can be used. For example, a Cr layer (0.2–0.3 μm) is first formed on the surface of the diamond particles by magnetron sputtering, and then a W layer (0.1–0.2 μm) is formed on the surface of the Cr layer. In some embodiments, a Ti-Zr-Cu gradient coating can be used, where the bottom layer is a 0.1-0.2 μm Ti layer that reacts with diamond at the interface to form TiC, enhancing the bonding; the middle layer is a 0.1-0.2 μm Zr layer, utilizing its high melting point to achieve a transition in the coefficient of thermal expansion; and the top layer is a 0.2-0.3 μm Cu layer to optimize the wettability of the diamond surface. Besides the above implementations, alternating Ti / V deposition can also be used, with each layer having a thickness of 20-50 nm, resulting in a total coating thickness of 0.5 μm.

[0058] In some embodiments, the metal shell is a copper foil shell, the metal mesh is a copper mesh, and the metal powder used to fill the gaps is all copper. In these embodiments, after sintering, the surface of the copper foil shell of the six-sided copper-coated diamond-coated composite material is a nanocrystalline copper layer with a grain size of 50-100 nm. Nanocrystalline copper has high hardness; its surface wear resistance is improved, avoiding scratches and deformation during processing and service; and the nanocrystalline surface has low roughness, which can reduce interfacial thermal resistance when used as a heat sink material. The copper inside the six-sided copper-coated diamond-coated composite material is a coarse-grained copper matrix with a grain size of 5-10 μm. Coarse-grained copper has high thermal conductivity and higher elongation at break than nanocrystalline copper, which can avoid brittle cracking. Figure 1 is a physical image of the diamond-copper layer exposed after polishing the surface of the six-sided copper-coated diamond-copper composite material described in the embodiments of this application. It can be seen from the figure that the diamond particles are neatly and uniformly arranged.

[0059] In other embodiments, the metal shell is an aluminum foil shell, and both the metal mesh and the metal powder are made of aluminum. Diamond serves as the main heat conduction channel, forming a three-dimensional interpenetrating network with the aluminum matrix, which effectively improves the overall thermal conductivity of the composite material. The interface between the aluminum foil shell and the diamond contains a 3-8 nm alumina nanolayer. This 3-8 nm alumina can suppress the excessive formation of harmful Al4C3 phases and reduce phonon scattering through an atomically smooth interface.

[0060] Furthermore, in the embodiments of this application, the surface of the six-sided coated diamond-metal composite material after sintering single-layer copper mesh diamond particles and double-layer copper mesh diamond particles was completely polished, and the internal structure was observed using X-rays. Figure 2 shows an X-ray image of a single-layer diamond particle arrangement. Figure 3 shows an X-ray image of a double-layer diamond particle arrangement; as can be seen from the figures, the double-layer structure forms a denser heat-conducting network through the cross-arrangement of diamond particles, further reducing the interfacial thermal resistance. Tests revealed that the multi-layer diamond arrangement can not only achieve directional heat dissipation for local hot spots through the distribution of diamonds of different particle sizes or densities, avoiding performance degradation caused by concentrated heat flow in a single-layer structure; it can also achieve layered adaptation of the overall coefficient of thermal expansion (CTE) by adjusting the volume fraction of diamond and the copper matrix, thereby reducing interfacial stress caused by temperature changes and preventing material cracking. Therefore, preferably, in the embodiments of this application, the diamond-metal composite layer uses a multi-layer metal mesh stacked and filled with diamond particles.

[0061] This application also provides a method for processing a diamond-metal composite material with six-sided metal coating, including the following steps:

[0062] Making a hexahedral metal box: Stamp and fold a metal sheet into a hexahedral metal box with a lid and an opening, and place it into a mold;

[0063] Select a metal mesh: Use a metal mesh with a uniform grid, the size of which is the same as the inner bottom surface size of the hexahedral metal box; lay the metal mesh inside the hexahedral metal box;

[0064] Diamond particle arrangement: Diamond particles with a surface coating are arranged in each grid of the metal mesh using a arranging machine;

[0065] Void filling: Place the hexahedral metal box and mold with diamond particles arranged on the vibration table, and spray metal powder of the same material as the metal mesh onto the metal mesh in vibration mode until the metal powder fills the voids of the metal mesh and reaches the same height as the metal mesh.

[0066] Multi-layer stacking: After the gap filling step, place a metal mesh inside the hexahedral metal box, repeat the diamond particle arrangement and gap filling steps until the metal mesh is level with the height of the hexahedral metal box, cover the top cover at the opening, and integrate the top cover with the metal box to obtain the preform.

[0067] Sintering: The above preforms are placed in a sintering furnace for sintering to obtain sintered composite materials.

[0068] In the processing method described in this application embodiment, when manufacturing a hexahedral metal box, the unfolded hexahedral shape is first punched out, with creases pre-cut at the edges; after folding along the edges, a hexahedral box is formed, and the edges are connected using a metal adhesive (such as nano-silver glue); the metal adhesive has a low shrinkage rate after curing, which can avoid dimensional deviations caused by thermal deformation. As another embodiment, when manufacturing a hexahedral metal box, a hexahedral unfolded shape is formed by laser cutting or wire cutting, with creases pre-cut at the edges; after folding along the edges, the edges are locally welded at the joints to combine adjacent edges.

[0069] In this embodiment, the metal mesh has a hexahedral or octahedral honeycomb structure to prevent mesh collapse during subsequent sintering and to maintain post-sintering warpage, while also shortening the heat conduction path of the metal matrix and maximizing the diamond-metal interface. In this application, the mesh wall thickness is 10–20 μm. Since the metal matrix exhibits shrinkage at high temperatures, reserving space offsets stress concentration caused by shrinkage and prevents diamond crushing. Therefore, it is necessary to control the gap between the mesh and the diamond particles. In this embodiment, the edge length L of the mesh is 10–20 μm larger than the particle size D of a single diamond particle. This 10–20 μm gap provides diffusion space for the metal coating on the diamond surface, which is beneficial for the formation of the interface layer and improves the material's shear strength.

[0070] In this application, a mechanical vibration table is used for vibration. Mechanical vibration achieves dense filling of metal powder and stable arrangement of diamond particles, while avoiding structural damage due to excessive vibration. Specifically, adjusting the vibration frequency controls the particle movement pattern. Controlling the vibration frequency to 5-15Hz promotes slow sliding of metal powder particles, preventing collisions between diamonds and the metal mesh and preventing diamond particle misalignment. Furthermore, the vibration frequency can be adjusted in two steps. For example, a low-frequency vibration of 5-10Hz is used in the initial stage to suit the initial loose filling stage. If the porosity is high, a higher frequency of 10-15Hz is used to compensate. The amplitude adjustment determines the filling impact energy. A smaller amplitude can eliminate porosity, suit a fine mesh, and make the surface metal powder more uniform. Excessive amplitude will cause metal powder splashing and loss. Therefore, in this application's embodiments, the amplitude is controlled at 0.1-0.5mm. The vibration time is mainly controlled to balance the filling effect. In this application's embodiments, the vibration time is controlled at 5-15 minutes.

[0071] Furthermore, in some embodiments of this application, electrostatic spraying technology is used to apply an electric field during gap filling, causing copper powder to be directionally filled into the grid gaps. The electric field voltage is 5-10kV. Through the 5-10kV high-voltage electric field, the charged metal powder is directionally moved along the electric field lines, accurately filling the gaps between diamond particles, solving the "shadow effect" of traditional vibration filling. The metal powder preferentially deposits in the grid corners with high electric field strength, forming an interlocking skeleton and improving compressive strength.

[0072] In embodiments employing copper foil shells, some examples use pure copper powder with a particle size of 0.5-5 μm. Ultrafine copper powder has a large specific surface area and high sintering driving force, which can lower the densification temperature. Other embodiments use mixed copper powder with added active ingredients. The purpose of adding active ingredients is to promote the diffusion and bonding of copper particles, lower the sintering temperature, reduce porosity, make the copper powder compatible with the copper matrix, and avoid the formation of brittle phases through interfacial reactions at high temperatures. Therefore, the active ingredient is selected from, but is not limited to, one or more of nano-Al2O3, nano-SiC, nano-TiC, nano-Y2O3, and nano-graphene, or a mixture of two or more of these. Hard particles such as nano-Al2O3 and nano-SiC (≤50nm) are embedded in the gaps between copper powder particles, hindering grain boundary migration (Zener pinning) and forcing copper atoms to diffuse rapidly along the particle surface, effectively reducing the sintering temperature. Graphene sheets form a three-dimensional conductive network, increasing local current density and inducing Joule heating during pulsed current sintering, accelerating the melting and bonding of copper particle surfaces. Y2O3 preferentially adsorbs oxygen impurities, inhibiting the formation of the Cu-O brittle phase, and reacts with the Ti coating on the diamond surface to form a Y-Ti-O transition layer, effectively improving interfacial shear strength. TiC's coefficient of thermal expansion is between that of copper and diamond, buffering thermal stress and preventing interfacial cracking of the composite material. For example, in some embodiments, the active ingredient is nano-Al2O3, used in amounts of 0.1-1.0 wt% of the copper powder. In other preferred embodiments, a two-component composite of nano-Al2O3 and nano-graphene is used, wherein the amounts of nano-Al2O3 and nano-graphene account for 0.2-0.3 wt% and 0.1-0.2 wt% of the weight of copper powder, respectively.

[0073] In some embodiments, when using copper foil to fabricate the metal casing, the sintering process employs vacuum hot pressing sintering. The vacuum level inside the furnace is <10 Pa, the hot pressing pressure is 20-40 MPa, the sintering temperature is 850-920℃, and the time is 55-65 min. In this method, the lower vacuum level prevents copper powder from oxidizing to Cu2O, ensuring a clean diamond-Ti coating interface and reducing interfacial thermal resistance. Simultaneously, the increased gas escape rate under vacuum enhances the growth rate of the copper powder sintering neck and shortens the densification time. Isotropic pressure is transmitted through a graphite mold, causing the copper powder to plastically flow and fill the gaps between the diamond particles, reducing porosity and improving thermal conductivity.

[0074] In other embodiments, where copper foil is used to fabricate the metal casing, the sintering process employs segmented sintering, including...

[0075] Pre-sintering: Pulse current assisted sintering is adopted, with a sintering temperature of 820-850℃, a pressure of 20-30MPa, a time of 10-20min, and a superimposed pulse current of 100-1000A with a frequency of 1-10Hz;

[0076] Final sintering: Hot pressing sintering combined with hydrogen atmosphere control is adopted. The sintering temperature is 880-900℃, the pressure is 30-40MPa, and the sintering time is 30-60min. The oxygen content in the H2 atmosphere is ≤10ppm.

[0077] The metal shell described in this application embodiment is an aluminum foil shell, the metal mesh is an aluminum mesh, and the metal powder used to fill the gaps is aluminum powder; the particle size of the aluminum powder is 0.5-5μm.

[0078] In the above-mentioned scheme using aluminum foil shell, the sintering pre-sintering is performed by using pulse current assisted sintering at a temperature of 520-550℃, a pressure of 20-30MPa, a time of 10-20min, and superimposed with a pulse current of 500-3000A.

[0079] Final sintering: Hot pressing sintering combined with hydrogen atmosphere control is adopted. The sintering temperature is 600-650℃, the pressure is 30-40MPa, and the sintering time is 30-60min. The oxygen content in the H2 atmosphere is ≤10ppm.

[0080] In addition to the two sintering methods mentioned above, other embodiments of this application may also employ sintering methods such as spark plasma sintering (SPS) and high temperature high pressure sintering (HTHP).

[0081] The six-sided metal-coated diamond-metal composite material described in this application is used in the fabrication of heat dissipation substrates for electronic devices. For example, it is used in various servers for IGBT heat dissipation and chip heat dissipation. It can also be applied in technical fields requiring high thermal conductivity and high strength materials, such as in the processing of high heat flux density electronic devices, for example, in the liquid cooling of AI servers, GPU clusters, and cloud computing and big data centers, as well as in the manufacture of GaN RF chips for 5G / 6G base stations and SiC inverter modules for electric vehicles; in the field of high-energy laser systems, for the manufacture of fiber laser pump couplers and solid-state laser crystal heat sinks; in the field of nuclear energy and fusion devices, for the manufacture of divertor targets for nuclear fusion reactors and plasma first walls; in the field of special power and energy equipment, for the manufacture of IGBT modules for electromagnetic catapult systems and contacts for high-voltage DC circuit breakers; in the aerospace field, for the beam spot region of electronic focusing systems and the periphery of laser molten pools in metal 3D printing; and in the quantum and superconducting fields, for the manufacture of microwave resonant cavities for superconducting qubits and room-temperature superconducting power transmission line connectors.

[0082] This application also provides a heat dissipation substrate for electronic devices, comprising a composite plate sintered from a hexahedral metal shell and at least one diamond-metal composite layer disposed within the metal shell; the diamond-metal composite layer comprises a metal mesh and diamond particles coated with a coating, the diamond particles being arranged in the mesh of the metal mesh, and the gaps between the mesh and the diamond particles being filled with metal powder; metal atoms in the metal mesh diffuse through the coating to the diamond surface, forming a mixing transition zone.

[0083] The following are some embodiments listed in this application, which further illustrate this application.

[0084] Example 1

[0085] This embodiment provides a six-sided copper-clad diamond-copper composite material, which is a composite material formed by sintering a six-sided copper foil shell and at least one diamond-copper composite layer placed in the copper foil shell; the diamond-copper composite layer includes a copper mesh and diamond particles with a coating on the surface, the diamond particles are arranged in the mesh of the copper mesh, and the gaps between the mesh and the diamond particles are filled with copper powder; Cu atoms in the copper mesh diffuse through the coating to the diamond surface to form a mixing transition zone.

[0086] As shown in Figure 4, the processing technology for six-sided copper-coated diamond / copper composite materials includes the following steps:

[0087] (1) A hexahedral unfolded shape is stamped out on a copper foil with a thickness of 250μm, and creases are reserved at the edges; the edges of the unfolded copper foil are glued with metal adhesive to form a copper foil box with a top cover and an open top surface; the copper foil box with the open top surface is placed into a graphite mold.

[0088] (2) A copper mesh with a regular hexahedral grid is used to place diamond particles. The mesh wall thickness is 15μm. The edge length of the regular hexahedron is 15μm larger than the particle size of the diamond particles placed therein. The size of the copper mesh plane is the same as the bottom surface of the copper foil box. Then the copper mesh is placed into the copper foil box.

[0089] (3) Using a layout machine, artificial CVD diamond particles with a 0.5μm Ti coating on the surface are arranged in each grid of the copper mesh, and the diamond particle size is 300μm.

[0090] (4) The copper foil box after diamond arrangement is placed together with the graphite mold on a mechanical vibration table. The vibration table is turned on with a vibration frequency of 10Hz and a vibration time of 10min, and the amplitude is controlled at 0.2mm. The copper powder is a mixed copper powder mixed with nano Al2O3, wherein the amount of nano Al2O3 accounts for 0.5wt% of the weight of the copper powder, and the particle size of the copper powder is 3μm. An electric field is applied by electrostatic spraying technology to make the copper powder directionally fill the mesh gaps of the copper mesh until the mixed copper powder fills the height of the entire copper mesh. The electric field voltage is 5kV.

[0091] (5) Place the second layer of copper mesh and repeat steps (3) and (4) above;

[0092] (6) After the four layers are stacked, the copper mesh is aligned with the height of the copper foil box. Then, the copper foil on the upper surface is covered and bonded to obtain the prefabricated part.

[0093] (7) The preform is subjected to vacuum hot pressing sintering with a vacuum degree of 1 Pa, a hot pressing pressure of 35 MPa, a sintering temperature of 900 °C, and a sintering time of 60 min to obtain a composite material with a sintered blank.

[0094] (8) Polish the surface of the sintered composite material to obtain a diamond-copper composite material with copper coating on six sides.

[0095] The performance of the six-sided copper-coated diamond / copper composite material described in Example 1 was tested. The standards, test items, and performance results are shown in Table 1.

[0096] The microstructure of the composite material cross section was observed using SEM, and the area ratio of diamond particles was statistically analyzed using ImageJ image analysis software. Combined with the particle size distribution calculation volume, the diamond volume fraction was determined.

[0097] The density measurement method is as follows: after grinding and polishing the sample cross section, observe the pore distribution under a microscope and calculate the pore area ratio by grid counting method; after cutting, mounting and polishing the sample, etch it with 4% nitric acid alcohol, take cross section images, and calculate the pore area ratio using software (ImageJ); density D = 1 - pore area ratio.

[0098] Table 1: Performance test results of Example 1

[0099] Based on Example 1 above, and with the diamond particle size remaining constant, the influence of the gap size between the mesh and the diamond particle size on the properties of the six-sided copper-coated diamond / copper composite material was further investigated. The difference between the mesh edge length and the diamond particle size was used as the evaluation condition, and other conditions were the same as in Example 1. The specific comparison results are shown in Table 2.

[0100] Table 2: Influence of the void size between the mesh and diamond particle size on the properties of composite materials

[0101] The results in Table 2 show that as the particle size difference increases (porosity increases), the thermal conductivity initially increases and then decreases, indicating improved interfacial bonding between diamond and the copper matrix, reduced interfacial thermal resistance, and increased thermal conductivity. However, when the particle size difference exceeds 15 μm, increased porosity leads to more interfacial defects, intensified phonon scattering, and a decrease in thermal conductivity. Increased particle size difference also reduces the filling efficiency of diamond particles, increases porosity, and continuously decreases the volume fraction of diamond. Density initially increases and then decreases with increasing particle size difference; smaller particle size differences result in more complete copper filling of pores during sintering, but increased porosity makes densification difficult, leading to decreased density. The coefficient of thermal expansion increases with increasing particle size difference, which is clearly related to the weakening of the copper-diamond interfacial bonding due to increased porosity, and the dominance of thermal expansion in the copper matrix. Therefore, based on the performance results in Table 2, in this embodiment, the edge length L of the mesh is controlled to be 10–20 μm larger than the particle size D of a single diamond particle, resulting in a six-sided copper-coated diamond / copper composite material with performance meeting application requirements. Preferably, when the edge length L of the control grid is 10 to 15 μm larger than the particle size D of a single diamond particle, the thermal conductivity, density, and coefficient of thermal expansion are all excellent.

[0102] Based on Example 1 above, the influence of diamond particle size on the properties of six-sided copper-coated diamond / copper composite materials was further investigated. Diamond particles of different sizes were selected, while other conditions remained the same as in Example 1. The specific comparison results are shown in Table 3.

[0103] Table 3: Effect of diamond particle size on the properties of six-sided copper-coated diamond / copper composites

[0104] Table 3 shows the changes in thermal conductivity, diamond volume fraction, density, and coefficient of thermal expansion of the six-sided copper-clad diamond / copper composite material under different diamond particle sizes. The data in Table 3 show that the thermal conductivity reaches its peak (890 W·m) when the diamond particle size increases to 250 μm. -1 ·K- 1However, when the particle size further increases to 300 μm, the thermal conductivity decreases slightly; this may be related to the fact that larger particles reduce the number of interfaces, leading to a decrease in interfacial thermal resistance. Both the diamond volume fraction and density increase significantly with increasing particle size. Diamond particles of suitable size not only occupy more volume themselves but also promote the densification and sintering of the composite material, reducing porosity. The coefficient of thermal expansion is negatively correlated with the diamond particle size. When the particle size increases from 100 μm to 300 μm, the coefficient of thermal expansion decreases from 7.1 ppm·K⁻¹ to 6.0 ppm·K⁻¹, indicating that larger diamond particles have a stronger restraining effect on the thermal expansion of the copper matrix, effectively limiting the macroscopic thermal expansion of the composite material. Preferably, in the embodiments of this application, a diamond particle size in the range of 200-250 μm can achieve comprehensive optimization of thermal conductivity, density, and coefficient of thermal expansion.

[0105] Based on Example 1 above, the influence of vibration conditions on the properties of six-sided copper-coated diamond / copper composite materials was further investigated. Different vibration conditions were selected, while other conditions remained the same as in Example 1. The specific comparison results are shown in Table 4.

[0106] Table 4: Effects of vibration conditions on the properties of six-sided copper-coated diamond / copper composites

[0107] Table 4 shows the changes in thermal conductivity, diamond volume fraction, density, and coefficient of thermal expansion of the composite material under different vibration frequencies and durations. According to the data in Table 4, increasing the vibration frequency is beneficial for improving thermal conductivity, diamond volume fraction, and density, while significantly reducing the coefficient of thermal expansion. While further increasing the vibration frequency can still improve thermal conductivity, it may adversely affect the diamond volume fraction and density, and the effect of reducing the coefficient of thermal expansion weakens. Therefore, in this application, the vibration frequency is controlled within the range of 2-10 Hz. At low frequencies, appropriately extending the vibration time can further improve the material properties; however, excessive vibration should be avoided to prevent the introduction of new defects or uneven particle distribution.

[0108] Based on Example 1 above, the effect of vacuum sintering temperature on the properties of six-sided copper-coated diamond / copper composite materials was further investigated. The vacuum sintering temperature was selected, while other conditions remained the same as in Example 1. Specific comparison results are shown in Table 5.

[0109] Table 5: Effect of vacuum sintering temperature on the properties of six-sided copper-coated diamond / copper composites

[0110] The data in Table 5 show that the thermal conductivity reaches its peak (868 W·m) at a vacuum sintering temperature of 900℃. -1 ·K- 1Subsequently, when the temperature was increased to 920℃ and 950℃, the thermal conductivity decreased to 815 W·m, respectively. -1 ·K- 1 The concentrations were 743 W·m⁻¹·K⁻¹. This indicates that the optimal sintering temperature range is 850-900℃. Regarding the effect on diamond volume fraction, the volume fraction decreased to 60.3% at 950℃, possibly related to diamond particle loss due to the diamond-copper interface reaction at high temperatures. The density reached its peak (99.5%) at 900℃, but slightly decreased to 98.6% at 950℃, indicating that over-sintering may lead to microstructure deterioration. The effect of sintering temperature on the coefficient of thermal expansion was as follows: the coefficient of thermal expansion first decreased and then increased with increasing sintering temperature. In the embodiments of this application, by controlling the sintering temperature within the range of 850-920℃, comprehensive optimization of thermal conductivity, density, and coefficient of thermal expansion can be achieved. Preferably, controlling the vacuum sintering temperature to 850-900℃ can balance thermal conductivity, density, and coefficient of thermal expansion.

[0111] Based on Example 1 above, the effect of hot pressing pressure on the properties of six-sided copper-coated diamond / copper composite materials during vacuum sintering was further investigated. Different hot pressing pressures were selected, while other conditions remained the same as in Example 1. The specific comparison results are shown in Table 6.

[0112] Table 6: Effect of hot pressing pressure on the properties of six-sided copper-coated diamond / copper composite materials

[0113] Table 6 shows that thermal conductivity, diamond volume fraction, and density all peak at 25 MPa, while the coefficient of thermal expansion reaches its lowest value of 6.0 ppm·K⁻¹ at 25 MPa. The significant influence of hot-pressing pressure on the properties of the six-sided copper-clad diamond / copper composite material is mainly reflected in three aspects: interfacial bonding, particle fragmentation, and densification behavior. By controlling the hot-pressing pressure within the range of 20-30 MPa, comprehensive optimization of thermal conductivity, density, and coefficient of thermal expansion can be achieved. Preferably, a hot-pressing pressure of 20-30 MPa results in excellent balance between thermal conductivity, density, and coefficient of thermal expansion.

[0114] Based on Example 1 above, the influence of copper powder composition on the properties of six-sided copper-coated diamond / copper composite materials during vacuum sintering was further investigated. Different copper powder compositions were selected, while other conditions remained the same as in Example 1. The specific comparison results are shown in Table 7.

[0115] Table 7: Effect of copper powder composition on the properties of six-sided copper-coated diamond / copper composite materials

[0116] Table 7 shows that, compared to pure copper powder, the thermal conductivity, diamond volume fraction, and density of the composite material with added Al2O3 or Al2O3+graphene are significantly improved, while the coefficient of thermal expansion is significantly reduced. This demonstrates that Al2O3 and graphene, as reinforcing phases, can significantly improve the thermal conductivity and diamond volume fraction of the composite material. In the embodiments of this application, by adding appropriate amounts of reinforcing phases such as Al2O3 and graphene, the thermal conductivity, diamond volume fraction, and density of the composite material can be significantly improved, while the coefficient of thermal expansion is reduced. Among these, the composition of copper powder + 0.2wt% Al2O3 + 0.2wt% graphene exhibits the best overall performance and is an ideal choice for preparing high-performance six-sided copper-clad diamond / copper composite materials.

[0117] Example 2

[0118] This embodiment provides a six-sided copper-clad diamond / copper composite material, which is a composite material formed by sintering a hexahedral metal shell and at least one diamond-copper composite layer placed in the metal shell; the diamond-copper composite layer includes a copper mesh and diamond particles with a coating on the surface, the diamond particles are arranged in the mesh of the copper mesh, and the gaps between the mesh and the diamond particles are filled with copper powder; Cu atoms in the copper mesh diffuse through the coating to the diamond surface, forming a mixing transition zone.

[0119] The processing technology for six-sided copper-coated diamond / copper composite materials specifically includes the following steps:

[0120] (1) A hexahedral unfolded shape is stamped out on a copper foil with a thickness of 350μm, and creases are reserved at the edges; the edges of the unfolded copper foil are glued with metal adhesive to form a copper foil box with a top cover and an open top surface; the copper foil box with the open top surface is placed into a graphite mold.

[0121] (2) A copper mesh with a regular hexahedral grid is used to place diamond particles. The mesh wall thickness is 20μm. The edge length of the regular hexahedron is 20μm larger than the particle size of the diamond particles placed therein. The size of the copper mesh plane is the same as the bottom surface of the copper foil box. Then the copper mesh is placed into the copper foil box.

[0122] (3) Using a arranging machine, artificial CVD diamond particles with a Ti and Cr composite coating on the surface are arranged in each grid of the copper mesh. The coating thickness is 0.3 μm and the diamond particle size is 500 μm.

[0123] (4) The metal box after diamonds are arranged is placed together with the graphite mold on a mechanical vibration table. The vibration table is turned on with a vibration frequency of 5Hz, a vibration time of 15min, and an amplitude of 0.5mm. The copper powder is a mixed copper powder mixed with nano Al2O3, wherein the amount of nano Al2O3 accounts for 1.0wt% of the weight of the copper powder, and the copper powder particle size is 3μm. An electric field is applied by electrostatic spraying technology to make the copper powder fill the mesh gaps of the copper mesh in an oriented manner until the mixed copper powder fills the height of the entire copper mesh. The electric field voltage is 5kV.

[0124] (5) Place the second layer of copper mesh and repeat steps (3) and (4) above;

[0125] (6) After the three layers are stacked, the copper mesh is level with the height of the metal box. Then, the copper foil on the upper surface is covered and bonded to obtain the prefabricated part.

[0126] (7) The preform is subjected to sintering, including,

[0127] Pre-sintering: Pulse current assisted sintering was used, with a sintering temperature of 820℃, a pressure of 25MPa, a time of 15min, and a superimposed 500A pulse current at a frequency of 5Hz.

[0128] Final sintering: Hot pressing sintering combined with hydrogen atmosphere control is adopted. The sintering temperature is 900℃, the pressure is 35MPa, and the sintering time is 50min. The oxygen content in the H2 atmosphere is ≤10ppm.

[0129] (8) Polish the surface of the sintered composite material to obtain a six-sided copper-coated diamond / copper composite material.

[0130] The performance of the six-sided copper-coated diamond / copper composite material described in Example 2 was tested. The standards, test items, and performance results are shown in Table 1.

[0131] Table 8: Performance test results of Example 2

[0132] Based on Example 2 above, the effects of pre-sintering and final sintering temperatures on the properties of six-sided copper-clad diamond / copper composite materials were further investigated. Different pre-sintering and final sintering temperatures were selected, while other conditions remained the same as in Example 2. The specific comparison results are shown in Table 9.

[0133] Table 9: Effects of pre-sintering and final sintering temperatures on the properties of six-sided copper-clad diamond / copper composites

[0134] The results in Table 9 show that the final sintering temperature is the key factor determining the material properties, while the pre-sintering temperature has a synergistic effect on the final properties by influencing the initial microstructure. In the embodiments of this application, by optimizing the sintering temperature regime (pre-sintering at 820℃ + final sintering at 900℃), the optimal balance between thermal conductivity, diamond volume fraction, and coefficient of thermal expansion can be achieved. Final sintering temperatures above 900℃ may lead to diamond graphitization and interface degradation, requiring performance compensation through process optimization (such as atmosphere protection and post-treatment).

[0135] Comparative Example 1

[0136] This embodiment provides a six-sided copper-coated diamond / copper composite material, which differs from Embodiment 1 in that: step (4) does not use vibration to fill copper powder, but instead places 15μm copper foil between each layer of copper mesh.

[0137] The performance of the six-sided copper-coated diamond / copper composite material of Comparative Example 1 was tested according to the testing method of Example 1. The results are shown in Table 10.

[0138] Table 10: Performance test results of Comparative Example 1

[0139] Example 3

[0140] This embodiment provides a six-sided aluminum-coated diamond-aluminum composite material, which is a composite material formed by sintering a six-sided aluminum foil shell and at least one diamond-aluminum composite layer placed in the aluminum foil shell; the diamond-aluminum composite layer includes an aluminum mesh and diamond particles with a coating on the surface, the diamond particles are arranged in the mesh of the aluminum mesh, and the gaps between the mesh and the diamond particles are filled with aluminum powder; Cu atoms in the aluminum mesh diffuse through the coating to the diamond surface, forming a mixing transition zone.

[0141] The processing technology for six-sided aluminum-coated diamond-aluminum composite materials specifically includes the following steps:

[0142] (1) A hexahedral unfolded shape is stamped out on an aluminum foil with a thickness of 250μm, and creases are reserved at the edges; the edges of the unfolded aluminum foil are glued with metal adhesive to form an aluminum foil box with a top cover and an open top surface; the aluminum foil box with the open top surface is placed into a graphite mold.

[0143] (2) An aluminum mesh with a regular hexahedral grid is used to place diamond particles. The mesh wall thickness is 15μm, and the edge length of the regular hexahedron is 15μm larger than the particle size of the diamond particles placed therein. The size of the aluminum mesh plane is the same as the bottom surface of the aluminum foil box. Then the aluminum mesh is placed into the aluminum foil box.

[0144] (3) Using a layout machine, artificial CVD diamond particles with a 0.5μm Ti coating on the surface are arranged in each grid of the aluminum mesh, and the diamond particle size is 300μm.

[0145] (4) After the diamonds are arranged, the aluminum foil box and the graphite mold are placed together on the mechanical vibration table. The vibration table is turned on with a vibration frequency of 10Hz and a vibration time of 10min. The amplitude is controlled at 0.2mm. The electrostatic spraying technology is used to apply an electric field to make the aluminum powder fill the mesh gaps of the aluminum mesh in a directional manner until the mixed aluminum powder fills the entire height of the aluminum mesh. The electric field voltage is 5kV.

[0146] (5) Place the second layer of aluminum mesh and repeat steps (3) and (4) above;

[0147] (6) After the three layers are stacked, the aluminum mesh is aligned with the height of the aluminum foil box. Then, the aluminum foil on the upper surface is covered and bonded to obtain the prefabricated part.

[0148] (7) The preform is subjected to vacuum hot pressing sintering, using segmented sintering, including,

[0149] Pre-sintering: Pulse current assisted sintering was used, with a sintering temperature of 520℃, a pressure of 20MPa, a time of 10min, and a superimposed pulse current of 500A.

[0150] Final sintering: Hot pressing sintering combined with hydrogen atmosphere control was adopted. The sintering temperature was 600℃, the pressure was 30MPa, and the sintering time was 60min. The oxygen content in the H2 atmosphere was ≤10ppm. The resulting composite material was formed from the sintered blank.

[0151] (8) Polish the surface of the sintered composite material to obtain a diamond-aluminum composite material with aluminum coating on six sides.

[0152] The performance of the six-sided aluminum-coated diamond-aluminum composite material described in Example 3 was tested. The standards, test items, and performance results are shown in Table 11.

[0153] The microstructure of the composite material cross section was observed using SEM, and the area ratio of diamond particles was statistically analyzed using ImageJ image analysis software. Combined with the particle size distribution calculation volume, the diamond volume fraction was determined.

[0154] The density measurement method is as follows: after grinding and polishing the sample cross section, observe the pore distribution under a microscope and calculate the pore area ratio by grid counting method; after cutting, mounting and polishing the sample, etch it with 4% nitric acid alcohol, take cross section images, and calculate the pore area ratio using software (ImageJ); density D = 1 - pore area ratio.

[0155] Table 11: Performance test results of Example 3

[0156] Example 4

[0157] This embodiment provides a six-sided aluminum-coated diamond-aluminum composite material, which is a composite material formed by sintering a six-sided aluminum foil shell and at least one diamond-aluminum composite layer placed in the aluminum foil shell; the diamond-aluminum composite layer includes an aluminum mesh and diamond particles with a coating on the surface, the diamond particles are arranged in the mesh of the aluminum mesh, and the gaps between the mesh and the diamond particles are filled with aluminum powder; Cu atoms in the aluminum mesh diffuse through the coating to the diamond surface, forming a mixing transition zone.

[0158] The processing technology for six-sided aluminum-coated diamond-aluminum composite materials specifically includes the following steps:

[0159] (1) A hexahedral unfolded shape is stamped out on an aluminum foil with a thickness of 250μm, and creases are reserved at the edges; the edges of the unfolded aluminum foil are glued with metal adhesive to form an aluminum foil box with a top cover and an open top surface; the aluminum foil box with the open top surface is placed into a graphite mold.

[0160] (2) An aluminum mesh with a regular hexahedral grid is used to place diamond particles. The mesh wall thickness is 10μm, and the edge length of the regular hexahedron is 20μm larger than the particle size of the diamond particles placed therein. The size of the aluminum mesh plane is the same as the bottom surface of the aluminum foil box. Then the aluminum mesh is placed into the aluminum foil box.

[0161] (3) Using a layout machine, artificial CVD diamond particles with a 0.5μm Cr coating on the surface are arranged in each grid of the aluminum mesh, and the diamond particle size is 300μm.

[0162] (4) After the diamonds are arranged, the aluminum foil box and the graphite mold are placed together on the mechanical vibration table. The vibration table is turned on with a vibration frequency of 5Hz and a vibration time of 20min. The amplitude is controlled at 0.5mm. The electrostatic spraying technology is used to apply an electric field to make the aluminum powder fill the mesh gaps of the aluminum mesh in a directional manner until the mixed aluminum powder fills the entire height of the aluminum mesh. The electric field voltage is 10kV.

[0163] (5) Place the second layer of aluminum mesh and repeat steps (3) and (4) above;

[0164] (6) After the four layers are stacked, the aluminum mesh is aligned with the height of the aluminum foil box. Then, the aluminum foil on the upper surface is covered and bonded to obtain the prefabricated part.

[0165] (7) The preform is subjected to vacuum hot pressing sintering, using segmented sintering, including,

[0166] Pre-sintering: Pulse current assisted sintering was used, with a sintering temperature of 550℃, a pressure of 25MPa, a time of 15min, and an 800A pulse current superimposed.

[0167] Final sintering: Hot pressing sintering combined with hydrogen atmosphere control was adopted. The sintering temperature was 650℃, the pressure was 35MPa, and the sintering time was 40min. The oxygen content in the H2 atmosphere was ≤10ppm. The resulting composite material was formed from the sintered blank.

[0168] (8) Polish the surface of the sintered composite material to obtain a diamond-aluminum composite material with aluminum coating on six sides.

[0169] The performance of the six-sided aluminum-coated diamond-aluminum composite material described in Example 4 was tested. The standards, test items, and performance results are shown in Table 12.

[0170] The microstructure of the composite material cross section was observed using SEM, and the area ratio of diamond particles was statistically analyzed using ImageJ image analysis software. Combined with the particle size distribution calculation volume, the diamond volume fraction was determined.

[0171] The density measurement method is as follows: after grinding and polishing the sample cross section, observe the pore distribution under a microscope and calculate the pore area ratio by grid counting method; after cutting, mounting and polishing the sample, etch it with 4% nitric acid alcohol, take cross section images, and calculate the pore area ratio using software (ImageJ); density D = 1 - pore area ratio.

[0172] Table 12: Performance test results of Example 4

[0173] The above embodiments are merely preferred embodiments of the present invention and should not be construed as limiting the scope of protection of the present invention. Any non-substantial changes and substitutions made by those skilled in the art based on the present invention shall fall within the scope of protection claimed by the present invention.

Claims

1. A six-sided metal-coated diamond-metal composite, characterized by, It is a composite material formed by sintering a hexahedral metal shell and at least one diamond-metal composite layer placed in the metal shell; the diamond-metal composite layer includes a metal mesh and diamond particles with a coating on the surface, the diamond particles are arranged in the mesh of the metal mesh, and the gaps between the mesh and the diamond particles are filled with metal powder; the metal atoms in the metal mesh diffuse through the coating to the diamond surface to form a mixing transition zone.

2. The six-sided coated metal diamond-metal composite of claim 1, wherein, The mesh is a regular hexahedral or regular octahedral honeycomb structure with a wall thickness of 10-20 μm and an edge length L that is 10-20 μm larger than the particle size D of a single diamond particle.

3. The six-sided coated metal diamond-metal composite of claim 2, wherein, The diamond is one or more of the following: synthetic high-temperature and high-pressure diamond, synthetic CVD diamond, or natural diamond, and the diamond particle size is 100-1000 μm.

4. The six-sided coated metal diamond-metal composite of claim 1, wherein, The mixed transition region is a ternary phase formed by metal-coating material-C, with a thickness of 1-2 μm.

5. The six-sided coated metal diamond-metal composite of claim 1, wherein, The coating is a coating formed from one of the materials Ti, Cr, W, V, and Zr, or a composite coating formed from two or more materials; the thickness of the coating is 0.1 to 0.5 μm.

6. The six-sided metal-coated diamond-metal composite of any one of claims 1-5, wherein, The metal outer shell is an aluminum foil shell, and the metal mesh and metal powder are both made of aluminum; there is a 3-8 nm aluminum oxide nanolayer at the interface between the aluminum foil shell and the diamond.

7. The six-sided metal-coated diamond-metal composite of any one of claims 1-5, wherein the metal coating is a metal alloy. The metal outer shell is a copper foil shell, and the metal mesh and metal powder are both made of copper; the surface of the copper foil shell is a nanocrystalline copper layer with a grain size of 50-100nm; the interior is a coarse-grained copper matrix with a grain size of 5-10μm.

8. A method of processing a diamond-metal composite of claim 1 to 7, wherein Includes the following steps, Making a hexahedral metal box: Stamp and fold a metal sheet into a hexahedral metal box with a lid and an opening, and place it into a mold; Select a metal mesh: Use a metal mesh with a uniform grid, the size of which is the same as the inner bottom surface size of the hexahedral metal box; lay the metal mesh inside the hexahedral metal box; Diamond particle arrangement: Diamond particles with a surface coating are arranged in each grid of the metal mesh using a arranging machine; Void filling: Place the hexahedral metal box and mold with diamond particles arranged on the vibration table, and spray metal powder of the same material as the metal mesh onto the metal mesh in vibration mode until the metal powder fills the voids of the metal mesh and reaches the same height as the metal mesh. Multi-layer stacking: After the gap filling step, place a metal mesh inside the hexahedral metal box, repeat the diamond particle arrangement and gap filling steps until the metal mesh is level with the height of the hexahedral metal box, cover the top cover at the opening, and integrate the top cover with the metal box to obtain the preform. Sintering: The above preforms are placed in a sintering furnace for sintering to obtain sintered composite materials.

9. The method of claim 8, wherein, When making a hexahedral metal box, first punch out the unfolded hexahedral shape, leaving creases at the edges; fold along the edges to form a hexahedral box, and connect the edges with metal adhesive.

10. According to the processing method of claim 8, when making a hexahedral metal box, a hexahedral unfolded shape is formed by laser cutting or wire cutting, and creases are pre-etched at the edges; after folding along the edges, the edges are locally welded at the joint to combine adjacent edges.

11. The method of claim 10, wherein, The metal mesh has a hexahedral or octahedral honeycomb structure, and the edge length L of the mesh is 10-20 μm larger than the particle size D of a single diamond particle.

12. The method of claim 8, wherein, The vibration table is a mechanical vibration table with a vibration frequency of 2-10Hz, a vibration time of 5-20min, and an amplitude of 0.2-0.5mm.

13. The method of claim 12, wherein, When filling the gaps, an electric field is applied using electrostatic spraying technology to orient the metal powder into the mesh gaps, with an electric field voltage of 5-10kV.

14. The method of claim 8, wherein, The metal outer shell is a copper foil shell, the metal mesh is a copper mesh, and the metal powder used to fill the gaps is pure copper powder or mixed copper powder with mixed active ingredients; the particle size of the copper powder is 0.5-5μm.

15. The method of claim 14, wherein, The active ingredient is one or more of nano-Al2O3, nano-SiC, nano-TiC, nano-Y2O3, and nano-graphene, and the amount of the active ingredient accounts for 0.1-1.0 wt% of the weight of the copper powder.

16. The method of claim 14, wherein The sintering process employs vacuum hot pressing sintering, with a vacuum level of <10Pa, a hot pressing pressure of 20-40MPa, a sintering temperature of 850-920℃, and a sintering time of 55-65min.

17. The method of claim 14, wherein, The sintering process employs segmented sintering, including: Pre-sintering: Pulse current assisted sintering is adopted, with a sintering temperature of 820-850℃, a pressure of 20-30MPa, a time of 10-20min, and a superimposed pulse current of 100-1000A with a frequency of 1-10Hz; Final sintering: Hot pressing sintering combined with hydrogen atmosphere control is adopted. The sintering temperature is 880-900℃, the pressure is 30-40MPa, and the sintering time is 30-60min. The oxygen content in the H2 atmosphere is ≤10ppm.

18. The method of claim 8, wherein, The metal outer shell is an aluminum foil shell, the metal mesh is an aluminum mesh, and the metal powder used to fill the gaps is aluminum powder; the particle size of the aluminum powder is 0.5-5μm.

19. The method of claim 18, wherein, The sintering process employs segmented sintering, including: Pre-sintering: Pulse current assisted sintering is adopted, with a sintering temperature of 520-550℃, a pressure of 20-30MPa, a time of 10-20min, and a pulse current of 500-3000A superimposed. Final sintering: Hot pressing sintering combined with hydrogen atmosphere control is adopted. The sintering temperature is 600-650℃, the pressure is 30-40MPa, and the sintering time is 30-60min. The oxygen content in the H2 atmosphere is ≤10ppm.

20. The method of claim 8, wherein, It also includes a step of surface polishing the sintered composite material.

21. The application of the six-sided metal-coated diamond-metal composite material as described in any one of claims 1-7 in the fabrication of heat dissipation components for electronic devices.

22. An electronic device heat spreading substrate, characterized by, The composite plate comprises a hexahedral metal shell and at least one diamond-metal composite layer placed within the metal shell, sintered together; the diamond-metal composite layer encloses a metal mesh and diamond particles with a coating on their surface, the diamond particles being arranged in the mesh of the metal mesh, and the gaps between the mesh and the diamond particles being filled with metal powder; metal atoms in the metal mesh diffuse through the coating to the diamond surface, forming a mixing transition zone.

Images