Flexible Graphite Structure

Abstract

Disclosed is a flexible graphite structure that can be used as a heat dissipation sheet for flexible electronic devices using a graphite sheet unit that includes stretchable regions formed as cut regions or overlap regions. The disclosed flexible graphite structure includes a graphite sheet unit that includes a single graphite sheet layer or multiple graphite sheet layers having at least one stretchable region, and a stretchable sheet layer attached to at least one of both outermost surfaces of the graphite sheet unit and configured to cover the at least one stretchable region, where the at least one stretchable region is formed by providing at least a pair of cutout regions in the single graphite sheet layer or by providing overlap regions where the single graphite sheet layer or multiple graphite sheet layers overlap.

Description

[Technical field]

[0001] The present disclosure relates to a flexible graphite structure formed by using a graphite sheet unit including an elastic region formed by a cutout region or an overlap region as a heat dissipation layer and adhering an elastic sheet layer to at least one outermost surface of the graphite sheet unit to protect the graphite sheet unit. [Background technology]

[0002] As portable / mobile devices such as cameras, cell phones, mobile computers, and tablets have evolved over the decades, the needs and capabilities of these devices have also evolved. With each generation of devices, the devices have enabled users to create, modify, and distribute content from their devices, as well as provide more content to the device's users at ever higher bandwidths and in more user-friendly formats. As the convenience of these devices has increased, the power requirements of the devices have increased and the technology associated with the batteries of these devices has improved. Today's generation of devices contain more energy, generate more power, and therefore generate more heat. In addition to the batteries, the hardware products of the devices (e.g., radio units, displays, and processing units) have also become more robust, bringing additional heat issues to these devices as well.

[0003] In order to solve such heat problems, a technique has been devised for attaching a graphite sheet layer having high thermal conductivity to the heat generating portion of an electronic device. When a graphite sheet layer is attached to the back surface of a portion of an electronic device where a lot of heat is generated, the thermal conductivity of the graphite sheet layer in the planar direction is relatively large compared to the thermal conductivity of the graphite sheet layer in the thickness direction. Therefore, heat is efficiently diffused and transferred, and the heat generated in the electronic device is radiated to the outside through the graphite sheet layer.

[0004] In recent years, as the technology of portable devices / mobile devices has been further developed, devices equipped with various displays, such as bendable flexible displays and foldable displays that fold and unfold, have been developed. In order to dissipate heat from such devices, the flexibility of the heat dissipation sheet itself is required. However, the use of graphite sheets, which have excellent horizontal heat transfer properties, in flexible electronic devices has been limited due to their low flexibility. Summary of the Invention [Problem to be solved by the invention]

[0005] The present disclosure solves the problem that it is difficult to use a graphite sheet as a heat dissipation sheet in a flexible electronic device due to the low flexibility of the graphite sheet, and provides a flexible graphite structure that can be used as a heat dissipation sheet for a flexible electronic device by using a graphite sheet unit that includes an elastic region that includes a cutout region or an overlap region. [Means for solving the problem]

[0006] A flexible graphite structure according to one embodiment of the present disclosure includes a graphite sheet unit including a single graphite sheet layer or multiple graphite sheet layers having at least one elastic region, and an elastic sheet layer attached to at least one of the outermost surfaces of the graphite sheet unit and configured to cover the at least one elastic region, wherein the at least one elastic region is formed by providing at least a pair of cutout regions in the single graphite sheet layer or by providing an overlap region where the single graphite sheet layer or the multiple graphite sheet layers overlap.

[0007] The overlap region may be formed by providing at least two foldable portions on a single graphite sheet layer such that an overlap region is provided between the foldable portions, or may be formed by overlapping portions of multiple graphite sheet layers.

[0008] At least one pair of cutout regions may be provided point-symmetrically in a single graphite sheet layer, and the single graphite sheet layer may be connected as a single sheet in areas other than the cutout regions.

[0009] At least one pair of the cutout regions may have a length that is shorter than the graphite sheet layer in a direction perpendicular to the direction of expansion and contraction of the flexible graphite structure.

[0010] The length of the at least one pair of cut-out regions may be 90% or less, or 75% or less, of the length of the graphite sheet layer in a direction perpendicular to the direction of expansion and contraction of the flexible graphite structure.

[0011] At least one stretchable region may include voids that extend in a direction perpendicular to the stretch direction of the flexible graphite structure.

[0012] The gap may be defined between a graphite sheet layer provided in another area other than the overlap area and a graphite sheet layer provided in the overlap area, or may be defined by at least a pair of notch areas.

[0013] When a force is applied to the flexible graphite structure, the graphite sheet units are elongated, the elastic sheet layers are stretched in the direction in which the graphite sheet units are elongated, and the width of the overlapping regions can be narrowed.

[0014] When the force is released, the stretchable sheet layer may contract and the width of the overlap area may increase.

[0015] When a force is applied to the flexible graphite structure, the graphite sheet units are elongated, the elastic sheet layers are stretched in the direction in which the graphite sheet units are elongated, and the size of the gaps in at least one pair of notch regions can increase.

[0016] When the force is released, the elastic sheet layer may contract and reduce the size of the gap in at least one pair of cutout areas.

[0017] The graphite sheet layers may comprise compressed particles of graphitized polymer or expanded graphite, or a combination thereof.

[0018] The elastic sheet layer may contain at least one selected from the group consisting of polydimethylsiloxane (PDMS), epoxy resin, styrene-based material, olefin-based material, polyolefin, polyurethane, thermoplastic polyurethane, thermoplastic elastomer, polyamide, synthetic rubber, polybutadiene, polyisobutylene, polychloroprene, and silicone.

[0019] The elastic sheet layer may have an elongation rate of 175% or more, 200% or more, or 250% or more.

[0020] The stretchable sheet layer may include a thermally conductive material.

[0021] The graphite sheet layer may have a thickness of 15 μm to 19 μm, or 16 μm to 18 μm.

[0022] The graphite sheet unit may include an adhesive layer provided on the graphite sheet layer, and the graphite sheet unit may have a uniform thickness.

[0023] The adhesive layer may include at least one selected from the group consisting of a pressure sensitive adhesive (PSA), a thermosetting adhesive, a photocurable adhesive, an optically clear adhesive (OCA), an optically clear resin (OCR), a double-sided adhesive film, and a single-sided adhesive film.

[0024] When an adhesive layer is formed between a plurality of spaced-apart graphite sheet layers, the adhesive layer may be a double-sided adhesive film.

[0025] When an adhesive layer is formed between the graphite sheet layer and the stretchable sheet layer, the adhesive layer may be a single-sided adhesive film.

[0026] The single-sided adhesive film may be adhered to the surface facing the graphite sheet layer.

[0027] The adhesive layer formed between the graphite sheet layer and the stretchable sheet layer may be divided along the foldable portion of the graphite sheet layer.

[0028] The graphite sheet layer may have an in-plane thermal conductivity of 150 W / mK to 1700 W / mK.

[0029] When the elastic sheet layer is stretched, the length of the elastic sheet layer corresponding to the divided portion of the pressure-sensitive adhesive layer can be extended from more than 0 to less than 50%, or from more than 0 to less than 30%. Effect of the Invention

[0030] According to the disclosed flexible graphite structure, the graphite sheet unit includes at least one stretchable region formed by providing a cutout region or an overlap region, so that the graphite structure can be used as a heat dissipation sheet in a flexible electronic device to ensure excellent heat dissipation.

[0031] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the present disclosure. [Brief description of the drawings]

[0032] [Figure 1A] FIG. 13 is a cross-sectional view of a flexible graphite structure according to one embodiment in which overlap regions are formed as stretchable regions. [Figure 1B] FIG. 1B is a cross-sectional view of the flexible graphite structure of FIG. 1A when the flexible graphite structure is elongated in a stretch direction. [Figure 2A] FIG. 13 is a cross-sectional view of a flexible graphite structure according to one embodiment in which overlap regions are formed as stretchable regions. [Figure 2B] FIG. 2B is a cross-sectional view of the flexible graphite structure of FIG. 2A when the flexible graphite structure is elongated in a stretch direction. [Figure 3A] FIG. 13 is a cross-sectional view of a flexible graphite structure according to one embodiment in which overlap regions are formed as stretchable regions. [Figure 3B] FIG. 3B is a cross-sectional view of the flexible graphite structure of FIG. 3A when the flexible graphite structure is elongated in a stretch direction. [Figure 4A] FIG. 13 is a cross-sectional view of a flexible graphite structure according to one embodiment in which overlap regions are formed as stretchable regions. [Figure 4B] FIG. 4B is a cross-sectional view of the flexible graphite structure of FIG. 4A when the flexible graphite structure is elongated in a stretch direction. [Figure 5A] FIG. 13 is a cross-sectional view of a flexible graphite structure according to one embodiment in which overlap regions are formed as stretchable regions. [Figure 5B] FIG. 5B is a cross-sectional view of the flexible graphite structure of FIG. 5A when the flexible graphite structure is elongated in a stretch direction. [Figure 6A] FIG. 13 is a cross-sectional view of a flexible graphite structure according to one embodiment in which overlap regions are formed as stretchable regions. [Figure 6B] FIG. 6B is a cross-sectional view of the flexible graphite structure of FIG. 6A when the flexible graphite structure is elongated in a stretch direction. [Figure 7A] FIG. 13 is a cross-sectional view of a flexible graphite structure according to one embodiment in which overlap regions are formed as stretchable regions. [Figure 7B] FIG. 7B is a cross-sectional view of the flexible graphite structure of FIG. 7A when the flexible graphite structure is elongated in a stretch direction. [Figure 8A]FIG. 13 is a cross-sectional view of a flexible graphite structure according to one embodiment in which overlap regions are formed as stretchable regions. [Figure 8B] FIG. 8B is a cross-sectional view of the flexible graphite structure of FIG. 8A when the flexible graphite structure is elongated in a stretch direction. [Figure 9A] FIG. 13 is a cross-sectional view of a flexible graphite structure according to one embodiment in which overlap regions are formed as stretchable regions. [Figure 9B] FIG. 9B is a cross-sectional view of the flexible graphite structure of FIG. 9A when the flexible graphite structure is elongated in a stretch direction. [Figure 10A] FIG. 13 is a plan view of a graphite sheet layer according to one embodiment in which cut-out areas are formed as elastic regions. [Figure 10B] FIG. 10B is a cross-sectional view of the graphite sheet layer of FIG. 10A when the graphite sheet layer is elongated in a stretch direction. [Figure 11A] FIG. 13 is a plan view of a graphite sheet layer according to one embodiment in which cut-out areas are formed as elastic regions. [Figure 11B] FIG. 11B is a cross-sectional view of the graphite sheet layer of FIG. 11A when the graphite sheet layer is elongated in a stretch direction. [Figure 12A] 1 is an actual photograph of a flexible graphite structure in accordance with one embodiment in which overlap regions are formed as stretchable regions. [Figure 12B] 12B is an actual photograph of the flexible graphite structure of FIG. 12A when the flexible graphite is stretched in the stretch direction. [Figure 13A] 1 is an actual photograph of a flexible graphite structure with cutout regions formed as stretchable regions according to one embodiment. [Figure 13B] 13B is an actual photograph of the flexible graphite structure of FIG. 13A when the flexible graphite is stretched in the stretch direction. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0033] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings so that those skilled in the art to which the present disclosure pertains can easily carry out the present disclosure. However, the present disclosure may be implemented in many different forms and is not limited to the embodiments described herein. In order to clearly explain the present disclosure using the drawings, parts that are not related to the description are omitted, and similar parts are given similar reference numerals throughout the present specification.

[0034] Throughout this specification, when a part is "connected" to another part, this includes not only "directly connected" but also "electrically connected" with another element interposed therebetween. When a particular part includes a particular component, this means that the particular part may include other elements, rather than excluding other elements, unless otherwise specified.

[0035] FIG. 1A is a cross-sectional view of a flexible graphite structure 100 according to one embodiment of the present disclosure in which overlap regions are formed as stretchable regions.

[0036] Referring to FIG. 1A, a flexible graphite structure 100 includes a graphite sheet layer 110 and elastic sheet layers 120a, 120b attached to either side of the graphite sheet layer 110.

[0037] Graphite sheet layer 110 contains compressed particles of graphitized polymer or exfoliated graphite, and has excellent thermal conductivity in both the vertical and horizontal directions on a two-dimensional plane so that it can be used as a heat dissipation sheet for dissipating heat from a heating element to the outside.

[0038] The graphite sheet layer 110 has a thickness of about 14 μm to 940 μm. The graphite sheet layer 110 may have a thickness of about 14 μm to 20 μm, including about 15 μm to 19 μm and about 16 μm to 18 μm. When the graphite sheet layer 110 is used in a flexible electronic device having a large internal allowable thickness, the graphite sheet layer 110 may have a thickness of about 20 μm to 30 μm, including about 27 μm to 37 μm, about 35 μm to 45 μm, and about 40 μm to 50 μm. The graphite sheet layer 110 may also have a thickness of 40 μm to 940 μm. As the thickness of the graphite sheet layer 110 increases, the heat dissipation performance of the graphite sheet layer may increase. However, the thickness of the graphite sheet layer 110 may be determined according to the size of the space allowable in the flexible electronic device to which the graphite sheet layer 110 is attached.

[0039] The in-plane thermal conductivity of the graphite sheet layer 110 may be between about 150 W / mK and 1700 W / mK.

[0040] Graphite sheet layer 110 includes at least two foldable portions 130 formed by folding graphite sheet layer 110, and an overlap region OL is formed between two foldable portions 130 by the two foldable portions 130. The overlap region OL refers to a region where portions of graphite sheet layer 110 overlap each other when viewed in the vertical direction of FIG. 1A, i.e., in the depth direction of flexible graphite structure 100.

[0041] Elastic sheet layers 120a, 120b are attached to both sides of graphite sheet layer 110, with an overlapping region OL formed by two foldable portions 130 on graphite sheet layer 110. The elastic sheet layer may include any material having an elongation rate described below, and may include, for example, at least one selected from the group consisting of polydimethylsiloxane (PDMS), epoxy resin, styrene-based material, olefin-based material, polyolefin, polyurethane, thermoplastic polyurethane, thermoplastic elastomer, polyamide, synthetic rubber, polybutadiene, polyisobutylene, polychloroprene, and silicone, but is not limited thereto.

[0042] When a force is applied in the longitudinal or transverse direction, the elastic sheet layers 120a, 120b are stretched along the direction in which the force is applied, and when the force is released, the elastic sheet layers 120a, 120b return to their original length. The elastic sheet layers 120a, 120b may have an elongation rate of 175% or more, or 200% or more, or 250% or more, where elongation rate refers to the ratio of the length of the elastic sheet layer when a force is applied to the original length of the elastic sheet when no force is applied. For example, the original length is 100%, so an elongation rate of 175% is 75% greater than the original length (100%). In another example, an elongation rate of 200% is twice (2x) the original length (100%).

[0043] The elastic sheet layers 120a, 120b may include a thermally conductive material. The thermally conductive material may be, but is not limited to, metal beads, polymer beads having high thermal conductivity, etc. Since the elastic sheet layers 120a, 120b include a thermally conductive material, when the flexible graphite structure 100 is used as a heat dissipation sheet for an electronic device, the heat generated in the electronic device can be more efficiently radiated to the outside.

[0044] The foldable portion 130 of the graphite sheet layer 110 and the stretchable sheet layers 120a, 120b are not bonded to each other and may define voids. That is, the overlapping region OL may include voids, and the voids may extend in a direction perpendicular to the stretchability of the flexible graphite structure 100. The presence of the voids allows the flexible graphite structure 100 to elongate in the direction of the force when a force is applied to the flexible graphite structure 100.

[0045] FIG. 1B is a cross-sectional view of flexible graphite structure 100 when flexible graphite structure 100 is stretched in the stretch direction.

[0046] Referring to FIG. 1B , the flexible graphite structure 100 may be used as a heat dissipation sheet in an electronic device equipped with a bendable flexible display or a foldable display that folds and unfolds, and when a user operates the electronic device such that the display of the electronic device is bent or folded, a force pulling the flexible graphite structure 100 to both sides may be applied to the flexible graphite structure 100.

[0047] When a force for pulling the flexible graphite structure 100 is applied to the flexible graphite structure 100, the elastic sheet layers 120a, 120b are stretched along the direction of the force, and since the graphite sheet layer 110 is integrally bonded to the elastic sheet layers 120a, 120b, the graphite sheet layer 110 is also extended on both sides along the direction of the force. Since the graphite sheet layer 110 does not have elasticity, if the graphite sheet layer is a flat graphite sheet, it will not be extended even when a force is applied. However, since the graphite sheet layer 110 of the flexible graphite structure 100 according to the present embodiment has an overlapping region OL formed by the two foldable portions 130, the graphite sheet layer 110 can also be extended on both sides along the direction of the force as the foldable portions 130 of the graphite sheet layer 110 unfold in response to the application of the force.

[0048] As the graphite sheet layer 110 is extended on both sides, the width of the overlapping region OL gradually decreases, and when the graphite sheet layer 110 is maximally extended, the overlapping region OL may disappear.

[0049] Since the graphite sheet layer 110 according to this embodiment has a two-fold shape including two foldable portions 130, the length of the maximally extended flexible graphite structure 100 shown in FIG. 1B can be twice as long as the length of the overlap region OL, which is longer than the length of the flexible graphite structure 100 before extension as shown in FIG. 1A.

[0050] When the user returns the electronic device to its original state after performing the bending or folding operation on the display of the electronic device, the force pulling the flexible graphite structure 100 is released from the flexible graphite structure 100. When the force pulling the flexible graphite structure 100 on both sides is released, the stretchable sheet layers 120a, 120b contract and return to their original length, thus increasing the width of the overlapping region OL, while also forming two foldable portions 130 in the graphite sheet layer 110. When the contraction of the stretchable sheet layers 120a, 120b is completed, the flexible graphite structure 100 returns to its original shape, i.e., the shape shown in FIG. 1A.

[0051] The above-mentioned operation is repeated when a force is applied to and released from the flexible graphite structure 100. This operation allows smooth heat dissipation for flexible electronic devices even when a graphite structure with high thermal conductivity but low flexibility is used as a heat dissipation sheet.

[0052] FIG. 2A is a cross-sectional view of a flexible graphite structure 200 according to one embodiment of the present disclosure in which the overlap regions are formed as stretchable regions.

[0053] Referring to FIG. 2A, a flexible graphite structure 200 includes a graphite sheet unit 215 including two graphite sheet layers 210a, 210b, and elastic sheet layers 220a, 220b attached to both sides of the graphite sheet unit 215.

[0054] Graphite sheet layers 210a, 210b and elastic sheet layers 220a, 220b may be formed from the same materials as the above-mentioned graphite sheet layer 110 and elastic sheet layers 120a, 120b, respectively, and a duplicated description will be omitted.

[0055] The graphite sheet unit 215 includes an overlap region OL formed by overlapping two graphite sheet layers 210a, 210b, where the two graphite sheet layers 210a, 210b overlap each other when viewed in the vertical direction of FIG.

[0056] The elastic sheet layers 220a, 220b are attached to both sides of the graphite sheet unit 215 with an overlapping area OL formed by overlapping the two graphite sheet layers 210a, 210b on the graphite sheet unit 215.

[0057] In the area where the graphite sheet unit 215 has steps, i.e., overlapping area OL, the end portions of the graphite sheet layers 210a, 210b and the stretchable sheet layers 220a, 220b are not bonded to each other, and a void is defined. That is, the overlapping area OL may include a void on both sides thereof, and the void may extend in a direction perpendicular to the stretching direction of the flexible graphite structure 200. Due to the presence of the void, when a force is applied to the flexible graphite structure 200, the flexible graphite structure 200 may be elongated in the direction of the force.

[0058] FIG. 2B is a cross-sectional view of the flexible graphite structure 200 when the flexible graphite structure 200 is stretched in the contraction direction.

[0059] Referring to FIG. 2B, when a user manipulates an electronic device such that the display of the electronic device is bent or folded, a force may be applied to the flexible graphite structure 200 causing the flexible graphite structure 200 to bulge on both sides.

[0060] When a force is applied to the flexible graphite structure 200 to expand the flexible graphite structure 200 on both sides, the elastic sheet layers 220a, 220b are extended along the direction of the force, and since the graphite sheet unit 215 is integrally bonded to the elastic sheet layers 220a, 220b, the graphite sheet layer 210a of the graphite sheet unit 215 moves in one direction, and the graphite sheet layer 210b moves in the opposite direction. In particular, since the two graphite sheet layers 210a, 210b are not bonded to each other but are stacked on each other, the graphite sheet layers can slide in opposite directions due to the application of force. Since the two graphite sheet layers 210a, 210b move in opposite directions, the graphite sheet unit 215 is also extended on both sides.

[0061] As the graphite sheet unit 215 is extended on both sides, the width of the overlapping area OL gradually decreases, allowing the flexible graphite structure 200 to be extended until the overlapping area OL of the two graphite sheet layers 210a, 210b completely disappears.

[0062] When the user returns the electronic device to its original state after performing the operation of bending or folding the display of the electronic device, the force pulling the flexible graphite structure 200 to both sides is released from the flexible graphite structure 200. When the force pulling the flexible graphite structure 200 to both sides is released, the elastic sheet layers 220a, 220b contract and return to their original length again, and therefore the width of the overlapping region OL of the graphite sheet unit 215 increases. When the contraction of the elastic sheet layers 220a, 220b is completed, the flexible graphite structure 200 returns to its original shape, i.e., the shape shown in FIG. 2A.

[0063] The above-mentioned operation is repeated in response to the force applied to and released from the flexible graphite structure 200. This operation allows smooth heat dissipation of a flexible electronic device even when a graphite structure with high thermal conductivity but low flexibility is used as a heat dissipation sheet.

[0064] FIG. 3A is a cross-sectional view of a flexible graphite structure 300 according to one embodiment of the present disclosure in which the overlap regions are formed as stretchable regions.

[0065] Referring to FIG. 3A , flexible graphite structure 300 includes graphite sheet unit 350 including graphite sheet layer 310 and adhesive layers 320a, 320b formed on graphite sheet layer 310, and elastic sheet layers 330a, 330b attached to both outermost surfaces of graphite sheet unit 350.

[0066] Graphite sheet layer 310 and elastic sheet layers 330a, 330b may be formed from the same materials as the graphite sheet layer and elastic sheet layer described above, respectively, and a duplicated description will be omitted.

[0067] Graphite sheet layer 310 includes at least two foldable portions 340 formed by folding graphite sheet layer 310, and an overlap region OL is formed between two foldable portions 340 by the two foldable portions 340. The overlap region OL refers to a region where portions of graphite sheet layer 310 overlap each other when viewed in the vertical direction of FIG. 3A, i.e., in the depth direction of flexible graphite structure 300.

[0068] Adhesive layers 320a, 320b may be formed in portions of graphite sheet layer 310 where overlapping region OL is not formed, and by using adhesive layers 320a, 320b, it is possible to make the thickness of graphite sheet unit 350 approximately uniform.

[0069] The adhesive layers 320a, 320b may include at least one of, but are not limited to, a pressure sensitive adhesive (PSA), a thermosetting adhesive, a photocurable adhesive, an optical clear adhesive (OCA), an optical clear resin (OCR), a double-sided adhesive film, and a single-sided adhesive film. The single-sided adhesive film or the double-sided adhesive film may include, for example, a base layer (not shown) formed of at least one of polyethylene terephthalate (PET), polycarbonate (PC), aluminum foil, copper foil, and polyimide (PI), and an adhesive layer (not shown) in which an adhesive is applied to one or both sides of the base layer.

[0070] The type and shape of adhesive layers 320a, 320b are not particularly limited, but when adhesive layers 320a, 320b are in the form of, for example, a single-sided adhesive film, adhesive layers 320a, 320b can be formed between graphite sheet layer 310 and elastic sheet layers 330a, 330b by being arranged and adhered such that the adhesive layer of the single-sided adhesive film is disposed on the surface facing graphite sheet layer 310.

[0071] Foldable portion 340 of graphite sheet layer 310 and adhesive layers 320a, 320b are not adhered to each other, and voids may be defined. That is, overlapping region OL may include voids on both sides thereof, and the voids may extend in a direction perpendicular to the stretching direction of flexible graphite structure 300. Due to the presence of voids, when a force is applied to flexible graphite structure 300, flexible graphite structure 100 may be elongated along the direction of the force.

[0072] FIG. 3B is a cross-sectional view of the flexible graphite structure 300 when the flexible graphite structure 300 is stretched in the contraction direction.

[0073] Referring to FIG. 3B, when a user manipulates an electronic device such that the display of the electronic device is bent or folded, a force may be applied to the flexible graphite structure 300 that pulls the flexible graphite structure 300 to both sides.

[0074] When a force is applied to the flexible graphite structure 300 to pull it to both sides, the elastic sheet layers 330a, 330b are stretched along the direction of the force, and since the graphite sheet unit 350 is integrally bonded to the elastic sheet layers 330a, 330b and the graphite sheet layer 310 of the flexible graphite structure 300 includes an overlapping region OL formed by the two foldable portions 340, the foldable portions 340 of the graphite sheet layer 310 are unfolded in response to the application of force, and the graphite sheet layer 310 can also be extended to both sides along the direction of the force. In addition, since both sides of adhesive layer 320a are fixedly adhered to graphite sheet layer 310 and elastic sheet layer 330a, and both sides of adhesive layer 320b are fixedly adhered to graphite sheet layer 310 and elastic sheet layer 330b, adhesive layers 320a, 320b move away from each other in response to the extension of elastic sheet layers 330a, 330b and graphite sheet layer 310.

[0075] As the graphite sheet unit 350 is extended on both sides, the width of the overlapping region OL gradually narrows, and when the graphite sheet unit 350 is maximally extended, the overlapping region OL may disappear.

[0076] When a user returns the electronic device to its original state after performing an operation of bending or folding the display of the electronic device, the force pulling the flexible graphite structure 300 to both sides is released from the flexible graphite structure 300. When the force pulling the flexible graphite structure 300 to both sides is released, the elastic sheet layers 330a, 330b contract and return to their original length again, and therefore the width of the overlapping region OL of the graphite sheet portion 350 increases. When the contraction of the elastic sheet layers 330a, 330b is completed, the flexible graphite structure 300 returns to its original shape, i.e., the shape shown in FIG. 3A.

[0077] The above-mentioned operation is repeated according to the force applied to and released from flexible graphite structure 300. This operation allows smooth heat dissipation of a flexible electronic device even when a graphite structure with high thermal conductivity but low flexibility is used as a heat dissipation sheet. In flexible graphite structure 300 according to the present embodiment, the thickness of graphite sheet unit 350 can be made substantially uniform before extension by using adhesive layers 320a, 320b, so that the graphite structure can be more easily attached to a flexible electronic device.

[0078] FIG. 4A is a cross-sectional view of a flexible graphite structure 400 according to one embodiment of the present disclosure in which the overlap regions are formed as stretchable regions.

[0079] Referring to FIG. 4A , flexible graphite structure 400 includes a graphite sheet unit 450 including three graphite sheet layers 410a, 410b, 410c and adhesive layers 420a, 420b, 420c formed on graphite sheet layers 410a, 410b, 410c, and elastic sheet layers 430a, 430b attached to both outermost surfaces of graphite sheet unit 450.

[0080] The three graphite sheet layers 410a, 410b, 410c, the adhesive layers 420a, 420b, 420c, and the elastic sheet layers 430a, 430b may be formed from the same materials as the graphite sheet layers, adhesive layers, and elastic sheet layers described above, respectively, and redundant explanations will be omitted.

[0081] Graphite sheet unit 450 includes an overlap region OL formed by overlapping three graphite sheet layers 410a, 410b, 410c, where the three graphite sheet layers 410a, 410b, 410c overlap each other when viewed vertically in FIG.

[0082] Adhesive layers 420a, 420b, 420c may be formed in the portions where overlapping regions OL of three graphite sheet layers 410a, 410b, 410c are not formed, adhesive layer 420a may be formed between two graphite sheet layers 410b, 410c, and adhesive layers 420b, 420c may be formed between graphite sheet layer 410a and elastic sheet layers 430a, 430b. By using adhesive layers 420a, 420b, 420c, the thickness of graphite sheet unit 450 can be made substantially uniform.

[0083] The type and shape of adhesive layer 420a formed between two graphite sheet layers 410b, 410c spaced apart from each other are not particularly limited. However, when adhesive layer 420a is in the form of an adhesive film, for example, adhesive layers are required on both sides facing graphite sheet layers 410b, 410c in order to adhere to graphite sheet layers 410b, 410c, so the adhesive layer is preferably a double-sided adhesive film.

[0084] When adhesive layers 420b, 420c formed between graphite sheet layer 410a and elastic sheet layers 430a, 430b are in the form of, for example, an adhesive film, each of the adhesive layers may be a single-sided adhesive film or a double-sided adhesive film, since it is sufficient that an adhesive layer is disposed on the surface facing graphite sheet layer 410a.

[0085] In the overlapping region OL, the end portions of the three graphite sheet layers 410a, 410b, 410c and the adhesive layers 420a, 420b, 420c are not adhered to each other, and voids may be defined. That is, the overlapping region OL may include voids on both sides thereof, and the voids may extend in a direction perpendicular to the stretching direction of the flexible graphite structure 400. Due to the presence of the voids, when a force is applied to the flexible graphite structure 400, the flexible graphite structure 100 may be elongated along the direction of the force.

[0086] FIG. 4B is a cross-sectional view of flexible graphite structure 400 when flexible graphite structure 400 is stretched in the contraction direction.

[0087] Referring to FIG. 4B, when a user manipulates an electronic device such that the display of the electronic device is bent or folded, a force may be applied to the flexible graphite structure 400 that pulls the flexible graphite structure 400 to both sides.

[0088] When a force is applied to pull the flexible graphite structure 400 to both sides, the elastic sheet layers 430a and 430b are extended along the direction of the force, and since the graphite sheet unit 450 is integrally bonded to the elastic sheet layers 430a and 430b, the graphite sheet layer 410a of the graphite sheet unit 450 moves in one direction, and the graphite sheet layers 410b and 410c move in the opposite direction. In particular, since the three graphite sheet layers 410a, 410b, and 410c are not bonded to each other but are stacked on top of each other, the graphite sheet layers can slide in opposite directions due to the application of force. Since the graphite sheet layer 410a and the two graphite sheet layers 410b and 410c move in opposite directions, the graphite sheet unit 450 is also extended to both sides.

[0089] As the graphite sheet unit 450 is extended on both sides, the width of the overlapping area OL gradually decreases, allowing the flexible graphite structure 400 to be extended until the overlapping area OL of the three graphite sheet layers 410a, 410b, 410c completely disappears.

[0090] When the user returns the electronic device to its original state after performing the operation of bending or folding the display of the electronic device, the force pulling the flexible graphite structure 400 to both sides is released from the flexible graphite structure 400. When the force pulling the flexible graphite structure 400 to both sides is released, the elastic sheet layers 430a, 430b contract and return to their original length again, and therefore the width of the overlapping region OL of the graphite sheet portion 450 increases. When the contraction of the elastic sheet layers 430a, 430b is completed, the flexible graphite structure 400 returns to its original shape, i.e., the shape shown in FIG. 4A.

[0091] The above-mentioned operation is repeated according to the force applied to and released from flexible graphite structure 400. This operation allows smooth heat dissipation of a flexible electronic device even when a graphite structure with high thermal conductivity but low flexibility is used as a heat dissipation sheet. In flexible graphite structure 400 according to the present embodiment, the thickness of graphite sheet unit 450 can be made substantially uniform before extension by using adhesive layers 420a, 420b, and 420c, so that the graphite structure can be more easily attached to a flexible electronic device.

[0092] FIG. 5A is a cross-sectional view of a flexible graphite structure 500 in which overlap regions are formed as stretchable regions according to one embodiment of the present disclosure.

[0093] Referring to FIG. 5A , a flexible graphite structure 500 includes a graphite sheet unit 550 including two graphite sheet layers 510a, 510b and adhesive layers 520a, 520b formed on the graphite sheet layers 510a, 510b, and elastic sheet layers 530a, 530b attached to both outermost surfaces of the graphite sheet unit 550.

[0094] The two graphite sheet layers 510a, 510b, the adhesive layers 520a, 520b, and the elastic sheet layers 530a, 530b may be formed from the same materials as the graphite sheet layer, adhesive layer, and elastic sheet layer described above, respectively, and redundant explanations will be omitted.

[0095] Graphite sheet unit 550 includes an overlap region OL formed by overlapping two graphite sheet layers 510a, 510b. The overlap region OL refers to the region where the two graphite sheet layers 510a, 510b overlap each other when viewed in the vertical direction of FIG. 5A, i.e., the depth direction of flexible graphite structure 500.

[0096] Adhesive layers 520a, 520b may be formed in areas where overlapping regions OL of graphite sheet layers 510a, 510b are not formed, and by using adhesive layers 520a, 520b, it is possible to make the thickness of graphite sheet unit 550 approximately uniform.

[0097] The type and shape of adhesive layers 520a, 520b are not particularly limited, but when adhesive layers 520a, 520b are in the form of, for example, a single-sided adhesive film, adhesive layers 520a, 520b can be formed between graphite sheet layers 510a, 510b and elastic sheet layers 530a, 530b by being arranged and adhered such that the adhesive layer of the single-sided adhesive film is disposed on the surface facing graphite sheet layers 510a, 510b.

[0098] In the overlapping region OL, the end portions of the two graphite sheet layers 510a, 510b and the adhesive layers 520a, 520b are not adhered to each other, and a void may be defined. That is, the overlapping region OL may include a void on both sides thereof, and the void may extend in a direction perpendicular to the stretching direction of the flexible graphite structure 500. Due to the presence of the void, when a force is applied to the flexible graphite structure 500, the flexible graphite structure 500 may be extended along the direction of the force.

[0099] FIG. 5B is a cross-sectional view of the flexible graphite structure 500 when the flexible graphite structure 500 is stretched in the contraction direction.

[0100] Referring to FIG. 5B, when a user manipulates an electronic device such that the display of the electronic device is bent or folded, a force may be applied to the flexible graphite structure 500 that pulls the flexible graphite structure 500 to both sides.

[0101] When a force pulling the flexible graphite structure 500 to both sides is applied to the flexible graphite structure 500, the elastic sheet layers 530a, 530b are extended along the direction of the force, and since the graphite sheet unit 550 is integrally bonded to the elastic sheet layers 530a, 530b, the graphite sheet layer 510a of the graphite sheet unit 550 moves in one direction, and the graphite sheet layer 510b moves in the opposite direction to the one direction. Also, since both sides of the adhesive layer 520a are fixedly bonded to the graphite sheet layer 510b and the elastic sheet layer 530a, and both sides of the adhesive layer 520b are fixedly bonded to the graphite sheet layer 510a and the elastic sheet layer 530b, the adhesive layers 520a, 520b move away from each other according to the extension of the elastic sheet layers 530a, 530b and the graphite sheet layers 510a, 510b. In particular, the two graphite sheet layers 510a, 510b are not bonded to each other but are stacked on each other, so that the graphite sheet layers can slide in opposite directions upon application of force. As the two graphite sheet layers 510a, 510b move in opposite directions, the graphite sheet unit 550 is also elongated in opposite directions.

[0102] As the graphite sheet unit 550 is extended on both sides, the width of the overlapping area OL gradually decreases, allowing the flexible graphite structure 500 to be extended until the overlapping area OL of the two graphite sheet layers 510a, 510b completely disappears.

[0103] When the user returns the electronic device to its original state after performing the operation of bending or folding the display of the electronic device, the force pulling the flexible graphite structure 500 to both sides is released from the flexible graphite structure 500. When the force pulling the flexible graphite structure 500 to both sides is released, the elastic sheet layers 530a, 530b contract and return to their original length again, and therefore the width of the overlapping region OL of the graphite sheet unit 550 increases. When the contraction of the elastic sheet layers 530a, 530b is completed, the flexible graphite structure 500 returns to its original shape, i.e., the shape shown in FIG. 5A.

[0104] The above-mentioned operation is repeated when a force is applied to flexible graphite structure 500 and released. This operation allows smooth heat dissipation of a flexible electronic device even when a graphite structure with high thermal conductivity but low flexibility is used as a heat dissipation sheet. In flexible graphite structure 500 according to the present embodiment, the thickness of graphite sheet unit 550 can be made substantially uniform before extension by using adhesive layers 520a, 520b, so that the graphite structure can be more easily attached to a flexible electronic device.

[0105] FIG. 6A is a cross-sectional view of a flexible graphite structure 600 in which overlap regions are formed as stretchable regions according to one embodiment of the present disclosure.

[0106] Referring to FIG. 6A , a flexible graphite structure 600 includes a graphite sheet unit 650 including three graphite sheet layers 610a, 610b, 610c and adhesive layers 620a, 620b formed on the graphite sheet layers 610a, 610b, 610c, and elastic sheet layers 630a, 630b attached to both outermost surfaces of the graphite sheet unit 650.

[0107] The graphite sheet layers 610a, 610b, 610c, the adhesive layers 620a, 620b, and the elastic sheet layers 630a, 630b may be formed from the same materials as the graphite sheet layers, adhesive layers, and elastic sheet layers described above, respectively, and redundant explanations will be omitted.

[0108] Graphite sheet layer 610a includes at least two foldable portions 640 formed by folding graphite sheet layer 610a, and an overlap region OL is formed between the two foldable portions 640 by the two foldable portions 640. The overlap region OL refers to a region where portions of graphite sheet layer 610a overlap each other when viewed in the vertical direction of FIG. 6A, i.e., in the depth direction of flexible graphite structure 600.

[0109] Adhesive layers 620a and 620b may be formed in the portions where overlapping regions OL of graphite sheet layers 610a, 610b, and 610c are not formed, adhesive layer 620a may be formed between graphite sheet layer 610a and graphite sheet layer 610b, and adhesive layer 620b may be formed between graphite sheet layer 610a and graphite sheet layer 610c. By using adhesive layers 620a and 620b and graphite sheet layers 610b and 610c, the thickness of graphite sheet unit 650 can be made substantially uniform.

[0110] The type and shape of the adhesive layers 620a, 620b formed between the graphite sheet layers 610a, 610b, 610c spaced apart from each other are not particularly limited. However, when the adhesive layers 620a, 620b are in the form of an adhesive film, for example, the adhesive layers are required on both sides facing the graphite sheet layers 610a, 610b, 610c in order to adhere to the graphite sheet layers 610a, 610b, 610c, so the adhesive layers are preferably double-sided adhesive films.

[0111] Foldable portion 640 of graphite sheet layer 610a, adhesive layers 620a, 620b, and graphite sheet layers 610b, 610c are not bonded to each other, and voids may be defined. That is, overlapping region OL may include voids on both sides thereof, and the voids may extend in a direction perpendicular to the direction of expansion and contraction of flexible graphite structure 600. Due to the presence of voids, when a force is applied to flexible graphite structure 600, flexible graphite structure 600 may be elongated along the direction of the force.

[0112] FIG. 6B is a cross-sectional view of flexible graphite structure 600 when flexible graphite structure 600 is stretched in the contraction direction.

[0113] Referring to FIG. 6B, when a user manipulates an electronic device such that the display of the electronic device is bent or folded, a force may be applied to the flexible graphite structure 600 that pulls the flexible graphite structure 600 to both sides.

[0114] When a force is applied to the flexible graphite structure 600 to pull the flexible graphite structure 600 to both sides, the elastic sheet layers 630a, 630b are stretched along the direction of the force, and since the graphite sheet unit 650 is integrally bonded to the elastic sheet layers 630a, 630b and the graphite sheet layer 610a of the flexible graphite structure 600 includes an overlapping region OL formed by the two foldable portions 640, the foldable portion 640 of the graphite sheet layer 610a is unfolded in response to the application of force, and the graphite sheet layer 610a can also be extended to both sides along the direction of the force. In addition, since both sides of the adhesive layers 620a, 620b are fixedly attached between the graphite sheet layers 610a, 610b, 610c and both sides of the graphite sheet layers 610b, 610c are fixedly attached between the elastic sheet layers 630a, 630b and the adhesive layers 620a, 620b, the adhesive layers 620a, 620b and the graphite sheet layers 610b, 610c also move away from each other in response to the extension of the elastic sheet layers 630a, 630b and the graphite sheet layer 610a.

[0115] As the graphite sheet unit 650 is extended on both sides, the width of the overlapping region OL gradually narrows, and when the graphite sheet unit 650 is maximally extended, the overlapping region OL may disappear.

[0116] When the user returns the electronic device to its original state after performing the operation of bending or folding the display of the electronic device, the force pulling the flexible graphite structure 600 to both sides is released from the flexible graphite structure 600. When the force pulling the flexible graphite structure 600 to both sides is released, the elastic sheet layers 630a, 630b contract and return to their original length again, and therefore the width of the overlapping region OL of the graphite sheet unit 650 increases. When the contraction of the elastic sheet layers 630a, 630b is completed, the flexible graphite structure 600 returns to its original shape, i.e., the shape shown in FIG. 6A.

[0117] The above-mentioned operation is repeated when a force is applied to and released from flexible graphite structure 600. This operation allows smooth heat dissipation of a flexible electronic device even when a graphite structure with high thermal conductivity but low flexibility is used as a heat dissipation sheet. In flexible graphite structure 600 according to the present embodiment, the thickness of graphite sheet unit 650 can be made substantially uniform before extension by using adhesive layers 620a, 620b and graphite sheet layers 610b, 610c, so that the graphite structure can be more easily attached to a flexible electronic device.

[0118] FIG. 7A is a cross-sectional view of a flexible graphite structure 700 according to one embodiment of the present disclosure in which the overlap regions are formed as stretchable regions.

[0119] Referring to FIG. 7A , a flexible graphite structure 700 includes a graphite sheet unit 750 including four graphite sheet layers 710a, 710b, 710c, 710d and adhesive layers 720a, 720b formed on the graphite sheet layers 710a, 710b, 710c, 710d, and elastic sheet layers 730a, 730b attached to both outermost surfaces of the graphite sheet unit 750.

[0120] The graphite sheet layers 710a, 710b, 710c, 710d, the adhesive layers 720a, 720b, and the elastic sheet layers 730a, 730b may be formed from the same materials as the graphite sheet layers, adhesive layers, and elastic sheet layers described above, respectively, and redundant explanations will be omitted.

[0121] Graphite sheet unit 750 includes an overlap region OL formed by overlapping two graphite sheet layers 710a, 710b, where the two graphite sheet layers 710a, 710b overlap each other when viewed vertically in FIG.

[0122] Adhesive layers 720a and 720b may be formed in the portions where overlapping regions OL of graphite sheet layers 710a, 710b, 710c, and 710d are not formed, adhesive layer 720a may be formed between graphite sheet layer 710b and graphite sheet layer 710c, and adhesive layer 720b may be formed between graphite sheet layer 710a and graphite sheet layer 710d. By using adhesive layers 720a and 720b and graphite sheet layers 710c and 710d, the thickness of graphite sheet unit 750 can be made substantially uniform.

[0123] The type and shape of adhesive layers 720a, 720b formed between graphite sheet layers 710a, 710b, 710c, 710d spaced apart from one another are not particularly limited. However, when adhesive layers 720a, 720b are in the form of, for example, an adhesive film, adhesive layers are required on both sides facing graphite sheet layers 710a, 710b, 710c, 710d to adhere to graphite sheet layers 710a, 710b, 710c, 710d, so the adhesive layer is preferably a double-sided adhesive film.

[0124] In the overlap region OL, the end portions of the two graphite sheet layers 710a, 710b are not adhered to the adhesive layers 720a, 720b and the graphite sheet layers 710c, 710d, and a void may be defined. That is, the overlap region OL may include a void on both sides thereof, and the void may extend in a direction perpendicular to the stretching direction of the flexible graphite structure 700. Due to the presence of the void, when a force is applied to the flexible graphite structure 700, the flexible graphite structure 100 may be elongated along the direction of the force.

[0125] FIG. 7B is a cross-sectional view of flexible graphite structure 700 when flexible graphite structure 700 is stretched in the contraction direction.

[0126] Referring to FIG. 7B, when a user manipulates an electronic device such that the display of the electronic device is bent or folded, a force may be applied to the flexible graphite structure 700 that pulls the flexible graphite structure 700 to either side.

[0127] When a force is applied to flexible graphite structure 700 to pull it to both sides, elastic sheet layers 730a, 730b are elongated along the direction of the force, and since graphite sheet unit 750 is integrally bonded to elastic sheet layers 730a, 730b, graphite sheet layer 710a of graphite sheet unit 750 moves in one direction and graphite sheet layer 710b moves in the opposite direction. In addition, since both sides of the adhesive layers 720a, 720b are fixedly attached between the graphite sheet layers 710a, 710b, 710c, 710d, and both sides of the graphite sheet layers 710c, 710d are fixedly attached between the elastic sheet layers 730a, 730b and the adhesive layers 720a, 720b, the adhesive layers 720a, 720b and the graphite sheet layers 710c, 710d also move away from each other according to the extension of the elastic sheet layers 730a, 730b and the graphite sheet layers 710a, 710b. In particular, since the two graphite sheet layers 710a, 710b are not bonded to each other but are stacked on each other, the graphite sheet layers can slide in opposite directions by the application of force. As the two graphite sheet layers 710a, 710b move in opposite directions, the graphite sheet unit 750 is also extended on both sides.

[0128] As the graphite sheet unit 750 is extended on both sides, the width of the overlapping area OL gradually decreases, allowing the flexible graphite structure 700 to be extended until the overlapping area OL of the two graphite sheet layers 710a, 710b completely disappears.

[0129] When the user returns the electronic device to its original state after performing the operation of bending or folding the display of the electronic device, the force pulling the flexible graphite structure 700 to both sides is released from the flexible graphite structure 700. When the force pulling the flexible graphite structure 700 to both sides is released, the elastic sheet layers 730a, 730b contract and return to their original length again, and thus the width of the overlapping region OL of the graphite sheet unit 750 increases. When the contraction of the elastic sheet layers 730a, 730b is completed, the flexible graphite structure 700 returns to its original shape, i.e., the shape shown in FIG. 7A.

[0130] The above-mentioned operation is repeated when a force is applied to and released from flexible graphite structure 700. This operation allows smooth heat dissipation of a flexible electronic device even when a graphite structure with high thermal conductivity but low flexibility is used as a heat dissipation sheet. In flexible graphite structure 700 according to the present embodiment, the thickness of graphite sheet unit 750 can be made substantially uniform before extension by using adhesive layers 720a, 720b and graphite sheet layers 710c, 710d, so that the graphite structure can be more easily attached to a flexible electronic device.

[0131] FIG. 8A is a cross-sectional view of a flexible graphite structure 800 according to one embodiment of the present disclosure in which the overlap regions are formed as stretchable regions.

[0132] Referring to FIG. 8A , a flexible graphite structure 800 includes a graphite sheet unit 870 including three graphite sheet layers 810a, 810b, 810c and adhesive layers 820a, 820b, 830a, 830b, 840a, 840b formed on the graphite sheet layers 810a, 810b, 810c, and elastic sheet layers 850a, 850b attached to both outermost surfaces of the graphite sheet unit 870.

[0133] Graphite sheet layers 810a, 810b, 810c, adhesive layers 820a, 820b, 830a, 830b, 840a, 840b, and elastic sheet layers 850a, 850b may be formed from the same materials as the graphite sheet layers, adhesive layers, and elastic sheet layers described above, respectively, and redundant explanations will be omitted.

[0134] Graphite sheet layer 810a includes at least two foldable portions 860 formed by folding graphite sheet layer 810a, and an overlap region OL is formed between the two foldable portions 860 by the two foldable portions 860. The overlap region OL refers to a region where portions of graphite sheet layer 810a overlap each other when viewed in the vertical direction of FIG. 8A, i.e., in the depth direction of flexible graphite structure 800.

[0135] Adhesive layers 820a and 820b may be formed in the portions where overlapping regions OL of graphite sheet layers 810a, 810b, and 810c are not formed, adhesive layer 820a may be formed between graphite sheet layer 810a and graphite sheet layer 810b, and adhesive layer 820b may be formed between graphite sheet layer 810a and graphite sheet layer 810c. Adhesive layers 830a and 830b may be formed between graphite sheet layers 810a and 810b and elastic sheet layer 850a, and adhesive layers 840a and 840b may be formed between graphite sheet layers 810a and 810c and elastic sheet layer 850b. Also, adhesive layers 830a, 830b, 840a, 840b formed between graphite sheet layers 810a, 810b, 810c and elastic sheet layers 850a, 850b may be divided along foldable portion 860 of graphite sheet layer 810a. By using adhesive layers 820a, 820b, 830a, 830b, 840a, 840b and graphite sheet layers 810b, 810c, it is possible to make the thickness of graphite sheet unit 850 approximately uniform.

[0136] The type and shape of adhesive layers 820a, 820b formed between graphite sheet layers 810a, 810b, 810c spaced apart from each other are not particularly limited. However, when adhesive layers 820a, 820b are in the form of an adhesive film, for example, adhesive layers are required on both sides facing graphite sheet layers 810a, 810b, 810c to adhere to graphite sheet layers 810a, 810b, 810c, so the adhesive layer is preferably a double-sided adhesive film.

[0137] When the adhesive layers 830a, 830b, 840a, 840b formed between the graphite sheet layers 810a, 810b, 810c and the elastic sheet layers 850a, 850b are in the form of, for example, adhesive films, each of the adhesive layers may be a single-sided adhesive film as well as a double-sided adhesive film, since it is sufficient that an adhesive layer is disposed on the surface facing the graphite sheet layer 810a, 810b, or 810c.

[0138] Graphite sheet layer 810a, adhesive layers 820a, 820b, and foldable portions 860 of graphite sheet layers 810b, 810c are not bonded to each other, and adhesive layers 830a, 830b, 840a, 840b are interrupted along foldable portions 860, and voids may be defined therebetween. Thus, overlapping region OL may include voids on both sides thereof, and the voids may extend in a direction perpendicular to the stretching direction of flexible graphite structure 800. Due to the presence of the voids, when a force is applied to flexible graphite structure 800, flexible graphite structure 800 may be elongated along the direction of the force.

[0139] FIG. 8B is a cross-sectional view of flexible graphite structure 800 when flexible graphite structure 800 is stretched in the contraction direction.

[0140] Referring to FIG. 8B, when a user manipulates an electronic device such that the display of the electronic device is bent or folded, a force may be applied to the flexible graphite structure 800 that pulls the flexible graphite structure 800 to both sides.

[0141] When a force is applied to the flexible graphite structure 800 to pull the flexible graphite structure 800 to both sides, the elastic sheet layers 850a, 850b are stretched along the direction of the force, and since the graphite sheet unit 870 is integrally bonded to the elastic sheet layers 850a, 850b and the graphite sheet layer 810a of the flexible graphite structure 800 includes an overlapping region OL formed by two foldable portions 860, the foldable portion 860 of the graphite sheet layer 810a is unfolded in response to the application of force, and the graphite sheet layer 810a can also be extended to both sides along the direction of the force. Furthermore, since adhesive layers 820a, 820b, 830a, 830b, 840a, 840b and graphite sheet layers 810b, 810c are fixedly stacked between graphite sheet layer 810a and elastic sheet layers 850a, 850b, adhesive layers 820a, 830a, 840b and graphite sheet layer 810b move away from adhesive layers 820b, 830b, 840a and graphite sheet layer 810c in response to the extension of elastic sheet layers 850a, 850b and graphite sheet layer 810a.

[0142] When the elastic sheet layers 850a, 850b are stretched, the elastic sheet layers 850a, 850b corresponding to the separation between the adhesive layers 830a, 830b and the separation between the adhesive layers 840a, 840b can be stretched from greater than 0 to less than 50%, or from greater than 0 to less than 30%.

[0143] As the graphite sheet unit 870 is extended on both sides, the width of the overlapping region OL gradually narrows, and when the graphite sheet unit 870 is maximally extended, the overlapping region OL may disappear.

[0144] When the user returns the electronic device to its original state after performing the operation of bending or folding the display of the electronic device, the force pulling the flexible graphite structure 800 to both sides is released from the flexible graphite structure 800. When the force pulling the flexible graphite structure 800 to both sides is released, the elastic sheet layers 850a, 850b contract and return to their original length again, and thus the width of the overlapping region OL of the graphite sheet unit 870 increases. When the contraction of the elastic sheet layers 850a, 850b is completed, the flexible graphite structure 800 returns to its original shape, i.e., the shape shown in FIG. 8A.

[0145] FIG. 9A is a cross-sectional view of a flexible graphite structure 900 according to one embodiment of the present disclosure in which the overlapping regions are formed as stretchable regions.

[0146] Referring to FIG. 9A , a flexible graphite structure 900 includes a graphite sheet unit 960 including four graphite sheet layers 910a, 910b, 910c, 910d, adhesive layers 920a, 920b, 930a, 930b, 940a, 940b formed on the graphite sheet layers 910a, 910b, 910c, 910d, and elastic sheet layers 950a, 950b attached to both outermost surfaces of the graphite sheet unit 960.

[0147] Graphite sheet layers 910a, 910b, 910c, 910d, adhesive layers 920a, 920b, 930a, 930b, 940a, 940b, and elastic sheet layers 950a, 950b may be formed from the same materials as the graphite sheet layers, adhesive layers, and elastic sheet layers described above, respectively, and redundant explanations will be omitted.

[0148] The graphite sheet unit 960 includes an overlap region OL formed by overlapping two graphite sheet layers 910a, 910b, where the two graphite sheet layers 910a, 910b overlap each other when viewed vertically in FIG.

[0149] Adhesive layers 920a and 920b may be formed in the portions where overlapping regions OL of graphite sheet layers 910a, 910b, 910c, and 910d are not formed, adhesive layer 920a may be formed between graphite sheet layer 910b and graphite sheet layer 910c, and adhesive layer 920b may be formed between graphite sheet layer 910a and graphite sheet layer 910d. Adhesive layers 930a and 930b may be formed between graphite sheet layers 910a and 910c and elastic sheet layer 950a, and adhesive layers 940a and 940b may be formed between graphite sheet layers 910b and 910d and elastic sheet layer 950b. In addition, adhesive layers 930a, 930b, 940a, 940b formed between graphite sheet layers 910a, 910b, 910c, 910d and elastic sheet layers 950a, 950b may be divided along the edge portions of graphite sheet layers 910a, 910b in overlapping regions OL. By using adhesive layers 920a, 920b, 930a, 930b, 940a, 940b and graphite sheet layers 910c, 910d, the thickness of graphite sheet unit 960 can be made substantially uniform.

[0150] The type and shape of adhesive layers 920a, 920b formed between graphite sheet layers 910a, 910b, 910c, 910d spaced apart from one another are not particularly limited. However, when adhesive layers 920a, 920b are in the form of, for example, an adhesive film, adhesive layers are required on both sides facing graphite sheet layers 910a, 910b, 910c, 910d in order to adhere to graphite sheet layers 910a, 910b, 910c, 910d, so the adhesive layer is preferably a double-sided adhesive film.

[0151] When adhesive layers 930a, 930b, 940a, 940b formed between graphite sheet layers 910a, 910b, 910c, 910d and elastic sheet layers 950a, 950b are in the form of, for example, adhesive films, each of the adhesive layers may be a single-sided adhesive film as well as a double-sided adhesive film, since it is sufficient that an adhesive layer be disposed on the surface facing graphite sheet layer 910a, 910b, 910c, or 910d.

[0152] In the overlapping region OL, the end portions of the two graphite sheet layers 910a, 910b are not adhered to the adhesive layers 920a, 920b and the graphite sheet layers 910c, 910d, and the adhesive layers 930a, 930b, 940a, 940b are separated along the end portions of the graphite sheet layers 910a, 910b, so that a gap may be defined between them. Thus, the overlapping region OL may include a gap on both sides thereof, and the gap may extend in a direction perpendicular to the stretching direction of the flexible graphite structure 900. Due to the presence of the gap, when a force is applied to the flexible graphite structure 900, the flexible graphite structure 900 may be extended along the direction of the force.

[0153] FIG. 9B is a cross-sectional view of the flexible graphite structure 900 when the flexible graphite structure 900 is stretched in the contraction direction.

[0154] Referring to FIG. 9B, when a user manipulates an electronic device such that the display of the electronic device is bent or folded, a force may be applied to the flexible graphite structure 900 that pulls the flexible graphite structure 900 to both sides.

[0155] When a force is applied to the flexible graphite structure 900 to pull it to both sides, the elastic sheet layers 950a, 950b are elongated along the direction of the force, and since the graphite sheet unit 960 is integrally bonded to the elastic sheet layers 950a, 950b, the graphite sheet layer 910a of the graphite sheet unit 960 moves in one direction and the graphite sheet layer 910b moves in the opposite direction. Also, since the adhesive layers 920a, 920b, 930a, 930b, 940a, 940b and the graphite sheet layers 910c, 910d are stacked between the graphite sheet layers 910a, 910b and the stretchable sheet layers 950a, 950b, the adhesive layers 920a, 930a, 940b and the graphite sheet layer 910c move away from the adhesive layers 920b, 930b, 940a and the graphite sheet layer 910d in response to the extension of the stretchable sheet layers 950a, 950b and the graphite sheet layers 910a, 910b. In particular, since the two graphite sheet layers 910a, 910b are not adhered to each other but are stacked on each other, the graphite sheet layers can slide in opposite directions by the application of force. As the two graphite sheet layers 910a, 910b move in opposite directions, the graphite sheet unit 960 is also extended on both sides.

[0156] As the graphite sheet unit 960 is extended on both sides, the width of the overlapping area OL gradually decreases, allowing the flexible graphite structure 900 to be extended until the overlapping area OL of the two graphite sheet layers 910a, 910b completely disappears.

[0157] When the user returns the electronic device to its original state after performing the operation of bending or folding the display of the electronic device, the force pulling the flexible graphite structure 900 to both sides is released from the flexible graphite structure 900. When the force pulling the flexible graphite structure 900 to both sides is released, the elastic sheet layers 950a, 950b contract and return to their original length again, and therefore the width of the overlapping region OL of the graphite sheet unit 960 increases. When the contraction of the elastic sheet layers 950a, 950b is completed, the flexible graphite structure 900 returns to its original shape, i.e., the shape shown in FIG. 9A.

[0158] FIG. 10A is a plan view of a graphite sheet layer 10 applicable to a flexible graphite structure according to one embodiment of the present disclosure, in which cut-out regions are formed as elastic regions.

[0159] 10A, graphite sheet layer 10 includes two cutout regions 12a, 12b, which are symmetrically provided in graphite sheet layer 10. Graphite sheet layer 10 may be formed of the same material as the graphite sheet layer described above, and a duplicated description will be omitted.

[0160] The length of the two cutout regions 12a, 12b in a direction perpendicular to the stretching direction E of graphite sheet layer 10 may be shorter than the length of graphite sheet layer 10 in the vertical direction, with cutout region 12a cutting one end portion of graphite sheet layer 10 and cutout region 12b cutting the other end portion of graphite sheet layer 10. In addition, the length of the two cutout regions 12a, 12b in the direction perpendicular to the stretching direction E is 90% or less, or 75% or less, of the length of graphite sheet layer 10 in the vertical direction.

[0161] Since the length of cutout regions 12a, 12b in a direction perpendicular to the stretching direction E is shorter than the length of graphite sheet layer 10 in the perpendicular direction, graphite sheet layer 10 is connected as a single sheet in areas other than cutout regions 12a, 12b.

[0162] In the graphite sheet layer 10, voids are defined by the cut-out regions 12a, 12b, and the voids extend in a direction perpendicular to the stretch direction E.

[0163] FIG. 10B is a plan view of graphite sheet layer 10 in the form of a flexible graphite structure in which elastic sheet layers (not shown) formed on both sides of graphite sheet layer 10 extend in elastic direction E.

[0164] 10B, the flexible graphite structure including the graphite sheet layer 10 may be used as a heat dissipation sheet in an electronic device equipped with a bendable flexible display or a foldable display that folds and unfolds. When a user operates the electronic device such that the display of the electronic device is bent or folded, a force that pulls the graphite sheet layer 10 of the flexible graphite structure to both sides may be applied to the graphite sheet layer 10.

[0165] When a tensile force is applied to graphite sheet layer 10 in the stretching direction E, the elastic sheet layers formed on both sides of graphite sheet layer 10 are stretched along the direction of the force. Since graphite sheet layer 10 is integrally bonded to the elastic sheet layer, graphite sheet layer 10 also extends in the stretching direction E along the direction of the force.

[0166] Since graphite sheet layer 10 does not have elasticity, if the graphite sheet layer were a flat graphite sheet, it would be torn apart without being stretched even when a force is applied to it. However, since graphite sheet layer 10 includes cutout regions 12a, 12b, graphite sheet layer 10 can also be stretched in the elastic direction E along the direction of the force in response to the application of force.

[0167] When a user returns the electronic device to its original state after performing an operation of bending or folding the display of the electronic device, the tensile force in the stretching direction E is released from the graphite sheet layer 10 of the flexible graphite structure. When the force pulling the graphite sheet layer 10 in the stretching direction E is released, the stretchable sheet layer contracts and returns to its original length, and therefore the notched regions 12a, 12b of the graphite sheet layer 10 also shrink. When the contraction of the stretchable sheet layer is completed, the graphite sheet layer 10 returns to its original shape, i.e., the shape shown in FIG. 10A.

[0168] Fig. 11A is a plan view of a graphite sheet layer 20 applicable to a flexible graphite structure according to an embodiment of the present disclosure in which the cutout regions are formed as elastic regions. Fig. 11B is a plan view of graphite sheet layer 20 in a flexible graphite structure in which elastic sheet layers (not shown) formed on both sides of graphite sheet layer 20 extend in the elastic direction E.

[0169] 11A and 11B, graphite sheet layer 20 includes two cutout regions 22a, 22b, and one end of each of cutout regions 22a, 22b may be curved in the stretching direction E. The characteristics of graphite sheet layer 20 and two cutout regions 22a, 22b are the same as the characteristics of graphite sheet layer 10 and two cutout regions 12a, 12b described above, and therefore will not be described again.

[0170] FIG. 12A is an actual photograph of a flexible graphite structure according to one embodiment with overlap regions provided as stretchable regions, with the overlap regions formed, i.e., before a force is applied to the flexible graphite structure pulling it to either side.

[0171] Fig. 12B is an actual photograph of the flexible graphite structure of Fig. 12A when it is stretched in the stretching direction. When a force is applied to the flexible graphite structure to pull it to both sides, the width of the overlapping region gradually narrows, while the stretchable sheet layer and the graphite sheet layer of the flexible graphite structure are stretched to both sides along the direction of the force. When the graphite sheet layer is stretched to the maximum, the overlapping region disappears, and the shape shown in Fig. 12B may be shown.

[0172] When the force pulling the flexible graphite structure of FIG. 12B against each other is released, the stretchable sheet layer contracts back to its original length, thus reforming the overlap area so that the flexible graphite structure can return to the shape of FIG. 12A.

[0173] 13A is an actual photograph of a flexible graphite structure according to an embodiment in which cutout regions are formed as stretchable regions. The flexible graphite structure has two cutout regions formed in a direction perpendicular to the stretchable direction. The length of the two cutout regions is shorter than the length of the graphite sheet layer in a direction parallel to the cutout regions, so the graphite sheet layer is connected as a single sheet except for the two cutout regions.

[0174] Fig. 13B is an actual photograph of the flexible graphite structure of Fig. 13A being stretched in the stretching direction. When a force is applied to both sides of the flexible graphite structure of Fig. 13A, the notched area of ​​the graphite sheet layer can be expanded, and the graphite sheet layer can also be stretched along the direction of the force.

[0175] When the force pulling the flexible graphite structure of Fig. 13B on both sides is released, the stretchable sheet layer contracts back to its original length, thus reducing the notched area of ​​the graphite sheet layer. Once the contraction of the stretchable sheet layer is complete, the flexible graphite structure may return to its original shape, i.e., the shape shown in Fig. 13A.

[0176] The above-mentioned operation is repeated when a force is applied to the graphite sheet layers 10, 20 of the flexible graphite structure and then released. This operation allows smooth heat dissipation of a flexible electronic device even when a graphite structure with high thermal conductivity but low flexibility is used as a heat dissipation sheet.

[0177] The flexible graphite structure has been described above with reference to the embodiments shown in the drawings, which are merely exemplary. Those skilled in the art will appreciate that various modifications and other equivalent embodiments are possible from these embodiments. Although the embodiments shown in the drawings include up to four graphite sheet layers in the graphite structure, it should be understood that the graphite structure of the present disclosure includes a single graphite sheet layer or multiple graphite sheet layers, including but not limited to at least two graphite sheet layers, at least three graphite sheet layers, at least four graphite sheet layers, at least five graphite sheet layers, etc. Thus, the embodiments disclosed herein should be considered in a descriptive rather than a restrictive sense. The scope of the present disclosure is expressed in the appended claims, not in the above description, and all differences that are within the scope of the claims should be understood to be within the scope of the present disclosure.

[0178] Although specific embodiments have been described, these embodiments are presented by way of example only and are not intended to limit the scope of the present disclosure. In fact, the embodiments described herein may be embodied in various other forms. In addition, various omissions, substitutions, and modifications of the forms of the embodiments described herein may be made without departing from the spirit of the present disclosure. The appended claims and their equivalents are intended to cover such forms and modifications as fall within the scope and spirit of the present disclosure.

Claims

1. a graphite sheet unit including a single graphite sheet layer or multiple graphite sheet layers having at least one elastic region; an elastic sheet layer attached to at least one of both outermost surfaces of the graphite sheet unit and configured to cover the at least one elastic region; Including, The at least one elastic region is formed by providing at least a pair of cutout regions in the single graphite sheet layer, or by providing an overlap region in which the single graphite sheet layer or the multiple graphite sheet layers overlap. Flexible graphite structure.

2. 2. The flexible graphite structure of claim 1, wherein the overlap region is formed by providing at least two foldable portions in the single graphite sheet layer such that the overlap region is provided between the foldable portions, or by overlapping portions of the multiple graphite sheet layers.

3. the at least one pair of cutout regions are provided point-symmetrically in the single graphite sheet layer; 2. The flexible graphite structure of claim 1, wherein the single graphite sheet layer is connected in one sheet in areas other than the cutout areas.

4. 4. The flexible graphite structure of claim 3, wherein the at least one pair of cut-out regions has a length that is shorter than the graphite sheet layer in a direction perpendicular to a direction of expansion and contraction of the flexible graphite structure.

5. 5. The flexible graphite structure of claim 4, wherein the length of the at least one pair of cut out regions is 90% or less or 75% or less of a length of the graphite sheet layer in the direction perpendicular to the stretch direction of the flexible graphite structure.

6. 10. The flexible graphite structure of claim 1, wherein the at least one stretchable region comprises voids extending in a direction perpendicular to the stretch direction of the flexible graphite structure.

7. 7. The flexible graphite structure of claim 6, wherein the void is defined between a graphite sheet layer provided in another area other than the overlapping area and a graphite sheet layer provided in the overlapping area, or is defined by the at least one pair of cutout areas.

8. 3. The flexible graphite structure of claim 2, wherein when a force is applied to the flexible graphite structure, the graphite sheet units are elongated, the elastic sheet layers are stretched in a direction in which the graphite sheet units are elongated, and the width of the overlapping regions is narrowed.

9. 9. The flexible graphite structure of claim 8, wherein when the force is released, the elastic sheet layer contracts and the width of the overlap region increases.

10. 4. The flexible graphite structure of claim 3, wherein when a force is applied to the flexible graphite structure, the graphite sheet unit is elongated, the elastic sheet layer is stretched in a direction in which the graphite sheet unit is elongated, and a size of a gap in the at least one pair of notch regions is enlarged.

11. 11. The flexible graphite structure of claim 10, wherein when the force is released, the elastic sheet layer contracts and the size of the voids in the at least one pair of cutout areas decreases.

12. 10. The flexible graphite structure of claim 1, wherein the graphite sheet layers comprise compressed particles of graphitized polymer or expanded graphite, or a combination thereof.

13. 10. The flexible graphite structure of claim 1, wherein the elastic sheet layer comprises at least one selected from the group consisting of PDMS (polydimethylsiloxane), epoxy resin, styrene-based material, olefin-based material, polyolefin, polyurethane, thermoplastic polyurethane, thermoplastic elastomer, polyamide, synthetic rubber, polybutadiene, polyisobutylene, polychloroprene, and silicone.

14. 10. The flexible graphite structure of claim 1, wherein the stretchable sheet layer has an elongation of 175% or more, or 200% or more, or 250% or more.

15. The flexible graphite structure of claim 1 , wherein the stretchable sheet layer comprises a thermally conductive material.

16. 2. The flexible graphite structure of claim 1, wherein the graphite sheet layer has a thickness of 15 μm to 19 μm, or 16 μm to 18 μm.

17. 3. The flexible graphite structure of claim 2, wherein the graphite sheet unit includes an adhesive layer disposed on the graphite sheet layer, and the graphite sheet unit has a uniform thickness.

18. 20. The flexible graphite structure of claim 17, wherein the adhesive layer comprises at least one selected from the group consisting of a pressure sensitive adhesive (PSA), a thermoset adhesive, a photocurable adhesive, an optically clear adhesive (OCA), an optically clear resin (OCR), a double-sided adhesive film, and a single-sided adhesive film.

19. 20. The flexible graphite structure of claim 18, wherein when the adhesive layer is formed between the plurality of spaced-apart graphite sheet layers, the adhesive layer is a double-sided adhesive film.

20. 20. The flexible graphite structure of claim 18, wherein when the adhesive layer is formed between the graphite sheet layer and the elastic sheet layer, the adhesive layer is a single-sided adhesive film.

21. 21. The flexible graphite structure of claim 20, wherein the single-sided adhesive film is adhered to a surface facing the graphite sheet layer.

22. 21. The flexible graphite structure of claim 20, wherein the adhesive layer formed between the graphite sheet layer and the stretchable sheet layer is interrupted along the foldable portion of the graphite sheet layer.

23. 13. The flexible graphite structure of claim 12, wherein the graphite sheet layers have an in-plane thermal conductivity of between 150 W / mK and 1700 W / mK.

24. 23. The flexible graphite structure of claim 22, wherein when the elastic sheet layer is stretched, a length of the elastic sheet layer corresponding to the interrupted portion of the pressure-sensitive adhesive layer is extended from greater than 0 to less than 50%, or from greater than 0 to less than 30%.

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