A method of manufacturing a heat conducting device

Abstract

This application provides a method for fabricating a thermally conductive device, which includes at least the following steps: preparing a carbon thermally conductive substrate, wherein the carbon thermally conductive substrate includes alternating regions A and B. Masking treatment: masking the surface of region A with a protective film. Metal plating: plating a metal layer on the surface of the carbon thermally conductive substrate, so that the surface of region B is covered by the metal plating. Removing the protective film: restoring the masked region A. Folding and fixing: folding the component obtained in step d, stacking the spaced regions B after folding, and fixing the stacked regions B. By creating spaced plating regions, some areas of the device retain their original flexibility. This method fabricates a graphene-copper composite thermally conductive device that simultaneously possesses flexibility and improved longitudinal thermal conductivity. This method has advantages such as high yield, simple process, and suitability for mass production.

Description

Technical Field

[0001] This application relates to the field of thermal management, specifically to a method for fabricating a thermally conductive device. Background Technology

[0002] High temperatures severely impact the performance of most electronic components, with thermal failure being the most prevalent failure mode in electronic devices. The failure rate of electronic components increases exponentially with temperature; for every 10°C increase in temperature, the reliability of the device system decreases by 50%. In an era of miniaturization and high power in electronic devices, thermal design plays a crucial role in the development of new electronic products. Taking smartphones as an example, while device thickness continues to decrease, processor power continues to rise, making heat dissipation a growing concern and rendering thermal design increasingly important.

[0003] Currently, thermally conductive films made of carbon materials (such as graphene films, artificial graphite films, and graphite films) are widely used in the field of thermal management due to their excellent thermal conductivity and heat dissipation capabilities and high-temperature stability. However, the advantage of carbon thermally conductive films lies in their horizontal (in-plane) thermal conductivity, while their vertical thermal conductivity is relatively weak. Taking graphene films as an example, the horizontal thermal conductivity of currently commercially available graphene films is greater than 1000 W / (m·K), but their vertical thermal conductivity is typically less than 5 W / (m·K).

[0004] To improve the longitudinal thermal conductivity of graphene thermal conductive films, existing technologies employ a graphene-metal composite approach, leveraging the metal to enhance the longitudinal thermal conductivity of the graphene film. For example, Chinese invention patent "CN117560906A A Graphene-Metal Composite Film and Its Preparation Method" fills the through-holes of the graphene film substrate with copper, utilizing the uniform thermal conductivity of copper to improve the longitudinal thermal conductivity of the graphene film. However, this method suffers from low product yield, complex process flow, and difficulty in large-scale industrial production. Furthermore, product reliability is low, and the copper material within the through-holes can detach, potentially causing short circuits in the devices. Against this backdrop, the applicant has submitted a Chinese invention patent, "CN2024117255266 A Thermal Conductive Device," which involves depositing a metal coating on a monolithically formed carbon thermal conductive film, then connecting the ends of the film and folding it into a circular, polygonal, or irregular shape. The excellent in-plane thermal conductivity of the carbon thermal conductive film provides the entire device with a good in-plane thermal conductivity foundation. Furthermore, the carbon thermal conductive film, acting as a side component, can achieve longitudinal heat conduction. However, currently, there is no mature fabrication method for this device.

[0005] Against this background, providing a method for fabricating thermally conductive devices that can be mass-produced has become a technical problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0006] Some embodiments of this application provide a method for fabricating a thermally conductive device. By creating spaced-layer regions, some areas of the device retain their original flexibility. This method produces a graphene-copper composite thermally conductive device that simultaneously possesses flexibility and improved longitudinal thermal conductivity. This method has advantages such as high yield, simple process, and suitability for mass production, and can solve the technical problems existing in the background art.

[0007] The preparation method includes at least the following steps: a) Prepare a carbon thermally conductive substrate, wherein the carbon thermally conductive substrate includes alternating regions A and B; b) Masking treatment: The surface of area A is masked with a protective film; c) Applying a metal coating: Applying a metal coating to the surface of the carbon thermally conductive substrate, such that the surface of region B is covered by the metal coating. d) Remove the protective film and restore area A, which has been masked; e) Folding and fixing: Fold the component obtained in step d, and stack the spaced areas B after folding, and fix the stacked areas B.

[0008] This method aims to ensure that the thermally conductive device simultaneously achieves improved flexibility and longitudinal thermal conductivity. During fabrication, the carbon thermally conductive substrate is divided into regions: Region A is designated as the uncoated area, and Region B as the coated area. Region A is masked before coating and removed after coating to preserve its original flexibility. Region B is coated with a metal layer. The metal coating serves three purposes: firstly, it enhances the structural strength and connection reliability of the thermally conductive device; secondly, it provides welding points for the connection between the thermally conductive device and external heat sources (metal components); and thirdly, it improves the longitudinal thermal conductivity of the carbon thermally conductive substrate. Unlike carbon thermally conductive films, metals are isotropic thermally conductive materials; coating metals onto carbon thermally conductive films significantly improves their longitudinal thermal conductivity. Furthermore, by employing a folding mechanism, region A (the carbon thermally conductive substrate portion) serves as the side, while region B acts as the component in contact with the heat source and radiator. Region A retains its original flexibility and allows heat to be conducted longitudinally using the carbon thermally conductive substrate. The coating on the surface of region B enhances the connection between the thermally conductive device, the heat source, and the radiator. Additionally, the folding mechanism ensures proper device forming, enabling heat conduction between the heat source and the radiator through this thermally conductive device.

[0009] In a further technical solution, the carbon thermally conductive substrate is one or more of graphene film, artificial graphite film, and graphite film. The carbon thermally conductive substrate uses a carbon thermally conductive film, which, due to its excellent in-plane thermal conductivity, provides the entire thermally conductive device with a good in-plane thermal conductivity foundation. It also possesses flexibility and bend resistance. Metal plating is applied to certain areas to enhance longitudinal thermal conductivity. Furthermore, the folding method utilizes the in-plane thermal conductivity of the carbon material thermally conductive film to achieve longitudinal thermal conductivity. This method allows for the large-scale fabrication of a device with excellent in-plane and longitudinal thermal conductivity.

[0010] In a further technical solution, during the masking process, a removable polymer protective film is used to cover the surface of region A. To ensure that region A of the device retains its original flexibility, the method provided by this invention uses a mask to shield the carbon thermally conductive substrate, ensuring that region A will not be coated with a metal layer in the subsequent metal plating step. This polymer protective film can be made of waterproof and corrosion-resistant materials such as polyethylene, polypropylene, polyester, polyurethane, polyvinyl chloride, acrylic, or silicone. The polymer protective film has excellent shielding effect and is easy to remove without damaging the device.

[0011] In a further technical solution, the metal plating step employs one of the following methods: electroplating, physical vapor deposition, or chemical vapor deposition. The above only lists commonly used gold plating methods and processes; existing technologies that can achieve the same effect can also be applied to this method.

[0012] In a further technical solution, the metal coating is one or more of copper, iron, aluminum, gold, silver, nickel, and zinc.

[0013] In a further technical solution, before the metal plating or masking process, region B is perforated to create through-holes with a diameter ≥ 0.05 mm. The perforation method includes laser drilling or mechanical drilling. The shape of the through-holes is not limited, but the minimum diameter should be ≥ 0.05 mm to ensure a sufficiently tight bond between the metal plating and the substrate.

[0014] In a further technical solution, during the folding and fixing step, the stacked regions B are fixed by welding, riveting, or thermally conductive adhesive bonding. After folding, the regions B are stacked, and the fixing process ensures the formation of the thermally conductive device and reduces the thermal resistance of the stacked regions B. Welding is the preferred fixing method. Since regions B have a metal plating, soldering with solder paste increases the reliability of the stacked structure of regions B. Combined with a through-hole structure, the welding effect can be further improved. In addition, welding methods can also include solder paste reflow soldering, brazing, laser welding, and ultrasonic welding. Mechanical riveting can also tightly fix the stacked regions B, but the effect of reducing thermal resistance cannot reach the level of welding. Thermally conductive adhesive bonding is costly, and the effect of reducing thermal resistance is greatly affected by the thermally conductive adhesive itself.

[0015] In a further technical solution, the folded and fixed heat-conducting device includes two relatively parallel contact portions, which are either stacked or non-stacked regions B. Specifically, one of the parallel contact portions includes n regions B, and the other contact portion includes n+1 or n regions B, where n≥1. When this process reaches step d, the obtained semi-finished product is a heat-conducting film material with adjacent and alternating regions A and B. Therefore, after folding, various situations may occur. At least two relatively arranged regions B are required to achieve the effect of longitudinal heat conduction. Therefore, after folding, the relatively arranged regions B remain parallel, serving as contact portions connected to the heat source and radiator. Region A, located on the side, retains its original flexibility, serving as a functional component for longitudinal heat conduction. After folding and fixing, the integrally formed carbon heat-conducting film can be wound or folded into a circular, polygonal, or irregular shape with the ends connected. Relying on the excellent in-plane thermal conductivity of the carbon heat-conducting film, the entire heat-conducting device has a good in-plane thermal conductivity foundation.

[0016] In a further technical solution, a support member with compression resilience is provided between two parallel and opposite contact parts. The support member is an elastic member or foam. Specifically, the elastic member is a metal spring or a metal bracket. The foam is any one or more of graphene foam, graphite foam, EPE foam, PVC foam, EVA foam, PU foam, silicone foam, and EPDM foam. Attached Figure Description

[0017] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1This is a schematic diagram of the structure of a heat-conducting device according to an embodiment of this application; Figure 2 This is a schematic diagram of the structure of a heat-conducting device according to an embodiment of this application; Figure 3 This is a schematic diagram of the structure of a heat-conducting device with an embedded support in one embodiment of this application; Figure 4 This is a SEM image of cross-section B of the heat-conducting device according to an embodiment of this application; Figure 5 This is a schematic diagram of the working state of a heat-conducting device according to an embodiment of this application.

[0019] 1-Area A; 2-Area B; 3-Supporting component Detailed Implementation

[0020] The following detailed description of exemplary embodiments of this application refers to the accompanying drawings, which form part of the description, illustrating exemplary embodiments in which this application may be implemented. The more detailed description of embodiments of this application below is not intended to limit the scope of the claimed application, but is merely illustrative and does not limit the description of the features and characteristics of this application, in order to suggest the best mode for carrying out this application and sufficient to enable those skilled in the art to implement it. However, it should be understood that various modifications and variations can be made without departing from the scope of this application as defined by the appended claims. The detailed description and drawings should be considered illustrative only and not restrictive, and any such modifications and variations shall fall within the scope of this application described herein. Furthermore, the background art is intended to illustrate the current state of research and development and significance of the technology, and is not intended to limit this application or its application areas.

[0021] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used herein in the specification of this application is for the purpose of describing particular embodiments only and is not intended to limit the application; the term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0022] It should be understood that in this application, "connection" and "connected" can both refer to a mechanical or physical connection relationship. For example, "connected to B" or "connected to B" can mean that there are fastening components (such as screws, bolts, rivets, etc.) between A and B, or that A and B are in contact with each other and are difficult to separate.

[0023] Unless otherwise specified in the examples, the procedures should be performed under standard conditions or conditions recommended by the manufacturer. Reagents or instruments whose manufacturers are not specified are all commercially available products.

[0024] To facilitate understanding of the technical solution of this application, the technical problem of this application will be described first below.

[0025] The poor vertical thermal conductivity of graphene thermal conductive films is a significant issue, and its vertical thermal conductivity needs improvement for use as a TIM (Thermal Insulation Material). To address this, the applicant has designed an existing graphene thermal conductive film by combining it with a metal, leveraging the isotropic thermal conductivity of the metal to improve the vertical thermal conductivity of the graphene thermal conductive film. Specifically, this is illustrated in Chinese invention patent "CN2024117255266 A Thermal Conductive Device," which involves coating a portion of a one-piece carbon thermal conductive film with a metal layer, then folding or wrapping it end-to-end into a circular, polygonal, or irregular shape. The metal-coated portions are connected to the heat source and heat sink, respectively. The excellent in-plane thermal conductivity of the carbon thermal conductive film provides a good in-plane thermal conductivity foundation for the entire device. However, a mature process for the mass production of this device is currently lacking.

[0026] This application provides a method for fabricating a thermally conductive device, which includes at least the following steps: a) Prepare a carbon thermally conductive substrate. In this embodiment, the carbon thermally conductive substrate is a graphene thermally conductive film. The carbon thermally conductive substrate includes alternating regions A1 and B2; the areas of regions A1 and B2 can be the same, or they can be two regions with different areas. In this embodiment, the areas of regions A1 and B2 are equal. In some embodiments of this application, the carbon thermally conductive substrate can also be one or more of artificial graphite films and graphite films.

[0027] b) Masking treatment: Prepare a polymer protective film. Ensure the polymer protective film is undamaged and has good sealing, waterproof, and corrosion-resistant properties. Apply the polymer protective film to area A1, ensuring that all areas of A1 are properly masked.

[0028] c) Metal plating: The semi-finished product, which has been masked in step b, is immersed in an electrolytic cell containing a 1 mol / L copper sulfate dilute sulfuric acid solution, with the pH value of the electrolyte controlled within the range of 0.5-2. The cathode electrode is connected to the graphene film, and a copper ball is used as the electrolytic anode. A 1A DC current is applied, and after 30 minutes, when region B2 is observed to have a distinct metallic luster, the current is stopped and the product with the metal plating layer is removed. There are various methods for metal plating; this embodiment only lists one of the most commonly used plating methods in the current industrial stage. The same effect can be achieved by methods such as physical vapor deposition or chemical vapor deposition. In some embodiments of this application, the metal plating layer is a common metal with good thermal conductivity, such as iron, aluminum, gold, silver, nickel, or zinc. After the above steps, the product is obtained as shown in the figure. Figure 1 The device shown in 1a. At this time, the carbon thermally conductive substrate is integrally formed, and a metal plating layer is provided on the surface of region B2 of the carbon thermally conductive substrate.

[0029] d) Remove the protective film. Tear off the polymer protective film covering area A1 obtained in step c. During the tearing process, be careful not to damage the coating on area B2. Alternatively, use a solution that can dissolve the polymer protective film to rinse and remove the polymer protective film.

[0030] e) Folding and fixing: Fold the component obtained in step d using a winding jig. Regions A1 and B2 are stacked according to their respective regions. The folding process can be done manually or automatically by machine. The folded heat-conducting device includes two relatively parallel contact portions, which are either stacked or non-stacked regions B2. Region A1 is also stacked and located on the side of the contact portion formed by region B2. A gap is left between the two relatively parallel contact portions, and region A1 on the side is curved and arched.

[0031] In some embodiments of this application, the folded and fixed heat-conducting device includes two relatively parallel contact portions, which are either stacked or non-stacked regions B, such as... Figure 1 As shown in Figure 1c, one of the contact portions includes one region B, and the other contact portion, which is disposed opposite to it, includes two regions B stacked together.

[0032] In some embodiments of this application, the folded and fixed heat-conducting device includes two relatively parallel contact portions, which are the stacked regions B, such as... Figure 2 As shown in 2c, one of the contact portions includes four regions B stacked together, and the other contact portion, which is disposed opposite to it, includes four regions B stacked together.

[0033] In the fixing step, the already stacked areas B2 are soldered and fixed by solder paste reflow soldering. Specifically, before folding, solder paste is first printed on the surface of area B2, and then folding is performed so that multiple areas B2 are stacked. After the stacked areas B2 are simply physically fixed, they are sent to the reflow oven for reflow soldering.

[0034] In some embodiments of this application, the fixing step employs brazing, in which a metal filler metal is coated onto the surface of region B2. The metal filler metal can be in paste or sheet form, and then folded to allow multiple regions B2 to be stacked. After being heated in a vacuum furnace, the metal filler metal melts and fixes the stacked regions B2 in place.

[0035] In some embodiments of this application, the fixing step employs laser welding, whereby region B2 is laminated and then fixed using a laser welding device.

[0036] In some embodiments of this application, the fixing step employs ultrasonic welding, whereby region B2 is laminated and then fixed using an ultrasonic welding device.

[0037] After the above steps, the top view of the heat-conducting device after being surrounded is as follows. Figure 1 As shown in 1b, the front view is as follows Figure 1 As shown in Figure 1c, the carbon thermally conductive substrate has metal coatings at both ends. The carbon thermally conductive substrate is wound into a hollow structure, and the metal coatings at both ends of the carbon thermally conductive substrate are welded together, providing a reliable physical connection for the thermally conductive device. Because the carbon thermally conductive substrate is integrally molded and has high in-plane thermal conductivity, winding it into a hollow structure gives the entire thermally conductive device superior in-plane thermal conductivity. Metal is an isotropic thermally conductive material, and the metal coating enhances the longitudinal thermal conductivity of the carbon thermally conductive film, strengthens the support strength of the thermally conductive device, and also enables the thermally conductive device to be welded.

[0038] In some embodiments of this application, before applying the metal plating layer, the region B2 is perforated. The perforation method includes laser perforation or mechanical perforation. The product with the shielded region A1 placed on the perforation station is then perforated using a laser perforation machine, CNC machine tool, or precision drilling equipment. The cross-sectional shape of the hole can be circular, square, triangular, etc., and the shape of the resulting through-hole is unrestricted. It is only necessary to ensure that the minimum diameter of the through-hole is ≥0.05mm to ensure a sufficiently tight bond between the metal plating layer and the substrate.

[0039] In some embodiments of this application, area B2 is perforated before the masking process. Similarly, a laser drilling machine, CNC machine tool, or precision drilling equipment is used to perforate the thermal conductive film. The cross-sectional shape of the hole can be circular, square, triangular, etc., and the shape of the processed through-hole is unrestricted. It is only necessary to ensure that the minimum diameter of the through-hole is ≥0.05mm to ensure a sufficiently tight bond between the metal plating and the substrate. Simultaneously, after perforation, the solder paste and brazing filler metal used in the soldering step can penetrate deep into the through-hole, further improving the longitudinal thermal conductivity and soldering effect. The SEM image of the metal plating layer after perforation in area B is shown below. Figure 4 As shown.

[0040] In some embodiments of this application, a support member with compression resilience is provided between two parallel, opposite contact portions. This support member can be an elastic element or foam. Since the flexibility provided by carbon thermally conductive substrates is limited, and they may lose their resilience under high compression rates, the support member can improve the compression resilience performance of the thermally conductive device. Figure 3 As shown, the support member has compression resilience. Figure 3 The supporting material shown in 3a is an elastic element. Figure 3 The supporting material shown in 3b is foam. In some heat dissipation scenarios, there is not only a need for heat dissipation, but also a need for cushioning. Taking the heat dissipation of the under-display fingerprint area of ​​3C products as an example, while dissipating heat, it is also necessary to provide necessary support and cushioning for the screen. The presence of the uncoated metal carbon thermal conductive film gives the thermal conductive device a certain degree of deformation capability and deformable space. The material with compressibility and resilience filling the hollow part of the thermal conductive device gives it compressibility and resilience. The combined effect of these two factors gives the thermal conductive device both support and cushioning functions.

[0041] The thermally conductive device prepared by the method provided in this invention can be applied in the following scenarios: Figure 5 A heat-conducting device is welded between external components A and B, where A is the heat source and B is the component to conduct and receive heat. The carbon thermally conductive substrate of the heat-conducting device is a graphene thermally conductive film. Region B2 of the heat-conducting device has two relatively parallel upper and lower surfaces with metal coatings, which contact external components A and B respectively to achieve heat conduction between A and B.

[0042] When heat is dissipated from component A, thanks to the superior longitudinal thermal conductivity of the copper-plated graphene film, the heat is transferred along the longitudinal direction of the copper-plated graphene film. At the same time, thanks to the good in-plane thermal conductivity of the thermal conductive device, the heat reaching the copper-plated graphene film is quickly transferred through multiple paths to the copper-plated graphene film in contact with component B, and finally reaches component B.

[0043] Meanwhile, when component A or B is squeezed, the heat-conducting device has a certain degree of deformability, thus providing a buffering effect. When component A or B is subjected to multiple squeezes, the graphene film will not break due to its ≥100,000 bending resistance.

[0044] Figure 5 The thermal conductive device shown is connected to each other by welding. Compared with the method of using adhesive, the connection has better reliability, and the presence of metal plating improves the structural strength of the thermal conductive device.

[0045] It is worth mentioning that one of the advantages of the thermal conductive device provided in this application embodiment is that it has better longitudinal thermal conductivity, but it also has good thermal conductivity in all directions. The specific application direction and application method of the thermal conductive device with the structure described in this application are not limited.

[0046] The above description describes specific embodiments of this application, but the scope of protection of this application is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in this application, and these modifications or substitutions should all be covered 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 method for fabricating a thermally conductive device, characterized in that, At least the following steps are included: a) Prepare a carbon thermally conductive substrate, wherein the carbon thermally conductive substrate includes alternating regions A and B; b) Masking treatment: The surface of area A is masked with a protective film; c) Applying a metal coating: Applying a metal coating to the surface of the carbon thermally conductive substrate, such that the surface of region B is covered by the metal coating. d) Remove the protective film and restore area A, which has been masked; e) Folding and fixing: Fold the component obtained in step d, and stack the spaced areas B after folding, and fix the stacked areas B.

2. The method for preparing a thermally conductive device according to claim 1, characterized in that: In the masking process, a polymer protective film is used to cover the surface of area A.

3. The method for preparing a thermally conductive device according to claim 1, characterized in that: The metal plating process can be carried out using one of the following methods: electroplating, physical vapor deposition, or chemical vapor deposition.

4. The method for fabricating a thermally conductive device according to claim 1, characterized in that: Before performing the metal plating or masking process, the area B is drilled to create through holes with a diameter ≥ 0.05 mm.

5. The method for fabricating a thermally conductive device according to claim 4, characterized in that: Drilling methods include laser drilling or mechanical drilling.

6. The method for preparing a thermally conductive device according to claim 1, characterized in that: The metal plating is one or more of copper, iron, aluminum, gold, silver, nickel, and zinc.

7. A method for preparing a thermally conductive device according to claim 1 or 5, characterized in that: In the folding and fixing step, the stacked areas B are fixed by welding, riveting or thermally conductive adhesive bonding.

8. The method for preparing a thermally conductive device according to claim 1, characterized in that: The heat-conducting device after folding and fixing includes two relatively parallel contact portions, which are either stacked or not stacked in region B.

9. The method for preparing a thermally conductive device according to claim 8, characterized in that: Two parallel and opposite contact parts, one of which includes n regions B, and the other contact part which is opposite to it includes n+1 or n regions B, where n≥1.

10. The method for preparing a thermally conductive device according to claim 9, characterized in that: A support member with compression resilience is provided between two parallel and opposite contact parts. The support member is an elastic element or foam. Specifically, the elastic element is a metal spring or a metal bracket. The foam is any one or more of graphene foam, graphite foam, EPE foam, PVC foam, EVA foam, PU foam, silicone foam, and EPDM foam. The carbon thermally conductive substrate is one or more of graphene film, artificial graphite film, and graphite film.

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