Locking dual leadframe for flip chip on leadframe packages

Abstract

A method of assembling a flip chip on a leadframe package. A locking dual leadframe (LDLF) includes a top metal frame portion including protruding features and a die pad and a bottom metal frame portion having apertures positioned lateral to the die pad. The protruding features and apertures are similarly sized and alignable. A flipped integrated circuit (IC) die having a bottomside and a topside including circuitry connected to bond pads having solder balls on the bond pads is mounted with its topside onto the top metal frame portion. The top metal frame portion is aligned to the bottom metal frame portion so that the protruding features are aligned to the apertures. The bottomside of the IC die is pressed with respect to a top surface of the bottom frame portion, wherein the protruding features penetrate into the apertures.

1 . A method of assembling a flip chip on a leadframe package, comprising:
 providing a locking dual leadframe (LDLF) including a top metal frame portion including protruding features and a die pad and a bottom metal frame portion having apertures positioned lateral to an area of said die pad, said protruding features and said apertures being similarly sized and alignable;   mounting a flipped integrated circuit (IC) die having a bottomside and a topside including circuitry connected to bond pads having solder balls on said bond pads with said topside onto said top metal frame portion;   aligning said top metal frame portion to said bottom metal frame portion so that said protruding features are aligned to said apertures, and   pressing said bottomside of said IC die with respect to a top surface of said bottom metal frame portion, wherein said protruding features penetrate into said apertures.   
     
     
         2 . The method of  claim 1 , wherein said protruding features are an integral component of said top metal frame portion. 
     
     
         3 . The method of  claim 1 , wherein said mounting takes place before said aligning and said pressing, and said bottom metal frame portion includes die attach material on said top surface before said pressing. 
     
     
         4 . The method of  claim 1 , wherein said protruding features are button shaped and include necking and said apertures comprise a circular hole. 
     
     
         5 . The method of  claim 1 , wherein said protruding features are U shaped and include side necking and said apertures comprise a rectangular hole. 
     
     
         6 . The method of  claim 1 , wherein said protruding features include a linear frame and said apertures comprise a longitudinal hole, further comprising bending a protruding end of said linear frame onto said bottom metal frame portion after said pressing. 
     
     
         7 . The method of  claim 1 , wherein said top metal frame portion and said bottom metal frame portion are parts of leadframe sheets, further comprising molding after said pressing and then singulating to form a plurality of said flip chip on leadframe packages, wherein said singulating removes said protruding features and said apertures. 
     
     
         8 . The method of  claim 1 , wherein said top metal frame portion includes a plurality of leads. 
     
     
         9 . The method of  claim 1 , wherein said top metal frame portion and said bottom metal frame portion both include pilot holes for said aligning. 
     
     
         10 . A locking dual leadframe (LDLF) combination, comprising:
 a top metal frame portion including protruding features and a die pad, and   a bottom metal frame portion having apertures positioned lateral to an area of said die pad and sized and alignable so that when said top metal frame portion is pressed with respect to a top surface of said bottom metal frame portion said protruding features penetrate into said apertures.   
     
     
         11 . The LDLF combination of  claim 10 , wherein said protruding features are an integral component of said top metal frame portion. 
     
     
         12 . The LDLF combination of  claim 10 , wherein said protruding features are button shaped and include necking and said apertures comprise a circular hole. 
     
     
         13 . The LDLF combination of  claim 10 , wherein said protruding features are U shaped and include side necking and said apertures comprise a rectangular hole. 
     
     
         14 . The LDLF combination of  claim 10 , wherein said protruding features include a linear frame and said apertures comprise a longitudinal hole. 
     
     
         15 . The LDLF combination of  claim 10 , wherein said top metal frame portion includes a plurality of leads. 
     
     
         16 . The LDLF combination of  claim 10 , wherein said top metal frame portion and said bottom metal frame portion both include pilot holes for aligning said top metal frame portion to said bottom metal frame portion.