Method of improving parallelism of a die to package using a modified lead frame

Abstract

A structure and method are provided to allow a die to be packaged more uniformly and in parallel with a package by utilizing a lead frame having at least one cavity within the lead frame, thereby allowing excess die-attach epoxy can flow into the cavity or cavities and reducing the amount of contact surface area between the die and lead frame.

We claim:  
     
         1 . A structure for packaging a die, comprising: 
 a lead frame having an upper surface and at least one cavity formed through said upper surface, said at least one cavity underlying a portion of said die for receiving excess die-attach epoxy when said die is adhered to said lead frame.    
     
     
         2 . The structure of    claim 1   , wherein said at least one cavity extends completely through said lead frame.  
     
     
         3 . The structure of    claim 1   , wherein said at least one cavity partially extends into said lead frame.  
     
     
         4 . The structure of    claim 1   , wherein said lead frame comprises at least two cavities to form an array of said cavities.  
     
     
         5 . The structure of    claim 4   , wherein a die-attach epoxy is only deposited over said array.  
     
     
         6 . The structure of    claim 4   , wherein at least one dimension of said array is slightly larger than at least one dimension of said die.  
     
     
         7 . The structure of    claim 4   , wherein said cavities are rectangular shaped.  
     
     
         8 . The structure of    claim 1   , wherein said lead frame comprises a single cavity.  
     
     
         9 . The structure of    claim 8   , wherein said cavity is circular shaped.  
     
     
         10 . The structure of    claim 8   , wherein said cavity is oval shaped.  
     
     
         11 . The structure of    claim 8   , wherein at least one dimension of said cavity is slightly smaller than at least one dimension of said die.  
     
     
         12 . A method for packaging a die, comprising: 
 forming at least one cavity formed through the upper surface of a lead frame;    depositing epoxy over said at least one cavity; and    placing said die over said epoxy and the upper surface of said lead frame, wherein excess amounts of said epoxy flow into said at least one cavity.    
     
     
         13 . The method of    claim 12   , wherein said epoxy is deposited so that a portion of said epoxy is above the upper surface of said lead frame.  
     
     
         14 . The method of    claim 12   , wherein said at least one cavity extends completely through said lead frame.  
     
     
         15 . The method of    claim 12   , wherein said at least one cavity partially extends into said lead frame.  
     
     
         16 . The method of    claim 12   , wherein said forming forms at least two cavities to create an array of said cavities.  
     
     
         17 . The method of    claim 16   , wherein said die-attach epoxy is only deposited over said array.  
     
     
         18 . The method of    claim 16   , wherein at least one dimension of said array is slightly larger than at least one dimension of said die.  
     
     
         19 . The method of    claim 16   , wherein said cavities are rectangular shaped.  
     
     
         20 . The method of    claim 12   , wherein said forming forms a single cavity.  
     
     
         21 . The method of    claim 20   , wherein said cavity is circular shaped.  
     
     
         22 . The method of    claim 20   , wherein said cavity is oval shaped.  
     
     
         23 . The method of    claim 20   , wherein at least one dimension of said cavity is slightly smaller than at least one dimension of said die.