US Patent 9059185 Copper leadframe finish for copper wire bonding

A semiconductor device (100) includes a leadframe having a chip pad (110) and a lead (111) with a first end (112) proximate to the pad and a second end (113) remote from the pad, the leadframe having a base metal (120) including copper and a stack of a plated first layer (121) of nickel in contact with the base metal and a plated second layer (122) of a noble metal in contact with the nickel layer, the second lead end free of the noble metal. Further included is a copper wire (104) having a ball bond (104a) on a semiconductor chip (101) attached to the chip pad, and a stitch bond (104b) on the proximate lead end, the stitch bond penetrating the second layer; furthermore a packaging compound (130) encapsulating the chip, the wire, and the first end of the lead, the compound leaving the second end of the lead un-encapsulated; and the unencapsulated second lead end covered with a plated third layer (123) of solder.