Patent Abstract:
A carrier tape for receiving, seating, storing and transporting components having an upper surface, a lower surface, four corners and four sidewalls. The tape includes a strip of material with a plurality of pockets. Each pocket includes a plurality of corner guides with angled engagement members for guiding, centering and supporting a component by its lower peripheral corner without any other contact between the component and the pocket. The pocket may include at least one support shelf positioned so as to contact a corner of the component upon misalignment of the component and thereby prevent further downward movement of the component in the pocket.

Full Description:
RELATED APPLICATIONS 
   The present application claims the benefit of U.S. Provisional Application No. 60/377,537 filed May 1, 2002, and herein incorporated by reference in its entirety. 

   FIELD OF THE INVENTION 
   This invention relates to component carrier tape, and more particularly to a component carrier tape having self-aligning pockets. 
   BACKGROUND OF THE INVENTION 
   Modern semi-conductors have grown to be extremely complex and are highly susceptible to damage from external influences, such as contaminants, mechanical shock, electrostatic discharges and physical contact. Accordingly, various types of carriers have been developed to protect the delicate semi-conductors as they are transported between the many process steps needed for production. Various types of carriers have been developed for this purpose and are known in the art, including matrix and chip trays designed to carry a batch of components, as well as carrier tapes which are designed to carry the components in a continuous fashion. 
   Integrated circuit components which must be properly handled and transported include pin grid array (PGA), bare die, bump die, non-radial chip scale packing, ball grid arrays (BGA), and other leadless chip packages. These packages typically have a square or rectangular periphery with a flat upper surface, a flat lower surface, and generally have a relatively thin planar housing. Four side surfaces extend around the rectangular periphery. A lower peripheral corner extends around the periphery at the inner section of the sidewalls and lower surface. 
   The BGA is currently a popular integrated circuit package. BGA integrated circuits are characterized by the thin planar housing and a plurality of external terminals on the lower surface of the housing. Each external terminal comprises a small solder ball. Like earlier pin grid array integrated circuit packages, the solder ball terminals in a BGA integrated circuit package can be arranged in a two-dimensional array. However, the terminal density in a BGA integrated circuit package is greater than attainable then with PGA integrated circuit packages. 
   When transporting BGA integrated circuit packages, it is important that the solder ball terminals of the package be prevented from contacting the surface of the carrier device to prevent damage to the BGA package. Tray type carriers have been developed to meet this need. For example, in U.S. Pat. No. 5,791,486 (Brahmbhatt), owned by the owners of the present invention and fully incorporated herein by reference, a tray for integrated circuit components is disclosed having a pocket design wherein the component is supported above the bottom of the pocket by the lower peripheral corner of the component, and wherein no portion of the component terminals are in contact with the surfaces of the tray. 
   What is still needed in the industry, however, is a carrier tape wherein a component can be supported within a pocket of the carrier tape with limited contact between the carrier tape and the component so that the terminals of the component are not in contact with the tape. 
   SUMMARY OF THE INVENTION 
   The present invention substantially meets the aforementioned needs of the industry. A carrier tape for storing and transporting integrated circuit components is formed from a strip of material in which pockets are formed for receiving an integrated circuit component. Pockets are generally square or rectangular and have a corner design allowing point support of the component at its lower peripheral corner and without contact of the device terminals with any surface within the pocket or of the tape. 
   The invention may also include a pocket design for a carrier tape, matrix tray or chip tray in which the pocket corners have self-aligning features as described in U.S. Pat. No. 5,791,486 and in which the corner is provided with a failsafe shelf for supporting a component at its corner if the component becomes misaligned or is upset within the pocket. 
   The invention thus includes a carrier tape for receiving and seating a plurality of components, each having an upper surface, a lower surface, four corners, and a periphery with four side surfaces transverse to and intersecting the lower surface at a lower peripheral corner extending around the component. The carrier tape includes a flexible body portion having a top surface. A plurality of pockets is formed in the flexible body portion, the pockets positioned for receiving and confining the component. Each pocket has an interior, four corners, and four sides, each of the corners having a corner guide including a pair of component contact portions positioned on an incline so that the component contact portions slope toward the interior of the pocket. Each component contact portion includes a guide-in portion, a component seating portion, and a subordinate portion below the seating portion. The incline is continuous through the guide-in portion, the seating portion, and the subordinate portion, whereby when the component is engaged with the seating portion, only the lower peripheral corner of the component is in contact with the body portion. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a plan view of an integrated circuit component. 
       FIG. 2  is a side elevational view of the integrated circuit component of  FIG. 1   
       FIG. 3  is a perspective view of a single pocket of an embossed carrier tape according to the present invention. 
       FIG. 3A  is an enlarged view of the corner of the pocket depicted in  FIG. 3 . 
       FIG. 4  is a top plan view of a section of the embossed carrier tape according to the present invention. 
       FIG. 5  is a longitudinal sectional view at the embodiment shown in  FIG. 2 . 
       FIG. 6  is a transverse sectional view of the embodiment shown in  FIG. 2 . 
       FIG. 7  is a sectional view of a pocket corner of the embodiment shown in  FIG. 4 . 
       FIG. 8  is a perspective view of a single pocket of an alternative embodiment of the embossed carrier tape of the present invention. 
       FIG. 8A  is an enlarged view of the corner of the pocket depicted in  FIG. 8 . 
       FIG. 9  is a top plane view of the embodiment of  FIG. 6 . 
       FIG. 10  is a longitudinal sectional view of the embodiment of  FIG. 7 . 
       FIG. 11  is a transverse sectional view of the embodiment of  FIG. 7 . 
       FIG. 12  is a sectional view of a pocket corner of the embodiment of  FIG. 9 . 
       FIG. 13  is a plan view of an embodiment of a carrier tape. 
       FIG. 14  is a transverse sectional view of the embodiment of  FIG. 13 . 
       FIG. 15  is a close-up of the transverse sectional view of  FIG. 14 . 
       FIG. 16  is a plan view of an alternative embodiment of a carrier tape. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
   Depicted in  FIGS. 1 and 2  is a component  100  in the form of a ball grid array (BGA) integrated circuit  102 . Component  100  includes four side surfaces  104 , an upper side  106  having an upper planar surface  108 , and a bottom side  110  with a bottom planar surface  112 . Bottom side  110  may include an array of terminals  114 . Component  100  also has corners  116 , each of which has a tip  118 . A lower peripheral corner  120  is formed by the intersection of side surfaces  104  and bottom planar surface  112 . Although component  100  is depicted herein as a BGA device, it will of course be appreciated that component  100  may also be any other similarly configured component such as a pin grade array (PGA), bare die, bump die, non-radial chip scale package, or other leadless chip package. 
   In  FIGS. 3–7  is depicted a preferred embodiment of a carrier tape  122  of the present invention. Carrier tape  122  generally includes a flexible body  124  in the form of a long strip of material  126  in which device pockets  128  are arranged seriatim in a longitudinally oriented array. The tape has a top surface  129 , and an opposing bottom surface (not depicted). Sprocket holes  130  are arranged along one or both lateral margins  132 ,  134 , of carrier tape  122  to enable the tape to be moved by automated equipment. 
   Device pockets  128  are defined by a pair of opposing sidewalls  136 , a pair of opposing end walls  138  and pocket bottom  140 . Pocket corners  142 , described further hereinbelow, may be substantially as described as in U.S. Pat. No. 5,791,486 (Brahmbhatt), and provide support for a component  100  disposed in the pocket  128  by contact with the lower peripheral corner  120  of the component. An aperture  144  may be provided in pocket bottom  140  to enable access with automated handling apparatus, or to enable the application of vacuum for holding a component  100  in the pocket  128 . 
   In the embodiment of  FIGS. 3–7 , each pocket corner  142  includes a corner guide  146 , which is V-shaped with two component engagement portions  148 ,  150 , joined at a junction  152 . Both the component engagement portions  148 ,  150 , have an inner first face  154  facing the interior  156  of the pocket  128  and a second face  158  generally upright and intersecting the first face  154  at a ridge  160 . The ridge  160  constitutes an inclined component contact portion  162  with a guide-in portion  164 , a seating portion  166 , and a subordinate portion  168  below the seating portion  166 . The ridge  160  may be rounded as depicted. 
   The inner first faces  154  and second faces  158  thus cooperate to form an intersection shaped as a ridge  160  to support the lower peripheral corner  120  of the component  100  and to center the corner  116  between the component engagement portions  148 ,  150 . More specifically, when the component  100  is placed in the pocket  128 , the lower peripheral corner  120  will slide downwardly and inwardly along the ridges  160  of the component engagement portions  148 ,  150 , until a point is reached at which further downward and inward motion of the lower peripheral corner  120  is prevented by the ridges  160 . Because the inner faces  154 ,  158 , have the same mirror image orientation relative to the pocket bottom  140 , the corner  116  will come to rest centered between the component engagement portions  148 ,  150 . Also, with the component at the seating portion  166 , the tip  118  of the corner  116  will be separated from the junction  152  so that the component  100  does not touch the junction  152 . 
   The component engagement portions  148 ,  150 , extend or angle toward the adjacent pocket corner  142  as the ridge  160  slopes toward the top surface  129 . Although ridge  160  is depicted as linear it may also be curved. The orientation of ridge  160  provides improved component seating beyond that of a ridge orientation directly perpendicular to the edge of the component. The ridges  160  angling toward the pocket corner  142  urge the component corner downward and into the corner  142  for proper seating. 
   Carrier tape  122  may be formed from any suitable polymer material. Currently it is most preferred that polystyrene material be used, and it is also currently most preferred that the material be carbon loaded to provide electrical conductivity and corresponding static electricity dissipation capability. Pockets  128  may be formed in carrier tape  122  by any suitable method. Currently it is most preferred that pockets  128  be embossed. 
   In operation, a component  100  may be disposed in each pocket  128  of carrier tape  122 . When the component is disposed in the pocket  128  at the seating portion  166 , the bottom planar surface  112  of the component  100  will be co-planar with a substrate plane  168  and any terminals  114  of the component  100  will be held spaced apart from pocket bottom  140 . The component  100  contacts carrier tape  122  only at lower peripheral corner  120 . 
     FIGS. 8–12  depict a currently most preferred embodiment of the carrier tape  122  according to the present invention. In this embodiment, pocket corners  142  are as described above with the addition of shelf  170 . Shelf  170  serves as a failsafe support should a component  100  become misaligned or be upset while disposed in pocket  128 . 
   In normal operation, the bottom surface of a component disposed in pocket  128  is co-planar with substrate plane  168  as previously described and as depicted in  FIGS. 10–12 . In this position, the bottom planar surface  112  of component  100  is not in contact with shelf  170 . If component  100  should become slightly misaligned in pocket  128 , however, one or more corners  116  of component  100  will contact shelf  170  preventing further downward movement of the integrated circuit component  100  while still holding terminals  114  away from contact with pocket bottom  140 . 
   Shelf  170  may be used with any of the carrier tape pocket embodiments described herein. In addition, it will be readily appreciated that shelf  170  may be incorporated in any of the pocket corner arrangements of U.S. Pat. No. 5,791,486, previously incorporated by reference herein. Thus, the failsafe feature provided by shelf  170  described above may be provided in other types of carriers, such as matrix trays and chip trays. 
   Alternative embodiments of carrier tape  122  are depicted in  FIGS. 13–16 . In one embodiment shown in  FIG. 13-15 , carrier tape  122  includes pocket corners  172 . On both sides of pocket corner  172  is a component engagement member  174 . Typically, component engagement member  174  comprises an angled component contact surface  176  angled toward pocket bottom  140 . When component  100  is properly seated within pocket  128 , side surface  104  is generally parallel to a projecting engagement member surface  178  while bottom planar surface  112  is generally parallel to pocket bottom  140 . 
   An embodiment of carrier tape  122  including alternative component engagement members  180  is depicted in  FIG. 16 . Component engagement members  180  include an angled component contact surface  182  angled toward pocket bottom  140 . Component engagement members  180  extend along a substantial portion of opposing sidewalls  184  and opposing end walls  186 . When integrated circuit component  100  is properly positioned within pocket  128 , lower peripheral corner  120  rests on rests evenly on angled component contact surface  182  such that bottom planar surface  112  is generally parallel to pocket bottom  140 . 
   The present invention may be embodied in other specific forms without departing from the spirit of the essential attributes thereof; therefore, the illustrated embodiments should be considered in all respects as illustrative and not restrictive.

Technology Classification (CPC): 7