JP2015216184A - Heat transport sheet and heat dissipation structure using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heat transport sheet capable of efficiently transporting heat to a desired position without releasing the heat on the way thereto.SOLUTION: The heat transport sheet includes: a laminated sheet 14 including plural graphite sheets 11 being laminated each other; and a heat insulation layer 17 covering the laminated sheet 14 in an area excluding one end portion 15 of the laminated sheet 14 and the other end part 16 at the opposite side to the one end portion 15 of the laminated sheet 14. By using the heat transport sheet, even when a heat generating component and a secondary battery are disposed close to each other, the temperature difference on the secondary battery is reduced.

Description

  The present invention relates to a heat transport sheet used for an electronic device having a heat generating component inside a smartphone, a tablet terminal or the like, and a heat dissipation structure using the heat transport sheet.

  In recent years, with the improvement in performance of various electronic devices, the amount of heat generated inside the device has increased, and measures against this heat have become necessary. Therefore, as shown in FIG. 3, the heat generated in the heat generating component 1 is diffused and radiated by the heat conductive sheet 2.

  As prior art document information related to the invention of this application, for example, Patent Document 1 is known.

JP 2013-242904 A

  However, when the amount of heat generated from the heat generating component increases, the temperature in the vicinity of the heat generating component tends to increase particularly due to heat radiation from the heat conductive sheet or the heat generating component. On the other hand, since the power consumption is increased, the secondary battery used in the electronic device is also enlarged, and the distance between the heat generating component and the secondary battery is reduced. For this reason, the temperature becomes high at a portion close to the heat generating component of the secondary battery. When a temperature difference occurs in the secondary battery, problems such as shortening the life of the secondary battery occur. The present invention can efficiently diffuse the heat generated inside the device and suppress the deterioration of the secondary battery by reducing the temperature difference in the secondary battery.

  In order to solve the above problems, the present invention provides a laminated sheet in which graphite sheets are laminated, and a heat insulating layer that covers the laminated sheet in a region other than one end of the laminated sheet and the other end opposite to the one end of the laminated sheet. And a configuration having the above.

  As described above, the heat transport amount can be increased by laminating the graphite sheets, and the laminated sheet other than the one end and the other end is covered with the heat insulating layer, so that heat is applied from one end to the other end. It is possible to prevent heat dissipation while carrying. By comprising in this way, it can prevent heat radiating on the way and can obtain the heat-transport sheet | seat which conveys heat efficiently to a required place, Thereby, the temperature rise of a heat-emitting component vicinity can be suppressed.

Sectional drawing of the heat-transport sheet | seat in one embodiment of this invention Sectional drawing of the electronic device using the heat transport sheet in one embodiment of this invention Sectional view of an electronic device using a conventional heat conductive sheet

  Hereinafter, a heat transport sheet according to an embodiment of the present invention will be described with reference to the drawings.

  FIG. 1 is a cross-sectional view of a heat transport sheet according to an embodiment of the present invention, in which three pyrolytic graphite sheets 11 having a thickness of about 25 μm are bonded together through an adhesive layer 12, and a thickness of about An insulating layer 13 made of 10 μm polyethylene terephthalate (hereinafter referred to as “PET”) is bonded to form a laminated sheet 14. Here, the adhesive layer 12 may be a double-sided tape or may simply be coated with an adhesive. Further, a region excluding one end 15 and the other end 16 of the laminated sheet 14 is covered with a heat insulating layer 17. As the heat insulation layer 17, a layer having a thickness of about 100 [mu] m and impregnated with silica by impregnating a nonwoven fabric with silica is used. The thermal conductivity in the surface direction of the pyrolytic graphite sheet 11 is about 1600 W / m · K, and the thermal conductivity of the heat insulating layer 17 is about 0.03 W / m · K. The thermal conductivity of the heat insulating layer 17 is desirably 0.2 W / m · K or less, and more desirably 0.1 W / m · K or less.

  In this way, the heat transport sheet is configured, for example, one end 15 where the laminated sheet 14 is exposed is thermally connected to the heat generating component 19, and the other end 16 where the laminated sheet 14 is exposed is thermally connected to the heat sink portion 22. By doing so, heat can be carried efficiently.

  Furthermore, it is desirable to provide the infrared reflecting layer 18 on the heat insulating layer 17. The graphite sheet 11 is easy to radiate the transmitted heat as infrared rays. Therefore, even if the heat insulating layer 17 is present, the energy converted into infrared rays easily escapes due to radiation. Therefore, by providing the infrared reflecting layer 18 on the heat insulating layer 17, the infrared rays emitted from the heat conductive sheet can be reflected so as not to escape to the outside. Here, the infrared reflection layer 18 refers to a layer having an infrared emissivity of a wavelength of 10 μm of 0.1 or less. For example, an aluminum foil or a PET tape with a metal such as aluminum deposited thereon can be used. By reducing the unevenness of the surface, the infrared emissivity can be reduced. By comprising as mentioned above, the heat transport sheet which can carry heat efficiently from the one end part 15 to the other end part 16 can be obtained.

  In FIG. 1, the one end 15 and the other end 16 where the laminated sheet 14 is exposed are provided on the same surface of the laminated sheet 14, but they may be different surfaces. Moreover, both sides may be exposed.

  Next, a heat dissipation structure using the heat transport sheet in one embodiment of the present invention will be described.

  FIG. 2 is a cross-sectional view of an electronic device using a heat transport sheet according to an embodiment of the present invention, in which one end portion 15 of the laminated sheet 14 is thermally connected to a heat-generating component 19 made of an IC. The other end 16 is thermally connected to the secondary battery 20. The other end 16 is thermally connected to a region 21 farther from the heat generating component 19 than half of the region of the secondary battery 20.

  The laminated sheet 14 is formed by bonding three pyrolytic graphite sheets 11 having a thickness of about 25 μm through an adhesive layer 12 and bonding insulating layers 13 made of PET having a thickness of about 10 μm on the upper and lower surfaces thereof. ing. Further, a region excluding one end 15 and the other end 16 of the laminated sheet 14 is covered with a heat insulating layer 17. As the heat insulation layer 17, a layer having a thickness of about 100 [mu] m and impregnated with silica by impregnating a nonwoven fabric with silica is used. The thermal conductivity in the surface direction of the pyrolytic graphite sheet 11 is about 1600 W / m · K, and the thermal conductivity of the heat insulating layer 17 is about 0.03 W / m · K. The thermal conductivity of the heat insulating layer 17 is desirably 0.2 W / m · K or less, and more desirably 0.1 W / m · K or less.

  When the position of the secondary battery 20 is disposed near the heat generating component 19, the heat from the heat generating component 19 is easily transmitted directly to the secondary battery 20. Therefore, a portion close to the heat generating component 19 in the secondary battery 20 is likely to become high temperature. Thus, when a temperature difference occurs in the secondary battery 20, problems such as shortening the life of the secondary battery 20 arise. In the configuration of the present embodiment, the heat transport sheet is covered with the heat insulating layer 17 and is thermally connected to the region 21 farther from the heat generating component 19 than half of the region of the secondary battery 20. The temperature difference in the inside can be reduced.

  In the above embodiment, the other end 16 of the laminated sheet 14 is thermally connected to the secondary battery 20. For example, it is thermally connected to a shield plate or the like facing the secondary battery 20. It doesn't matter. Even in this case, it is important to thermally connect to the region 21 farther from the heat generating component 19 than half of the region of the secondary battery 20.

  Furthermore, it is desirable to provide the infrared reflecting layer 18 on the heat insulating layer 17. The graphite sheet 11 is easy to radiate the transmitted heat as infrared rays. Therefore, even if the heat insulating layer 17 is present, the energy converted into infrared rays easily escapes due to radiation. Therefore, by providing the infrared reflecting layer 18 on the heat insulating layer 17, the infrared rays emitted from the heat conductive sheet can be reflected so as not to escape to the outside. Here, the infrared reflection layer 18 refers to a layer having an infrared emissivity of a wavelength of 10 μm of 0.1 or less. For example, an aluminum foil or a PET tape with a metal such as aluminum deposited thereon can be used. By reducing the unevenness of the surface, the infrared emissivity can be reduced.

  In the above-described embodiment, the laminated sheet 14 is a laminate of a plurality of graphite sheets 11, but may be a stack of sheets obtained by folding a single graphite sheet.

  The heat transport sheet according to the present invention and the heat dissipation structure using the same prevent secondary heat dissipation, efficiently carry heat to a necessary place, and reduce the temperature difference in the secondary battery, thereby reducing the secondary battery. This is industrially useful.

DESCRIPTION OF SYMBOLS 11 Graphite sheet 12 Adhesive layer 13 Insulating layer 14 Laminated sheet 15 One end part 16 Other end part 17 Heat insulation layer 18 Infrared reflective layer 19 Heating component 20 Secondary battery 21 Area | region 22 far from a heat-generating component rather than half of the area | region which provided the battery Part

Claims (6)

A heat transport sheet comprising: a laminated sheet obtained by laminating graphite sheets; and a heat insulating layer that covers the laminated sheet in a region other than one end of the laminated sheet and the other end opposite to the one end of the laminated sheet. . The heat transport sheet according to claim 1, wherein an infrared reflective layer is formed on the heat insulating layer. The heat transport sheet according to claim 1, wherein a sheet having a thermal conductivity of 0.2 W / m · K or less is used for the heat insulating layer. The heat transport sheet according to claim 3, wherein a sheet in which a nonwoven fabric is impregnated with silica is used for the heat insulating layer. One end of the laminated sheet laminated with the graphite sheet is thermally connected to the heat generating component, and the other end of the laminated sheet opposite to the one end is separated from the heat generating component more than half of the region where the battery is provided. A heat dissipation structure that is thermally connected to a distant region and covers the laminated sheet other than the one end and the other end with a heat insulating layer. The heat dissipation structure according to claim 5, wherein an infrared reflecting layer is formed on the heat insulating layer.

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