Ex parte LIU

Board of Patent Appeals and Interferences

Mar 27, 1998

08150742 (B.P.A.I. Mar. 27, 1998)

Application for patent filed November 12, 1993. According1
to the appellant, this application is a continuation of
Application 07/891,315, filed May 29, 1992.
1
THIS OPINION WAS NOT WRITTEN FOR PUBLICATION
The opinion in support of the decision being entered today (1)
was not written for publication in a law journal and (2) is not
binding precedent of the Board.
Paper No. 18
UNITED STATES PATENT AND TRADEMARK OFFICE
_____________
BEFORE THE BOARD OF PATENT APPEALS
AND INTERFERENCES
_____________
Ex parte WILLIAM UEI-CHUNG LIU

_____________
Appeal No. 96-0019
Application 08/150,7421
______________
ON BRIEF
_______________
Before KRASS, JERRY SMITH and BARRETT, Administrative Patent
Judges.
JERRY SMITH, Administrative Patent Judge.
DECISION ON APPEAL
Appeal No. 96-0019
Application 08/150,742
2
This is a decision on the appeal under 35 U.S.C. § 134
from the examiner's rejection of claims 24-28. Claims 1-23 have
been cancelled. Claims 29-37 have been indicated by the examiner
as being allowable.
The claimed invention pertains to a transistor having a
plurality of active regions arranged around a central active
region. The spacing between active regions is changed as the
active regions move away from the central region. The change in
spacing is said to modify the temperature distribution at the
transistor junctions so that a more uniform temperature can be
maintained across the entire transistor.
Representative claim 24 is reproduced as follows:
24. A transistor comprising a plurality of sets of
active regions arranged about a central active region, wherein at
least two of said sets lie at unequal intervals from said central
active region, and further wherein the interval between a set
nearest said central region and said central region is
approximately 50% larger than the interval between said nearest
set and a set next-nearest to said central active region.
The examiner relies on the following references:
Fukino 3,704,398 Nov. 28, 1972
Alderstein 4,939,562 July 03, 1990
Claims 24-28 stand rejected under 35 U.S.C. § 103. As
evidence of obviousness the examiner offers Fukino in view of
Alderstein.
Appeal No. 96-0019
Application 08/150,742
3
Rather than repeat the arguments of appellant or the
examiner, we make reference to the brief and the answer for the
respective details thereof.
OPINION
We have carefully considered the subject matter on
appeal, the rejection advanced by the examiner and the evidence
of obviousness relied upon by the examiner as support for the
rejection. We have, likewise, reviewed and taken into
consideration, in reaching our decision, the appellant’s
arguments set forth in the brief along with the examiner's
rationale in support of the rejection and arguments in rebuttal
set forth in the examiner's answer.
It is our view, after consideration of the record before
us, that the collective evidence relied upon and the level of
skill in the particular art would have suggested to one of
ordinary skill in the art the obviousness of the invention as set
forth in claims 24-28. Accordingly, we affirm.
Appellant has nominally indicated that the claims on
appeal stand or fall together in a single group [brief, page 3].
However, appellant has made separate comments directed to the
dependent claims. The extent of appellant’s arguments is to
Appeal No. 96-0019
Application 08/150,742
4
simply indicate what is recited in the dependent claims without
providing any analysis as to why the added limitations patentably
distinguish over the applied prior art. Simply pointing out what
a claim requires with no attempt to point out how the claim
patentably distinguishes over the prior art does not amount to a
separate argument for patentability. In re Nielson, 816 F.2d
1567, 1572, 2 USPQ2d 1525, 1528 (Fed. Cir. 1987). Since
appellant has failed to appropriately argue the separate
patentability of the dependent claims, these claims will stand or
fall with the independent claim from which they depend. See In
re King, 801 F.2d 1324, 1325, 231 USPQ 136, 137 (Fed. Cir. 1986);
In re Sernaker, 702 F.2d 989, 991, 217 USPQ 1, 3 (Fed. Cir.
1983). Accordingly, we will consider the rejection against claim
24 as representative of all the claims on appeal.
With respect to independent claim 24, the examiner cites
Fukino as a teaching in the same art to solve the same problem
disclosed by appellant. Specifically, Fukino notes that power
transistors of the type disclosed and claimed by appellant
require large emitter and collector junction areas, and the prior
art has addressed this problem by dividing the emitter junction
into a plurality of divided active areas [column 1, lines 19-27].
Fukino also notes that when these emitter areas are spaced
Appeal No. 96-0019
Application 08/150,742
5
equidistantly apart, the temperature distribution across the
active areas is not equal [Id., lines 38-49]. It is the purpose
of Fukino to adjust the interval between adjacent emitter
junction segments so as to create a substantially uniform
junction temperature across the entire transistor.
Although claim 24 does not recite any details regarding
the materials of the transistor, the examiner has cited
Alderstein to demonstrate that a heterojunction power transistor
of the type disclosed by appellant was known in the art. In
other words, it is the position of the examiner that Alderstein
teaches the prior art transistor before appellant’s modification
in which the emitter junctions are located at equal intervals
from each other. The examiner concludes that it would have been
obvious to the artisan to space adjacent emitter junctions at the
claimed interval in order to equalize the temperature
distribution along the entire transistor [answer, page 3].
Appellant argues that Fukino gives a numerical example of
his spacing in which the interval nearest the central region is
only 5% larger than the next-nearest interval to the central
region. Appellant asserts that the difference between a 5%
spacing arrangement and a 50% spacing arrangement is more than a
Appeal No. 96-0019
Application 08/150,742
6
mere selection of optimum values and is unobvious [brief, pages
3-4].
The examiner responds that the differences in materials
used by appellant and Fukino account for the differences in
intervals used, and the artisan would have found appellant’s
intervals obvious in equalizing temperatures for appellant’s
prior art transistor [answer, page 3].
We agree with the position taken by the examiner. The
artisan would have appreciated that the temperature distribution
in a plural emitter junction transistor is affected by all the
materials used and by all the dimensions of the various layers.
That is, different semiconductor materials, insulating materials
and metallic materials have different thermal conductivities and
would, therefore, have an effect on the temperature distribution
of the transistor. Likewise, the dimensions chosen for the
various layers would affect the temperature distribution.
Finally, the range of currents for which the transistor was
designed would dictate the amounts of heat which would have to be
accounted for. All these factors would be taken into account in
determining the optimum spacing as taught by Fukino.
Alderstein teaches that transistors constructed of the
materials disclosed by appellant were known devices in the prior
Appeal No. 96-0019
Application 08/150,742
7
art. Fukino would have suggested to the artisan that the equal
emitter junction intervals of Alderstein should be varied in the
manner suggested by Fukino so as to equalize the temperature
distribution along the entire transistor. The question is
whether the claimed 50% interval change would have been obvious
to the artisan within the meaning of 35 U.S.C. § 103.
Fukino teaches that the intervals should be adjusted “by
means of calculation so that all the collector junctions on the
whole surface will exhibit substantially a uniform temperature
rise” [column 3, lines 50-52]. Thus, Fukino is attempting to
achieve the very same result disclosed by appellant which is to
generate a uniform temperature across the transistor. In our
view, once a power transistor having specific materials and
dimensions exists, the calculation to equalize temperature
distribution along the various junctions is straightforward and
generally yields a single solution. Thus, we agree with the
examiner that the intervals in Fukino differ from the claimed
intervals only because they do not involve the exact same
transistor. The calculation of the intervals could probably
produce just about any result depending on the configuration and
dimensions of the Alderstein transistor which is to be modified
according to the teachings of Fukino.
Appeal No. 96-0019
Application 08/150,742
8
If appellant’s claimed intervals equalize temperature
distribution as disclosed, and if Fukino’s intervals equalize
temperature distribution as taught therein, one must conclude
that the differences only result from the fact that the Fukino
transistor is different from appellant’s transistor. Therefore,
we are of the view that if appellant’s heterojunction transistor
with equal junction intervals existed in the prior art, the
claimed interval modifications to equalize temperature would have
been compelled by the calculations suggested by Fukino. Since
all the evidence in this case supports the position that the
transistor with equal junction intervals existed in the prior
art, we conclude that the claimed intervals for this particular
prior art transistor would have been obvious to the artisan when
trying to equalize the junction temperatures of this transistor.
For all the reasons just discussed, we sustain the
examiner’s rejection of independent claim 24. Since dependent
claims 25-28 stand or fall with claim 24, supra, we also sustain
the rejection of these claims. Accordingly, the decision of the
examiner rejecting claims 24-28 is affirmed.
No time period for taking any subsequent action in
connection with this appeal may be extended under 37 CFR
§ 1.136(a).
Appeal No. 96-0019
Application 08/150,742
9
AFFIRMED
)
ERROL A. KRASS )
Administrative Patent Judge )
)
)
) BOARD OF PATENT
JERRY SMITH )
Administrative Patent Judge ) APPEALS AND
)
) INTERFERENCES
)
LEE E. BARRETT )
Administrative Patent Judge )
Michael K. Skrehot
TEXAS INSTRUMENTS INCORPORATED
Patent Department, M/S 219
P. O. Box 655474
Dallas, TX 75265