Abstract:
A clip to secure trays in a stack including a platform, rails coupled to the platform to mate with tabs of at least bookending trays in the tray stack when the platform occupies a brake position thereof relative to the stack and an elastic brake element coupled to the platform and configured to be biased against the stack when the platform occupies the brake position to increase a mating friction between the rails and the tabs, the elastic brake element being actuatable against the bias to permit selective movement of the platform to and from the brake position, the selective movement solely actuating the elastic brake element.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
       [0001]    The present application claims the benefit of priority to a Canadian Patent Application Serial Number 2718863 entitled “TRAY HOLDER”, filed Oct. 29, 2010 with the Canadian Intellectual Property Office, the content of which is incorporated herein by reference in its entirety. 
       BACKGROUND 
       [0002]    Aspects of the present invention are directed to a tray holder and, more particularly, a holder for Joint Electron Devices Engineering Council (JEDEC) tray manipulation. 
         [0003]    Integrated circuit (IC) manufacturing processes use trays as the transport media to protect sensitive electronic devices from mechanical and electrostatic damage that may occur in typical manufacturing of IC devices. These processes take stacks of trays containing IC devices as input and output and require manual handling of stacks of trays between process steps and in and out of in-process storage. 
         [0004]    Common methods of handling stacks of trays containing IC devices presently include the use of individual or loose trays where the operator grabs stacks of 6-14 trays without any device to restrain the trays in the stack to transport the same from station to station. This technique runs the risk of operator error where trays come unstacked. Stainless steel baskets may be used where the operator stacks trays with IC devices in a stainless steel basket to transport the same from station to station. Metal baskets are typically required to withstand the thermal environment of some process steps, making them too heavy for routine tray stack handling. Extruded C-clips cut to length to bind two trays together have been used. 
         [0005]    An additional system involves the use of banding straps where the operator bands a stack of trays together using a secure bundle of trays to transport the IC devices from station to station. The use of a band which is buckled about the trays is not user friendly, however, in preparing the bundle or unbundling for single tray access. In particular, straps are often made of a plastic material and they may be applied at a remote strapping machine to tray stacks between each process operation (i.e., many times during production flow). The straps are then cut and removed at each operation. As such, a number of manipulations associated with strapping operations may be significant, the use of plastics and the inability to reuse the straps is ecologically unsustainable and tray contamination and scratch damage due to the strapping leads to tray deterioration. 
         [0006]    In view of these issues, a further system for securing trays in a stack was proposed in U.S. Pat. No. 5,421,455, in which a clip attaches individual trays in a stack, the trays being formed for nesting and with end tabs located on the opposite ends of the trays. According to the &#39;455 patent, the clip included a platform having a front and a rear surface and a leading and trailing edge, a plurality of spaced rails positioned parallel with each other positioned on the rear surface of the platform, the rails having a generally T-shape in cross-section, an end stop projecting from the trailing edge of the platform in a rearward direction for limiting the movement of the platform across the end of the stack of trays and latch means. The latch means were formed on the platform for locking the platform onto the end of a stack of trays and include a stop projecting in a rearward direction, biasing means to normally position the stop in a position projecting rearward from the rear surface of the platform and actuating means for moving the stop against said biasing means to move the stop from the rearward projecting position to a position in the plane of said rear surface. 
         [0007]    Since the actuating means are operable in a manner that is separate from the movement of the platform relative to the stack of trays, however, the connection of the clip to the stack of trays and the disconnection of the clip involves a two-step process whereby the user manipulates the platform and the actuating means separately and at the same time. That is, in order for the clip to be connected to a stack of trays, it is necessary for the user to move the platform along the tray ends and, at the same time, to pull the actuating means such that the stop does not project rearwardly. By contrast, in order for the clip to be disconnected, the actuating means must be pulled again such that the stop does not project rearwardly and such that the platform movement is permitted. These operations are unnecessarily complicated, time consuming and expensive. 
       SUMMARY 
       [0008]    In accordance with an aspect of the invention, a clip to secure trays in a stack is provided and includes a platform, rails coupled to the platform to mate with tabs of at least bookending trays in the tray stack when the platform occupies a brake position thereof relative to the stack and an elastic brake element coupled to the platform and configured to be biased against the stack when the platform occupies the brake position to increase a mating friction between the rails and the tabs, the elastic brake element being actuatable against the bias to permit selective movement of the platform to and from the brake position, the selective movement solely actuating the elastic brake element. 
         [0009]    In accordance with another aspect of the invention, a clip to secure nestable trays in a stack is provided and includes a platform, a plurality of rails protruding from the platform to engage with tray tabs to prevent movement of the platform relative to tray ends in first and second transverse directions, an edge stop projecting from the platform to limit movement of the platform across the tray ends in a third direction transverse to the first and second directions, a brake to inhibit movement of the platform relative to a tray stack and an elastic element to bias the brake toward the tray stack to increase friction of the slider and tab engagements, the brake including leading and trailing edge cams that permit movement of the platform across the tray ends in the third direction by encouraging movement of the brake against the bias during such platform movement. 
         [0010]    In accordance with another aspect of the invention, a clip to secure nestable trays in a stack is provided and includes a platform having front and rear surfaces and leading and trailing edges, a plurality of rails protruding from the rear surface to engage with tray tabs to prevent movement of the platform relative to tray ends in first and second transverse directions, an edge stop projecting from the trailing edge to limit movement of the platform across the tray ends in a third direction transverse to the first and second directions beyond a brake position, a brake to inhibit movement of the platform relative to a tray stack and an elastic element to bias the brake rearward from a platform plane to increase friction of the rail and tab engagements with the platform occupying the brake position, the brake including leading and trailing edge cams that permit movement of the platform to/from the brake position across the tray ends in the third direction by encouraging movement of the brake against the bias during such platform movement. 
     
    
     
       BRIEF DESCRIPTIONS OF THE SEVERAL VIEWS OF THE DRAWINGS 
         [0011]    The subject matter regarded as the invention is particularly pointed out and distinctly claimed in the claims at the conclusion of the specification. The foregoing and other aspects, features, and advantages of the invention are apparent from the following detailed description taken in conjunction with the accompanying drawings in which: 
           [0012]      FIG. 1  is a perspective view of a clip to secure nestable trays in a stack; 
           [0013]      FIG. 2  is a perspective view of the clip of  FIG. 1 ; 
           [0014]      FIG. 3  is a perspective view of the clip of  FIGS. 1 and 2  from a different angle; 
           [0015]      FIG. 4  is an enlarged side view of the clip and the nestable trays of  FIG. 1 ; 
           [0016]      FIG. 5  is a perspective view of nested clips to form a tray pile; and 
           [0017]      FIG. 6  is a plan view of the nested clips of  FIG. 5 . 
       
    
    
     DETAILED DESCRIPTION 
       [0018]    With reference to  FIGS. 1-4 , a clip  10  to secure nestable trays  11  in a stack  12  is provided. The trays  11  are nestable with one another and, in particular, may be Joint Electron Devices Engineering Council (JEDEC) trays. Where the trays  11  are JEDEC trays, they may be configured to support integrated circuit (IC) devices in rows and columns across the widths of the trays and they may substantially conform to the JEDEC standard for thick trays. That is, the trays  11  may be about 0.480 inches (12.2 mm) high, 5.35 inches wide, and 12.4 inches long with end tray tabs  31  to be described below that increase the total length to about 12.70 inches. Each nestable tray  11  may be formed with a lip  13  inset from the tray edge and extending around the upper edge of the nestable tray  11 , and with a recess  14  along the lower edge of the tray about its periphery such that the trays are readily stacked or nested with the lip on one engaging the recess of the next adjacent upper tray to retain the trays from shifting longitudinally or laterally in relationship to each other. 
         [0019]    The clip  10  includes a platform  20  having a front surface  21 , a rear surface  22  opposing the front surface  21 , a leading edge  23  and a trailing edge  24  opposing the leading edge  23 . The platform  20  further includes a plurality of rails  30 , an edge stop  40 , a brake  50  and an elastic element  60 . The rails  30  may be coupled to and may protrude from the rear surface  22  to engage with the tray tabs  31  of at least the top-most and the bottom-most trays  11  in the stack  12  (i.e., the bookending trays) to prevent movement of the platform  20  relative to the stack  12  generally or the tray ends in particular in first and second transverse directions, such as directions X and Z as shown in  FIG. 1 . It is to be understood that the rails  30  may engage with the tray tabs  31  of each tray  11  in the stack  12  not just the bookending trays. 
         [0020]    The edge stop  40  may project from the trailing edge  24  to limit movement of the platform  20  across the stack  12  in a third direction, such as the direction Y as shown in  FIG. 1 , which is transverse to the first and second directions beyond a brake position. The edge stop  40  may also be positioned on the rails  30  as well or another portion of the platform  20  as long as it is disposed to limit the movement of the platform  20  in the third direction. 
         [0021]    At least two or more rails  30  may be provided for each nestable tray  11  in the stack  12 . In particular, each rail  30  pair may be disposed on either side of the brake  50 . In this way, a torsional moment about the brake  50  may be limited by the rails  30  on either side of the brake  50 . Also, the tray tabs  31  and the rails  30  may each have substantially L-shaped complementary cross-sections and the platform  20  and the edge stop  40  may have respective lengths to extend substantially along an entire thickness of the stack  12 . 
         [0022]    The brake  50  inhibits movement of the platform  20  relative to the tray stack  12  and the elastic element  60  biases the brake  50  in a rearward direction from a plane of the platform  20  to thereby increase friction of the rail  30  and tab  31  engagements when the platform  20  occupies the brake position. The brake  50  may include a bulbous member  51  and leading and trailing edge cams  70  and  71 , having tapered and/or curved surfaces  701 ,  711 , respectively, that permit movement of the platform  20  to/from the brake position across the stack  12  in the third direction by encouraging movement of the brake  50  against the bias provided by the elastic element  60  during such platform  20  movement. The elastic element  60  may include a planar member  600  with the brake  50  disposed at a distal edge thereof. With this arrangement, a size of the bulbous member  51  and a length of the elastic element  60  may be provided such that the bulbous member  51  never protrudes from a plane of the forward surface  21  of the platform  20 . 
         [0023]    For a stack  12  of nestable trays  11 , the platform  20  may be slid across tray ends in a direction which is substantially parallel to a longitudinal axis of the platform  20  as defined from the leading edge  23  to the trailing edge  24  such that the rails  30  slideably engage with the tray tabs  31 . This engagement prevents movement of the platform  20  into and away from the stack  12  and along a thickness direction of the stack  12 , as the rails  30  and the tray tabs  31  each may have the substantially L-shaped complementary cross sections  26 . It is to be understood that the rails  30  and the tray tabs  31  need not have substantially L-shaped cross-sections and that the sliding of the platform  20  need not be in the direction described above. In fact, the rails  30  and the tray tabs  31  may have any complementary shapes and the movement of the platform  20  may be in any direction in accordance with those shapes. 
         [0024]    As the sliding progresses, the leading edge cam  70  of the brake  50  comes into contact with the near ends of the near-side tray tabs  31  such that the curvature or the taper of the leading edge cam  70  relatively smoothly absorbs the impact of the brake  50  with the near ends and, as the sliding progresses further, the leading edge cam  70  causes, in opposition to the bias of the elastic element  60 , the brake  50  to move away from the tray ends in, for example, the Y direction, as shown in  FIG. 1 . Then, as the brake  50  clears the near-side tray tabs  31 , the trailing edge cam  71  slides over the far ends of the near-side tray tabs  31  and allows for the return of the brake  50  to its normal position with the sliding continuing until the platform  20  occupies the brake position and the edge stop  40  abuts the stack  12  to prevent any further sliding. At this point, the brake  50  abuts the stack  12  in opposition to the bias of the elastic element  60  such that friction of the rail  30  and tab  31  engagements is increased sufficiently to prevent unselective movement of the platform out of the brake position. 
         [0025]    By contrast, when the platform  20  is to be removed from the brake position, the platform  20  may be slid in the reverse direction. In this case, the trailing edge cam  71  of the brake  50  comes into contact with the far ends of the near-side tray tabs  31  such that the curvature or the taper of the trailing edge cam  71  relatively smoothly absorbs the impact of the brake  50  with the far ends of the near-side tray tabs  31  and, as the sliding progresses further, the trailing edge cam  71  causes, in opposition to the bias of the elastic element  60 , the brake  50  to move away from the tray ends in, for example, the Y direction, as shown in  FIG. 1 . Then, as the brake  50  clears the near-side tray tabs  31 , the leading edge cam  70  slides over the near ends of the near-side tray tabs  31  and allows for the return of the brake  50  to its normal position with the sliding continuing until the platform  20  is completely removed from the stack  12 . 
         [0026]    The size and shape of the elastic element  60  must therefore be provided such that the bias provided by the elastic element  60  to the brake  50  is sufficient to maintain the platform in the brake position until, for example, a user selectively moves the platform out of the brake position. That is, the bias must increase the friction generated by the engagement of the rails  30  and the tray tabs  31  such that unselective sliding of the platform  20  is prevented. By the same token, the bias must permit the selective movement of the platform  20  by the user and therefore must not be excessively rigid. 
         [0027]    The platform  20  is formed to define windows  25  through which the nestable trays  11  in the stack  12  are at least partially visible. In this way, the contents of the stack  12  are observable and determined without disassembly or removal of any of the individual trays. 
         [0028]    With reference to  FIGS. 5 and 6 , the platform  20  is nestable with another platform  20  to form a tray stack pile  80 . As shown, the platform  20  includes complementary legs  81  and grooves  82 . The legs  81  protrude from a bottom surface of the platform  20  and the grooves  82  are recessed from a top surface of the platform  20 . With this configuration, when stacked, the platforms  20  are retained from shifting longitudinally or laterally in relationship to each other. 
         [0029]    In accordance with various embodiments, the platform  20  may be formed of a molded thermoplastic material. Similarly, the rails  30 , the edge stop  40  and the elastic element  60  may be integrally formed with the platform  20 . The brake  50  may be integrally formed with the elastic element  60 . 
         [0030]    While the disclosure has been described with reference to exemplary embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the disclosure. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the disclosure without departing from the essential scope thereof. Therefore, it is intended that the disclosure not be limited to the particular exemplary embodiment disclosed as the best mode contemplated for carrying out this disclosure, but that the disclosure will include all embodiments falling within the scope of the appended claims.