KR20150106273A - Double heat dissipation sheet, manufacturing method thereof and portable terminal having the same - Google Patents

Abstract

The present invention relates to a double heat radiation sheet, a manufacturing method thereof, and a portable terminal including the same. The double heat radiation sheet includes: a first heat radiation unit which has a first thermal conductivity, and diffuses the transmitted heat; and a second heat radiation unit which is bonded to the first heat radiation unit, has a second thermal conductivity different from the first thermal conductivity, and diffuses the heat transmitted from the first heat radiation unit.

Description

TECHNICAL FIELD The present invention relates to a double heat-dissipating sheet, a manufacturing method thereof, and a portable terminal having the same,

More particularly, the present invention relates to a double heat-radiating sheet capable of double-diffusing heat to increase the heat radiation performance and having a heat insulation function for not only heat radiation but also heat, To a portable terminal.

Generally, when an electronic product such as a computer, a display, or a portable terminal can not adequately diffuse the heat generated from the inside to the outside, it causes the occurrence of a screen afterimage due to excessive accumulated heat, a collision with a system failure, May shorten the life of the device or, in severe cases, may cause explosion or fire.

2. Description of the Related Art In recent years, electronic products including portable terminals have been continuously developed, and electronic products have been promoted in terms of high performance and versatility according to the needs of users.

Particularly, in order to maximize the portability and convenience of users, miniaturization and weight reduction are indispensable for a portable terminal, and components integrated in smaller and smaller spaces are mounted for high performance. Accordingly, the parts used in the portable terminal have higher performance and higher heat generation temperature, and the increased heat generation temperature affects the adjacent components, thereby causing a problem of deteriorating the performance of the portable terminal.

Korean Patent Registration No. 10-1134880 discloses a portable terminal including a heat insulating film disposed on the front surface of an LCD, thereby preventing the heat generated from the portable terminal from being transmitted to the user's face through an LCD . However, such a heat insulating film is a low emissivity film which blocks the passage of heat while permitting the maximum transmittance of the visible light ray, and thus can not quickly dissipate the local high temperature generated in the hot spot region of the portable terminal .

Therefore, the inventors of the present invention have been continuously studying a technique capable of excelling in heat dissipation performance to derive the structure and method characteristic of a sheet capable of maximizing heat dissipation performance by doubly diffusing the heat generated in the heat generating portion By inventing, we have completed the present invention which is more economical, usable and competitive.

Korean Patent Registration No. 10-1134880

It is an object of the present invention to provide a double heat-radiating sheet capable of double-diffusing heat generated from a heat-generating portion to improve heat radiation efficiency, a method of manufacturing the same, and a portable terminal having the same.

Another object of the present invention is to provide a double heat-radiating sheet having a heat-insulating function for blocking heat as well as a heat-radiating function, a method of manufacturing the same, and a portable terminal having the same.

According to an aspect of the present invention, there is provided a heat dissipation device including: a first heat dissipation unit having a first heat conductivity and diffusing transmitted heat; And a second heat dissipating unit bonded to the first heat dissipating unit and having a second heat conductivity different from the first heat dissipating rate and diffusing heat transmitted from the first heat dissipating unit.

According to another aspect of the present invention, there is provided a plasma display panel comprising: a first heat dissipation unit made of a first heat dissipation material; And a second heat dissipating unit bonded to the first heat dissipating unit and made of a second heat dissipating material different from the first heat dissipating material.

According to another aspect of the present invention, there is provided a plasma display panel comprising: a first heat dissipation unit made of a first heat dissipation material; A second heat dissipation part stacked on the first heat dissipation part by sputtering, vapor deposition, bonding, or adhesion, and made of a second heat dissipation material different from the first heat dissipation material; And a flaked amorphous sheet laminated on one of the first heat radiation portion and the second heat radiation portion.

According to another aspect of the present invention, there is provided a plasma display panel comprising: a first heat dissipation unit made of a first heat dissipation material; And a second heat dissipation part formed by sputtering or vapor deposition on the first heat dissipation part, the second heat dissipation part being made of a second heat dissipation material different from the first heat dissipation material.

According to another aspect of the present invention, there is provided a method of manufacturing a semiconductor device, comprising: placing a second heat dissipation unit on a first heat dissipation unit; And diffusing the interface between the first heat dissipation unit and the second heat dissipation unit by applying heat and pressure in a vertical direction in the upper portion of the first heat dissipation unit and the lower portion of the second heat dissipation unit, A method of manufacturing a sheet is provided.

In addition, one embodiment of the present invention provides a mobile communication terminal comprising: a terminal body including a circuit board on which an AP chip (application processor chip) is mounted, the terminal body performing a portable terminal function; A display unit exposed on the terminal body; A rear cover detachable from the rear surface of the terminal body; And at least one state of being attached to the back surface of the display unit, a state of shielding the circuit board on which the AP chip is mounted, and a state of being attached to the inner surface of the back cover, The double heat-dissipating sheet has a structure in which a first heat-radiating portion and a second heat-radiating portion having different thermal conductivities are bonded or bonded to each other.

As described above, according to the present invention, there is an advantage that heat dissipation efficiency can be improved by double-diffusing heat generated in the heat-generating portion by being attached to the heat-generating portion, being in contact, or in close proximity.

In the present invention, the first heat-radiating portion and the second heat-radiating portion are joined by diffusion bonding to promote heat transfer from the first heat-radiating portion to the second heat-radiating portion as a bonding layer having intermediate characteristics between the first heat-radiating portion and the second heat- , Heat radiation performance can be increased, and there is an advantage that a process can be reduced because no adhesive is needed.

In the present invention, the porous substrate having a plurality of micropores is laminated on the double heat-radiating sheet to form the micropores of the porous substrate so that the double heat-radiating sheet collects the heat radiated, .

1 is a schematic cross-sectional view of a double heat-radiating sheet according to a first embodiment of the present invention,
2 is a conceptual sectional view for explaining a method for manufacturing a double heat-radiation sheet according to a first embodiment of the present invention,
3 is a conceptual cross-sectional view illustrating a method for manufacturing a double heat-radiation sheet by thermal bonding according to a first embodiment of the present invention,
4 is a cross-sectional view schematically showing a state in which the double heat-radiating sheet according to the first embodiment of the present invention is fixed to the fixing portion,
5 is a schematic cross-sectional view of a double heat-radiating sheet according to a second embodiment of the present invention,
6 is a schematic cross-sectional view of a double heat-radiating sheet according to a third embodiment of the present invention,
7A and 7B are conceptual sectional views for explaining a porous substrate laminated on a double heat radiation sheet according to a third embodiment of the present invention,
8 is a conceptual diagram for explaining that the double heat-radiating sheet according to the present invention is mounted on a portable terminal.

The terms and words used in the present specification and claims should not be construed as limited to ordinary or dictionary terms and the inventor may appropriately define the concept of the term in order to best describe its invention It should be construed as meaning and concept consistent with the technical idea of the present invention.

Therefore, the embodiments described in this specification and the configurations shown in the drawings are merely the most preferred embodiments of the present invention and do not represent all the technical ideas of the present invention. Therefore, It is to be understood that equivalents and modifications are possible.

Hereinafter, the present invention will be described in more detail with reference to the drawings.

1 is a schematic cross-sectional view of a double heat-radiation sheet according to a first embodiment of the present invention.

Referring to FIG. 1, a dual heat-dissipating sheet 100 according to a first embodiment of the present invention includes a first heat-dissipating unit 110 having a first heat-conductivity and diffusing heat transmitted thereto; And a second heat dissipation unit 120 bonded to the first heat dissipation unit 110 and having a second thermal conductivity different from the first thermal conductivity and diffusing heat transmitted from the first heat dissipation unit 110, .

That is, when the first heat is transferred to the first heat dissipation unit 110 of the dual heat dissipation sheet 100, the first heat dissipation unit 110 diffuses the first heat at a first heat conductivity to lower the temperature, When one row is transmitted to the second heat dissipation unit 120, the second heat dissipation unit 120 diffuses the first heat of the second heat conduction rate to lower the temperature to discharge the second heat to the outside.

In the present invention, the first heat dissipating unit 110 is coupled to the heat generating unit in one of attachment, contact, and proximity, and the heat generated in the heat generating unit is transmitted to the first heat dissipating unit 110 and the second heat dissipating unit 120 The heat dissipation efficiency can be improved by double diffusion.

Here, it is preferable that the first heat radiation rate of the first radiation part 110 is lower than the second heat radiation rate of the second radiation part 120.

A bonding layer 115 formed by diffusion bonding is formed between the first and second heat dissipating units 110 and 120.

Referring to the table of thermal conductivity shown in the following Table 1, it is possible to realize a double heat-radiating sheet having a first structure to a third structure that satisfy the relationship between the thermal conductivity of the first heat-dissipating unit 110 and the second heat-dissipating unit 120 .

That is, in the first structure, the first heat-radiating portion 110 is made of one of Al, Mg, and Au, the second heat-radiating portion 120 is made of Cu, and the second structure is formed of the first heat- May be made of Cu, and the second heat-radiating portion 120 may be made of Ag.

matter Thermal conductivity (kcal / mh ° C) Al 175 Mg 244 Au 265 Ag 360 Cu 320

Since graphite has a thermal conductivity approximately twice that of aluminum (Al), graphite has the highest thermal conductivity than Al, Mg, Au, Ag, and Cu so that the first heat- Ag, and Cu, and the second heat-radiating portion 120 is made of graphite.

FIG. 2 is a conceptual sectional view illustrating a method for manufacturing a double heat-radiation sheet according to a first embodiment of the present invention. FIG. 3 is a cross- FIG. 4 is a cross-sectional view schematically showing a state in which the double heat-radiating sheet according to the first embodiment of the present invention is fixed to the fixing portion.

Referring to FIG. 2, in the method of manufacturing a double heat-generating sheet according to the first embodiment of the present invention, the second heat-radiating portion 120 is placed on the first heat-radiating portion 110. Heat and pressure are then applied vertically at the upper portion of the first heat dissipating unit 110 and the lower portion of the second heat dissipating unit 120 to diffuse the interface between the first heat dissipating unit 110 and the second heat dissipating unit 120 bonding sheet to produce a double heat-radiating sheet.

Here, the diffusion bonding is a method of bonding in a solid state by using diffusion of atoms generated on the bonding surface by applying heat and pressure. As a result, thermal stress or deformation after bonding is small, the amount of deformation is small, There is a characteristic that the deterioration of the material caused by the etching is small.

The diffusion bonding applied to the present invention will be described in more detail. When the second heat dissipation unit 120 is brought into close contact with the first heat dissipation unit 110 to heat the material to a temperature below the melting point, The diffusion of atoms generated between the bonding surfaces of the first and second heat dissipating units 110 and 120 is used for joining.

At this time, the bonding strength depends on the pressure, temperature, contact time, and bonding surface state acting on the bonding face.

The atoms of the first heat dissipating unit 110 and the atoms of the second heat dissipating unit 120 are bonded to each other at the bonding surface of the first heat dissipating unit 110 and the second heat dissipating unit 120, The bonding layer has intermediate characteristics between the first heat dissipating unit 110 and the second heat dissipating unit 120 to promote heat transfer from the first heat dissipating unit 110 to the second heat dissipating unit 120, The double heat-radiating sheet of the present invention can improve the heat radiation efficiency.

As shown in FIG. 3, the first heat dissipation unit 110 and the second heat dissipation unit 120 are diffusion-bonded to each other. In this example, the second heat dissipation unit 120 is laminated on the first heat dissipation unit 110 (From the left side to the right side in FIG. 3) between the rollers 251 and 252 and between the rollers 251 and 252, the first heat radiation part 110 and the second heat radiation part 120, which receive heat and pressure between the rollers 251 and 252, Diffusion bonding is performed.

Therefore, in the present invention, since the first and second heat dissipation units are diffusion bonded to each other in a non-adhesive manner, there is an advantage that an adhesive is not necessary and the process can be reduced.

4, when the double heat-radiation sheet 100 is fixed to the fixing portion 300, the first heat-radiation portion 110 of the double-heat-radiation sheet 100 is in contact with, adhered to or close to the heat-generating portion, The second heat radiation portion 120 of the double heat radiation sheet 100 is fixed to the fixing portion 270.

In this case, when the second heat dissipation unit 120 is made of Cu, it is not necessary to form a Ni plating layer on the second heat dissipation unit 120 to prevent oxidation, which may reduce manufacturing costs.

FIG. 5 is a schematic cross-sectional view of a double heat-radiating sheet according to a second embodiment of the present invention, and FIG. 6 is a schematic cross-sectional view of a double heat-radiating sheet according to a third embodiment of the present invention.

Referring to FIG. 5, the double heat-radiation sheet 200 according to the second embodiment of the present invention includes a first heat-radiating portion 210 made of a first heat-radiating material; And a second heat dissipation unit 220 bonded to the first heat dissipation unit 210 and made of a second heat dissipation material different from the first heat dissipation material.

5, the double heat-radiating sheet 200 according to the second embodiment of the present invention is structured such that the heat-radiating portions of the different heat- (Solid phase) adhesive sheet 215 is interposed between the upper and lower sheets 220.

The solid-state adhesive sheet 215 may be one of an acrylic resin, an aramid, a urethane, a polyamide, a polyethylen, an EVA, a polyester, or a PVC. Can be used.

In particular, the solid-state adhesive sheet 215 preferably uses a hot-melt adhesive sheet in a web state or an inorganic ball state in which fibers capable of being thermally adhered are accumulated and have a plurality of pores.

In addition, in the present invention, the second heat radiation portion formed by sputtering or vapor-depositing the double heat radiation sheet on the first heat radiation portion may be laminated. In this case, the double heat-radiating sheet includes a first heat-radiating portion made of a first heat-radiating material; And a second heat dissipation part formed by sputtering or vapor deposition on the first heat dissipation part and made of a second heat dissipation material different from the first heat dissipation material.

Referring to FIG. 6, the double-heat-radiating sheet according to the third embodiment of the present invention can be realized by laminating a porous substrate 330 having a plurality of micropores on the double heat-radiating sheet according to the first and second embodiments. That is, the micro pores of the porous substrate 330 capture the heat that has been released, so that the double-heat-radiation sheet has a heat-insulating function for blocking heat as well as a heat-radiating function.

For example, the porous substrate 330 may be formed by a nano-web having a plurality of pores by an electrospinning method, a nonwoven fabric having a plurality of pores, a polyether sulfone (PES), etc., Any material can be applied if it is possible. Here, it is preferable that the pore size of the porous substrate 330 is less than a maximum of 5 占 퐉 at several tens nm.

When the porous substrate 330 is in the form of a nano-web, a spinning solution is prepared by mixing a polymer material having excellent heat resistance and electrospinning with a solvent at a predetermined ratio, and the spinning solution is electrospun to form nanofibers. Nanofibers are accumulated and formed into a nano web having many pores.

As the diameter of the nanofibers is smaller, the specific surface area of the nanofibers is increased and the ability of the nanofibrous web having a plurality of micropores to collect heat increases, thereby improving the heat insulating performance. Therefore, the diameter of the nanofibers is in the range of 0.3-1.5 μm, and the thickness of the porous substrate 330 is 10-25 μm. The porosity of the pores formed in the porous substrate 330 is preferably in the range of 50 to 80%.

In addition, in the present invention, the amorphous sheet flaked in the double heat-radiating sheet according to the first and second embodiments may be laminated to further add an electromagnetic wave shielding function.

7A and 7B are conceptual sectional views for explaining a porous substrate laminated on a double heat radiation sheet according to a third embodiment of the present invention.

The porous substrate can be used as one of nanofiber webs 332 and 333, nonwoven fabric 331, and laminated structures thereof, which are integrated by nanofibers and have a three-dimensional micropore structure.

The laminated structure of the nanofiber webs 332 and 333 and the nonwoven fabric 331 may be a laminated structure of the nanofibrous web 332 and the nonwoven fabric 331 as shown in Figs. 7A and 7B, 332 / nonwoven fabric 331 / nanofiber web 333 (FIG. 7B). At this time, it is preferable that the thickness t1 of the nanofiber web 332 is thinner than the thickness t2 of the nonwoven fabric 331.

If the porous base material is applied to the laminated structure of the nanofiber web 332 and the nonwoven fabric 331, the nonwoven fabric 331 is less expensive and has a higher strength than the nanofiber web 332, It is possible to reduce the manufacturing cost and improve the strength. In addition, the nonwoven fabric 331 also has a function of collecting heat because a large number of pores exist, thereby performing the role of a heat insulating part.

The nanofibrous web 332 and the nonwoven fabric 331 can be fused due to thermal compression and the melting point of the nanofibrous web 332 is designed to be lower than the melting point of the nonwoven fabric 331, It is preferable that the nanofiber web 332 is melted and fused to the nonwoven fabric 331. For example, when the polymer material for forming the nanofiber web 332 is applied as PVdF, the melting point of the PVdF is 155 ° C., so that the nonwoven fabric 331 is a polyester type having a melting point higher than 155 ° C., A nonwoven fabric 331 made of one of nylon series and cellulosic series is applied.

Therefore, at the time of thermocompression bonding, the region of the nanofiber web 332 in contact with the nonwoven fabric 331 is melted and fused to the nonwoven fabric 331. Here, since the pore size of the nonwoven fabric 331 is much larger than the pore size of the nanoWeb, a part of the molten nanofiber web 332 penetrates into the pores of the nonwoven fabric 331. That is, after the thermocompression bonding is performed with respect to the interface between the nonwoven fabric 331 and the nanofiber web 332 before thermocompression bonding, the nanofiber web 332 melted in the direction of the nanofiber web 332 and in the direction of the non- ) Is spread and distributed. When the degree of melting of the nanofiber web 332 is controlled, the nanofiber web 332 is melted into the pores of the nonwoven fabric 331, and the nano-fiber web 332, which has penetrated into the pores of the nonwoven fabric 331, The fibrous web 332 may be locked to improve adhesion between the nanofiber web 332 and the nonwoven fabric 331.

In the present invention, a polymer substance in which PVdF and PAN are mixed in a ratio of 5: 5 or 6: 4 can be applied as a polymer material forming a nano-web. At this time, the electrospun nanofiber is formed into a structure having a core made of PAN and an outer skin made of PVdF surrounding the core, and the nanofibers having such a structure are laminated to form a nanofiber web 332. When the nanofiber web 332 and the nonwoven fabric 331 having the core and the outer skin structure laminated are thermally compressed, the PVdF of the outer skin is melted and fused to the nonwoven fabric 331.

A release film may be attached to at least one surface of the double heat-radiation sheet of the first to third embodiments of the present invention. In this case, when using the double heat-radiation sheet, the release film is removed before use.

8 is a conceptual diagram for explaining that a double heat-radiating sheet according to the present invention is mounted on a portable terminal.

The double heat-radiating sheet according to the present invention is installed in a portable terminal, and can be used in a heat generating part of a portable terminal (a hot spot area generated by locally concentrated heat due to the operation of the portable terminal, for example, an AP chip (Appication Processor chip) The generated heat is dissipated to minimize the thermal influence applied to the internal parts of the portable terminal by the locally generated high temperature heat and to prevent the heat generated in the heat generating part from leaking to the outside, The heat can be minimized.

Referring to FIG. 8, the portable terminal includes a terminal body including a circuit board on which an AP chip (application processor chip) 52 is mounted, and performs a portable terminal function; A display unit 510 exposed to the terminal body; And a rear cover 530 detachable from the rear surface of the terminal body.

The double heat-radiation sheet of the present invention is in a state of being adhered to the rear surface 511 of the display unit 510, shielding the circuit board on which the AP chip 521 is mounted, 531 in the state of being attached to the portable terminal in at least one state.

At this time, the display unit 510 is exposed to the user through the display unit 510 by being exposed to the external case in the terminal body of the portable terminal. The double heat-radiating sheet of the present invention includes the display unit 510 So that the heat transmitted to the outside can be dissipated.

The double heat radiation sheet of the present invention shields the circuit board on which the AP chip 521 is mounted so that the high heat locally generated in the AP chip 521 can be efficiently dissipated, 531 are adhered to the double heat-radiating sheet of the present invention, heat transmitted to a user gripping the portable terminal can be minimized.

Here, the double heat radiation sheet for shielding the circuit board on which the AP chip 521 is mounted may be mounted on a bracket positioned between the circuit board and the display unit 510.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is clearly understood that the same is by way of illustration and example only and is not to be construed as limited to the embodiments set forth herein. Various changes and modifications may be made by those skilled in the art.

100: double heat-radiating sheet 110, 120, 210, 220:
115: bonding layer 215: solid adhesive sheet
251, 252: roller 270:
330: Porous substrate 331: Nonwoven fabric
332,333: Nano fiber web 510: Display part
521: AP chip 530: rear cover

Claims (20)

A first heat dissipation unit having a first thermal conductivity and diffusing the transmitted heat; And
And a second heat dissipating unit joined to the first heat dissipating unit and having a second thermal conductivity different from the first heat dissipating unit and diffusing heat transmitted from the first heat dissipating unit. The heat sink according to claim 1, wherein the first heat radiation portion has a first thermal conductivity lower than that of the second heat radiation portion, and the first heat radiation portion has a double heat dissipation Sheet. The double heat-radiating sheet according to claim 1, wherein the first heat-radiating portion and the second heat-radiating portion are diffusion bonded, and further includes a bonding layer formed by diffusion bonding between the first heat-radiating portion and the second heat-radiating portion. The double heat-dissipating sheet according to claim 1, wherein the first heat-radiating portion is made of one of Al, Mg, and Au, and the second heat-radiating portion is made of Cu. The double heat-dissipating sheet according to claim 1, wherein the first heat-radiating portion is made of Cu and the second heat-radiating portion is made of Ag. The double heat-dissipating sheet according to claim 1, wherein the first heat-radiating portion is made of one of Al, Mg, Au, Ag, and Cu, and the second heat-radiating portion is made of graphite. The dual heat-dissipating sheet according to claim 1, further comprising a porous substrate having a plurality of micropores formed in the second heat-radiating portion. The dual heat dissipation sheet according to claim 7, wherein the porous substrate is one of a nanofiber web, a nonwoven fabric, and a laminated structure thereof, which are integrated by nanofibers and have a three-dimensional micropore structure. The dual heat-dissipating sheet according to claim 7, wherein the pore size of the porous substrate is less than a maximum of 5 占 퐉 at several tens nm. The double heat-dissipating sheet according to claim 7, wherein porosity of pores formed in the porous substrate is in the range of 50 to 80%. A first heat dissipation part made of a first heat dissipation material; And
And a second heat dissipating part bonded to the first heat dissipating part and made of a second heat dissipating material different from the first heat dissipating material. The double heat-radiating sheet according to claim 11, wherein a thermal conductivity of the first heat-dissipating unit is lower than a thermal conductivity of the second heat-dissipating unit, and the first heat-dissipating unit is attached to the heat-generating unit in one of attachment, contact, and proximity. The double heat-dissipating sheet according to claim 11, wherein a solid-phase adhesive sheet is interposed between the first heat-radiating portion and the second heat-radiating portion. 14. The method of claim 13, wherein the solid adhesive sheet comprises an acrylic resin, an aramid, a urethane, a polyamide, a polyethylen, an EVA, a polyester, a PVC, A dual heat spreading sheet, one of the systems. The double heat-dissipating sheet according to claim 11, wherein the solid adhesive sheet is a hot-melt adhesive sheet in a web state or an inorganic ball state in which fibers capable of being thermally adhered are accumulated and have a plurality of pores. A first heat dissipation part made of a first heat dissipation material;
A second heat dissipation part stacked on the first heat dissipation part by sputtering, vapor deposition, bonding, or adhesion, and made of a second heat dissipation material different from the first heat dissipation material; And
And a flaked amorphous sheet laminated on one of the first heat radiation portion and the second heat radiation portion. A first heat dissipation part made of a first heat dissipation material; And
And a second heat dissipation part formed by sputtering or vapor deposition on the first heat dissipation part, the second heat dissipation part being made of a second heat dissipation material different from the first heat dissipation material. Placing the second heat dissipation part on the first heat dissipation part; And
And applying heat and pressure in a vertical direction at the upper portion of the first heat-radiating portion and the lower portion of the second heat-radiating portion to diffuse bonding the interface between the first heat-radiating portion and the second heat-radiating portion. ≪ / RTI > 19. The method of claim 18,
Wherein the diffusion bonding comprises:
The first and second heat dissipation units are connected to each other by feeding heat to the first and second heat dissipation units in a state after the second heat dissipation unit is placed on the first heat dissipation unit, Wherein the step of forming the double-heat-radiating sheet comprises the steps of: A terminal body including a circuit board on which an AP chip (application processor chip) is mounted, the terminal body performing a portable terminal function;
A display unit exposed on the terminal body;
A rear cover detachable from the rear surface of the terminal body; And
A plurality of the AP chips mounted on the portable terminal in at least one of a state of being attached to the back surface of the display unit, a state of shielding the circuit board on which the AP chip is mounted, And a heat-
Wherein the double heat-radiating sheet has a structure in which the first heat-radiating portion and the second heat-radiating portion having different thermal conductivities are bonded or bonded.

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