JP2009094196A - Heat dissipation structure of portable communication apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide the heat dissipation structure of a portable communication apparatus that easily removes an unpleasant feeling during an operation due to a local rise in case surface temperature without greatly increasing a cost of, for example, adding a special heat dissipation structure to the conventional heat dissipation structure. <P>SOLUTION: A cut hole 5 smaller than the surface size of an electronic component 4 is formed in a graphite sheet 2, and an electronic component surface is brought into contact with the graphite sheet 2 at the periphery of the cut hole 5. Heat conduction to a case 1 is small in the region of the cut hole 5 and heat from the electronic component 4 is easily conducted in peripheral directions thereof so that the heat conduction state in the case is dispersed, thereby preventing a local temperature rise. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a heat dissipation structure for radiating heat from an electronic component in a housing to the outside in a portable communication device such as a mobile phone.

  In mobile communication devices represented by mobile phones, power consumption of electronic components mounted inside the mobile communication device increases with higher functionality and higher performance, resulting in a rise in temperature of the entire device. Yes.

  In an electronic device such as a personal computer, in order to dissipate the heat inside the housing to the outside, a heat sink or fan made of metal for heat dissipation is attached to the surface of the electronic component that generates a large amount of heat.

  For example, in Patent Document 1 (Japanese Patent Laid-Open No. 2002-334958), a heat conductor, a heat conduction plate, and a heat conduction sheet are sequentially interposed between a CPU and a chassis mounted on a substrate, and this heat is applied. A heat dissipating structure is disclosed in which local heat from the CPU is not directly conducted to the chassis by providing a cutout that is retracted from the heat conductor in the conductive sheet.

  Patent Document 2 (Japanese Patent Laid-Open No. 2003-37225) uses a perforated heat conductive sheet having a hole having a shape substantially similar to the outer shape of an electronic component package, and the package is positioned in the hole. In addition, by providing this perforated heat conductive sheet between the wiring board and the heat sink, the electronic component is covered with the perforated heat conductive sheet, and the heat from the electronic component is released to the heat sink through the perforated heat conductive sheet. A cooling structure is disclosed.

  However, recent cellular phones are very small and thin, and due to space limitations, it is difficult to take the above heat dissipation measures similar to those for personal computers.

  In general, in a cellular phone having a small space, a graphite sheet having high thermal conductivity is attached to the inner surface of the casing, and heat from electronic components is diffused by the graphite sheet to prevent a temperature rise.

  FIG. 1 shows a conventional example in which a graphite sheet 2 is attached to the inner surface of a casing 1 of a mobile phone, and the surface of an electronic component 4 mounted on a substrate 3 in the casing 1 is brought into direct contact with the graphite sheet 2 to dissipate heat. It is made into the structure to do.

  In this case, since heat is easily transmitted in the contacting direction and is not easily transmitted to the air, the heat generated by the operation of the electronic component 4 is transmitted to the substrate 3 and the graphite sheet 2 as indicated by an arrow. It is transmitted to the housing 1 through and is radiated to the outside. While the graphite sheet 2 has an effect of diffusing heat, it is easy to conduct heat in the thickness direction, so that the heat that has passed through the graphite sheet 2 locally increases the surface temperature of the housing 1.

FIG. 2 is a conventional example in the case where there is a gap between the electronic component 4 and the graphite sheet 2.
In this case, although the amount of heat transferred to the substrate 3 increases, the heat transfer method does not change, but is transferred to the graphite sheet 2 through the air layer 5 between the electronic component 4 and the graphite sheet 2, and the surface temperature of the housing 1 is locally increased. To be high.

However, in either case of FIG. 1 or FIG. 2, if heat from the surface of the electronic component 4 is immediately transferred to the surface (outer surface) of the housing 1, as shown by the length of the arrow, the housing 1 where the surface temperature of the electronic component 4 is locally high, and if the heat generation of the electronic component is high, the local height of the surface temperature of the housing also increases accordingly, causing uncomfortable feeling during operation. There was a problem.
JP 2002-334958 A JP 2003-37225 A

  The object of the present invention is to easily eliminate the discomfort during operation due to the locally high case surface temperature without causing a significant cost increase such as adding a special heat dissipation mechanism to the conventional heat dissipation structure. An object is to provide a heat dissipation structure for a portable communication device.

  The present invention according to claim 1 is a portable device that dissipates heat from an electronic component mounted on a substrate in a casing of a portable communication device to the outside through a heat conductive sheet attached to the inner surface of the casing and the casing. In the heat dissipation structure of the communication device, a notch that is smaller than the surface size of the electronic component is formed in the heat conductive sheet, and the surface of the electronic component is in contact with the heat conductive sheet around the notch.

  In the invention according to claim 2, in the invention according to claim 1, when a gap is formed between the heat conduction sheet attached to the inner surface of the housing and the surface of the electronic component, the peripheral portion of the surface of the electronic component is The gap between the heat conductive sheet and the heat conductive sheet at that portion is compensated with the heat conductive sheet, thereby contacting the former heat conductive sheet, that is, the heat conductive sheet attached to the inner surface of the housing. To do.

  The invention according to claim 3 is that in the invention according to claim 1 or 2, the space formed between the inner surface of the housing and the surface of the electronic component is filled with the heat insulating material by the cutout opening of the heat conductive sheet. Features.

According to the present invention, the heat from the surface of the electronic component is mainly transmitted from the peripheral portion to the heat conductive sheet and further to the housing, but in the region of the cutout formed in the heat conductive sheet, the heat is transmitted to the housing. Since the heat conduction is weak, that is, the heat from the electronic component is easily transferred to the surrounding direction, the following effects are obtained.
(1) Since the heat transfer state inside the housing can be dispersed and local temperature rise can be prevented, the operation due to the housing surface temperature not locally increasing and the housing surface temperature locally increasing. No discomfort at times.
(2) The temperature of the housing surface can be made uniform.
(3) The housing surface temperature can be lowered without increasing the thickness of the portable communication device.
(4) It becomes possible to use high-performance electronic components.

  According to the invention according to claim 2, even when a gap is formed between the heat conductive sheet attached to the inner surface of the housing and the surface of the electronic component, in addition to the above effects, the periphery of the electronic component This is more effective because the tendency of heat conduction in the direction increases.

  According to the invention of claim 3, since the heat insulating material is filled in the space formed between the inner surface of the housing and the surface of the electronic component by the cutout opening of the heat conductive sheet, the surface of the housing by the electronic component having high heat generation The local rise in temperature can be suppressed by the heat insulating material, and the external force from the housing is evenly applied to the electronic component, so that the connection reliability of the electronic component can be improved.

  Next, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 3 is a cross-sectional view showing the heat dissipation structure of Example 1 of the present invention.
A graphite sheet 2, which is a heat conductive sheet having a high thermal conductivity, is attached to the inner surface of the casing 1 of the portable communication device. A substrate 3 is disposed inside the housing 1, and an electronic component 4 is mounted on the substrate 3.

  The graphite sheet 2 is formed with a notch 5 slightly smaller than the surface size of the electronic component 4, and only the peripheral portion of the surface of the electronic component 4 is in contact with the heat conductive sheet 2 around the notch 5. In addition, a space (air layer) is formed between the surface of the electronic component 4 and the inner surface of the housing 1 by the notch 5.

FIG. 4 shows heat transfer by arrows according to the structure of the first embodiment.
The heat generated by the operation of the electronic component 4 is transmitted to the substrate 3 and the graphite sheet 2, but a notch 5 is formed in the graphite sheet 2, and the surface of the electronic component 4 is in contact with the graphite sheet 2 around it. Therefore, heat is easily transmitted in the direction around the electronic component 4, and the surface temperature of the housing 1 does not become a temperature distribution in which the location where the electronic component 4 exists is locally increased.

This utilizes the property that heat is easily transmitted to a member having high thermal conductivity and is difficult to be transmitted to a low member.
By adopting such a structure, the surface temperature of the housing 1 is made uniform, so that problems such as discomfort during operation can be solved.

FIG. 5 is a cross-sectional view showing a heat dissipation structure of Example 2 of the present invention.
Example 2 is a case where there is a gap between the electrical component 4 and the graphite sheet 2, and the peripheral portion of the surface of the electronic component 4 is defined as a gap between the graphite sheet 2 and the graphite sheet 2 a. It is in the state which contact | abutted with the graphite sheet 2 by partially supplementing with. The graphite sheet 2 a may be integrated with the graphite sheet 2.

  If it does in this way, since it becomes easier to diffuse the heat | fever from the electrical component 4 to the circumference | surroundings, it becomes possible to reduce the local surface temperature rise in the location where the electrical component 4 exists.

  In both cases of Example 1 and Example 2, when the space (air layer) formed by the notch 5 of the graphite sheet 2 is filled (including the case where it is fitted), the housing by the electronic component 4 is used. The local rise in the body surface temperature can be suppressed by the heat insulating material, and the electrical component 4 receives the external force from the housing 1 evenly, so that the connection reliability of the electrical component 4 can be improved. .

It is sectional drawing which shows how to transmit the heat in the prior art example with no clearance gap between an electronic component and a graphite sheet. It is sectional drawing which shows how to transmit the heat | fever in the prior art example with a clearance gap between an electronic component and a graphite sheet. It is sectional drawing which shows the thermal radiation structure of Example 1 of this invention. It is sectional drawing which shows how to transmit the heat in the same as the above. It is sectional drawing which shows how to transmit the heat | fever in the thermal radiation structure of Example 2 of this invention.

Explanation of symbols

1 Housing 2, 2a Graphite sheet 3 Substrate 4 Electronic component 5 Notch

Claims (3)

  In the heat dissipating structure of the portable communication device that dissipates heat from the electronic components mounted on the substrate in the case of the portable communication device to the outside through the heat conduction sheet attached to the inner surface of the case and the case, the heat A heat dissipation structure for a portable communication device, wherein a cutout opening smaller than a surface size of the electronic component is formed in the conductive sheet, and the surface of the electronic component is in contact with the heat conductive sheet around the cutout opening.   A gap is formed between the heat conduction sheet provided on the inner surface of the housing and the surface of the electronic component, and the peripheral edge portion of the surface of the electronic component is filled with the heat conduction sheet at that portion. The heat dissipation structure for a portable communication device according to claim 1, wherein the heat dissipation sheet is in contact with the heat conductive sheet.   The heat dissipation structure for a portable communication device according to claim 1 or 2, wherein a heat insulating material is filled in a space formed between the inner surface of the housing and the surface of the electronic component by the cutout opening of the heat conductive sheet.

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