Patent Publication Number: US-2006006095-A1

Title: Universal storage tray for electronic components

Description:
BACKGROUND OF THE INVENTION  
      A number of different trays exist for storing, processing, and transporting components. Since electronic components have various sensitive and delicate features, they must be handled with extreme care. Traditionally, trays for storing electronic components have had stationary side walls.  FIG. 1  illustrates a bottom view of a conventional tray  10 . Tray  10  has stationary sidewalls  12 , and can only be used for holding segments of uniform length. Currently different segment lengths are processed by using different frames for each type of length. The use of different trays is inefficient since typically both segment strips undergo similar manufacturing processes.  
      Accordingly, there is a need for an adjustable tray and method designed to enhance the efficiency of processing electronic components of different channel lengths.  
     SUMMARY OF THE INVENTION  
      The present invention concerns a universal storage tray for automation handling and transporting electronic components. In particular, the tray is an adjustable tray that can receive wafer segments of varying dimensions.  
      In one embodiment the storage trays comprise a tray frame having opposing end walls; and a removable sidewall, The slots from the removable sidewall and an opposing sidewall together form channels for receiving wafer segments. The removable sidewall has terminal ends that engage to a portion of the tray frame, in particular to the end walls of the frame.  
      In a second embodiment, the storage trays comprise end walls integral with a frame, each having a groove; and a stationary sidewall. This embodiment includes an adjustable sidewall that can be moved along the grooves to a predetermined position relative to the stationary sidewall to form a channel for receiving a wafer segment. The resulting channel is configured to have a longitudinal dimension greater than a longitudinal dimension of said wafer segment.  
      Another aspect of the invention comprises securing the contents of the storage tray with a hollow cover. The hollow cover can be either solid or fitted with rectangular gaps. In either case, the hollow cover is preferably fabricated from a clear material that allows the contents of the tray to be easily viewed.  
      Yet another aspect of the invention comprises a method of storing a wafer segment. In one embodiment the method comprises determining the length of the wafer segment; selecting a plurality of regions that cause a channel to be formed having a first channel length corresponding substantially to the desired wafer segment; positioning a removable sidewall into the selected regions to form the channel of said first channel length; and inserting the wafer segment into the channel.  
      The advantages provided by the present invention include a universal storage tray that can be used to process, handle, or transport electronic components in strip format.  
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       FIG. 1  is a perspective view of a prior art tray used for processing electronic components.  
       FIG. 2A  is a perspective view of an embodiment of an adjustable tray having recesses in opposing end walls for receiving a removable sidewall.  
       FIG. 2B  illustrates one embodiment of an adjustable tray in accordance with the present invention.  
       FIG. 2C  illustrates a second embodiment of an adjustable tray in accordance with the present invention.  
       FIG. 3A  illustrates an embodiment of a removable sidewall.  
       FIG. 3B  is an alternative removable sidewall having crown-shaped tabs.  
       FIG. 4A  is a cross-sectional view of an adjustable sidewall in a recess.  
       FIG. 4B  illustrates a removable sidewall positioned in indentations at a maximum channel length.  
       FIG. 4C  illustrates a removable sidewall positioned in indentations at a minimum channel length.  
       FIG. 5  illustrates an end wall having crown-shaped recesses.  
       FIG. 6  illustrates an indentation that can accommodate the sidewall of  FIG. 3B .  
       FIG. 7  illustrates a sidewall with crown-shaped tabs inserted into a tray in accordance with the present invention.  
       FIG. 8  is a perspective view of an embodiment of an adjustable tray with a wafer segment secured therein in accordance with the present invention.  
       FIG. 9A  is a perspective top view of a processing cover with a window for securing components within the storage tray of the invention.  
       FIG. 9B  is a perspective top view of an alternate processing cover for securing components within the storage tray of the invention.  
       FIG. 10  is a preferred embodiment of a transparent cover.  
       FIG. 11  is a perspective view of stackable trays and their covers.  
       FIG. 12  is a cross-sectional view of  FIG. 11  taken generally along line A-A thereof. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
      The present invention encompasses an adjustable tray for holding components during processing or shipping. Components may include unfinished die, wafer segments, semiconductor devices, and other material contained on a strip. Components stored in accordance with the present invention may be subject to various process steps, including testing, inspection, washing and chemical treatment. These process steps are wholly or partially performed in an automated computer-controlled environment. The primary purpose of the invention is for use as a storage and processing tray. However, when the tray is provided with a solid cover, the present invention may also be used as a shipping tray.  
       FIG. 2A  illustrates a tray in accordance with a first embodiment of the invention. Recesses  24 A,  24 B and  22 A,  22 B are located on end walls  35  of the tray. The recesses are located at points (stop points) along the top surface of the end wall  35 . The distance from sidewall  15  to the recesses  22 ,  24  correspond substantially to the component length and the clearance space combined. The engagement of side wall  25  in tray frame  28  is shown in  FIGS. 2B-2C .  FIG. 2B  illustrates the engagement of side wall  25  with recesses  24 A/ 24 B for components on a short strip, hereinafter referred to as short bars. In this case, tab  40 A of adjustable side wall  25  engages with recess  24 A and tab  40 B engages with recess  24 B to form channels  45  for short bars.  FIG. 2C  illustrates the engagement of side wall  25  with recesses  22 A/ 22 B for components on a long strip, hereinafter referred to as long bars. Specifically, tab  40 A engages with recess  22 A while tab  40 B engages with recess  22 B to form channels suitable for receiving long bars. Accordingly, the same tray can be reused to process wafer segments of a different length by removing side wall  25  and placing it into a different pair of parallel recesses.  
      Stop points identify predetermined channels available for receiving the components. Components such as disk heads are inserted into one of the numbered channels  45 . Although only two possible regions are shown in  FIGS. 2A-2C  for engaging adjustable side wall  25 , more than two regions can be provided on the end walls  35  to accommodate a plurality of component sizes.  
      The present invention allows the same tray to be used for different lengths of wafer segments, such as disk head strips. In a first embodiment, as shown in  FIG. 2A , the invention comprises a tray  20  in the shape of a frame having a central opening that extends through the tray. Accordingly, it is not essential for tray  20  to have a floor. Frame  28  has a stationary sidewall  15  with a plurality of slots  50  and depressions  48  as shown in  FIG. 2A . Slots  50  are interposed with depressions  48 . Preferably sidewall  15  is a unitary structure with the frame. A removable sidewall  25  is placed opposite sidewall  15  in end walls  35  as shown in  FIG. 2B . The slots of sidewall  15  and the slots of sidewall  25  together form elongated channels  45  for receiving wafer segments.  
      Sidewall  25  preferably has an equal number of slots  50  and depressions  48  as sidewall  15 . Depressions  48  are for drainage purposes and do not receive wafer segments. Indeed, depressions  48  are an optional feature of the present invention.  
      The present invention is considered to have universal applications because it incorporates an adjustable sidewall  25 . The channel length is adjusted by moving sidewall  25  along parallel grooves ( FIG. 8 ) or by removing sidewall  25  from specific regions and reinserting it in a new position on the frame. Therefore, adjustable sidewall  25  can also be removable.  
      In each embodiment, the slot width is greater than the width of the wafer segment to ensure that the delicate features of the wafer segment are properly safeguarded. In a preferred embodiment, the slot width is greater than the width dimension of the wafer segment so that the slot width clearance, or free space between the slot width and the wafer segment is between 0.50 mm and 1.0 mm. In a more preferred embodiment, the clearance between the wafer segment and the slot width should be between 0.50 and 0.65 mm, inclusive.  
      The channel in the present invention preferably has a longitudinal dimension that is greater than the longitudinal dimension of the wafer segment. For a wafer segment that is approximately 57.5 mm in length, the distance between a slot on adjustable sidewall  25  and the corresponding slot on sidewall  15  is approximately 58 mm, while the distance between facing ribs  52  is approximately 55 mm for a tray. For a longer wafer segment—of approximately 70 mm in length—the distance between opposing slots is approximately 70.5 mm in length, while the distance between facing ribs is approximately 67 mm. To protect the contents of each tray, the channel depth should exceed the depth of the wafer segments. An optional cover may be placed on tray  20  to secure components loaded for testing, rinsing, or any other processing step.  
       FIG. 3A  illustrates one embodiment of sidewall  25 . Tabs  40 A,  40 B are located at terminal ends of side wall  25 . Tabs  40 A and  40 B permit side wall  25  to securely engage with recesses  22 A,  22 B or  24 A,  24 B in tray  20  of  FIG. 2A . A cross section of tab  30  inserted into recess  22  is provided in  FIG. 4A . It is apparent from  FIG. 4A  that the surface  40  of tab  30  is flush with the upper surface of frame  28  during use.  FIG. 4A  also illustrates the depth at which adjustable sidewall  25  is preferably placed to provide a suitable storage tray. It is, however, not essential for the tabs to extend horizontally from the upper surface of side wall  25  as shown in  FIG. 3A . Tabs  40 A/ 40 B can instead extend horizontally from the lower surface of side wall  25  and be press fitted into the underside of a tray frame to form a channel with sidewall  15 .  
      Both tabs  40 A/ 40 B and recesses  22 A/ 22 B,  24 A/ 24 B are not limited to the shapes shown in  FIG. 3A . Any shape that would allow a tab to mate with a recess in a press fit would be suitable for practicing the present invention. For example, the tabs may be crown shaped as shown in  FIG. 3B . The recess for crown-shaped tabs would have a crown-shaped opening as shown in  FIG. 5  so that tabs  40 A/ 40 B mate to the recesses with a press fit. After engagement with the recess, adjustable sidewall  25  can optionally be secured to the tray frame with a hollow cover.  
       FIG. 4B  illustrates a second embodiment for providing a universal storage tray. An indentation  54  is provided having rear corners with an acute angle on a first wall of the frame, and a similar indentation  55  is provided on an opposing wall. The rear corners have an acute angle to receive the terminal ends of the tabs shown in  FIG. 3A . The channel is adjusted by moving side wall  25  to a desired position. For example, adjustable side wall  25  may be positioned to the extreme left of indentations  54  and  55  as shown in  FIG. 4B  to receive long bars from wafers, i.e. wafer segments substantially corresponding to the maximum channel length of the tray.  
      Accordingly, the removable sidewall of  FIG. 3A  would be suitable for use with the tray of  FIG. 4B . Indentations  54  and  55  generally have a contour conforming to the outer periphery of the tabs. As with the tabs, the indentations are not limited to a specific shape. An example of an alternative indentation is shown in  FIGS. 6 and 7 . Sidewall  25  of  FIG. 3B  with crown-shaped tabs would be suitable for use with the trays shown in  FIGS. 6 and 7 .  
      The indentations  54 ,  55  of the present invention may be configured to have a serrated upper edge in end wall  35  as shown in  FIG. 6  to locate the tab in more than two precise locations. Moreover, the indentations may have a numerical index  70  in accordance with  FIG. 7 , which identifies which recess corresponds to which channel length.  
       FIG. 7  illustrates an indentation with a plurality of marked spaces shown in 2.00 mm intervals. For example, placing the tabs of sidewall  25  into parallel spaces of opposing end walls marked with 58.2 mm will form a longitudinal channel that is 58.2 mm in length. It is understood that the indentation may have an interval spacing greater than or less than 2 mm. However, it is preferred that the indentation have equally spaced intervals.  
       FIG. 8  illustrates still another embodiment of the present invention. In  FIG. 8 , sidewall  25  is adjusted by sliding it along a groove  95 . The grooves extend within the entire range of end walls  35 . Accordingly, this embodiment enables sidewall  25  to be fully adjustable along the full range of the channel.  
      The adjustable sidewall  25  mates with the grooves through an alignment mechanism (not shown) on each terminal end. Non-limiting examples of suitable alignment mechanisms include a detent, a protrusion, a gear, a flange, or a roller. Grooves  95  are configured to complementarily mate with the alignment mechanism to thereby enable sidewall  25  to slide smoothly within end walls  35 .  
      After sidewall  25  is positioned at its preferred location in grooves  95 , one or more disk head strips  42 , are then manually placed into the channels. After the disk heads are fully processed, sidewall  25  is adjusted to allow removal of the disk heads from tray  20  for packaging. The channels in tray  20  may then be adjusted for processing disk head segments having a different length by repositioning sidewall  25  to a new location.  
      It is contemplated that the trays of this invention will be moved single file along a surface where individual wafer segments are being processed. The trays remain at a specific processing station until each of the wafer segments has been processed. For example when the wafer segments of a specific tray are being tested, each wafer segment will be lifted from a channel by a test handler, individually tested, and then returned to the same channel.  
      Methods for securing the contents in the trays of the present invention will now be discussed. When sidewall  25  is placed in its desired position, a hollow cover may be provided to secure components within tray  20 . The hollow cover is preferably thermoformed out of a clear polymeric material to form transparent covers. In a preferred embodiment, the hollow cover is manufactured from Stat-Tech™ M312, available from Noveon located in Cleveland, Ohio.  
      The type of cover used in accordance with the present invention will depend on whether the components are ready for shipping or not.  FIG. 9A  illustrates a process cover that would be appropriate for securing long bar components. Cover  80  is shown having the shape of a frame with an open window  82 . Window  82  has peripheral edges  92  and  93 . Edges  92  are superimposed on an upper portion of slots  50  when cover  80  is snapped onto tray  20 . It is therefore understood that the complete top surface of slots  50  need not be concealed by peripheral edges  92 . A process cover for short bar components would have a smaller window than the cover of  FIG. 9A  because slots  50  are closer together when short bar components are stored.  FIG. 9B  shows a process cover for short bar components. The window in  FIG. 9B  has peripheral edges  92  that can be superimposed over an upper portion of slots  50  in a similar manner as in  FIG. 9A . Process covers with an open window  82  allow the components to be washed, inspected, tested and subject to various other processing steps.  
      All of the covers discussed herein are equipped with protrusions on at least two opposing walls. The protrusions  33  are preferably located on the interior of hollow cover  80 . Detent  31  on tray  20  and protrusions  33  on cover  80  snap together to form a module that securely captures the components in place.  
       FIG. 10  illustrates another type of process cover suitable for securing wafer segments in short bar or long bar recesses. Cover  80  in  FIG. 10  has rectangular gaps  88  and narrow slats  86  extending between end walls  35 . The narrow slats  86  are located at periodic intervals of the cover, and serve to capture the components in place. Slats  86  preferably are superimposed over the slots of sidewalls  15  and  25  to prevent the wafer segments from exiting their channels. Rectangular gaps  88  are interspersed between the slats  86  to allow the tray contents to be sprayed or washed during processing. The rectangular gaps  88  should be as wide as possible to allow the largest possible surface area of the wafer segments to be exposed for processing.  
      The present invention is not restricted to using covers with a window. In fact, the cover could be made of a solid material that is transparent.  FIG. 11  illustrates a stack of covered trays. In this embodiment, cover  80  is thermoformed from a clear material, such as Stat-Tech™ M312. The entire face of tray  20  is visible through cover  80 , including numerical index  70 . Of course, the trays of the present invention are stackable whether covered or uncovered.  
       FIG. 12  is a cross-sectional view of  FIG. 11  along line A-A. Each cover  80  in the stack has beveled edges  87  that fit over the perimeter of each tray  20 . Dust and other contaminants can not enter trays covered with solid cover  80 . Consequently, such a cover would be ideal for shipping components to customers, manufacturers, and contractors.  
      When it is necessary to adjust the channel, cover  80  must be removed. Sidewall  25  is then moved to the desired stop point on the indentations or grooves, before being secured with a cover. Alternatively, the sidewall can be adjusted by extracting tabs  40 A,  40 B from recesses  22 A,  22 B or  24 A,  24 B and inserting sidewall  25  into another pair of recesses. Afterwards, an optional cover may be attached to the tray depending on how the tray will be used.  
      In each of the embodiments, the adjustable sidewall may be provided with an index or numerical scale to identify the number of channels occupied, the length of the items loaded in the tray, or to otherwise facilitate tracking of a specific component strip.  
      The examples described herein are solely representative of the present invention. It is understood that various modifications and substitutions may be made to the foregoing examples without departing from either the spirit or scope of the invention. In some instances certain features of the invention will be employed without other features depending on the particular situation encountered by the ordinary person skilled in the art. Moreover the trays are not restricted to dimensions that hold wafer segments of a maximum length of 70 mm. Accordingly, the invention can be applied to trays that form channels of a different dimension than those described herein. It is therefore the intent that the invention not be limited to the particular examples disclosed herein.