Abstract:
A method for inspecting and sorting a plurality of IC units comprising the steps of: delivering a frame containing said IC units to a unit picking station; conducting a first inspection of said units during the delivering step and recording the subsequent result; removing said units from the frame, and moving said units from the unit picking station to a flipping station; conducting a second inspection of said units during the moving step and recording the subsequent result; flipping said units to expose an opposed face said units; conducting a third inspection of said opposed face and recording the subsequent result, then; sorting said units into categories based on the recorded results from the first, second and third inspecting steps.

Description:
PRIORITY APPLICATIONS 
     This application is a National Phase Entry of and claims priority from PCT/SG2010/000447, title “METHOD AND APPARATUS FOR IMPROVED SORTING OF DICED SUBSTRATES”, filed on Nov. 30, 2010, which claims priority to Singapore application 200908025-0, filed on Dec. 1, 2009. The above are herein incorporated by reference. 
     FIELD OF THE INVENTION 
     The invention relates to equipment for the handling of integrated circuits and in particular, integrated circuits having been singulated from a substrate. 
     BACKGROUND OF THE INVENTION 
     The economics involved in the processing of integrated circuit units are influenced by the rate of units processed, measured in units per hour (UPH). 
     This rate includes those units not meet specific quality criteria, or units displaced during the processing cycle. 
     To ensure a batch of units meet this criteria it is necessary to subject batches of IC units to inspection prior to packing or end use. 
     SUMMARY OF THE INVENTION 
     In a first aspect, the invention provides a method for inspecting and sorting a plurality of IC units comprising the steps of: delivering a frame containing said IC units to a unit picking station; conducting a first inspection of said units during the delivering step and recording the subsequent result; removing said units from the frame, and moving said units from the unit picking station to a flipping station; conducting a second inspection of said units during the moving step and recording the subsequent result; flipping said units to expose an opposed face said units; conducting a third inspection of said opposed face and recording the subsequent result, then; sorting said units into categories based on the recorded results from the first, second and third inspecting steps. 
     In a second aspect, the invention provides a system for inspecting and sorting a plurality of IC units comprising: a conveyor for delivering a frame containing said IC units to a unit picking station; a first inspection station contiguous with said conveyor, and arranged to inspect said units; said unit picking station including an ejector positioned to selectively lift one or more units out of said frame, and a unit picker assembly for engaging said one or more units on said ejector; said unit picker assembly further arranged to move the one or more ejected units from the unit picking station to a flipping station; a second inspection station contiguous with said unit picker assembly, and arranged to inspect said ejected units; said flipping station arranged to receive and flip the ejected units to expose an opposed face said units; a third inspection station contiguous with said flipping station, and arranged to inspect said flipped units, and; a sorting station for receiving said units and arranged to place said units into designated bins based on results from the first, second and third inspection stations. 
     The present invention is directed to providing a system and method that is capable of inspecting and sorting units in batch form. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
       It will be convenient to further describe the present invention with respect to the accompanying drawings that illustrate possible arrangements of the invention. Other arrangements of the invention are possible and consequently, the particularity of the accompanying drawings is not to be understood as superseding the generality of the preceding description of the invention. 
         FIG. 1  is a plan view of an IC sorting system according to one embodiment of the present invention. 
         FIGS. 2A to 2D  are various views of a loading station according to one embodiment of the present invention. 
         FIGS. 3A to 3C  are various views of a receiving station according to one embodiment of the present invention. 
         FIGS. 4A to 4C  are various views of a conveyor according to one embodiment of the present invention. 
         FIGS. 5A to 5C  are various views of an ejector assembly according to one embodiment of the present invention. 
         FIGS. 6A to 6E  are various views of an inspection system according to one embodiment of the present invention. 
         FIGS. 7A to 7C  are various views of a flipper according to one embodiment of the present invention. 
         FIGS. 8A to 8C  are various views of an unloading system according to one embodiment of the present invention. 
         FIGS. 9A to 9D  are sequential views of a cartridge bin being loaded according to one embodiment of the present invention. 
         FIGS. 10A to 10C  are various views of a loading bin system according to one embodiment of the present invention. 
         FIGS. 11A to 11C  are various views of a tube offloader according to one embodiment of the present invention. 
         FIGS. 12A to 12C  are various views of a ring disposal system according to one embodiment of the present invention. 
         FIGS. 13A to 13C  are various views of a tube racking system according to one embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  shows a plan view of the IC sorting system  5  according to one embodiment of the present invention. Here a loading station as shown in  FIGS. 2A to 2D  includes a lift  11  lifting two platforms  10 ,  13  having cassettes  12 ,  14  of frames for delivery to the sorting system. The individual frames are loaded into the cassettes prior to placement on the platforms  10 ,  13 . The platforms are movable vertical through a lift  11 , so that the first platform  10  can empty the corresponding cassette  12 , before moving the next platform  13  upwards, as shown in  FIG. 2D , to maintain feeding frames into the device. 
     As the first cassette empties, the next moved into place and the first can be slid outwards, as shown in  FIG. 2C  to replace the empty cassette with a new one. Thus, the supply of cassettes is maintained, so long as the cassettes are replaced. 
     The process commences with a frame taken from the available cassette  12 ,  14  engaged by a gripper  15 . The gripper  15  pulls the frame from the cassette and places onto two laterally projecting ledges within a receiving station, as shown in  FIGS. 3A to 3C . The ledges are movable in the lateral direction so as to accommodate the placement of the frame. Thus they retract as the frame is delivered and project into the space provide so as to support the frame in place. 
     A frame engagement assembly, such as a frame picker  25 , then lowers to engage the frame by extending a first vertically oriented actuator  22 . The ledges are then retracted again, and the frame picker  25  is lowered further to a carriage  28 , by the first and a second vertically oriented actuator  24 , mounted in series with the first  22 . 
     As shown in  FIGS. 4A to 4C , the carriage  28  receives the frame which delivers the frame from the receiving station  51  to a unit picking station  54  along a conveyor  52 . In this case, the conveyor  52  is a worm drive operated by a motor to move the carriage into place. At a point along the delivery path the frame undergoes a first inspection from a first vision device  40 . The purpose of the first vision device  40  is to identify and record the type of unit being processed and the alignment of the singulated units. The camera  40  is movable along a rail  30  which, together with the orthogonal movement of the conveyor  52  allows each unit to be inspected whilst located in the carriage  28 . 
     Following inspection the carriage continues on to the unit picking station for the removal of units from the frame. Within the unit picking station is an ejector  45  as shown in  FIGS. 5A to 5C  for individually engaging and lifting individual IC units from the frame to be engaged and removed by a picker  60 . The ejector  45  is located beneath the frame and is movable along a rail  55 . The frame is further rotatable on a turntable  53 , and together with linear movement of the ejector  45  along the ejector rail  55  allows the ejector  45  to access each unit within the frame. The turntable  53  rotates for orientation and alignment. The turntable  53  is movable in the Y-direction and the ejector  45  is movable in the X-direction along the rail  55 , so that the ejector  45  can access each unit within the frame. 
     As shown in  FIGS. 6A to 6D , the picker  60  is movable along a rail  65  to transport an array of units from the frame to a flipper  95 . The picker, in the embodiment engages 10 units at one time, with the flipper accommodating 10 units. It will be clear that any number of units may also be accommodated in alternative embodiments. 
     The type of picker  60  used in the embodiment is one having reciprocating probes arranged in pairs such that the first of each pair engage five units, then retract to allow the second of each pair to engage the final five units. It will be appreciated that different types of picker may be suitable, and that the type described here is merely one of such suitable types. 
     The picker  60  moves along the rail  65  so as to deposit the units on the flipper  95  and in so doing passes the second inspection station  70  having vision to collect data on the units transported by the picker  60 . In particular the vision  70  is placed beneath the rail  65  so that the vision images the underside of the units which in this case provides a check of the pad of each unit for later determination for sorting. The flipper then inverts. 
       FIGS. 7A to 7C  show the flipper  95  and idle block  80  which are mounted upon a worm gear so as to bring the idle block  80  beneath the flipper  95  to receive the IC units on flipping so as to expose the opposed face of the units. The idle block  80  then returns to its original position whereupon the units residing on the idle block are engaged by a picker  90  for eventual placement in the respective bin. 
       FIGS. 8A to 8C  show the arrangement of the picker  90  and the idle block  80 . It further shows a third inspection station  75  having vision to check fiduciary marks. In a further embodiment, this inspection station may be a 2.5D inspection, having an array of mirrors arranged in a rectangular arrangement about the camera  75 . The third inspection station  75  may be arranged such that the picker moves to the extreme end of the rail  85  and extends the unit to be inspected into the mirror array. Here, not only can the camera have a view of the underside of the unit to check fiduciary marks but also have a side vision due to the array of mirrors to check among other things, any bleeding of leads between cells which may short circuit the integrated circuit unit. Thus the four way mirror array allows a view to check horizontally and thus rather than a three dimensional inspection is known as a 2.5D inspection. 
     The picker  90  then moves towards the unloading area whereby the picker is arranged to deposit the units according to the results recorded at the previous inspection stations. For instance, the units may be placed in the good bin  100 , rework bin  105 , reject bin  110  or to a tube offloader  130 . The results recorded by each inspection station may be stored on a database accessible for the purposes of sorting said units according to said results. 
     With respect to the good bin  100  and rework bin  105 ,  FIGS. 9A to 9D  show a sequential process for the good bin  100 . It will be appreciated that the process shown in  FIG. 9A to 9D  is equally applicable to the rework bin  105 , both of which may be generically called housings. 
     Here, a stack of empty cartridges  101  are vertically disposed on a vertical lift  108  ready to be placed upon the receiving platform  116 . With reference to the loading arrangement of the bins shown in  FIGS. 10A ,  10 B and  10 C, the position of the loading platform  116  is shown in  FIG. 9A  is at the same level as the carriage  111  used to receive the integrated circuit units from the picker  90 . 
     After receiving a topmost empty cartridge from the good bin  100 , the carriage  111  travels along a rail which moves along an orthogonal axis to the rail  85  of the picker  90 . The movement of the picker  90  along the rail  85  together with the movement of the carriage  111  along its respective rail permits access to place the integrated circuit units in a suitable array within a cartridge placed on the carriage  111 . On filling the cartridge within the carriage  111 , it is returned to the bin  100  and specifically onto a second platform  104 . The platforms  104  and  116  then move upwards to place the filled cartridge into the existing stack of filled cartridges  102  in the removable bin  103  as shown in  FIG. 9B . 
       FIG. 9C  shows the platform  105  returning to the bin of empty cartridges  101  which is moved upwards by lift  108  to place an empty cartridge onto the platform  116 , and so be the topmost empty cartridge to commence the process again. 
     A gripper then grips the topmost empty cartridge and places it on the carriage  111  to receive the new batch of IC units which will again be placed in the upper platform  104  for eventual placement within the removal bin  103 . 
     Returning to  FIGS. 10A to 10C , it can be seen that the empty cartridges are placed within a bin  114  which slides outwards for easy loading of the bin  114 . 
     An alternative unloading option is the tube offloader  131  as shown in  FIGS. 11A to 11C . Here, a shuttle  122  receives the integrated circuit units from the picker  90 . The shuttle  122  has a central groove into which the units are placed which is then subject to a pusher  120  having a probe that corresponds with the groove. When the shuttle  122  is full, the probe moves along the groove to push the units into an awaiting tube. On filling the tube, the tube is pushed into the racking system  130  shown in  FIGS. 13A to 13C , ready for transportation. 
     It will be noted that the shuttle  122  is aligned to place the units into the tube and so is positioned such that the groove is co-linear with the tube as seen in  FIG. 1 . For convenience in an alternative embodiment, the shuttle may be rotatable so as to receive the integrated circuit units from the picker  90  parallel to the rail  85  upon which the picker  90  moves. Thus in this alternative embodiment, the picker can deposit the units as a group as in this alternative embodiment, the groove and line of units will be co-linear. In the embodiment shown in  FIG. 11A to 11C , because the groove is orthogonal to the rail  85 , the units must be placed individually. Whilst this is convenient for the tube offloader and reduces the cost of infrastructure, there is advantage through speed and convenience to have the shuttle rotatable from a position where the groove is parallel to the rail  85  to a position where the groove is co-linear with the tube into which the IC units will be placed. 
     Referring back to  FIG. 1  and the unit picking station, in a further embodiment, following the removal of the units from the frame, it is still necessary to remove the frame from the system. In one embodiment, the frame may be returned on the carriage  28  for removal by an operator. However, to prevent a bottleneck of empty frames in one direction and full frames in the other,  FIGS. 12A to 12C  show an alternative embodiment where the frame is removed from the unit picking station directly. Here, a further frame engagement assembly, such as frame picker  41 , is mounted to a rotor  42  for rotating the frame picker  41 . In operation, the frame picker  41  engages an empty frame  39  after all the units have been removed. It lifts the frame and rotates away from the unit picking station to a frame bin  46  whereby the frame is released and dropped into the bin. When a supply of empty frames  44  reaches a certain number, it can be removed more efficiently by an operator ready for recycling.