Graphene-reinforced thermal interface material and method for preparing same
Through the combination of graphene fibers and polymer materials, a thermal interface film with high thermal conductivity is manufactured, which solves the problem of insufficient thermal conductivity of traditional thermal interface materials and achieves more effective heat dissipation of electronic equipment.
Patent Information
- Application Number
- CN202380070854.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Priority Date
- 2022-10-11
- Filing Date
- 2023-10-03
- Publication Date
- 2025-06-13
AI Technical Summary
The thermal conductivity of traditional thermal interface materials is insufficient and it is difficult to effectively dissipate heat, which limits the performance and life of electronic devices.
The thermal interface film is made by using a method of combining graphene fibers and polymer materials, which penetrate through the openings of the template and cut after polymer penetration to form the thermal interface film.
The vertical thermal conductivity of thermal interface materials is significantly improved, reaching 10W/mK to 200W/mK, while maintaining mechanical properties and is suitable for heat dissipation of electronic devices.
Smart Images
Figure CN120153476A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the field of microelectronic packaging, and particularly to a thermal interface material where heat dissipation is a key issue. Background Art
[0002] With the continuous development of modern electronic devices and systems, their increasing power density has also led to higher operating temperatures. Therefore, effective thermal management has become extremely important for removing the large amount of heat required to ensure high performance and long-life reliability. The thermal conductivity of traditional thermal interface materials (TIMs) is a very important heat dissipation factor, usually less than the maximum value of 10 W / mK, and typically around 4 or 5 W / mK in the vertical direction. Therefore, to solve this problem, great efforts have been made to develop high-performance TIMs based on carbon materials such as graphene nanoplatelets, carbon nanotubes, and carbon fibers.
[0003] However, there is still room for further improvement in graphene-reinforced thermal interface materials. Summary of the Invention
[0004] In view of the above and other drawbacks of the prior art, an object of the present invention is to provide an improved high-thermal conductivity interface material and a method for manufacturing such a material.
[0005] According to a first aspect of the present invention, there is provided a method for manufacturing a thermal interface film, the method comprising: providing a template including a plurality of openings therethrough; disposing graphene fibers through the openings; attaching a support plate on at least one side of the template such that the graphene fibers are attached to the support plate; removing the template to expose the graphene fibers; infiltrating the graphene fibers with a polymer material to form a polymer-infiltrated graphene fiber block; and cutting the polymer-infiltrated graphene fiber block in a direction perpendicular to the extension of the graphene fibers to form a thermal interface film.
[0006] Herein, the template can be regarded as a support structure for forming a plurality of graphene fibers, where the support structure is subsequently removed.
[0007] Graphene fibers have been shown to have a very high thermal conductivity, exceeding 1000 - 2000 W / mK. The object of the present invention is to implement graphene fibers in a polymer material to form a thermal interface material with high thermal conductivity in the vertical direction. A material being referred to as a film should be interpreted to mean that the extension in the xy plane is generally much greater than the thickness of the film. Thus, the vertical direction is regarded as the direction perpendicular to the xy plane of the film, i.e., the z direction. The thermal interface film can be formed into a disk or patch of appropriate size, for example, arranged between a heat-generating electrical component and a cooling component.
[0008] In particular, the present invention is based on the recognition that a thermal interface film of graphene fibers having any suitable configuration and arrangement can be easily achieved by using a template that is subsequently removed. Thus, the graphene-based film can be customized by adjusting the template configuration to suit different applications. In addition, the thermal interface film can significantly improve the thermal performance in the vertical direction while maintaining the mechanical properties in the in-plane direction of the thermal interface film.
[0009] The thermal interface film produced by the method can be referred to as a graphene-based film or a graphene-reinforced film, wherein the thermal conductivity in the vertical direction is improved by graphene fibers.
[0010] According to one embodiment of the present invention, the method further includes: flattening the top surface of the polymer-permeated graphene fiber block before cutting the block to improve the smoothness of the film surface, thereby providing improved heat transfer.
[0011] According to one embodiment of the present invention, removing the template includes etching away the template. The template can be made of a plastic material such as polyethylene or polypropylene, or can be made of, for example, alumina. By etching away the template, the graphene fibers will be exposed and retain the shape and configuration of the template through-holes.
[0012] According to one embodiment of the present invention, the support plate is made of a metal such as copper or steel. In addition, in the embodiment where the template is etched away, the bottom plate is made of a material resistant to the etching technique used to remove the template, such that the bottom plate remains after etching.
[0013] According to one embodiment of the present invention, attaching the support plate includes: adhering the plate to the template and the graphene fibers, for example, by using an epoxy-based glue. The support plate thus forms a bottom plate from which the graphene fibers will protrude after the template is removed. In addition to epoxy-based glues, other materials such as acrylic and polyurethane-based adhesives can also be used. Epoxy resins provide strength and good adhesion to many substrates, while acrylic resins provide good elasticity, and polyurethane-based adhesives can be used for most bonding surfaces. Thus, different adhesives have different properties and different advantages, enabling the selection of the most suitable adhesive for a given application.
[0014] According to one embodiment of the present invention, the method further includes: providing a mold around the template, the mold including solid walls to contain a polymer material. The mold can be a box-shaped object having the same shape as the template, which is arranged to contain the polymer material during the graphene fiber infiltration. In addition, the mold can be attached to the bottom plate to form a closed seal to prevent leakage of the liquid polymer material. A mold including a support plate can also be provided, that is, attaching the support plate simultaneously includes arranging the mold around the template.
[0015] According to an embodiment of the present invention, the graphene fiber through - opening is provided with stitching fibers. The graphene fibers can be arranged on a roll similar to a thread, in which case, a sewing machine can be used to pass the fibers through the openings of the template. Using stitching provides a fast and easily achievable method for mass - producing the thermal interface film.
[0016] According to an embodiment of the present invention, the method further includes: before arranging the graphene fibers in the openings, braiding and / or twisting the graphene fibers. Thereby, the mechanical and thermal properties of the graphene fibers can be changed before arranging the graphene fibers in the template. For example, stitching may require fibers with high mechanical strength and flexibility, which can be achieved by twisting and / or braiding the fibers in a manner similar to ropes and steel wires.
[0017] According to an embodiment of the present invention, the method includes: attaching support plates to two opposite sides of the template. Once the template is removed, the two opposite support plates can fix the graphene fibers in place.
[0018] According to a second aspect of the present invention, there is provided a thermal interface film, the thermal interface film comprising: a plurality of region portions composed of graphene fibers penetrated by a polymer, wherein the graphene fibers extend in a direction perpendicular to the plane of the film; and wherein the plurality of region portions of the graphene fibers penetrated by the polymer are surrounded, and the fibers contain the polymer.
[0019] The thermal interface film prepared by the method described above can be configured to have a thermal conductivity in the direction perpendicular to the plane of the film of 10 W / mK to 200 W / mK. The heat resistance and thermal conductivity can be determined using the method according to ASTM 5470 standard.
[0020] According to an embodiment of the present invention, the amount of graphene fibers in the thermal interface film is 5 vol% to 90 vol%.
[0021] According to an exemplary embodiment, the graphene fibers penetrated by the polymer may include continuous graphene fibers extending from the top surface to the bottom surface of the thermal interface film.
[0022] According to an exemplary embodiment, the graphene fibers penetrated by the polymer may include braided graphene fibers.
[0023] According to an exemplary embodiment, the graphene fibers penetrated by the polymer may include twisted graphene fibers.
[0024] According to an exemplary embodiment, the graphene fibers penetrated by the polymer may include graphene fibers reinforced with graphene sheets.
[0025] The effects and features of the second aspect of the present invention are similar to the advantages discussed above with respect to the first aspect.
[0026] Other features and advantages of the present invention will become apparent when studying the appended claims and the following description. Those skilled in the art will recognize that different features of the present invention can be combined without departing from the scope of the present invention to produce embodiments other than those described below. BRIEF DESCRIPTION OF THE DRAWINGS
[0027] These and other aspects of the present invention will now be described in more detail with reference to the drawings showing exemplary embodiments of the present invention, in which:
[0028] Figure 1A -G schematically shows the method steps according to an embodiment of the present invention;
[0029] Figure 2 is a flowchart outlining the method steps according to an embodiment of the present invention; and
[0030] Figure 3A -B schematically shows the features of the method according to an embodiment of the present invention.
[0031] DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS
[0032] The present invention will now be described more fully hereinafter with reference to the drawings, in which the presently preferred embodiments of the present invention are shown. However, the present invention may be embodied in many different forms and should not be limited to the embodiments described herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the present invention to those skilled in the art. Like reference numerals refer to like elements throughout.
[0033] Figure 1A -F schematically shows a method of manufacturing a thermal interface film according to an embodiment of the present invention, which will be further referred to in FIG. 1 Figure 2 for description, Figure 2 showing a flowchart outlining the method steps. In Figure 1A -F, the left figure is a cross-sectional view, and the right figure is a top view schematically showing the method steps of manufacturing.
[0034] First, a template 100 is provided, as Figure 1A shown. The template includes a plurality of openings 102 passing through the template. Thus, the template is a block of material including through-holes for placing graphene fibers. In addition, it should be noted that the images are not drawn to scale or proportion. The height of the template 100 and the size and spacing of the through-holes 102 can be selected to provide a resulting thermal interface film having the desired properties. For example, the diameter of the openings is 5 μm to 5 mm, and the depth is 1 mm to 20 cm.
[0035] The next step includes: disposing the graphene fiber 104 through the opening 102. Figure 3A -B schematically shows an exemplary embodiment, in which, using, for example, a loom, the graphene fiber 104 is stitched or woven through the opening 102 of the template 100, thus facilitating rapid large-scale production. However, the fiber strands can also be individually disposed in each opening manually or by a robot.
[0036] The manufacture of the graphene fiber has been described elsewhere, and thus only a general description will be provided herein. The formation of the graphene fiber begins with the manufacture of graphene oxide (GO) flakes, which are subsequently dispersed in water. The graphene fiber is formed from a mixture containing GO flakes by electrospinning or melt spinning. The spun fiber can then be twisted and / or woven to form the fiber or fiber bundle used in the present invention. The fiber can also be immersed in a bath containing graphene flakes to enhance the fiber. The graphene fiber can be a continuous graphene fiber with a length of 0.1 cm to 100 cm. Thus, the graphene fiber can be formed such that the diameter of the fiber corresponds to the diameter of the opening 102 in the template 100.
[0037] Once the graphene fiber is disposed in the opening, as Figure 1B shown, the support plate 106 is attached 204 to at least one side 108 of the template such that the graphene fiber is attached to the support plate. In Figure 1C the embodiment shown, the support plate 106 is attached to the bottom surface 108 of the template 100. Optionally, a second support plate (not shown) can be attached to the top surface of the template 100. The support plate is attached to the template and the graphene fiber by an epoxy-based glue.
[0038] Subsequent steps include: removing 206 the template 100 to expose the graphene fiber 104, as Figure 1D shown. For example, a polyester template can be etched away in an aqueous NaOH solution. Chromic acid can be used to etch polypropylene. Alumina can be etched away using a solution based on phosphoric acid and nitric acid.
[0039] After removing the template 100, the graphene fiber 104 still protrudes from the bottom plate 106, and if a top plate is used, the fiber will be sandwiched between the top plate and the bottom plate.
[0040] The next step includes: infiltrating 208 the graphene fiber 104 with a polymer material 110 to form a polymer-infiltrated graphene fiber block 112. As Figure 1EAs shown, the mold 120 is disposed around the graphene fibers 104 to accommodate the polymer material 110 during infiltration. The mold 120 can include four sidewalls and can be attached to the bottom plate 106. However, the mold 120 can also be box-shaped such that the mold 120 includes a bottom plate 106 attached to the template 100. Thus, when the template 100 is removed, the mold 120 is already in place. A mold 120 with a lid can also be used to completely enclose the graphene fibers 104 during infiltration with the polymer material 110.
[0041] Figure 1F Schematically shows the polymer-infiltrated graphene fiber block 112 after removal of the mold 120 and the bottom plate 106.
[0042] As Figure 1G shown, the final step includes: cutting 210 the polymer-infiltrated graphene fiber block 112 along a direction perpendicular to the extension of the graphene fibers to form the thermal interface film 114. As Figure 1F shown, the cutting is performed in the xy plane such that the resulting thermal interface film 114 includes a plurality of regional portions composed of polymer-infiltrated graphene fibers 104, wherein the extension of the graphene fibers 104 is in a direction perpendicular to the plane of the film 114, i.e., the z direction. In addition, the plurality of regional portions of the polymer-infiltrated graphene fibers 104 are surrounded by the polymer material 110. The cutting can be performed using any suitable cutting method, for example, sawing, plasma cutting, water jet milling, wire cutting, etc.
[0043] The graphene content in the final thermal interface film 114 can be from 5 vol% to 90 vol%. In one exemplary embodiment, the graphene content in the final thermal interface film 114 is from 30 vol% to 40 vol%.
[0044] The method shown can also include: flattening the top surface and / or the bottom surface of the block 112 before cutting the polymer-infiltrated graphene fiber block 112.
[0045] Although the present invention has been described with reference to its specific exemplary embodiments, many different alternatives, modifications, etc. will be apparent to those skilled in the art. In addition, it should be noted that the method part can be omitted, interchanged, or arranged in various ways, and the method can still perform the functions of the present invention.
[0046] In addition, by studying the drawings, the disclosure and the appended claims, those skilled in the art can understand and implement variations of the disclosed embodiments when practicing the claimed invention. In the claims, the word "comprising" does not exclude other elements or steps, and the indefinite article "a" or "an" does not exclude a plurality. The fact that certain measures are recited in mutually different dependent claims does not mean that a combination of these measures cannot be used.
Claims
1. A method of manufacturing a thermal interface film, the method comprising: providing (200) a template (100) that includes a plurality of openings (102) therethrough; setting (202) graphene fibers (104) through the openings; attaching (204) a support plate (106) to at least one side (108) of the template such that the graphene fibers are attached to the support plate; removing (206) the template to expose the graphene fibers; permeating (208) the graphene fibers with a polymer material (110) to form a polymer-permeated graphene fiber mass (112); cutting (210) the polymer-permeated graphene fiber mass along a direction perpendicular to the extension of the graphene fibers to form a thermal interface film (114).
2. The method according to claim 1, the method further comprising: flattening the top surface (116) of the polymer-permeated graphene fiber mass before cutting the polymer-permeated graphene fiber mass.
3. The method according to claim 1 or 2, wherein, removing the template includes: etching away the template.
4. The method according to any one of the preceding claims, wherein, the template is made of a plastic material.
5. The method according to any one of the preceding claims, wherein, the template is made of polyethylene or polypropylene.
6. The method according to any one of claims 1 to 3, wherein, the template is made of alumina.
7. The method according to any one of the preceding claims, wherein, the support plate is made of metal.
8. The method according to any one of the preceding claims, wherein, attaching to the support plate includes: adhesively bonding the plate to the template and the graphene fibers.
9. The method according to claim 8, wherein, adhesively bonding the plate to the template and the graphene fibers includes using an epoxy-based glue.
10. The method according to any one of the preceding claims, the method further comprising: setting a mold (120) around the template, the mold including solid walls to contain the polymer material.
11. The method according to any one of the preceding claims, wherein, setting the graphene fibers through the openings includes: stitching the fibers.
12. The method according to any one of the preceding claims, the method further comprising: weaving and / or twisting the graphene fibers before setting the graphene fibers in the openings.
13. The method according to any one of the preceding claims, the method further comprising: attaching the support plate to two opposite sides of the template.
14. A thermal interface film (114), the thermal interface film comprising: a plurality of region portions composed of polymer-permeated graphene fibers (104), wherein the graphene fibers extend in a direction perpendicular to the plane of the film; and wherein the plurality of region portions of the polymer-permeated graphene fibers are surrounded by a polymer material (110).
15. The thermal interface film according to claim 14, wherein, the film has a thermal conductivity in the direction perpendicular to the plane of the film of 10 W / mK to 200 W / mK.
16. The thermal interface film according to claim 14 or 15, wherein, the amount of graphene fibers in the thermal interface film is 5 vol% to 90 vol%.
17. The thermal interface film according to any one of claims 14 to 15, wherein, the graphene fibers permeated by the polymer include continuous graphene fibers extending from the top surface to the bottom surface of the thermal interface film.
18. The thermal interface film according to any one of claims 14 to 17, wherein, the graphene fibers permeated by the polymer include woven graphene fibers.
19. The thermal interface film according to any one of claims 14 to 18, wherein, the graphene fibers permeated by the polymer include twisted graphene fibers.
20. The thermal interface film according to any one of claims 14 to 19, wherein, the graphene fibers permeated by the polymer include graphene fibers reinforced by graphene sheets.