Graphene composite high-thermal-conductivity aluminum substrate, preparation method and application

Abstract

The invention belongs to the technical field of metal substrates, and particularly relates to a graphene composite high-thermal-conductivity aluminum substrate, a preparation method and application. The graphene composite high-thermal-conductivity aluminum substrate comprises a conductive copper foil layer, a graphene composite high-thermal-conductivity layer and an aluminum substrate layer, the graphene composite high heat conduction layer comprises an upper layer, a middle layer and a lower layer, and the upper layer is connected with the conductive copper foil layer and is a heat conduction adhesive layer; the middle layer is a graphene composite sheet layer and is a film layer formed by compounding and hot-pressing graphene and a polymer; the lower layer is connected with the aluminum substrate layer and is a graphene modified aluminum oxide film layer; graphene in the graphene composite sheet layer is arranged in a horizontal orientation manner; graphene in the aluminum oxide film layer is arranged in a vertical orientation manner. According to the graphene composite high-thermal-conductivity aluminum substrate and the preparation method thereof, the graphene is used for constructing a longitudinal efficient heat conduction path and balancing stress, and the obtained graphene composite high-thermal-conductivity aluminum substrate has ultrahigh heat conduction performance, ultralow warping rate and good reliability and can be used in high-performance electronic devices and circuit boards.

Description

Technical Field

[0001] This invention belongs to the field of metal substrate technology, specifically relating to a graphene composite high thermal conductivity aluminum substrate, its preparation method, and its application. Background Technology

[0002] As electronic devices evolve towards higher performance, miniaturization, and higher integration, heat dissipation has become a key factor restricting the performance and reliability of electronic devices. Aluminum substrates, as a type of metal-based copper-clad laminate, have become the mainstream heat dissipation material due to their excellent thermal conductivity, lightweight nature, and cost advantages. Traditional single-sided aluminum substrates typically consist of a three-layer structure: a circuit layer (copper foil), an insulating layer, and a metal base layer. However, with technological advancements, several drawbacks have become increasingly apparent. For example, due to the inherent limitations of thermal conductivity, the thermal conductivity of traditional aluminum substrates is insufficient to meet the heat dissipation requirements of high-performance and miniaturized electronic devices. Furthermore, during the lamination process, the mismatch in thermal expansion coefficients between materials generates internal stress, easily leading to board warping and other issues that directly affect the performance of the aluminum substrate.

[0003] Graphene, as a two-dimensional nanomaterial, has extremely high thermal conductivity, making it an ideal material for thermal management. While existing technologies employ graphene to improve thermal conductivity, most methods simply involve incorporating it into insulating adhesives or using it as a surface coating, failing to fundamentally construct efficient vertical thermal conduction pathways and balance stress.

[0004] Therefore, it is of great significance to develop a graphene composite high thermal conductivity aluminum substrate that can meet the high performance requirements of today's electronic devices. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a graphene composite high thermal conductivity aluminum substrate, its preparation method, and its application. This graphene composite high thermal conductivity aluminum substrate has ultra-high thermal conductivity, ultra-low warpage, and good reliability, and can be used in high-performance electronic devices and circuit boards.

[0006] To achieve the above objectives, the present invention provides the following technical solution: The first objective of this invention is to provide a graphene composite high thermal conductivity aluminum substrate, comprising a conductive copper foil layer, a graphene composite high thermal conductivity layer, and an aluminum substrate layer; the graphene composite high thermal conductivity layer comprises an upper layer, a middle layer, and a lower layer, wherein the upper layer is connected to the conductive copper foil layer and is a thermally conductive adhesive layer; the middle layer is a graphene composite sheet layer, which is a film layer formed by hot pressing graphene and a polymer composite; and the lower layer is connected to the aluminum substrate layer and is a graphene-modified alumina film layer. The graphene in the graphene composite sheet is arranged in a horizontal orientation. The graphene in the alumina film is arranged in a vertical orientation.

[0007] This invention optimizes the thermally conductive layer structure between the electroplated copper foil layer and the aluminum substrate layer, designing it as a three-dimensional, high-efficiency thermally conductive structure with three different materials. The alumina film layer connected to the aluminum substrate layer is modified with vertically oriented graphene, which can covalently bond with the aluminum substrate, reducing interfacial thermal resistance. Furthermore, the vertically oriented graphene provides excellent longitudinal thermal conductivity pathways. The middle graphene composite sheet layer combines high-temperature resistant polymers with horizontally oriented graphene, providing not only high in-plane thermal conductivity but also an extremely low horizontal coefficient of thermal expansion, balancing warpage. The upper layer is a thermally conductive adhesive layer connected to the electroplated copper foil layer. The resulting graphene composite high thermal conductivity aluminum substrate exhibits ultra-high thermal conductivity, ultra-low warpage, and high reliability.

[0008] Further, in the above technical solution, the preparation method of the graphene composite sheet is as follows: Graphene sheets are soaked in a mixed solution of concentrated sulfuric acid and hydrogen peroxide and ball-milled for 2-3 hours, neutralized with sodium hydroxide to neutral, filtered, and dried; the pretreated graphene sheets are dispersed in a polyamic acid solution and ultrasonically mixed into a uniform slurry; the slurry is placed in a strong magnetic field and coated into a cast film; after the graphene in the film is highly oriented horizontally, it is subjected to a stepped heat treatment under an inert atmosphere, and then stretched at 25-30 MPa for 2-15 minutes to obtain the final product. This technical solution first uses acid treatment to improve the dispersion performance of graphene; then, the strong magnetic field guides the graphene sheets to be oriented horizontally, which maximizes the utilization of the high in-plane thermal conductivity of graphene, avoids heat accumulation, and after mixing with the polymer, it can also reduce the coefficient of thermal expansion of the composite layer, effectively balance thermal stress, and suppress warping.

[0009] Furthermore, in the above technical solution, the graphene sheet is a large-diameter graphene oxide sheet; the concentrated sulfuric acid and hydrogen peroxide mixed solution is a mixed solution with a volume ratio of 98% concentrated sulfuric acid and 30% hydrogen peroxide of 1-5:1; the solid-liquid ratio of the graphene sheet to the concentrated sulfuric acid and hydrogen peroxide mixed solution is 1:5-10; the solid-liquid ratio of the graphene sheet dispersed in the polyamic acid solution is 1:5-20; and the ultrasonic frequency is 20-35kHz.

[0010] Furthermore, in the above technical solution, the process of performing stepped heat treatment is as follows: first, hold at 110-130℃ for 5-10 hours, then hold at 280-300℃ for 5-10 hours, then hold at 800-1000℃ for 5-10 hours, and finally treat at 1500-2000℃ for 1-2 hours.

[0011] Furthermore, in the above technical solution, the raw materials of the thermally conductive adhesive layer include, by weight, 100-120 parts epoxy resin, 3-10 parts nanodiamond powder, 150-200 parts aluminum nitride or boron nitride, 10-20 parts curing agent, and 0.5-1.5 parts coupling agent; the particle size of the nanodiamond powder is 40-80 nm; the curing agent is diaminodiphenylmethane; and the coupling agent is a silane coupling agent. In this technical solution, aluminum nitride or boron nitride and a small amount of nanodiamond are mixed into the thermally conductive adhesive layer as thermally conductive fillers. Simultaneously, the isotropic thermal conductivity of the sp3 hybrid carbon structure of nanodiamond is utilized to further improve the longitudinal thermal conductivity.

[0012] The second objective of this invention is to provide a method for preparing a graphene-composite high thermal conductivity aluminum substrate, comprising the following steps: (1) Clean and degrease the aluminum substrate layer; (2) A porous anodic aluminum oxide film is generated on the surface of an aluminum substrate by electrochemical anodizing process, and graphene is vertically grown on the porous anodic aluminum oxide film by chemical vapor deposition process to obtain an aluminum oxide film layer on the aluminum substrate layer. (3) Mix the raw materials of the thermally conductive adhesive layer according to the ratio, and disperse them by high-speed stirring and ball milling to make thermally conductive adhesive paste. Apply it to the release film by coating machine, and heat and dry the solvent in the oven and semi-cur it to form a thermally conductive adhesive layer. (4) Prepare graphene composite sheets and copper foil layers; (5) First, a thin layer of adhesive is coated on the aluminum substrate with an aluminum oxide film layer, and then graphene composite sheet, thermally conductive adhesive layer and copper foil layer are stacked in sequence from bottom to top. Then, the composite board is obtained by hot pressing composite process. Specifically, the adhesive used can be thermally conductive paste or silicone thermally conductive adhesive prepared according to the above method. (6) The composite plate is processed by a side-entry laser processing system to obtain a graphene composite high thermal conductivity aluminum substrate.

[0013] This invention designs the thermal conductive layer structure between the copper foil layer and the aluminum substrate layer as a three-dimensional high-efficiency thermal conductive structure with three different materials. The thermal conductive materials graphene in each layer are oriented to maximize the thermal conductivity. Finally, the side-entry laser processing can improve the utilization rate while effectively releasing and offsetting the residual stress caused by the mismatch of the internal thermal expansion coefficients of the materials, further improving the warping problem.

[0014] Furthermore, in step (2) of the above technical solution, the electrochemical anodizing process is as follows: a mixed solution of 15% sulfuric acid, 1% oxalic acid, and 0.05% boric acid with a mass concentration of 1.5 A / dm³ is used as the electrolyte. 2Anodizing of the aluminum substrate layer at 18℃ for 1 hour produces a porous anodic aluminum oxide film with a thickness of 30-50μm. The chemical vapor deposition process is as follows: the aluminum substrate layer with the porous anodic aluminum oxide film is placed in a CVD furnace, methane is introduced, and graphene is grown in the pores of the porous anodic aluminum oxide film at 900℃.

[0015] Furthermore, in step (4) of the above technical solution, the hot-pressing composite process is divided into three stages, which are carried out in a vacuum environment. Specifically, in the first stage, the hot-pressing composite process is carried out at 80-100℃ and 5-10MPa for 20-30 minutes; in the second stage, the hot-pressing composite process is carried out at 150-180℃ and 15-20MPa for 60-80 minutes; in the third stage, the hot-pressing composite process is carried out at 50℃ or below, the pressure is released, and the composite plate is removed.

[0016] Furthermore, in step (5) of the above technical solution, the side-entry laser processing is as follows: a V-shaped groove of a certain depth is pre-opened on the side of the composite plate, and a precision laser source is used to scan and erode the V-shaped groove from the side to obtain the required aluminum substrate; the laser source is an ultraviolet laser with a wavelength of 355nm, a power of 20-30W, and a scanning speed of 200-500mm / s.

[0017] A third objective of this invention is to provide an application of the graphene composite high thermal conductivity aluminum substrate described above in electronic devices and circuit boards.

[0018] Compared with the prior art, the beneficial effects of the present invention are as follows: The thermally conductive layer structure designed in this invention is a three-dimensional high-efficiency thermally conductive structure composed of three layers of different materials. The alumina film layer connected to the aluminum substrate layer is modified with vertically oriented graphene, which not only covalently bonds with the aluminum substrate to reduce interfacial thermal resistance, but also provides excellent longitudinal thermal conductivity pathways, greatly improving thermal conductivity. The middle graphene composite sheet layer combines horizontally oriented graphene with high-temperature resistant polymers, which not only provides high in-plane thermal conductivity, but also provides an extremely low coefficient of thermal expansion in the horizontal direction, balancing warpage. The upper layer is a thermally conductive adhesive layer connected to the electrolytic copper foil layer. By introducing nanodiamond with isotropic thermal conductivity, the thermal conductivity can be further improved. The resulting three-dimensional high-efficiency thermally conductive structure constructs a longitudinally efficient thermal conductivity pathway and balances stress, effectively solving the warpage problem by balancing high thermal conductivity and stress.

[0019] After pressing the various layers of materials together, the present invention further utilizes side-entry laser processing, which not only improves the utilization rate but also effectively releases and counteracts the residual stress caused by the mismatch of the internal thermal expansion coefficients of the materials, further improving the warping problem.

[0020] The graphene composite high thermal conductivity aluminum substrate prepared by this invention has ultra-high thermal conductivity, ultra-low warpage, and good reliability. It can be applied to electronic devices and circuit boards and has broad application prospects. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the graphene composite high thermal conductivity aluminum substrate of the present invention; Figure 2 This is a schematic diagram of the structure of the graphene composite high thermal conductivity layer of the present invention.

[0022] Explanation of the labels in the diagram: 1. Aluminum substrate layer; 2. Graphene composite high thermal conductivity layer; 3. Electroplated copper foil layer; 201. Alumina film layer; 202. Graphene composite sheet layer; 203. Thermally conductive adhesive layer. Detailed Implementation

[0023] Unless otherwise specified, the experimental methods used in the following examples are conventional methods. Unless otherwise specified, the raw materials used in the following examples are all commercially available products and can be purchased from the market.

[0024] The above-described technical features of the present invention and the technical features specifically described below (such as in the embodiments) can be combined with each other to form new or preferred technical solutions.

[0025] The raw materials involved in the various embodiments of the present invention are either existing commercially available products or can be prepared according to existing methods, and the testing methods are industry-standard methods.

[0026] Example 1 A method for preparing a graphene-composite high thermal conductivity aluminum substrate includes the following steps: (1) Clean and degrease the aluminum substrate layer, and prepare the electroplated copper foil layer at the same time; (2) A mixed solution of 15% sulfuric acid, 1% oxalic acid, and 0.05% boric acid was used as the electrolyte, at a concentration of 1.5 A / dm³. 2 Anodizing of the aluminum substrate layer at 18℃ for 1 hour produces a porous anodic aluminum oxide film with a thickness of 30μm. Using chemical vapor deposition, the aluminum substrate layer with the porous anodic aluminum oxide film is placed in a CVD furnace, methane is introduced, and graphene is vertically grown in the pores of the porous anodic aluminum oxide film at 900℃ to obtain an aluminum oxide film layer 201 on the aluminum substrate. (3) Mix the raw materials of the thermally conductive adhesive layer according to the following weight proportions: 100 parts epoxy resin, 3 parts nano diamond powder (40-80nm), 150 parts aluminum nitride, 10 parts diaminodiphenylmethane, and 0.5 parts silane coupling agent. After high-speed stirring and ball milling dispersion, a thermally conductive adhesive paste is prepared. It is then coated onto the release film using a coating machine. The solvent is dried and semi-cured in an oven to form a thermally conductive adhesive layer. (4) Soak the graphene sheets in a mixed solution of 98% concentrated sulfuric acid and 30% hydrogen peroxide in a volume ratio of 1:1 (the solid-liquid ratio of graphene sheets to the mixed solution is 1:5) and ball mill for 3 hours. After neutralizing with sodium hydroxide to neutral, filter and dry. Disperse the pretreated graphene sheets in a 15wt% polyamic acid solution (solid-liquid ratio of 1:5) and mix them by ultrasonication (20kHz) to form a uniform slurry. Place the slurry in a 5T strong magnetic field and coat it into a cast film. After the graphene in the film is highly oriented in the horizontal direction, perform a step-by-step heat treatment under an inert atmosphere. First, keep it at 110℃ for 10 hours, then keep it at 280℃ for 8 hours, then keep it at 800℃ for 10 hours, and finally treat it at 1500℃ for 1.5 hours and stretch it at 25MPa for 15 minutes to obtain the graphene composite sheet. (5) First, a thin layer of adhesive (thermal conductive paste prepared according to the above method) is coated on the aluminum substrate with an aluminum oxide film layer. Then, the graphene composite sheet layer 202, the thermally conductive adhesive layer 203, and the electroplated copper foil layer are stacked in sequence from bottom to top. Then, in a vacuum environment, a hot-pressing composite process is used for pressing. Specifically, in the first stage, the pressing is carried out at 80°C and 10MPa for 25 minutes; in the second stage, the pressing is carried out at 150°C and 15MPa for 80 minutes; in the third stage, the temperature is reduced to below 50°C, the pressure is released, and the composite board is taken out. From bottom to top, the layers are aluminum substrate layer 1, graphene composite high thermal conductivity layer 2, and electroplated copper foil layer 3. (6) A deep V-shaped groove is pre-cut on the side of the composite board. A precision laser source (ultraviolet laser, wavelength 355nm, power 20W, scanning speed 200mm / s) is used to scan and ablate the V-shaped groove from the side to obtain the desired graphene composite high thermal conductivity aluminum substrate. Its structural schematic diagram is shown below. Figure 1 As shown in the diagram, the structure of the graphene composite high thermal conductivity layer is as follows: Figure 2 As shown.

[0027] Example 2 A method for preparing a graphene-composite high thermal conductivity aluminum substrate includes the following steps: (1) Clean and degrease the aluminum substrate layer, and prepare the electroplated copper foil layer at the same time; (2) A mixed solution of 15% sulfuric acid, 1% oxalic acid, and 0.05% boric acid was used as the electrolyte, at a concentration of 1.5 A / dm³. 2Anodizing the aluminum substrate layer at 18℃ for 1 hour produces a porous anodic aluminum oxide film with a thickness of 40μm. Using chemical vapor deposition, the aluminum substrate layer with the porous anodic aluminum oxide film is placed in a CVD furnace, methane is introduced, and graphene is vertically grown in the pores of the porous anodic aluminum oxide film at 900℃ to obtain an aluminum oxide film layer on the aluminum substrate. (3) Mix the raw materials of the thermally conductive adhesive layer according to the following weight parts: 110 parts of epoxy resin, 5 parts of nano diamond powder (40-80nm), 180 parts of boron nitride, 15 parts of diaminodiphenylmethane, and 1 part of silane coupling agent. After high-speed stirring and ball milling dispersion, the thermally conductive adhesive paste is prepared. It is then coated onto the release film by a coating machine, and the solvent is dried and semi-cured in an oven to form a thermally conductive adhesive layer. (4) Soak the graphene sheets in a mixed solution of 98% concentrated sulfuric acid and 30% hydrogen peroxide in a volume ratio of 3:1 (the solid-liquid ratio of graphene sheets to the mixed solution is 1:7) and ball mill for 2.5 h. After neutralizing with sodium hydroxide to neutral, filter and dry. Disperse the pretreated graphene sheets in a 15wt% polyamic acid solution (solid-liquid ratio of 1:10) and mix them by ultrasonication (25kHz) to form a uniform slurry. Place the slurry in a 5T strong magnetic field and coat it into a cast film. After the graphene in the film is highly oriented in the horizontal direction, perform a step-by-step heat treatment under an inert atmosphere. First, keep it at 120℃ for 7 h, then keep it at 290℃ for 10 h, then keep it at 900℃ for 8 h, and finally treat it at 1800℃ for 2 h and then stretch it at 28MPa for 10 min to obtain the graphene composite sheet. (5) First, a thin layer of adhesive (thermal conductive paste prepared according to the above method) is coated on the aluminum substrate with an aluminum oxide film layer. Then, the graphene composite sheet, thermal conductive adhesive layer and copper foil layer are stacked in sequence from bottom to top. Then, the hot-pressing composite process is used in a vacuum environment for pressing. Specifically, in the first stage, the composite is pressed for 30 minutes at 90°C and 8MPa; in the second stage, the composite is pressed for 70 minutes at 160°C and 18MPa; in the third stage, the temperature is lowered to below 50°C, the pressure is released, and the composite board is taken out. (6) A V-shaped groove of a certain depth is pre-cut on the side of the composite board. A precision laser source (ultraviolet laser, wavelength of 355nm, power of 25W, scanning speed of 300mm / s) is used to scan and ablate the V-shaped groove from the side to obtain the desired graphene composite high thermal conductivity aluminum substrate.

[0028] Example 3 A method for preparing a graphene-composite high thermal conductivity aluminum substrate includes the following steps: (1) Clean and degrease the aluminum substrate layer, and prepare the electroplated copper foil layer at the same time; (2) A mixed solution of 15% sulfuric acid, 1% oxalic acid, and 0.05% boric acid was used as the electrolyte, at a concentration of 1.5 A / dm³. 2 Anodizing the aluminum substrate layer at 18℃ for 1 hour produces a porous anodic aluminum oxide film with a thickness of 50μm. Using chemical vapor deposition, the aluminum substrate layer with the porous anodic aluminum oxide film is placed in a CVD furnace, methane is introduced, and graphene is vertically grown in the pores of the porous anodic aluminum oxide film at 900℃ to obtain an aluminum oxide film layer on the aluminum substrate. (3) Mix the raw materials of the thermally conductive adhesive layer according to the following weight proportions: 120 parts epoxy resin, 10 parts nano diamond powder (40-80nm), 200 parts aluminum nitride, 20 parts diaminodiphenylmethane, and 1.5 parts silane coupling agent. After high-speed stirring and ball milling dispersion, a thermally conductive adhesive paste is prepared. It is then coated onto the release film using a coating machine. The solvent is dried and semi-cured in an oven to form a thermally conductive adhesive layer. (4) Soak the graphene sheets in a mixed solution of 98% concentrated sulfuric acid and 30% hydrogen peroxide at a volume ratio of 5:1 (the solid-liquid ratio of graphene sheets to the mixed solution is 1:10) and ball mill for 2 hours. After neutralizing with sodium hydroxide to neutral, filter and dry. Disperse the pretreated graphene sheets in a 15wt% polyamic acid solution (solid-liquid ratio of 1:15) and mix them by ultrasonication (35kHz) to form a uniform slurry. Place the slurry in a 5T strong magnetic field and coat it into a cast film. After the graphene in the film is highly oriented in the horizontal direction, perform a step-by-step heat treatment under an inert atmosphere. First, keep it at 130℃ for 5 hours, then at 300℃ for 5 hours, then at 1000℃ for 5 hours, and finally at 2000℃ for 1 hour. Then, stretch it at 30MPa for 2 minutes to obtain the graphene composite sheet. (5) First, a thin layer of adhesive (thermal conductive paste prepared according to the above method) is coated on the aluminum substrate with an aluminum oxide film layer. Then, the graphene composite sheet, thermal conductive adhesive layer and copper foil layer are stacked in sequence from bottom to top. Then, the hot-pressing composite process is used in a vacuum environment for pressing. Specifically, in the first stage, the composite is pressed for 20 minutes at 100°C and 5MPa; in the second stage, the composite is pressed for 60 minutes at 180°C and 20MPa; in the third stage, the temperature is lowered to below 50°C, the pressure is released, and the composite board is taken out. (6) A V-shaped groove of a certain depth is pre-cut on the side of the composite board. A precision laser source (ultraviolet laser, wavelength of 355nm, power of 30W, scanning speed of 500mm / s) is used to scan and ablate the V-shaped groove from the side to obtain the desired graphene composite high thermal conductivity aluminum substrate.

[0029] Comparative Example 1 A method for preparing a graphene-composite high thermal conductivity aluminum substrate differs from Example 1 in that... Step (2) is as follows: A mixed solution of 15% sulfuric acid, 1% oxalic acid, and 0.05% boric acid (by mass) is used as the electrolyte, and the electrolyte is applied at 1.5 A / dm³. 2 Anodizing of the aluminum substrate layer at 18℃ for 1 hour produces a porous anodic aluminum oxide film with a thickness of 30μm.

[0030] Comparative Example 2 A method for preparing a graphene-composite high thermal conductivity aluminum substrate differs from Example 1 in that... Step (4) is as follows: Soak graphene sheets in a mixed solution of 98% concentrated sulfuric acid and 30% hydrogen peroxide in a volume ratio of 1:1 (solid-liquid ratio of graphene sheets to mixed solution is 1:5) and ball mill for 3 hours. After neutralizing with sodium hydroxide to neutrality, filter and dry. Disperse the pretreated graphene sheets in a 15wt% polyamic acid solution (solid-liquid ratio is 1:5) and mix with ultrasound (20kHz) to form a uniform slurry. Perform step heat treatment on the slurry directly under an inert atmosphere. First, keep it at 110℃ for 10 hours, then keep it at 280℃ for 8 hours, then keep it at 800℃ for 10 hours, and finally treat it at 1500℃ for 1.5 hours and press it at 25MPa for 15 minutes to obtain the graphene composite sheet.

[0031] Comparative Example 3 A method for preparing a graphene-composite high thermal conductivity aluminum substrate differs from Example 1 in that... In step (3), the raw materials of the thermally conductive adhesive layer are mixed according to the following weight proportions: 100 parts epoxy resin, 150 parts aluminum nitride, 10 parts diaminodiphenylmethane, and 0.5 parts silane coupling agent. After high-speed stirring and ball milling dispersion, a thermally conductive adhesive paste is prepared. It is then coated onto the release film using a coating machine, and the solvent is dried and semi-cured in an oven to form a thermally conductive adhesive layer.

[0032] Comparative Example 4 A method for preparing a graphene-composite high thermal conductivity aluminum substrate differs from Example 1 in that... No step (2) processing steps.

[0033] Comparative Example 5 A method for preparing a graphene-composite high thermal conductivity aluminum substrate includes the following steps: (1) Clean and degrease the aluminum substrate layer, and prepare the electroplated copper foil layer at the same time; (2) Mix the raw materials of graphene composite high thermal conductivity layer according to the following weight parts: 100 parts epoxy resin, 10 parts graphene, 3 parts nano diamond powder (40-80nm), 150 parts aluminum nitride, 10 parts diaminodiphenylmethane, and 0.5 parts silane coupling agent. After high-speed stirring and ball milling dispersion, a thermally conductive paste is prepared. It is coated onto the release film by a coating machine, and the solvent is dried and semi-cured in an oven to form a graphene composite high thermal conductivity layer. (3) First, a thin layer of adhesive (organic silicone thermal conductive adhesive) is coated on the aluminum substrate layer, and then the graphene composite high thermal conductivity layer and the copper foil layer are stacked in sequence from bottom to top. Then, in a vacuum environment, a hot-pressing composite process is used for pressing. Specifically: in the first stage, the composite is pressed for 25 minutes at 80°C and 10MPa; in the second stage, the composite is pressed for 80 minutes at 150°C and 15MPa; in the third stage, the temperature is lowered to below 50°C, the pressure is released, and the composite board is taken out. (4) A V-shaped groove of a certain depth is pre-cut on the side of the composite plate. A precision laser source (ultraviolet laser, wavelength of 355nm, power of 20W, scanning speed of 200mm / s) is used to scan and erode the V-shaped groove from the side to obtain the desired graphene composite high thermal conductivity aluminum substrate.

[0034] Comparative Example 6 A method for preparing a graphene-composite high thermal conductivity aluminum substrate differs from Example 1 in that... In step (6), the shape is processed using ordinary CNC die stamping process.

[0035] The thermal conductivity, coefficient of thermal expansion, bending strength, and warping of the aluminum substrates prepared in Examples 1-3 and Comparative Examples 1-6 were tested, and the results are shown in Table 1. The thermal conductivity was tested according to ASTM D5470, the coefficient of thermal expansion according to ASTM E831, the bending strength according to ASTM D790, and the warping was tested using the IPC-TR-591 method.

[0036] Table 1 Performance Test Results

[0037] As can be seen from the results in Table 1, the aluminum substrate prepared by the method of the present invention has high thermal conductivity, low coefficient of thermal expansion, good bending strength, extremely low warping, and excellent overall performance. In contrast, Comparative Example 1, where the lower layer of the graphene composite high thermal conductivity layer lacked graphene modification, resulted in a significant reduction in thermal conductivity. Similarly, in Comparative Example 2, the middle layer of the graphene composite high thermal conductivity layer lacked horizontal orientation treatment, severely impacting all its properties. In Comparative Example 3, the upper layer of the graphene composite high thermal conductivity layer lacked nanodiamond powder, leading to poor longitudinal thermal conductivity and a decreased thermal conductivity coefficient, similarly affecting other properties. In Comparative Example 4, the absence of a lower layer in the graphene composite high thermal conductivity layer resulted in a decline in overall performance. In Comparative Example 5, the graphene composite high thermal conductivity layer was not oriented but directly mixed, significantly reducing its thermal conductivity and causing a large coefficient of thermal expansion and severe warping. Comparative Example 6 used ordinary CNC die-stamping for shaping, which, while having little impact on thermal conductivity, thermal expansion, and strength, failed to offset residual stress, resulting in severe warping problems. These results further demonstrate the superiority and feasibility of the preparation method of this invention.

[0038] In addition, the present invention uses a side-entry laser processing system for shape processing, which has higher precision and improves utilization rate by more than 30% compared with ordinary CNC die stamping process.

[0039] Finally, it should be emphasized that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention can have various changes and modifications. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A graphene composite high thermal conductive aluminum substrate, characterized in that, The graphene composite high-thermal-conductivity aluminum substrate comprises a conductive copper foil layer, a graphene composite high-thermal-conductivity layer, and an aluminum substrate layer; the graphene composite high-thermal-conductivity layer comprises an upper layer, a middle layer, and a lower layer; the upper layer is connected with the conductive copper foil layer and is a thermal-conductivity adhesive layer; the middle layer is a graphene composite sheet layer and is a film layer obtained by hot pressing of graphene and a polymer; and the lower layer is connected with the aluminum substrate layer and is an aluminum oxide film layer modified by graphene. The graphene in the graphene composite sheet layer is horizontally oriented. The graphene in the aluminum oxide film layer is vertically oriented.

2. The graphene composite high thermal conductive aluminum substrate according to claim 1, characterized in that, The preparation method of the graphene composite sheet layer comprises the following steps: soaking graphene sheets in a concentrated sulfuric acid and hydrogen peroxide mixed solution and ball milling for 2-3 hours, neutralizing the graphene sheets with sodium hydroxide to neutral, filtering, and drying; dispersing the pretreated graphene sheets in a polyamide acid solution, ultrasonic mixing to obtain a uniform slurry; placing the slurry in a strong magnetic field and coating the slurry to form a film by doctor blading; after the graphene in the film is horizontally oriented, performing stepwise heat treatment in an inert atmosphere, and then performing extension pressing at 25-30 MPa for 2-15 minutes to obtain the graphene composite sheet layer.

3. The graphene composite high thermal conductive aluminum substrate according to claim 2, characterized in that, The graphene sheets are large-diameter graphene oxide; the concentrated sulfuric acid and hydrogen peroxide mixed solution is a mixed solution of 98% concentrated sulfuric acid and 30% hydrogen peroxide with a volume ratio of 1-5:1; the solid-liquid ratio of the graphene sheets to the concentrated sulfuric acid and hydrogen peroxide mixed solution is 1:5-10; the solid-liquid ratio of the graphene sheets to the polyamide acid solution is 1:5-20; and the ultrasonic frequency is 20-35 kHz.

4. The graphene composite high thermal conductive aluminum substrate according to claim 2, wherein, The stepwise heat treatment process comprises the following steps: first, heat treatment at 110-130℃ for 5-10 hours, then heat treatment at 280-300℃ for 5-10 hours, then heat treatment at 800-1000℃ for 5-10 hours, and finally heat treatment at 1500-2000℃ for 1-2 hours.

5. The graphene composite high thermal conductive aluminum substrate according to claim 1, wherein, The raw materials of the thermal-conductivity adhesive layer comprise, by weight, 100-120 parts of epoxy resin, 3-10 parts of nano-diamond powder, 150-200 parts of aluminum nitride or boron nitride, 10-20 parts of a curing agent, and 0.5-1.5 parts of a coupling agent; the particle size of the nano-diamond powder is 40-80 nm; the curing agent is diamino diphenyl methane; and the coupling agent is a silane coupling agent.

6. A method for preparing a graphene composite high thermal conductivity aluminum substrate according to any one of claims 1-5, characterized in that, The method comprises the following steps: (1) cleaning and degreasing the aluminum substrate layer; (2) generating a porous anodic aluminum oxide film on the surface of the aluminum substrate by an electrochemical anodic oxidation process, and vertically growing graphene on the porous anodic aluminum oxide film by a chemical vapor deposition process to obtain the aluminum oxide film layer on the aluminum substrate; (3) mixing the raw materials of the thermal-conductivity adhesive layer according to the proportions, high-speed stirring, ball milling, and dispersion to obtain a thermal-conductivity adhesive paste, coating the paste on a release film by a coating machine, drying the solvent and semi-curing the paste in an oven, and forming the thermal-conductivity adhesive layer; (4) preparing the graphene composite sheet layer and the conductive copper foil layer; (5) coating a thin layer of adhesive on the aluminum substrate with the aluminum oxide film layer, stacking the graphene composite sheet layer, the thermal-conductivity adhesive layer, and the conductive copper foil layer in sequence from bottom to top, and then pressing the layers by a hot pressing process to obtain a composite board. (6) The composite board is processed by a side-in laser processing system to obtain a graphene composite high-thermal-conductivity aluminum substrate.

7. The method of claim 6, wherein the graphene composite high thermal conductive aluminum substrate is prepared by the following steps: coating a graphene layer on a surface of an aluminum substrate; and coating a silver layer on the graphene layer. In step (2), the electrochemical anodic oxidation process is as follows: using a mixed solution of 15% sulfuric acid, 1% oxalic acid and 0.05% boric acid as electrolyte, anodizing the aluminum substrate layer at 1.5 A / dm 2 at 18°C for 1 h to form a porous anodic aluminum oxide film with a thickness of 30-50 μm; the chemical vapor deposition process is as follows: placing the aluminum substrate layer with the porous anodic aluminum oxide film into a CVD furnace, introducing methane, and growing graphene in the pores of the porous anodic aluminum oxide film at 900°C.

8. The method of claim 6, wherein the graphene composite high thermal conductive aluminum substrate is prepared by the steps of: preparing a graphene solution; mixing the graphene solution with an aluminum powder; and sintering the mixture to obtain the graphene composite high thermal conductive aluminum substrate. In step (4), the hot-pressing composite process is divided into three stages and is performed in a vacuum environment, specifically: in the first stage, the composite board is pressed for 20-30 min at 80-100 ℃ and a pressure of 5-10 MPa; in the second stage, the composite board is pressed for 60-80 min at 150-180 ℃ and a pressure of 15-20 MPa; and in the third stage, the composite board is cooled to below 50 ℃, the pressure is released, and the composite board is taken out.

9. The method of claim 6, wherein the graphene composite high thermal conductive aluminum substrate is prepared by the steps of: preparing a graphene solution; mixing the graphene solution with an aluminum powder; and sintering the mixture to obtain the graphene composite high thermal conductive aluminum substrate. In step (5), the side-in laser processing is performed by pre-opening a V-shaped groove with a certain depth on the side of the composite board, and using a precise laser source to scan and ablate the V-shaped groove from the side to obtain the required aluminum substrate; the laser source is an ultraviolet laser with a wavelength of 355 nm and a power of 20-30 W, and the scanning speed is 200-500 mm / s.

10. Use of the graphene composite high-thermal-conductivity aluminum substrate according to any one of claims 1-6 or prepared by the method according to any one of claims 7-9 in electronic devices and circuit boards.

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