JP2007274001A - Printed circuit board with cooling device and electronic apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a printed circuit board with a cooling device which greatly help thin down an electronic apparatus. <P>SOLUTION: A fan case 39 of a fan unit is constituted of the printed circuit board 19, a wall 45 for the fan case which stands up from a surface of the printed circuit board 19 around a fan 44, and a ceiling wall 41 which spreads along a reference plane parallel to the surface of the printed circuit board 19. Rapid air flow in the fan case 39 facilitates heat radiation of the printed circuit board 19. Generally, since a metal conductive pattern is extended on the surface of the printed circuit board 19, heat radiation from the board 19 can be positively facilitated. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a printed circuit board unit with a cooling device incorporated in an electronic device such as a personal digital assistant (PDA) or a notebook personal computer, and in particular, a fan that rotates about a rotation center intersecting the printed circuit board and the surface of the printed circuit board. And a printed circuit board unit including a fan case that houses the fan.

  For example, as disclosed in Japanese Patent Application Laid-Open No. 2000-77877, a so-called fan unit includes a fan case that houses a fan that rotates about a rotation axis. When the fan rotates, air is blown away from the rotation center in the centrifugal direction. The blown air is guided to the fan case and guided to the exhaust port. Thus, while air is discharged from the exhaust port, ambient air is taken into the fan case from the intake port. These air inlets face the surface of the printed circuit board. When air is sucked into the fan case, an air flow is generated along the surface of the printed circuit board.

  In general, a large number of electronic components are mounted on the surface of a printed circuit board. Protrusion of electronic components obstructs smooth air flow. Such turbulence disturbs the intake of the fan. The intake air amount decreases. The cooling efficiency of the fan decreases. As the printed circuit board unit becomes thinner, the distance between the fan case and the surface of the printed circuit board is reduced. The cooling efficiency of the fan is further reduced.

  The present invention has been made in view of the above circumstances, and an object thereof is to provide a printed circuit board unit with a cooling device that can greatly contribute to a reduction in thickness of an electronic device.

  To achieve the above object, according to the first aspect of the present invention, a printed circuit board, a fan that rotates about a rotation center that intersects the surface of the printed circuit board, and a wall for a fan case that rises from the surface of the printed circuit board around the fan. And a printed circuit board unit with a cooling device provided with an exhaust port defined by a wall for a fan case.

  The printed circuit board and the fan case wall can cooperate to define a space for accommodating the fan. When the fan rotates, air movement, that is, airflow is caused in the space. The printed circuit board and the fan case wall induce airflow to the exhaust port. Thus, the printed circuit board serves as a part of the cooling device.

  In particular, in such a printed circuit board unit, a high-speed air current can be generated in the space. Such an air flow can efficiently remove heat from the printed circuit board. Heat dissipation of the printed circuit board is promoted. Generally, a metal conductive wiring pattern is stretched around the surface of a printed board. Such conductive wiring patterns often have excellent thermal conductivity characteristics compared to the material of the printed circuit board. The conductive wiring pattern can greatly contribute to heat dissipation of the printed circuit board. In particular, if the conductive wiring pattern spreads inside the fan case wall, heat dissipation of the printed circuit board can be greatly promoted.

  The printed circuit board unit with a cooling device further includes a ceiling wall connected to the upper end of the wall for the fan case and extending along a reference plane parallel to the surface of the printed circuit board, and an air inlet formed in the ceiling wall. May be.

  In general, a large number of electronic components are mounted on the surface of a printed circuit board. Electronic components protrude from the surface of the printed circuit board. These protrusions of electronic components are thought to hinder smooth air flow. If the intake port opens at a predetermined height from the surface of the printed circuit board, a relatively good air flow can be formed despite the protrusion of the electronic component. Air can flow smoothly into the air intake. As a result of injecting a large amount of air, the cooling efficiency of the cooling device can be increased.

  For example, when such a printed circuit board unit with a cooling device is incorporated into an electronic device, the air inlet can face the inner surface of the housing of the electronic device. When air is sucked from the air inlet to the inside of the fan case wall, an air flow is generated along the inner surface of the housing. In general, the inner surface of the housing is formed on a smooth flat surface as compared with the surface of the printed circuit board. There are few obstacles that obstruct air flow. A smooth airflow is generated along the inner surface of the housing. Since air smoothly flows into the intake port in this way, sufficient cooling efficiency can be ensured even if the interval between the intake port and the inner surface of the housing is reduced. Thinning of electronic devices can be realized with certainty.

  Such a printed circuit board unit with a cooling device may further include an air inlet that is formed in the printed circuit board inside the fan case wall. According to such an air inlet, air can flow toward the fan not only from the front side of the printed circuit board but also from the back side. A large amount of air can be taken into the space defined by the printed circuit board and the fan case wall. As a result of securing a large amount of intake air in this way, the cooling efficiency of the cooling device can be further enhanced. Moreover, the front side and the back side of the printed circuit board can be cooled simultaneously. However, in the printed circuit board unit with a cooling device, instead of the air intake port defined in the ceiling wall, only the air intake port on the printed circuit board side may be secured. Such a configuration can contribute to further thinning of the electronic device.

  In addition, the printed circuit board unit with a cooling device includes an electronic component mounted on the printed circuit board, a conductive wiring pattern extending along the surface of the printed circuit board inside the fan case wall, and connected to the electronic component. May be further provided. In such a printed circuit board unit with a cooling device, heat can be efficiently dissipated from the conductive wiring pattern by the function of the above-described fan. Heat dissipation of the printed circuit board is promoted. Moreover, since heat is efficiently transferred from the electronic component to the conductive wiring pattern, the electronic component can be efficiently cooled.

  A radiating fin attached to the printed circuit board may be connected to the conductive wiring pattern. The heat radiation fin can further promote the heat radiation from the conductive wiring pattern. Such heat radiating fins may be disposed in the above-described exhaust port, or may be opposed to the above-described exhaust port.

  An electronic component may be mounted on the surface of the printed board inside the fan case wall. As described above, a high-speed air current can be generated inside the fan case wall by the action of the blades. Therefore, the electronic component can be efficiently cooled. Such electronic components may be disposed in the above-described exhaust port, for example.

  As described above, according to the present invention, the printed circuit board unit with a cooling device can greatly contribute to the reduction in thickness of the electronic device.

  Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings.

  FIG. 1 shows an example of an electronic device, that is, an external appearance of a notebook personal computer (notebook personal computer) 11. The notebook computer 11 includes a thin device main body 12 and a display housing 13 that is swingably connected to the device main body 12. Input devices such as a keyboard 14 and a pointing device 15 are incorporated on the surface of the device main body 12. The user can operate the operation of the notebook personal computer 11 using the keyboard 14 and the pointing device 15.

  For example, an LCD (liquid crystal display) panel module 16 is incorporated in the display housing 13. The display screen of the LCD panel module 16 faces the window hole 17 defined in the display housing 13. The user can confirm the operation of the notebook personal computer 11 based on text and graphics appearing on the display screen of the LCD panel module 16, for example. The display housing 13 can be overlaid on the device main body 12 through swinging with respect to the device main body 12.

  As shown in FIG. 2, a printed circuit board unit 18 is incorporated in the device main body 12. The printed circuit board unit 18 includes a printed circuit board 19 and a central processing unit (CPU) package 21 mounted on the front surface of the printed circuit board 19. The CPU package 21 may include, for example, a small ceramic substrate 22 and a CPU chip 23 mounted on the substrate 22. In addition to the CPU package 21, various electronic components 24 a and 24 b are mounted on the front surface of the printed circuit board 19. .. Between the CPU package 21 and the other electronic components 24a, 24b... And between the electronic components 24a, 24b... By the action of a conductive wiring pattern (not shown) stretched on the front surface of the printed circuit board 19. Connection is established.

  For example, a storage battery 25 and a hard disk drive (HDD) 26 that are detachably incorporated in the device main body 12 are connected to the printed circuit board unit 18. The storage battery 25 can supply electric power to the printed circuit board unit 18 in place of, for example, an AC power source, that is, a commercial power source. The hard disk drive 26 stores an application program processed by the CPU chip 23 and various data used for executing the application program.

  The cooling device 27 according to the first embodiment of the present invention is connected to the CPU package 21. The cooling device 27 includes a heat transfer plate 28 superimposed on the upper surface of the CPU chip 23. One end of a heat conducting member such as a heat pipe 29 is connected to the heat transfer plate 28. The other end of the heat pipe 29 is connected to a heat radiating fin 31 attached to the printed circuit board 19. The heat of the CPU chip 23 is transmitted to the heat radiating fins 31 through the heat transfer plate 28 and the heat pipe 29. The heat radiation fins 31 protrude from the notch 32 formed in the printed circuit board 19 to the back side of the printed circuit board 19.

  As shown in FIG. 3, electronic components such as a memory module 35 such as a RAM, a PC card slot 36, and a LAN (local area network) module 37 are mounted on the back side surface of the printed circuit board 19. In this way, electronic components that are relatively tall compared to the front side of the printed circuit board 19 are mounted on the back side of the printed circuit board 19.

  As shown in FIG. 3, the cooling device 27 further incorporates a fan unit 38 attached to the back side surface of the printed circuit board 19. The fan unit 38 includes a fan case 39 fixed to the back surface of the printed circuit board 19. The fan case 39 is partitioned with a ceiling wall 41 extending along a reference plane parallel to the back surface of the printed circuit board 19. The ceiling wall 41 is partitioned with an air inlet 42 that interconnects the space inside the fan case 39 and the space outside the fan case 39.

  As is clear from FIG. 4, the fan case 39 accommodates a rotating body 43 that rotates around a rotation center CR that is orthogonal to the back surface of the printed circuit board 19. Around the rotator 43, a plurality of blades 44 radiating from the rotator 43 are integrally formed. For example, the blades 44 may be arranged around the rotating body 43 at equal intervals. Each blade 44 extends along a plane that intersects the vertical plane VP including the rotation center CR at a predetermined inclination angle α. When the rotating body 43 rotates, the blades 44 can send air in the centrifugal direction from the rotation center CR. Thus, the rotating body 43 and the blades 44 constitute a so-called fan.

  As is apparent from FIG. 4, a fan case wall 45 that rises from the back surface of the printed circuit board 19 around the blades 44 is defined in the fan case 39. The inner surface of the fan case wall 45 faces the outer end of the blade 44. The exhaust port 46 is defined by the cut of the fan case wall 45. The exhaust port 46 faces the heat radiating fin 31 described above. Inside the fan case wall 45, an air inlet 47 is formed in the printed circuit board 19. The air inlet 47 connects the space inside the fan case 39 and the space outside the fan case 39 to each other, like the air inlet 42 described above. The printed circuit board 19 constitutes a part of the fan case 39.

  As is clear from FIG. 5, the rotating body 43 of the fan unit 38 is attached to a rotating shaft 51 that extends along a vertical direction orthogonal to the back side surface of the printed circuit board 19. The rotating shaft 51 is supported by a bearing 52 that is fixed to the ceiling wall 41 of the fan case 39. A thin electric motor 53 is incorporated between the rotating body 43 and the bearing 52. The electric motor 53 may be configured by, for example, a permanent magnet 54 attached to the rotating body 43 and a coil 55 attached to the bearing 52 side and facing the permanent magnet 54. Such an operation of the electric motor 53 can be controlled by the action of a control circuit mounted on the control board 56.

  Now, when electric power is supplied to the electric motor 53, the rotating body 43 rotates around the rotation center CR. The blades 44 send air in the centrifugal direction from the rotation center CR. The air sent out is guided to the exhaust port 46 by the function of the fan case wall 45. In this way, air is discharged from the exhaust port 46.

  An opening 58 that faces the exhaust port 46 of the fan unit 38 is formed in the housing 57 of the device main body 12. The air discharged from the exhaust port 46 takes heat from the heat radiating fins 31 and then escapes from the opening 58 to the outside of the device body 12. Thus, the heat radiation of the heat radiation fins 31 is efficiently promoted.

  In the internal space surrounded by the printed circuit board 19, the fan case wall body 45 and the ceiling wall 41, a high-speed air flow is generated based on the rotation of the blades 44. Such airflow can efficiently remove heat from the surface of the printed circuit board 19. Heat dissipation of the printed circuit board 19 is promoted. In general, a conductive wiring pattern made of metal is stretched around the surface of the printed circuit board 19. Such a conductive wiring pattern can contribute to heat dissipation of the printed circuit board 19 because it has excellent heat conduction characteristics compared to the material of the printed circuit board 19. In particular, if the conductive wiring pattern spreads inside the fan case wall 45, the heat dissipation of the printed circuit board 19 can be greatly promoted.

  In this way, air is discharged from the exhaust port 46, while ambient air is taken into the fan case 39 from the intake port 42. Here, since the air inlet 42 formed in the ceiling wall 41 is opposed to the inner surface of the housing 57 of the device main body 12, when air is sucked into the fan case 39 from the air inlet 42, the housing of the device main body 12. An airflow 61 is generated along the inner surface of the body 57. In general, a large number of electronic components are mounted on the back side surface of the printed circuit board 19. The electronic component protrudes from the back side surface of the printed circuit board 19. These protrusions of electronic components are thought to hinder smooth air flow. On the other hand, the inner surface of the housing 57 of the device main body 12 is formed on a smooth flat surface as compared with the surface of the printed circuit board 19. There are few obstacles that obstruct air flow. A smooth airflow 61 is generated along the inner surface of the casing 57 of the device main body 12. Air can flow smoothly into the air inlet 42. As a result of injecting a large amount of air, the cooling efficiency of the fan unit 38 can be increased. Since air smoothly flows into the air inlet 42 in this way, sufficient cooling efficiency can be ensured even if the space between the ceiling wall 41 of the fan case 39 and the inner surface of the housing 57 is narrowed.

  At the same time, in the fan unit 38, air can be taken in from the air inlet 47 formed in the printed circuit board 19. Thus, air can flow into the fan unit 38 not only from the back side of the printed circuit board 19 but also from the front side. As a result of securing a large amount of intake air, the cooling efficiency of the fan unit 38 can be further enhanced. Moreover, although the fan unit 38 is disposed on the back side of the printed board 19, the front side of the printed board 19 can be cooled with relatively high efficiency.

  When the air inlet 47 is secured in the printed circuit board 19 in this way, the ceiling wall 41 of the fan case 39 may be completely overlapped with the inner surface of the housing 57 as shown in FIG. Thus, even if the air inlet 42 is closed, a sufficient supply of air from the air inlet 47 can be secured in the fan case 39. Therefore, sufficient cooling efficiency can be maintained in the fan unit 38. According to such a configuration, the device body 12 can be further reduced in thickness.

  FIG. 7 shows a cooling device 62 according to the second embodiment of the present invention. The cooling device 62 includes a conductive wiring pattern 63 extending from the power consumption circuit, that is, the CPU package 21 along the front surface of the printed circuit board 19, and heat dissipation mounted on the front surface of the printed circuit board 19 and connected to the conductive wiring pattern 63. Fins 64 are provided. The heat radiation fins 64 may be soldered to the conductive wiring pattern 63 on the printed circuit board 19, for example. Such a conductive wiring pattern 63 may be used as a ground wiring for the CPU package 21. In the figure, the same reference numerals are assigned to configurations that exhibit the same functions and functions as the configurations of the first embodiment described above.

  In the cooling device 62, the fan unit 38 a is attached to the front side surface of the printed circuit board 19. The fan unit 38a may have the same configuration as that of the fan unit 38 according to the first embodiment. The heat radiation fins 64 may be disposed in the exhaust port 46 of the fan unit 38a, for example. In addition, a conductive wiring pattern 63 extending from the CPU package 21 to the heat radiating fins 64 is stretched inside the fan case wall 46.

  According to such a cooling device 62, similarly to the above, heat radiation of the printed circuit board 19 is realized by the action of a high-speed air flow caused in the fan case 39 of the fan unit 38a. The conductive wiring pattern 63 greatly promotes heat dissipation of the printed circuit board 19. Moreover, since heat is efficiently transmitted from the CPU package 21 to the conductive wiring pattern 63, the CPU package 21 can be efficiently cooled.

  The air discharged from the exhaust port 46 takes heat away from the radiating fins 64. The air thus deprived of heat escapes from the opening 58 of the housing 57 to the outside of the device main body 12 as described above. Thus, efficient heat dissipation is realized in the heat dissipation fin 64. In addition, a conductive wiring pattern for grounding may be connected to the heat radiating fins 64 from other power consumption circuits such as the electronic components 24a, 24b.

  FIG. 8 shows a cooling device according to a third embodiment of the present invention. The cooling device 66 includes a fan unit 38 similar to that described above. In the fan unit 38, the electronic component 67 is mounted on the front surface of the printed circuit board 19 inside the fan case wall 45. The electronic component 67 may be disposed in the exhaust port 46 of the fan unit 38, for example. According to such a cooling device 66, similarly to the above, heat dissipation of the electronic component 67 can be realized by the action of a high-speed air flow caused in the fan case 39 of the fan unit 38. In the figure, the same reference numerals are assigned to configurations that exhibit the same functions and functions as the configurations of the first embodiment described above.

  The printed circuit board unit 18 with the cooling devices 27, 62, and 66 as described above is incorporated in a stationary electronic device in addition to the above-described portable electronic device such as the notebook computer 11 and the personal digital assistant (PDA). Also good. In the above-described fan units 38 and 38a, the bearing 52 of the rotating shaft 51 may be directly fixed to the printed circuit board 19.

It is a perspective view which shows roughly the external appearance of the notebook personal computer which concerns on one specific example of an electronic device. It is a top view which shows roughly the internal structure of an apparatus main body, and the front side surface of a printed circuit board unit. It is an enlarged plan view which shows the back side surface of a printed circuit board unit roughly. It is an enlarged plan view of the printed circuit board which shows roughly the principal part of the cooling device concerning a 1st embodiment of the present invention. FIG. 5 is an enlarged partial sectional view taken along line 5-5 of FIG. FIG. 6 is an enlarged partial cross-sectional view schematically showing a modification of the cooling device corresponding to FIG. 5. FIG. 5 is an enlarged plan view of a printed circuit board corresponding to FIG. 4 and schematically showing the configuration of a cooling device according to a second embodiment of the present invention. FIG. 6 is an enlarged plan view of a printed circuit board corresponding to FIG. 4 and schematically showing the configuration of a cooling device according to a third embodiment of the present invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 11 Notebook personal computer as electronic equipment, 18 Printed circuit board unit with cooling device, 19 Printed circuit board, 21 Electronic component and CPU (central processing unit) package as power consumption circuit, 27 Cooling device, 41 Ceiling wall, 42 Intake Port, 43 Rotating body constituting the fan, 44 Blade constituting the fan, 45 Wall for fan case, 47 Air inlet, 62 Cooling device, 63 Conductive wiring pattern, 64 Radiation fin, 66 Cooling device, 67 Electronic component, CR Rotation center.

Claims (7)

  A printed circuit board, a fan that rotates about the center of rotation intersecting the surface of the printed circuit board, a fan case wall that rises from the surface of the printed circuit board around the fan, and an exhaust port that is partitioned by the fan case wall body A printed circuit board unit with a cooling device.   2. The printed circuit board unit with a cooling device according to claim 1, wherein the ceiling wall is connected to an upper end of the fan case wall body and extends along a reference plane parallel to the surface of the printed circuit board, and formed on the ceiling wall. A printed circuit board unit with a cooling device, further comprising a suction port.   3. The printed circuit board unit with a cooling device according to claim 1, further comprising an air inlet that is formed in the printed circuit board inside the wall for the fan case. 4.   4. The printed circuit board unit with a cooling device according to claim 1, wherein the electronic component mounted on the printed circuit board extends along the surface of the printed circuit board inside the fan case wall, A printed circuit board unit with a cooling device, further comprising a conductive wiring pattern connected to the component.   5. The printed circuit board unit with a cooling device according to claim 4, further comprising a heat radiation fin attached to the printed circuit board and connected to the conductive wiring pattern.   The printed circuit board unit with a cooling device according to any one of claims 1 to 3, further comprising an electronic component mounted on a surface of the printed circuit board inside the fan case wall. Printed circuit board unit.   A printed circuit board, an electronic component mounted on the printed circuit board, a fan that rotates around a rotation center that intersects the surface of the printed circuit board, a wall for a fan case that rises from the surface of the printed circuit board around the fan, and a fan case An electronic device comprising an exhaust port defined by a wall for use.

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