No lead package with heat spreader

Abstract

A no-lead electronic package including a heat spreader and method of manufacturing the same. This method includes the steps of selecting a matrix or mapped no-lead lead frame with die receiving area and leads for interconnect; positioning an integrated circuit device within the central aperture and electrically interconnecting the integrated circuit device to the leads; positioning a heat spreader in non-contact proximity to the integrated circuit device such that the integrated circuit device is disposed between the leads and the heat spreader; and encapsulating the integrated device and at least a portion of the heat spreader and leads in a molding resin.

1 . A method for the manufacture of a no-lead electronic package, comprising:
 providing a lead frame having features including a plurality of leads terminating about a central aperture;   positioning an integrated circuit device within said central aperture, the integrated circuit device having an electrically active face;   electrically interconnecting said integrated circuit device to said leads;   positioning a heat spreader corresponding to each said integrated circuit device in non-contact proximity to said electrically active face so that said integrated circuit device is disposed between said leads and said heat spreader; and   encapsulating said semiconductor device, at least a portion of said heat spreader, and at least a portion of said leads in a molding resin,   wherein   the heat spreader has
 an outer portion in contact with outer lead ends of said leads on opposite sides of the integrated circuit device, the outer portion including a first thinned portion at an end thereof in contact with said outer lead ends, and 
 a central portion having a planar first surface opposite and substantially parallel to said electrically active face, the central portion including a full thickness portion having a planar surface opposite the first surface and a second thinned portion spaced apart from the integrated circuit device and having a lower surface integral with said first surface and an upper surface parallel to said first surface; 
   said encapsulating step includes
 encapsulating all of the second thinned portion and leaving exposed part of the first thinned portion, and 
 leaving exposed a portion of each of said outer lead ends and forming a planar side surface with the exposed portion of an outer lead end, said planar side surface including said exposed part of the first thinned portion; and 
   the package has a bottom surface and a planar sidewall substantially perpendicular thereto, said sidewall including said planar side surface.   
     
     
         2 . A method according to  claim 1  wherein said heat spreader is in a non-planar relationship with respect to a plurality of tie bars and said plurality of tie bars are supported by said package features. 
     
     
         3 . A method according to  claim 2  wherein said heat spreader is completely encapsulated within said molding resin. 
     
     
         4 . A method according to  claim 2  wherein a surface of said heat spreader is exposed and planar with a surface of said molding resin. 
     
     
         5 . A method according to  claim 4  wherein said heat spreader is selected from the group consisting of copper, aluminum, copper-base alloys, and aluminum base alloys. 
     
     
         6 . A method according to  claim 5  further comprising the step of coating said heat spreader prior to encapsulation with molding resin. 
     
     
         7 . A method according to  claim 6  wherein said heat spreader is selected to be an aluminum base alloy and said coating step is black anodization. 
     
     
         8 . A method according to  claim 6  wherein said heat spreader is selected to be a copper-base alloy and said coating step includes applying a coating of nickel. 
     
     
         9 . A method according to  claim 2  further comprising the step of bonding said tie bars to said features. 
     
     
         10 . A method according to  claim 9  wherein said features include a die pad disposed within said central aperture and die pad tie bars extending outwardly from said die pad wherein said heat spreader tie bars are adhesively bonded to at least one of said leads and said die pad tie bars. 
     
     
         11 . A method according to  claim 10 , wherein said heat spreader tie bars are adhesively bonded to at least one of said leads and said die pad tie bars using at least one of an epoxy and a conductive tape. 
     
     
         12 . A method according to  claim 10  further comprising the step of bonding a non-electrically active face of said integrated circuit device to said die pad and electrically interconnecting an electrically active face of said integrated circuit device to said leads by wire bonds or TAB bonds. 
     
     
         13 . A method according to  claim 9  wherein said electrically active face of said semiconductor device is directly bonded to said leads by flip chip bonding. 
     
     
         14 . A method according to  claim 13  wherein a thermally conductive polymer contacts both said electrically inactive face of said integrated circuit device and said heat spreader. 
     
     
         15 . A method according to  claim 9  wherein said heat spreader tie bars interconnect to adjoining heat spreader tie bars to form a heat spreader array. 
     
     
         16 . A method according to  claim 15  wherein said step of encapsulating in molding resin occurs after singulation of said heat spreader tie bars. 
     
     
         17 . A method according to  claim 15  wherein said step of encapsulating in molding resin occurs before singulation of said heat spreader tie bars. 
     
     
         18 . A method according to  claim 15  wherein said heat spreader tie bars have a reduced thickness portion to facilitate singulation. 
     
     
         19 . A semiconductor package comprising:
 a plurality of leads having inner ends and outer ends disposed about a centrally disposed aperture;   an integrated circuit device spanning said aperture and having an electrically active face directly bonded to said inner ends of said plurality of leads by a solder;   a heat spreader in non-contact proximity to an electrically inactive face of said integrated circuit device, whereby said integrated circuit device is disposed between said plurality of leads and said heat spreader; and   a molding resin encapsulating said integrated circuit device, at least a portion of said heat spreader, and at least a portion of said outer ends, leaving exposed a portion of each of said outer lead ends and forming a planar side surface with the exposed portion of an outer lead end,   wherein   the heat spreader has
 an outer portion in contact with the outer ends of leads on opposite sides of the die pad, the outer portion including a first thinned portion at an end thereof in contact with said outer lead ends, and 
 a central portion having a planar first surface opposite and substantially parallel to said electrically inactive face, the central portion including a full thickness portion having a planar surface opposite the first surface, and a second thinned portion spaced apart from the die pad and having a lower surface integral with said first surface and an upper surface parallel to said first surface; 
   said molding resin encapsulates all of the second thinned portion and leaves exposed part of the first thinned portion, said planar side surface including said exposed part of the first thinned portion; and   the package has a bottom surface and a planar sidewall substantially perpendicular thereto, said sidewall including said planar side surface.   
     
     
         20 . A semiconductor package according to  claim 19  wherein said heat spreader is selected from the group consisting of copper, aluminum, copper-base alloys, and aluminum-base alloys. 
     
     
         21 . A semiconductor package according to  claim 20  wherein said heat spreader further comprises a coating, which is added to said heat spreader prior to encapsulation with said molding resin. 
     
     
         22 . A semiconductor package according to  claim 20  wherein said heat spreader is an aluminum-base alloy coated with a black anodization and a surface of said heat spreader is exposed in planar relationship with said molding resin. 
     
     
         23 . A semiconductor package according to  claim 20  wherein a thermally conductive polymer is disposed between said electrically inactive face and said heat spreader. 
     
     
         24 . A semiconductor package according to  claim 20  wherein a die pad is disposed within said aperture and said integrated circuit device is directly bonded to said die pad. 
     
     
         25 . A semiconductor package according to  claim 19  further comprising an adhesive for joining said heat spreader with at least a portion of said plurality of leads. 
     
     
         26 . A semiconductor package according to  claim 25 , wherein said adhesive is one of an epoxy and a conductive tape.