Graphite aluminum-metal composite heat-conducting sheet and preparation method thereof

Abstract

The application discloses a graphite-aluminum-metal composite heat-conducting sheet and a preparation method thereof, and belongs to the technical field of layered heat-dissipating materials. The graphite-aluminum-metal composite heat-conducting sheet disclosed by the application comprises at least one group of first composite heat-conducting layers and second composite heat-conducting layers which are arranged in a laminated mode; at least one of the first composite heat-conducting layers and the second composite heat-conducting layers is arranged as a metal reinforced composite layer, the metal reinforced composite layer is composed of a graphite-aluminum composite heat-conducting material layer and metal embedded in the graphite-aluminum composite heat-conducting material layer; wherein the positions of the metal embedded in the first composite heat-conducting layer and the second composite heat-conducting layer of each group are not overlapped, thereby forming local metal regions with different metal embedding positions; and the application effectively solves the technical problem that the graphite-aluminum composite heat-conducting material cannot be attached to a device.

Description

Technical Field

[0001] This invention belongs to the field of layered heat dissipation materials technology, specifically relating to a graphite aluminum-metal composite heat-conducting sheet and its preparation method. Background Technology

[0002] With the rapid development of new energy vehicles, 5G technology, and high-performance computing devices, the demand for high-power electronic devices is increasing daily. These devices generate a large amount of heat during operation, causing their temperatures to rise sharply. Excessive operating temperatures can severely impact the performance and lifespan of electronic devices; therefore, efficient heat dissipation has become a critical factor in ensuring stable system operation. Against this backdrop, graphite-aluminum composite materials with high in-plane thermal conductivity have gradually attracted attention and are considered a potential alternative to traditional heat dissipation materials such as copper and aluminum. Their unique thermal conductivity makes them particularly suitable for critical components such as heat sinks for power devices and thermal management modules.

[0003] Although graphite-aluminum composites possess excellent thermal conductivity in certain directions, their poor mechanical properties make them difficult to install using conventional mechanical fastening methods such as threaded connections, limiting their application in practical structures. Furthermore, the generally high surface roughness of these materials results in numerous micro-gaps at the interface when directly bonded to high-power devices, creating additional contact thermal resistance and hindering effective heat conduction. This means that the material's inherent high thermal conductivity cannot be fully utilized in practical applications, impacting overall heat dissipation performance.

[0004] To address the aforementioned issues, existing technologies typically employ welding graphite-aluminum composite materials to metals. Specifically, this involves completely encapsulating the graphite-aluminum composite material with a metal material such as aluminum alloy, or covering its entire surface. The smooth surface of the metal layer allows for a tight bond with the power device, thereby reducing interfacial thermal resistance. This approach improves interfacial contact conditions to some extent and enhances the mechanical support properties of the composite material, making it suitable for a wider range of structural applications.

[0005] However, while the monolithic metal cladding improves interface quality and structural strength, it also introduces new problems. The introduction of the metal layer adds an extra thermal conductivity interface and material thermal resistance, leading to an increase in the overall heat dissipation path's thermal resistance and thus reducing heat transfer efficiency. Furthermore, this process involves multiple steps, including metal forming, welding, and surface treatment, making it complex and costly, which is detrimental to large-scale production and market promotion. Therefore, how to minimize the impact on thermal conductivity and simplify the manufacturing process while ensuring interface quality and structural strength has become a key issue that needs to be addressed. Summary of the Invention

[0006] The purpose of this invention is to provide a graphite-aluminum-metal composite thermal conductive sheet and its preparation method, in order to solve the technical problem that the high surface roughness of existing graphite-aluminum composite materials leads to large contact thermal resistance with devices, making it impossible to directly attach them to devices.

[0007] To achieve the above objectives, the present invention employs the following technical solution:

[0008] This invention discloses a graphite aluminum-metal composite thermal conductive sheet, comprising at least one set of stacked first composite thermal conductive layer and second composite thermal conductive layer;

[0009] At least one of the first composite thermal conductive layer and the second composite thermal conductive layer is configured as a metal-reinforced composite layer, wherein the metal-reinforced composite layer is composed of a graphite-aluminum composite thermal conductive material layer and a metal embedded in the graphite-aluminum composite thermal conductive material layer;

[0010] When both the first composite thermal conductive layer and the second composite thermal conductive layer are configured as metal-reinforced composite layers, the positions of the metals embedded in the first composite thermal conductive layer and the second composite thermal conductive layer in each group do not overlap, forming local metal regions with different metal embedding positions.

[0011] Furthermore, when one of the first composite thermal conductive layer and the second composite thermal conductive layer is set as a metal-reinforced composite layer, the other is set as a graphite-aluminum composite thermal conductive material layer;

[0012] When both the first composite thermal conductive layer and the second composite thermal conductive layer are set as metal-reinforced composite layers, the metal embedding positions in the first composite thermal conductive layer are different from those in the second composite thermal conductive layer.

[0013] Furthermore, the sides of the metal-reinforced composite layer are also covered with a metal layer.

[0014] Furthermore, in the metal-reinforced composite layer, the metal is an aluminum alloy or pure aluminum; the shape of the metal embedded in the graphite-aluminum composite thermally conductive material layer is a polygonal block or a circular block.

[0015] Furthermore, the thickness of the graphite aluminum-metal composite thermal conductive sheet is not less than 0.5 mm.

[0016] Furthermore, the first composite thermal conductive layer and the second composite thermal conductive layer are stacked together through metallurgical bonding.

[0017] This invention also discloses a method for preparing the above-mentioned graphite-aluminum-metal composite thermal conductive sheet, comprising the following steps:

[0018] S1: Based on the bonding position of the heating element, at least one of the first composite thermal conductive layer and the second composite thermal conductive layer is set as a metal-reinforced composite layer, and the embedding position of the metal in the selected first composite thermal conductive layer and / or second composite thermal conductive layer is determined. When both the first composite thermal conductive layer and the second composite thermal conductive layer are set as metal-reinforced composite layers, local metal areas with different metal embedding positions are formed.

[0019] S2: At least one set of first composite thermal conductive layer and second composite thermal conductive layer set in S1 are sequentially and alternately placed into the mold and sintered to obtain a graphite aluminum-metal composite material block with alternating layered structure.

[0020] S3: The graphite aluminum-metal composite material block with alternating layered structure is cut laterally to obtain a graphite aluminum-metal composite heat-conducting sheet.

[0021] Furthermore, in S2, before sintering, an aluminum solder sheet is laid between the first composite thermal conductive layer and the second composite thermal conductive layer.

[0022] Furthermore, the sintering process is carried out in a vacuum hot press furnace.

[0023] Furthermore, the sintering temperature is 670~710℃, the holding time is 0.5~1.5 h, and the pressure during sintering is 5~20 MPa.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] This invention discloses a graphite-aluminum-metal composite thermal conductive sheet. By embedding metals at different positions in the first and second composite thermal conductive layers, local metal regions are formed. The smooth surface of the metal regions can significantly reduce roughness while minimizing the loss of thermal conductivity, effectively solving the technical problem that graphite-aluminum composite thermal conductive materials cannot be directly attached to devices.

[0026] Furthermore, the sides of the metal-reinforced composite layer are also covered with a metal layer, which can utilize the strength of the metal to improve the overall structural strength of the product, while also enabling mechanical connections.

[0027] Furthermore, the metal is embedded in the graphite-aluminum composite thermal conductive material layer in polygonal or circular blocks, which can be adapted to devices of different shapes.

[0028] Furthermore, the thickness of the graphite aluminum-metal composite heat-conducting sheet is not less than 0.5 mm, which ensures that it has a certain structural strength.

[0029] Furthermore, the first composite thermal conductive layer and the second composite thermal conductive layer are combined in a metallurgical manner. This combination method has no contact thermal resistance, and the device can generate heat through rapid heat transfer to the graphite-aluminum composite thermal conductive material layer connected to it. The high in-plane thermal conductivity of the graphite-aluminum composite thermal conductive material layer is used to achieve temperature uniformity.

[0030] The present invention also discloses a method for preparing the above-mentioned graphite aluminum-metal composite thermal conductive sheet. This method can be achieved by simply using a sintering process, and has the advantages of simple process and mass production capability. Attached Figure Description

[0031] Figure 1 This is a schematic diagram of the graphite-aluminum-metal composite heat-conducting sheet in Embodiment 1 of the present invention;

[0032] Figure 2 for Figure 1 Side view of the first composite thermal conductive layer after being cut along the AA section line;

[0033] Figure 3 for Figure 2 A detailed image of section B, enlarged at a 4:1 scale;

[0034] Figure 4 for Figure 2 A detailed image of section C, magnified at a 4:1 scale;

[0035] Figure 5 This is a schematic diagram of the graphite-aluminum-metal composite heat-conducting sheet in Embodiment 2 of the present invention;

[0036] Figure 6 for Figure 5 Side view of the first composite thermal conductive layer after being cut along the AA section line;

[0037] Figure 7 for Figure 6 A detailed image of section B, enlarged at a 4:1 scale;

[0038] Figure 8 for Figure 6 A detailed image of section C, magnified at a 4:1 scale;

[0039] Figure 9 This is a schematic diagram of the graphite-aluminum-metal composite heat-conducting sheet in Embodiment 3 of the present invention;

[0040] Figure 10 for Figure 9 Side view of the first composite thermal conductive layer after being cut along the AA section line;

[0041] Wherein: 1, first composite thermal conductive layer; 2, second composite thermal conductive layer; a, graphite-aluminum composite thermal conductive material layer; b, metal; AA, cutting line; A1, the position of the metal embedded in the graphite-aluminum composite thermal conductive material layer in the first composite thermal conductive layer of Example 1; A2, the position of the metal embedded in the graphite-aluminum composite thermal conductive material layer in the second composite thermal conductive layer of Example 1. Detailed Implementation

[0042] To enable those skilled in the art to understand the features and effects of the present invention, the terms and expressions used herein are explained and defined in general terms below. Unless otherwise specified, all technical and scientific terms used herein have the common meaning understood by those skilled in the art regarding the present invention, and in case of conflict, the definitions in this specification shall prevail.

[0043] The theories or mechanisms described and disclosed herein, whether right or wrong, should not in any way limit the scope of the invention, that is, the contents of the invention can be implemented without being limited by any particular theory or mechanism.

[0044] In this document, all features defined by numerical ranges or percentage ranges, such as numerical values, quantities, contents, and concentrations, are for the sake of brevity and convenience only. Accordingly, descriptions of numerical ranges or percentage ranges should be considered as covering and specifically disclosing all possible sub-ranges and individual numerical values ​​(including integers and fractions) within those ranges.

[0045] In this article, unless otherwise specified, “contains,” “includes,” “containing,” “has,” or similar terms cover the meanings of “composed of” and “mainly composed of,” for example, “A contains a” covers the meanings of “A contains a and others” and “A contains only a.”

[0046] For the sake of brevity, not all possible combinations of the technical features in each implementation scheme or embodiment are described herein. Therefore, as long as there is no contradiction in the combination of these technical features, the technical features in each implementation scheme or embodiment can be combined arbitrarily, and all possible combinations should be considered within the scope of this specification.

[0047] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims.

[0048] The graphite-aluminum-metal composite thermal conductive sheet disclosed in this invention includes at least one set of first composite thermal conductive layer 1 and second composite thermal conductive layer 2 stacked together; when there are several sets, the several sets of first composite thermal conductive layer 1 and second composite thermal conductive layer 2 are stacked in the vertical direction.

[0049] At least one of the first composite thermal conductive layer 1 and the second composite thermal conductive layer 2 is configured as a metal-reinforced composite layer, wherein the metal-reinforced composite layer is composed of a graphite-aluminum composite thermal conductive material layer and a metal embedded in the graphite-aluminum composite thermal conductive material layer;

[0050] In this case, the positions of the metals embedded in the first composite thermal conductive layer 1 and the second composite thermal conductive layer 2 in each group do not overlap, forming local metal areas with different metal embedding positions.

[0051] Example 1

[0052] This embodiment provides a method for preparing a graphite aluminum-metal composite thermal conductive sheet, including the following steps:

[0053] Step 1: Prepare several 4011 aluminum alloy plates, each 20mm long, 20mm wide, and 2mm thick, and clean and dry them;

[0054] Step 2: Prepare several pieces of graphite-aluminum composite thermal conductive material, each 200mm long, 150mm wide, and 2mm thick, and laser-cut them to create through holes 20mm long and 20mm wide. The positions of the through holes are divided into two types according to the different heat source distribution positions on the two sides: the first type has four through holes distributed at the four corners, each 20mm away from the two adjacent perpendicular edges; the second type has two through holes spaced 40mm apart, arranged along the long side of the material, and located at the center of the material. Prepare several layers of graphite-aluminum composite thermal conductive material a with two different through holes, clean and dry them.

[0055] Step 3: Embed the 4011 aluminum alloy plate from Step 1 into the through holes of the two different graphite-aluminum composite thermal conductive material layers a from Step 2 to obtain the first composite thermal conductive layer 1 and the second composite thermal conductive layer 2.

[0056] Step 4: The first composite thermal conductive layer 1 and the second composite thermal conductive layer 2 are alternately stacked in a special casting mold, and then sintered in a vacuum hot press furnace. The sintering temperature is 700 ℃, the holding time is 50 min, and the pressure during the sintering process is 10 MPa, to obtain a graphite aluminum-metal composite material block with an alternating layered structure.

[0057] Step 5: The graphite aluminum-metal composite material block with alternating layered structure obtained in Step 4 is transversely cut by multi-wire cutting to obtain a 2 mm thick graphite aluminum-metal composite heat-conducting sheet with two different sides.

[0058] According to relevant experimental results, the surface roughness of the graphite-aluminum composite thermal conductive material layer a in the graphite-aluminum composite thermal conductive sheet prepared in this embodiment is 1.73 μm, and the surface roughness of the metal portion embedded in the graphite-aluminum composite thermal conductive material layer a is 0.63 μm; the equivalent thermal conductivity of the graphite-aluminum composite thermal conductive sheet is approximately 520 W / (m·K).

[0059] Example 2

[0060] This embodiment provides a method for preparing a graphite aluminum-metal composite thermal conductive sheet, including the following steps:

[0061] Step 1: Prepare several 6063 aluminum alloy plates with a length of 200mm, a width of 150mm, and a thickness of 1mm, and laser cut them to make a through hole with a length of 190mm and a width of 140mm in the center of the 6063 aluminum alloy plate, so as to obtain an aluminum plate with a through hole. Then clean and dry it.

[0062] Step 2: Prepare several 6063 aluminum alloy plates, each 100mm long, 20mm wide, and 1mm thick, and clean and dry them;

[0063] Step 3: Prepare several pieces of graphite-aluminum composite thermal conductive material with a length of 190mm, a width of 140mm, and a thickness of 1mm. Laser cut one half of them and cut a through hole with a length of 100mm and a width of 20mm at the center. The long side of the through hole is parallel to the short side of the material to obtain graphite-aluminum composite thermal conductive material with through hole. Clean and dry it to obtain two different graphite-aluminum composite thermal conductive material layers a.

[0064] Step 4: Provide several 4047 aluminum welding sheets, each 200mm long, 150mm wide, and 0.07mm thick;

[0065] Step 5: Alternately stack the perforated aluminum plates obtained in Step 1 in a special casting mold, and alternately stack the two different graphite-aluminum composite thermal conductive materials from Step 3 in the center of the perforated aluminum plates. Embed the aluminum plates from Step 2 into the perforated holes of the two different graphite-aluminum composite thermal conductive material layers a to obtain several first composite thermal conductive layers 1 and second composite thermal conductive layers 2. Then, place the 4047 aluminum welding sheet from Step 3 between the stacked first composite thermal conductive layers 1 and second composite thermal conductive layers 2, and then sinter it in a vacuum hot press furnace. The sintering temperature is 680℃, the holding time is 60min, and the pressure during sintering is 5 MPa to obtain a graphite-aluminum-metal composite material block with an alternating layered structure.

[0066] Step 6: The graphite aluminum-metal composite material block with alternating layered structure is transversely cut by multi-wire cutting to obtain a 1mm thick graphite aluminum-metal composite heat-conducting sheet with two different sides.

[0067] According to relevant experimental results, the surface roughness of the graphite-aluminum composite thermal conductive material layer a in the graphite-aluminum composite thermal conductive sheet is 1.76 μm, and the surface roughness of the metal part embedded in the graphite-aluminum composite thermal conductive material layer a is 0.58 μm; the equivalent thermal conductivity of the graphite-aluminum composite thermal conductive sheet is approximately 504 W / (m·K).

[0068] Example 3

[0069] This embodiment provides a method for preparing a graphite aluminum-metal composite thermal conductive sheet, including the following steps:

[0070] Step 1: Provide several 1100 pure aluminum plates with a length of 150mm, a width of 150mm, and a thickness of 3mm, and laser cut them to make a "+" shaped through hole formed by two rectangles with a length of 140mm and a width of 100mm rotated 90° from the center, so as to obtain an aluminum plate with a "+" shaped hole.

[0071] Step 2: Provide several 1100 pure aluminum plates with a diameter of 20mm and a thickness of 3mm;

[0072] Step 3: Provide several 3mm thick graphite-aluminum composite thermal conductive materials and laser cut them to cut out a "+" shaped graphite-aluminum composite thermal conductive material block in the center, which is composed of two rectangles with a length of 140mm and a width of 100mm rotated 90° from the center. Then, cut out a 20mm diameter circular through hole in the center of the "+" shape by laser cutting in one half, to obtain several graphite-aluminum composite thermal conductive material layers with circular holes and graphite-aluminum composite thermal conductive material layers without circular holes, that is, two different graphite-aluminum composite thermal conductive material layers a;

[0073] Step 4: The aluminum plates with "+" shaped holes obtained in Step 1 are stacked in a special casting mold. The graphite-aluminum composite thermal conductive material layer with round holes and the graphite-aluminum composite thermal conductive material layer without round holes from Step 3 are alternately stacked in the corresponding "+" shaped through holes. Then, the pure aluminum plate from Step 2 is embedded in the through holes of the graphite-aluminum composite thermal conductive material layer with round holes to obtain the first composite thermal conductive layer 1 and the second composite thermal conductive layer 2. Then, sintering is carried out in a vacuum hot press furnace at a temperature of 703 ℃, a holding time of 40 min, and a pressure of 20 MPa to obtain a graphite-aluminum-metal composite material block with an alternating layered structure.

[0074] Step 5: The graphite aluminum-metal composite material block obtained in Step 4 is transversely cut by multi-wire cutting to obtain a 3mm thick graphite aluminum-metal composite heat-conducting sheet with two different sides.

[0075] According to relevant experimental results, the surface roughness of the graphite-aluminum composite thermal conductive material layer in the graphite-aluminum composite thermal conductive sheet is 1.82 μm, and the surface roughness of the metal portion embedded in the graphite-aluminum composite thermal conductive material layer is 0.65 μm; the equivalent thermal conductivity of the graphite-aluminum composite thermal conductive sheet is approximately 466 W / (m·K).

[0076] Figure 1 This is a schematic diagram of the graphite-aluminum-metal composite heat-conducting sheet in Embodiment 1 of the present invention. Figure 2 , Figure 3 and Figure 4 The diagrams show a side view and detailed views. It can be seen from these diagrams that the embedding positions of metal b in the first composite thermal conductive layer 1 and the second composite thermal conductive layer 2 of the graphite-aluminum-metal composite thermal conductive sheet are different. Specifically, in the first composite thermal conductive layer 1, the position of metal b embedded in the graphite-aluminum composite thermal conductive material layer is denoted as A1, while in the second composite thermal conductive layer 2, the position of metal b embedded in the graphite-aluminum composite thermal conductive material layer is denoted as A2. Positions A1 and A2 do not overlap. This graphite-aluminum-metal composite thermal conductive sheet only arranges metal b (4011 aluminum alloy plate) at the heat source distribution area, maximizing the utilization of the high thermal conductivity of the graphite-aluminum composite thermal conductive material.

[0077] Figure 5 This is a schematic diagram of the graphite-aluminum-metal composite heat-conducting sheet in Embodiment 2 of the present invention. Figure 6 , Figure 7 and Figure 8 The images show a side view and detailed views. As can be seen from the images, in addition to the metal b (6063 aluminum alloy plate) placed at the heat source distribution point, the graphite aluminum-metal composite heat-conducting sheet also has a metal frame of 6063 aluminum alloy plate, which enhances the structural strength of the product.

[0078] Figure 9 This is a schematic diagram of the graphite-aluminum-metal composite heat-conducting sheet in Embodiment 3 of the present invention. Figure 10 The diagram above shows the side view of the structure. As can be seen from the diagram, metal b (1100 pure aluminum plate) is arranged at the four corners of the graphite aluminum-metal composite heat-conducting sheet, which can be connected to the structure such as threaded holes and fins.

[0079] The above content is only for illustrating the technical concept of the present invention and should not be construed as limiting the scope of protection of the present invention. Any modifications made to the technical solution based on the technical concept proposed in this invention shall fall within the scope of protection of the claims of this invention.

Claims

1. A graphite-aluminum-metal composite thermal conductive sheet, characterized in that, It includes at least one set of stacked first composite thermal conductive layer (1) and second composite thermal conductive layer (2); The first composite thermal conductive layer (1) and the second composite thermal conductive layer (2) are both set as metal-reinforced composite layers. The metal-reinforced composite layer is composed of a graphite-aluminum composite thermal conductive material layer and metal embedded in the graphite-aluminum composite thermal conductive material layer. The positions of the metals embedded in the first composite thermal conductive layer (1) and the second composite thermal conductive layer (2) in each group do not overlap, forming local metal areas with different metal embedding positions.

2. The graphite-aluminum-metal composite thermal conductive sheet according to claim 1, characterized in that, The sides of the metal-reinforced composite layer are also covered with a metal layer.

3. The graphite-aluminum-metal composite thermal conductive sheet according to claim 1, characterized in that, In the metal-reinforced composite layer, the metal is an aluminum alloy or pure aluminum; the shape of the metal embedded in the graphite-aluminum composite thermally conductive material layer is a polygonal block or a circular block.

4. A graphite-aluminum-metal composite thermal conductive sheet according to claim 1, characterized in that, The thickness of the graphite aluminum-metal composite heat-conducting sheet is not less than 0.5 mm.

5. The graphite-aluminum-metal composite thermal conductive sheet according to claim 1, characterized in that, The first composite thermal conductive layer (1) and the second composite thermal conductive layer (2) are stacked by metallurgical bonding.

6. A method for preparing a graphite-aluminum-metal composite thermal conductive sheet according to any one of claims 1 to 5, characterized in that, Includes the following steps: S1: Based on the pasting position of the heating element, both the first composite heat-conducting layer (1) and the second composite heat-conducting layer (2) are set as metal-reinforced composite layers, and the embedding position of the metal in the selected first composite heat-conducting layer (1) and / or the second composite heat-conducting layer (2) is determined to form local metal areas with different metal embedding positions. S2: At least one set of first composite thermal conductive layer (1) and second composite thermal conductive layer (2) set by S1 are sequentially and alternately placed into the mold and sintered to obtain a graphite aluminum-metal composite material block with alternating layered structure. S3: The graphite aluminum-metal composite material block with alternating layered structure is cut laterally to obtain a graphite aluminum-metal composite heat-conducting sheet.

7. The method for preparing a graphite-aluminum-metal composite thermal conductive sheet according to claim 6, characterized in that, In S2, before sintering, aluminum solder sheets are laid between the first composite thermal conductive layer (1) and the second composite thermal conductive layer (2).

8. The method for preparing a graphite-aluminum-metal composite thermal conductive sheet according to claim 6, characterized in that, The sintering process is carried out in a vacuum hot press furnace.

9. A method for preparing a graphite-aluminum-metal composite thermal conductive sheet according to claim 6, characterized in that, The sintering temperature is 670~710℃, the holding time is 0.5~1.5 h, and the pressure during sintering is 5~20 MPa.

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