Abstract:
An apparatus  200  for delivering semiconductor components  212  to a substrate  206   a;    206   b;    500   a;    500   b;    500   c  during semiconductor package manufacturing is disclosed. The apparatus  200  comprises a platform  216  and a plurality of delivery modules  202   a,    202   b  affixed to the platform  216.  Each of the plurality of delivery modules  202   a,    202   b  has a support device  204   a;    204   b  for supporting the substrate  206   a;    206   b;    500   a;    500   b;    500   c,  as well as a delivery device  208   a;    208   b  for delivering the semiconductor components  212  to the substrate  206   a;    206   b;    500   a;    500   b;    500   c.  In particular, heights of the support devices  204   a,    204  are mutually levelled for conveying the substrate  206   a;    206   b;    500   a;    500   b;    500   c  between the plurality of delivery modules  202   a,    202   b.

Description:
FIELD OF THIS INVENTION 
       [0001]    This invention relates to an apparatus for delivering semiconductor components to a substrate during semiconductor package manufacturing. The apparatus is particularly, but not exclusively, suitable for delivering semiconductor dice from wafer tables to leadframes during die-bonding. 
       BACKGROUND OF THE INVENTION 
       [0002]    Die-attach machines are commonly used in semiconductor package manufacturing to accurately transfer semiconductor components to semiconductor substrates. For instance, a die bonder has a die-delivery head for transferring semiconductor dice from a wafer table to a leadframe in a pick-and-place operation. However, there is a limitation in the throughput of die-bonding processes—normally quantified in terms of ‘Units per Hour’ (UPH)—attainable by die bonders with a single bond head. 
         [0003]    One way of increasing the UPH of such die bonders is by constructing a system of cascading die bonders.  FIG. 1  shows a system  100  constructed by connecting two die bonders  102 ,  104  together. The system  100  comprises wafer tables  106 ,  108  for placing a wafer containing singulated semiconductor dice  107 , support devices  110 ,  112  for conveying leadframes  109 ,  111  along an X-direction, and die-delivery devices  114 ,  116  having respective die-delivery heads  118 ,  120  for transferring the semiconductor dice  107  from the wafer tables  106 ,  108  to bonding locations of the leadframes  109 ,  111  along a Y-direction orthogonal to the X-direction. A conveying device  122  is further arranged between the two die bonders  102 ,  104  for transferring the leadframes  109 ,  111  from an offload section of the leftmost die bonder  102  to an onload section of the rightmost die bonder  104 . 
         [0004]    If other support devices  110 ,  112  having larger widths are used to support leadframes with corresponding larger leadframe widths, the distance travelled by the die-delivery heads  118 ,  120  from the wafer tables  106 ,  108  to the outermost edges of the leadframes along the Y-direction would be increased. This accordingly reduces the UPH of the system  100 . 
         [0005]    In addition, a large footprint is typically required to construct the system  100  which comprises two separate die bonders  102 ,  104  connected via the intervening conveying device  122 . Thus, construction of the system  100  takes up valuable space in a factory. 
         [0006]    Furthermore, the system  100  of cascading die bonders  102 ,  104  means that it has twice as many devices as that of a single die bonder. Accordingly, the probability of any one of the devices malfunctioning in the system  100  will be higher than that of a single die bonder. As the die bonders  102 ,  104  perform die-bonding in a sequential manner within the system  100 , a malfunction of any one of the die bonders  102 ,  104  invariably causes an operational halt of the entire system  100 , thereby affecting its UPH. 
         [0007]    It is therefore an object of this invention to ameliorate any one of the above limitations of such systems  100  comprising cascading die bonders  102 ,  104 . 
       SUMMARY OF THE INVENTION 
       [0008]    An aspect of this invention relates to an apparatus for delivering semiconductor components to a substrate during semiconductor package manufacturing. The apparatus comprises a platform, and a plurality of delivery modules affixed to the platform. Each of the plurality of delivery modules has a support device for supporting the substrate, and a delivery device for delivering the semiconductor components to the substrate. In particular, heights of the support devices are mutually levelled for conveying the substrate between the plurality of delivery modules. 
         [0009]    The term ‘affixed’ in the context of the description herein means that the plurality of delivery modules are fastened to the platform, wherein some or all of the plurality of delivery modules may be movably fastened to the platform. 
         [0010]    Since the heights of the support devices of the apparatus are mutually levelled, the step of ensuring that the support devices are arranged at a same height may not be necessary when operating embodiments of the claimed apparatus. This advantageously saves valuable time. By contrast, such a step must be taken in the system  100  comprising cascading die bonders  102 ,  104  to ensure that the substrate will be properly conveyed between adjacent die bonders  102 ,  104 . Thus, various steps involving precise measurements of the die bonders  102 ,  104  are required to ensure that the heights of their respective support devices  110 ,  112  are mutually levelled for conveying the leadframes  109 ,  111 . This invariably consumes time and complicates the die-bonding process. 
         [0011]    Some optional features of the apparatus are defined in the dependent claims. 
         [0012]    For example, the plurality of delivery modules may be arranged at opposite sides of the respective support devices along the direction in which the substrate is to be conveyed. In this way, the delivery devices may be configured to deliver the semiconductor components to bonding locations at respective nearer halves of the substrate relative to the delivery devices. These respective nearer halves of the substrate are along the direction in which the substrate is to be conveyed. Since the distance travelled by the delivery devices is shortened, the UPH capacity among embodiments of the claimed apparatus can be advantageously improved. In addition, at least one of the plurality of the delivery modules may be movable in relation to the platform to arrange the respective support devices at a mutual offset along a direction transverse to the direction in which the substrate is to be conveyed. Advantageously, the UPH capacity among embodiments of the claimed apparatus may also be improved when the leadframes having narrower leadframe widths are used. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0013]    Embodiments of the invention will now be described, by way of example only, with reference to the drawings of which: 
           [0014]      FIG. 1  shows a conventional system of cascading die bonders; 
           [0015]      FIG. 2  is an isometric view of a preferred embodiment of the invention having two delivery modules; 
           [0016]      FIG. 3  is a plan view of the preferred embodiment of  FIG. 2 ; 
           [0017]      FIG. 4  is a plan view of a typical leadframe; 
           [0018]      FIG. 5  illustrates a die-bonding operation undertaken by the preferred embodiment as shown in  FIG. 2  and  FIG. 3 ; 
           [0019]      FIG. 6  is an isometric view of a different configuration of the preferred embodiment as shown in  FIG. 2  and  FIG. 3 , in which the delivery modules are arranged at a mutual offset; 
           [0020]      FIG. 7  is a plan view of the preferred embodiment of  FIG. 6 ; and 
           [0021]      FIG. 8  illustrates a die-bonding operation undertaken by the preferred embodiment as shown in  FIG. 6  and  FIG. 7 . 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0022]      FIG. 2  is an isometric view of a die bonder  200 , which comprises two die-delivery modules  202   a ,  202   b  having: i) support devices  204   a,    204   b  for conveying substrates such as leadframes  206   a ,  206   b  in an X-direction; ii) die-delivery devices  208   a,    208   b  arranged in relation to the respective support devices  204   a,    204   b;  iii) wafer tables  210   a,    210   b  for placing semiconductor dice  212 ; and iv) pick-and-bond optical systems (not shown) to ensure accuracy of the pick-and-place operations. 
         [0023]    Specifically, the die-delivery devices  208   a,    208   b  includes die-delivery heads  214   a,    214   b  configured to pick up the semiconductor dice  212  from the respective wafer tables  210   a,    210   b  and transfer them—in a Y-direction orthogonal to the X-direction—to bonding locations of the respective leadframes  206   a,    206   b.  The die-delivery heads  214   a,    214   b  are arranged at opposite sides of the support devices  204   a,    204   b  along the X-direction to improve the UPH of the die bonder  200  (more details are set out below). 
         [0024]    In addition, the die bonder  200  includes a platform  216  to which the die-delivery devices  202   a ,  202   b  are affixed. In particular, the heights of the support devices  204   a,    204   b  are mutually levelled when the die-delivery modules  202   a,    202   b  are affixed to the platform  216  to ensure that the leadframes  206   a,    206   b  are conveyed between the die-delivery modules  202   a,    202   b  during die-bonding.  FIG. 2  shows the platform  216  being an integral one-piece level platform with various tracks  218   a,    218   b  along which the die-delivery devices  208   a,    208   b  are adjustably movable. The arrangement of the tracks  218   a,    218   b  as shown in  FIG. 2  is solely for the sake of explanation. It should be appreciated that these tracks  218   a,    218   b  are arranged at the undersides of the die-delivery modules  202   a,    202   b  and would thus be hidden from view. 
         [0025]    The die bonder  200  further includes a motion device for adjusting the relative arrangement of the delivery modules  202   a,    202   b.  One example of the motion device is shown in  FIG. 2  which—again solely for the sake of explanation—comprises rollers  220   a,    220   b  attached to the die-delivery modules  202   a,    202   b  and tracks  218   a,    218   b  arranged on the platform  216 . Specifically, the rollers  220   a,    220   b  are mounted on the respective tracks  218   a,    218   b  of the platform  216  to adjust the relative arrangement of the delivery modules  202   a,    202   b.  It should be appreciated that the rollers  220   a,    220   b  are arranged at the undersides of the die-delivery modules  202   a,    202   b,  and would thus be hidden from view. As the tracks  218   a,    218   b  are arranged along the X and Y directions respectively, the die-delivery modules  202   a,    202   b  can accordingly be configured to move in the corresponding X and Y directions. 
         [0026]    Adjustment in the X direction may be necessary for long leadframes that are in reel form which traverse from one die-delivery device  208   a  to the other die-delivery device  208   b.  Such adjustment ensures that the distance between bonding positions in the respective die-delivery devices  208   a ,  208   b  is equal to a multiple of a column pitch between adjacent bonding pads on the leadframe. 
         [0027]    The die-delivery module  202   a  is adjustably movable along the X-direction within along a wide range of distances, whereas the die-delivery module  202   b  is adjustably movable along the Y-direction also within a wide range of distances, in order to add greater versatility in adapting the apparatus to different machine designs. 
         [0028]      FIG. 3  is a plan view of the die bonder  200 . Preferably, the die bonder  200  houses two delivery modules  202   a,    202   b  within an integral chassis. In contrast with the conventional system  101  which requires two separate die bonders  102 ,  104  and the intervening conveying device  122 , the die bonder  200  thus requires a smaller footprint. 
         [0029]    Furthermore, each of the die bonders  102 ,  104  of the conventional system  101  includes a separate indexing unit for conveying the respective support devices  110 ,  112  by a column pitch of the leadframes  109 ,  111  whenever corresponding columns of bonding locations of the leadframes  109 ,  111  have been occupied by the semiconductor dice  107 . By contrast, both the die-delivery modules  202   a,    202   b  of the die bonder  200  may use a single indexing unit for conveying both the support devices  204   a,    204   b  by a column pitch of the leadframes  206   a,    206   b  during bonding of respective columns of bonding locations. Since the die bonder  200  requires fewer devices than the conventional system  100 , the likelihood of any one device of the die bonder  200  malfunctioning is thus lower compared with the conventional system  100 . This advantageously translates to a higher UPH capacity of the die bonder  200  throughout its useful life than the conventional system  100 . 
         [0030]      FIG. 4  is a plan view of the leadframe  206   a  having various bonding locations  400  to form a column of bonding locations  400  along the leadframe width  402 . Various columns of bonding locations  400  are arranged along the leadframe length  404 , and the distance between adjacent columns is defined as the ‘column pitch’  406  of the leadframe. 
         [0031]    An operation of the die bonder  200  of  FIG. 2  and  FIG. 3  will now be explained with reference to  FIG. 5 . Each of the die-delivery heads  214   a,    214   b  is responsible for transferring the semiconductor dice  212  from the respective wafer tables  210   a,    210   b  to bonding locations of the leadframes  206   a,    206   b  at the respective lower halves of the leadframes  206   a,    206   b  which are nearer to the corresponding die-delivery heads  214   a,    214   b.  With reference to  FIG. 5 , since the die-delivery head  214   a  is located next to a lower portion of the support device  204   a,  it is thus configured to transfer the semiconductor dice  212  from the wafer table  210   a  to the bonding locations at the lower half portion of the leadframe  206   a.  As the die-delivery head  214   b  is located next to an upper portion of the support device  204   b,  it is thus configured to transfer the semiconductor dice  212  from the wafer table  210   b  to the bonding locations at the upper half portion of the leadframe  206   b.    
         [0032]    By configuring the die-delivery heads  214   a,    214   b  to transfer the semiconductor dice to the bonding locations at the respective nearer halves of the leadframes  206   a,    206   b  relative to the corresponding die-delivery heads  214   a,    214   b,  each die-delivery head  214   a,    215   b  can avoid travelling the distance from the wafer tables  210   a,    210   b  to the bonding locations at the furthermost portions of the respective leadframes  206   a,    206   b.  Thus, the distance travelled by the die-delivery heads  214   a,    214   b  can be shortened. This advantageously improves the UPH of the die bonder  200 . 
         [0033]      FIG. 6  is an isometric view of a different configuration of the die bonder  200 . In this configuration, the die-delivery module  202   b  has been shifted relative to the other die-delivery module  202   a  in the Y-direction—which is orthogonal to the leadframe-conveying X-direction—such that the respective support devices  204   a,    204   b  are arranged at a mutual offset in the Y-direction. Specifically, the die-delivery module  202   b  is shifted along with the track  218   b  in the Y-direction until the support devices  204   a,    204   b  define an overlapping path in the X-direction with a path width corresponding to the width of the narrower leadframes  500   a,    500   b,    500   c  being processed. 
         [0034]      FIG. 7  is a plan view of the configuration of the die bonder  200  shown in  FIG. 6 , showing the mutual offset  700  between the support devices  204   a,    204   b  along the Y-direction. 
         [0035]    An operation of the configuration of the die bonder  200  shown in  FIG. 6  and  FIG. 7  will now be explained with reference to  FIG. 8 . 
         [0036]    Like the die bonder operation as explained with reference to  FIG. 5 , each of the die-delivery heads  214   a,    214   b  is responsible for transferring the semiconductor dice  212  from the respective wafer tables  210   a,    210   b  to bonding locations at the respective nearer halves of the leadframes  500   b ,  500   c  relative to the die-delivery heads  214   a,    214   b,  as the support devices  204   a,    205   b  move in the X-direction during die-bonding. As the die-delivery head  214   a  is located next to the lower portion of the support device  204   a,  it is thus configured to transfer the semiconductor dice  212  from the wafer table  210   a  to the bonding locations at the lower half portion of the leadframe  500   b.  As for the die-delivery head  214   b,  since it is located next to the upper portion of the support device  204   b,  it is thus configured to transfer the semiconductor dice  212  from the wafer table  210   b  to the bonding locations at the upper half portion of the leadframe  500   b.    
         [0037]    By configuring the die-delivery heads  214   a,    214   b  to transfer the semiconductor dice to the bonding locations at the nearer halves of the leadframes  500   b,    500   c  relative to the die-delivery heads  214   a ,  214   b,  the die-delivery heads  214   a,    214   b  avoid travelling a longer distance from the wafer tables  210   a,    210   b  to the bonding locations at the respective furthermost portions of the leadframes  500   a ,  500   b.    
         [0038]    Without the ability to adjustably move the die-delivery module  202   b  such that the support devices  204   a,    204   b  define an overlapping path with a path width corresponding to the width of the narrower leadframes  500   a,    500   b,    500   c  to be processed, the die-delivery head  214   b  will be located at position E as shown in  FIG. 7 . Consequently, the die-delivery head  214   b  has to move by an additional distance  800 —corresponding to the mutual offset  700  between the support devices  204   a ,  204   b  in the Y-direction—for every pick-and-place operation of the die-bonder  202 . 
         [0039]    By adjusting the relative arrangement of the respective support devices  204   a,    204   b,  the distance travelled by the die-delivery heads  214   a,    214   b  can be shortened by the offset distance  700  for every pick-and-place step performed by the die bonder  200 . Thus, it can be seen that the ability to adjust the relative arrangement of the die-delivery modules  202   a,    202   b  to define the offset  700  between their support devices  204   a,    205   b  means that the die-bonder  200  may be adapted for use with leadframes with narrower leadframe widths to improve the UPH capacity of the die bonder  200 . 
         [0040]    Of course, it should be appreciated that the overlapping path as defined by the support devices  204   a,    204   b  may also have a width larger than that of the narrower leadframes  500   a,    500   b,    500   c.    
         [0041]    It should further be appreciated that other variations of the preferred embodiment may be possible without departing from the scope and spirit of the invention. For instance, instead of the die-delivery module  202   a  being movably adjustable along the X-direction, tracks extending in the orthogonal Y-direction may instead be provided on the platform  216  so that the die-delivery module  202   a  may also be adjustably movable along the Y-direction to arrange the respective support devices  204   a ,  204   b  at a mutual offset in the Y-direction. Also, while the preferred embodiment of this invention relates to a die bonder for transferring semiconductor dice to a leadframe, embodiments of the invention may also be used to mount electronic components to a printed circuit board (PCB) in surface mount technology applications.