  United States Court of Appeals
      for the Federal Circuit
               ______________________

           IDEMITSU KOSAN CO., LTD.,
                   Appellant

                          v.

                   SFC CO. LTD.,
                      Appellee
               ______________________

                     2016-2721
               ______________________

    Appeal from the United States Patent and Trademark
Office, Patent Trial and Appeal Board in No. IPR2015-
00564.
                 ______________________

             Decided: September 15, 2017
               ______________________

    JACOB ANDREW DOUGHTY, Oblon, McClelland, Maier
& Neustadt, LLP, Alexandria, VA, argued for appellant.
Also represented by RICHARD KELLY, YUKI ONOE.

   BLAS P. ARROYO, Alston & Bird LLP, Charlotte, NC,
argued for appellee. Also represented by ROBERT FLYNT
STREAN.
                ______________________

Before PROST, Chief Judge, O’MALLEY, and CHEN, Circuit
                       Judges.
2                    IDEMITSU KOSAN CO., LTD.   v. SFC CO. LTD.



O’MALLEY, Circuit Judge.
     Idemitsu Kosan Co., Ltd. (“Idemitsu”) seeks review of
the July 29, 2016 decision of the Patent Trial and Appeal
Board (“the Board”) finding claims 1–5, 7–11, 13, and 14
of U.S. Patent No. 8,334,648 (“the ’648 patent”) invalid as
obvious over International Publication WO 02/052904
(“Arakane”). See SFC Co. Ltd. v. Idemitsu Kosan Co.,
Ltd., No. IPR2015-00564, 2016 Pat. App. LEXIS 13340
(P.T.A.B. July 29, 2016). For the following reasons, we
affirm.
                     I. BACKGROUND
    Idemitsu is the owner of the ’648 patent, titled “Or-
ganic Electroluminescence Device and Organic Light
Emitting Medium.” In brief, the ’648 patent claims a
device containing a particular organic medium layered
between an anode and cathode; when a voltage is applied
through the electrodes, the organic medium emits light.
See ’648 Patent, at Abstract. Claim 1 is representative:
    1. An electroluminescence device comprising a
    pair of electrodes and a layer of an organic light
    emitting medium disposed between the pair of
    electrodes, wherein the layer of an organic light
    emitting medium is present as a light emitting
    layer and comprises:
    (A) an arylamine compound represented by formu-
    la V:




                           (V)


    wherein X3 is a substituted or unsubstituted py-
    rene residue, Ar5 and Ar6 each independently rep-
    resent a substituted or unsubstituted monovalent
IDEMITSU KOSAN CO., LTD.   v. SFC CO. LTD.              3



   aromatic group having 6 to 40 carbon atoms, and
   p represents an integer of 1 to 4; and
   (B) at least one compound selected from the group
   consisting of anthracene derivatives and spiroflu-
   orene derivatives, wherein said anthracene deriv-
   atives are represented by formula I:
                      A1–L–A2         (I)
   wherein A1 and A2 may be the same or different
   and each independently represent a substituted or
   unsubstituted monophenylanthryl group or a sub-
   stituted or unsubstituted diphenylanthryl group,
   and L represents a single bond or a divalent bond-
   ing group, and by formula II:
                      A3–An–A4 (II)
   wherein An represents a substituted or unsubsti-
   tuted divalent anthracene residue, A3 and A4 may
   be the same or different and each independently
   represent a substituted or unsubstituted aryl
   group having 6 to 40 carbon atoms, at least one of
   A3 and A4 represents a substituted or unsubsti-
   tuted monovalent condensed aromatic ring group
   or a substituted or unsubstituted aryl group hav-
   ing 10 or more carbon atoms; and said spirofluo-
   rene derivatives are represented by formula III:




                              (III)


   wherein Ar1 represents a substituted or unsubsti-
   tuted spirofluorene residue, A5 to A8 each inde-
   pendently     represent    a    substituted   or
   unsubstituted aryl group having 6 to 40 carbon
4                   IDEMITSU KOSAN CO., LTD.   v. SFC CO. LTD.



    atoms; provided that the organic light emitting
    medium does not include a styryl aryl compound.
Id. at col. 132 ll. 2–64. Claim 13 is the only other inde-
pendent claim, and covers only the “organic light emitting
medium” disclosed by the same formulae above. Id. at col.
136 ll. 3–56.
    Arakane is also assigned to Idemitsu, and—translated
from Japanese into English—is titled “Organic Electro-
luminescence Device.” Arakane at 1. Like the ’648 pa-
tent, Arakane teaches an “organic electroluminescence
device”:
    The present invention provides an organic electro-
    luminescence device including a pair of electrodes
    and an organic light emitting medium layer inter-
    posed between the electrodes wherein the organic
    light emitting medium layer has a mixture layer
    containing (A) at least one hole transporting
    [“HT”] compound and (B) at least one electron
    transporting [“ET”] compound and the energy gap
    Eg1 of the [HT] compound and the energy gap Eg2
    of the [ET] compound satisfy the relation
    Eg1<Eg2.
Id. at 4. Arakane additionally describes preferred formu-
lae for its HT and ET compounds. Among others, for the
HT compound, Arakane discloses an arylamine compo-
nent with a condensed ring structure:
IDEMITSU KOSAN CO., LTD.   v. SFC CO. LTD.                5



Id. at 5–6. And among others for the ET compound,
Arakane discloses an anthracene derivative represented
by either of the following formulae:
                           A1-L-A2     (5)
                           A3-An-A4    (6)
Id. at 18. “A1 and A2, which may be the same or different,
each independently represent a substituted or unsubsti-
tuted monophenylanthryl group or a substituted or un-
substituted diphenylanthryl group and L represents a
single bond or a divalent linking group.” Id. The notation
“An,” on the other hand, “represents a substituted or
unsubstituted anthracene radical and A3 and A4, which
may [be] the same or different, each independently repre-
sent a substituted C10-C40 monovalent condensed aromatic
ring group or a substituted or unsubstituted C12-C40 non-
condensed aryl group.” Id.
    SFC Co. Ltd. (“SFC”) petitioned for inter partes
review of all claims (1–15) of the ’648 patent on various
grounds, and the Board instituted review on a single
ground: whether claims 1–5, 7–11, and 13–14 were obvi-
ous over Arakane. See SFC Co. Ltd. v. Idemitsu Kosan
Co., Ltd., No. IPR2015-00564, 2015 2015 WL 4760582, at
*8-9 (P.T.A.B. Aug. 7, 2015). The Board ultimately held
that all instituted claims were obvious, finding in particu-
lar that: (i) Arakane’s formula (1) HT compound corre-
sponds to the ’648 patent’s formula V compound; (ii)
Arakane’s formula (5) and (6) ET compounds correspond
to the ’648 patent’s formula (I) and (II) compounds, re-
spectively; and (iii) Arakane teaches that a light emitting
layer can be formed by combining an HT and ET com-
pound. Id. at 13–15, 19–20. Idemitsu timely appealed to
this court.
                 II. STANDARD OF REVIEW
    “Whether a claimed invention is unpatentable as ob-
vious under § 103 is a question of law based on underlying
6                    IDEMITSU KOSAN CO., LTD.   v. SFC CO. LTD.



findings of fact.” In re Gartside, 203 F.3d 1305, 1316
(Fed. Cir. 2000). Underlying factual findings include:
“[t]he identification of analogous prior art,” In re Bigio,
381 F.3d 1320, 1324 (Fed. Cir. 2004); “[w]hat the prior art
teaches and whether it teaches toward or away from the
claimed invention,” Para-Ordnance Mfg., Inc. v. SGS
Importers Int’l, Inc., 73 F.3d 1085, 1088 (Fed. Cir. 1995);
and the “existence of a reason for a person of ordinary
skill to combine references,” In re Hyon, 679 F.3d 1363,
1365–66 (Fed. Cir. 2012). The Board’s findings of fact
concerning obviousness are reviewed for substantial
evidence. On-Line Careline, Inc. v. Am. Online, Inc., 229
F.3d 1080, 1085 (Fed. Cir. 2000).
                     III. DISCUSSION
    On appeal, Idemitsu does not appear to challenge the
Board’s factual findings with respect to the correspond-
ence between the ’648 patent’s components and some of
the compounds disclosed by Arakane. Rather, Idemitsu
argues that the Board erred in finding that Arakane
taught combining those particular compounds for the
purpose of creating a light emitting layer in an electrolu-
minescent device. See Appellant Br. 25–27. Specifically,
Idemitsu claims that Arakane features a requirement
that, “when combined in a layer, the HT compound and
the ET compound must be selected so that the energy gap
of the HT compound is smaller than the energy gap of the
ET compound.” Id. at 26 (citing Arakane at 4). Idemitsu
observes that the Board made no findings with respect to
the energy gap relationship of the particular HT/ET
combination corresponding to the ’648 patent’s compo-
nents. Id. at 26–27. Hence, Idemitsu argues, the Board
must have made one of two erroneous assumptions in
order to find that Arakane nevertheless taught the com-
bination thereof: either (1) a skilled artisan would have
expected that all disclosed HT compounds in Arakane
have a lower energy gap than all disclosed ET compounds;
or (2) Arakane suggests combinations of HT and ET
IDEMITSU KOSAN CO., LTD.   v. SFC CO. LTD.               7



compounds that do not satisfy the energy gap relation in
addition to combinations that do. We address each as-
sumption in turn.
    We find that the Board plainly did not make the first
assumption. The portions of the Board’s decision that
Idemitsu cites demonstrate that the Board was merely
restating SFC’s argument—not adopting it:
   In response to Patent Owner’s arguments regard-
   ing an alleged energy gap requirement, Petitioner
   takes the position that Arakane “tells you [that]
   you want this preferred energy gap relationship,
   and then it tells you these are the compounds to
   use, [and] that presumptively those compounds
   have that desired energy gap relationship.” Tr.
   45:7–13; see id. at 44:17–23, 47:4–7 (agreeing that
   it is reasonable to read Arakane’s disclosure as
   saying “if you take any one of these As and any
   one of these Bs and put them together, it will
   work”). Petitioner further contends that Patent
   Owner’s reliance on Comparative Example 4 is
   misplaced, because Comparative Example 4 uti-
   lizes a hole transporting compound (TPD) that
   does not fall within Arakane’s preferred group of
   hole transporting compounds, i.e., it is not an ar-
   omatic amine having a condensed ring structure.
   Reply 12. In contrast, Examples 1–4 utilize pre-
   ferred hole transporting compounds. Id.
Idemitsu, 2016 Pat. App. LEXIS 13340, at *24-25 (empha-
sis added). But the Board itself took a different approach:
   Claims 1 and 13 of the ’648 patent require the
   combination of components (A) and (B) in a light
   emitting layer. Claims 1 and 13 do not include
   any limitations directed to the energy gap charac-
   teristics of the individual components or particu-
   lar performance characteristics of the light
   emitting layer, such as half-life or efficiency.
8                    IDEMITSU KOSAN CO., LTD.   v. SFC CO. LTD.



    Thus, the “claimed invention as a whole” is the
    combination of the recited components in a light
    emitting layer. As discussed in detail below, Ara-
    kane’s disclosure would have informed an ordi-
    nary artisan that combining components (A) and
    (B) would produce a light emitting layer. The suf-
    ficiency of that disclosure to establish the obvi-
    ousness of the combination does not depend on
    whether the resulting light emitting layer would
    satisfy Arakane’s energy gap relationship or the
    desired stability and heat resistance criteria.
Id. at *25-26 (emphasis added); see also id. at *27 (“This
teaching regarding the energy gap relationship, however,
does not diminish Arakane’s disclosure of the fundamen-
tal concept of forming a light emitting layer containing a
mixture of at least two components, (A) a hole transport-
ing compound and (B) an electron transporting com-
pound.”). In other words, the Board found that Arakane
teaches that combining any of the listed HT compounds
with any of the ET compounds would produce a light
emitting layer, and that—if the combination additionally
satisfies the energy gap relationship—then it will feature
improved durability and efficiency as well. Id. at *27-29.
    The Board, if it made any assumption, made the
second one Idemitsu describes: finding that Arakane
suggests combinations of HT and ET compounds that do
not satisfy the energy gap relation in addition to combina-
tions that do. More precisely, it found that Arakane
suggests combinations of HT and ET compounds that
produce a light emitting layer, regardless of their energy
gap relation. We discern no error in that finding.
    Idemitsu first contends that this argument was
“raised too late,” because it “d[id] not appear in SFC’s
petition or the [Board]’s institution decision.” Appellant
Br. 37–38. Idemitsu’s contention misconstrues not only
the record, but our case law as well. A review of the
IDEMITSU KOSAN CO., LTD.   v. SFC CO. LTD.                9



proceedings below reveals the following chain of argu-
ments and counterarguments. First, SFC argued in its
petition that “Arakane teaches (i) that the [HT] compound
can be an arylamine compound corresponding to Formula
(V) of claims 1 and 13, (ii) that the [ET] compound can be
anthracene derivatives corresponding to Formulas (I) and
(II) of claims 1 and 13, and (iii) that the [HT] compound
and [ET] compound are mixed in the organic light emit-
ting medium.” J.A. 15–16; see also J.A. 189–91. Second,
Idemitsu argued in its response that SFC failed to “ex-
plain why a skilled artisan would have been led to use”
that combination, given that “[t]he energy gap relation-
ship limits the combinations of the compounds . . . encom-
passed by Arakane to combinations satisfying the
relationship.” J.A. 328. Third, SFC countered in its reply
that Arakane does not teach away from “the claimed
combination,” despite “the absence of demonstrating that
the combination would possess the preferred energy gap
relationship,” distinguishing certain comparative exam-
ples. J.A. 382–83; see also Idemitsu, 2016 Pat. App.
LEXIS 13340, at *24-25.
    This back-and-forth shows that what Idemitsu char-
acterizes as an argument raised “too late” is simply the
by-product of one party necessarily getting the last word.
If anything, Idemitsu is the party that first raised this
issue, by arguing—at least implicitly—that Arakane
teaches away from non-energy-gap combinations. SFC
simply countered, as it was entitled to do. To the extent
Idemitsu suggests that the Board could not reach a coun-
terargument because it was not preemptively addressed
by the petition or institution decision, Idemitsu is plainly
mistaken. See Genzyme Therapeutic Prod. Ltd. P’ship v.
Biomarin Pharm. Inc., 825 F.3d 1360, 1366 (Fed. Cir.
2016) (“There is no requirement, either in the Board’s
regulations, in the APA, or as a matter of due process, for
the institution decision to anticipate and set forth every
10                   IDEMITSU KOSAN CO., LTD.   v. SFC CO. LTD.



legal or factual issue that might arise in the course of the
trial.”).
    Idemitsu’s only substantive argument on appeal ap-
pears to be that the Board should not have engaged in
fact-finding on this issue without the benefit of additional
extrinsic evidence, such as expert testimony. See, e.g.,
Appellant Br. 43–44. In some cases, that method of fact-
finding could indeed be problematic. See, e.g., Perfect Web
Techs., Inc. v. InfoUSA, Inc., 587 F.3d 1324, 1330 (Fed.
Cir. 2009) (“If the relevant technology were complex, the
court might require expert opinions.”); Proveris Sci. Corp.
v. Innovasystems, Inc., 536 F.3d 1256, 1267 (Fed. Cir.
2008) (affirming the district court’s requirement of expert
testimony to prove invalidity where “th[e] subject matter
[wa]s sufficiently complex to fall beyond the grasp of an
ordinary layperson”); Brand v. Miller, 487 F.3d 862, 869-
70 (Fed. Cir. 2007) (reversing the Board’s decision to
“reject[] as unconvincing the only relevant testimony” and
independently reach the opposite conclusion).
    But here, Idemitsu provided no such supporting evi-
dence for its own position—that Arakane teaches away
from any non-energy-gap HT/ET combinations. SFC, of
course, bears the ultimate burden of establishing un-
patentability, but it is not required as a matter of law to
rebut mere attorney argument with expert testimony in
order to satisfy that burden. The Board weighed the
parties’ competing arguments—each relying solely on the
text of Arakane itself—and found SFC’s reading to be the
more plausible one. That is precisely what the Board is
supposed to do.
    Idemitsu’s teaching away argument is of questionable
relevance anyway. Evidence concerning whether the
prior art teaches away from a given invention must relate
to and be commensurate in scope with the ultimate claims
at issue. See, e.g., MeadWestVaco Corp. v. Rexam Beauty
and Closures, Inc., 731 F.3d 1258, 1264–65 (Fed. Cir.
IDEMITSU KOSAN CO., LTD.   v. SFC CO. LTD.               11



2013); In re Kahn, 441 F.3d 977, 990 (Fed. Cir. 2006); In
re Zhang, 654 F. App’x 488, 490 (Fed. Cir. 2016) (“While a
prior art reference may indicate that a particular combi-
nation is undesirable for its own purposes, the reference
can nevertheless teach that combination if it remains
suitable for the claimed invention.”) (emphasis added).
Here, it is undisputed that the claims at issue do not
include limitations with respect to half-life or efficiency.
See, e.g., Idemitsu, 2016 Pat. App. LEXIS 13340, at *26;
Appellee Br. 46. Hence, if Arakane teaches that the only
drawback of non-energy-gap HT/ET combinations is poor
performance under those criteria, it is of substantially
reduced importance here.
     Nor, as Idemitsu suggests, was the Board’s finding
unreasonable on the merits. Arakane’s abstract reads as
follows:
   An organic electroluminescence device includes a
   pair of electrodes and an organic luminescent me-
   dium layer interposed between the electrodes.
   The organic luminescent medium layer has a mix-
   ture layer containing (A) at least one hole trans-
   porting compound and (B) at least one electron
   transporting compound. The energy gap Eg1 of
   the hole transporting compound and the energy
   gap Eg2 of the electron transporting compound
   satisfy the relation Eg1<Eg2. Electrons recombine
   with holes in the organic luminescent medium lay-
   er to produce light. The organic electrolumines-
   cence device has a long life and emits light with
   high efficiency.
Arakane at 1 (emphases added). The syntactical struc-
ture is revealing. Arakane’s teaching to combine an HT
compound with an ET compound is separate from its
description of the energy gap; the teaching that hole
recombination produces light is separate from the durabil-
ity and efficiency description. This is mirrored, moreover,
12                    IDEMITSU KOSAN CO., LTD.   v. SFC CO. LTD.



elsewhere in the description—which explicitly pegs the
longer life and efficiency to the energy gap:
     As a result, the present inventors have found that
     when an organic EL device includes an organic
     light emitting medium layer having a mixture
     layer containing (A) at least one hole transporting
     compound whose energy gap E1 is smaller and (B)
     at least one electron transporting compound
     whose energy gap Eg2 is larger, it has a longer life
     and can emit light with higher efficiency than con-
     ventional organic EL devices.
Id. at 3–4 (emphases added). “[C]onventional organic
[electroluminescent] devices” are described in the preced-
ing paragraphs, and broadly include those with HT/ET
combination media. Id. at 2–3. Thus, the Board reasona-
bly concluded that Arakane teaches that a light-producing
device can be made—regardless of comparative shortcom-
ings in durability or resistance caused by imperfect ener-
gy gap ratio—by combining HT and ET compounds,
including the claimed combinations, as the critical layer.
                      IV. CONCLUSION
    After full review of the record and careful considera-
tion, we find no error in the Board’s decision. According-
ly, we affirm.
                        AFFIRMED
                           COSTS
     No costs.
