Protective coating combination for lead frames

Details Protective coating combination for lead frames Protective coating combination for lead frames

1995-04-27

1997-07-22

Crane, Sara W.

Active solid-state devices (e.g., transistors, solid-state diode

Lead frame

Of specified material other than copper

257736, 257748, H01L 23495

Patent

active

056506619

ABSTRACT:
A lead frame for a semiconductor device includes a base layer which is coated by a protective coating. The protective coating includes a layer of nickel, over which is coated a layer of copper. The layer of copper is coated by a layer of silver over which is coated a layer of palladium. Protective coatings constructed in this way are bondable, solderable, oxidation resistant, corrosion resistant, free of lead (Pb), resistant to high temperatures, cost effective, and cosmetically acceptable. It is also possible to use a layer of tin or a tin alloy in place of the silver layer. It is possible to omit the nickel layer if the lead base layer is made of a ferrous material.

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Donald C. Abbott et al., Palladium as a Lead Finish for Surface Mount Integrated Circuit Packages; Texas Instruments Incorporated, Dallas, Texas, frm IEPC Proceedings, Sep. 1990.

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