Active solid-state devices (e.g. – transistors – solid-state diode – Lead frame
Reexamination Certificate
2011-01-18
2011-01-18
Pert, Evan (Department: 2826)
Active solid-state devices (e.g., transistors, solid-state diode
Lead frame
C257SE23054, C257SE23124
Reexamination Certificate
active
07872336
ABSTRACT:
A leadframe with a structure made of a base metal (105), wherein the structure has a plurality of surfaces. On each of these surfaces are metal layers in a stack adherent to the base metal. The stack comprises a nickel layer (201) in contact with the base metal, a palladium layer (202) in contact with the nickel layer, and an outermost tin layer (203) in contact with the palladium layer. In terms of preferred layer thicknesses, the nickel layer is between about 0.5 and 2.0 μm thick, the palladium layer between about 5 and 150 nm thick, and the tin layer less than about 5 nm thick, preferably about 3 nm. At this thinness, the tin has no capability of forming whiskers, but offers superb adhesion to polymeric encapsulation materials, improved characteristics for reliable stitch bonding as well as affinity to reflow metals (solders).
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Brady III Wade J.
Pert Evan
Soderholm Krista
Telecky , Jr. Frederick J.
Texas Instruments Incorporated
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