Appeal No. 95-0638
Application 08/011,094
obviousness. Note In re Oetiker, 977 F.2d 1443, 1445, 24 USPQ2d
1443, 1444 (Fed. Cir. 1992).
Admitted prior art Figure 13 is the primary reference for
each of the rejections. Figure 13 shows a fragmentary sectional
view of a typical substrate 24 and base assembly 34 upon which a
power transistor package 20 is placed. The metallized substrate
28 in Figure 13 is coated on both sides by a molymanganese (MoMn)
coating. This coating is selected for its adhesive and thermal
characteristics. The examiner asserts that prior art Figure 13
shows all the claimed features except for the “thick copper layer
bonded to a thin nickel layer for spreading heat from the
transistors to the plate” [answer, page 3]. The difference
between Figure 13 and the claimed invention which is argued to be
critical is that the MoMn coating of Figure 13 has been replaced
in the invention by a copper layer of a particular thickness
which is bonded to the ceramic substrate.
Kurihara ’733 discloses an insulated semiconductor device
in which a ceramic substrate 2 has copper layers 203 and 204 on
both sides each having a thickness of about 100 mm [translation,
page 11]. Kurihara ’899 also discloses an insulated
semiconductor device in which a ceramic substrate 2 is placed
between a composite metal plate 3 and a metal support 1. The
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