Multi-part lead frame with dissimilar materials

Abstract

A multi-part lead frame semiconductor device assembly is disclosed including a die bonded to a die paddle. A second lead frame including leads is superimposed and bonded onto the first lead frame. Also disclosed is a method for fabricating the multi-part lead frame semiconductor device assembly which utilizes equipment designed for single lead frame processing. If desired, the materials for the multi-part lead frame may be dissimilar.

1 . A semiconductor device assembly comprising: 
 a semiconductor device including an active surface having at least one bond pad formed thereon;    a die paddle having the semiconductor device attached thereto, the die paddle substantially formed of a first material, the die paddle formed on a first level;    a lead frame including at least two carriers and a plurality of leads, each carrier of the at least two carriers having an attachment tab-receiving portion, the lead frame substantially formed of a second material different than the first material of the die paddle, wherein at least one lead of the plurality of leads extends over a semiconductor device attached to the die paddle, does not extend over a semiconductor device attached to the die paddle, overlaps the die paddle, or terminates adjacent the die paddle, the lead frame formed on a second level; and    at least one interconnection between at least one lead of the plurality of leads of the lead frame and the at least one bond pad of the semiconductor device.    
   
   
       2 . The semiconductor device assembly according to  claim 1 , wherein a heat conductivity of the first material of the die paddle is different than that of the second material of the lead frame.  
   
   
       3 . The semiconductor device assembly according to  claim 1 , wherein an electrical conductivity of the second material of the lead frame is different than that of the first material of the die paddle.  
   
   
       4 . The semiconductor device assembly according to  claim 1 , wherein an electrical conductivity of the second material of the lead frame is greater than an electrical conductivity of the die paddle.  
   
   
       5 . The semiconductor device assembly according to  claim 1 , further including an insulating film, the insulating film covering a portion of the active surface of the semiconductor device.  
   
   
       6 . The semiconductor device assembly according to  claim 1 , wherein the first material of the die paddle is selected from the group comprising alloy 42, copper alloy, aluminum alloy, silver alloy, copper-clad Invar, copper-clad molybdenum, ceramic compounds, plastic compounds, glass epoxy-based compounds, and reinforced organic compounds.  
   
   
       7 . The semiconductor device assembly according to  claim 1 , wherein the second material of the lead frame is selected from the group comprising alloy 42, copper alloy, aluminum alloy, and silver alloy.  
   
   
       8 . The semiconductor device assembly according to  claim 1 , wherein the at least one interconnection includes a wire bond.  
   
   
       9 . A semiconductor device assembly having a semiconductor die assembly comprising: 
 a semiconductor die including an active surface having at least one bond pad formed thereon;    a separately formed die paddle onto which said semiconductor die is attached;    a separately formed lead frame including at least two carriers, each carrier having an attachment tab receiving portion, said lead frame having plurality of leads, the plurality of leads each having a length terminating adjacent said semiconductor device; and    at least one interconnection between at least one lead of said plurality of leads of said separately formed lead frame and said at least one bond pad of said semiconductor die attached to said separately formed die paddle.    
   
   
       10 . A semiconductor device assembly according to  claim 9 , wherein the heat conductivity of said die paddle is different than that of said lead frame.  
   
   
       11 . A semiconductor device assembly according to  claim 9 , wherein the material of said die paddle is different than the material of said lead frame.  
   
   
       12 . A semiconductor device assembly according to  claim 9 , wherein the electrical conductivity of the material of said lead frame is different than that of the material of said die paddle.  
   
   
       13 . A semiconductor device assembly according to  claim 9 , wherein the electrical conductivity of the material of said lead frame is greater than that of the material of said tie bars.  
   
   
       14 . A semiconductor device assembly according to  claim 9 , wherein the material of said die paddle is selected from the group comprising alloy 42, copper alloy, aluminum alloy, silver alloy, copper-clad Invar, copper-clad molybdenum, ceramic compounds, plastic compounds, glass epoxy based compounds, and reinforced organic compounds.  
   
   
       15 . A semiconductor device assembly according to  claim 9 , wherein the material of said lead frame is selected from the group of alloy 42, copper alloy, aluminum alloy, and silver alloy.  
   
   
       16 . A semiconductor device assembly according to  claim 9 , wherein the interconnection includes a wire bond.  
   
   
       17 . A semiconductor die assembly comprising: 
 a semiconductor die including an active surface having at least one bond pad formed thereon;    a die paddle of a first material onto which said semiconductor die is attached;    at least one tie bar connected to said die paddle, the tie bar including an attachment tab thereon;    a lead frame of a second material including carriers, each carrier having an attachment tab receiving portion attached to a portion of said attachment tab of a tie bar, and a plurality of leads, each lead including an inner lead portion and an outer lead portion; and    at least one interconnection between at least one said inner lead portion of said lead frame and said at least one bond pad of said semiconductor die.    
   
   
       18 . A semiconductor die assembly according to  claim 17 , wherein said inner lead portion of at least one of the leads extends over said active surface of said semiconductor die.  
   
   
       19 . A semiconductor die assembly according to  claim 17 , wherein said inner lead portion of at least one of the leads does not extend over said active surface of said semiconductor die.  
   
   
       20 . A semiconductor die assembly according to  claim 17 , wherein said inner lead portion of at least one of the leads overlaps said die paddle.  
   
   
       21 . A semiconductor die assembly according to  claim 17 , wherein said lead frame and said tie bar are made of different materials.  
   
   
       22 . A semiconductor die assembly according to  claim 17 , wherein the heat conductivity of the first material of said die paddle is different than that of the second material of said lead frame.  
   
   
       23 . A semiconductor die assembly according to  claim 17 , wherein the first material of said die paddle is different than the second material of said lead frame.  
   
   
       24 . A semiconductor die assembly according to  claim 17 , wherein the electrical conductivity of the second material of said lead frame is different than that of the first material of said die paddle.  
   
   
       25 . A semiconductor die assembly according to  claim 17 , wherein the electrical conductivity of the second material of said lead frame is different than that of the material of said tie bar.  
   
   
       26 . A semiconductor die assembly according to  claim 17 , further including an insulating film, said insulating film covering a portion of said active surface of said semiconductor die.  
   
   
       27 . A semiconductor die assembly according to  claim 17 , wherein said interconnection includes a wire bond.