Heat transfer device and electronic apparatus

The present invention relates to a heat transport device for transporting heat of a heating element and an electronic device including the heat transport device.

An electronic device may be provided with a heating element such as a CPU, and it is necessary to dissipate the heat of the heating element. Patent Document 1 discloses an invention in which heat generated by a computer CPU is transported by a heat pipe and further transported by a heat spreader to dissipate heat. In the present invention, the heat pipe is in contact with the CPU and the heat spreader is in contact with the heat pipe.

<p><patcit num="1"><text>Japanese Unexamined Patent Publication No. 2000-349479</text></patcit></p>

<p> For example, electronic devices such as notebook PCs are becoming thinner and lighter, and it is desired to appropriately dissipate heat from heating elements such as CPUs. In the invention described in Patent Document 1, the CPU, the heat pipe, and the heat spreader are laminated in the thickness direction in the housing of the computer, and it is difficult to reduce the thickness.</p><p> Examples of the combination of the heat pipe and the heat spreader include heat transport devices 500A, 500B and 500C as shown in FIG. 8 in addition to the invention described in Patent Document 1. The heat transport device 500A shown in FIG. 8A includes a heat pipe 502 and a heat spreader 504a. The heat receiving surface 506 of the heat pipe 502 is in contact with the CPU 508, which is a heating element. CPU 508 is mounted on board 510. The heat spreader 504a is fixed to the side surface 512 orthogonal to the heat receiving surface 506 in the heat pipe 502 to transfer heat. The heat pipe 502 and the heat spreader 504a have the same thickness. In such a heat transport device 500A, the weight increases due to the thickness of the heat spreader 504a. Further, although the design contact area between the heat pipe 502 and the heat spreader 504a is large, there is a concern that good heat transfer characteristics cannot be obtained if the actual contact between the two is insufficient.</p><p> The heat transport device 500B shown in FIG. 8 (b) includes a heat pipe 502 and a heat spreader 504b. The heat spreader 504b is fixed to the side surface 512 to transfer heat. The heat spreader 504b is thinner than the heat pipe 502. In such a heat transport device 500B, the heat spreader 504b is thin and therefore lightweight, but there is a concern that the heat transfer characteristics and mechanical strength will be insufficient due to the small contact area between the heat pipe 502 and the heat spreader 504b.</p><p> The heat transport device 500C shown in FIG. 8 (c) includes a heat pipe 502 and a heat spreader 504c. The heat spreader 504c is fixed to the facing surface 514 on the heat pipe 502 opposite to the heat receiving surface 506. In this heat transport device 500C, the CPU 508, the heat pipe 502, and the heat spreader 504c are laminated in the thickness direction. Although it is possible to set the heat spreader 504c to be appropriately thin, further thinning is desired.</p><p> The present invention has been made in view of the above problems, and an object of the present invention is to provide a heat transport device and an electronic device which are thin, lightweight, and have excellent heat transfer characteristics.</p>

<p> In order to solve the above-mentioned problems and achieve the object, the heat transport device according to the first aspect of the present invention includes a heat pipe that is thermally connected to a heating element and a heat spreader that is thermally connected to the heat pipe to dissipate heat. A heat transport device comprising the above, wherein the heat pipe has a heat receiving surface that receives heat from the heating element and a side surface that intersects the heat receiving surface, and the heat spreader surrounds the heat pipe. The first plate member is provided so as to surround the first plate member and the side surfaces of the first plate member are thermally connected to each other, and the side surface of the first plate member opposite to the side surface in contact with the heat pipe. And a second plate member whose side surfaces are thermally connected to each other, and the second plate member is thinner than the first plate member.</p><p> The first plate member and the second plate member may have a connecting plane formed on the same plane as the facing surface of the heat pipe opposite to the heat receiving surface.</p><p> It may have a heat transfer material that comes into contact with the connecting plane of the first plate member, the connecting plane of the second plate member, and the facing surface of the heat pipe.</p><p> The heat transfer material may be a housing of an electronic device provided with the heat transfer device.</p><p> The heat transfer material may be a metal film provided on the inner surface of the housing of the electronic device provided with the heat transfer device.</p><p> The first plate member and the second plate member may be press-fitted at a plurality of meshing portions with each other.</p><p> The electronic device according to the second aspect of the present invention includes the above heat transport device and the heating element.</p><p> The electronic device according to the third aspect of the present invention is an electronic device including a heating element, a heat transport device for transporting the heat of the heating element, and a housing provided with the heating element and the heat transport device. The heat transport device includes a heat pipe that is thermally connected to the heating element and a heat spreader that is thermally connected to the heat pipe to dissipate heat, and the heat pipe receives heat from the heating element. It has a surface and a side surface that intersects the heat receiving surface, and the heat spreader is provided so as to surround the heat pipe, and the heat pipe and the side surfaces are thermally connected to each other and the heat receiving surface of the heat pipe. Has a connecting plane formed on the same plane with respect to the opposing surfaces on the opposite side, and the housing contacts the connecting plane of the heat spreader and the facing surface of the heat pipe.</p>

<p> According to the above aspect of the present invention, since the heat pipe and the spreader do not overlap in the thickness direction, they can be made thinner. Moreover, since the second plate member is thinner than the first plate member, the weight can be reduced. Further, the first plate member is thicker than the second plate member, a large contact area with the heat pipe can be secured, and the heat transfer characteristics are excellent.</p>

<figref num="1">FIG. 1 is a perspective view showing a state in which the electronic device according to the embodiment is closed and stored.</figref><figref num="2">FIG. 2 is a perspective view schematically showing a state in which the electronic device shown in FIG. 1 is opened and used.</figref><figref num="3">FIG. 3 is a plan view schematically showing the internal structure of the electronic device shown in FIG.</figref><figref num="4">FIG. 4 is an exploded perspective view of the housing member and the elements provided inside the housing member.</figref><figref num="5">FIG. 5 is a cross-sectional side view of a housing member in an electronic device.</figref><figref num="6">FIG. 6 is a view showing a modified example of the heat transport device, (a) is a cross-sectional side view of the heat transport device according to the first modified example, and (b) is a cross-sectional side view of the heat transport device according to the second modified example. It is a cross-sectional side view, (c) is a cross-sectional side view of the heat transport device according to the third modification, and (d) is a cross-sectional side view of the heat transport device according to the fourth modification.</figref><figref num="7">FIG. 7 is a plan view of the heat transport device according to the fifth modification.</figref><figref num="8">FIG. 8 is a view showing a heat transport device according to a comparative example, (a) is a cross-sectional side view of the first example, (b) is a cross-sectional side view of the second example, and (c). Is a cross-sectional side view of the third example.</figref>

Hereinafter, embodiments of the heat transport device and the electronic device according to the present invention will be described in detail with reference to the drawings. The present invention is not limited to this embodiment.

FIG. 1 is a perspective view showing a state in which the electronic device 10 according to the embodiment is closed and stored. FIG. 2 is a perspective view schematically showing a state in which the electronic device 10 shown in FIG. 1 is opened and used. FIG. 3 is a plan view schematically showing the internal structure of the electronic device 10 shown in FIG. The electronic device 10 includes a heat transport device 11 according to an embodiment inside.

As shown in FIGS. 1 and 2, the electronic device 10 includes two housing members 12A and 12B, a spine member 14, and a display 16. The housing members 12A and 12B are covered with a cover 18. The cover 18 is, for example, polyurethane. In this embodiment, a tablet PC that can be folded in half like a book is illustrated as an electronic device 10. The electronic device 10 may be a mobile phone, a smartphone, an electronic notebook, or the like.

The display 16 is, for example, a touch panel type liquid crystal display. The display 16 has a structure that can be folded together when the housing members 12A and 12B are folded. The display 16 is, for example, a flexible display such as an organic EL (Electro Luminescence) having a highly flexible paper structure, and opens and closes as the housing members 12A and 12B are opened and closed.

Each of the housing members 12A and 12B is a rectangular plate-shaped member having side walls standing upright on three sides other than the side corresponding to the spine member 14. Each housing member 12A and 12B is composed of, for example, a metal plate such as stainless steel, magnesium or aluminum, or a fiber reinforced resin plate containing reinforcing fibers such as carbon fiber. The display 16 is fixed to the inner surface side of the housing members 12A and 12B via a support plate. The housing members 12A and 12B are connected via a pair of hinge mechanisms 19 and 19. The hinge mechanism 19 foldably connects the housing members 12A and 12B to the storage form shown in FIG. 1 and the usage form shown in FIG. The line O shown by the alternate long and short dash line in FIG. 3 indicates the bending center O which is the center of the folding operation of the housing members 12A and 12B.

As shown in FIG. 3, a heat transport device 11, a rectangular main board 20, a communication module 22, an SSD (Solid State Drive) 24, and the like are mounted and fixed to the inner surface 12Aa of the housing member 12A. The heat transport device 11 is arranged between the main substrate 20 and the inner surface 12Aa (see FIG. 4). In FIG. 3, only the outline of the main substrate 20 on the front side is shown by a virtual line so that the heat transport device 11 can be easily visually recognized. The main substrate 20 and the heat transport device 11 occupy a large area on the inner surface 12Aa of the housing member 12A. A cooling fan 26 is provided at a corner of the housing member 12A. The sub-board 28, the antenna 30, the battery device 32, and the like are attached and fixed to the inner surface 12Ba of the housing member 12B.

FIG. 4 is an exploded perspective view of the housing member 12A and the elements provided inside the housing member 12A. In the following description, the direction in which the main board 20 is arranged in FIG. 4 is upward, and the direction in which the housing member 12A is arranged is downward.

As shown in FIG. 4, a CPU (Central Processing Unit) 34, a memory 36, and the like are mounted on the lower surface of the main board 20. The CPU 34 is a heating element having the largest amount of heat among the electronic components mounted on the electronic device 10.

The heat transport device 11 is a component that transports and dissipates heat from the CPU 34, and includes a heat pipe 38 that is thermally connected to the CPU 34 and a heat spreader 40 that is thermally connected to the heat pipe 38 to dissipate heat. The heat transport device 11 is set to have the same size as or slightly larger than the main substrate 20 in a plan view.

The heat pipe 38 has a configuration in which, for example, a metal pipe having both ends joined to form a closed space inside is crushed, and heat is efficiently transported by utilizing the phase change of the working fluid sealed in the closed space. It is a possible heat transport device. The heat pipe 38 is arranged so that a part of the heat pipe 38 is in contact with the CPU 34, and the end 39 is connected to the cooling fan 26 connected to the air outlet of the cooling fan 26 so as to transfer heat. The cooling fan 26 is arranged in the vicinity of the end 39, and takes in air from one of the air vents 42a on one side of the housing member 12A and the air vents 42b on the other side and exhausts it to the other, and heats the heat pipe 38. Is released.

The heat spreader 40 includes a first plate member 44 that is fixed so as to surround a portion of the heat pipe 38 other than the end portion 39, and a second plate member that is further surrounded and fixed to substantially the entire circumference of the first plate member 44. Has 46 and. The heat pipe 38 and the first plate member 44 have the same thickness. The second plate member 46 is thinner than the first plate member 44. The side of the heat spreader 40 on the side where the end 39 is arranged is formed substantially of only the first plate member 44. Since the first plate member 44 is thicker than the second plate member 46, the protruding end portion 39 can be stably supported. The heat pipe 38, the first plate member 44, and the second plate member 46 extend along the inner surface 12Aa and do not overlap in the vertical direction. The first plate member 44 has an area equal to or larger than that of the heat pipe 38. The second plate member 46 has a larger area than the first plate member 44.

The heat pipe 38 and the first plate member 44 are fixed and in contact with each other by, for example, pressing or press fitting. In the press fitting of the heat pipe 38 and the first plate member 44, for example, the metal pipe and the base material of the first plate member 44 are simultaneously pressurized by the rolling of a roller, and the metal pipe is crushed to form the heat pipe 38. At the same time, the first plate member 44 can be press-fitted into the side surface thereof.

The first plate member 44 and the second plate member 46 are fixed and in contact with each other by, for example, pressing or press fitting. The boundary between the first plate member 44 and the second plate member 46 is formed with a comb-teeth-shaped meshing portion 48 continuously provided over substantially the entire circumference. The contact area between the first plate member 44 and the second plate member 46 is widened by mutual engagement by the meshing portion 48, and the mechanical connection strength and thermal conductivity are improved. A notch 50 is formed in the corner of the second plate member 46 to avoid the cooling fan 26.

The heat spreader 40 is a highly heat-conducting metal plate, such as aluminum, copper, stainless steel or an alloy thereof. The first plate member 44 and the second plate member 46 may be made of the same material or different materials.

A part of the heat pipe 38 comes into contact with the CPU 34 and extends in both width directions to transfer heat to the heat spreader 40 and the cooling fan 26. The heat spreader 40 has a sufficiently large area, and by receiving heat from the CPU 34 and dissipating heat, it is possible to prevent the temperature of the CPU 34 from rising excessively. Further, the cooling effect is further enhanced by receiving the wind from the cooling fan 26 at the end 39 of the heat pipe 38. However, the cooling fan 26 may be omitted depending on the thermal conditions. The heating element in which the heat transport device 11 transports heat is not limited to the CPU 34, and may be, for example, an SSD 24, an antenna 30, a memory 36, a battery charger, or the like.

Almost the entire surface of the inner surface 12Aa of the housing member 12A in contact with the heat transport device 11 is coated with a metal film (heat transfer material) 52. The metal film 52 includes a portion of the portion in contact with the heat transport device 11 that includes the boundary between the heat pipe 38 and the first plate member 44 in a plan view and the boundary between the first plate member 44 and the second plate member 46. When provided in the portion, the thermoconductivity between these two members can be enhanced. In particular, if there is a concern that the contact between these two members will be insufficient for some reason (for example, manufacturing error or aging), or if the housing member 12A is made of a material with low heat transfer properties (for example, resin material). When so, it is preferable to be able to complement the thermoconductivity between the two members. When the metal film 52 is provided in at least a part of the portion in contact with the heat transport device 11, the thermal conductivity can be enhanced.

The metal film 52 is a metal material having a higher heat transfer property than the housing member 12A, and is, for example, aluminum or copper. The metal film 52 is formed by vapor deposition on the inner surface 12Aa of the housing member 12A, adhesion of a metal foil, or application of a paint containing metal, and is sufficiently thin. In FIG. 4, the metal film 52 is shown as a dot.

FIG. 5 is a cross-sectional side view of the housing member 12A in the electronic device 10. As shown in FIG. 5, the heat pipe 38 has a heat receiving surface 38a that is in contact with the CPU 34 and receives heat, two side surfaces 38b that are orthogonal to the heat receiving surface 38a, and a facing surface 38c that is opposite to the heat receiving surface 38a. Have. The side surface 38b does not have to be orthogonal to the heat receiving surface 38a, and may be a surface that intersects at an angle to some extent, for example. The side surface 38b does not have to be a flat surface, and may be, for example, an uneven surface or a curved surface. The heat receiving surface 38a is the upper surface, and the facing surface 38c is the lower surface. The CPU 34 and the heat receiving surface 38a do not have to be in direct contact with each other as long as they are thermally connected. For example, a heat transfer plate or grease for enhancing heat transfer may be provided between the two.

The first plate member 44 is in contact with the side surface 38b of the heat pipe 38 by being press-fitted and fixed. The second plate member 46 is in contact with the first plate member 44 by being press-fitted and fixed to the side opposite to the heat pipe 38. In this way, the side surfaces of the first plate member 44 and the heat pipe 38 are thermally connected to each other, and the side surfaces of the first plate member 44 and the second plate member 46 are thermally connected to each other. Further, as described above, the heat pipe 38 and the first plate member 44 have the same thickness, and the second plate member 46 is thinner than the first plate member 44.

With such a configuration, the heat generated by the CPU 34 is transferred and diffused from the heat pipe 38 to the first plate member 44 and the second plate member 46 as shown by the arrow A.

The lower surface 44a (connection plane) of the first plate member 44 and the lower surface 46a (connection plane) of the second plate member 46 are formed on the same plane as the facing surface 38c of the heat pipe 38. The lower surface 44a of the first plate member 44 and the lower surface 46a of the second plate member 46 have the facing surfaces 38c of the heat pipe 38 facing each other with the inner surface 12Aa of the housing member 12A via the metal film 52, respectively. The metal film 52 and the inner surface 12Aa function as a heat transfer material that thermally connects the heat pipe 38, the first plate member 44, and the second plate member 46. Such a heat transfer material may be either the metal film 52 or the housing member 12A. When the housing member 12A is used as a heat transfer material, it may be made of metal. Such a heat transfer material is in contact with the lower surfaces 44a and 46a of the heat pipe 38, the first plate member 44 and the second plate member 46, which are coplanar, and promotes heat transfer between them. The form in which the heat transfer material and the heat pipe 38, the first plate member 44, and the second plate member 46 are in contact with each other may be a heat connection, and for example, another thin heat transfer material such as an adhesive or grease is interposed. You may.

With such a configuration, the heat generated by the CPU 34 is transferred from the heat pipe 38, the first plate member 44 and the second plate member 46 to the metal film 52 and the housing member 12A as shown by the arrow B, in addition to the path indicated by the arrow A above. Heat is transferred to and diffused.

Adhesive between the heat transport device 11 and the metal film 52, or between the heat transport device 11 and the housing member 12A, with an adhesive having thermal conductivity (for example, graphite base agent, silicon-based agent) in whole or in part. Has been done. In consideration of repairability, this adhesive has an appropriate adhesive strength such that the heat transport device 11 can be removed from the housing member 12A.

In the heat transport device 11 configured in this way, the heat pipe 38 is sandwiched between the CPU 34 and the housing member 12A, and since the heat spreader 40 does not overlap this portion, it can be formed thin in the vertical direction. ..

Further, the heat pipe 38 and the first plate member 44 have the same thickness, a wide contact area is secured, and the thermal conductivity is high. Since the first plate member 44 has an area equal to or larger than that of the heat pipe 38, it can receive heat from the heat pipe 38 and dissipate heat appropriately.

Further, since the second plate member 46 meshes with the first plate member 44 at the meshing portion 48, a large contact area is secured and the thermal conductivity is high. The second plate member 46 is wider than the first plate member 44 and has high heat dissipation performance. The second plate member 46 is wider than the first plate member 44, but is lighter because it is formed thinner.

Further, since the lower surfaces of the heat pipe 38, the first plate member 44, and the second plate member 46 form the same plane and are in contact with the housing member 12A via the metal film 52, these three are in contact with each other. The thermal conductivity between the members is increased, and it becomes easier to dissipate heat.

As shown in FIG. 5, the first plate member 44 is provided on both sides of the heat pipe 38, but only one of them may be used depending on the design conditions. Similarly, the second plate member 46 is provided on both sides of the heat pipe 38 with the first plate member 44 interposed therebetween, but only one of them may be used depending on the design conditions.

6A and 6B are views showing a modification of the heat transport device 11, FIG. 6A is a cross-sectional side view of the heat transfer device 11A according to the first modification, and FIG. 6B is a cross-sectional side view of the heat transfer device 11A. It is a cross-sectional side view of the device 11B, (c) is a cross-sectional side view of the heat transport device 11C according to the third modification, and (d) is a cross-sectional side view of the heat transfer device 11D according to the fourth modification. .. In each modification, the same components as those of the heat transport device 11 are designated by the same reference numerals, and detailed description thereof will be omitted.

As shown in FIG. 6A, the heat transport device 11A according to the first modification includes a heat pipe 38 and a heat spreader 40a. The heat spreader 40a includes a first plate member 45a and a second plate member 47a. The second plate member 47a is the same as the second plate member 46 described above. The side of the first plate member 45a in contact with the side surface 38b of the heat pipe 38 has an appropriate thickness like the heat pipe 38, and the side in contact with the second plate member 47a has an appropriate thickness like the second plate member 47a. It is thin and the top surface is an inclined surface that connects these two sides. Due to such a shape, the weight of the first plate member 45a can be reduced.

As shown in FIG. 6B, the heat transport device 11B according to the second modification includes a heat pipe 38 and a heat spreader 40b. The heat spreader 40b includes a first plate member 45b and a second plate member 47b. The first plate member 45b has the same thickness and area as the first plate member 44, and the second plate member 47b has the same thickness and area as the second plate member 46. The first plate member 45b and the second plate member 47b are integrated and have high thermal conductivity. The heat spreader 40b is formed by, for example, scraping the upper part of the second plate member 47b from a base material having the same thickness as the first plate member 45b by machining (for example, CNC (Computerized Numerical Control)), or is a separate member. It is obtained by integrating the 1st plate member 45b and the 2nd plate member 47b by welding. The upper surface of the first plate member 45b may be an inclined surface like the first plate member 45a in (a).

As shown in FIG. 6C, the heat transport device 11C according to the third modification includes a heat pipe 38 and a heat spreader 40c. The heat spreader 40c is press-fitted and fixed to the heat pipe 38 in the same manner as the first plate member 44 described above. The heat spreader 40c has the same thickness as the above-mentioned second plate member 46, and has an area including the first plate member 44 and the second plate member 46. That is, the heat spreader 40c has an indistinguishable shape like the first plate member 44 and the second plate member 46 described above, and is appropriately thin and lightweight. In such a heat transport device 11C, the area directly in contact between the heat pipe 38 and the heat spreader 40c is slightly small, but thermally via the metal film 52 and the housing member 12A (or one of them). Heat transfer performance is guaranteed because it is indirect contact.

As shown in FIG. 6D, the heat transport device 11D according to the fourth modification includes a heat pipe 38 and a heat spreader 40d. The heat spreader 40d is press-fitted and fixed to the heat pipe 38 in the same manner as the first plate member 44 described above. The heat spreader 40d has the same thickness as the first plate member 44 described above, and has an area including the first plate member 44 and the second plate member 46. That is, the heat spreader 40c has a shape that is not classified like the first plate member 44 and the second plate member 46 described above. In such a heat transport device 11D, the area of direct contact between the heat pipe 38 and the heat spreader 40d is appropriately large, and the heat pipe 38 and the heat spreader 40d are indirectly contacted via the metal film 52 and the housing member 12A. The heat transfer performance is further improved. The heat spreader 40d is lighter than copper when, for example, aluminum is used.

FIG. 7 is a plan view of the heat transport device 11E according to the fifth modification. As shown in FIG. 7, the heat transport device 11E according to the fifth modification includes two heat pipes 56 and a heat spreader 57. The heat spreader 57 includes a first plate member 58 and a second plate member 60. The heat pipe 56, the heat spreader 57, the first plate member 58, and the second plate member 60 correspond to the heat pipe 38, the heat spreader 40, the first plate member 44, and the second plate member 46.

The heat spreader 57 is a horizontally long rectangle and partially includes a protrusion 57a. One end of the two heat pipes 56 is arranged at the protrusion 57a and spreads in a flat Y shape, and the other ends extend to the vicinity of each corner of the heat spreader 57. The first plate member 58 has a shape that surrounds the entire protrusion 57a and the two heat pipes 56 that spread in a Y shape. The heat pipe 56 and the first plate member 58 have the same thickness and are press-fitted and fixed. The second plate member 60 forms a portion of the heat spreader 57 other than the first plate member 58. The first plate member 58 and the second plate member 60 are press-fitted and fixed while being meshed with each other at the meshing portion 48. The second plate member 60 is thinner and wider than the first plate member 58.

The main substrate 20a to be combined with the heat transport device 11E has a long shape and overlaps the protrusion 57a in a plan view. The CPU 34 of the main board 20a is located at the protrusion 57a in a plan view, and is in contact with the heat pipe 56 to transfer heat. In this way, if the CPU 34 to be cooled is in contact with the heat pipe 56, the other parts of the main board 20a do not have to overlap with the heat transport device 11E, and the degree of freedom in layout is increased.

Further, the adhesive 62 for fixing the heat transport device 11E and the inner surface 12Aa of the housing member 12A is located at a location separated from the CPU 34 in the heat spreader 57 (for example, near the end opposite to the connection end with the CPU 34 in the heat pipe 56). ) May be provided. As a result, the heat generated by the CPU 34 is not directly transferred to the housing member 12A, and it is possible to suppress the generation of hot spots on the housing member 12A, which gives the user a sense of discomfort. There is no.

Similarly, if the metal film 52 provided on the inner surface 12Aa is provided at a position slightly separated from the CPU 34 (for example, an area along the side opposite to the side where the protrusion 57a is provided and including most of the meshing portions 48), It is possible to prevent the occurrence of hot spots in the housing member 12A. Further, if the cover 18 (see FIG. 5) is made of a heat insulating material such as polyurethane, the discomfort given to the user by the hot spot can be further reduced.

The present invention is not limited to the above-described embodiment, and it goes without saying that the present invention can be freely modified without departing from the gist of the present invention.

10 Electronic equipment 11,11A, 11B, 11C, 11D, 11E Heat transport device 12A, 12B Housing member 12Aa, 12Ba Inner surface 16 Display 18 Cover 20,20a Main board 26 Cooling fan 34 CPU (heating element) 38,56 Heat pipe 38a Heat receiving surface 38b Side 38c Facing surface 40,40a, 40b, 57 Heat spreader 44,45a, 45b, 58 1st plate member 46,47a, 47b, 60 2nd plate member 48 Engagement part 52 Metal film 57a Protrusion part 62 Adhesive