Appeal No. 2003-1246
Application 08/393,617
preferable to PbO when the glass compositions are employed as
resistive coatings in cathode ray tubes,3 Weaver does not
describe the function of PbO and ZnO when the glass compositions
are employed as solder glasses or identify the property of PbO
and ZnO which accounts for their equivalence in Weaver's solder
glasses. Likewise, Snell fails to explain the function of PbO in
his solder glass compositions or identify the property of PbO
that is responsible for that function. Furthermore, in view of
the considerable differences between Weaver's and Snell's solder
glass compositions (i.e., Weaver's solder glasses contain at
least 50% by weight of V2O5 and P2O5 and no more than 15% by
weight of Sb2O3 and/or B2O3, whereas Snell's solder glasses
contain at least about 95% by weight of Sb2O3 and B2O3 and no V2O5
or P2O5), it is unreasonable to assume (a) that PbO plays the
same role in Weaver's and Snell's solder glass compositions or
(b) that ZnO can be substituted for PbO in Snell's solder glass
compositions. Weaver does not suggest that the similar effect of
PbO and ZnO in his solder glass compositions is independent of
the identity and amount of the other components.
3 ZnO is more water soluble than PbO (col. 5, ll. 35-39)
and is not subject to being reduced into lead and oxides of
carbon when in contact with an Aquadag coating (col. 6, ll.
12-18).
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