JP6232582B2 - Thermal insulation sheet and heat countermeasure structure using the same - Google Patents

Description

  The present invention relates to a heat shielding sheet used for smartphones, tablet terminals, and the like.

  In recent years, with further improvement in performance of portable devices, the amount of heat generated in the devices has become very large. When this calorific value becomes large, the temperature of the casing rises, which may cause discomfort to the user and cause burns. Therefore, as shown in FIG. 3, a configuration has been proposed in which the heat diffusion sheet 2 is brought into contact with the heat-generating component 1 mounted on the substrate 4 and heat is released to the housing 3.

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

Japanese Patent Laid-Open No. 10-229287

  In the above conventional configuration, heat is spread by the heat diffusion sheet, but when viewed from the housing side, the temperature distribution spreads around the heat generating component. When touching the housing, it does not feel so uncomfortable even if the overall temperature is slightly higher, but it becomes easier to feel uncomfortable if it is partially higher.

  In view of this problem, the present invention has an object to provide a heat shield sheet that has a small temperature distribution on the housing even when heat is generated in the heat generating component, and makes it difficult to feel discomfort.

  In order to solve the above-mentioned problems, the present invention forms a protective film on the first surface of the graphite sheet, and an infrared reflection film via an adhesive layer on the second surface opposite to the first surface of the graphite sheet. Then, a heat insulating sheet is formed by further forming a heat insulating layer thereon.

  With the above configuration, the heat generated in the heat generating component is transmitted to the graphite sheet and diffused in the surface direction. However, the temperature of the graphite sheet is highest at the part facing the heat-generating component, and infrared rays are radiated from the graphite sheet according to the temperature, so that the infrared rays are transmitted to the case and a temperature difference is felt on the case surface. End up. On the other hand, in the present invention, since the infrared reflecting film is formed on the surface of the graphite sheet opposite to the heat generating component via the adhesive layer, the infrared rays radiated from the graphite sheet are reflected toward the graphite sheet. Therefore, the temperature of the housing can be prevented from rising locally by the infrared rays.

Sectional drawing of the electronic device using the heat insulation sheet in one embodiment of this invention The top view inside the electronic device using the heat insulation sheet in one embodiment of the present invention Cross-sectional view of conventional electronic equipment

  Hereinafter, a heat shielding 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 an electronic apparatus using a heat shield sheet according to an embodiment of the present invention. A substrate 11 on which a heat generating component such as an IC is mounted is housed in a housing 18, and a heat shielding sheet is adhered to the inside of the housing 18 at a position facing the heat generating component 12 with a space therebetween. Has been. The heat shielding sheet is formed by laminating a protective film 13, a graphite sheet 14, an adhesive layer 15, an infrared reflective film 16, and a heat insulating layer 17 from the heat generating component side.

  The protective film 13 is a polyethylene terephthalate (PET) film coated with an acrylic adhesive and has a thickness of about 10 μm. The graphite sheet 14 uses a pyrolytic graphite film excellent in thermal conductivity, and has a thickness of about 25 μm. The adhesive layer 15 is composed of a double-sided tape having a thickness of about 30 μm and an acrylic adhesive applied to both sides of the PET film. An aluminum foil having a thickness of about 5 μm is used for the infrared reflecting film 16. Here, the infrared reflection film 16 refers to a film having an infrared emissivity with a wavelength of 10 μm of 0.1 or less. The infrared reflective film 16 may be a foil or tape-like one, or may be obtained by vapor deposition on a resin sheet.

  Further, a non-woven fabric or foam resin having a thickness of about 100 μm is used for the heat insulating layer 17 so that the thermal conductivity is lower than that of the protective film 13 and the adhesive layer 15. Furthermore, it is desirable to make the thickness of the heat insulating layer 17 thicker than the thickness of the adhesive layer 15. An acrylic pressure-sensitive adhesive is applied to both surfaces of the heat insulating layer 17 so that it can be adhered to the infrared reflecting film or the casing.

  With the configuration described above, the heat generated by the heat generating component 12 is transmitted to the housing 18 side by heat conduction through the air and infrared rays radiated from the surface of the heat generating component. The heat transmitted through the air is transmitted to the graphite sheet 14 through the protective film 13. The heat transmitted to the graphite sheet 14 spreads in the surface direction of the graphite sheet 14. On the other hand, the infrared rays radiated from the surface of the heat generating component 12 are absorbed by the protective film 13 and the graphite sheet 14 and converted to heat. Although the heat transmitted to the graphite sheet 14 is diffused in the surface direction, the graphite sheet 14 also has a heat distribution centering on the portion facing the heat generating component 12. If the graphite sheet 14 has a heat distribution, infrared rays are radiated from the graphite sheet 14 in accordance with the heat distribution. As a result, the heat distribution also remains on the housing 18.

  In contrast, in the present embodiment, since the infrared reflecting film 16 is provided on the graphite sheet 14 via the adhesive layer 15, the infrared radiation radiated from the graphite sheet 14 is reflected to the heat generating component 12 side. Therefore, although the heat distribution of the graphite sheet 14 remains due to heat conduction, the influence due to infrared radiation can be avoided. Furthermore, since the heat insulation layer 17 is formed on the infrared reflective film 16, the heat distribution in the housing 18 can be made small.

  If the thermal conductivity of the adhesive layer 15 is too good, more heat is transmitted by the thermal conduction of the adhesive layer 15 than by infrared radiation, so that the effect of the infrared reflective film 16 is less likely to occur. Therefore, it is desirable that the thermal conductivity of the adhesive layer 15 is 0.3 W / m · K or less.

  Further, even if the adhesive layer 15 becomes too thin, it is difficult to obtain the effect of the infrared reflecting film 16, and therefore the thickness is desirably 10 μm or more. However, even if it is thicker than a certain thickness, the effect is not changed, and the entire thickness is only too thick. Here, the thickness of the adhesive layer 15 means all the thicknesses sandwiched between the graphite sheet 14 and the infrared reflection film 16.

  Even with the configuration described above, a temperature distribution may still remain around the heat generating component. FIG. 2 is a top view of the inside of the electronic device using the heat shield sheet according to the embodiment of the present invention. Here, the size of the heat generating component 12 is about 5 mm × 5 mm, the size of the graphite sheet 14 is about 30 mm × 30 mm, and the size of the infrared reflecting film 16 is about 10 mm × 10 mm, as viewed from above. Sometimes the heat generating component 12 is completely covered. The infrared reflection film 16 is disposed so as to completely overlap the inside of the graphite sheet 14 when viewed from above. In this way, the size of the infrared reflective film 16 is larger than the size of the heat generating component 12 and smaller than the size of the graphite sheet 14, and the heat generating component 12 having the highest temperature is configured by overlapping each other. In the case 18 above the infrared ray, infrared rays are reflected by the infrared reflection film 16 so that the temperature rise is suppressed, and the temperature rises a little in the area where there is no infrared reflection film 16, so that the temperature distribution as a whole is made smaller. Can do.

  In order to obtain the above effects, it is desirable that the size of one side of the infrared reflective film 16 is two to four times the size of the heat generating component 12.

  In addition, it is more preferable to form a double-sided tape or the like on the heat insulating layer 17 and to attach the tape to the inside of the housing because the assembly of the device can be simplified.

  The heat shielding sheet according to the present invention is industrially useful because even if heat is generated by the heat-generating component, the temperature distribution on the housing is small and uncomfortable feeling can be hardly felt.

DESCRIPTION OF SYMBOLS 11 Board | substrate 12 Heat-emitting component 13 Protective film 14 Graphite sheet 15 Adhesion layer 16 Infrared reflective film 17 Heat insulation layer 18 Case

Claims (3)

A protective film is formed on the first surface of the graphite sheet, an infrared reflecting film is formed on the second surface opposite to the first surface of the graphite sheet via an adhesive layer, and heat insulation is further formed thereon. A heat shielding sheet , wherein a layer is formed and the size of the infrared reflecting film is smaller than the size of the graphite sheet. The heat countermeasure structure according to claim 1, wherein the first surface side of the heat shielding sheet according to claim 1 is opposed to a heat-generating component, and the second surface side is bonded to a housing. 3. The heat countermeasure structure according to claim 2, wherein the size of the infrared reflecting film is larger than the size of the heat generating component and smaller than the size of the graphite sheet.

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