Abstract:
A mounting method for mounting an electronic component on a printed circuit board, the mounting method includes fixing a lower surface of a magnet panel to a magnetic body included in the electronic component by a magnetic force, seizing the electronic component by attracting a part of an upper surface of the magnet panel to an attaching unit, determining a position of the attracting unit to place the electronic component at a predetermined position with respect to the printed circuit board and releasing the attracting unit from the upper surface of the magnet panel.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application is based upon and claims the benefit of priority of the prior Japanese Patent Application No. 2008-256919 filed on Oct. 2, 2008, the entire contents of which are incorporated herein by reference. 
       FIELD 
       [0002]    A certain aspect of the embodiments discussed herein relates to an electronic component mounting method. 
       BACKGROUND 
       [0003]    As a technology to mount an electronic component on the printed board, there is a SMT (Surface Mount Technology). In the SMT, a printed board having a paste-state solder applied thereon for mounting a SMD (Surface Mount Device) is prepared. Then, the SMD is mounted on the printed board with a chip mounter. Subsequently, the solder is heated and melted in a high-temperature furnace (reflow furnace), and the SMD is welded on the printed board. 
         [0004]    As one of technologies for handling the electronic component with the chip mounter, there is a technology to handle the electronic component by attracting the same by a magnetic force with a magnet chuck. However, when using an electromagnet, a magnetic metal material is necessary on the side of the electronic component, so that it lacks general versatility in practical terms. 
         [0005]    As another technology to handle the electronic component with the chip mounter, there is a technology to handle the electronic component by attracting the same with a sucking head. The chip mounter employing this technology includes a sucking head which is movable between the position to arrange the printed board and the position to arrange the SMD. A sucking nozzle configured to attract the SMD is provided at a distal end of the sucking head. The chip mounter is able to transport the SMD to a predetermined position on the printed board by causing the attracting nozzle to attract the SMD. 
         [0006]    Since many electronic components have a flat surface on a top thereof, it is possible to attract the SMD by the sucking head. In addition, by changing the size of the sucking nozzle according to the size of the electronic component, it covers the electronic components in various sizes, so that the general versatility is secured. 
         [0007]    Incidentally, the SMD which is mounted on the printed board by the SMT includes large-sized electronic components such as a DC-DC (Direct Current-Direct Current) converter. When such large-sized SMD is mounted on the printed board with the chip mounter employing the sucking nozzle, if the position of attraction of the sucking nozzle is displaced from a center portion, the component is hard to been maintained horizontally, and hence it is difficult to position the sucking nozzle accurately to a predetermined position. Therefore, for the large-sized SMD, it is necessary to provide a flat portion at the center portion thereof for being attracted by the sucking nozzle. In general, productions design such as to secure a flat space on the center portion of the substrate or to arrange a component having a flat surface on the top thereof at the center of the SMD is desired. 
         [0008]    However, due to a constraint in productions design, there arise the following problems. 
         [0000]    1) Dead spaces tend to be formed, which hinders downsizing.
 
2) Arrangement of the component optimal in terms of electricity, cooling property, and structure cannot be achieved, which results in lowering of the function.
 
         [0009]    If the flat portion is hard to been formed in the center portion of the SMD, alternative means is desired. For example, a method of causing the SMD to be attracted to a double sucking nozzle (a head having two sucking nozzles) or a method of forming the flat portion by affixing an adhesive tape or the like is contemplated. Such methods have the following problems and hence the general versatility is not expected. 
         [0000]    3) The method of causing the SMD to be attracted to the double sucking nozzles requires special manufacturing equipment, and a burden of capital spending is excessive.
 
4) The method of forming the flat portion by affixing the adhesive tape or the like, a manner to affix the adhesive tape is difficult. In addition, an adhesive agent remains on the component side after a reflow, so that a number of steps are desired for removing the remained adhesive tape.
 
         [0010]    [Patent Document 1] Japanese Laid-open Patent Publication No. 56-152243 
         [0011]    [Patent Document 2] Japanese Laid-open Patent Publication No. 2001-267367 
       SUMMARY 
       [0012]    According to an aspect of an embodiment, a mounting method for mounting an electronic component on a printed circuit board, the mounting method includes fixing a lower surface of a magnet panel to a magnetic body included in the electronic component by a magnetic force, seizing the electronic component by attracting a part of an upper surface of the magnet panel to an attaching unit, determining a position of the attracting unit to place the electronic component at a predetermined position with respect to the printed circuit board and releasing the attracting unit from the upper surface of the magnet panel. 
         [0013]    The object and advantages of the invention will be realized and attained by means of the elements and combinations particularly pointed out in the claims. 
         [0014]    It is to be understood that both the forgoing general description and the following detailed description are exemplary and explanatory and are not respective of the invention, as claimed. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0015]      FIG. 1  is a drawing illustrating a procedure of manufacturing an electronic circuit module having a SMD mounted thereon. 
           [0016]      FIG. 2  is a drawing illustrating a mounting state of a magnet panel to the SMD. 
           [0017]      FIG. 3  is a drawing illustrating an example of a structure of a chip mounter. 
           [0018]      FIG. 4  is a drawing illustrating an attracting state by a sucking nozzle. 
           [0019]      FIG. 5  is a drawing illustrating a printed board on which the SMD is mounted. 
           [0020]      FIG. 6  is a drawing illustrating the printed board on which the SMD is soldered. 
           [0021]      FIG. 7  is a drawing illustrating a state after removal of the magnet panel. 
           [0022]      FIG. 8  is a drawing illustrating a mounting state of the magnet panel on the stud on the SMD. 
           [0023]      FIG. 9  is a drawing illustrating the attracting state by the attracting nozzle. 
       
    
    
     DESCRIPTION OF EMBODIMENTS 
       [0024]    Referring now to the drawings, embodiments of the present invention will be described. 
         [0025]    A first embodiment is configured in such a manner that a magnet panel is fixed on a magnetic component on a SMD by a magnetic force. 
         [0026]      FIG. 1  is a drawing depicting a procedure of manufacturing an electronic circuit module having the SMD mounted thereon. First of all, a magnet panel  20  is mounted on a large-sized SMD  10  (Step S 1 ). The magnetic component including a magnetic substance is mounted on the SMD  10 , and the magnet panel  20  is fixed to the magnetic component by the magnetic force. The magnet panel  20  is a panel-shaped permanent magnet. 
         [0027]    Subsequently, the SMD  10  and a printed circuit board  30  are mounted at predetermined positions of a chip mounter (Step S 2 ). For example, the SMD  10  is arranged in a tray for chip mounter components. The printed circuit board  30  is installed at an electronic component mounting position by a substrate transfer mechanism (loader). Paste-state solders  31 ,  32  are applied on an upper surface of the printed circuit board  30 . In this embodiment, the surface on the side on which the SMD  10  is to be mounted by reflow soldering is referred to as the “upper surface” of the printed circuit board  30 . 
         [0028]    Subsequently, the SMD  10  is mounted on the printed circuit board  30  with the chip mounter (Step S 3 ). In this case, to lift the SMD  10 , the chip mounter attracts a center portion of the upper surface of the magnet panel  20  mounted on the upper portion of the SMD  10 . Then, the chip mounter positions the SMD  10  at a predetermined position on the printed circuit board  30 . The chip mounter releases a nozzle of the chip mounter from the upper surface of the magnet panel so as to leave the SMD  10  on the printed circuit board  30 . 
         [0029]    Subsequently, reflow soldering is performed (Step S 4 ). In other words, the printed circuit board  30  having the SMD  10  mounted thereon is delivered to a reflow furnace and, in the reflow furnace, hot air is blown onto the printed circuit board  30 . Accordingly, the SMD  10  is soldered to the printed circuit board  30 . Finally, the magnet panel  20  is removed from the SMD  10  (Step S 5 ). 
         [0030]    The electronic circuit module having the SMD  10  mounted thereon is manufactured in this procedure. 
         [0031]    The permanent magnet used in the magnet panel  20  includes ferrite magnet, samarium-cobalt magnet, and neodymium magnet, for example. The permanent magnet used in the magnet panel  20  is determined according to the weight of the SMD  10 , the size of the magnetic component, and ease of becoming magnetized. For example, if the magnetic component is small, a permanent magnet having a strong magnetic force such as the neodymium magnet or samarium-cobalt magnet is used as the magnet panel  20 . 
         [0032]    When the maintenance of the magnetic force after being subjected to the reflow soldering is considered, for example, a substance having a high maximum usable temperature such as samarium-cobalt magnet is suitable for the magnetic panel  20 . If the magnetic force of the magnet panel  20  is sufficiently maintained after the reflow soldering, repetitive usage of the magnet panel  20  is achieved. 
         [0033]    A method of mounting the SMD will be described in detail. 
         [0034]      FIG. 2  is a drawing depicting a mounting state of a magnet panel to the SMD. An electronic component including an inductor  11  and a transformer  12  is mounted on top of the SMD  10 . The inductor  11  and the transformer  12  are magnetic components. In other words, the inductor  11  and the transformer  12  have a property to be attracted to a magnet. Also, the inductor  11  and the transformer  12  have a height higher than other electronic components mounted on the SMD  10 , so that they come into direct contact with the magnet panel  20  when the magnet panel  20  is put thereon from above. Leads  13  to  18  are provided under the SMD  10 . 
         [0035]    The magnet panel  20  formed of the permanent magnet is mounted on top of the SMD  10  having the configuration as described above. The magnet panel  20  has two different polarities divided in the vertical direction. In other words, if the upper surface of the magnet panel  20  is an N-pole, a lower surface is an S-pole. In contrast, if the upper surface is the S-pole, the lower surface is the N-pole. 
         [0036]    In  FIG. 2 , although the magnet panel  20  has a rectangular shape, it may have a circular shape or other shapes. The upper surface of the magnet panel  20  has a flat area having at least a surface area of an extent which allows a sucking nozzle of the chip mounter to be attracted thereto secured as a nozzle attracting point  21 . The nozzle attracting point  21  is provided above the center of gravity of a mass system including the magnet panel  20  and the SMD  10 . By causing the sucking nozzle to be attracted to the nozzle attracting point  21  above the center of gravity, the SMD  10  may be maintained horizontally when moving the SMD  10 . Since the magnet panel  20  may be formed of a homogeneous substance (the center of gravity may be set at the center of the magnet panel  10 ), if the center of gravity of the SMD  10  by itself is positioned substantially at the center of the SMD  10 , the nozzle attracting point  21  comes to the center portion of the magnet panel  20 . 
         [0037]    The lower surface of the magnet panel  20  is preferably flat at least an area which comes into contact with the inductor  11  and the transformer  12 . However, if a sufficient magnetic force for lifting and moving the SMD  10  is secured, the area which comes into contact with the inductor  11  and the transformer  12  does not have to be completely flat. For example, there may be pits and projections or a curve to some extent on the lower surface of the magnet panel  20 . 
         [0038]    When the magnet panel  20  in this configuration is arranged on the upper surface of the SMD  10 , the magnet panel  20  and the magnetic components (the inductor  11  and the transformer  12 ) attract to each other by the magnetic force. Consequently, the magnet panel  20  is fixed to the upper surface of the SMD  10 . 
         [0039]    Subsequently, the SMD  10  with the magnet panel  20  fixed thereon is mounted on the chip mounter. 
         [0040]      FIG. 3  is a drawing depicting an example of a structure of the chip mounter. A chip mounter  100  includes a sucking head  110  configured to attract the SMD  10  and place the same on the printed circuit board  30 . The sucking head  110  is able to attract the magnet panel  20  by the sucking nozzle provided at a distal end thereof. 
         [0041]    The sucking head  110  is movably mounted on a Z-axis transfer unit  121 . The Z-axis transfer unit  121  moves the sucking head  110  in the vertical direction (in a Z-axis direction) according to an instruction from a control unit  150 . The Z-axis transfer unit  121  is movably mounted on an X-axis transfer unit  122 . The X-axis transfer unit  122  moves the Z-axis transfer unit  121  in a X-axis direction according to an instruction from the control unit  150 . The X-axis transfer unit  122  is movably mounted on an Y-axis transfer unit  123 . The Y-axis transfer unit  123  moves the X-axis transfer unit  122  in a Y-axis direction according to an instruction from the control unit  150 . 
         [0042]    The chip mounter  100  has a fixed position for installing a component tray  130 . The component tray  130  is installed at a predetermined position in the state in which a plurality of SMDs  10  are stored. A substrate transfer unit  140  transfers the printed circuit board  30  according to an instruction from the control unit  150 . 
         [0043]    The control unit  150  controls the action of the entire chip mounter  100  in response to an instruction to mount the SMD  10  by an operation input. More specifically, the control unit  150  controls the substrate transfer unit  140  after having set the component tray  130  having the SMDs  10  stored therein to move the printed circuit board  30  to the predetermined position. Subsequently, the control unit  150  controls the Z-axis transfer unit  121 , the X-axis transfer unit  122 , and the Y-axis transfer unit  123  to move the sucking head  110  to a position of the predetermined SMD  10  in the component tray  130 . In addition, the control unit  150  controls the sucking head  110  to cause the same to attract the magnet panel  20  fixed on top of the SMD  10 . Since the magnet panel  20  and the SMD  10  are fixed by the magnetic force, the SMD  10  is moved in association with the sucking head  110  from then on. 
         [0044]    After having caused the sucking head  110  to attract the magnet panel  20 , the control unit  150  controls the Z-axis transfer unit  121 , the X-axis transfer unit  122 , and the Y-axis transfer unit  123  to position the SMD  10  to a predetermined position on the printed circuit board  30 . Subsequently, the control unit  150  controls the sucking head  110  to release the magnetic panel  20  attracted to the sucking head. 
         [0045]    In this manner, an automatic mounting of the SMD  10  to the printed circuit board  30  by the chip mounter  100  is performed. 
         [0046]      FIG. 4  is a drawing depicting condition where the sucking nozzle is attracting the magnet panel. When the sucking head  110  is moved to the position of the SMD  10 , a sucking nozzle  111  is positioned so that the sucking nozzle  111  at the distal end of the sucking head  110  matches the nozzle attracting point  21  on the upper surface of the magnet panel  20  (see  FIG. 2 ). Then, the magnet panel  20  is attracted to the nozzle attracting point  21 . In other words, the chip mounter  100  decompresses the interior of the sucking nozzle  111  to produce a vacuum. 
         [0047]    Accordingly, the sucking nozzle  111  and the magnet panel  20  are attracted to each other. 
         [0048]    Since the magnet panel  20  is fixed to the inductor  11  and the transformer  12  by the magnetic force, if the magnet panel  20  is lifted upward by the sucking nozzle  111 , the SMD  10  is also lifted simultaneously. Therefore, the chip mounter  100  moves the sucking head  110  and positions the SMD  10  onto the printed circuit board  30 . 
         [0049]      FIG. 5  is a drawing depicting a printed board on which the SMD is mounted. The SMD  10  is positioned so that the leads  15 ,  18  come on top of the solders  31 ,  32  on the printed circuit board  30 . The chip mounter  100  breaks the vacuum in the interior of the sucking nozzle  111  to release the magnet panel  20  from the sucking nozzle  111 . 
         [0050]    The printed circuit board  30  having the SMD  10  mounted thereon is put into the reflow furnace and heated. Then, the solders  31 ,  32  melt. Then, the temperature of the printed circuit board  30  is lowered by cold air. Consequently, the leads  13  to  18  of the SMD  10  are soldered to the printed circuit board  30 . 
         [0051]      FIG. 6  is a drawing depicting the printed board on which the SMD is soldered. The leads  15 ,  18  of the SMD  10  are joined by the solders  31 ,  32  provided on the printed circuit board  30 . Although not depicted, other leads  13 ,  14 ,  16  and  17  (see  FIG. 2 ) are also joined by the solder. Subsequently, the magnet panel  20  fixed to the SMD  10  is removed. 
         [0052]      FIG. 7  is a drawing depicting a state after removal of the magnet panel. Since the SMD  10  is fixed firmly to the printed circuit board  30  by the solders  31 ,  32 , the magnet panel  20  can be separated from the SMD  10  by pulling the magnet panel  20  from above. 
         [0053]    As described above, by joining the magnet panel  20  with the magnetic components (the inductor  11 , the transformer  12 ) on the large-sized SMD  10 , even though there is no space to allow the nozzle to attract at the center portion of the SMD  10 , automatic mounting of the SMD  10  on the printed circuit board  30  is achieved by the chip mounter  100  using a nozzle attracting mechanism. 
         [0054]    Accordingly, an optimal arrangement of the components is achieved without considering the position to allow the sucking nozzle to attract, and formation of the dead spaces is eliminated. Consequently, easy downsizing of the SMD is achieved. 
         [0055]    Also, optimization of the arrangement of the components is achieved in terms of the electricity, the cooling property, and the structure. Consequently, the improvement of the function of the SMD is expected. 
         [0056]    Also, removal of the magnet panel  20  is easily achieved after the reflow. In other words, attachment and detachment of the magnet panel are easy. In addition, since such event that the adhesive agent remains thereon does not occur, the operation to remove the adhesive agent is not necessary and the number of steps is significantly reduced in comparison with the case in which the flat portion is formed by affixing the adhesive agent. 
         [0057]    In addition, a special manufacturing equipment such as the double nozzle chip mounter does not have to be prepared. In other words, the chip mounter  100  having a single nozzle in the related art may be used. Therefore, a large-scale additional investment is not necessary. 
         [0058]    The SMD  10  having the magnetic substance may be mounted on the printed board by the chip mounter configured to handle the electronic component by a magnetic chuck formed of an electromagnet. However, a mounter in which the magnet chuck is employed can hardly handle various types of SMDs. In contrast, with the mounting method according to this embodiment, various sizes of the SMDs may be mounted by the single chip mounter  100  including the sucking head used therein only by mounting the magnet panel  20  on the large-sized SMD  10 . Therefore, the general versatility of the chip mounter  100  including the sucking head used therein is further enhanced. 
         [0059]    In a second embodiment, with the provision of a stud having a property to be attracted to the SMD (for example, iron), the binding power between the magnet panel and the SMD is enhanced. 
         [0060]      FIG. 8  is a drawing depicting a mounting state of the magnet panel on the stud on the SMD. An electronic component including an inductor  51  and a transformer  52  is mounted on top of a circuit substrate of a SMD  50 . Leads  53  to  58  are provided under the SMD  50 . Studs  61 ,  62  are mounted on a pair of corners in a diagonal relationship on top of the circuit substrate of the SMD  50 . 
         [0061]    The studs  61 ,  62  are column shaped magnetic substances. For example, ferromagnetic material such as iron is used as the studs  61 ,  62 . The studs  61 ,  62  depicted in  FIG. 8  have a square pole shape. However, studs in a circular column shape may be used as well. 
         [0062]    The studs  61 ,  62  have a height not lower than the inductor  51  and the transformer  52 . Accordingly, when the magnet panel  20  is put thereon, the studs  61 ,  62  and the magnet panel  20  are in direct contact with each other, so that enhancement of the magnetic forces attracting each other is achieved. 
         [0063]    The magnet panel  20  formed of the permanent magnet is mounted on top of the SMD  50  having the configuration as described above. The studs  61 ,  62  are magnetized by a magnetic field generated by the magnet panel  20 . The studs  61 ,  62  and the magnet panel  20  are attracted by each other, and the magnet panel  20  is fixed to the SMD  50 . 
         [0064]      FIG. 9  is a drawing depicting a condition where the sucking nozzle is attracting the magnet panel. A sucking nozzle  111  is attracted to the nozzle attracting point  21  (see  FIG. 8 ) of the magnet panel  20 . 
         [0065]    With the provision of the studs  61 ,  62  on the SMD  50  in this manner, the magnet panel  20  may be bound even though there is no adequate magnetic component on the SMD  50 . The steps from then on are the same as those in the first embodiment depicted in  FIG. 1 . 
         [0066]    In the example depicted in  FIGS. 8 and 9 , the studs  61 ,  62  are provided only on one pair of corners in a diagonal relationship of the SMD  50 , the studs may be provided at all the corners. 
         [0067]    Permanent magnets may be used as the studs  61 ,  62 . In this case, they are mounted in such a manner that the magnetic pole which attracts the magnetic pole of the lower surface of the magnet panel  20  comes on the upper side of the studs  61 ,  62 . 
         [0068]    In addition, in the example depicted in  FIGS. 8 and 9 , the studs  61 ,  62  are provided on the SMD  50 . However, a configuration in which the studs are provided on the opposite corners on the lower surface of the magnet panel  20  is also possible. In this case, pads formed of the magnetic substance are provided at least at the pair of corners in a diagonal relationship (positions which match the studs of the magnet panel  20 ) on the upper surface of the SMD  50 . 
         [0069]    In this manner, with the provision of the studs  61 ,  62  in advance on the SMD  50 , the fixation of the magnet panel  20  is achieved even though the magnetic component is not included in the components to be mouthed in order to realize the function of the SMD  50 . 
         [0070]    As described in the embodiments depicted above, by mounting the magnet panel on the SMD and causing the magnet panel to be attracted by the sucking nozzle, the dead space formed on the SMD is minimized, so that downsizing of the SMD product is easily achieved. 
         [0071]    Incidentally, there is a case where makers of the electronic circuit module purchases SMDs from external dealers and mounts the purchased SMDs on printed boards in their own factories. In such a case, manufacturers of the SMDs may mount the magnet panels on top of the SMDs. In other words, the manufactures of the SMDs deliver the SMDs in the form having the magnet panel mounted on top thereof to the makers of the electronic circuit modules. Accordingly, the makers of the electronic circuit modules are able to save themselves a work to mount the magnet panels. 
         [0072]    The present invention is not limited to the embodiments described above, and various modifications may be made without departing from the scope of the invention. 
         [0073]    All examples and conditional language recited herein are intended for pedagogical purposes to aid the reader in understanding the invention and the concepts contributed by the inventor to furthering the art, and are to be construed as being without limitation to such specifically recited examples and condition, nor does the organization of such examples in the specification relate to a showing of superiority and inferiority of the invention. Although the embodiment of the present inventions have been described in detail, it should be understood that the various changes, substitutions, and alternations could be made hereto without departing from the spirit and scope of the invention.