Patent Publication Number: US-6702000-B2

Title: Heat sink apparatus, blower for use therein and electronic equipment using the same apparatus

Description:
This is a divisional of application Ser. No. 08/624,990 filed Mar. 29, 1996 , now U.S. Pat. No. 6,315,031. 
    
    
     FIELD OF THE INVENTION 
     This invention relates to a blower for cooling heat generating parts in a casing of an electronic equipment such as a computer of desk-top type or portable or mobile type, and to a heat sink apparatus using the same blower. 
     DESCRIPTION OF THE RELATED ART 
     Followed by the recent tendency to large-scale integration and expedition, the amount of heat generated by the semiconductor such as a micro-processor unit (hereinafter, referred to as MPU) is increasing. In a personal computer and the like incorporating the MPU which generates a large amount of heat, there have been made various attempts such as to mount a heat sink for radiating heat or a heat sink having a built-in fan motor on an upper surface of the MPU for the purpose of suppressing a temperature rise in a casing. 
     FIG. 6 shows a dimensional relationship in a case where a heat sink having a built-in fan motor is mounted on an upper surface of the MPU. When the thicknesses of an MPU  71 , a printed circuit board  72  and a heat sink  73  having a built-in fan motor are 6 mm, 2 mm and 18 mm respectively, the overall thickness is 26 mm in total. Considering suction of air by the fan motor and insulation of the back of the printed circuit board, there is needed a space of at least 40 mm or so. 
     In an electronic equipment such as a notebook personal computer or the like, which is required to be thin, an interior space is limited to 30 mm. For this reason, it is impossible to insure an ample space above the upper surface of the MPU on the printed circuit board, and therefore it is impossible to mount a heat sink having a built-in fan motor on the upper surface of the MPU, giving rise to a problem in thermal design. 
     Meanwhile, in a desk-top personal computer, it is possible to insure a space above the upper surface of the MPU on the printed circuit board, however, there are needed to fan motors for a fan on the MPU and for another fan for exhaust of air from the casing, giving rise to a problem in cost. 
     SUMMARY OF THE INVENTION 
     In view of the above problems, a heat sink apparatus according to the present invention has a thermally conductive outer frame having a fan disposed in an opening thereof, the outer frame being mounted at one end of a heat conduction member for conducting heat of a heat generating device so as to conduct the heat to the vicinity of the fan to cool the heat generating device. Further, there is provided a heat sink apparatus of the invention that radiation fins are provided on the outer frame to cool the heat generating device more efficiently. 
     Moreover, a blower according to the present invention is provided with radiation fins having a fan drive section and a thermal conductivity on the side of a fan, adjacent to a heat generating device, within an opening of a thermally conductive outer frame, and therefore the blower can be made small size. 
     In addition, an electronic equipment according to the present invention includes a casing housing a circuit board having a heat generating device mounted thereon and a heat conduction member for conducting heat of the heat generating device therein, an outer frame having a thermal conductivity and provided with a fan disposed in an opening thereof, the outer frame being attached to the heat conduction member, and radiation fins having thermal conductivity and being provided on the outer frame, so as to remove the heat of the generating device through the heat conduction member, the outer frame and the fins. 
     With the above construction, the heat of the heat generating device is not only conducted and removed by making use of the outer frame of the fan and the radiation fins in the fan drive section but also cooled by the fan, and therefore the heat of the heat generating device can be removed effectively, and accordingly the equipment incorporating the heat generating device can be made smaller size. 
    
    
     BRIEF DESCRIPTION OF DRAWING 
     FIGS. 1A and 1B are perspective views of a blower according to the present invention; 
     FIG. 2 is a sectional view taken along the line II—II of FIG. 1; 
     FIG. 3 is a sectional view showing a construction of a heat sink apparatus in accordance with the invention; 
     FIG. 4 is a perspective view of an electronic equipment to which the heat sink apparatus of the invention is applied; 
     FIG. 5 is a sectional view taken along the line V—V of FIG. 4; and 
     FIG. 6 is a schematic side view of a conventional heat sink having a built-in fan motor. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     FIGS. 1A and 1B generally show a blower according to one embodiment of the present invention. FIG. 1A is a perspective view of the blower as viewed from the suction port side thereof, while FIG. 1B is a perspective view thereof from the exhaust port side thereof. 
     A blower  1  has an outer frame  3  made of a highly thermally conductive metal such as aluminum, copper or aluminum nitride. The outer frame  3  has an opening  5  in which a fan  7  is disposed. In the center of a suction port of the outer frame  3 , a bearing portion  11  which supports a rotary shaft  9  of the fan  7  is formed integrally with the outer frame  3 . On the suction port side of the outer frame  3 , a pair of attaching portions  17 , projecting from opposite side portions  13  of the outer frame  3  to extend beyond a suction surface  15 , are formed integrally with the outer frame  3 . In the vicinity of the suction port within the opening  5  of the outer frame  3 , radiation fins  19  are formed integrally with the outer frame  3 . The radiation fins  19  are arranged in the opening  5  thereof so as to surround the rotary shaft  9 . One of the side portions  13  of the outer frame  3  is formed with a slit  21  through which a lead wire  23  for electric power source is led out. A lead holder  25  is inserted in the slit  21  to prevent the lead wire  23  from coming out of the slit  21 . The radiation fins  19  may be formed separately from the outer frame  3  and fixed thereto by means of screws or the like. 
     FIG. 2 is a sectional view taken along the line II—II of FIG.  1 . 
     The rotary shaft  9  is fitted to the bearing portion  11  through ball bearings  27 , and the fan  7  is attached to one end of the rotary shaft  9 . A rotor yoke  29  and a magnet  31  are fixed to an inside of the fan  7 . A stator core  37  is attached to the bearing portion  11  within the opening  5 . A coil  35  is wound around a stator core  37  by way of an insulator  39  to which a base plate  33  of a fan-driving circuit is mounted. An insulator  39  is disposed between the coil  35  and the stator core  37 . The rotor yoke  29 , the magnet  31 , the fan base plate  33 , the coil  35  and the stator core  37  constitute a drive section for rotating the fan. 
     The radiation fins  19  are provided on the side of the blower  1  where the drive section of the fan  7  is arranged, and therefore the blower  1  can be made smaller. Further, the radiation fins  19  are provided in the vicinity of the suction port of the blower  1 , and therefore heat dissipation can be performed efficiently. 
     FIG. 3 shows a heat sink apparatus according to one embodiment of the present invention. 
     A micro-processor unit (hereinafter, referred to as MPU) 43, which is a heat generating device, is set on a lower surface of a printed circuit board  41 . The heat generating device is not limited to the MPU but may be another semiconductor such as a power IC. The MPU  43  is mounted on the printed circuit board  41  at one surface thereof and thermally connected at the other surface thereof to a radiation board  47 , which is a heat conduction member, through a radiation sheet  45  such as a silicon grease layer or a thermally conductive rubber sheet. Namely, the printed circuit board  41  and the radiation board  47  are fastened to each other with screws while leaving a predetermined space between them in such a manner that the heat of the MPU  43  is transferred to the radiation board  47 . The radiation board  47  is made of a highly thermally conductive metal such as aluminum, copper or aluminum nitride. The radiation board  47  is formed at one end thereof with a mounting portion  49  to which the blower  1  is fixed. The attaching portion  17  of the blower  1  is fastened to the mounting portion  49  of the radiation board  47  by means of a screw  51 . Namely, the blower  1  is fixed to the radiation board  47  in such a manner that the suction port of the blower  1  faces the MPU  43 . A thermally conductive grease  53  is applied between the mounting portion  49  of the radiation board  47  and the attaching portion  49  of the radiation board  47  and the attaching portion  17  of the blower  1  so as to increase the strength of thermal connection. The mounting portion  49  of the radiation board  47  and the attaching portion  17  of the blower  1  may be fastened to each other by other means such as soldering. Further, it is also possible to form the radiation board  47  and the outer frame of the blower  1  into one body by means of die casting or the like. 
     Heat generated from the MPU  43  is transfered through the radiation board  47  to the outer frame  3  and the radiation fins  19  of the blower  1 . The radiation board  47 , the outer frame  3  and the radiation fins  19  form a heat conduction path while each serving as a radiator device per se, thereby cooling the MPU  43 . The outer frame  3  and the radiation fins  19  of the blower  1  are forcedly cooled by the fan  7 , so that the radiation of heat can be effectively performed. Further, air currents produced by the fan  7  reach the MPU  43  and the radiation board  47  as well, and therefore the efficiency of radiation of heat from the surface of the MPU  43  and the radiation board  47  can be enhanced. 
     It is advisable that the radiation board  47  be formed in the shape of a plate, however, it is also possible to form a heat conduction member by making use of a heat pipe or the like. 
     FIG. 4 shows an electronic equipment according to one embodiment of the present invention. 
     A portable or mobile notebook personal computer  55  includes a base unit  57  which is a casing for housing a heat sink apparatus, and a display unit  59 . The base unit  57  has a keyboard  61  on an upper surface thereof. The display unit  59  is connected to a rear portion of the upper surface of the base unit  57  in such a manner that it pivots freely with respect to the base unit  57 . A liquid crystal display  63  is incorporated in the display unit  59 . The base unit  57  is formed with an exhaust port  67  in one side surface  65  thereof. 
     This embodiment is a portable or mobile computer, however, the present the present invention is applicable to a desk-top computer, a word processor, a portable terminal equipment and so on. 
     FIG. 5 is a sectional view taken along the line V—V of FIG.  4 . 
     A radiation board  69  as a heat conduction member is put on a bottom surface of a base unit  57  which constitutes the casing. A printed circuit board  71  is disposed above the radiation board  69  leaving a predetermined space between them. Both the radiation board  69  and the printed circuit board  71  are fastened to the base unit  57  by means of screws  73 . 
     The printed circuit board  71  is formed in a predetermined portion thereof with a through hole  75 . A projection  79  of a heat transfer block  77  serving as a heat transfer member, is inserted in the through hole  75  from below a lower surface of the printed circuit board  71 . The heat transfer block  77  is made of a highly thermally conductive metal such as an aluminum alloy. The heat transfer block  77  is fixed to the printed circuit board  71  by means of screws  81 . 
     A semiconductor chip  83  of tape-carrier-package type, or tape automated bonding type, which is a heat generating device, is put on an upper surface of the projection  79  of the heat transfer block  77 . The semiconductor chip  83  is fixed to the upper surface of the projection  79  by means of an electrically conductive bonding agent  85 . A lower surface of the heat transfer block  77  is thermally connected to the radiation board  69  through a radiation sheet  87 . 
     The radiation board  69  is provided at one end portion thereof, adjacent to the exhaust port  67 , with a mounting portion  89  to which the attaching portion  17  of the blower  1  is fixed by means of a screw  91 . A thermally conductive grease  93  is applied between the mounting portion  89  of the radiation board  69  and the attaching portion  17  of the blower  1  so as to enhance the efficiency of heat conduction between the mounting portion  89  and the attaching portion  17 . The attaching portion  17  of the blower  1  is fixed to the mounting portion  89  of the radiation board  69 , and therefore the suction port of the blower  1  faces the semiconductor chip  83  while the exhaust port of the blower  1  faces the exhaust port  67  of the base unit  57 . Heat generated from the semiconductor chip  83  put on the upper surface of the printed circuit board  71  is transferred by the heat transfer block  77  to the lower surface side of the printed circuit board  71 , and further transferred through the radiation sheet  87 , the radiation board  69 , the mounting portion  89  and the attaching portion  17  to the outer frame  3  and the radiation fins  19  of the blower  1 . The radiation board  69  and the outer frame  3  and the radiation fins  19  of the blower  1  form a heat conduction path while each serves as a radiator per se, thereby cooling the semiconductor chip  83 . The outer frame  3  and the radiation fins  19  are forcedly cooled by the fan  7 , and therefore the radiation of heat can be effectively performed. Further, air currents produced by the fan  7  reach the semiconductor chip  83  and the radiation board  69  as well, and accordingly the efficiency of radiation of heat from the surfaces of the semiconductor chip  83  and the radiation board  69  can be enhanced. 
     In this embodiment, the heat transfer block  77  is inserted in the through hole  75 , however, it is also possible to transfer the heat from the upper surface to the lower surface of the printed circuit board  71  by using a plated through hole alone. Further, the radiation board  69  as the heat conduction member is used in this embodiment, however it is also possible to transfer the heat to the blower by making use of a heat pipe or the like. 
     As has been described above, according to the present invention, the radiation fins are provided on the fan drive section side, and therefore the blower can be made small-sized. Further, the outer frame of the blower is made of a thermally conductive material and thermally connected to the heat conduction member, and therefore it is possible to materialize a heat sink apparatus and an electronic equipment which are compact and achieve high efficiency of heat radiation.