JP3412604B2 - Electronic equipment - Google Patents

Description

Description: BACKGROUND OF THE INVENTION [0001] 1. Field of the Invention [0002] The present invention relates to a cooling structure for a small electronic device, and more particularly to a cooling device for cooling a heating element to maintain a predetermined temperature. 2. Description of the Related Art Conventional electronic equipment is disclosed in Japanese Patent Application Laid-Open No. 4-4879.
No. 7, JP-A-55-125699, and an example in which a metal plate is formed into a leaf spring shape or an elastic resin is interposed between a heat generating member and a heat radiating member to cool the metal plate. It is shown. Also, JP-A-63-25090
0, Japanese Unexamined Patent Publication No. Hei 3-255697,
As described in Japanese Patent No. 29153, an independent metal plate or a metal plate constituting a part of a housing is interposed between a heat generating member and a metal housing wall, and heat generated by the heat generating member is radiated by a heat radiating portion. It is transported by heat conduction to the metal housing wall, which dissipates heat. [0003] The above conventional example is disclosed in Japanese Unexamined Patent Publication No.
In the examples described in JP-A-3-250900, JP-A-3-255697, and JP-A-5-29153, depending on the component arrangement, the distance to the metal housing wall is not always short. . For this reason, the arrangement of parts or the structure of the housing is limited, such as disposing the heating member near the housing. On the other hand, in electronic devices and the like that require high performance, the heating elements mounted on the wiring board are uniquely determined on the wiring board due to the speeding up of electronic circuits and the layout of other components. Would. Also, regarding the heat dissipating member, there is a restriction on the installation place of the heat dissipating member in order to obtain high heat dissipating performance. In the above-mentioned conventional example, the heat generating element and the heat radiating member can be realized only in a positional relationship on the same side and close to the wiring board. Therefore, the realization of an optimal arrangement configuration is greatly restricted, which hinders downsizing and high performance of electronic devices. SUMMARY OF THE INVENTION It is an object of the present invention to cool a heating element to a predetermined temperature at a position on a wiring board of the heating element and a position at which a heat radiating member is installed without obstructing the arrangement. I do. [0005] An object of the present invention is to provide an electronic device including a substrate mounted in a case, a heating element mounted on the substrate, and a keyboard mounted on the case. in, on the back side of the keyboard, and the first heat radiating plate to continue the heating elements in thermal contact, with the bottom side of the case, and a second heat radiating plate to continue the heating elements in thermal contact wherein the first heat radiating plate and the second heat radiating plate thermally <br/> connected to the heat conducting member is achieved by provided through the substrate. An embodiment of the present invention will be described with reference to FIG. Personal computer according to the present embodiment
An electronic device such as a heater includes a first wiring board 1 on which a plurality of heating elements including a heating element is mounted, and a second wiring board 3 on which a main heating element 2 is mounted. A palm rest 8 and a keyboard 9 are mounted on a housing 7 in which a housing 6 and the like are accommodated, and a folding display 10 is further provided. The main heating element 2 is, for example, a C
PU (hereinafter, referred to as CPU2). The second wiring board 3 can be detached from the wiring board 1, and can be easily replaced or upgraded.
Inside the housing 7, a heat radiating plate 11 having almost the same size as the bottom surface of the housing is laid. The CPU 2 mounted on the second wiring board 3 has an enlarged metal plate 13 attached together with a frame 14 via a flexible heat conductive member 12 described in detail later. Second wiring board 3 is electrically connected to wiring board 1 via connector 15. Then, the second wiring board 3
Is thermally connected via a flexible heat conductive member 12 between a heat radiating block 16 adhered to or integrally formed with the heat radiating plate 11 and the enlarged heat radiating plate 13. Note that the heat radiation block 16 is provided through a hole provided in the wiring board 1 as illustrated. The details of cooling the CPU 2 shown in FIG. 1 will be described with reference to FIG. For example, the CPU 2
In the package of the tape-shaped carrier, the back surface of the element is bonded to the second wiring board 3, and the surface is pressed against the flexible heat conductive member 12. Further, this flexible heat conductive agent 12 is
2 and an expanded metal plate 13 suspended by an electrically insulating frame 14 fixed to the second wiring board 3, and the flexible heat conductive member 12 and the expanded metal plate 13 are pressed against each other. ing. The enlarged metal plate 13 includes a CPU serving as a heating element.
2 diffuses the generated heat and also provides mechanical protection to the device. The thermal conductivity of the enlarged metal plate 13 is larger than that of the flexible thermal conductive member 12. The radiator plate 11 is made of Al, M
It is a metal plate of high thermal conductivity such as g or Cu, and is laid on the bottom of the housing 7 with almost the same area as the bottom surface of the housing. By laying it on the bottom of the housing, a large heat dissipation area can be secured without any spatial restrictions on the mounted components and the like, and heat can be efficiently radiated to the outside air by contacting the housing 7. In addition, on the bottom surface of the housing, the heat radiation block 16
Can be installed, so that the CPU 2 on the wiring board 3
There is no restriction on the mounting position of. In order to enhance the heat diffusion effect of the heat radiating plate 11, a heat pipe or the like may be laid and connected, or the heat radiating plate and the heat pipe may be integrally formed. [0009] The second wiring board 3, the connector 15a on the wiring substrate 1, Ru are electrically connected via 15b. In the enlarged metal plate 13 , a heat radiating block 16 provided through the wiring board 1 is thermally connected to the heat radiating plate 11 via a flexible heat conductive member 17. The flexible heat conductive member 17 absorbs manufacturing crossovers such as variations in connector mounting height and variations in the inclination of the enlarged metal plate, secures a contact area, connects with a small thermal resistance, and is resistant to shock applied from outside the housing 7. It also acts as a cushioning material. In addition, since the surfaces of the flexible heat conductive members 12 and 17 have an adhesive property and are pressed against the heat sink 11 and the second wiring board 3, they are not bonded by using an adhesive or the like. At the same time, the pressing force is generated by the reaction force of the pressure contact, so that the personal computer is not shaken when it is carried. On the other hand, the heat path from the back of the wiring board is CP
Depending on the amount of heat generated by U2, a narrow gap in the air layer may be used (heat conduction of air), and if the amount of generated heat is small, a heat path may not be provided. In addition, the flexible heat conductive member 12,
17 (the same applies to the flexible heat conductive member 20 described later) is, for example, a material obtained by mixing a filler such as aluminum oxide into Si rubber or a gel-like high heat conductive Si resin. According to the present embodiment, the main heat-generating element and the heat-dissipating plate are isolated from each other by the wiring board or the like, because the heat-dissipating plate is provided at a position where high heat-dissipating performance can be ensured in the structure of the electronic circuit. Even in the case of the positional relationship, the heat generated by the heat generating element can be diffused, and the heat can be conducted to the heat radiating plate by the heat radiating block penetrating the wiring board, so that heat can be efficiently radiated to the outside of the housing. According to an embodiment of the present invention, in the case where a wiring board is installed between the heating element and the heat sink (the positional relationship between the heating element and the heat dissipation member is different from the wiring board) Side), a radiator plate of almost the same size as the bottom of the case is laid on the bottom of the case, and a radiator block is provided at an arbitrary position of the radiator plate through the wiring board. The heat radiating plate is thermally connected at the shortest distance, and can be cooled efficiently with small thermal resistance. Further, depending on the surface on which the heating element is mounted or the structure of the package, heat can be diffused by the enlarged heat sink on the back side of the board on which the heating element is mounted, and then heat can be conducted to the heat sink through the wiring board. Therefore, there is an effect that cooling can be performed efficiently. FIG. 3 shows another embodiment. The difference from the embodiment shown in FIG. 2 is that a heat conducting member is also provided between the back surface of the second wiring board 3 and the keyboard 9.
A metal plate 19 is attached to the back surface of the second wiring board 3 via an insulating sheet 18, and is connected to the back surface of the keyboard 9 via a flexible heat conductive member 20. As a result, a heat conduction path from the back of the heating element to the keyboard through the wiring board is formed. The back of the keyboard to which the flexible heat conducting member 20 is connected is a metal plate forming the lower surface of the keyboard or a metal plate further provided below the keyboard. As a result, in addition to the heat radiated from the heat radiating plate at the bottom of the housing, the heat conducted to the keyboard side is diffused in the keyboard surface direction and can be radiated from the keyboard surface to the outside air. A cooling effect is obtained. This is more effective when the amount of heat generated by the CPU 2 is large. FIG. 4 shows another embodiment. The second embodiment is different from the second embodiment in that the second wiring board 3 on which the CPU 2 is mounted is electrically connected to the wiring board 1 by a connector 15 as shown in FIG.
However, the point that the surface of the CPU 2 is directly connected via a flexible heat conductive member 12 to a heat radiating block 16 provided on a heat radiating plate 11 laid on the bottom of the housing 7 is similar to the embodiment shown in FIG. different. The size of the cross section of the heat radiating block 16 is larger than the contact area with the flexible heat conducting member 12, and the heat of the heat generating element 2 is diffused in the cross sectional direction and the heat radiating plate 11 is formed.
Conducts heat. In the present embodiment, the number of flexible heat conducting members used is smaller than in the embodiment of FIG. 2, so that the heat generating element and the heat sink at the bottom of the housing can be connected with a small thermal resistance. FIG. 5 shows another embodiment. This embodiment has an electronic circuit configuration similar to that of FIGS.
2 is mounted on the second wiring board 3 on a different surface from the heat sink 11 laid on the bottom of the housing 7. The rear surface of the second wiring board 3 is provided with an enlarged metal plate 19 via an insulating sheet 18.
Is attached, and connected to the heat radiation block 16 provided on the heat radiation plate 11 laid on the bottom of the housing 7 via the flexible heat conductive member 20. In the present embodiment, the heat generated by the CPU 2 is conducted in the second wiring board 3, and the heat is first diffused in the plane direction by the enlarged metal plate 19. Then, after the heat is transmitted to the heat radiation block 16 through the flexible heat conductive member 20, the heat is diffused sufficiently by the heat radiation plate 11 and is radiated to the outside air. Since the thermal conductivity of the flexible heat conductive member 20 is smaller than that of metal, the heat is first diffused by the enlarged metal plate 19 to increase the contact area with the flexible thermal conductive member and reduce the thermal resistance. Note that the wiring board 3 has a plurality of copper wiring layers formed therein, so that the thermal conductivity is generally larger than that of the flexible heat conductive member. Therefore, even if heat is conducted through the wiring board, the thermal resistance occupying the whole is small. Further, since the thermal conductivity in the plane direction is increased by the copper wiring layer, an in-plane heat diffusion effect can be expected. FIG. 6 shows another embodiment. The present embodiment has a structure similar to that of FIG. 2 except that enlarged metal plates 13 and 1 provided on the front surface of CPU 2 and the back surface of second wiring board 3 are provided.
The difference is that heat is conducted from 9 to the heat radiating plate 11 laid on the bottom of the housing 7 via the heat radiating block 16. The surface of CPU2 is
It is thermally connected to the first enlarged metal plate 13 via the flexible heat conductive member 12, while the back surface of the wiring board 3 is
8 and is thermally connected to the second enlarged metal plate 19. The first enlarged metal plate 13 and the second enlarged metal plate 19 are screwed through the second wiring board 3 with metal rods or screws 21 having high thermal conductivity such as aluminum or copper. The first enlarged metal plate 13 and the heat radiation block 16 are connected via a flexible heat conductive member 17. The heat path on the back surface of the wiring board 3 is conducted to the first enlarged metal plate 13 by the metal rods 21 after the heat is diffused by the second enlarged metal plate 19. Therefore, in the first enlarged metal plate 13, the heating element 2
The heat generated by the heat conduction is conducted from both surfaces to the heat radiating block 16 via the flexible heat conductive member 17, and high heat radiating performance can be obtained. Note that the structure on the back surface of the wiring board 3 can be realized with a small thermal resistance as described in FIG. FIG. 7 shows a case where heat conduction paths are formed on both surfaces of the heating element 2 as in FIG. 6, but no metal rod is provided, and the first enlarged metal plate 13 is attached to the wiring board 3 by the frame 14. . The material of the frame 14 is desirably a metal, and the frame 14 is attached to the wiring board with an electrically insulating double-sided tape or the like. In this embodiment, the first enlarged metal plate 13 and the second
The thermal resistance between the second enlarged metal plate 19 and the second enlarged metal plate 19 is increased by using the frame 14 to increase the cross-sectional area of the heat conduction path and the contact area with the wiring substrate. 3 can also be connected with a small thermal resistance. As in the embodiment shown in FIG.
Also in the present embodiment, in the first enlarged metal plate 13,
The heat generated by the heat generating element 2 is conducted from both surfaces thereof to the heat radiating block 16 via the flexible heat conductive member 17, and high heat radiating performance is obtained. In FIGS. 6 and 7,
The CPU 2 can have the same configuration regardless of which surface is mounted on the wiring board 3, and is not restricted by the mounting arrangement by the electronic circuit. The embodiment shown in FIGS. 8 and 9 has the same wiring board configuration as the above-described embodiment, but is an embodiment in which a relatively large through hole of the heat radiation block is not provided on the wiring board. It is. The embodiment shown in FIG.
9 is mounted on a surface of the second wiring board 3 that is not opposed to the wiring board 1, and the embodiment shown in FIG. In FIG. 8, the enlarged metal plate 13 is connected to the heating element 2 via the flexible heat conductive member 12.
A plurality of metal rods 22 (a high thermal conductivity material such as aluminum and copper) are provided on the surface and at the end of the enlarged metal plate 13.
Is fixed with screws. The metal rod 22 is provided on the heat radiating plate 11 laid on the bottom surface of the housing 7 through the wiring board 1. On the other hand, in the embodiment of FIG. 9, the second enlarged metal plate 19 is provided on the back surface of the second wiring board 3 via the insulating sheet 18, and the enlarged metal plate 13 is connected via the flexible heat conductive member 20. . Other parts are the same as those of the embodiment of FIG. A structure in which a relatively large through-hole is provided in a wiring board as shown in the embodiments of FIGS. 1 to 7 may be difficult in designing a wiring pattern of the board. 8 and 9
In the embodiment, the diameter of the through hole provided in the wiring board is reduced by dispersing a plurality of heat conduction paths from the enlarged metal plate 13 to the radiator plate 11 laid on the bottom surface of the housing, and the thermal resistance to the radiator plate is increased. The wiring pattern design can be facilitated without performing. Although the above-described embodiment has shown the case where the second wiring board on which the CPU 2 is mounted is formed separately and independently, it is also applicable to the case where the CPU is mounted on a single wiring board. In particular, the embodiments shown in FIGS. 8 and 9 can be applied to a case where a CPU is mounted on a single wiring board with the same structure. Further, as an example, FIG. 10 shows an example in which the structure of the embodiment of FIG. 6 is applied to a case where a CPU is mounted on a single wiring board. From the enlarged metal plates 13 and 19 provided on the front surface of the CPU 2 and the back surface of the wiring board 1,
Conducts heat to the heat sink 11 laid on the bottom. The surface of the CPU 2 is provided on the first enlarged metal plate 13 via the flexible heat conductive element 12.
On the other hand, a second enlarged metal plate 19 is provided on the rear surface of the wiring board 1 via an insulating sheet 18. The first enlarged metal plate 13 and the second enlarged metal plate 19 are connected to the wiring board 1 by metal rods or screws 21 having high thermal conductivity such as aluminum or copper.
Is screwed through. The first enlarged metal plate 13 and the heat radiating plate 11 laid on the bottom of the housing 7 are
Connected via The heat path on the back surface of the wiring board 1 is formed by a metal rod 2 after heat is diffused by the second enlarged metal plate 19.
At 1, heat is conducted to the first enlarged metal plate 13. Therefore, in the first enlarged metal plate 13, heat generated in the heating element 2 is thermally conducted from both surfaces thereof to the heat radiating plate 11 laid on the bottom of the housing 7 via the flexible heat conducting member 17. Heat dissipation performance is obtained. FIG. 11 shows another embodiment. The present embodiment has a structure similar to that of FIG. 9, except that the second wiring board 3 is relatively installed at the end of the wiring board 1. In the present embodiment, a second enlarged metal plate 19 is provided on the back surface of the second wiring board 3 via an insulating sheet 18, and the first enlarged metal plate 13 is connected via a flexible heat conductive member 20. The enlarged metal plate 13 is fixed to the heat dissipation block 16 at the end of the enlarged metal plate 13 by screws or the like.
The heat radiation block 16 is provided on the heat radiation plate 11 laid on the bottom surface of the housing 7 on the side of the wiring board 1. FIG. 11 particularly shows a structure in the case where the positional relationship of the CPU 2 is similar to that of FIG. 9, but can be applied to the examples shown in FIGS. According to the present embodiment, there is no need to provide a through hole in the wiring board, and the wiring pattern of the wiring board 1
The CPU 2 can be cooled without any restrictions. The above embodiment is an example in which the present invention is mainly applied to a portable electronic device such as a personal computer or a word processor.
Alternatively, it is preferable that the surface temperature of the housing when the housing is moved after the power is turned off is a temperature that does not cause discomfort. Empirically, in consideration of the human body temperature, the temperature difference between the outside air temperature and the temperature of the touching portion may be about 10 ° C. or less. In the embodiments of FIGS. 1 to 11 described above, a radiator plate is laid on the bottom of the case, and the heat sink is connected from the CPU to the radiator plate with a small thermal resistance. The rate of heat dissipation is increased. Thereby, the temperature rise on the keyboard surface can be suppressed. On the other hand, let us focus on the case surface temperature. FIG. 12 shows the relationship between the elapsed time when a finger is touched on the housing surface, the housing surface temperature, and the sensed temperature of the finger after the power is turned off when the housing surface temperature is 55 ° C. (when the outside air temperature is 35 ° C.). Relationship. As shown in FIG. 12, if the housing surface temperature is 55 ° C. (temperature difference from outside air temperature 20 ° C.), the sensible temperature of the finger does not exceed 45 ° C. (temperature difference from outside air temperature 10 ° C.). . Therefore, the ratio of the amount of heat radiation from the bottom surface of the housing is controlled so that the amount of heat radiation from the keyboard surface is suppressed, and the temperature difference from the outside air temperature is 10 ° C or less on the keyboard surface and 20 ° C or less on the bottom surface of the housing. To keep. Thereby, cooling can be performed without giving an uncomfortable feeling to the operator. The control of the ratio of the heat release amount can be controlled mainly by the cross-sectional area of the heat-dissipating block, the cross-sectional area and thickness of the flexible heat-conducting member, and the thickness and size of the enlarged heat-dissipating plate shown in FIGS. According to the present invention, even if the positional relationship between the heating element and the heat radiating member is on the different side with respect to the wiring board,
The heating element can be cooled to a predetermined temperature without disturbing an optimal arrangement configuration with respect to the position of the heating element on the wiring board and the position where the heat radiation member is installed.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective sectional view of an embodiment of the present invention. FIG. 2 is a detailed sectional view of the embodiment shown in FIG. 1. FIG. FIG. 4 is a cross-sectional view of another embodiment of the present invention. FIG. 5 is a cross-sectional view of another embodiment of the present invention. FIG. 6 is a cross-sectional view of another embodiment of the present invention. FIG. 8 is a sectional view of another embodiment of the present invention. FIG. 9 is a sectional view of another embodiment of the present invention. FIG. 10 is a sectional view of another embodiment of the present invention. FIG. 11 is a cross-sectional view of another embodiment of the present invention. FIG. 12 is a diagram illustrating the effect of the present invention. Second wiring board, 7 ...
Case, 11: heat dissipation plate, 12: flexible heat conduction member, 17: flexible heat conduction member, 20: flexible heat conduction member, 13: enlarged metal plate, 19: enlarged metal plate, 16: heat dissipation block, 21: metal rod , 22 ... metal rod.

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Takeshi Nakagawa 810 Shimo-Imaizumi, Ebina-shi, Kanagawa Prefecture Hitachi, Ltd. Office Systems Division (72) Inventor Susumu Iwai 810 Shimo-Imaizumi, Ebina-shi, Kanagawa Hitachi, Ltd. Office Systems Division (72) Inventor Hitoshi Matsushima 502 Kandachicho, Tsuchiura City, Ibaraki Pref. Machinery Research Laboratory, Hitachi, Ltd. (56) References JP-A-4-354010 (JP, A) JP-A-5-298961 ( JP, A) JP-A-6-85120 (JP, A) JP-A-61-205196 (JP, U) JP-A-63-80894 (JP, U) JP-A-63-128776 (JP, U) (58) ) Surveyed field (Int.Cl. ⁷ , DB name) H05K 7/20

Claims (1)

(57) [Claim 1] An electronic device comprising a substrate mounted in a case, a heating element mounted on the substrate, and a keyboard mounted on the case. at the rear side of the keyboard, and the first heat radiating plate to continue the heating elements in thermal contact, with the bottom side of the case, the heating elements in thermal contact
And a second heat radiating plate continued to, an electronic device in which the first heat radiating plate and the second heat radiating plate thermally conductive member for connecting thermally a is provided through the substrate.