Semiconductor devices and electrical parts manufacturing using metal coated wires

Abstract

The device of this invention includes a semiconductor die attached to a bare copper lead frame and electrically coupled to a lead by a metal wire coated with a metallic material. The device would function similarly to devices where the lead frames were coated with other metallic materials, but at lower costs because instead of plating the lead frame the wire is plated. The wire can be either gold or aluminum. When the wire is gold, the coating may be silver or other suitable metallic materials. When the wire is aluminum, the coating may be nickel, palladium, or other suitable metals.

1 . A method of manufacturing a semiconductor device comprising the steps of:
 providing a semiconductor die having top and bottom surfaces, said die having one or more bond pads on the top surface for connecting the die to leads of a lead frame, said bond pads comprising a first metal;   providing bond wires comprising a core of the first metal and a coating of a second metal;   providing a lead frame with a die attach pad and a plurality of leads, said lead frame and said leads comprising a third metal;   attaching the semiconductor die to the die attach pad of the lead frame;   attaching one end of each coated bond wire to one of the bond pads on the semiconductor die and attaching the other end of each coated bond wire coated wire to a lead of the lead frame, wherein the one end of the coated bond wire forms a metallurgical bond of the first and second metals with the bond pads on the semiconductor die and the other end of the coated wire forms a metallurgical bond of the first, second and third metals on the lead frame; and   packaging the lead frame and semiconductor die.   
     
     
         2 . The method of  claim 1  wherein the third of the lead frame does not form a metallurgical bond with only the first metal. 
     
     
         3 . The method of  claim 1  wherein the first metal is aluminum, the second metal is nickel the third metal is copper. 
     
     
         4 . The method of  claim 1  wherein the third metal is bare copper. 
     
     
         5 . The method of  claim 1 , wherein the first metal of the wire includes aluminum or aluminum alloy. 
     
     
         6 . The method of  claim 1 , wherein the first metal includes gold or gold alloy. 
     
     
         7 . The method of  claim 6 , wherein the second metal includes silver. 
     
     
         8 . The method of  claim 1 , wherein the second metal is selected from the group consisting of nickel or palladium. 
     
     
         9 . The method of  claim 1 , wherein the method of attachment includes thermosonic bonding. 
     
     
         10 . The method of  claim 1 , wherein the bonding step is ultrasonic bonding. 
     
     
         11 . A method of manufacturing a semiconductor device comprising the steps of:
 providing a semiconductor die having top and bottom surfaces, said die having one or more bond pads on the top surface for connecting the die to leads of a lead frame, said bond pads comprising aluminum or aluminum alloy;   providing bond wires comprising a core of aluminum or aluminum alloy and a coating of a nickel;   providing a lead frame with a die attach pad and a plurality of leads, said lead frame and said leads comprising bare copper;   attaching the semiconductor die to the die attach pad of the lead frame;   attaching one end of each coated bond wire to one of the bond pads on the semiconductor die and attaching the other end of each coated bond wire coated wire to a lead of the lead frame, wherein on the bond pads on the semiconductor die the one end of the coated bond wire forms a metallurgical bond of nickel and aluminum or nickel and aluminum alloy and on the lead frame the other end of the coated wire forms a metallurgical bond of nickel, copper and aluminum or nickel, copper and aluminum alloy; and   packaging the lead frame and semiconductor die.   
     
     
         12 . The method of  claim 11  wherein the method of attachment includes thermosonic bonding. 
     
     
         13 . The method of  claim 11  wherein the bonding step is ultrasonic bonding. 
     
     
         14 . A semiconductor device comprising:
 a semiconductor die having top and bottom surfaces, said die having one or more bond pads on the top surface for connecting the die to leads of a lead frame, said bond pads comprising a first metal;   bond wires comprising a core of the first metal and a coating of a second metal;   a lead frame with a die attach pad and a plurality of leads, said lead frame and said leads comprising a third metal;   the semiconductor die attached to the die attach pad of the lead frame; and   each coated bond wire having one end attached to one of the bond pads on the semiconductor die and attaching the other end of each coated bond wire coated wire attached to a lead of the lead frame, wherein the one end of the coated bond wire forms a metallurgical bond of the first and second metals with the bond pads on the semiconductor die and the other end of the coated wire forms a metallurgical bond of the first, second and third metals on the lead frame.   
     
     
         15 . The semiconductor device of  claim 14  wherein the third of the lead frame does not form a metallurgical bond with only the first metal. 
     
     
         16 . The semiconductor device of  claim 14  wherein the first metal is aluminum, the second metal is nickel the third metal is copper. 
     
     
         17 . The semiconductor device of  claim 14  wherein the third metal is bare copper. 
     
     
         18 . The semiconductor device of  claim 1 , wherein the first metal of the wire includes aluminum or aluminum alloy. 
     
     
         19 . The semiconductor device of  claim 14 , wherein the first metal includes gold or gold alloy. 
     
     
         20 . The semiconductor device of  claim 19 , wherein the second metal includes silver. 
     
     
         21 . The semiconductor device of  claim 14 , wherein the second metal is selected from the group consisting of nickel or palladium.