Heat conduction structure and preparation method thereof, packaging structure and electronic equipment

Abstract

The invention relates to the technical field of heat dissipation, in particular to a heat conduction structure, a preparation method thereof, a packaging structure and electronic equipment. The heat conduction structure comprises a graphene interlayer and two thermal interface layers, the graphene interlayer comprises a plurality of graphene foam layers which are sequentially stacked, and the stacking direction of the graphene foam layers is perpendicular to the thickness direction of the heat conduction structure. In the thickness direction of the heat conduction structure, the two thermal interface layers are arranged on the two sides of the graphene interlayer correspondingly, and the two sides of each graphene foam layer make contact with the two thermal interface layers correspondingly. The multiple graphene foam layers included in the graphene interlayer can form multiple heat conduction channels in the thickness direction of the heat conduction structure, and heat transfer of the heat conduction structure in the thickness direction can be accelerated. The thermal interface layer can realize interface wetting and heat conduction efficiency balance on the two sides of the graphene interlayer, so that the heat conduction structure can be in good contact with other structures, the interface thermal resistance is reduced, and the overall thermal resistance of the heat conduction structure is further reduced.

Description

Technical Field

[0001] This application relates to the field of heat dissipation technology, and in particular to a heat-conducting structure, its preparation method, packaging structure, and electronic device. Background Technology

[0002] In existing technologies, heat dissipation of heat-generating devices is typically achieved using heat sinks. To ensure effective heat dissipation, a thermally conductive structure needs to be placed between the heat-generating device and the heat sink. This thermally conductive structure is thermally conductive, allowing heat from the heat-generating device to be quickly transferred to the heat sink, thereby accelerating heat exchange between the heat-generating device and the external environment.

[0003] Graphene is a commonly used thermally conductive material. However, current graphene thermally conductive structures have high interfacial thermal resistance, making it difficult to improve thermal conductivity and affecting heat dissipation. Summary of the Invention

[0004] This application provides a thermally conductive structure, its fabrication method, packaging structure, and electronic device. The thermally conductive structure has low thermal resistance and low compressive stress, can conduct heat quickly, and will not affect the assembly and application of the device.

[0005] Firstly, this application provides a thermally conductive structure that can be used for device heat dissipation. Specifically, the thermally conductive structure includes a graphene interlayer and two thermal interface layers. The graphene interlayer includes multiple graphene foam layers stacked sequentially, with the stacking direction of the multiple graphene foam layers perpendicular to the thickness direction of the thermally conductive structure. Each graphene foam layer can form a thermally conductive channel for heat conduction. Along the thickness direction of the thermally conductive structure, the two thermal interface layers are respectively disposed on both sides of the graphene interlayer. Both sides of each graphene foam layer are in contact with the two thermal interface layers, and each graphene foam layer can form a thermally conductive channel between the two thermal interface layers.

[0006] In the aforementioned thermally conductive structure, the multiple graphene foam layers within the graphene interlayer can form multiple thermally conductive channels along the thickness direction of the structure, accelerating heat transfer in that direction. The thermal interface layer achieves a balance between interfacial wetting and thermal conductivity efficiency on both sides of the graphene interlayer, allowing the thermally conductive structure to maintain good contact with other structures, reducing interfacial thermal resistance, and consequently decreasing the overall thermal resistance of the structure.

[0007] In some possible implementations, the graphene interlayer also includes multiple adhesive layers, with any two adjacent graphene foam layers along the stacking direction of the multiple graphene foam layers bonded together by the adhesive layers. Since the graphene foam layers in the graphene interlayer are bonded by adhesive layers, no compression is required, thus not increasing the density of the graphene interlayer, and consequently not increasing the compressive stress of the graphene interlayer. When the thermally conductive structure is used for heat conduction between two devices, the relatively small compressive stress will not affect the assembly and operation of the devices.

[0008] In some possible implementations, the adhesive layer comprises a substrate and two cured adhesive films. The two adhesive films are respectively disposed on both sides of the substrate along the stacking direction of the multiple graphene foam layers, with each adhesive film used to bond the graphene foam layer. The adhesive films on both sides of the adhesive layer have a cross-linked and cured structure, exhibiting pressure-sensitive properties, allowing the assembly of multiple graphene foam layers without significant compression. High-temperature baking is not required during the preparation process, which can improve production efficiency and reduce production costs.

[0009] The adhesive film can be any one or a combination of epoxy resin film, phenolic resin film, furfural resin film, polyurethane film, acrylic resin film, or silicone film. The substrate can be any one or a combination of polymer film, woven or nonwoven fabric layer, or metal foil.

[0010] In some possible implementations, the thickness of the adhesive layer is 1–10 μm, preferably 1–5 μm, along the stacking direction of the multiple graphene foam layers. The thickness of the graphene foam layer is 100–500 μm, preferably 150–350 μm. It should be understood that the above thicknesses can be achieved with an adhesive layer having a cured adhesive film, and the adhesive layer does not provide thermal conductivity.

[0011] In some possible implementations, the graphene foam layer can be selected as a porous structure, with each pore having a diameter of 10–100 μm, preferably 15–50 μm. The graphene foam layer constitutes 90 wt%–95 wt% of the total weight of the graphene interlayer. The density of the graphene foam layer is 0.10–0.50 g / cm³. 3 The lower density can further reduce the compressive stress of the graphene interlayer. For example, the compressive stress of the graphene interlayer under a 50% thickness compression condition is nearly half that of the compressive stress of a traditional carbon-based thermal pad under the same conditions. The reduction in compressive stress of the thermal conductive structure can effectively improve the pressure resistance limit of the heat dissipation system during the final product assembly process.

[0012] In some possible implementations, the thermal interface layer is made of any one or a combination of at least two of the following: phase change material, silicone grease, silicone gel, and liquid metal.

[0013] In some possible implementations, the thickness of the graphene interlayer is 0.1–10 mm, preferably 0.3–1 mm, and the thickness of each thermal interface layer is 0.5–20 μm, preferably 1–15 μm.

[0014] Secondly, this application provides a method for preparing a conductive structure, comprising:

[0015] Multiple graphene foam layers are stacked along the thickness direction of the graphene foam layers to form a graphene block.

[0016] The graphene block is cut along the thickness direction of the graphene foam layer to divide the graphene block into multiple graphene sandwich layers.

[0017] Thermal interface layers are provided on both sides of each graphene interlayer thickness direction, and each graphene foam layer is in contact with the two thermal interface layers on both sides along the graphene interlayer thickness direction.

[0018] In some possible implementations, stacking multiple graphene foam layers along the thickness direction of the graphene foam layers to form a graphene block includes:

[0019] Provide a graphene foam layer;

[0020] One graphene foam layer is bonded to another graphene foam layer on one side of the thickness direction using an adhesive layer. This step is repeated until multiple graphene foam layers are stacked sequentially along the thickness direction of the graphene foam layers.

[0021] In some possible implementations, bonding another graphene foam layer to one side of the graphene foam layer via an adhesive layer includes:

[0022] An adhesive layer structure is provided, the adhesive layer structure includes a substrate and two adhesive films respectively disposed on both sides of the thickness of the substrate, each adhesive film having a release film covering the surface opposite to the substrate.

[0023] The release film on the surface of one of the adhesive films in the adhesive layer structure is peeled off, and a graphene foam layer is bonded to one of the adhesive films.

[0024] The release film on the surface of another adhesive film is peeled off, and another graphene foam layer is bonded to the other adhesive film.

[0025] In some possible implementations, after cutting the graphene block along the thickness direction of the graphene foam layer to divide the graphene block into multiple graphene sandwich layers, and before setting thermal interface layers on both sides of each graphene sandwich layer along its thickness direction, the above preparation method includes:

[0026] Each graphene interlayer is cleaned and polished.

[0027] The graphene interlayer has fewer surface defects after cleaning and polishing, making it easier to set a thermal interface layer on the surface of the graphene interlayer, which can improve the bonding strength between the two.

[0028] Thirdly, this application provides a packaging structure including a circuit board, a heat-generating device, and a heat sink. This packaging structure can be a lidless package or a lidded package. The heat-generating device is disposed on the circuit board, and the heat sink is disposed on the surface of the heat-generating device facing away from the circuit board. A thermally conductive pad is disposed between the heat-generating device and the heat sink. The thermally conductive pad is any of the thermally conductive structures provided in the first aspect or prepared by any of the preparation methods provided in the second aspect. One thermal interface layer of the thermally conductive structure contacts the heat-generating device, and the other thermal interface layer contacts the heat sink. The low thermal resistance of the thermally conductive structure allows for rapid heat transfer from the chip to the heat sink, and the low compressive stress of the thermally conductive structure prevents excessive stress on the assembly of the chip and the heat sink, thus protecting the chip.

[0029] Fourthly, this application provides an electronic device including a housing and an encapsulation structure as described in the third aspect above, which is housed within the housing and enables good heat dissipation to ensure efficient operation of the electronic device. Attached Figure Description

[0030] Figure 1a This application provides a schematic diagram of the structure of a prior art graphene thermal conductive film during its preparation process.

[0031] Figure 1b This application provides a schematic diagram of the structure of a prior art graphene thermal conductive film during its preparation process.

[0032] Figure 1c This application provides a schematic diagram of the structure of a prior art graphene thermal conductive film during its preparation process.

[0033] Figure 2 This is a schematic diagram of the structure of an electronic device provided in an embodiment of this application;

[0034] Figure 3 This is a schematic diagram of a packaging structure provided in an embodiment of this application;

[0035] Figure 4a This is a schematic diagram of a heat-conducting structure provided in an embodiment of this application;

[0036] Figure 4b for Figure 4a Enlarged detail of the V-shaped area;

[0037] Figure 5 A schematic diagram showing a graphene foam layer of a thermally conductive structure bonded by an adhesive layer, as provided in an embodiment of this application.

[0038] Figure 6A flowchart illustrating a method for preparing a thermally conductive structure according to an embodiment of this application;

[0039] Figure 7a This is a schematic diagram of the fabrication process of a thermally conductive structure provided in an embodiment of this application;

[0040] Figure 7b This is a schematic diagram of the fabrication process of a thermally conductive structure provided in an embodiment of this application;

[0041] Figure 7c This is a schematic diagram of the fabrication process of a thermally conductive structure provided in an embodiment of this application;

[0042] Figure 8 A flowchart illustrating a method for preparing a thermally conductive structure according to an embodiment of this application;

[0043] Figure 9a This is a schematic diagram of the fabrication process of a thermally conductive structure provided in an embodiment of this application;

[0044] Figure 9b This is a schematic diagram of the fabrication process of a thermally conductive structure provided in an embodiment of this application;

[0045] Figure 9c This is a schematic diagram of the fabrication process of a thermally conductive structure provided in an embodiment of this application;

[0046] Figure 10 A flowchart illustrating a method for preparing a thermally conductive structure according to an embodiment of this application;

[0047] Figure 11a This is a schematic diagram of the fabrication process of a thermally conductive structure provided in an embodiment of this application;

[0048] Figure 11b This is a schematic diagram of the fabrication process of a thermally conductive structure provided in an embodiment of this application;

[0049] Figure 11c This is a schematic diagram of the fabrication process of a thermally conductive structure provided in an embodiment of this application;

[0050] Figure 12 This is a flowchart illustrating a method for preparing a thermally conductive structure according to an embodiment of this application.

[0051] Figure label:

[0052] 01-Graphene thermal conductive film; 02-Adhesive; 001-Thermal conductive pad;

[0053] 100 - Package structure; 10 - Circuit board; 20 - Chip; 30 - Heat sink; 40 - Thermal pad; 200 - Housing;

[0054] 1- Thermally conductive structure; 11- Graphene interlayer; 111, 111a, 111b- Graphene foam layers; 112- Adhesive layer; 1121- Substrate; 1122- Adhesive film; 12- Thermal interface layer. Detailed Implementation

[0055] With the development of electronic technology, the increased computing power of chips is accompanied by a significant increase in power consumption, posing a greater challenge to the chip's heat dissipation capabilities. To dissipate heat, thermal pads can be placed between the chip and the heat sink. These pads quickly conduct heat generated by the chip to the heat sink, where it is then dissipated through heat exchange with the external environment. To achieve high thermal conductivity, thermal pads can be made using graphene thermal conductive films, specifically as follows... Figure 1a As shown, multiple graphene thermally conductive films 01 are stacked and bonded together using adhesive 02 to form a block. The adhesive 02 used to bond the graphene thermally conductive films 01 has a low degree of cross-linking and is mostly gel-like, while the graphene films 01 have a high surface roughness. After multiple graphene thermally conductive films 01 are glued and stacked, it is necessary to... Figure 1b The block is compressed along the stacking direction to ensure complete contact between the adhesive 02 and the graphene thermally conductive film 01. Finally, as shown... Figure 1c As shown, the block is cut along the stacking direction of multiple graphene thermal conductive films 01 to form multiple thermal conductive pads 001, and the multiple graphene thermal conductive films 01 in each thermal conductive pad 001 are arranged along the thickness direction of the thermal conductive pad 001. See also... Figures 1a to 1c As shown, the increased bulk density of the compressed graphene thermal conductive film 01 leads to an increase in the internal compressive stress of the final thermal conductive pad 001. When applied to conduct heat between the chip and the heat sink, the chip may not be able to withstand the excessive compressive stress of the thermal conductive pad 001, resulting in stress failure.

[0056] Based on this, embodiments of this application provide a conductive structure and its preparation method, packaging structure, and electronic device. The conductive structure has low thermal resistance and does not require compression, thus achieving good thermal conductivity and ensuring the safety of contact devices.

[0057] To make the objectives, technical solutions, and advantages of this application clearer, the application will now be described in further detail with reference to the accompanying drawings.

[0058] Figure 2This application provides an embodiment of a terminal device, which may include mobile phones, tablets, laptops, servers, etc. Taking a server as an example, the heat-generating components of a server generally include a processor (central processing unit, CPU) and a video chip (GPU). Since the processor or GPU generates a large amount of heat during operation, to prevent overheating from affecting the performance of the processor or GPU, laptops typically use heat pipes or vapor chambers as heat-conducting components to dissipate heat from the processor or GPU. For example... Figure 2 As shown, a terminal device, taking a server as an example, includes a housing 200 and an encapsulation structure 100 disposed within the housing 200. The encapsulation structure 100 can be part of a processor. Specifically, the encapsulation structure 100 includes a circuit board 10, a chip 20, and a heat sink 30. The chip 20 is integrated into the circuit board 10 and generates heat during operation. The heat sink 30 is used to exchange the heat dissipated by the chip 20 with the air inside the housing 200. An air inlet K1 and an air outlet K2 are respectively provided on the front and rear sides of the housing 200, placing the encapsulation structure 100 between the air inlet K1 and the air outlet K2, thus placing it in the airflow path. Airflow from outside the housing 200 enters the housing 200 through the air inlet K1 to accelerate the heat exchange between the heat sink 30 and the airflow, and is discharged through the air outlet K2, thereby dissipating heat from the chip 20.

[0059] Figure 3 An example of a packaging structure 100 is provided, which includes a circuit board 10, a chip 20, a heat sink 30, and a thermal pad 40. The chip 20 is fixed to the circuit board 10 by soldering. The heat sink 30 is disposed on the side of the chip 20 facing away from the circuit board 10, and a thermal pad 40 is disposed between the heat sink 30 and the chip 20. The heat sink 30 is illustrated here as having multiple teeth, which increases the contact area between the heat sink 30 and the air, enhancing heat exchange and improving the heat dissipation rate. The thermal conductivity of the thermal pad 40 affects the effectiveness of directing heat from the chip 20 to the heat sink 30. The packaging structure 100 can be a cover-plate package or a coverless package; this application does not limit this.

[0060] like Figure 4a As shown, this application embodiment provides a thermally conductive structure 1, which can also be used as... Figure 3The thermal pad 40 in the image, and the thermally conductive structure 1, can also be referred to as a thermally conductive layer. Exemplarily, the thermally conductive structure 1 includes a graphene interlayer 11 and two thermal interface layers 12. The two thermal interface layers 12 are disposed on both sides of the graphene interlayer 11 along its thickness direction, making the thermally conductive structure 1 a sandwich structure. The arrow indicates the thickness direction of the thermally conductive structure 1, which can also be considered as the thickness direction of the graphene interlayer 11 and the thermal interface layers 12. This thermally conductive structure 1 is disposed in... Figure 3 In the packaging structure 100 shown, one thermal interface layer 12 is used to contact the chip 20, and another thermal interface layer 12 is used to contact the heat sink 30. Compared with the traditional technology where the graphene thermally conductive material directly contacts the heat sink and the chip, the thermal interface layer 12 in this thermally conductive structure 1 can effectively expel air between the thermally conductive structure 1 and the heat sink 30, and between the thermally conductive structure 1 and the chip 20, allowing the thermally conductive structure 1 to have a tighter contact with the heat sink 30 and the chip 20, reducing the thermal resistance caused by air, improving thermal conductivity, and balancing thermal conductivity efficiency. In implementation, the thickness of the thermal interface layer 12 can be precisely controlled to ensure unobstructed thermal conduction of the graphene interlayer 11 synapses. It should be understood that the thermally conductive structure 1 is generally arranged in a thin sheet shape between the heat-generating device and the heat-dissipating device in applications, and the thermally conductive structure 1 has a relatively thin thickness.

[0061] Figure 4b It shows Figure 4a The structure shown in the dashed box at point V. Refer to [the diagram / reference]. Figure 4a and Figure 4b As shown, the graphene interlayer 11 includes a plurality of graphene foam layers 111 stacked sequentially. The stacking direction of the plurality of graphene foam layers 111 is perpendicular to the thickness direction of the heat-conducting structure 1. The stacking direction of the plurality of graphene foam layers 111 can also be considered as the thickness direction of the graphene foam layers 111, which is perpendicular to the thickness direction of the heat-conducting structure 1. Each graphene foam layer 111 is oriented along the thickness direction of the heat-conducting structure 1. When heat is transferred through the graphene foam layer 111, it can be quickly conducted along the thickness direction of the heat-conducting structure 1 on the graphene foam layer 111, reducing the thermal resistance of heat transfer. For example, any two adjacent graphene foam layers 111 can be bonded together by an adhesive layer 112, with both sides of the adhesive layer 112 in the thickness direction bonded to the two graphene foam layers 111 respectively. Each graphene foam layer 111 contacts two thermal interface layers 12 on both sides along the thickness direction of the thermally conductive structure 1, forming a thermally conductive path along the thickness direction of the thermally conductive structure 1. This reduces the path length for heat dissipation, thereby reducing the thermal resistance of the graphene interlayer 11 and improving the thermal conductivity. In this thermally conductive structure 1, there is no need to compress the graphene interlayer 11, and no large compressive stress is formed within the graphene interlayer 11. When this thermally conductive structure 1 is used to dissipate heat from heat-generating devices such as chips, it will not pose a safety hazard to the structural function of the heat-generating devices.

[0062] Combination Figure 4a and Figure 4b The thermally conductive structure 1 shown can be considered to have an overall thermal resistance including the graphene interlayer 11 and the two thermal interface layers 12. Specifically, the adhesive layer 112 in the graphene interlayer 11 does not participate in heat conduction. Multiple graphene foam layers 111 can form multiple heat conduction channels arranged along the stacking direction. Each heat conduction channel can connect the two thermal interface layers 12 along the thickness direction of the thermally conductive structure 1. The in-plane thermal conductivity of the graphene foam layer 111 can reach 400-800 W / (m*K), and its orientation in the thickness direction of the thermally conductive structure 1 can achieve an effect similar to a heat pipe. For the entire thermally conductive structure 1, the thickness of the graphene interlayer 11 between the two thermal interface layers 12 is the minimum distance of the heat conduction channels. Each graphene foam layer 111 can be extended along the thickness direction of the thermally conductive structure 1 and perpendicular to the stacking direction of the multiple graphene foam layers 111, so that heat has the shortest heat conduction path between the two thermal interface layers 12, thereby accelerating heat dissipation. The stacked assembly of multiple graphene foam layers 111 is bonded using an adhesive layer 112, eliminating the need for compression or extrusion processes. This does not increase the density of the graphene interlayer 11, thus avoiding increased compressive stress and improving the overall structure's pressure resistance during final product assembly. For example, when assembling a packaging structure 100 that conducts heat between the chip 20 and the heat sink 30 via this thermally conductive structure 1, the lower compressive stress of the thermally conductive structure 1 reduces the risk of damage to the chip 20 due to excessive force when assembling the chip 20 and heat sink 30 using fasteners such as spring locks. This improves the structural strength and lifespan of the packaging structure 100.

[0063] The thickness of the entire heat-conducting structure 1 can be selected from 0.1 to 10 mm. The thickness of the graphene interlayer 11 can be selected from 0.1 to 10 mm, and in some embodiments, it can be selected from 0.3 to 1 mm. The thickness direction of the graphene interlayer 11 is perpendicular to the thickness direction of the heat-conducting structure 1. The graphene foam layer 111 adopts a porous structure, and the pore size of each pore can be selected from 10 to 100 μm. In some embodiments, the pore size of the graphene foam layer 111 can be selected from 15 to 50 μm. The density of the graphene foam layer 111 can be selected from 0.10 to 0.50 g / cm³. 3Compared with traditional technologies, the compressive stress of the low-density graphene interlayer 11 under 50% thickness compression is nearly half that of the traditional carbon-based thermal pad under the same conditions, which can further reduce the compressive stress of the graphene interlayer 11. The thickness of the graphene foam layer 111 can be selected from 100 to 500 μm. In some embodiments, the thickness of the graphene foam layer 111 is preferably 150 to 350 μm. In the graphene interlayer 11, the weight percentage of the graphene foam layer 111 is 90 wt% to 95 wt%. The thermal interface layer 12 can be any one or a combination of at least two of phase change materials, silicone grease, silicone gel, and liquid metal. The thickness of the thermal interface layer 12 can be selected from 0.5 to 20 μm, and in some embodiments 1 to 15 μm. The thermal interface layer 12 can be bonded to the graphene interlayer 11 by coating, dispensing, screen printing, or other methods.

[0064] It should be understood that the thickness of the thermal interface layer 12 can be selected according to the application scenario. If the thickness of the thermal interface layer 12 is too low, the wetting effect and air expulsion effect on both sides of the graphene interlayer 11 in the thickness direction may be poor, affecting structural stability and thermal conductivity. If the thickness of the thermal interface layer 12 is too high, it may form a shielding effect, increasing thermal resistance. In specific implementations, it is necessary to select an appropriate thickness of the thermal interface layer 12 according to the needs.

[0065] like Figure 5 As shown, the adhesive layer 112 in the graphene interlayer 11 exemplarily includes a substrate 1121 and two cured adhesive films 1122. The two adhesive films 1122 are respectively disposed on both sides of the substrate 1121 along the stacking direction of the plurality of graphene foam layers 111, and each adhesive film 1122 is used to bond the graphene foam layer 111. The adhesive film 1122 is a cured adhesive material, and the adhesive films 1122 on both sides of the adhesive layer 112 can directly bond and fix the two graphene foam layers 111 by bonding. The plurality of graphene foam layers 111 can be bonded sequentially by the plurality of adhesive layers 112 to form the graphene interlayer 11. The entire process eliminates the steps of graphite sheet impregnation, glue application, compression, and heat curing in the traditional processing process, which can effectively improve production efficiency. The adhesive films 1122 on both sides of the adhesive layer 112 are cross-linked and cured structures with pressure-sensitive properties, allowing multiple graphene foam layers 111 to be assembled without significant compression. The preparation process eliminates the need for high-temperature baking, improving production efficiency and reducing production costs.

[0066] The thickness of each adhesive layer 112 can be selected from 1 to 10 μm, and in some embodiments, it can be selected from 1 to 5 μm. The substrate 1121 includes any one or more combinations of polymer film, woven or nonwoven fabric layer, and metal foil. The adhesive film 1122 can specifically be any one or more combinations of cross-linked and cured epoxy resin film, phenolic resin film, furfural resin film, polyurethane film, acrylic resin film, or silicone film.

[0067] Figure 6 This application provides a method for preparing a thermally conductive structure, which can be used to prepare the thermally conductive structure described in the above embodiments. Figure 6 As shown, the preparation method includes:

[0068] S61: Multiple graphene foam layers are stacked along the thickness direction of the graphene foam layers to form a graphene block.

[0069] For example, such as Figure 7a As shown, multiple graphene foam layers 111 can be stacked by sequentially bonding them together with adhesive layer 112 to obtain a graphene block. Figure 7a The example illustrates two graphene foam layers 111 bonded together by an adhesive layer 112.

[0070] S62: Cut the graphene block along the thickness direction of the graphene foam layer to cut the graphene block into multiple graphene interlayers.

[0071] For example, such as Figure 7b As shown, it is cut using diamond wire or laser cutting methods. Figure 7b The graphene block in the middle has a cutting plane perpendicular to the stacking direction of the multiple graphene foam layers 111. Figure 7b The cutting position is indicated by a break line. A graphene block can be cut into at least two graphene interlayers 11, each with a thickness ranging from 0.1 to 10 mm. The number of cuts is selected based on the thickness of the graphene block and the required thickness of the graphene interlayers 11. Figure 7b The direction of the middle arrow is the thickness direction of each graphene interlayer 11, which is perpendicular to the stacking direction of the multiple graphene foam layers 111.

[0072] S63: Thermal interface layers are provided on both sides of each graphene interlayer thickness direction, and each graphene foam layer is in contact with two thermal interface layers on both sides along the graphene interlayer thickness direction.

[0073] For example, such as Figure 7c As shown, a thermal interface layer 12 is formed on both sides of the graphene interlayer 11 in the thickness direction by means of screen printing, coating, dispensing or other methods to obtain a thermally conductive structure 1.

[0074] It should be understood that the thermally conductive structure 1 is sheet-like, and a release film can be attached to both surfaces of the thermally conductive structure 1 during transportation to form a protective layer. In application, the release film can be removed for use.

[0075] In some embodiments, such as Figure 8 As shown, step S61 above, which involves stacking multiple graphene foam layers along the thickness direction of the graphene foam layers to form a graphene block, may specifically include:

[0076] S81: Provides a graphene foam layer;

[0077] The graphene foam layer 1 can be illustrated as a porous material.

[0078] S82: Adhere another graphene foam layer to one side of the thickness direction of one graphene foam layer using an adhesive layer, and repeat this step until multiple graphene foam layers are stacked sequentially along the thickness direction of the graphene foam layers.

[0079] Specifically, such as Figure 9a As shown, an adhesive layer 112 is bonded to one side of a graphene foam layer 111a in the thickness direction. Then, as... Figure 9b As shown, another graphene foam layer 111b is bonded to the side of the adhesive layer 112 opposite to the graphene foam layer 111a. Both sides of the adhesive layer 112 in the thickness direction are adhesive to bond the two graphene foam layers 111 together. Then, by repeating the step of bonding the graphene foam layer 111 to one side of the thickness direction of any graphene foam layer 111 using the adhesive layer 112, the following can be obtained: Figure 7a The graphene interlayer 11 shown. Figure 9c The example illustrates the structure of bonding graphene foam layers 111 and 111c and 111d by repeating the step of "bonding graphene foam layer 111 by adhesive layer 112" on one side of the thickness direction of graphene foam layer 111b. Alternatively, the graphene interlayer 11 can be obtained by repeating the step of "bonding graphene foam layer 111 by adhesive layer 112" on one side of the thickness direction of graphene foam layer 111a.

[0080] In some embodiments, the adhesive layer 112 is similar to Figure 5 The structure shown includes a substrate 1121 and two cured adhesive films 1122. The two adhesive films 1122 are respectively disposed on both sides of the substrate 1121 along the stacking direction of the plurality of graphene foam layers 111, and each adhesive film 1122 is used to bond the graphene foam layer 111. Figure 10 As shown, in step S82 above, bonding another graphene foam layer to one side of a graphene foam layer via an adhesive layer includes:

[0081] S101: Provides an adhesive layer structure, the adhesive layer structure including a substrate and two adhesive films respectively disposed on both sides of the thickness of the substrate, each adhesive film having a release film covering the surface of the adhesive film facing away from the substrate.

[0082] like Figure 11a As shown, the adhesive layer structure includes a substrate 1121 and two cured adhesive films 1122. To prevent the adhesive films 1122 from adhering to other substances when not in use, the adhesive layer structure also includes a release film M covering the surface of the adhesive films 1122. The substrate 1121 and the two cured adhesive films 1122 can be considered as... Figure 5 The adhesive layer 112 in the middle.

[0083] S102: Remove the release film from the surface of one of the adhesive films in the adhesive layer structure and bond a graphene foam layer to one of the adhesive films;

[0084] like Figure 11b As shown, the release film M of the adhesive layer on the surface of an adhesive film 1122 on the left side of the adhesive layer structure is peeled off, and a graphene foam layer 111a is bonded to the exposed adhesive film 1122 on the side away from the substrate 1121.

[0085] S103: Remove the release film from the surface of another adhesive film of the adhesive layer structure and bond another graphene foam layer to another adhesive film.

[0086] like Figure 11c As shown, the release film M of the adhesive layer on the surface of one adhesive film 1122 on the right side of the adhesive layer structure is peeled off, and another graphene foam layer 111b is bonded to the exposed adhesive film 1122 on the side away from the substrate 1121.

[0087] In some embodiments, Figure 12 This application provides a method for preparing a thermally conductive structure, which can be used to prepare the thermally conductive structure described in the above embodiments. Figure 12 As shown, the preparation method includes:

[0088] S121: Multiple graphene foam layers are stacked along the thickness direction of the graphene foam layers to form a graphene block;

[0089] S122: Cut the graphene block along the thickness direction perpendicular to the graphene foam layer to cut the graphene block into multiple graphene interlayers.

[0090] S123: Clean and polish each graphene interlayer;

[0091] S124: Thermal interface layers are provided on both sides of each graphene interlayer thickness direction, and each graphene foam layer is in contact with two thermal interface layers on both sides along the graphene interlayer thickness direction.

[0092] Wherein, step S121 is equivalent to Figure 6 Steps S61 and S122 in the text are equivalent to Figure 6 Steps S62 and S124 in the text are equivalent to Figure 6 Step S63 is omitted here. In step S123, cleaning and polishing the surface of the graphene interlayer 11 can reduce defects and stains on the surface of the graphene interlayer 11, which is beneficial to the bonding of the graphene interlayer 11 with the thermal interface layer 12 in step S124, strengthens the strength of the final thermally conductive structure 1, and also helps to ensure the thermal conductivity of the thermally conductive structure 1.

[0093] Next, this application will provide an exemplary analysis and description of a heat-conducting structure 1 provided in the embodiments of this application through several examples and comparative examples.

[0094] Example 1

[0095] The embodiment of this application provides a heat-conducting structure 1, the structure of which can be referred to as follows. Figure 4a and Figure 4b As shown, the thermally conductive structure 1 includes a graphene interlayer 11 and a thermal interface layer 12 disposed on both sides of the graphene interlayer 11 along its thickness direction. The graphene interlayer 11 includes multiple graphene foam layers 111 bonded together along a direction perpendicular to the thickness direction of the thermally conductive structure 1 by an adhesive layer 112. Any two adjacent graphene foam layers 111 can be connected by means of... Figure 5 The adhesive layers 112 shown are bonded together. During the preparation process, after the graphene block is cut to form the graphene interlayer 11, the thermal interface layer 12 is transferred to the surface of the graphene interlayer 11 in the thickness direction by screen printing.

[0096] The graphene interlayer 11 has a thickness of 0.3–1 mm, and each thermal interface layer 12 has a thickness of 15 μm. Each adhesive layer 112 has a thickness of 5 μm, and each graphene foam layer 111 has a thickness of 150 μm. The thermal interface layer 12 is a phase change material, mainly composed of paraffin wax and aluminum powder filler.

[0097] Example 2

[0098] The embodiment of this application provides a heat-conducting structure 1, the structure of which can be referred to as follows. Figure 4a and Figure 4b As shown, the thermally conductive structure 1 includes a graphene interlayer 11 and a thermal interface layer 12 disposed on both sides of the graphene interlayer 11 along its thickness direction. The graphene interlayer 11 includes multiple graphene foam layers 111 bonded together along a direction perpendicular to the thickness direction of the thermally conductive structure 1 by an adhesive layer 112. Any two adjacent graphene foam layers 111 can be connected by means of... Figure 5The adhesive layers 112 shown are bonded together. During the preparation process, after the graphene block is cut to form the graphene interlayer 11, the thermal interface layer 12 is transferred to the surface of the graphene interlayer 11 in the thickness direction by spraying with a precision spraying machine or screen printing.

[0099] The graphene interlayer 11 has a thickness of 0.3–1 mm, and each thermal interface layer 12 has a thickness of 10 μm. Each adhesive layer 112 has a thickness of 10 μm, and each graphene foam layer 111 has a thickness of 350 μm. The thermal interface layer 12 is a silicone gel, mainly composed of vinyl silicone oil and silica filler.

[0100] Example 3

[0101] The embodiment of this application provides a heat-conducting structure 1, the structure of which can be referred to as follows. Figure 4a and Figure 4b As shown, the thermally conductive structure 1 includes a graphene interlayer 11 and a thermal interface layer 12 disposed on both sides of the graphene interlayer 11 along its thickness direction. The graphene interlayer 11 includes multiple graphene foam layers 111 bonded together along a direction perpendicular to the thickness direction of the thermally conductive structure 1 by an adhesive layer 112. Any two adjacent graphene foam layers 111 can be connected by means of... Figure 5 The adhesive layers 112 shown are bonded together. During the preparation process, after the graphene block is cut to form the graphene interlayer 11, the thermal interface layer 12 is transferred to the surface of the graphene interlayer 11 in the thickness direction by a precision spraying machine.

[0102] The graphene interlayer 11 has a thickness of 0.3–1 mm, and each thermal interface layer 12 has a thickness of less than 5 μm. Each adhesive layer 112 has a thickness of 10 μm, and each graphene foam layer 111 has a thickness of 350 μm. The thermal interface layer 12 is a silicone grease, the main component of which is vinyl silicone oil.

[0103] Comparative Example 1

[0104] The thermally conductive structure provided in this comparative example includes a graphene interlayer 11. The graphene interlayer 11 includes multiple graphene foam layers 111 bonded together along a direction perpendicular to the thickness of the graphene interlayer 11 by an adhesive layer 112. Any two adjacent graphene foam layers 111 can be connected by means of... Figure 5 The adhesive layers 112 shown are bonded together. Other structures, parameters, and processes are the same. The thickness of the graphene interlayer 11 is 0.3-1 mm, the thickness of each adhesive layer 112 is 10 μm, and the thickness of each graphene foam layer 111 is 350 μm.

[0105] Comparative Example 2

[0106] The comparative example provides a thermally conductive structure comprising multiple graphene foam layers 111 stacked along the thickness direction, with any two adjacent graphene foam layers 111 bonded together by an adhesive. During fabrication, the adhesive is applied to the graphene foam layers 111 using a precision coating device. The thickness of the thermally conductive sheet is 0.3–1 mm, the adhesive thickness between any two graphene foam layers 111 is 30 μm, and the thickness of each graphene foam layer 111 is 350 μm. After bonding, the multiple graphene foam layers 111 undergo a 60% volume compression.

[0107] Comparative Example 3

[0108] The comparative example provides a thermally conductive structure including a graphene interlayer 11 and thermal interface layers 12 disposed on both sides of the graphene interlayer 11 along its thickness direction. The graphene interlayer 11 includes multiple graphene foam layers 111 bonded together along a direction perpendicular to the thickness of the thermally conductive structure 1 by an adhesive layer 112. Any two adjacent graphene foam layers 111 can be connected by means of... Figure 5 The adhesive layers 112 shown are bonded together. During the preparation process, after the graphene block is cut to form the graphene interlayer 11, the thermal interface layer 12 is transferred to the surface of the graphene interlayer 11 in the thickness direction by spraying with a precision spraying machine or screen printing.

[0109] The graphene interlayer 11 has a thickness of 0.3–1 mm, and each thermal interface layer 12 has a thickness of 30 μm. Each adhesive layer 112 has a thickness of 10 μm, and each graphene foam layer 111 has a thickness of 350 μm. The thermal interface layer 12 is a silicone gel, mainly composed of vinyl silicone oil and silica filler.

[0110] The above three embodiments and three comparative examples are summarized into Table 1.

[0111] Table 1

[0112]

[0113] The thermal resistance measurement method provided by ASTM 5470 was used to test the thermally conductive structures 1 provided in the three embodiments and the thermally conductive structures provided in the three comparative examples. The thermal resistance test results are shown in Table 2. The pressure during the test was 10–60 psi, the hot end temperature was 80°C, and three samples were used for each embodiment and each comparative example, with the average value taken.

[0114] Table 2

[0115] pressure Comparative Example 1 Comparative Example 2 Comparative Example 3 Example 1 Example 2 Example 3 10 0.72 0.95 0.51 0.33 0.39 0.26 20 0.54 0.62 0.48 0.31 0.26 0.23 30 0.44 0.53 0.46 0.30 0.21 0.20 40 0.39 0.48 0.44 0.28 0.18 0.19 50 0.34 0.46 0.43 0.27 0.17 0.18 60 0.31 0.44 0.42 0.26 0.16 0.17

[0116] The compressive stress test method provided by ASTM D575 was used to test the thermal conductive structures 1 provided in the three embodiments and the three comparative examples. The compressive stress test results are shown in Table 3. The indenter size was 25mm*25mm. During the test, each sample was compressed to 50% of its initial thickness at a speed of 25.4mm / min, then left to stand for 10 minutes before the residual compressive stress was read. The dimensions of each sample were 25*25*0.3mm.

[0117] Table 3

[0118] Comparative Example 1 Comparative Example 2 Comparative Example 3 Example 1 Example 2 Example 3 Compressive stress / psi 45.6 59.5 10.9 45.6 10.9 10.9

[0119] Based on Tables 1, 2 and 3, the heat-conducting structure 1 provided in the above embodiments and the heat-conducting structures provided in the three comparative examples are analyzed.

[0120] Referring to Comparative Examples 1 and 2, the graphene interlayer 11 in Comparative Example 1 is not compressed. According to Table 2, compressing the graphene interlayer 11 will increase the density of the graphene interlayer 11, thereby increasing the thermal resistance and compressive stress of the thermally conductive structure 1.

[0121] Referring to Comparative Example 1 and Embodiment 1, Comparative Example 1 has no thermal interface layer 12, while the thermally conductive structure 1 provided in Embodiment 1 has a thermal interface layer 12. Referring to Table 2, under the same thermal resistance test pressure, the thermally conductive structure 1 provided in Embodiment 1 has a lower thermal resistance, thus exhibiting better thermal conductivity. Referring to Table 3, the presence of the thermal interface layer 12 does not affect the compressive stress of the thermally conductive structure.

[0122] Referring to Comparative Example 3 and Example 2, the thermal interface layer 12 of the thermally conductive structure 1 provided in Example 2 has a smaller thickness. Referring to Table 2, under the same thermal resistance test pressure, the thermally conductive structure 1 provided in Example 2 has a lower thermal resistance, thus exhibiting better thermal conductivity. Referring to Table 3, the thickness of the thermal interface layer 12 does not affect the compressive stress of the thermally conductive structure.

[0123] Referring to Comparative Example 3, Example 2, and Example 3, the material of the thermal interface layer 12 in Comparative Example 3 and Example 2 is similar, while the material of the thermal interface layer 12 in Example 3 does not include fillers. Combined with Figure 2 As can be seen from the comparison between Comparative Example 3 and Example 2, the type of filler in the thermal interface layer 12 affects the thermal resistance. Furthermore, as can be seen from the comparison between Comparative Example 3 and Example 3, the main material in the thermal interface layer 12 that performs the heat conduction function is not the filler. According to Table 3, the material of the thermal interface layer 12 does not affect the compressive stress of the heat-conducting structure 1.

[0124] Referring to Comparative Example 1, Comparative Example 3, Example 1, Example 2, and Example 3, and in conjunction with Table 3, the materials of the thermal interface layer 12 with different materials have a significant impact on the compressive stress of the thermally conductive structure 1. The compressive stress of the thermally conductive structure 1 with the thermal interface layer 12 made of silicone gel or silicone grease is less than that of the thermally conductive structure 1 with the thermal interface layer 12 made of phase change material.

[0125] In summary, the thermally conductive structure 1 provided in this application embodiment, with thermal interface layers 12 on both sides of the graphene interlayer 11, can effectively reduce the thermal resistance of the thermally conductive structure 1, and the presence of the thermal interface layers 12 has little impact on the compressive stress of the thermally conductive structure. Multiple graphene foams 111 of the graphene interlayer 11 are sequentially bonded together by pre-formed adhesive layers 112, requiring no compression and thus not increasing the density of the graphene interlayer 11 and consequently increasing the compressive stress. Furthermore, the thermally conductive structure 1 does not require high-temperature baking during its fabrication, improving production efficiency and reducing costs. When applied to a heat dissipation system for heat-generating devices in electronic devices, the lower thermal resistance of the thermally conductive structure 1 accelerates the heat conduction and dissipation of the heat-generating devices. In addition, the thermally conductive structure 1 has low compressive stress, which does not pose a significant risk of pressure on the heat dissipation system, reducing the risk of damage to device assembly due to excessive pressure, and does not affect the assembly and application of other devices.

[0126] It should be understood that the heat-conducting structure 1 provided in the embodiments of this application can also be applied to other systems or structures that require heat conduction, especially in heat dissipation scenarios of high-density devices or high-efficiency chips, which can improve the heat dissipation effect.

[0127] The above are merely specific embodiments of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A thermally conductive structure, characterized in that, The thermally conductive structure includes a graphene interlayer and two thermal interface layers. The graphene interlayer includes multiple graphene foam layers stacked sequentially, with the stacking direction of the multiple graphene foam layers perpendicular to the thickness direction of the thermally conductive structure. Along the thickness direction of the thermally conductive structure, two thermal interface layers are respectively disposed on both sides of the graphene interlayer, and both sides of each graphene foam layer are in contact with the two thermal interface layers respectively.

2. The thermally conductive structure as described in claim 1, characterized in that, The graphene interlayer also includes multiple adhesive layers, and any two adjacent graphene foam layers along the stacking direction of the multiple graphene foam layers are bonded together by the adhesive layers.

3. The thermally conductive structure as described in claim 2, characterized in that, The adhesive layer includes a substrate and two cured adhesive films. The two adhesive films are respectively disposed on both sides of the substrate along the stacking direction of the plurality of graphene foam layers, and each adhesive film is used to bond the graphene foam layer.

4. The thermally conductive structure as described in claim 3, characterized in that, The adhesive film is any one or a combination of epoxy resin film, phenolic resin film, furfural resin film, polyurethane film, acrylic resin film or silicone film.

5. The heat-conducting structure as described in claim 3 or 4, characterized in that, The substrate includes any one or more combinations of polymer film, woven or nonwoven fabric layer, and metal foil.

6. The thermally conductive structure according to any one of claims 2-5, characterized in that, Along the stacking direction of the plurality of graphene foam layers, the thickness of the adhesive layer is 1 to 10 μm, and the thickness of the graphene foam layer is 100 to 500 μm.

7. The thermally conductive structure according to any one of claims 1-6, characterized in that, The graphene foam layer has a porous structure, with each pore having a diameter of 10–100 μm.

8. The thermally conductive structure according to any one of claims 1-7, characterized in that, In the graphene interlayer, the weight percentage of the graphene foam layer is 90wt% to 95wt%.

9. The thermally conductive structure according to any one of claims 1-8, characterized in that, The density of the graphene foam layer is 0.10–0.50 g / cm³. 3 .

10. The thermally conductive structure according to any one of claims 1-9, characterized in that, The thermal interface layer is made of any one or a combination of at least two of the following: phase change material, silicone grease, silicone gel, and liquid metal.

11. The thermally conductive structure according to any one of claims 1-10, characterized in that, Along the second direction, the thickness of the graphene interlayer is 0.1-10 mm, and the thickness of each thermal interface layer is 0.5-20 μm.

12. A method for preparing a conductive structure, characterized in that, include: Multiple graphene foam layers are stacked along the thickness direction of the graphene foam layers to form a graphene block. The graphene block is cut along the thickness direction of the graphene foam layer to cut the graphene block into multiple graphene interlayers; A thermal interface layer is provided on both sides of each graphene interlayer along the thickness direction, and each graphene foam layer is in contact with the two thermal interface layers on both sides along the thickness direction of the graphene interlayer.

13. The preparation method according to claim 12, characterized in that, The step of stacking multiple graphene foam layers along the thickness direction of the graphene foam layers to form a graphene block includes: Provide the aforementioned graphene foam layer; One graphene foam layer is bonded to another graphene foam layer on one side of the thickness direction of the graphene foam layer by an adhesive layer, and this step is repeated until multiple graphene foam layers are stacked sequentially along the thickness direction of the graphene foam layers.

14. The preparation method according to claim 13, characterized in that, The method of bonding another graphene foam layer to one side of the graphene foam layer via an adhesive layer includes: An adhesive layer structure is provided, the adhesive layer structure including a substrate and two adhesive films respectively disposed on both sides of the thickness of the substrate, each of the adhesive films having a release film covering the surface of the surface opposite to the substrate; Remove the release film from the surface of one of the adhesive films of the adhesive layer structure and bond a graphene foam layer to one of the adhesive films; Remove the release film from the surface of the other adhesive film of the adhesive layer structure and bond another graphene foam layer to the other adhesive film.

15. The preparation method according to any one of claims 12-14, characterized in that, After cutting the graphene block along the thickness direction of the graphene foam layer to divide the graphene block into multiple graphene sandwich layers, and before setting thermal interface layers on both sides of each graphene sandwich layer along its thickness direction, the preparation method includes: Each of the graphene interlayers is cleaned and polished.

16. A packaging structure, characterized in that, This includes circuit boards, heat-generating components, and heat sinks; The heating element is disposed on the circuit board, the heat sink is disposed on the surface of the heating element away from the circuit board, and a thermal pad is disposed between the heating element and the heat sink; The thermal pad is a thermally conductive structure according to any one of claims 1-11 or a thermally conductive structure prepared by the preparation method according to any one of claims 12-15, wherein one of the thermal interface layers of the thermally conductive structure is in contact with the heat-generating device, and the other thermal interface layer is in contact with the heat sink.

17. An electronic device, characterized in that, Includes a housing and a packaging structure as described in claim 16, which is housed within the housing.

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