  United States Court of Appeals
      for the Federal Circuit
                ______________________

          CONTINENTAL CIRCUITS LLC,
                Plaintiff-Appellant

                           v.

     INTEL CORPORATION, IBIDEN U.S.A.
  CORPORATION, IBIDEN COMPANY LIMITED,
             Defendants-Appellees
            ______________________

                      2018-1076
                ______________________

    Appeal from the United States District Court for the
District of Arizona in No. 2:16-cv-02026-DGC, Judge David
G. Campbell.
                  ______________________

               Decided: February 8, 2019
                ______________________

     JEFFREY A. LAMKEN, MoloLamken LLP, Washington,
DC, argued for plaintiff-appellant. Also represented by
MICHAEL GREGORY PATTILLO, JR., BENJAMIN THOMAS
SIROLLY; BRADLEY WAYNE CALDWELL, JASON DODD
CASSADY, JOHN AUSTIN CURRY, WARREN JOSEPH MCCARTY,
III, Caldwell Cassady & Curry, Dallas, TX.

      JOSEPH J. MUELLER, Wilmer Cutler Pickering Hale
and Dorr LLP, Boston, MA, argued for defendants-appel-
lees. Also represented by KEVIN GOLDMAN, RICHARD WELLS
O'NEILL, SARAH B. PETTY, KEVIN SCOTT PRUSSIA; NINA S.
2           CONTINENTAL CIRCUITS LLC v. INTEL CORPORATION




TALLON, Washington, DC. Defendant-appellee Intel Cor-
poration also represented by MATTHEW JOHN HULT, Intel
Corporation, Santa Clara, CA.
                 ______________________

    Before LOURIE, LINN, and TARANTO, Circuit Judges.
LOURIE, Circuit Judge.
     Continental Circuits LLC appeals from the judgment
of the United States District Court for the District of Ari-
zona of noninfringement of the asserted claims of U.S. Pa-
tents 7,501,582 (“the ’582 patent”); 8,278,560 (“the ’560
patent”); 8,581,105 (“the ’105 patent”); and 9,374,912 (“the
’912 patent”). See Final Judgment, Cont’l Circuits LLC v.
Intel Corp., No. 16-2026 (D. Ariz. Sept. 12, 2017), ECF No.
273. The parties stipulated to a judgment of noninfringe-
ment, see Stipulation & Joint Motion, Cont’l Circuits LLC
v. Intel Corp., No. 16-2026 (D. Ariz. Sept. 7, 2017), ECF No.
266, based on the district court’s claim construction of cer-
tain claim terms, see Cont’l Circuits LLC v. Intel Corp., No.
16-2026, 2017 WL 3478659 (D. Ariz. Aug. 9, 2017) (“Claim
Construction Order”). Because we conclude that the dis-
trict court erred in its claim construction, we vacate the
judgment of noninfringement and remand for further pro-
ceedings.
                       BACKGROUND
    Continental owns the ’582, ’560, ’105, and ’912 patents,
which are directed to a “multilayer electrical device . . .
having a tooth structure” and methods for making the
same. See, e.g., ’582 patent Abstract. The four patents at
issue, which have since expired, are continuations of one
another and thus share substantially the same
CONTINENTAL CIRCUITS LLC v. INTEL CORPORATION                3



specification. 1 According to the patents, multilayer electric
devices “suffer from delamination, blistering, and other re-
liability problems,” especially when “subjected to thermal
stress.” Id. col. 1 ll. 30–32. The inventions of the patents
purport to solve this problem by “forming a unique surface
structure . . . comprised of teeth that are preferably angled
or hooked like fangs or canine teeth to enable one layer to
mechanically grip a second layer.” Id. col. 1 ll. 52–57. The
specification further explains that the increased surface
area of the teeth improves the adhesion of the layers to one
another. See id. col 1 l. 58–col. 2 l. 6.
     The patents additionally “theorize[] . . . that the best
methods for producing the teeth [are] to use non-homoge-
nous materials and/or techniques . . . such that slowed
and/or repeated etching will form teeth instead of a uni-
form etch.” Id. col. 2 ll. 24–29. The specification then ex-
plains that “[o]ne technique for forming the teeth is . . . the
swell and etch or desmear process, except that contrary to
all known teachings in the prior art . . . a ‘double desmear
process’ is utilized.” Id. col. 5 ll. 40–44. It continues by
explaining that “the peel strength produced in accordance
with the present invention is greater than the peal [sic]
strength produced by the desmear process of the prior art,
i.e., a single pass desmear process.” Id. col. 7 ll. 3–6. The
specification then discloses that “[i]n stark contrast with
the etch and swell process of the known prior art . . . a sec-
ond pass through the process . . . is used” because it
“make[s] use of [the] non-homogenaities [sic] in bringing
about a formation of the teeth.” Id. col. 9 ll. 1–5.
    Continental sued Intel Corp.; its supplier, Ibiden
U.S.A. Corp.; and Ibiden U.S.A. Corp.’s parent company,
Ibiden Co. Ltd. (collectively, “Intel”), for patent


    1   In this opinion, citations are only to the ’582 patent
specification because the specifications of the four patents
are substantially identical.
4            CONTINENTAL CIRCUITS LLC v. INTEL CORPORATION




infringement in the District of Arizona. Continental as-
serted claims 85, 87, 89, 92, 94, 95, 100, 109, 114, and 122
of the ’582 patent; claims 14 and 19 of the ’560 patent;
claims 13, 53, 71, 80, 82, 86, 88, 91, 95, 97, 101, and 103 of
the ’105 patent; and claims 2, 3, 18–20, and 26–28 of the
’912 patent. All of the asserted claims include claim limi-
tations regarding the “surface,” “removal,” or “etching” of
“a dielectric material” or “epoxy,” which the district court
construed together as the “Category 1 Terms,” and their
construction depends on resolving whether they should be
limited to a repeated desmear process. See Claim Con-
struction Order, 2017 WL 3478659, at *2; see also J.A.
1879–89. 2
    Claim 100 of the ’582 patent is illustrative of a claim
that includes a “surface” claim term and reads as follows:
    100. An electrical device including:
    a conductive layer built up so as to fill undercut-
    tings with respect to a surface of a dielectric mate-
    rial so as to form teeth in cavities, a plurality of the
    undercuttings being obtuse to the surface, wherein




    2   The Category 1 Terms include “surface,” “removal,”
and “etching” related claim terms:
   • The “surface” claim terms are “surface of a dielectric
      material,” “surface of a layer of a dielectric mate-
      rial,” and “a dielectric material comprising a sur-
      face.”
   • The “removal” claim terms are “removal of a portion
      of the dielectric material,” and “removal of some of
      the dielectric material.”
   • The “etching” claim terms are “etching [of] the
      epoxy” and “etching [of] the dielectric material.”
The district court construed all of these claim terms to-
gether.
CONTINENTAL CIRCUITS LLC v. INTEL CORPORATION                5



    the conductive layer is a portion of circuitry of an
    electrical device, and a plurality of the teeth are
    within the range of 1 tenth of a mil deep to 1.75
    tenths of a mil deep, and
    wherein at least one of the cavities includes an up-
    grade slope with respect to the surface of the dielec-
    tric material, and one of the teeth engages a portion
    of the dielectric material at the slope.
’582 patent col. 18 ll. 48–59 (emphases added).
    Claim 114 of the ’582 patent is representative of a claim
that includes a “removal” claim term and reads as follows:
    114. An electrical device including:
    a dielectric material having a surface remaining
    from removal of a portion of the dielectric material;
    and
    means for mechanically gripping a conductive layer
    to the surface of the dielectric material so that the
    conductive layer is burrowed in and under the top
    surface of the dielectric material, wherein the con-
    ductive layer forms a portion of circuitry of an elec-
    trical device, wherein the means for mechanically
    gripping is comprised of teeth, and a plurality of
    the teeth are within the range of 1 tenth of a mil
    deep to 1.75 tenths of a mil deep, and
    wherein at least one of the cavities includes an up-
    grade slope with respect to the surface of the die-
    lectric material, and one of the teeth engages a
    portion of the dielectric material at the slope.
Id. col. 20 ll. 30–44 (emphasis added).
    Claim 14 of the ’560 patent is representative of a claim
that includes an “etching” claim term and reads as follows:
    14. An article of manufacture, the article compris-
    ing:
6           CONTINENTAL CIRCUITS LLC v. INTEL CORPORATION




    an epoxy dielectric material delivered with solid
    content sufficient that etching the epoxy forms a
    non-uniformly roughened surface comprising cavi-
    ties located in and underneath a surface of the die-
    lectric material, and sufficient that the etching of
    the epoxy uses non-homogeneity with the solid con-
    tent to bring about formation of the non-uniformly
    roughened surface with at least some of the cavities
    having a first cross-sectional distance proximate
    the initial surface and a substantially greater
    cross-sectional distance distant from the initial
    surface, and
    a conductive material, whereby the etching of the
    epoxy forms the cavities, and a portion of the con-
    ductive material in the cavities thereby forming
    teeth in the cavities, wherein the etching of the
    non-homogeneous composition forms the cavities,
    and wherein the conductive material forms a por-
    tion of circuitry of an electrical device.
’560 patent col. 10 ll. 7–25 (emphases added).
    Aside from the “device” and “article of manufacture”
claims recited above, the asserted claims also include pro-
cess and product-by-process claims. Claims 2 and 18 of the
’912 patent are illustrative and read as follows:
    2. A process of making an article of manufacture,
    the process comprising:
    implementing a circuit design for an electrical de-
    vice by coupling a dielectric material delivered with
    solid content, the dielectric material and the solid
    content being non-homogeneous materials, suffi-
    cient that etching the dielectric material forms a
    non-uniformly roughened surface comprising cavi-
    ties located in, and underneath a surface of, the di-
    electric material, and sufficient that the etching of
    the dielectric material uses non-homogeneity with
CONTINENTAL CIRCUITS LLC v. INTEL CORPORATION                 7



    the solid content in bringing about formation of the
    non-uniformly roughened surface with at least
    some of the cavities having a first cross-sectional
    distance proximate the surface and a greater cross-
    sectional distance distant from the surface, with
    a conductive material, whereby the etching of the
    dielectric material forms the cavities, and a portion
    of the conductive material in the cavities thereby
    forming teeth in the cavities, wherein the etching
    of the non-homogeneous composition forms the cav-
    ities, in circuitry of the electrical device.
    ....
    18. A product produced by the process of claim 2.
’912 patent col. 9 l. 58–col. 10 l. 11, col. 11 l. 14.
     The district court construed the Category 1 Terms to
require that the “surface,” “removal,” or “etching” of the di-
electric material be “produced by a repeated desmear pro-
cess.” See Claim Construction Order, 2017 WL 3478659, at
*2–3 (emphasis added). The district court concluded that
Intel had “met the exacting standard required” to read a
limitation into the claims. Id. at *3. Specifically, the dis-
trict court found that the specification not only “repeatedly
distinguishe[d] the process covered by the patent from the
prior art and its use of a ‘single desmear process,’” id. at *4,
but also characterized “the present invention” as using a
repeated desmear process, see id. at *5.
    Additionally, the district court found that the prosecu-
tion history corroborated its construction. The examiner
made indefiniteness and written description rejections dur-
ing the prosecution of the ’560 patent of the claim limita-
tion “etching of the epoxy uses non-homogeneity with the
solid content,” which is used to bring about formation of the
non-uniformly roughened surface of the angular tooth-
shaped cavities. See J.A. 2122–23. In response to the office
action, Continental submitted an expert declaration
8           CONTINENTAL CIRCUITS LLC v. INTEL CORPORATION




explaining that the “etching” process disclosed in the spec-
ification uses “this known Probelec XB[ ]7081 resin” and
“two separate swell and etch steps” as “a technique which
forms the teeth.” J.A. 2074; see also J.A. 2068–69. The
district court found that the expert declaration “clearly de-
scribe[d] the patented method as involving two etching pro-
cesses.” Claim Construction Order, 2017 WL 3478659, at
*6. Moreover, the district court observed that extrinsic doc-
uments produced by the inventors state the use of a “two
pass desmear cycle” and that “we use a double pass
desmear to achieve the tooth structure.” Id. (quoting J.A.
3321, 3324). The court acknowledged that those state-
ments were “not reliable enough to be dispositive,” but
found they “provide[d] helpful corroboration.” Id.
    Based on the court’s claim construction and the fact
that all of the asserted claims involve the question whether
they should be limited to a repeated desmear process, the
parties stipulated to noninfringement and the court en-
tered judgment accordingly. On appeal, Continental chal-
lenges only the district court’s claim construction. We have
jurisdiction under 28 U.S.C. § 1295(a)(1).
                        DISCUSSION
    Claim construction is ultimately a question of law that
we review de novo. Teva Pharm. USA, Inc. v. Sandoz, Inc.,
135 S. Ct. 831, 841 (2015). Any subsidiary factual findings
based on extrinsic evidence “must be reviewed for clear er-
ror on appeal.” Id. But “when the district court reviews
only evidence intrinsic to the patent (the patent claims and
specifications, along with the patent’s prosecution history),
the judge’s determination will amount solely to a determi-
nation of law,” which we review de novo. Id.

    Continental argues that the district court erred in con-
struing the Category 1 Terms to require that the dielectric
CONTINENTAL CIRCUITS LLC v. INTEL CORPORATION               9



material be “produced by a repeated desmear process.” 3
See Claim Construction Order, 2017 WL 3478659, at *2–3.
Continental contends that the plain language of the claims
does not include a repeated desmear process. Also, accord-
ing to Continental, the specification does not clearly and
unmistakably limit the claims to require a repeated
desmear process. Although Continental acknowledges that
the preferred embodiment discusses using a repeated
desmear process, Continental argues that it is not proper
to limit the claims to the preferred embodiment. Continen-
tal next contends that the expert declaration cited by the
district court, which applicants invoked to respond to in-
definiteness and written description rejections by the ex-
aminer, does not include a clear and unmistakable
disavowal for prosecution disclaimer to attach. Finally,
Continental argues that the inventor documents cited by
the district court merely reflect the inventors practicing the
preferred embodiment and thus lend no support for the dis-
trict court’s construction.
     Intel responds that it was proper for the district court
to limit the claims to a repeated desmear process because
the patentees repeatedly disparaged and disavowed the
single-pass desmear process and expressly defined “the
present invention” as requiring a repeated desmear



    3   We note that the specification discusses use of a
“double desmear process” while the district court construed
the claims to require a “repeated desmear process.” Com-
pare generally ’582 patent, with Claim Construction Order,
2017 WL 3478659, at *2–3 (emphasis added). The parties
do not argue this difference is material, and because we ul-
timately do not agree with the district court that the claim
limitation should have been read into the claims, the dif-
ference in wording does not impact the outcome. Thus, for
purposes of this opinion, we assume the terms are inter-
changeable.
10           CONTINENTAL CIRCUITS LLC v. INTEL CORPORATION




process. Intel also argues that the prosecution history fur-
ther supports reading in this limitation because the expert
declaration submitted during prosecution reiterated that
“the claimed invention is directed to surface roughening
performed by ‘two separate’ passes of a desmear process.”
Appellee’s Br. 29. Furthermore, Intel contends that docu-
ments authored by the inventors demonstrate an inability
to obtain the desired levels of roughening using a single-
pass desmear process, which confirms that their alleged in-
vention was limited to a repeated desmear process.
     We agree with Continental that the district court erred
in limiting the claims to require a repeated desmear pro-
cess. In construing claims, district courts give claims their
ordinary and customary meaning, which is “the meaning
that the term would have to a person of ordinary skill in
the art in question at the time of the invention.” Phillips
v. AWH Corp., 415 F.3d 1303, 1312–13 (Fed. Cir. 2005) (en
banc). “[B]ecause patentees frequently use terms idiosyn-
cratically, the court looks to” sources including “the words
of the claims themselves, the remainder of the specifica-
tion, the prosecution history, and extrinsic evidence con-
cerning relevant scientific principles, the meaning of
technical terms, and the state of the art.” Id. at 1314 (quot-
ing Innova/Pure Water, Inc. v. Safari Water Filtration
Sys., Inc., 381 F.3d 1111, 1116 (Fed. Cir. 2004)).
    From this list of sources, “the claims themselves pro-
vide substantial guidance as to the meaning of particular
claim terms.” Id. However, the claims “do not stand
alone.” Id. at 1315. They are part of “‘a fully integrated
written instrument,’ consisting principally of a specifica-
tion that concludes with the claims,” and must therefore
“be read in view of the specification.” Id. (quoting Mark-
man v. Westview Instruments, Inc., 52 F.3d 967, 978–79
(Fed. Cir. 1995)). Accordingly, the specification “is always
highly relevant to the claim construction analysis. Usu-
ally, it is dispositive; it is the single best guide to the
CONTINENTAL CIRCUITS LLC v. INTEL CORPORATION              11



meaning of a disputed term.” Id. (quoting Vitronics Corp.
v. Conceptronic, Inc., 90 F.3d 1576, 1582 (Fed. Cir. 1996)).
     “In addition to consulting the specification, we have
held that a court ‘should also consider the patent’s prose-
cution history, if it is in evidence.’” Id. at 1317 (quoting
Markman, 52 F.3d at 980). “Like the specification, the
prosecution history provides evidence of how the [United
States Patent and Trademark Office (“PTO”)] and the in-
ventor understood the patent.” Id. We have cautioned,
however, that “because the prosecution history represents
an ongoing negotiation between the PTO and the applicant,
rather than the final product of that negotiation, it often
lacks the clarity of the specification and thus is less useful
for claim construction purposes.” Id.
    With these principles in mind, we turn to the construc-
tion of the Category 1 Terms. Beginning with the claim
language, we first note that none of the asserted claims ac-
tually recite a “repeated desmear process.” Accord Claim
Construction Order, 2017 WL 3478659, at *2. Thus, at
least based on the plain language, the claims are not lim-
ited to a repeated desmear process.
     We continue our analysis by reading the claims “in
view of the specification, of which they are a part.” Phil-
lips, 415 F.3d at 1315 (quoting Markman, 52 F.3d at 979).
Our case law has recognized that “the specification may re-
veal a special definition given to a claim term by the pa-
tentee that differs from the meaning it would otherwise
possess.” Id. at 1316. When the patentee acts as its own
lexicographer, that definition governs. See id. “To act as
its own lexicographer, a patentee must ‘clearly set forth a
definition of the disputed claim term’ other than its plain
and ordinary meaning.” Thorner v. Sony Comput. Entm’t
Am. LLC, 669 F.3d 1362, 1365 (Fed. Cir. 2012) (quoting
CCS Fitness, Inc. v. Brunswick Corp., 288 F.3d 1359, 1366
(Fed. Cir. 2002)). We have also found instances where “the
specification may reveal an intentional disclaimer, or
12           CONTINENTAL CIRCUITS LLC v. INTEL CORPORATION




disavowal, of claim scope.” Phillips, 415 F.3d at 1316. In
those situations, it is again the inventor’s disavowal that is
dispositive of the claim construction. See id. “To disavow
claim scope, the specification must contain ‘expressions of
manifest exclusion or restriction, representing a clear dis-
avowal of claim scope.’” Retractable Techs., Inc. v. Becton,
Dickinson & Co., 653 F.3d 1296, 1306 (Fed. Cir. 2011)
(quoting Epistar Corp. v. Int’l Trade Comm’n, 566 F.3d
1321, 1335 (Fed. Cir. 2009)).
    We acknowledge the difficulty in drawing the “fine line
between construing the claims in light of the specification
and improperly importing a limitation from the specifica-
tion into the claims.” Id. at 1305. To avoid improperly im-
porting limitations into the claims, “it is important to keep
in mind that the purposes of the specification are to teach
and enable those of skill in the art to make and use the
invention and to provide a best mode for doing so.” Phil-
lips, 415 F.3d at 1323.
     Based on our review of the specification, none of the
statements relied upon by the district court rises to the
level of “a clear and unmistakable disclaimer.” Thorner,
669 F.3d at 1367. The specification begins by explaining
that the invention is an “electrical device” with teeth. See
’582 patent col. 1 ll. 13–15, col. 1 l. 50–col. 2 l. 6. The spec-
ification then explains that “[o]ne technique for forming the
teeth,” which is “contrary to all known teachings in the
prior art” is the double desmear process. See id. col. 5 ll.
40–44 (emphasis added). Additionally, the disclosures pro-
vide that “the present invention can be carried out by a new
use” of a dielectric material called Probelec XB 7081. See
id. col. 6 ll. 41–48 (emphasis added). And within this con-
text, “[f]or example, the present invention differs from the
common desmear process in that sub-steps in the desmear
process are repeated as a way of forming the teeth.” Id. col.
8 ll. 49–52 (emphases added). This, the patent explains, is
“[i]n stark contrast with the etch and swell process of the
known prior art.” Id. col. 9 ll. 1–2. The specification also
CONTINENTAL CIRCUITS LLC v. INTEL CORPORATION              13



notes that the peel strength produced by the new use of
Probelec XB 7081 is greater than that of “the prior art, i.e.,
a single pass desmear process.” See id. col. 7 ll. 3–9.
    Overall, those statements simply describe how to make
the claimed invention using the preferred Probelec XB
7081 in a “new” way that is different from the prior art pro-
cess and are not statements clearly limiting the claimed
“electrical device” to require a repeated desmear process.
Heeding the warning in Phillips to keep in mind that a goal
of the specification is to provide a best mode to make and
use an invention, phrases such as “one technique,” “can be
carried out,” and “a way” indicate that using Probelec XB
7081 is only one method for making the invention and does
not automatically lead to finding a clear disavowal of claim
scope. See Phillips, 415 F.3d at 1323. We have also “ex-
pressly rejected the contention that if a patent describes
only a single embodiment, the claims of the patent must be
construed as being limited to that embodiment.” Id.; see
also Liebel-Flarsheim Co. v. Medrad, Inc., 358 F.3d 898,
906 (Fed. Cir. 2004) (“Even when the specification de-
scribes only a single embodiment, the claims of the patent
will not be read restrictively unless the patentee has
demonstrated a clear intention to limit the claim scope us-
ing ‘words or expressions of manifest exclusion or re-
striction.’” (quoting Teleflex, Inc. v. Ficosa N. Am. Corp.,
299 F.3d 1313, 1327 (Fed. Cir. 2002))). Therefore, we con-
clude that disclosing only the Probelec XB 7081 embodi-
ment, without more, does not result in a clear disavowal of
claim scope.
     Additionally, distinguishing the double desmear pro-
cess as “contrary to” or “in stark contrast” with the single
desmear process, which again appears within the context
of disclosures of the preferred embodiment, are not clear
and unmistakable limiting statements. We have held that
“[m]ere criticism of a particular embodiment . . . is not suf-
ficient to rise to the level of clear disavowal.” Thorner, 669
F.3d at 1366. Thus, comparing and contrasting the present
14            CONTINENTAL CIRCUITS LLC v. INTEL CORPORATION




technique to that of the prior art does not “rise to the level
of [a] clear disavowal” of claim scope. Id.
     Similarly, the descriptions of “the present invention,”
which also appear within the discussion of the preferred
embodiment, are not limiting here. While descriptions “of
the ‘present invention’ as a whole” could limit the scope of
the invention, see Verizon Servs. Corp. v. Vonage Holdings
Corp., 503 F.3d 1295, 1308 (Fed. Cir. 2007), “use of the
phrase ‘present invention’ or ‘this invention’ is not always
so limiting, such as where the references . . . are not uni-
form, or where other portions of the intrinsic evidence do
not support applying the limitation to the entire patent,”
Absolute Software, Inc. v. Stealth Signal, Inc., 659 F.3d
1121, 1136–37 (Fed. Cir. 2011). In this case, the state-
ments that “the present invention can be carried out by a
new use” of a dielectric material called Probelec XB 7081,
see ’582 patent col. 6 ll. 41–48 (emphasis added), and “the
present invention differs from the common desmear process
in that sub-steps in the desmear process are repeated as a
way of forming the teeth,” id. col. 8 ll. 49–52 (emphases
added), do not characterize the present invention “as a
whole,” Verizon, 503 F.3d at 1308. Instead, they disclose
one way to carry out the present invention using Probelec
XB 7081, and references to “the present invention” occur
within this context.
     Moreover, the use of “the present invention” through-
out the specification does not uniformly require use of a re-
peated desmear process. See Absolute Software, 659 F.3d
at 1136–37. In certain portions of the specification, such
as the summary, the invention is described with respect to
its “unique surface structure,” ’582 patent col. 1 l. 52, with-
out any requirement that the invention must encompass
the repeated desmear process. In fact, “desmear” does not
appear in the summary of the invention section at all. See
id. col. 1 l. 48–col. 2 l. 29. In light of this, it is difficult to
say that the present invention “as a whole,” Verizon, 503
F.3d at 1308, necessarily includes the repeated desmear
CONTINENTAL CIRCUITS LLC v. INTEL CORPORATION             15



process. Thus, absent “clear and unmistakable” language
suggesting otherwise, we conclude that the aforementioned
statements do not meet the “exacting” standard required to
limit the scope of the claims to a repeated desmear process.
See Thorner, 669 F.3d at 1366–67.
    The district court also found that the prosecution his-
tory further supported its claim construction. Similar to
disclaimers in the specification, “[t]o operate as a dis-
claimer, the statement in the prosecution history must be
clear and unambiguous, and constitute a clear disavowal of
scope.” Verizon, 503 F.3d at 1306. We do not agree that
such a clear disavowal exists in this prosecution history.
The expert declaration cited by the district court, which the
applicants relied on to respond to both the indefiniteness
and the written description rejections, explained that the
written description disclosed “a technique which forms the
teeth” by “performing two separate swell and etch steps.”
J.A. 2074 ¶ 7 (citing ’582 patent col. 9 ll. 1–9) (emphasis
added). The district court found this statement “clearly de-
scribe[d] the patented method as involving two etching pro-
cesses.” See Claim Construction Order, 2017 WL 3478659,
at *6. But clearly describing a particular claim term to
overcome an indefiniteness or written description rejection
is not the same as clearly disavowing claim scope. Moreo-
ver, the statements in the expert declaration merely ex-
plain one technique for forming teeth and do not amount to
clear statements of disavowal. We therefore conclude that
the cited statements in the prosecution history do not
clearly and unmistakably disavow any claim scope.
    Before we conclude our analysis of the intrinsic evi-
dence, we note that in order to read a process limitation
into a product claim, it must meet one more criterion. Gen-
erally, “[a] novel product that meets the criteria of patent-
ability is not limited to the process by which it was made.”
Vanguard Prods. Corp. v. Parker Hannifin Corp., 234 F.3d
1370, 1372–73 (Fed. Cir. 2000). “However, process steps
can be treated as part of a product claim if the patentee has
16           CONTINENTAL CIRCUITS LLC v. INTEL CORPORATION




made clear that the process steps are an essential part of
the claimed invention.” Andersen Corp. v. Fiber Compo-
sites, LLC, 474 F.3d 1361, 1375 (Fed. Cir. 2007). For the
same reasons that the statements relied upon by the dis-
trict court do not show that the patentee clearly and un-
mistakably disavowed claim scope, they also do not make
clear that the repeated desmear process is “an essential
part” of the claimed electrical device having a tooth struc-
ture. Id. Far from being essential, the statements from the
intrinsic evidence merely indicate a preference for using
Probelec XB 7081 and include comparisons with the prior
art techniques. Because the patentee has not “made clear”
that the repeated desmear process is “an essential part of
the claimed invention,” id., it was improper for the district
court to read this process limitation into the product claims
for this additional reason.
    Finally, secondary to the intrinsic evidence, “we have
also authorized district courts to rely on extrinsic evidence,
which ‘consists of all evidence external to the patent and
prosecution history, including expert and inventor testi-
mony, dictionaries, and learned treatises.’” Phillips, 415
F.3d at 1317 (quoting Markman, 52 F.3d at 980). But
“while extrinsic evidence ‘can shed useful light on the rele-
vant art,’” id. (quoting C.R. Bard, Inc. v. U.S. Surgical
Corp., 388 F.3d 858, 862 (Fed. Cir. 2004)), it is “less signif-
icant than the intrinsic record in determining the ‘legally
operative meaning of disputed claim language,’” C.R. Bard,
388 F.3d at 862 (quoting Vanderlande Indus. Nederland
BV v. Int’l Trade Comm’n, 366 F.3d 1311, 1318 (Fed. Cir.
2004)); see also Phillips, 415 F.3d at 1317. Generally, we
have viewed extrinsic evidence as “less reliable” than in-
trinsic evidence. Phillips, 415 F.3d at 1318.
    Here, the district court acknowledged that the extrinsic
evidence, which consisted of documents authored by the in-
ventors, was “not reliable enough to be dispositive,” but
“provide[d] helpful corroboration.” See Claim Construction
Order, 2017 WL 3478659, at * 6. The inventor documents
CONTINENTAL CIRCUITS LLC v. INTEL CORPORATION             17



state that the inventors used “two passes through
desmear,” J.A. 3321, and a “double pass desmear” J.A.
3324, to achieve the tooth structure. However, similar to
the intrinsic evidence, those statements reflect use of the
preferred embodiment but give the public no indication
that they have any limiting effect. Because we have al-
ready determined that the intrinsic evidence does not sup-
port reading a repeated desmear process into the claims,
the “less reliable” extrinsic evidence, Phillips, 415 F.3d at
1318, which even the district court acknowledged was “not
reliable enough to be dispositive,” see Claim Construction
Order, 2017 WL 3478659, at * 6, does not counsel other-
wise. Accordingly, we conclude that the Category 1 Terms
should not be limited to requiring a repeated desmear pro-
cess and should be given their plain and ordinary meaning.
                       CONCLUSION
    For the foregoing reasons, we conclude that the district
court erred in reading a “repeated desmear process” limi-
tation into the Category 1 Terms. Because the parties stip-
ulated to noninfringement based on the court’s erroneous
construction, we vacate the judgment of noninfringement
and remand for further proceedings.
             VACATED AND REMANDED
