Heat sinks for electronic devices

Abstract

To provide a heat sink for an electronic device.SOLUTION: A heat sink includes a base and a plurality of fins protruding from one side of the base. The base and fins are independently composed of one or more anisotropic heat conductive films. The anisotropic heat conductive film has a low Dk value and a low Df value, and has an electrical insulation property. A method of manufacturing a heat sink, and a method of dissipating heat from an electronic device that has at least one heat generating component are also disclosed.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a heat sink for heat dissipation in electronic devices, which is made of an anisotropic thermally conductive film. [Background technology]

[0002] Heat sinks are commonly used to increase the convection surface area of ​​heat-generating devices to improve heat dissipation. Traditional heat sinks are usually made of metals with high thermal conductivity, especially aluminum and copper. Although these metallic heat sinks efficiently dissipate heat, they still have drawbacks that limit their applications. One inherent problem is that metallic heat sinks are electrically conductive, making them unsuitable for electronic devices with high voltages or exposed circuitry. In addition, metallic heat sinks can interfere with electromagnetic signals and / or energy transmission, affecting the operation of some communication devices. Furthermore, the trend toward lighter electronic devices is also limiting the applications of metallic heat sinks.

[0003] Thermally conductive polymer composites are a good alternative to metals for heat sinks due to their low cost, light weight, moldability, flexibility, corrosion resistance, non-reactive stability, and electrical insulation. For example, in Patent Document 1, Akira Ito et al. disclose a heat sink comprising a molded body made of a thermoplastic resin composition containing (A) a thermoplastic resin, (B) a filler having a thermal conductivity of 5 W / m·K or more, and (C) rosin. As shown in Table 1 of Patent Document 1, in order to obtain a composite with a thermal conductivity improved from 5 W / m·K to 28 W / m·K, the amount of graphite added to the polyamide resin (PA6) must be increased from 33 wt% (Example 5) to 57 wt% (Example 8).

[0004] T.C. Tankala et al., in Patent Document 2, disclose a plastic heat sink system consisting of 35 to 80 volume % thermoplastic polymer and a combination of fillers with high or low thermal conductivity and electrical resistivity, including ZnS, CaO, MgO, ZnO, TiO2, AlN, BN, MgSiN2, SiC, ceramic-coated graphite, graphite, expanded graphite, graphene, carbon fiber, carbon nanotubes (CNTs), and graphitized carbon black.

[0005] However, commercially available thermally conductive polymers generally have a thermal conductivity of about 5 W / m K. Polymer composites that exhibit thermal conductivities higher than 5 W / m K may have high thermally conductive filler loadings of at least 30 wt %, which typically compromises the benefits of the polymer composite, resulting in, for example, higher density, reduced mechanical properties, and increased difficulties in moldability and processability. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2014-093427 [Patent Document 2] US Patent Application Publication No. 2012 / 0307501A1 Summary of the Invention [Means for solving the problem]

[0007] The present invention provides a heat sink for an electronic device, comprising a base portion and a plurality of fins protruding from one surface of the base portion, The base portion has a length (L1) in the range of 5 mm to 300 mm, a width (W1) in the range of 5 mm to 300 mm, and a thickness (H1) in the range of 0.03 mm to 200 mm; Each fin has a thickness (L2) of less than 2.0 mm, a width (W2) in the range of 0.5 to 2.0 times W1, and a protruding height (H2) of at least 3 mm; The average number of fins ranges from 0.5 to 10 per 10 mm of base length. the base portion is comprised of one or more first polymer films; each fin comprising one or more second polymer films; The first polymer film and the second polymer film are anisotropic thermally conductive films, and each independently has a thickness of 10 15 It has a volume resistivity exceeding Ω cm, an in-plane thermal conductivity in one direction that is higher than the in-plane thermal conductivity in the orthogonal direction, said high thermal conductivity being in the range of 10 to 100 W / m K, a dielectric constant (Dk) at 30 GHz of 4 or less, and a dielectric dissipation factor (Df) at 30 GHz of 0.001 or less, The first polymer film and the second polymer film provide a heat sink, provided that they do not contain a filler having a thermal conductivity of 5 W / m·K or greater.

[0008] In one embodiment of the heat sink of the present invention, the first polymer film and the second polymer film each independently have a crystallinity of at least 75%.

[0009] In another embodiment of the heat sink of the present invention, the first polymer film and the second polymer film are each independently composed of a polymer having an average molecular weight that is at least 1,000,000.

[0010] In yet another embodiment of the heat sink of the present invention, the first polymer film and the second polymer film are each independently composed of a polymer selected from the group consisting of polyethylene (PE), polytetrafluoroethylene (PTFE), poly(p-phenylenebenzobisoxazole) (PBO), polyhydroquinone-diimidazopyridine (PIPD), and poly(phenylenebenzobisthiazole) (PBZT).

[0011] In yet another embodiment of the heat sink of the present invention, the first polymer film and the second polymer film are the same.

[0012] In one embodiment of the heat sink of the present invention, the fins and base are separate pieces that are assembled together by laser soldering, gluing, inserting, stitching, or a combination thereof.

[0013] In another embodiment of the heat sink of the present invention, the surface of the base is flat and textured with a plurality of slots or slits, each slot having a shape or 3D shape that matches the connecting portion of the fin.

[0014] In yet another embodiment of the heat sink of the present invention, a portion of each fin is connected to the base and is flat, wedge-shaped, curved, flanged, or shaped to conform to the 3D shape of the base.

[0015] In yet another embodiment of the heat sink of the present invention, each fin is a rectangular, square, circular, oval, hexagonal, or irregularly shaped sheet.

[0016] In a further embodiment of the heat sink of the present invention, each fin is a thin plate made up of a plurality of cells having a triangular, square, rectangular, circular, or hexagonal cross-sectional shape.

[0017] In one embodiment of the heat sink of the present invention, the fins are interconnected into a block having a plurality of air passages, each air passage having a triangular, square, rectangular, circular, or hexagonal cross-sectional shape.

[0018] In another embodiment of the heat sink of the present invention, the base portion is formed from a plurality of first polymer films by laminating, thermoforming, stitching, or a combination thereof, and optionally by applying an adhesive between adjacent polymer films.

[0019] In yet another embodiment of the heat sink of the present invention, the first polymer films are laminated with an orientation angle θ1 ranging from 0° to 90° between adjacent polymer films relative to their respective higher conduction directions.

[0020] In a further embodiment of the heat sink of the present invention, each fin is formed from a plurality of second polymer films by laminating, thermoforming, stitching, or a combination thereof, and optionally by applying an adhesive between adjacent polymer films.

[0021] In one embodiment of the heat sink of the present invention, the second polymer film is laminated with an orientation angle θ2 ranging from 0° to 90° between adjacent polymer films relative to their higher thermal conductivity direction.

[0022] The present invention also provides a method for manufacturing the heat sink of the present invention, a method for dissipating heat from an electronic device, and an electronic device comprising the heat sink of the present invention. [Brief explanation of the drawings]

[0023] [Figure 1] 1 is a perspective view showing an embodiment of the present invention. [Figure 2] 1A-1C are cross-sectional views illustrating some embodiments of the present invention. [Figure 3] 1 is a perspective view illustrating some embodiments of the present invention. [Figure 4] 1 shows stacks formed by laminating at different orientation angles of 0° or 90°. The higher thermal conductivity direction of each anisotropic thermally conductive film and the stacks made therefrom is represented by black arrows. [Figure 5] FIG. 5(A) is a perspective view illustrating one embodiment of a method for manufacturing a heat sink of the present invention, and FIG. 5(B) is a side view of the resulting heat sink. [Figure 6] 1A-1C illustrate some embodiments of the present invention in which rectangular shaped fins are formed by folding strips of anisotropic thermally conductive film or laminates made therefrom. [Figure 7] 10A-10C illustrate some embodiments of the present invention in which the looped fins are formed by folding strips of anisotropic thermally conductive film or laminates made therefrom. [Figure 8] 1 is a perspective view illustrating one embodiment of the method of the present invention for heat dissipation in an electronic device. [Figure 9] FIG. 10 is a perspective view showing a thermal resistor assembly for testing the heat removal performance of each heat sink sample. DETAILED DESCRIPTION OF THE INVENTION

[0024] Those skilled in the art will appreciate that objects in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions of some of the objects in the figures may be exaggerated relative to other objects to help improve understanding of the embodiments.

[0025] All publications, patent applications, patents, and other references mentioned herein are expressly incorporated herein by reference in their entirety for all purposes as if fully set forth, unless otherwise noted. 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 invention belongs. In case of conflict, the present specification, including definitions, will control.

[0026] Unless otherwise specified, all percentages, parts, ratios, etc. are by weight.

[0027] As used herein, the term "made from" is synonymous with "comprising." As used herein, the terms "comprise," "including," "include," "including," "having," "having," "containing," or "containing," or any other variation thereof, are intended to cover a non-exclusive inclusion. For example, a composition, process, method, article, or device that includes a list of elements is not necessarily limited to only those elements and may include other elements not expressly listed or inherent to such composition, process, method, article, or device.

[0028] The transitional phrase "consisting of" excludes any element, step, or ingredient not specified. When in a claim, such a phrase excludes from the claim the inclusion of materials other than those recited, except for impurities ordinarily associated therewith. When the phrase "consisting of" appears in a clause in the body of a claim, rather than immediately following a preamble, it limits only the elements recited in that clause and does not exclude other elements from the claim as a whole.

[0029] The transitional phrase "consisting essentially of" is used to define a composition, method, or apparatus that includes materials, steps, features, components, or elements in addition to those literally contemplated, provided that these additional materials, steps, features, components, or elements do not materially affect the basic and novel characteristics of the claimed invention. The term "consisting essentially of" occupies a middle ground between "comprising" and "consisting of."

[0030] The term "comprising" is intended to include embodiments encompassed by the terms "consisting essentially of" and "consisting of." Similarly, the term "consisting essentially of" is intended to include embodiments encompassed by the term "consisting of."

[0031] When an amount, concentration, or other value or parameter is given as either a range, a preferred range, or a list of upper and lower preferred values, this should be understood to specifically disclose all ranges formed from any pairing of any upper range limit or preferred value with any lower range limit or preferred value, whether or not the ranges are individually disclosed. For example, if a range of "1 to 5" is given, the given range should be interpreted as including "1 to 4," "1 to 3," "1 to 2," "1 to 2 and 4 to 5," "1 to 3 and 5," etc. When a range of numerical values ​​is recited herein, unless otherwise specified, the range is intended to include its endpoints, and all integers and fractions within the range.

[0032] When the term "about" is used to describe a value or an endpoint of a range, the disclosure should be understood to include the specific value or endpoint referred to.

[0033] Furthermore, unless expressly stated to the contrary, "or" means an inclusive "or" and not an exclusive "or." For example, a condition A "or" B is satisfied by any one of the following: A is true (or exists) and B is false (or does not exist), A is false (or does not exist) and B is true (or exists), and A and B are both true (or exist).

[0034] As used herein, the terms "a" and "an" include the concepts of "at least one" and "one, two or more."

[0035] While numerous aspects and embodiments have been described above, these have been illustrative only and not limiting. After reading this specification, those skilled in the art will appreciate that other aspects and embodiments are possible without departing from the scope of the invention. Other features and advantages of the invention will be apparent from the following detailed description and claims.

[0036] heat sink Referring to FIG. 1, disclosed herein is a heat sink 100 comprising a base portion 110 and a plurality of fins 120 protruding from one side (i.e., the top surface) of the base portion, where the base portion has a length (L1), a width (W1), and a thickness (H1), and each fin has a thickness (L2), a width (W2), and a protruding height (H2) measured from the top surface of the base portion.

[0037] The preferred dimensions of the base are a length (L1) in the range of 5 mm to 300 mm, a width (W1) in the range of 5 mm to 300 mm, and a thickness (H1) in the range of 0.03 mm to 200 mm. The preferred dimensions of each fin are a thickness (L2) of 2.0 mm or less, or 0.03 mm to 1.5 mm, or 0.05 mm to 1.0 mm, a width (W2) of 0.5 to 2.0 times W1, or 0.7 to 1.5 times W1, or approximately the same as W1, and a protruding height (H2) of 3 mm or more, or 5 mm or more, or 10 mm or more. The number of fins is adjustable, and generally ranges from 0.5 to 10 fins per 10 mm of base length (L1) to ensure sufficient airflow between the fins.

[0038] The heat sink of the present invention may be formed by separate portions of a base and multiple fins, which may be assembled together by laser soldering, adhesive bonding, insertion, stitching, or a combination thereof. The heat sink of the present invention may have various configurations. For example, the surface of the base may be flat, as shown in Figures 2(A) and 2(B), or may have a textured shape with multiple slots cut out to match the connecting portions of the fins, as shown in Figures 2(C) and 2(D). The connecting portions of the fins may be flat, wedge-shaped, curved, or have flanges (see Figure 2(B)). In addition, as shown in Figures 2(E) and 2(F), the base may have slits cut into it, and the fins may be formed by passing a strip of thermally conductive film or a laminate made therefrom through the slits in the base (see Figure 2(F)). Alternatively, the base and fins can be created by folding a strip of thermally conductive film or a laminate made therefrom, without being attached to a separate base, as long as the strip has sufficient rigidity to maintain the configuration (see Figures 2(G) and (H)). Alternatively, they can be created by cutting a laminate block made of thermally conductive film, as shown in Figure 5(B), or by forming the base into a 3D shape and the fins have a shape that matches the 3D shape of the base. Heat sinks created by folding without a separate base can be attached to adhesive tape with a release film / paper. The release film / paper can be removed when the heat sink is ready to use to allow for good attachment to heat-generating components in electronic devices.

[0039] In the heat sink of the present invention, each fin may be a sheet having a square, rectangular, circular, oval, hexagonal, or irregular shape when viewed in the width direction, as shown in Figure 3(A). In the heat sink of the present invention, each fin may also be a thin plate composed of multiple cells having a triangular, square, rectangular, circular, or hexagonal cross-sectional shape (Figure 3(B)). Furthermore, the fins may be interconnected to form a heat dissipation block having multiple air passages along the width direction, and each air passage may have a triangular, square, rectangular, circular, or hexagonal cross-sectional shape (Figure 3(C)).

[0040] Those skilled in the art will have no difficulty in selecting an appropriate shape of the fins and design of the connecting portion depending on the particular application and the space allowed for the heat sink within the electronic device.

[0041] In the heat sink of the present invention, the base is composed of at least one layer of a first polymer film, and the fin is composed of at least one layer of a second polymer film. Both the first polymer film and the second polymer film are anisotropic thermally conductive films. As used herein, the terms "thermal conductivity" and "thermal conductivity" may be abbreviated as "TC," e.g., "thermally conductive film" may be abbreviated as "TC film," and "higher thermal conductivity direction" may be abbreviated as "higher TC direction." Each polymer film independently has a higher in-plane TC in one direction than in the orthogonal direction. The through-plane thermal conductivity of the polymer film is generally low, less than 1 W / m·K, or less than 0.5 W / m·K. Details of the first and second polymer films are described below.

[0042] Depending on the thickness of the first polymer films, the base portion may be formed from multiple first polymer films by laminating, thermoforming, stitching, or a combination thereof, optionally by applying adhesive between adjacent polymer films. The first polymer films may be laminated with an orientation angle θ1 ranging from 0° to 90° between adjacent polymer films relative to their higher TC direction, as represented by the black arrows in FIG. 4. The orientation angle θ1 may be an integer between 0° and 90°, such as 30°, 45°, or 60°, and is preferably 0° or 90° for better overall TC performance and / or maximum use of TC film without waste. The resulting base portion may have higher in-plane thermal conductivity in either one direction (unidirectional) or both the length and width directions.

[0043] Depending on the thickness of the second polymer film, each fin may be formed from multiple second polymer films by lamination, thermoforming, stitching, or a combination thereof, optionally with adhesive applied between adjacent polymer thin films. The second polymer films are laminated with an orientation angle θ2 ranging from 0° to 90° between adjacent polymer films relative to their higher TC direction. The orientation angle θ2 is also preferably 0° or 90° for the reasons described above.

[0044] First and second polymer films Polymers are known to have thermal conductivities of less than 1 W / m·K. However, oriented polymer fibers or films with high crystallinity and chain orientation tend to have higher thermal conductivities. Thermal energy in polymers can be transported along covalently bonded polymer chains, and for oriented polymers, thermal conductivity depends on many factors, including crystallinity, molecular weight, and molecular weight distribution.

[0045] The first and second polymer films are fabricated so that the polymer chains are substantially aligned to obtain anisotropic thermal conductivity. These anisotropic thermally conductive films have a higher thermal conductivity in one direction than in the orthogonal direction, the higher thermal conductivity ranging from about 10 W / m·K to about 100 W / m·K, or from about 20 W / m·K to about 80 W / m·K, or from about 30 W / m·K to about 60 W / m·K.

[0046] It should be noted that many known anisotropic thermally conductive films may incorporate thermally conductive fillers, such as graphite or boron nitride, to enhance in-plane thermal conductivity (up to 400 W / m·K). However, the preferred anisotropic thermally conductive films used in the heat sinks of the present invention do not contain fillers with thermal conductivities of 5 W / m·K or greater, so that the mechanical and electrical properties of the first and second polymer films are not compromised. Examples of thermally conductive fillers include talc, alumina oxide, ZnO, MgCO₃, ZnS, CaO, MgO, ZnO, TiO₂, AlN, BN, MgSiN₂, SiC, SiN, graphite, expanded graphite, ceramic-coated graphite, graphene, carbon fiber, carbon nanotubes (CNTs), graphitized carbon black, carbon black, and fullerenes.

[0047] Considering that the heat sink of the present invention may have application for electronic devices / components that transmit and receive high frequency and / or high speed signals, the first polymer film and the second polymer film preferably have excellent electrical properties, including high resistivity and low signal loss. 15 Preferably, the first polymer film and the second polymer film each independently have a dielectric constant (Dk) of 4 or less, or 3.2 or less, or 2.8 or less, or 2.5 or less at 10 GHz, or 20 GHz, or 30 GHz, and a dissipation factor (Df) of 0.001 or less, or 0.0005 or less, or 0.0003 or less at 10 GHz, or 20 GHz, or 30 GHz.

[0048] Oriented polymer films may be produced by heating a precursor film and stretching it multiple times along one direction (i.e., unidirectionally) at draw ratios of 5 to 100 or more. Alternative methods include extrusion, spin coating, injection molding, solid-state extrusion, electrospinning, etc. The polymer films formed as a result of the foregoing processes have improved in-plane thermal conductivity in the direction of stretching and are generally highly crystalline.

[0049] In some embodiments of the heat sink of the present invention, the first polymer film and the second polymer film each independently have a crystallinity of at least 75%, or at least 80%, or at least 85%, or at least 90%.

[0050] Since thermal energy is transported along aligned polymer chains, longer chain lengths are preferred. Therefore, polymers suitable for forming anisotropic thermally conductive films have very high molecular weights, with average molecular weights of at least 1,000,000 g / mol, or at least 2,000,000 g / mol, and preferably no more than 20 million g / mol.

[0051] The first and second polymer films suitable for use herein are each independently composed of a polymer selected from the group consisting of polyethylene (PE), polytetrafluoroethylene (PTFE), poly(p-phenylenebenzobisoxazole) (PBO), polyhydroquinone-diimidazopyridine (PIPD), and poly(phenylene)benzobisthiazole (PBZT).

[0052] Considering ease of manufacturing and raw material management, it is preferable that the first and second polymer films are identical. Those skilled in the art can prepare oriented polymer films according to well-known literature methods or by purchasing commercially available products. Commercially available products generally provide anisotropic TC polymer materials in the form of fibers. Unidirectional laminates composed of fibers may also be used as the first and second polymer films. Commercially available examples include, but are not limited to, Dyneema® (i.e., UHMWPE fiber / UD laminate) manufactured by DSM, Zylon® HM (i.e., PBO fiber) manufactured by Toyobo, and M5 AS (i.e., PIPD fiber) manufactured by AkzoNobel.

[0053] Considering the commercial availability of anisotropic films, the first and second polymer films are preferably composed of polyethylene having an average molecular weight of at least 1,000,000 g / mol. Such polyethylene is also known as ultra-high molecular weight polyethylene (UHMWPE). Suitable UHMWPE film thicknesses range from about 10 to about 360 μm, or from about 25 to about 250 μm, or from about 50 to about 200 μm.

[0054] Thermally conductive PE films are commercially available from EI du Pont de Nemours and Company (USA) (hereinafter referred to as "DuPont") under the trade name Temprion™ OHS with different thicknesses, and from Teijin under the trade name Endumax™ film TA23 with a thickness of 55 μm.

[0055] Method for manufacturing a heat sink As previously mentioned, the present invention also provides a method for manufacturing a heat sink of the present invention, comprising the steps of: (i) providing a base and a plurality of fins; (ii) assembling the fins onto the base by laser soldering, gluing, inserting, stitching, or a combination thereof; where: the base is comprised of one or more first polymer films; The surface of the base is flat and has a plurality of slots or slits, each slot having a shape or 3D shape that matches the connecting portion of the fin; each fin comprising one or more second polymer films; The method also provides that the connecting portion of each fin is flat, wedge-shaped, curved, flanged, or shaped to match the base of the 3D shape.

[0056] It should be noted that the fins are preferably arranged so that at least one of their high TC directions is perpendicular to the base, i.e., along the vertical direction of the heat sink, but the base may have one of its higher thermal conduction directions either vertical or horizontal to the heat sink.

[0057] Those skilled in the art can readily design and fabricate the heat sink of the present invention with a size, shape, and arrangement of fins on the base that are appropriately selected based on the location and characteristics of the heat-generating components of the electronic device. For example, a 3D-shaped base and matching fins may be fabricated by thermoforming using a mold. In general, the increased surface area provided by the heat sink can also improve convective / radiative heat transfer to the surrounding environment.

[0058] The heat sink of the present invention overcomes the drawbacks inherent in metallic heat sinks. Compared to heat sinks constructed with thermally conductive fillers containing polymers, the heat sink of the present invention exhibits improved heat removal efficiency with greater flexibility in design.

[0059] Use of a heat sink As previously mentioned, the present invention further provides a method for dissipating heat in an electronic device, comprising: (a) providing an electronic device having at least one heat-generating component; (b) placing the heat sink of the present invention on a heat-generating component, with the base portion in contact with or near the heat-generating component; (c) optionally applying a thermally conductive or heat resistant adhesive between the heat sink and the heat generating component.

[0060] The heat sink of the present invention may be used in electronic devices as a passive heat exchanger or may function as a thermal mass to absorb any amount of heat without significantly changing the temperature. Heat dissipation from the heat sink of the present invention may be achieved by convection or radiation to ambient or circulating airflow.

[0061] The electronic device may be, for example, a smartphone, a personal digital assistant (PDA), a digital video camera, a digital still camera, a network system, a computer, a monitor, a tablet PC, a laptop PC, a netbook PC, a television, a video game console, a smart watch, an automobile part, etc. However, the electronic device is not limited thereto and may be any other electronic device that processes data.

[0062] Electronic devices may generally include chip-related components, network-related components, other components, antenna modules, etc. Examples of chip-related components include memory chips such as volatile memory (e.g., dynamic random access memory (DRAM)), non-volatile memory (e.g., read-only memory (ROM)), and flash memory, central processing units (e.g., central processing units (CPUs)), graphics processors (e.g., graphics processing units (GPUs)), digital signal processors (DSPs), cryptographic processors, application processor chips such as microprocessors and microcontrollers, analog-to-digital (ADC) converters, and logic chips such as application specific integrated circuits (ASICs). Among these, application processor chips, including but not limited to CPUs, GPUs, and DSPs, are known to generate more heat than other electronic components, and the heat sink of the present invention is therefore suitable for dissipating the heat.

[0063] It should be noted that the surfaces of both the heat-generating component and the heat sink may have a non-planar interface, e.g., convex or concave. To ensure efficient cooling, a thin layer of thermally conductive or heat-resistant adhesive may be applied between the heat sink and the heat-generating component to fill the gap. The application of the thermally conductive or heat-resistant adhesive not only ensures efficient heat transfer but also firmly attaches the heat sink, so the electronic device may be a mobile device.

[0064] Referring to FIG. 8 , the heat sink 100 of the present invention is placed on a heat-generating component 810 that is part of a PCB 800. A thermally conductive or heat-resistant adhesive may be applied to the interface between the base portion 110 and the heat-generating component 810. The liquid thermally conductive or heat-resistant adhesive may be applied to the contact surfaces of the base portion 110 or the heat-generating component 810 by dispensing, stenciling, or spraying to form a thin layer having a thickness of up to 1.0 mm. The thermally conductive or heat-resistant adhesive may also be in the form of a film or tape, with or without a release film. Those skilled in the art can easily apply them using any common method or tool.

[0065] As disclosed herein, the present invention also relates to an electronic device comprising the heat sink of the present invention and obtained by the method described above.

[0066] In one embodiment of the electronic device of the present invention, the heat-generating component is an application processor chip for a central processing unit (CPU), a digital signal processor (DSP), or a graphics processing unit (GPU).

[0067] In another embodiment of the electronic device of the present invention, the heat generating component is not a light emitting diode (LED).

[0068] The following examples and comparative examples are provided to illustrate certain details of one or more embodiments, although it should be understood that embodiments of the present invention are not limited to the particular details described. [Example]

[0069] material: F1: Anisotropic TC film, commercially available from DuPont under the trade name TEMPRION™ OHS, with a film thickness of 60 μm, in-plane thermal conductivity of 45 W / m·K (longitudinal direction), 0.2 W / m·K (transverse direction), and through-plane thermal conductivity of 0.2 W / m·K, with Dk values ​​of 2.3 and 2.2, respectively, and Df values ​​of 0.00023 and 0.00022, respectively, at 10 GHz and 30 GHz. A two-layer laminate of F2:F1, in which the two films are stacked at an orientation angle of 90° to their higher thermal conduction direction, thus having an in-plane thermal conductivity of approximately 20 W / m·K in both the longitudinal and transverse directions. F3: A multilayer laminate of F1, consisting of four or more layers of F1, in which the orientation angle between adjacent films is 90°. In other words, each film is arranged by alternating with the direction of higher thermal conductivity perpendicular to the previously arranged film. F4: PET film with a thickness of 250 μm was purchased from Sunliky. Catalog number: NS2#250MPET. F5: 50 μm thick PET film was purchased from Sunliky. Catalog number: NS2#50MPET. F6: 110 μm thick PE film containing 13 wt% hexagonal boron nitride (h-BN). The PE film was fabricated by blending PE pellets (obtained from DOW, catalog number: XUS61850.00) with h-BN particles (purchased from the Dan Dong Institute of Chemical Engineering) and then extruding to form h-BN-containing pellets. The h-BN-containing pellets were hot-pressed at 140 °C to obtain an anisotropic TC film with an in-plane TC of 2.36 W / m·K (non-directional) and a through-plane TC of 0.30 W / m·K. Adh1: Heat-resistant acrylic adhesive, catalog number: ELG14010, purchased from Elegant. Adh2: Thermally conductive adhesive with a thermal conductivity of 0.6 W / m·K, catalog number: TB8005, purchased from Elegant.

[0070] Preparation of Example 1 As shown in Figure 5, a multilayer laminate (F3) having dimensions of 20 mm (L1) x 20 mm (W1) x 7 mm (i.e., H1 + H2) was cut using a water jet cutter to obtain a heat sink sample according to one embodiment of the present invention. The sample had 12 fins evenly spaced, with the spacing between two fins being approximately 1.0 mm. Each fin had a width of 20 mm (W2), a height of 5 mm (H2), and a fin thickness (L2) of 0.6 mm. The base of the resulting heat sink sample had its higher TC direction aligned with the vertical direction of the heat sink sample.

[0071] Preparation of Example 2 A multi-layer laminate (F3) measuring 20 mm (L1) × 20 mm (W1) × 2 mm (H1) was used as the base, with the higher heat conduction direction perpendicular to the heat sink sample. As shown in Figure 6, a rectangular strip of bi-layer laminate 610 (F2, measuring 20 mm × 120 mm) was folded to form eight fins, and the excess bi-layer laminate was then cut off. Each fin had a thickness (L2) of approximately 0.25 mm, a height (H2) of 5 mm, and a spacing between fins of approximately 2.5 mm. One piece of the folded fin was attached to a base 620 by applying a thin layer of adhesive (adh1) to form a heat sink sample having the configuration shown in Figure 2(A), which is one embodiment of the present invention.

[0072] Preparation of Example 3 A multi-layer laminate (F3) measuring 20 mm (L1) × 20 mm (W1) × 0.36 mm (H1) was used as the base, with the higher heat conduction direction aligned horizontally across the heat sink sample. Similar to the procedure described in Example 2, a rectangular strip of two-layer laminate (F2) (20 mm × 120 mm) was folded to form eight fins. Each fin had a thickness (L2) of approximately 0.25 mm, a height (H2) of 5 mm, and a spacing between fins of approximately 2.5 mm. The fins were then attached to the base by applying a thin layer of adhesive (adh1), and the excess material was trimmed to form a heat sink sample with the configuration shown in FIG. 2(A), which represents one embodiment of the present invention.

[0073] Preparation of Example 4 A multilayer laminate (F3) measuring 20 mm (L1) x 20 mm (W1) x 1 mm (H1) was used as the base, with the higher heat conduction direction aligned horizontally across the heat sink sample. The surface of the base was then scored with a knife to form eight 16 mm long slits. One piece of the two-layer laminate (F2) was cut into eight rectangular fins, each fin measuring 0.12 mm thick, 16 mm wide, and 6 mm high. Each fin was inserted into the slit on the base to assemble the heat sink sample, forming a heat sink sample with the configuration shown in Figure 2(E), which represents one embodiment of the present invention.

[0074] Preparation of Example 5 A multilayer laminate (F3) measuring 20 mm (L1) x 20 mm (W1) x 0.36 mm (H1) was used as the base, with the higher heat conduction direction aligned horizontally across the heat sink sample. Ten slits parallel to the width of the base were cut with a knife. Each slit was approximately 16 mm long, with a 2 mm spacing between each slit. Rectangular pieces of monolayer film (F1, 16 mm x 200 mm) were inserted alternately from the bottom and top into the slits in the base to form five loops as fins (each loop estimated to have a circumference of 36 mm and a height of approximately 17 mm). The heat sink sample was constructed as shown in Figure 2(F), which is one embodiment of the present invention.

[0075] Preparation of Example 6 As shown in FIG. 7, in one embodiment of the present invention, a rectangular piece of two-layer laminate 710 (F2, size: 20 mm x 380 mm) was folded to form nine loops, each with a circumference of 40 mm, with a spacing of approximately 2 mm between two loops and 2 mm from the edge of the base, and then adhered to a piece of adhesive tape 720 with a release film to form heat sink sample 700.

[0076] Preparation of Example 7 Similar to the procedure described in Example 2, a rectangular piece of two-layer laminate (F2, size: 20 mm × 380 mm) was folded to form nine fins, each 20 mm high (H2) and 0.25 mm thick (L2), with approximately 2 mm spacing between the fins, which were then adhered to a piece of adhesive tape with a release film to form a heat sink sample having the configuration shown in Figure 2(H), which is one embodiment of the present invention.

[0077] Preparation of Example 8 Following the procedure described in Example 2, a rectangular piece of two-layer laminate (F2, size: 20 mm × 150 mm) was folded to form nine fins, each 7 mm high (H2) and 0.25 mm thick (L2), with approximately 2 mm spacing between the fins, which were then adhered to a piece of adhesive tape to form a heat sink sample having the configuration shown in Figure 2(H), which is one embodiment of the present invention.

[0078] Preparation of Comparative Example 1 (CE1) Similar to the procedure described in Example 6, a rectangular piece of 50 μm PET film (F5, dimensions: 20 mm wide x 200 mm long x 0.05 mm high) was folded to form five loops as fins 710, with each loop having a circumference of 38 mm. A 250 μm PET film (F4) with dimensions of 20 mm (L1) x 20 mm (W1) x 0.25 mm (H1) was used as the base 720. The loops were then adhered to the base by applying a piece of adhesive tape to form a comparative heat sink sample (as shown in FIG. 7).

[0079] Preparation of Comparative Example 2 (CE2) A cast aluminum heat sink was purchased from Dongguan Haolong Hardware Products and used as a comparative example. The aluminum heat sink had a base measuring 20 mm (W1) × 20 mm (L1) × 2 mm (H1) and eight evenly spaced fins. Each fin measured 20 mm (W2) × 1 mm (L2) × 5 mm (H2).

[0080] Preparation of Comparative Example 3 (CE3) Similar to the procedure described in Example 8, a piece of rectangular film (F6, size: 20 mm × 150 mm) was folded to form nine fins with a height of 7 mm (H2) and a thickness of 0.22 mm (L2), with a spacing of approximately 2 mm between the fins, and then adhered to a piece of adhesive tape to form a heat sink sample having the configuration shown in Figure 2(H) as a comparative sample.

[0081] Test Method The heat dissipation performance evaluation was performed using a heating resistor assembly 900 as shown in Figure 9. A heating resistor 910 (8.5 mm × 10 mm × 4.5 mm, Model: TO220 35W, manufactured by Xinlong Electronics, with an adjustable DC power supply (not shown in Figure 9) (Cat. No. 30V5A, DP3005ET, manufactured by MESTEK) and a stainless steel heat spreader 920 (10 mm × 13 mm × 1 mm) were used to simulate an operating power chip. The heating resistor assembly (910 and 920) was attached to a thin aluminum plate 930 (20 mm × 20 mm × 0.8 mm) with a thermally conductive adhesive (adh2) with a thermal conductivity of 0.6 W / m K. A thermocouple 940 was attached with tape to the backside of the thin aluminum plate 930 to measure the temperature of the aluminum plate.

[0082] The heating resistor 910 had a power setting of 4 watts and was heated for approximately 10 minutes, resulting in the aluminum plate 930 reaching a stable temperature in 5 minutes as measured by the thermocouple 940. When no sample was placed on top of the aluminum plate, the steady-state temperature reading was recorded as T1 and used as the reference temperature. Then, as shown in FIG. 9, the heat sink sample 100 was placed on the heated aluminum plate, and the heat sink sample was allowed to dissipate heat until the temperature reading stabilized for 5 minutes and was recorded as T2. The difference between T1 and T2 (ΔT) determined the heat removal performance, and the data is listed in Table 1. The greater the degree of cooling, the better the heat removal performance.

[0083] Volume resistivity (Ω·cm): The volume resistivity of each material (10 cm × 10 cm) used to fabricate the heat sink was measured using a Keithley 6517A electrometer / high-resistance meter according to ASTM D257 method. The measurement data are listed in Table 1. The volume resistivity of aluminum was obtained from public information.

[0084] As is evident from the data in Table 1, the heat sink samples E1 to E8 of the present invention made from polymer films that did not contain a thermally conductive filler exhibited excellent heat removal performance with cooling degrees ranging from -11°C to -28°C.

[0085] Comparing E6 and CE1, both heat sink samples were constructed in the same manner and had similar fin heights (approximately 19 mm vs. approximately 18 mm), and the E6 sample demonstrated better heat removal performance at -25°C than the CE1 (i.e., +1°C). Note that the CE1 sample has more fins than the E6, and therefore a greater total surface area for heat dissipation. The CE1 sample is constructed of PET film without TC filler, and therefore is expected to have inferior heat removal performance.

[0086] Comparing E8 and CE3, both heat sink samples had the same configuration, fin count, and fin height, with only a slight difference in fin thickness. The E8 sample exhibited a heat rejection performance of -17°C, much better than that of CE3 (i.e., -3°C). Note that the CE3 sample was constructed of polyethylene containing 13 wt% h-BN. While increasing the TC filler content in the polymer film / matrix may improve heat rejection performance, heat sinks made from such high TC filler content materials are expected to have reduced mechanical properties and undesirably high Dk / Df values.

[0087] Furthermore, the heat sink samples E1, E2, E6, and E7 surprisingly exhibited heat removal performance (-31°C) close to that of the alumina heat sink sample CE2. The results suggest that the heat sinks of the present invention, composed of anisotropic thermally conductive films, may, through optimized design (e.g., fin number, fin height, and configuration), provide excellent heat removal performance similar to that of metallic heat sinks. Needless to say, the heat sinks of the present invention also possess excellent electronic properties, such as high resistivity, low Dk and Df values, and light weight, thus making them well suited for use in electronic devices for high-frequency and / or high-speed applications.

[0088] [Table 1] [Explanation of symbols]

[0089] 100 Heatsink 110, 620 base 120, 710 fins 610 2 layer laminate 700 Heat Sink Samples 720 adhesive tape 810 Heat-generating parts 900, 910, 920 Heating Resistor Assembly adh2 thermally conductive adhesive L1 length L2 thickness H2 Projection height H1 Thickness W1, W2 width

Claims

1. A heat sink for an electronic device, comprising: a base portion; and a plurality of fins protruding from one surface of the base portion, The base portion has a length (L1) in the range of 5 mm to 300 mm, a width (W1) in the range of 5 mm to 300 mm, and a thickness (H1) in the range of 0.03 mm to 200 mm; Each fin has a thickness (L2) of 2.0 mm or less, a width (W2) in the range of 0.5 to 2.0 times W1, and a protruding height (H2) of at least 3 mm; the average number of fins is in the range of 0.5 to 10 per 10 mm of length of the base portion; the base portion is comprised of one or more first polymer films; each fin comprising one or more second polymer films; The first polymer film and the second polymer film are anisotropic heat conductive films, and each independently 15 a volume resistivity exceeding Ω cm, an in-plane thermal conductivity in one direction higher than the in-plane thermal conductivity in the orthogonal direction, said high thermal conductivity being in the range of 10 to 100 W / m K, a dielectric constant at 30 GHz being 4 or less, and a dielectric dissipation factor at 30 GHz being 0.001 or less; the first polymer film and the second polymer film do not contain a filler having a thermal conductivity of 5 W / m·K or more; heat sink.

2. The heat sink of claim 1 , wherein the first polymer film and the second polymer film each independently have a crystallinity of at least 75%.

3. 10. The heat sink of claim 1, wherein the first polymer film and the second polymer film are each independently composed of a polymer having an average molecular weight that is at least 1,000,000 g / mol.

4. 2. The heat sink of claim 1, wherein the first polymer film and the second polymer film are each independently composed of a polymer selected from the group consisting of polyethylene, polytetrafluoroethylene, poly(p-phenylenebenzobisoxazole), polyhydroquinone-diimidazopyridine, and poly(phenylenebenzobisthiazole).

5. The heat sink of claim 1 , wherein the first polymer film and the second polymer film are the same.

6. The heat sink of claim 1 , wherein the fins and the base are separate pieces and assembled together by laser soldering, gluing, inserting, stitching, or a combination thereof.

7. The heat sink of claim 1 , wherein the surface of the base is flat and textured with a plurality of slots or slits, each slot having a shape or 3D shape that matches a connecting portion of the fin.

8. 10. The heat sink of claim 1, wherein a portion of each fin is connected to the base and is flat, wedge-shaped, curved, flanged, or shaped to conform to the 3D shape of the base.

9. The heat sink of claim 1 , wherein each fin is a square, rectangular, circular, oval, hexagonal, or irregularly shaped sheet.

10. The heat sink of claim 1 , wherein each fin is a thin plate made up of a plurality of cells having a triangular, square, rectangular, circular, or hexagonal cross-sectional shape.

11. The heat sink of claim 1 , wherein the fins are interconnected into a block having a plurality of air passages, each air passage having a triangular, square, rectangular, circular, or hexagonal cross-sectional shape.

12. The heat sink of claim 1 , wherein the base portion is formed from a plurality of the first polymer films by laminating, thermoforming, stitching, or a combination thereof.

13. A heat sink as described in claim 12, wherein the base portion is further formed from a plurality of the first polymer films by applying adhesive between adjacent polymer films.

14. The heat sink of claim 12, wherein the first polymer films are stacked with an orientation angle θ1 ranging from 0° to 90° between the adjacent polymer films relative to their respective higher thermal conduction directions.

15. The heat sink of claim 1 , wherein each fin is formed from a plurality of the second polymer films by laminating, thermoforming, stitching, or a combination thereof.

16. A heat sink as described in claim 15, wherein each fin is further formed from a plurality of the second polymer films by applying adhesive between adjacent polymer films.

17. The heat sink of claim 15, wherein the second polymer films are laminated at an orientation angle θ2 ranging from 0° to 90° between the adjacent polymer films relative to their respective higher thermal conduction directions.

18. 10. A method for manufacturing the heat sink of claim 1, comprising: (i) providing a base portion and a plurality of fins; (ii) assembling the fin onto the base by laser soldering, gluing, inserting, stitching, or a combination thereof; the base portion is comprised of one or more first polymer films; the surface of the base is flat and has a plurality of slots or slits, each slot having a shape or 3D shape that matches a connecting portion of the fin; each fin comprising one or more second polymer films; the connecting portion of each fin is flat, wedge-shaped, curved, flanged, or shaped to match the base of the 3D shape; method.

19. 1. A method for dissipating heat in an electronic device, comprising: (a) providing an electronic device having at least one heat-generating component; (b) placing the heat sink of claim 1 on the heat generating component, with the base portion of the heat sink in contact with or near the heat generating component; A method comprising:

20. (c) applying a thermally conductive adhesive or a heat-resistant adhesive between the base portion and the heat-generating component; 20. The method of claim 19 further comprising:

21. 10. An electronic device comprising: at least one heat-generating component; and a heat sink according to claim 1, wherein the heat sink is disposed on the heat-generating component, the base of the heat sink being in contact with or near the heat-generating component.

22. An electronic device as described in claim 21, further comprising a thermally conductive adhesive or a heat-resistant adhesive, the thermally conductive adhesive or the heat-resistant adhesive being positioned between the base portion and the heat-generating component.

23. 22. The electronic device of claim 21, wherein the heat-generating component is an application processor chip for a central processing unit, a digital signal processor, or a graphics processing unit.

24. 22. The electronic device of claim 21, wherein the heat generating component is not a light emitting diode.

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