Method for manufacturing a heat-conducting sheet

Abstract

The present application provides a manufacturing method of a heat conducting sheet, in particular to a manufacturing technology of a heat conducting sheet with improved orientation of carbon fibers arranged inside for heat conductivity and flexibility and with uniform distribution of heat conductivity coefficient, the manufacturing method comprising: a first step, continuously moving a film and carbon fiber filaments in a state of arranging the carbon fiber filaments on the film at a prescribed interval along a length direction; a second step, manufacturing a primary molding product through a coating process by spraying a coating liquid to the moving film and carbon fiber filaments and a process of curing at a temperature of 80-150℃; a third step, manufacturing a secondary molding product by cutting the primary molding product at a prescribed length; a fourth step, stacking the secondary molding products up and down at a required height; a fifth step, pressing the stacked secondary molding products along the up and down direction; and a sixth step, cutting the stacked secondary molding products at a prescribed size along a vertical direction.

Description

Technical Field

[0001] This invention relates to a method for manufacturing a heat-conducting sheet, specifically to a heat-conducting sheet manufacturing technology that improves the orientation of internally disposed carbon fibers and has a uniform thermal conductivity distribution in order to improve thermal conductivity and flexibility. Background Technology

[0002] Recently, with the increasing performance of electronic devices, there is a trend towards higher density and more advanced mounting of semiconductor devices. Ultimately, effective heat dissipation from electronic components has become crucial. To achieve effective heat dissipation, semiconductor devices utilize heat sinks such as thermal pads or heat dissipation plates. As thermal pads, fillers (thermally conductive fillers) containing inorganic fillers dispersed in silicon are widely used. Examples of such inorganic fillers include alumina, aluminum nitride, and aluminum hydroxide.

[0003] There have been several attempts to manufacture such heat-conducting sheets, one of which is disclosed as prior art in Patent Publication No. 10-2016-0013270. In the prior art, a basic molded material is obtained by extruding a thermally conductive composition containing binders, carbon fibers, and inorganic fillers, and then the heat-conducting sheet is manufactured through a series of processes such as extrusion, molding, curing, and cutting (slicing).

[0004] On the other hand, lamination techniques for bonding stacked sheets generally include: 1) Adhesive lamination; 2) Hot melt lamination. Adhesive lamination is the most common method, which uses an adhesive to bond multiple layers together. After uniformly applying the adhesive, heat and pressure are applied to cure the adhesive and form a strong bond. Furthermore, 2) Hot melt lamination utilizes the melting properties of the material itself and bonds the layers together through heat and pressure. The material is heated to a temperature above its melting point and softened, then stacked into multiple layers. Pressure is applied to allow the molten material to diffuse and bond together.

[0005] However, the average fiber length (average major axis length) of the carbon fibers placed into the thermally conductive components of the prior art is 50 μm to 250 μm, preferably 75 μm to 200 μm, and carbon fibers of 100 μm to 150 μm are placed. When extruding with such carbon fibers, the following problems exist.

[0006] Carbon fiber is a material that forms its length along its long axis. When it is randomly mixed with thermally conductive components and extruded, there is a problem that the carbon fiber cannot be configured with its length direction along a specified direction and is randomly oriented.

[0007] Therefore, it is difficult to achieve a uniform thermal conductivity distribution in the heat-conducting sheet, and it is also impossible to control the degree of carbon fiber distribution inside the heat-conducting sheet, which makes it difficult to adjust the thermal conductivity.

[0008] Furthermore, with the use of extrusion processes, the size of existing thermal conductive sheet products is limited by the size of the basic equipment, thus making it impossible to manufacture large-area thermal conductive sheets.

[0009] Existing technical documents

[0010] Patent documents

[0011] Patent Document 1: Publication No. 10-2016-0013270: Thermal conductive sheet and its manufacturing method and semiconductor device

[0012] Patent Document 2: Korean Patent 10-2561334

[0013] Patent Document 3: Korean Patent No. 10-0453588

[0014] Patent Document 4: Korean Patent 10-1242384 Summary of the Invention

[0015] Technical issues

[0016] The purpose of this invention is to provide a method for manufacturing a heat-conducting sheet in which carbon fibers are arranged in an oriented manner.

[0017] Furthermore, the present invention provides a manufacturing method that achieves the desired thermal conductivity effect of the sheet by arranging carbon fibers at uniform intervals inside the thermally conductive sheet, thereby achieving uniform thermal conductivity and allowing the spacing of the carbon fibers to be adjusted.

[0018] Furthermore, the present invention provides a manufacturing method for producing products of various sizes and large-area heat-conducting sheets by overcoming the limitations of existing extrusion processes.

[0019] Technical solution

[0020] This invention relates to a manufacturing technology for a heat-conducting sheet that improves the orientation of internally disposed carbon fibers and achieves a uniform thermal conductivity distribution for enhanced thermal conductivity and flexibility. The specific steps include: a first step of continuously moving the film and carbon fiber yarns while arranging them on a film at predetermined intervals along its length; a second step of coating the film and carbon fiber yarns by spraying a coating liquid onto them and then curing them at a temperature of 80–150°C to produce a primary molded product; a third step of cutting the primary molded product to a predetermined length to produce a secondary molded product; a fourth step of stacking the secondary molded products vertically to a desired height; a fifth step of applying pressure to the stacked secondary molded products along the vertical direction; and a sixth step of cutting the stacked secondary molded products to a predetermined size along the vertical direction. Spraying the coating liquid onto the film and carbon fiber yarns can be achieved using various methods such as roll coating, comma coating, and spin coating.

[0021] The pressurization in the fifth step can be performed under vacuum to remove air bubbles between the upper and lower stacked secondary molded products and improve adhesion. The thickness of the film is 25-250 μm, the diameter of the carbon fiber precursor is 5-20 μm, and the thermal conductivity is 100-1200 W / mK. In the second step, the thickness of the coating is 5-300 μm.

[0022] The film can be selected from PET, PE, PP, and PI, and the coating liquid can be selected from silicone, acrylic, and polyurethane coating liquids.

[0023] The effects of the invention

[0024] The present invention provides a heat-conducting sheet manufactured through the aforementioned process, which has the advantages of directional and constant and uniform distribution of carbon fibers distributed inside, ultimately enabling the heat-conducting sheet to achieve a uniform heat conduction distribution.

[0025] Furthermore, since the present invention allows carbon fibers to be disposed on a thin film, the spacing between the disposed carbon fibers can be adjusted, thereby achieving the advantageous effect of different thermal conductivity coefficients depending on the region of the sheet.

[0026] Furthermore, unlike existing basic processes, it can achieve the effect of manufacturing large-area heat-conducting sheets regardless of the size of the sheets produced. Attached Figure Description

[0027] Figures 1 to 3 A schematic diagram illustrating the process flow for manufacturing a thermally conductive sheet that improves the orientation of carbon fibers according to the present invention is shown. Detailed Implementation

[0028] The objects, specific advantages, and novel benefits of the invention will become more apparent from the following detailed description and preferred embodiments in conjunction with the accompanying drawings. Furthermore, the terminology used is defined after taking into account the functions of the invention, and may vary depending on the intent or convention of the user, application personnel, or others. Therefore, these terms should be defined based on the entire contents of this specification.

[0029] Furthermore, in describing the structural elements of the present invention, different reference numerals may be assigned to structural elements with the same name based on the accompanying drawings. Even in different drawings, structural elements with the same name may be assigned the same reference numerals. However, even in this case, it does not mean that the corresponding structural elements have different functions according to the embodiments or have the same functions in different embodiments. The function of each structural element should be determined based on the description of each structural element in the corresponding embodiments.

[0030] Furthermore, unless otherwise explicitly defined in this specification, the technical terms used herein should be interpreted in the sense that they are commonly understood by one of ordinary skill in the art to which this invention pertains, and should not be interpreted as overly general or overly narrow. Moreover, unless otherwise explicitly stated in the context, singular expressions used herein include plural expressions.

[0031] Figures 1 to 3 A schematic diagram illustrating the process flow for manufacturing a thermally conductive sheet that improves the orientation of carbon fibers according to the present invention is shown. Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

[0032] According to the present invention, a method for manufacturing a heat-conducting sheet will be described.

[0033] This invention relates to a manufacturing technique for a heat-conducting sheet that improves the orientation of internally disposed carbon fibers and has a uniform distribution of thermal conductivity in order to enhance thermal conductivity and flexibility.

[0034] As shown in the figure, the present invention is achieved through steps 1 to 6, including: a first step, in which carbon fiber filaments (carbon fiber yarns) are arranged at specified intervals along the length direction, and the film and carbon fiber filaments are continuously moved; a second step, in which a coating process is performed by spraying a coating liquid onto the moving film and carbon fiber filaments, and a process of curing at a temperature of 80-150°C is performed to manufacture a primary molded product; a third step, in which the primary molded product is cut to a specified length to produce a secondary molded product; a fourth step, in which the secondary molded products are stacked vertically to a required height; a fifth step, in which the stacked secondary molded products are pressurized along the vertical direction; and a sixth step, in which the stacked secondary molded products are cut vertically to a specified size. The coating liquid can be sprayed onto the film and carbon fiber filaments using various methods such as roll coating, comma coating, and spray coating.

[0035] Preferably, the pressurization in the fifth step is performed under vacuum to remove air bubbles between the upper and lower stacked secondary molded products and improve their adhesion. The pressurization force is 1 to 10 kgf, and the pressurization is performed from the top for a specified time.

[0036] Preferably, the thickness of the film is 25-250 μm, the diameter of the carbon fiber precursor is 5-20 μm, the thermal conductivity is 100-1200 W / mK, and in the second step, the thickness of the coating is 5-300 μm.

[0037] The film can be any type of film, including PET, PE, PP, PI, and Matte film, and can be selected from among them. Custom-shaped coatings can be used as needed. The coating liquid can be thermosetting or UV-curable, such as silicone, acrylic, or polyurethane, and may include fillers with excellent electrical and thermal conductivity. The curing equipment used for curing and fixing can include IR, NIR, UV, hot air, etc., with a suitable curing temperature of 80–150 degrees Celsius.

[0038] The carbon fibers used as the carbon fiber precursor are not particularly limited and can be appropriately selected according to the purpose. For example, they can be synthesized using pitch-based, PAN-based, arc discharge, laser evaporation, CVD (chemical vapor deposition), CCVD (catalyst-based chemical vapor deposition), etc.

[0039] This invention relates to a heat-conducting sheet manufactured through the aforementioned process, which has the advantages of ensuring the directionality and uniform distribution of the carbon fibers distributed within it. Ultimately, the heat-conducting sheet can achieve a uniform thermal conductivity distribution and a relatively high thermal conductivity. Furthermore, unlike existing basic processes, large-area heat-conducting sheets can be manufactured without being limited by the size of the sheet produced.

[0040] Furthermore, in this invention, since carbon fibers are disposed on the thin film, the spacing between the carbon fibers can be adjusted, thereby achieving different thermal conductivity coefficients depending on the region of the sheet. In other words, by making the density of carbon fibers distributed in a part of the heat-conducting sheet different from the density of carbon fibers distributed in other areas, the thermal conductivity of a part of the heat-conducting sheet can be made different from that of other areas.

[0041] The preferred embodiments of the present invention have been described in detail above, but the scope of the present invention is not limited thereto. Various modified and improved embodiments implemented by those skilled in the art based on the basic concepts of the present invention as defined in the appended claims are also within the scope of the present invention.

Claims

1. A method for manufacturing a heat-conducting sheet, characterized in that, include: The first step involves continuously moving the film and the carbon fiber filaments while the carbon fiber yarns are arranged at specified intervals along the length direction. The second step involves coating the film and carbon fiber precursor by spraying a coating liquid onto them and curing them at a temperature of 80–150°C to produce a one-piece molded product. The third step is to produce a secondary molded product by cutting the primary molded product to a specified length. The fourth step is to stack the secondary molded products one on top of the other to the required height. The fifth step is to apply pressure to the stacked secondary molded products along the vertical direction; as well as The sixth step is to cut the stacked secondary molded articles vertically to the specified size.

2. The method for manufacturing a heat-conducting sheet according to claim 1, characterized in that, The pressurization in the fifth step is performed under vacuum to remove air bubbles between the upper and lower stacked secondary molded products and improve their adhesion.

3. The method for manufacturing a heat-conducting sheet according to claim 1, characterized in that, The thickness of the film is 25–250 μm. The diameter of the carbon fiber precursor is 5–20 μm, and the thermal conductivity is 100–1200 W / mK. In the second step, the coating thickness is 5–300 μm.

4. The method for manufacturing a heat-conducting sheet according to claim 1, characterized in that, The film is selected from polyethylene terephthalate, polyethylene, polypropylene, and polyimide. The coating liquid is selected from silicone, acrylic, and polyurethane coating liquids.

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