Appeal No. 2002-2080
Application 09/358,484
consistent with the written description in the specification. We find that one of ordinary skill in
this art would have found the following in the written description of appellants’ specification.
Appellants disclose an “aluminum nitride ceramic comprising a sintered article consisting mainly
of aluminum nitride and having a thermal conductivity higher than 100 W/m.K at room
temperature and a smooth dense surface layer formed on a surface of the sintered article” which
has the surface roughness and defect characteristics specified in the appealed claims (page 2, line
22, to page 3, line 1; see also page 3, lines 4-9) . Appellants further disclose that “[p]referably,
the surface layer (2) [of the aluminum nitride ceramic of FIG. 1] consists mainly of . . . oxide
glass,” wherein “[a]t least the first oxide glass layer deposited directly on a surface of the sintered
article is preferably made of oxide glass which do not contain Na, K, Rb and Pb” (page 3, lines
12-13 and 19-21). The disclosed process is “characterized by the steps of applying a paste for
said surface layer onto a surface of a sintered article . . . of aluminum nitride and sintering’ (page
3, line 24, to page 4, line 2), wherein “[t]he surface layer [of the aluminum nitride ceramic] can
be prepared by repeating two steps of applying an oxide glass paste onto a sintered article of
[aluminum nitride] and sintering” (page 4, lines 6-8). The paste of oxide glass can be applied by
“screen printing techniques” (e.g., page 13, lines 13-14).
It is clearly stated in the specification that “[p]referably a surface of the sintered article of
aluminum nitride is oxidized before the paste of oxide glass is coated” (id., lines 13-15), and that
“[t]he content of [aluminum nitride] in the sintered article of [aluminum nitride] is preferably
more than 80% by weight” and can contain other components (page 4, line 16, to page 5, line
18). In describing the oxidation surface treatment, it is disclosed that “an oxide layer (alumina
layer)” can be formed (page 8, line 5). The nature of the oxidized surface of the aluminum
nitride article was not reported in Examples 13 and 14.
The purpose of forming the aluminum nitride ceramic in the manner disclosed is “to
improve thermal conductivity and to improve surface smoothness” so that the ceramic article can
serve as, for example “a substrate for integrated circuits” (pages 1-2).
We find in the written description of appellants’ specification no definition or other
limitation with respect to “a surface” of “a sintered article of aluminum nitride” onto which at
least one layer of paste of oxide glass is “directly” applied, either with respect to the character of
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