Abstract:
A highly reliable biaxial drive mechanism and a die bonder operating method capable of preventing fall of an elevation axis of a linear motor upon loss of power are disclosed. The biaxial drive mechanism includes a handling part; a biaxial drive axes provided with a first linear motor unit having a first movable part that moves up and down the handling part along a first linear guide and a first stationary part, and a second linear motor unit 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 main power source that supplies a power source to the biaxial drive axes; and an elevation axis fall prevention unit that prevents fall of a handling part upon loss of power at the main power source.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    The present invention relates to a biaxial drive mechanism including an elevation axis and a die bonder using the biaxial drive mechanism and a die bonder operating method, and more particularly, to a highly reliable biaxial drive mechanism including an elevation axis and a highly reliable die bonder using the biaxial drive mechanism and a die bonder operating method. 
       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]    As a conventional bonding head driving method, driving a ball screw with a servo motor is known (Japanese Published Unexamined Patent Application No. 2004-263825). 
       SUMMARY OF THE INVENTION 
       [0005]    However, in the method of driving a ball screw with a servo motor, 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, the elevation axis can be easily manually-operated upon loss of power. As shown in  FIG. 4B , in some cases, the bonding head as a handling part falls on a substrate (processing subject) such as a lead frame, and the bonding head is broken, and further, the substrate, i.e., the product is also broken. 
         [0006]    Accordingly, the present invention has been made in consideration of the above situation, and provides a highly reliable biaxial drive mechanism including an elevation axis and a highly reliable die bonder using the biaxial drive mechanism and a die bonder operating method capable of preventing fall of elevation axis of a linear motor upon loss of power. 
         [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 biaxial drive axes provided with a first linear motor unit having a first movable part that moves up and down the handling part along a first linear guide and a first stationary part, and a second linear motor unit 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 main power source that supplies a power source to the biaxial drive axes; and an elevation axis fall prevention unit that prevents fall of a movable part of a handling part upon loss of power at the main power source. 
         [0009]    Further, the second feature of the present invention is that the biaxial drive axes has: 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. 
         [0010]    Further, the third feature of the present invention is that the biaxial drive axes has a third linear guide that fixes the first linear motor unit to the second movable part, and guides movement of the first linear motor unit in the horizontal direction. 
         [0011]    Further, the fourth feature of the present invention is that the elevation axis fall prevention unit has: a stopper provided on a first movable body to move along with the first movable part; and a support drive part that supports the stopper in a predetermined position upon loss of power. 
         [0012]    Further, the fifth feature of the present invention is that the support drive part is provided on the first stationary part, otherwise, the support drive part is provided on both end sides of the second stationary part or other stationary part around the second stationary part. 
         [0013]    Further, the sixth feature of the present invention is that the support drive part is a solenoid having a bar to be able to protrude in accordance with presence/absence of power source or an air cylinder having a cylinder rod. 
         [0014]    Further, the seventh feature of the present invention is that a supporting operation to support in the predetermined position is performed with another power source provided in addition to the main power source. 
         [0015]    Further, the eighth feature of the present invention is that a controller that moves up the first movable part or maintains the first movable part in its current status with another power source provided in addition to the main power source upon loss of power is provided. 
         [0016]    Further, the ninth feature of the present invention is that the biaxial drive mechanism in the first to eighth features is provided, and the handling part performs processing on a substrate. 
         [0017]    Further, the tenth 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. 
         [0018]    Further, the eleventh feature of the present invention is comprising: providing a main power source; a step of moving up a bonding head with a linear motor unit by supply of a main power source to pick up a die and bond the die to a substrate; and a fall prevention step of upon loss of power at the main power source, preventing fall of the bonding head. 
         [0019]    In accordance with the present invention as described above, it is possible to provide a highly reliable biaxial drive mechanism including an elevation axis and a highly reliable die bonder using the biaxial drive mechanism and a die bonder operating method capable of preventing fall of elevation axis of a linear motor upon loss of power. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0020]    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: 
           [0021]      FIG. 1  is a conceptual diagram showing a die bonder according to a first embodiment of the present invention viewed from an upper position; 
           [0022]      FIG. 2  is an A-A cross sectional diagram showing a basic structure of a ZY drive axes according to a first embodiment, and a first embodiment of an elevation axis fall prevention unit, in a position in  FIG. 1  in which a bonding head on the ZY drive axes exists; 
           [0023]      FIG. 3  illustrates the ZY drive axes shown in FIG.  2  viewed from an arrow B direction; 
           [0024]      FIGS. 4A and 4B  illustrate statuses of the bonding head upon loss of power; 
           [0025]      FIG. 5  is a conceptual diagram showing the die bonder according to a second embodiment of the present invention viewed from an upper position; 
           [0026]      FIGS. 6A and 6B  illustrate the basic structure of the ZY drive axes and the elevation axis fall prevention unit according to the second embodiment; 
           [0027]      FIG. 7  illustrates a status of the elevation axis fall prevention unit according to the second embodiment upon loss of power; 
           [0028]      FIGS. 8A and 8B  illustrate other positions than a position in which a solenoid is provided in the elevation axis fall prevention unit according to the first and second embodiments; 
           [0029]      FIGS. 9A to 9C  illustrate the elevation axis fall prevention unit according to a third embodiment; 
           [0030]      FIGS. 10A and 10B  illustrate the elevation axis fall prevention unit according to a fourth embodiment; 
           [0031]      FIG. 11  illustrates a status of the elevation axis fall prevention unit according to the fourth embodiment upon loss of power; and 
           [0032]      FIGS. 12A and 12B  illustrate the elevation axis fall prevention unit according to a fifth embodiment. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0033]    Hereinbelow, preferred embodiments of the present invention will now be described in accordance with the accompanying drawings. 
         [0034]      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 , a die bonding unit  3 , a power source unit  9 , and a controller  7  to control these units. 
         [0035]    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. 
         [0036]    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 bonded, 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. 
         [0037]    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 horizontally 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. 
         [0038]    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 horizontally move the bonding head  35  in a Y direction, and an X drive axis  70  to horizontally 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 . 
         [0039]    The power source unit  9  has a main power source  91  used in normal packaging processing and another battery  92  as a power source different from the main power source, necessary for prevention of fall of an elevation axis to be described later in detail. 
         [0040]      FIGS. 2 and 3  illustrate a basic structure of the ZY drive axes  60  according to the first embodiment and the elevation axis fall prevention unit according to the first embodiment.  FIG. 2  is an A-A cross sectional diagram in  FIG. 1  showing the bonding head  35  existing at the end of the ZY drive axes  60 .  FIG. 3  illustrates the ZY drive axes  60  shown in  FIG. 2  viewed from an arrow B direction. 
         [0041]    First, the ZY drive axes  60  including the elevation axis according to the first embodiment as a feature of the present invention will be described using the drawings. 
         [0042]    The ZY drive axes  60  according to the first embodiment has a Y drive axis  40 , a 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, an elevation axis fall prevention unit  80  to prevent fall of the bonding head  35  upon loss of power, and an L-shaped support body  62  to support the entire ZY drive axes  60 . 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.    
         [0043]    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. 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. 
         [0044]    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. 
         [0045]    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  horizontally moves in the Y direction, the Z axis movable part  51  also horizontally moves in the Y direction. It is necessary to provide N pole and S pole electromagnets in at least moving destination predetermined positions, e.g., a bonding region and a pickup region, such that the Z axis movable part  51  (bonding head  35 ) moves up and down. Note that a part to move up and down integrally with the Z axis movable part  51  is referred to as a Z axis movable body. 
         [0046]    Next, the elevation axis fall prevention unit  80  according to the first embodiment as one of the characteristic features of the present invention will be described with reference to  FIGS. 2 ,  3  and  FIGS. 4A and 4B .  FIGS. 4A and 4B  illustrate statuses of the bonding head  35  upon loss of power.  FIG. 4A  illustrates a status when the elevation axis fall prevention unit  80  is provided; and  FIG. 4B , a status when the elevation axis fall prevention unit  80  is not provided. 
         [0047]    The elevation axis fall prevention unit  80  according to the first embodiment has a stopper  81  fixed to the linear slider  53   b  to move up/down the bonding head  35 , a pusher solenoid  82  as a support drive part fixed to the connecting part  61  as shown in  FIG. 3 , in which a protrusion part of a push bar  82   a  is prolonged upon loss of power so as to support the stopper  81 , and another power source  92  shown in  FIG. 1 . 
         [0048]    In the elevation axis fall prevention unit  80  having the above structure, the controller  7  detects loss of the main power source  91  upon loss of power, connects the other power source  91  to the pusher solenoid  82  while the power source is maintained with a capacitor or the like, and supplies the power source. 
         [0049]    As a result, as shown in  FIG. 4A , the pusher solenoid  82  is activated, then the push bar  82   a  is protruded, to support the stopper  81 , to prevent fall of the bonding head  35  on a substrate P. 
         [0050]    According to the above-described first embodiment of the elevation axis fall prevention unit  80  of the present invention, upon loss of power at the main power source  91 , it is possible to activate the pusher solenoid with another power source so as to prevent fall of the bonding head having the elevation axis of the linear motor. 
         [0051]    As a result, it is possible to prevent breakage of the bonding head and the substrate. 
         [0052]    Further, according to the above-described first embodiment of the ZY drive axes  60  in the invention, the Z axis stationary part  52  is provided in approximately the whole region, but the Z axis stationary part  52  is a heavy body and the Z axis stationary part  52  itself does not move. Accordingly, the load on the movement in the Y direction is greatly reduced, and it is possible to realize a high-speed elevation axis without increment in torque on a horizontal drive axis. 
         [0053]    Next,  FIG. 5  is a conceptual diagram showing the die bonder  10 A according to a second embodiment of the present invention viewed from an upper position. The difference between the die bonder  10  according to the first embodiment and the die bonder  10 A according to the second embodiment is that the ZY drive axes and the elevation axis fall prevention unit are different. The other elements are basically the same as those in the first embodiment. In the second embodiment, the constitute elements having basically the same structures or functions as those in the first embodiment have the same reference numerals. 
         [0054]    In a ZY drive axes  60 A according to the second embodiment, a Z drive axis  50 A is basically different from the ZY drive axes  60  according to the first embodiment. In the ZY drive axes  60  according to the first embodiment, the Z axis stationary part  52  of the Z drive axis  50  as an elevation axis is provided in the whole region of the moving range as in the case of the Y axis stationary part  42 . The Z axis movable part  51  moves integrally with the Y axis movable part  41 . 
         [0055]    On the other hand, in the Z drive axis  50 A according to the second embodiment, Z axis stationary part  52 A and the Z axis movable part  51 A move integrally with the Y axis movable part  41 A in an arrow C direction in  FIG. 5 . The shapes of the Y axis stationary part  42 A and the Y axis movable part  41 A forming the Y drive axis  40 A according to the second embodiment, the connection direction of the Z drive axis  50 A to the Y drive axis  40 A are different from those in the first embodiment, however, the basic structural functions are the same. 
         [0056]      FIGS. 6A and 6B  illustrate the basic structure of the ZY drive axes and the elevation axis fall prevention unit according to the second embodiment.  FIG. 6A  illustrates the ZY drive axes  60 A viewed from an arrow D direction in a position where the bonding head  35  exists in  FIG. 5 .  FIG. 6B  illustrates the ZY drive axes  60 A shown in  FIG. 6A  viewed from an upper direction. Note that in  FIG. 6B , the support body  62  and the Y axis linear guide  43  shown in  FIG. 6A  are omitted. Further, in  FIGS. 6A and 6B , the stationary electromagnets  47  and  57  in  FIGS. 2 and 3  are omitted. 
         [0057]    The ZY drive axes  60 A according to the second embodiment has the Y drive axis  40 A, the Z drive axis  50 A, the bonding head  35  as a handling part, an elevation axis fall prevention unit  80 A to prevent fall of the bonding head  35  upon loss of power, and the support body  62  to support these elements. 
         [0058]    As in the case of the first embodiment, the Y drive axis  40 A has the C-shaped Y axis stationary part  42  which is fixed to the support body  62  and which has an opening  42   a  on the front side, and the Y axis movable part  41  which is inserted from the opening  42   a  in the concave part of the Y axis stationary part  42  and which moves in the concave part. The Y axis stationary part  42  is provided over approximately the whole region of the Y drive axis  40 A indicated with a broken line in  FIG. 5  such that the Y axis movable part  41  can move within a predetermined range. 
         [0059]    As in the case of the Y drive axis  40 A, the Z drive axis  50 A has the C-shaped Z axis stationary part  52 , the Z axis movable part  51  which is inserted in the C-shaped concave part and which moves in the concave part, a connecting part  54  to connect the Z axis movable part  51  and the bonding head  35 , the Z axis linear guide  53  to guide up and down movement of the bonding head  35  in accordance with up and down movement of the Z axis movable part  51 A, a holding body  55  to fix and hold these elements, and the Y axis linear guide  43  to guide the entire horizontal movement of the holding body  55 , i.e. the Z drive axis  50 A in accordance with the horizontal movement of the Y axis movable part  41  in the Y direction. The Z axis linear guide  53  has linear rails  53   a  fixed to the holding body  55 , and a linear slider  53   b  which is fixed with the connecting part  54  and which moves up and down above the linear rails  53   a . Further, the Y axis linear guide  43  has a linear rail  43   a  fixed with the support body  62  and the linear slider  43   b  to horizontally move on the linear rail  43   a . Note that as in the case of the first embodiment  60  of the ZY drive axes, a part which moves integrally with the Z axis movable part  51  will be referred to as a “Z axis movable body”. 
         [0060]    Next, the elevation axis fall prevention unit  80 A according to the second embodiment as one of the characteristic features of the present invention will be described. The elevation axis fall prevention unit  80 A has the stopper  81  fixed to the connecting part  54 , a pull solenoid  84 , fixed to the bottom of the holding body  55  and supplied with power from the main power source, which always pulls a pull bar  84   a , a spring  85  fixed to the bottom of the holding body  55 , and an actuation bar  86  with one end connected to the pull bar  84   a  and the other end connected to the spring  85 . In the present embodiment, the support drive part has the pull solenoid  84 , the spring  85  and the actuation bar  86 . Note that the pull solenoid  84  is fixed to a bottom  55   a  of the holding body  55 , and a supporting point  86   a  of the actuation bar  86  is fixed to the Y axis movable part  52 . 
         [0061]    In the elevation axis fall prevention unit  80 A having the above structure, upon loss of power as shown in  FIG. 7 , the pull bar  84   a  of the pull solenoid  84  becomes free, the pull bar  84   a  is protruded with the spring  85 , to support the stopper  81 , thus fall of the bonding head  35  on the substrate can be prevented. In the present embodiment, another power source is unnecessary. Note that in  FIG. 7 , the Y drive axis  40 A and the support body  62  are omitted. 
         [0062]    According to the above-described second embodiment of the elevation axis fall prevention unit, upon loss of power at the main power source  91 , it is possible to actuate the pull solenoid even without another power source and prevent fall of the bonding head having an elevation axis of a linear motor. 
         [0063]    As a result, also in the second embodiment of the elevation axis fall prevention unit, it is possible to prevent breakage of the bonding head and the substrate. 
         [0064]    In the above-described first and second embodiments, the pusher solenoid  82  and the pull solenoid  84  are arranged below the stopper  81 , however, as shown in  FIG. 8 , they may be fixedly arranged askance in the Z axis drive unit  52  according to the second embodiment or the holding body  55  ( FIG. 8A ), or may be fixedly arranged upward ( FIG. 8B ). In  FIGS. 8A and 8B , a normal status in packaging processing without loss of power is indicated with a broken line, while that upon loss of power, with a solid line. In  FIG. 8A , upon loss of power, a pusher bar  82   a  of the pusher solenoid  82  is projected, to support the stopper  81 . In  FIG. 8B , upon loss of power, the pull bar  84   a  of the pull solenoid  84  is sucked, to support the stopper  81 . Another power source is required in the examples in  FIGS. 8A and 8B . 
         [0065]    Further, the position of the stopper  81  is not limited to the positions shown in  FIGS. 2 and 6 , but may be any position as long as the stopper moves up/down along with the bonding head  35 . The stopper position is similarly set in other embodiments. Further, the solenoid is not limitedly used but an air cylinder may be used as long as necessary response can be ensured. 
         [0066]    Next, an elevation axis fall prevention unit  80 B according to a third embodiment as one of the characteristic feature of the present invention will be described with reference to  FIGS. 9A to 9C .  FIG. 9A  illustrates elevation axis fall prevention unit  80 B according to the third embodiment provided on the ZY drive axis  60 A according to the second embodiment.  FIG. 9B  illustrates a status of the elevation axis fall prevention unit  80 B without loss of power, and  FIG. 9C , a status of the elevation axis fall prevention unit  80 B upon loss of power. Note that in  FIG. 9A , the Y drive axis  40 A and the support body  62  are omitted. 
         [0067]    The elevation axis fall prevention unit  80 B has a hollow case  181  having a ring-shaped hollow part with one end fixed to the Z axis stationary part  52  and with the inner periphery of the other end opened, an incombustible elastic body (e.g. rubber)  182  provided at least in the ring-shaped hollow part, a shape memory alloy  184  provided on the periphery of the elastic body  182 , and a brake rod  185  as a projection part provided on the upper side of the bonding head  35 . Note that as the projection part, a suction nozzle  35   a  provided at the end of the bonding head  35  in place of the brake rod may be used. 
         [0068]    In the shape memory alloy  184 , when power is supplied from the main power source  91  and an electric current flows through the shape memory alloy, a shape to maintain the elastic body  182  away from the brake rod  185  as shown in  FIG. 9B  is memorized. On the other hand, upon loss power, when the electric current does not flow, the radius of the shape memory alloy  184  is reduced as shown in  FIG. 9C . As a result, upon loss of power, the shape memory alloy  184  compresses the elastic body  182 , and the elastic body  182  applies a brake to the brake rod  185 , to prevent fall of the bonding head  35 . In the present embodiment, the other power source  92  is not necessary. Note that when an inverse shape is memorized in the shape memory alloy  184 , the other power source  92  is necessary. 
         [0069]    In the above-described elevation axis fall prevention unit  80 B according to the third embodiment, similar advantages to those in the first and second embodiments can be obtained. 
         [0070]    Next, an elevation axis fall prevention unit  80 C according to a fourth embodiment as one of the characteristic features of the present invention will be described with reference to  FIGS. 10A and 10B .  FIGS. 10A and 10B  illustrate the Z drive axis  50 A according to the second embodiment and the elevation axis fall prevention unit  80 C according to the third embodiment provided on the Z drive axis  50 A.  FIG. 10A  illustrates the ZY drive axes  60 A in the position where the bonding head  35  exists in  FIG. 5 , viewed from an arrow D direction, in a normal status without loss of power.  FIG. 10B  illustrates the ZY drive axes  60 A shown in  FIG. 10A  viewed from an upper direction.  FIG. 11  illustrates a status of the elevation axis fall prevention unit  80 C upon loss of power. 
         [0071]    The elevation axis fall prevention unit  80 C in the fourth embodiment has a spring  186 , an electromagnet  187 , a support drive part with one end fixed to the spring  186  while the other end provided with an actuation plate  188  as an actuation part attracted to the electromagnet  187  and a guide rod  189  to guide up and down movement of the actuation plate  188  along with the Z axis stationary part  52 , and the stopper  81 . 
         [0072]    When power is supplied from the main power source  91  and the electric current flows through the shape memory alloy, the actuation plate  188  is attracted to the electromagnet  187  as shown in  FIG. 10A , thus the status where the spring  186  is compressed is maintained. On the other hand, upon loss of power and the electric current does not flow, the actuation plate  188  is released and the spring  186  is expanded as shown in  FIG. 11 . As a result, the actuation plate  188  supports the connecting part  54 , thus fall of the bonding head  35  can be prevented. 
         [0073]    In the above-described elevation axis fall prevention unit  80 B in the fourth embodiment, similar advantages to those in the first to third embodiments can be obtained. 
         [0074]    Next, an elevation axis fall prevention unit  80 D according to a fifth embodiment as one of the characteristic features of the present invention will be described with reference to  FIGS. 12A and 12B .  FIGS. 12A and 12B  illustrate the elevation axis fall prevention unit  80 D according to the fifth embodiment provided in place of the elevation axis fall prevention unit  80 A according to the second embodiment shown in  FIGS. 6A and 6B , on the ZY drive axes  60 A.  FIG. 12A  illustrates a normal status without loss of power, and  FIG. 12B , a status upon loss of power. 
         [0075]    The elevation axis fall prevention unit  80 D is fixed to the Y axis fixing unit or the support body  62  or a fixing part around these parts in positions E or F shown in  FIG. 5 . The elevation axis fall prevention unit  80 D has two pusher solenoids  82  provided in the positions E and F in which the protrusion part of a push bar  82   a  is prolonged upon loss of power in the elevation axis fall prevention unit  80  according to the first embodiment, an actuation rod  281  as an actuation part with both ends fixed to the end of the two push bars  82   a , and the stopper  81  fixed to the side of the bonding head  35  on the opposite side to the connecting part  54 . In the present embodiment, the support drive part has the two pusher solenoids  82  and the actuation rod  281 . 
         [0076]    As shown in  FIG. 12B , in the elevation axis fall prevention unit  80 D, upon loss of power, the two push bars  82   a  are protruded, to push up the actuation rod  281 , to support the stopper  81 , thus fall of the bonding head  35  can be prevented, as in the case of the elevation axis fall prevention unit  80 . 
         [0077]    As described above, the elevation axis fall prevention unit  80 D according to the fifth embodiment, different from the first to fourth embodiments, is provided not on the Z drive parts  40  and  40 A but on the Y axis fixing part or the support body  62  or a fixing part around these parts. Further, as the actuation of the actuation rod  281 , the methods shown in the second to fourth embodiments are applicable. 
         [0078]    According to the above-described elevation axis fall prevention unit  80 D according to the fifth embodiment, as the elevation axis fall prevention unit is not provided in the Z drive parts  40  and  40 A, the structure of the Z drive part can be simplified. 
         [0079]    Further, according to the above-described elevation axis fall prevention unit  80 D according to the fifth embodiment, fall of the bonding head  35  can be prevented as in the case of the other embodiments. 
         [0080]    Finally, an elevation axis fall prevention unit  80 E according to a sixth embodiment as one of the characteristic features of the present invention will be described. 
         [0081]    In the elevation axis fall prevention unit  80 E according to the sixth embodiment, upon loss of power, a controller  9  controls e.g. the stationary electromagnet  57  shown in  FIG. 2  with the other power source  92 , to move up the bonding head  35  (Z axis movable part  52 ) or maintain that status, to hold the bonding head  35  in a predetermined position. 
         [0082]    According to the sixth embodiment of the elevation axis fall prevention unit, it is possible to prevent fall of the bonding head  35  without any new mechanism other than the other power source  92 . 
         [0083]    In the above description, the bonding head is used as a handling part. Basically, the bonding head is applicable to a handling part requiring a biaxial drive mechanism having an elevation axis. For example, in a die bonder, it is applicable to a needle to apply a die adhesive to a substrate. 
         [0084]    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.