Thin tin preplated semiconductor leadframes
AssigneeTexas Instruments Incorporated
InventorsDonald C. Abbott, Douglas W. Romm
Life of this patent
Estimating the term…
Abstract
A leadframe for use with integrated circuit chips comprising a base metal having a plated layer of nickel fully covering the base metal and a plated layer of pure tin, only </=0.5 μm thick, on the nickel layer, selectively covering areas of the leadframe intended for attachment to other parts. For devices with gull-wing-shaped leads, these pre-plated tin areas cover only the external lead surface intended to face an outside part, and the lead edges. Further, a plated layer of palladium on the nickel layer selectively covers areas of the leadframe intended for bonding wire attachment.
Claims16
A leadframe for use in the assembly of integrated circuit chips, comprising:
- a base metal structure having an adherent layer comprising nickel covering said base metal;
- an adherent layer comprising palladium, or silver on said nickel layer, selectively covering areas of said leadframe suitable for bonding wire attachment;
- and
- an adherent layer of pure tin, less than or equal 0.5 μm thick, on said nickel layer, selectively covering areas of said leadframe suitable for parts attachment.
A leadframe for use with integrated circuit chips comprising:
- a base metal structure having a plated layer of nickel fully covering said base metal;
- an plated layer comprising palladium, or silver on said nickel layer, selectively covering areas of said leadframe suitable for bonding wire attachment;
- and
- a plated layer of pure tin, less than or equal 0.5 μm thick, on said nickel layer, selectively covering areas of said leadframe suitable for parts attachment.
A semiconductor device comprising:
- a leadframe comprising a chip mount pad for an integrated circuit chip and a plurality of lead segments, each having a first end near said mount pad and a second end remote from said mount pad;
- said leadframe having a surface layer of nickel;
- said leadframe further having a layer of palladium on said nickel layer, selectively covering said first ends of said lead segments in a thickness suitable for bonding wire attachment;
- an integrated circuit chip attached to said mount pad;
- bonding wires interconnecting said chip and said first ends of said lead segments;
- encapsulation material surrounding said chip, bonding wires and said first ends of said lead segments, while leaving said second ends of said lead segments exposed;
- and
- a layer of pure tin, less than or equal 0.5 μm thick, on said nickel layer, selectively covering said second ends of said lead segments in a distribution suitable for parts attachment.
Dependencies are inferred from the claim text.