Appeal 2007-1772
Application 10/672,750
different sizes such that the use of an overhang or offset (shingle stack)
stacking arrangement would have been a recognized obvious option to one
of ordinary skill in the art in forming the stacked die product of Pai? We
answer this question in the affirmative.
We recognize that Huang is directed to a dual-chip integrated circuit
package wherein the chips are located on opposing sides of a metal
leadframe substrate (see, e.g., Huang, Fig. 2, Fig. 10) whereas here the
claimed integrated circuit stacks, as well as Pai’s stacks involve chips (die)
that are stacked together on the same side of a substrate. Nonetheless,
Huang clearly evinces that packageable integrated circuit chips come in
different sizes and are designed for different purposes or functions that can
be used in combination in an integrated circuit (col. 2, ll. 12-15 and 44-47).
From the combined teachings of these references, one of ordinary skill
in the art would have recognized the obviousness of using the stacking
arrangement of Pai for stacking chips (die) of differing sizes, including chips
having differing diameters such that an overhang or “shingle stack” stacking
arrangement would have commended itself as an available option to an
ordinarily skilled artisan faced with the task of stacking die of differing sizes
for forming integrated circuit packages. Indeed, Appellants acknowledge a
considerable skill level is expected of one of ordinary skill in this art
(Specification 5: ll. 8-17).
In light of the above and for reasons as set forth in the Answer,
Appellants’ arguments concerning the combinability of Pai and Huang for
teaching/suggesting the overhang of dies stacked in an integrated circuit
package are not persuasive (Br. 19-20; Reply Br. 6). In this regard, we note
that the test for obviousness is not whether the features of a secondary
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