Appeal No. 1997-2834
Application No. 08/190,729
As pointed out by the appellant, the problems to be
solved and/or the solutions to the problems in the Levine
patents are different from that of the present invention. We
do not find any teaching in the relied upon prior art to show
that a corrosion problem even existed in prior art lead
frames.
Specifically, Levine ‘067 is concerned with solving the
problem of corrosion in a sealing lid for semiconductor
packages in which the sealing lid comprises a metal substrate
(e.g., an iron alloy), a first layer of nickel, a first layer
of gold, a second layer of nickel, and a second layer of gold
(column 1, line 58 to column 2, line 6). Levine ‘067 solves
the problem of corrosion by forming a base layer of a metal
(e.g., gold) having an electromotive potential higher than the
metal substrate, an intermediate layer of a metal (e.g.,
nickel) having an electromotive potential substantially lower
than the electromotive potential of the base layer metal, and
a cover layer having a metal with an electromotive potential
which is high with respect to the base layer (column 2, lines
15-31). Although Levine ‘067 teaches that the intermediate
layer can have an electromotive potential “somewhat similar to
that of” the metal substrate (column 3, lines 41-46), there is
no teaching or suggestion in Levine ‘067 of an intermediate
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