Appeal No. 1997-0330
Application 08/493,758
present in concentrations exceeding its solubility
product, the claimed invention patentably distinguishes
over Kirman.
From our review of Kirman, we do not find that
Kirman places any limitation on the concentration of
fluoride complex in the plating bath. When discussing
the fluoride component in the plating bath, Kirman merely
requires a source of supply, leaving open the amount.
See col. 5, lines 30-42. Nothing critical is indicated
for the fluoride concentration. Kirman places
limitations on, for example, the concentration of
stannous ions (col. 3, lines 3-20) but suggests no upper
limit for the fluoride ions. Although Kirman (col. 5)
does disclose preferable ranges for fluoride ion
concentration, depending on the type of tin alloy being
deposited, higher concentrations are not precluded. In
fact, with respect to coating pure tin, Kirman (col. 4,
lines 67-68) specifically states that the plating bath
can contain "greater than 1.0 g/l fluoride ions, or
fluoride containing ions, or mixtures thereof".
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