Abstract:
A stacking tray for electrical components, such as integrated circuits, particularly those of the ball grid array (BGA) type. The tray is stackable and includes an upper side and a lower side. Both upper and lower sides of the trays include support elements forming ledges and ridges to support the integrated circuit element and stabilize the integrated circuit element in the X-Y directions. In the unstacked configuration, whether the tray is presented in the right side up or upside down configuration, the integrated circuit elements are stabilized in the X-Y directions at two diagonally opposed corners, and hence all four sides of the chip. In a stacked configuration, the laterally inwardly offset ridges of a tray immediately downwardly adjacent from the integrated circuit restrain and stabilize the integrated circuit in the X-Y directions by engaging a first pair of diagonally opposed corners of the integrated circuit.

Description:
This application claims priority from provisional application Ser. No. 60/576,694, filed on Jun. 2, 2004. 

   BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to a tray for integrated circuits, particularly those of the ball grid array (BGA) type. The tray is stackable and includes an upper side and a lower side, wherein the upper and lower sides of each tray have storage pocket areas that align with one another when trays are stacked. More particularly, both upper and lower sides of the trays include support elements forming ledges of equal uniform height to restrain and stabilize the integrated circuit chip in the Z-direction (perpendicular to the floor) and ridges restrain and stabilize the integrated circuit chip in the X-Y direction (parallel to the floor). The ridges on one side of the tray stabilize a first pair of diagonally opposed corners of the integrated circuit chip while ridges on the other side of an adjacent tray stabilize a second pair of diagonally opposed corners of the integrated circuit chip. 
   2. Description of the Prior Art 
   In the prior art, it is known to use stackable trays for the storage and transportation of integrated circuits, particularly ball grid array (BGA) integrated circuits. These stackable trays typically form discrete storage pockets for engaging individual chips. Moreover, these trays are sometimes used as a carrier to position the chips for inspection and automated assembly apparatus. Inspection usually requires that the balls face upward whereas assembly generally requires that the balls face downward. Therefore, it is important that the integrated chips are stabilized in the X-Y directions whether the chips are in a tray that is in the right side up or upside down configuration. That is, the trays should be “flippable” or capable of supporting chips in either orientation. 
   Moreover, it is imperative that these trays provide substantial mechanical and electrostatic/electromagnetic protection for the chips. 
   Some examples of the prior art stackable trays can be found in U.S. Pat. No. 5,400,904 entitled “Tray for Ball Terminal Integrated Circuits”, issued to Maston et al. on Mar. 28, 1995; U.S. Pat. No. 5,103,976 entitled “Tray for Integrated Circuits with Supporting Ribs”, issued to Murphy on Apr. 14, 1992; U.S. Pat. No. 5,080,228 entitled “Integral Carrier and System for Electrical Components”, issued to Maston et al. on Jan. 14, 1992; U.S. Pat. No. 5,000,697 entitled “Carrier System for PGA Electrical Components”, issued to Murphy on Mar. 19, 1991; U.S. Pat. No. 4,765,471 entitled “Electrical Component Carrier”, issued to Murphy on Aug. 23, 1988. 
   An additional example can be found in commonly owned U.S. patent application Ser. No. 10/414,617, filed on Apr. 16, 2003 entitled “Stackable Tray for Integrated Circuits with Corner Support Elements and Lateral Support Elements Forming Matrix Tray Capture System”. 
   OBJECTS AND SUMMARY OF THE INVENTION 
   It is therefore an object of the present invention to provide trays which can be stacked to provide storage pockets for electronic chips, such as, but not limited to, BGA (ball grid array) chips. 
   It is a further object of the present invention to provide trays which can present electronic chips for automated manufacture (such as “pick and place”) stabilized in the X-Y directions, whether the trays are right side up or upside down. That is, it is an object of the present invention to provide trays which are “flippable”. 
   It is therefore a still further object of the present invention to provide trays for the storage, transportation and automated placement of electronic chips, wherein the trays provide improved mechanical, electrostatic and electromagnetic protection of the chips therewithin. 
   It is therefore a still further object of the present invention to provide trays for electronic chips which achieve the above-identified objects while maintaining a simple shape achieved with simple molding procedures and reduced material requirements. 
   These and other objects are attained by providing a tray wherein upper and lower sides of the tray include at each storage pocket of the tray, support elements with ledges of equal uniform height to stabilize the corners of integrated circuit chips in the Z-direction and ridges which stabilize the corners of integrated circuit chips in the X-Y plane. For each pair of adjacent storage pockets, with respect to one storage pocket, the ridges are laterally inwardly offset on two diagonally opposing corners to define the storage pocket for the chips and to restrain and stabilize the integrated circuits in the X-Y directions (parallel to the floor of the trays) and the ridges are laterally outwardly offset on the remaining two diagonally corners of the storage pockets to provide the X-Y stabilization in the adjacent storage pocket. The ledges on the upper surface of the tray are directly aligned with the ledges on the lower surface of the tray thereby providing stabilization in the Z-direction by capturing the chip between the ledges of support elements of adjacent trays. However, the ridges on the ledges of the upper surface of the tray are offset in an opposite lateral direction from the ridges on the ledges of the lower surface of the tray. 
   In the unstacked configuration, this results in the integrated circuit chip being stabilized in the X-Y directions at two diagonally opposed corners, and hence all four sides, whether the tray is presented in the right side up or upside down configuration. This is particularly important for automated placement applications, such as “pick and place”. 
   In a stacked configuration, the laterally inwardly offset ridges of a tray immediately downwardly adjacent from the integrated circuit restrain and stabilize the integrated circuit in the X-Y directions by engaging a first pair of diagonally opposed corners of the integrated circuit. Likewise, the laterally inwardly offset ridges of a tray immediately upwardly adjacent from the integrated circuit restrain and stabilize the integrated circuit in the X-Y directions by engaging the other second pair of diagonally opposed corners of the integrated circuit. Therefore, in the stacked configuration, all four corners of the integrated circuit chip are restrained and stabilized when engaged between successive stacking trays. 
   A second embodiment achieves similar results by alternating between, firstly, support elements with ledges which provide Z-direction stabilization to one corner of all adjacent storage pockets and, secondly, support elements with ledges which provide Z-direction stabilization and ridges which provide X-Y stabilization to one corner of all adjacent storage pockets. 
   The tray conforms to JEDEC standards which sets the tray outline, storage pocket locations, outer rail height and stacking configuration which permits an integrated circuit chip seated in a full storage pocket defined by a lower tray storage pocket and an upper tray storage pocket to be restrained and stabilized in the Z direction by being between the ledges of the support elements of the immediately upwardly adjacent tray and the ledges of the support elements of the immediately downwardly adjacent tray. 

   
     DESCRIPTION OF THE DRAWINGS 
     Further objects and advantages of the invention will become apparent from the following description and claims, and from the accompanying drawings, wherein: 
       FIG. 1  is a top perspective view of the stackable tray of the present invention. 
       FIG. 2  is a detailed portion of the perspective view of  FIG. 1 . 
       FIG. 3  is a bottom perspective view of the stackable tray of the present invention. 
       FIG. 4  is a detailed portion of the perspective view of  FIG. 3 . 
       FIG. 5  is a top plan view of the stackable tray of the present invention. 
       FIG. 6  is a side plan view of the stackable tray of the present invention. 
       FIG. 7  is a cross-sectional view along plane  7 - 7  of  FIG. 5 . 
       FIG. 8  is a bottom plan view of the stackable tray of the present invention. 
       FIG. 9  is a detailed portion of the cross-sectional view of  FIG. 7 . 
       FIG. 10  is a plan view of a portion of the corner storage pocket formed by the upper side of the stackable tray of the present invention. 
       FIG. 11  is a cross-sectional view along plane  11 - 11  of  FIG. 10 . 
       FIG. 12  is a cross-sectional view along plane  12 - 12  of  FIG. 10 . 
       FIG. 13  is a plan view of a portion of the corner storage pocket formed by the lower side of the stackable tray of the present invention. 
       FIG. 14  is a plan view of an interior portion of the upper side of the stackable tray of the present invention, including the interior vacuum chambers. 
       FIG. 15  is a cross-sectional view along plane  15 - 15  of  FIG. 14 . 
       FIG. 16  is a cross-sectional view of two stacked trays of the present invention, with an integrated circuit engaged therebetween. 
       FIG. 17  is a perspective view of two stacked trays of the present invention, with an integrated circuit engaged therebetween. 
       FIG. 18  is a perspective view of two inverted stacked trays of the present invention, with an integrated circuit engaged therebetween. 
       FIG. 19  is a top plan view of the second embodiment of the stackable tray of the present invention. 
       FIG. 20  is a bottom plan view of the second embodiment of the stackable tray of the present invention. 
       FIG. 21  is a plan view of a portion of the corner storage pocket formed by the upper side of the second embodiment of the stackable tray of the present invention. 
       FIG. 22  is a cross-sectional view along plane  22 - 22  of  FIG. 21 . 
       FIG. 23  is a cross-sectional view along plane  23 - 23  of  FIG. 21 . 
       FIG. 24  is a plan view of a portion of the corner storage pocket formed by the lower side of the second embodiment of the stackable tray of the present invention. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
   Referring now to the drawings in detail wherein like numerals indicate like elements throughout the several views, one sees that  FIG. 1  is a top perspective view of the tray  10  of the present invention. Tray  10  conforms to the standards of JEDEC and hence is bounded by long sides  12 ,  16  and short sides  14 ,  18  with interior structure provided by planar floor  20 . Sides  12 ,  14 ,  16 ,  18  are bounded by downwardly extending peripheral skirt  22  (see  FIG. 9 ) which further includes upper indentation  24  for receiving the peripheral skirt  22  of an upwardly adjacent tray thereby allowing the trays  10  to be stacked. Flanges  26 ,  28  are provided on short sides  14 ,  18  offset from one another in accordance with JEDEC to provide indication of the front and back of the tray. As noted, the entire peripheral structure, including peripheral skirt  22 , upper indentation  24  and flanges  26 ,  28 , is made in accordance with JEDEC standards to provide for standardized automated handling of tray  10 . 
   Corner  30  is formed at the intersection of sides  12 ,  14 . Corner  32  is formed at the intersection of sides  14 ,  16 . Corner  34  is formed at the intersection of sides  16 ,  18 . Corner  36  is formed at the intersection of sides  12 ,  18 . Flat (that is, without ridges) L-shaped support elements  40  are formed on the upper surface ( FIGS. 1 ,  5  and  10 ) inwardly adjacent from corners  32 ,  36  and are formed on the lower surface ( FIGS. 3 and 8 ) inwardly adjacent from corners  30 ,  34 . Ridged L-shaped support elements  42  are formed on the upper surface ( FIGS. 1 ,  2  and  5 ) inwardly adjacent from corners  30 ,  34  and are formed on the lower surface ( FIGS. 3 ,  4 ,  8  and  13 ) inwardly adjacent from corners  32 ,  36 . T-shaped support elements  44  are formed inwardly adjacent from sides  12 ,  14 ,  16 ,  18 , and X-shaped support elements  46  are formed in the interior of tray  10  thereby defining storage pockets  101 - 124  which are configured in rows and columns within the rectangular shape of tray  10 , which could likewise be provided in a square or other shape. Storage pockets  105 ,  111 ,  114 ,  120  include a solid planar floor  20  thereby forming vacuum storage pockets to permit vacuum operated equipment to couple to the tray whereas the remaining storage pockets have a substantial portion of planar floor  20  removed. 
   As seen in  FIGS. 5 ,  8 ,  10  and  13 , X-shaped support elements  46  include two laterally offset L-shaped ridges  50 ,  52 . Laterally offset L-shaped ridges  50 ,  52  are oriented to be laterally inwardly offset for a given storage pocket and hence serving to stabilize a chip in that pocket while being laterally outwardly offset for an adjacent storage pocket and hence not serving a stabilizing function for the adjacent pocket. For instance, in  FIG. 10 , laterally offset L-shaped ridge  50  is laterally inwardly offset for storage pocket  119  so as to capture the corners of a chip in pocket  119 , but is laterally outwardly offset for storage pockets  120 ,  122  thereby serving little or no stabilizing function for a chip in these pockets. Likewise, laterally offset L-shaped ridge  52  of  FIG. 10  is laterally inwardly offset for storage pocket  123  but is laterally outwardly offset for storage pockets  120 ,  122 . This sequence of alternating inwardly and outwardly lateral offset is likewise well-illustrated in  FIG. 14 . Similarly, ridged L-shaped support elements  42  include laterally offset L-shaped ridges  54  which, as shown in  FIGS. 1 and 2 , are configured to be diagonally opposite from laterally inwardly offset L-shaped ridges  52  on the upper surface in storage pockets  101  and  124  and, as shown in  FIGS. 3 ,  4  and  13 , are configured to be diagonally opposite from laterally inwardly offset L-shaped ridges  52  on the lower surface in storage pockets  103  and  122 . Likewise, T-shaped support elements  44 , as shown in  FIGS. 10 and 13  include laterally offset L-shaped ridges  50  or  52  to be laterally inwardly offset at the diagonally opposing corner of a similar laterally inwardly offset L-shaped ridge  50  or  52  for a given storage pocket. 
   As can be seen from the cross-sectional views of  FIGS. 11 ,  12 ,  15  and  16  and perspective views  17  and  18 , the orientation of the laterally offset L-shaped ridges  50 ,  52  alternates between the top side of the tray  10  and the bottom side of the tray  10 , just as it alternates between adjacent storage pockets. Specifically, as seen in  FIG. 11 , for the X-shaped support element  44  shown, on the top side, L-shaped ridge  52  is laterally inwardly offset with respect to storage pocket  122  and outwardly offset with respect to storage pocket  119  while, on the bottom side, L-shaped ridge  50  is outwardly offset with respect to storage pocket  122  and inwardly offset with respect to storage pocket  119 . The resulting stacked structure, which can be used for shipping and transportation, provides that an integrated circuit chip  1000  (see  FIGS. 16-18 ) is laterally supported and stabilized in the X-Y direction within a storage pocket by having a first pair of diagonally opposed corners engaged by the laterally inwardly offset ridges  50 ,  52  of an immediately upwardly adjacent tray  10  and by having a second pair of diagonally opposed corners engaged by the laterally inwardly offset ridges  50 ,  52  of an immediately downwardly adjacent tray  10 . 
   Therefore, in this stacked configuration, all four corners of an integrated circuit chip  1000  are supported and stabilized in the X-Y directions by successive stacking trays  10 . Similarly, the integrated circuit chip  1000  is stabilized in the Z-direction (perpendicular to stacking tray)  10  by being engaged between the ledges formed by the support elements  40 ,  42 ,  44 ,  46  of adjacent stacking trays. 
   Moreover, when the trays  10  are unstacked, whether in a right side up or upside down configuration, the integrated circuit chips  1000  are stabilized in the X-Y direction at two diagonally opposed corners, thereby stabilizing all four sides of the chip. That is, the trays are “flippable”. This is particularly useful for automated placement of the integrated circuit chips  1000 , such as in a “pick and place” operation. 
   A second embodiment of tray  10  is disclosed in  FIGS. 19-24 . In this embodiment, X-shaped support elements alternate between X-shaped support elements  47  without support ridges (see  FIG. 21 ) and X-shaped support elements  49  with X-shaped support ridges  51  (see  FIG. 24 ). In this embodiment, the X-shaped support elements  47  (without support ridges) provide ledges for stabilization in only the Z-direction to integrated circuit chips in one corner of each of the four adjacent storage pockets. However, the X-shaped support elements  49  provide ledges for stabilization in the Z-direction and X-shaped ridges  51  provide stabilization in the X-Y direction to integrated circuit chips in one corner of each of the four adjacent storage pockets. Similarly, T-shaped support elements alternate between T-shaped support elements  41  without support ridges (see  FIG. 24 ) and T-shaped support elements  43  with T-shaped support ridges  45  (see  FIG. 21 ). The T-shaped support elements  41  (without ridges) provide ledges for stabilization in only the Z-direction to integrated circuit chips in one corner of each of the two adjacent storage pockets. Likewise, the T-shaped support elements  43  provide ledges for stabilization in the Z-direction and T-shaped support ridges  45  provide stabilization in the X-Y direction to integrated circuit chips in one corner of each of the two adjacent storage pockets. 
   As shown in  FIGS. 19-24 , L-shaped support elements  35  without support ridges are provided in corner storage pockets diagonally opposite from X-shaped support elements  47  (without support ridges). See storage pockets  101  and  122  in  FIG. 19 , the top view of the tray; storage pockets  103  and  124  in  FIG. 20 , the bottom view of the tray; and storage pocket  122  in  FIG. 21 , a detailed top view of the tray. Likewise, L-shaped support element  37  with L-shaped support ridges  39  are provided in corner storage pockets diagonally opposite from X-shaped support elements  49  (with support ridges  51 ). See storage pockets  103  and  124  in  FIG. 19 , the top view of the tray; storage pockets  101  and  122  in  FIG. 20 , the bottom view of the tray; and storage pocket  122  in  FIG. 24 , a detailed bottom view of the tray). The L-shaped support elements  35  (without support ridges) provide ledges for stabilization in only the Z-direction to the outward corner of integrated circuit chips in the adjacent corner storage pockets. Likewise, the L-shaped support elements  37  provide ledges for stabilization in the Z-direction and L-shaped support ridges  39  provide stabilization in the X-Y direction to the outward corner of integrated circuit chips in the adjacent corner storage pockets. 
   The resulting configuration, when the trays of the second embodiment are stacked, results in all four corners of the integrated circuit chips stored therewithin to be stabilized in the X-Y direction at a first pair of diagonally opposite corners by the support elements of an upper tray and in the X-Y direction at a second pair of diagonally opposite corners by the support elements of a lower tray. Likewise, all four corners are stabilized in the Z-direction by the ledges of the support elements of both the upper tray and lower tray. Moreover, similarly to the first embodiment, the second embodiment provides a “flippable” configuration, and can be used in automated operations, such as “pick and place”. 
   Depending upon the thickness of the integrated circuit chip being stabilized, the thickness of the various support elements may vary as the integrated circuit chip is stored or stabilized between the support elements of two adjacent trays  10 . In the preferred embodiment, the integrated circuit chip is stored or stabilized at each corner by one support element with a support ridge and a like support element without a support ridge. That is, a support element with a support ridge is formed on the upper side of the tray directly above a like support element without a support ridge, and vice versa. 
   Thus the several aforementioned objects and advantages are most effectively attained. Although preferred embodiments of the invention have been disclosed and described in detail herein, it should be understood that this invention is in no sense limited thereby and its scope is to be determined by that of the appended claims.