Abstract:
A biaxial drive mechanism including a Z axis capable of realizing a high speed elevation axis without an increment in torque on a horizontal drive axes and a die bonder using the biaxial drive mechanism is disclosed. The biaxial drive mechanism includes a handling part; a first linear motor having a first movable part that moves up/down the handling part and a first stationary part; a second linear motor having a second movable part and a second stationary part; a connecting part that directly or indirectly connects the first movable part to the second movable part via the first linear guide; a second linear guide that moves the first movable part; and a support body that fixes the first stationary part and the second stationary part with a predetermined length in parallel to each other in the horizontal direction.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    The present invention relates to a biaxial drive mechanism including an elevation axis and a die bonder, and more particularly, to a high-speed bonding head as a biaxial drive mechanism including an elevation axis and a high-productivity die bonder. 
       DESCRIPTION OF RELATED ART 
       [0002]    A die bonder, which is one of semiconductor manufacturing devices, performs bonding of a semiconductor chip (die) to a substrate such as a lead frame. In the die bonder, a bonding head vacuum-sucks a die, then moves upward, then horizontally moves, then moves downward, and bonds the die to the substrate, at a high speed. In such case, a part for up and down movement is an elevation (Z) drive axis. 
         [0003]    Recently, there is an increasing need for high-accuracy and high-speed die bonder, and particularly, there is an increasing need for high-speed bonding head as the heart of bonding. 
         [0004]    A technique disclosed in Japanese Published Unexamined Patent Application No. 2004-263825 is known as a technique to respond to the above requirement. Generally, when a device operation speed is increased, vibration due to a high-speed moving body is increased, and with this vibration, target accuracy of the device cannot be attained without difficulty. According to Japanese Published Unexamined Patent Application No. 2004-263825, this vibration is reduced with a counter-reaction absorption device, to maintain the accuracy and attain the high operation speed. 
       SUMMARY OF THE INVENTION 
       [0005]    However, in the servo motor driving using a ball screw as in the case of Japanese Published Unexamined Patent Application No. 2004-263825, high-speed driving is limited. Accordingly, driving with a linear motor appropriate to high speed driving is studied. When a linear motor driving is merely adopted, stator and mover of a Z-axis drive liner motor both apply load on a Y drive axis in a horizontal direction e.g. Y direction to be described later as shown in  FIG. 7 . When the torque on the Y drive axis is increased, the electric power consumption is increased. When the weight of the stator and mover of a Z-axis drive linear motor is reduced, the torque on the Z axis is reduced and a predetermined high speed cannot be realized. 
         [0006]    Accordingly, the present invention has been made in consideration of the above situation, and provides a biaxial drive mechanism including a Z axis which realizes high sped elevation axis without increment in torque on a horizontal drive axis and a die bonder using the biaxial drive mechanism. 
         [0007]    To attain the above-described object, the present invention has at least the following features. 
         [0008]    According to the present invention, the first feature of the present invention is a biaxial drive mechanism comprising: a handling part; a first linear motor having a first movable part that moves up and down the handling part along a first linear guide and a first stationary part; a second linear motor having a second movable part that moves the handling part in a horizontal direction vertical to a direction of up and down movement and a second stationary part; a connecting part that connects the first movable part via the first linear guide and connects the second movable part directly or indirectly; a second linear guide that moves the first movable part, the second movable part and the connecting part integrally in the horizontal direction; and a support body that fixes the first stationary part and the second stationary part with a predetermined length in parallel to each other in the horizontal direction. 
         [0009]    Further, the second feature of the present invention is that the first movable part and the second movable part are provided in parallel or vertical to each other. 
         [0010]    Further, the third feature of the present invention is that the second linear guide is provided on the support body provided in a lower part of the second stationary part. 
         [0011]    Further, the fourth feature of the present invention is that the second liner guide is provided on the support body in an upper part of the connecting part. 
         [0012]    Further, the fifth feature of the present invention is that a plurality of pairs of alternate N pole and S pole electromagnets, provided in the direction of upward/downward movement in the first movable part, are provided in a predetermined region in the horizontal direction. 
         [0013]    Further, the sixth feature of the present invention is that a third linear guide is provided between the first stationary part or the second stationary part and the connecting part. 
         [0014]    Further, the seventh feature of the present invention is that the handling part in the biaxial drive mechanism in the first to sixth features performs processing on a substrate. 
         [0015]    Further, the eighth feature of the present invention is that the handling part is a bonding head that picks up a die from a wafer and bonds the die to the substrate, or a needle that applies a die adhesive to the substrate. 
         [0016]    Further, the ninth feature of the present invention is that the predetermined region is a region for pickup and a region for bonding. 
         [0017]    Further, the tenth feature of the present invention is that a rotation unit that rotates the handling part about the direction of up and down movement as a rotation axis is provided in the first movable part. 
         [0018]    In accordance with the present invention as described above, it is possible to provide a biaxial drive mechanism including a Z axis which realizes high sped elevation axis without increment in torque on a horizontal drive axis and a die bonder using the biaxial drive mechanism. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0019]    The above and other object, features and advantages of the present invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings wherein: 
           [0020]      FIG. 1  is a conceptual diagram showing a die bonder according a the first embodiment of the present invention viewed from an upper position; 
           [0021]      FIG. 2  is an A-A cross sectional diagram in a position where a bonding head on a ZY drive axes shown in  FIG. 1  exists; 
           [0022]      FIG. 3  illustrates the ZY drive axes shown in  FIG. 2  viewed from an arrow B direction; 
           [0023]      FIG. 4  schematically illustrates an example of the basic structure of left and right stationary magnets to move up/down the bonding head in a predetermined position; 
           [0024]      FIG. 5  illustrates the basic structure of a ZY drive axes  60 B according to a second embodiment of the present invention; 
           [0025]      FIG. 6  a illustrates the basic structure of a ZY drive axes  60 C according to a third embodiment of the present invention; and 
           [0026]      FIG. 7  illustrates a biaxial drive mechanism in which load is applied on a Z axis. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0027]    Hereinbelow, preferred embodiments of the present invention will now be described in accordance with the accompanying drawings. 
         [0028]      FIG. 1  is a conceptual diagram showing a die bonder  10  according to a first embodiment of the present invention viewed from an upper position. The die bonder  10  briefly has a wafer supply unit  1 , a work supply-conveyance unit  2  and a die bonding unit  3 . 
         [0029]    The wafer supply unit  1  has a wafer cassette lifter  11  and a pickup device  12 . The wafer cassette lifter  11 , having a wafer cassette (not shown) filled with wafer rings, sequentially supplies the wafer rings to the pickup device  12 . The pickup device  12  moves the wafer ring so as to pick up a desired die from the wafer ring. 
         [0030]    The work supply-conveyance unit  2  has a stack loader  21 , a frame feeder  22  and an unloader  23 . The work supply-conveyance unit  2  conveys a work (a substrate such as a lead frame) in an arrow direction. The stack loader  21  supplies a work, to which die is attached, to the frame feeder  22 . The frame feeder  22  conveys the work via two processing positions on the frame feeder  22  to the unloader  23 . The unloader  23  stores the conveyed work. 
         [0031]    The die bonding unit  3  has a preform unit (die paste applicator)  31  and a bonding head unit  32 . The preform unit  31  applies a die adhesive to the work conveyed with the frame feeder  22  such as a lead frame with a needle. The bonding head unit  32  picks up the die from the pickup device  12  then moves upward, and moves the die to a bonding point above the frame feeder  22 . Then the bonding head  32  moves down the die at the bonding point, and bonds the die to the work on which the die adhesive is applied. 
         [0032]    The bonding head unit  32  has a ZY drive axes  60  to elevate the bonding head  35  (see  FIG. 2 ) in a Z (height) direction then move the bonding head  35  in a Y direction, and an X drive axis  70  to move the bonding head  35  in an X direction. The ZY drive axes  60  has a Y drive axis  40  to move the bonding head  35  in the Y direction, i.e., between a pickup position in the wafer ring holder  12  and the bonding point, and a Z drive axis  50  to move the bonding head  35  upward to pick up the die from the wafer or for bonding on the substrate. The X drive axis  70  moves the entire ZY drive axes  60  in the X direction to convey the work. The X drive axis  70  may drive a ball screw with a servo motor or with a liner motor to be described in the structure of the ZY drive axes  60 . 
         [0033]    Hereinbelow, an embodiment of the ZY drive axes  60  as a feature of the present invention will be described using the drawings. 
         [0034]      FIGS. 2 and 3  illustrate a basic structure of a ZY drive axes  60 A according to the first embodiment. 
         [0035]      FIG. 2  is an A-A cross sectional diagram in a position shown in  FIG. 1  in which the bonding head  35  on the ZY drive axes  60  exists.  FIG. 3  illustrates the ZY drive axes  60 A shown in  FIG. 2  viewed from an arrow B direction. 
         [0036]    The ZY drive axes  60 A according to the first embodiment has the Y drive axis  40 , the Z drive axis  50 , a connecting part  61  to connect a Y axis movable part  41  of the Y drive axis  40  and a Z axis movable part  51  of the Z drive axis  50 , the bonding head  35  as a handling part, a rotation driving unit  80  to rotate the bonding head  35  about the Z axis, and an L-shaped support body  62  to support the entire ZY drive axes  60 A. Note that for assistance of understanding of the following explanation, a part fixed to the support body  62  is diagonally hatched, while a part to move integrally with the Y axis movable part  41 , the X axis movable part  51  and the connecting part  61  are represented in outline. Further, the support body  62  has an upper support body  62   a,  a side support body  62   b  and a lower support body  62   c.    
         [0037]    The Y drive axis  40  has a C-shaped Y axis stationary part  42  having upper and lower stationary electromagnets  47   u  and  47   d  in which a large number of N pole and S pole electromagnets are alternately arrayed in the Y direction (hereinafter, when the electromagnets are generally referred to or any position is not designated, simply denoted by “ 47 ”), the Y axis movable part  41 , having at least a pair of N pole and S pole electromagnets in the array direction, which is inserted in a C-shaped concave part and moved in the concave part, the connecting part  61  to support the Y axis movable part  41 , and a Y axis guide part  44  which is fixed to the connecting part  61 , and which has a Y axis linear guide  43  provided between the Y axis guide part and the lower support body  62   c.  The Y axis stationary part  42  is provided over approximately the whole area of the Y drive axis  40  indicated with a broken line in  FIG. 1  such that the Y axis movable part  41  can move in a predetermined range. 
         [0038]    Further, the Y axis linear guide  43  has two linear rails  43   a  extending in the Y direction and a linear slider  43   b  to move on the linear rails. 
         [0039]    As in the case of the Y drive axis  40 , the Z drive axis  50  has a U-shaped Z axis stationary part  52  having right and left stationary electromagnets  57   h  and  57   m  in which a large number of N pole and S pole electromagnets are alternately arrayed in the Z direction (see  FIG. 4 . Hereinafter, when the electromagnets are generally referred to or any position is not designated, simply denoted by “ 57 ”), the Z axis movable part  51 , having at least a pair of N pole and S pole electromagnets in the array direction of the Z axis stationary part  52  in an upper part, which is inserted in a U-shaped concave part and moved in the concave part, and a Z axis linear guide  53  having a similar structure to that of the Y axis linear guide  43  between the Z axis movable part  51  and the connecting part  61 . The Z axis linear guide  53  has two linear rails  53   a  fixed to the connecting part  61  and expanding in the Z direction and a linear slider  53   b  which is fixed to the Z axis movable part  51  and which moves on the linear rails. 
         [0040]    The Z axis movable part  51  is connected via the connecting part  61  to the Y axis movable part  41 . When the Y axis movable part  41  moves in the Y direction, the Z axis movable part  51  also moves in the Y direction. It is necessary to arrange such that the Z axis movable part  51  (bonding head  35 ) can move upward/downward in a predetermined position in the moving destination. 
         [0041]      FIG. 4  schematically illustrates an example of the structure of left and right stationary magnets  57  ( 57   h  and  57   m ) to move up/down the bonding head in a predetermined position. In the present embodiment, spindle N pole and S pole electromagnets are alternately provided at least in a bonding region and a pickup region, in the Y direction. The spindle N pole and S pole electromagnets may be divided into short pieces. It goes without saying that the spindle N pole and S pole electromagnets may be alternately provided in the Y direction over the entire region in the Y direction. 
         [0042]    The bonding head  35  is rotatably provided with the rotation driving unit  80  via a gear  35   b  at the end of the Z axis movable part  51 . The bonding head  35  has a collet  35   a  for die suction at its own end. Further, the rotation driving unit  80  controls the rotational attitude of the bonding head  35  via gears  82  and  35   b  with a motor  81  fixed to the Z axis movable part  51 . 
         [0043]    As described above, according to the ZY drive axes  60 A according to the present embodiment, the Z axis stationary part  52  is provided approximately over the entire region. In comparison with the structure shown in  FIG. 7 , as the Z axis stationary part  52  itself as a heavy body does not move, the load with respect to the movement in the Y direction can be greatly reduced. Thus it is possible to realize a high speed elevation axis without increment in torque on the horizontal drive axes. 
         [0044]      FIG. 5  illustrates the basic structure of a ZY drive axes  60 B according to a second embodiment. In  FIG. 5 , basically, constituent elements or functions the same as those in the first embodiment have the same reference numerals. 
         [0045]    The difference between the ZY drive axes  60 B and the ZY drive axes  60 A according to the first embodiment is that, first, the Y axis guide  44 , to support the Y axis linear guide  43  which enables Y-directional movement of the Y axis movable part  41 , moves from the lower support body  62   c  to the upper support body  62   a . Secondly, the Z axis stationary part  52  is not U-shaped but I-shaped, and in place of the stationary magnets  57   h  and  57   m,  only one Z axis stationary magnet  57  is used. 
         [0046]    The other elements are basically the same as those of the ZY drive axes  60 C according to the first embodiment. 
         [0047]      FIG. 6  illustrates the basic structure of a ZY drive axes  60 C according to a third embodiment. As in the case of  FIG. 5 , constituent elements or functions the same as those in the second embodiment have the same reference numbers. The difference between the ZY drive axes  60 C and the ZY drive axes  60 B according to the second embodiment is that, first, the Y axis stationary part  42  is I-shaped as in the case of the Z axis stationary part  52  according to the second embodiment, and the only one Y axis stationary magnet  47  is used,. Secondly, the Y axis movable-part fixing part  45  for fixing is provided on the Y axis movable part  41  and the connecting part  61 . Thirdly, to prevent leftward/rightward swing upon movement in the Y direction, the linear guide  46  is provided between the Y axis stationary part  42  and the connecting part  61 . 
         [0048]    Note that the linear guide  46  to stabilize such movement may be provided between the Y axis stationary part  42  or the Z axis stationary part  52  and the connecting part  61  in the first and second embodiments. 
         [0049]    The other elements are basically the same as those of the ZY drive axes  60 B according to the second embodiment. Note that as in the case of the third embodiment, the C-shaped Y drive axis  40  according to the first embodiment may be used. 
         [0050]    In the above-described second and third embodiments, as in the case of the first embodiment, in comparison with the structure shown in  FIG. 7 , as the Z axis stationary part  52  as a heavy body does not move, the load with respect to movement in the Y direction is greatly reduced. Thus it is possible to realize a high-speed elevation axis without increment in torque on a horizontal drive axes. 
         [0051]    In the above description, the example of a bonding head is used as a handling part to process something. Basically, the present invention is applicable to a necessary biaxial drive mechanism and a necessary handling part requiring an elevation axis. For example, in a die bonder, the present invention is applicable to a needle to apply a die adhesive to a substrate. 
         [0052]    The embodiments of the present invention have been described as above, however, various alternatives, modifications and equivalents can be made by those skilled in the art based on the above description, and it is intended for the subject matter of the invention to include all alternatives, modifications and equivalents within the spirit and scope of the following claims.