Abstract:
A method and system for sorting IC-components into pre-definable classes of criteria simultaneously remove a plurality of the IC-components from receiving portions of a tray using a plurality of gripping devices. Each of the gripping devices having an access area that is separate from access areas associated with the other gripping devices. The tray is moved in steps past the gripping devices. Each of the gripping devices is controlled to remove from the receiving portions of the tray only the IC-components belonging to one class of criteria assigned to the access area of the respective gripping device.

Description:
TECHNICAL FIELD 
     The invention relates to a method for the sorting of IC-components which during manufacture in the back-end stage are sorted corresponding to pre-definable classes of criteria and particularly are sorted into different classes corresponding to their test results. 
     BACKGROUND 
     In the production of IC-components, the components are subjected to various tests in the back-end stage. Subsequently, the IC-components are sorted into different classes corresponding to their test results. The sorting process is performed with the aid of a plurality of gripping means which access the individual receiving portions of the trays on which the IC-components are transported in the back-end stage. Each gripping means can access each IC-component to pick it up, classify it corresponding to its test results and to deposit it. This process is relatively time-consuming. 
     Further, testing and sorting devices are known from DE 35 39 968 A1 and DE 36 38 430 A1 wherein the components are sequentially tested and corresponding to their test results are supplied successively to one of a plurality of magazines. 
     SUMMARY 
     It is the object of the invention to provide a sorting method for the sorting of IC-components in the back-end stage which is highly effective and by which all of the IC-components of a tray are sorted into different classes in the shortest time possible. 
     For solving the above object, there is proposed in accordance with the invention a method for the sorting of IC-components in the back-end stage corresponding to pre-definable classes of criteria, wherein 
     the IC-components are simultaneously removed from receiving portions of a tray by a plurality of gripping means, 
     each gripping means has a pre-definable access area for the removal of IC-components from receiving portions of the tray, with the access areas of all gripping means being free of mutual overlapping, 
     the tray is moved in steps past the gripping means, and 
     each gripping means removes only the IC-components belonging to one class of criteria from the receiving portions of the tray belonging to the access area of the respective gripping means. 
     In the method according to the invention, use is made of a plurality of gripping means whose number is at least equal to the number of classes into which the IC-components are to be sorted. Each gripping means has a specific access area assigned thereto within which the gripping means can travel to remove IC-components from the receiving portions of the trays. All of the access areas are free of any overlapping with each other. The tray is moved past the gripping means so that each receiving portion of the tray will be moved through the access areas of all of the gripping means. Each gripping means will remove, from those receiving portions of the tray which during the stepwise advance of the tray are presently located in the access area assigned to the gripping means, only those IC-components which on the basis of the respective pre-defined criteria, e.g. on the basis of the test results, are to be assigned to a specific class. 
     Thus, in the method of the invention, a sequential stepwise transport of the trays past the gripping means is performed, with the gripping means accessing the IC-components in parallel. In this manner, the effectiveness of the sorting mechanism and of the sorting method, respectively, is decisively increased to the effect that the sorting method is performed continuously, as it were, instead of the previously known batch-like operation. 
     For a case when a gripping means has to access a larger-than-average number of IC-components presently located in its access area because all of these 
     IC-components belong to the self-same class, it is of advantage to provide a plurality of gripping means per class. Due to the stepwise transport of the tray, this plurality of gripping means per class is serviced sequentially. That gripping means which is first serviced will remove a maximum number of IC-components. The time period required therefore is adapted to the dwell time in the rest condition and thus to the cycle rate of the stepwise transport of the tray. Should not all of the IC-components of the class assigned to the first gripping means have been removed within this time period, the next IC-components will be removed by the second gripping means assigned to this class. Also this gripping means will remove a maximum number of IC-components. In as far as the case is imaginable that both gripping means together cannot remove all of the IC-components respectively arranged in their access areas, further gripping means are provided which then can remove the rest of the IC-components of this class from the receiving portions as soon as these are within the access areas of the further gripping means. 
     Normally, for the transport of IC-components in the back-end production region, use is made of trays comprising a plurality of the deepened receiving portions which are again arranged in a regular manner and particularly in a matrix form, e.g. in mutually orthogonal columns and rows. In such trays, it is suitable to assign to each gripping means one access area which comprises a column (or alternatively a row) of receiving portions of the tray. In this case, all of the gripping means are arranged successively next to each other in the moving direction of the tray. The advance movement of the trays themselves is performed suitably at right angles to the extension of the columns (or alternatively rows) of receiving portions. 
     An embodiment of the invention will be explained in greater detail hereunder with reference to the Figures. 
    
    
     BRIEF DECEPTION OF THE DRAWINGS 
     FIG. 1 is a plan view of a tray comprising a plurality of receiving portions for IC-components arranged in a matrix form, and 
     FIGS. 2 to  4  are graphic representations of successive phases during the stepwise advance movement of the tray according to FIG.  1  and during removal of individual IC-components by different gripping means corresponding to the classes to which the IC-components have been assigned on the basis of test results. 
    
    
     DETAILED DESCRIPTION 
     FIG. 1 shows a plan view of a plastic tray as used in the back-end stage in the manufacture of IC-components for transporting the latter. The tray  10  comprises a plurality of deepened receiving portions  12  positioned in a regular manner. These deepened receiving portions  12  are arranged in mutually orthogonal columns  14  and rows  16  on tray  10 . The deepened receiving portions  12  contain IC-components  18  which have been subjected to a plurality of tests of various types. The individual test results are stored in a memory while allocated to the receiving positions of the IC-components  18  within tray  10 . On the basis of the results of the tests, the IC-components  18  can be assigned to different classes and groups, respectively. Also this class or group assignment is stored in the memory for each IC-component  18 , notably with regard to its receiving position within tray  10 . Subsequent to the tests, it is stored in the memory, for instance, that the IC-component  18  which is arranged e.g. in the first column  14  from the right in the representation of FIG.  1  and in the fifth row  16  from above in the representation of FIG. 1, has to be assigned to class  3 . 
     For sorting the IC-components  18  of tray  10 , the latter is moved according to FIG. 2 in the direction of arrow  20  past a plurality of suction gripping means  22  arranged in series in the transport direction  20  of tray  10 . Each suction gripping means  22  comprises a suction head  24  arranged for advance and return movement over tray  10  performed rectangularly to the transport direction of tray  10 , which is indicated by the double-pointed arrows  26 . In other words, each suction head  24  moves within an access area  28  arranged in the extension of the column  14  of the deepened receiving portions  12  of tray  10 . The access areas  28  of the suction gripping means  22  are arranged laterally to each other and behind each other, respectively, in the transport direction  20  of tray  10 . 
     The movement of the tray  10  in the transport direction  20  is carried out in steps, with the tray  10  being moved in a clocked manner each time by the width of one column  14  and then is brought to a standstill for a predetermined period of time. In this manner, the tray  10  is sequentially moved past all of the suction gripping means  22 . 
     FIG. 2 illustrates the situation in which the tray  10  has been advanced so far that its leading column  14  of receiving portions  12  in the transport direction  20  is located within the access area  28  of the first suction head  24 . The encircled arabic numbers of the IC-components  18  and the suction heads  24  of FIGS. 2 to  4  indicate to which of a total of eight classes a IC-component  18  belongs or which suction head  24  removes IC-components  18  of which class from tray  10 . In FIG. 2, after the stepwise advance transport and during the time of standstill of tray  10 , the suction head  24  assigned to class  1  accesses the IC-components  18  of the first column  14  in order to remove the two IC-components  18  designated by class  1  in the rows  2  and  5  (counted from above in the representation of FIG.  2 ). Suction head  24  sequentially removes these two IC-components  18  and deposits them at a transfer site  30  assigned to the suction gripping means  22 , from where the sorted-out IC-components  18  are transported further on or are placed in a magazine. 
     After the two IC-components  18  assigned to class  1  have been removed from the first column  14  and the time of time of standstill of tray  10  has lapsed, tray  10  is advanced by the width of one column  14  in the transport direction  20  and then is stopped again. Thereafter, the situation will be again that according to FIG. 3; now, the leading two columns  14  of receiving portions  12  of tray  10  as viewed in the transport direction  20  are located within the access areas  28  of the first two suction gripping means  22  provided for sorting out IC-components  18  of classes  1  and  2 . In the situation shown in FIG. 3, the two suction heads  24  for classes  1  and  2  will access the second and first columns of deepened receiving portions  12  in the transport direction. In the process, the suction head  24  assigned to class  2  will remove the IC-components  18  in the uppermost and in the last-but one row of the first column, while the suction head  24  assigned to class  1  will remove, from the second column, those IC-components  18  which are arranged in the third, fifth and eight row as counted from above. After lapse of the standstill period, tray  10  is again moved by the width of one column, so that now the first three columns  14  of tray  10  are arranged within the access areas  28  of the suction gripping means  22  assigned to classes  1 ,  2  and  3 . The situation prevailing subsequent to that according to FIG. 3 is illustrated in FIG.  4 . The removing process in the situation according to FIG. 4 is performed in parallel by means of three suction heads  24  which access the IC-components  18  located in the deepened receiving portions  12  of the first three columns  14  in as far as these components belong to the classes allocated to the respective suction heads  22 . Thus, for instance, the suction head  24  assigned to sort out IC-components of class  3  will access the IC-component in the third row from above of the first column  14  of tray  10 . The suction head  24  assigned to sort out IC-components  18  of class  2  will access the IC-components in the uppermost row and in the last-but-one row of the second column of tray  10  in the transport direction, while the suction head  24  assigned to class  1  will remove, from the third column  14  of deepened receiving portions  12  in the transport direction, the third IC-component  18  arranged in the deepened receiving portion  12  of the uppermost row. The controlling of the suction head movements for positioning the suction heads  24  in their traveling directions  26  above the respective IC-components  18  to be gripped will follow the data stored in the memory on the classification of the IC-components  18 . Once the tray  10  has been completely moved past the suction gripping means  22  assigned to the eight classes, all of the IC-components  18  of tray  10  will have been removed and stored, while sorted corresponding to their classes, in magazines or the like storage means. 
     In the embodiment described herein and illustrated in the Figures, respectively one suction gripping means  22  is provided for each class to be sorted out. As long as the relation between the number of deepened receiving portions  12  located simultaneously in an access area  28  of a suction gripping means  22  and the number of classes is not considerably larger than  1 , one suction gripping means  22  per class will be sufficient. If, however, the number of possible classes of IC-components  18  is considerably smaller than the number of deepened receiving portions  12  located simultaneously in an access area  28  of a suction gripping means  22 , it is to be assumed that each access area  28  of the suction gripping means  22  contains a plurality of IC-components  18  to be sorted out. The sequential removal of a plurality of IC-components  18  per access area  28  requires a certain minimum time period. To be nonetheless able to work with relatively small cycle rates, i.e. with short standstill periods of the tray  10 , it is recommended that the removal of identically classified IC-components  18  of a column  14  be distributed over two or more clock cycles. Thus, for instance, two suction heads  24  adjoining each other in the transport direction  20  of tray  10  may be provided for the removal of IC-components  18  of the same class. Since the number of IC-components  18  of this class per column is known, it can be defined before-hand how many and which ones of the identically classified IC-components  18  of a column  14  shall be removed by the two or more suction heads  24  assigned to this class. In this manner, the sorting process can be performed with optimally low time requirements.