Dissenting opinion filed by Circuit Judge Newman.
Wallach, Circuit Judge.
Appellant Knowles Electronics, LLC ("Knowles") appeals the inter partes reexamination decision on appeal of the U.S. Patent and Trademark Office's ("USPTO") Patent Trial and Appeal Board ("PTAB") affirming an examiner's rejection of claims 1-4 of U.S. Patent No. 6,781,231 ("the '231 patent") for anticipation and proposed claims 23-27 for lack of an adequate written description.1 Cirrus Logic, Inc. v. Knowles Elecs. LLC (Cirrus I ), No. 2015-004342, 2015 WL 5272691, at *2-3 (P.T.A.B. Sept. 8, 2015) ; see Cirrus Logic, Inc. v. Knowles Elecs. LLC (Cirrus II ), No. 2015-004342, 2016 WL 1378707, at *1-2 (P.T.A.B. Apr. 5, 2016) (denying request for rehearing).
Knowles appeals. We have subject matter jurisdiction pursuant to 28 U.S.C. § 1295(a)(4)(A) (2012). We affirm.
BACKGROUND
The '231 patent, entitled "Microelectromechanical System Package with Environmental *1361and Interference Shield," discloses microelectromechanical system ("MEMS") packages comprising a substrate, a microphone, and a cover accommodating the microphone. '231 patent, Abstract. The MEMS packages shield the microphone from an interference signal or an environmental condition, id. col. 1 ll. 38-41, and purportedly improve over the prior art's drawbacks "associated with manufacturing these housings, such as lead time, cost, and tooling," id. col. 1 ll. 30-32.
The instant appeal concerns claims 1-4 and proposed claims 23-27 of the '231 patent. Independent claim 1 is illustrative of the invention and recites:
A microelectromechanical system package comprising:
a microelectromechanical system microphone;
a substrate comprising a surface for supporting the microelectromechanical microphone;
a cover comprising a conductive layer having a center portion bounded by a peripheral edge portion; and
a housing formed by connecting the peripheral edge portion of the cover to the substrate, the center portion of the cover spaced from the surface of the substrate to accommodate the microelectromechanical system microphone, the housing including an acoustic port for allowing an acoustic signal to reach the microelectromechanical system microphone wherein the housing provides protection from an interference signal.
Id. col. 5 ll. 12-25 (emphasis added). Claims 2-4 also recite a "package." See id. col. 5 ll. 26, 39, 53. Proposed claims 23-27 recite a package with a "lower surface comprising a plurality of solder pads" that is "configured to mechanically attach and electrically connect the [MEMS] package" to a printed circuit board "using a solder reflow process ." J.A. 3886 (emphasis added); see J.A. 3886-87.
DISCUSSION
Knowles raises three primary arguments on appeal. First, Knowles argues that "the [PTAB]'s rejection of the potentially most commonly accepted definition of 'package,' and corresponding invalidity finding, requires reversal" as to claims 1-4. Appellant's Br. 45 (capitalization and alterations omitted); see id. at 45-63.2 Second, Knowles argues that "the [PTAB]'s written description analysis requires reversal" as to the PTAB's rejection of proposed claims 23-27. Id. at 63 (capitalization and alterations omitted); see id. at 63-74. Finally, Knowles contends that "the record does not establish that the [Appellees] are proper parties." Id. at 75 (capitalization omitted); see id. at 75-79. After articulating the applicable standard of review and legal standards, we address Knowles's arguments in turn.
I. Claim Construction in Claims 1-4
A. Standard of Review and Legal Standard
"We review the [PTAB]'s ultimate claim construction in a reexamination de novo." In re CSB-Sys. Int'l, Inc. , 832 F.3d 1335, 1340 (Fed. Cir. 2016) (citing, inter alia, Teva Pharm. USA, Inc. v. Sandoz, Inc. , --- U.S. ----, 135 S.Ct. 831, 840-41, --- L.Ed.2d ---- (2015) ). A patent's specification, together with its prosecution *1362history,3 constitutes intrinsic evidence to which the PTAB gives priority when it construes claims. See Microsoft Corp. v. Proxyconn, Inc. , 789 F.3d 1292, 1297-98 (Fed. Cir. 2015). We review the PTAB's assessment of intrinsic evidence de novo. See id. When the PTAB "look[s] beyond the patent's intrinsic evidence and ... consult[s] extrinsic evidence," such as expert testimony, dictionaries, and treatises, Teva , 135 S.Ct. at 841, those underlying findings amount to factual determinations that we review for "substantial evidence," Microsoft Corp. , 789 F.3d at 1297 (citation omitted). Substantial evidence means such "relevant evidence [that] a reasonable mind might accept as adequate to support a conclusion." Consol. Edison Co. v. NLRB , 305 U.S. 197, 229, 59 S.Ct. 206, 83 L.Ed. 126 (1938) (citations omitted). "If the evidence in record will support several reasonable but contradictory conclusions," we "will not find the [PTAB's] decision unsupported by substantial evidence simply because the [PTAB] chose one conclusion over another plausible alternative." In re Jolley , 308 F.3d 1317, 1320 (Fed. Cir. 2002).
"During reexamination proceedings of unexpired patents ... the [PTAB] uses the broadest reasonable interpretation [ ('BRI') ] consistent with the specification standard ...." In re CSB-Sys. , 832 F.3d at 1340 (internal quotation marks and citation omitted); cf. Cuozzo Speed Techs., LLC v. Lee , --- U.S. ----, 136 S.Ct. 2131, 2144-45, 195 L.Ed.2d 423 (2016) (acknowledging the PTAB's use of BRI during reexamination). "Accordingly, this court reviews the reasonableness of the [US]PTO's disputed claim term interpretations." In re Bigio , 381 F.3d 1320, 1324 (Fed. Cir. 2004) (internal quotation marks and citation omitted). However, "[e]ven under the [BRI], the [PTAB's] construction cannot be divorced from the specification and the record evidence ... and must be consistent with the one that those skilled in the art would reach." Microsoft Corp. , 789 F.3d at 1298 (internal quotation marks and citations omitted).
B. The PTAB Properly Construed the Term "Package" in Claims 1-4
Knowles makes several arguments for why the PTAB's construction of "package" in the preamble of claim 1 of the '231 patent is incorrect.4 The PTAB found that, under the BRI, a "package" "may refer to chip assemblies that possess any type of second-level connection mechanism." Cirrus I , 2015 WL 5272691, at *11 ; see Cirrus II , 2016 WL 1378707, at *4 ("[T]he Panel explained why the [BRI] of 'package' included, but was not limited to , packages produced from [Knowles's] two [proposed] mounting methods." (citation omitted) ).5 On appeal, Knowles contends *1363that the term "package" should be construed to mean an assembly that "requires a second-level connection with a mounting mechanism." Appellant's Br. 47. Thus, Knowles disagrees with the PTAB's construction, which does not limit the "connection" to one that uses a "mounting mechanism."6
Claims 1-4 do not specify the type of connection required to form the MEMS package. See '231 patent col. 5 ll. 12-67. The '231 patent's specification similarly does not limit the type of connection to one that is mountable or any specific form of mount. See, e.g. , id. col. 3 ll. 4-7 ("The embodiment disclosed herein ... would typically be mounted ...." (emphasis added) ), col. 3 ll. 19-20 (describing the package to include "surface mountable components" without detailing the means of required connection with an external mechanism), col. 4 ll. 3-4 (describing general "electrical connection" of the substrate). Moreover, the parties do not identify any disclosures in the prosecution history that would aid in the construction of the term.
Because intrinsic evidence is not definitive, we turn to extrinsic evidence. See Phillips , 415 F.3d at 1319 (allowing courts to look to extrinsic evidence after reviewing intrinsic evidence to better understand the field of the invention and the meaning of a term to a PHOSITA). Knowles asks the court to look only at certain dictionary and treatise references describing common categories for mounting in MEMS to form second-level connections. See Appellant's Br. 50-52. However, as the PTAB correctly noted, many references suggested by Knowles use qualifying language, thereby implying second-level connections in circuit boards may not be properly limited to the two types of mounts proffered by Knowles. See Cirrus I , 2015 WL 5272691, at *11 (quoting Fundamentals of Microsystems Packaging 67 (Rao R. Tummala ed., 2001) (J.A. 2833) ("In general , ... packages can be classified into two categories: 1) through-hole, and 2) surface mount.") (emphasis added) ); id. (quoting Microelectronics Packaging Handbook 42 (Rao R. Tummala et al. eds., 1989) (J.A. 2847) ("There are two basic types of connections ....") (emphasis added) ); id. (quoting Handbook of Electronic Package Design 4 (Michael Pecht ed., 1991) (J.A. 2842) ("The external connections of a chip carrier serve to classify the component into one of the two major technological categories ....") (emphasis added) ). Moreover, Knowles provided additional extrinsic evidence that supports the PTAB's determination that a package need not be confined to certain *1364types of second-level connection mounts. See Cirrus I , 2015 WL 5272691, at *11-12 (reviewing Electronic Industries Alliance JEDEC Standard defining package as "[a]n enclosure ... that allows electrical connection and provides mechanical and environmental protection" (J.A. 637-38), and a technical dictionary definition defining package as, inter alia, "an enclosure ... used to contain any level of electronic system or subsystem" (J.A. 642-43) ).
Knowles does not contest that the references cited by the PTAB allow for means of connectivity beyond surface and through-hole mounts. Instead, Knowles argues that the PTAB impermissibly "simply select[ed] the broadest definition" cited by the parties to arrive at its claim construction. Appellant's Br. 55 (quoting PPC Broadband, Inc. v. Corning Optical Commc'ns RF, LLC , 815 F.3d 747, 752 (Fed. Cir. 2016) ). That is incorrect. The PTAB reviewed all extrinsic evidence, including evidence proffered by Knowles, and found no evidence that the definition was limited to surface or through-hole mounting. Unlike PPC Broadband , where the PTAB failed to consider evidence "in light of the specification" and "claims themselves," 815 F.3d at 752, Knowles admitted that the claims and specification did not offer a definition for package that would inform a PHOSITA as to its favored interpretation, see J.A. 4152 ("[The '231 patent ] ... does not offer a concise dictionary definition of the term."), 6907 (similar). Therefore, the PTAB properly considered extrinsic evidence, and we see no error in the PTAB's claim construction based on this extrinsic evidence.
Knowles additionally argues that "[t]he [PTAB] should have read MEMS Technology and concluded that a 'package' requires a 'self-contained unit['] ... and that this unit must be 'mountable.' " Appellant's Br. 53 (citing MEMS Tech. Berhad v. Int'l Trade Comm'n , 447 Fed.Appx. 142 (Fed. Cir. 2011) ). This is so, Knowles avers, because the PTAB has an obligation to "evaluate a previous judicial interpretation of disputed claims 'and to determine whether it is consistent with the [BRI] of the term.' " Id. at 59 (alteration omitted) (quoting Power Integrations, Inc. v. Lee , 797 F.3d 1318, 1327 (Fed. Cir. 2015) ). We disagree with the premise of Knowles's argument suggesting that the PTAB's claim construction conflicts with MEMS Technology . In MEMS Technology , we upheld the International Trade Commission's construction of the term "package" in the '231 patent's preamble to mean "a self-contained unit that has two levels of connection, to the device and to a circuit (or other system)." 447 Fed.Appx. at 159 ; see id. (affirming the ITC's rejection of an anticipation claim because the disputed prior art "does not disclose first and second levels of electrical connection"). Thus, the claim construction in MEMS Technology did not require that a package be mounted via surface or through-hole mounts, such that even if we were to look to MEMS Technology , we would find no inconsistency with the PTAB's construction of the claim term "package" here.
Further, Knowles argues that this court's construction in MEMS Technology differed from the PTAB's below because in MEMS Technology we stated "[t]he requirement that the components listed in the claim body come together to form a mountable package is ... an important characteristic of the claimed invention." Id. at 154 (internal quotation marks and citation omitted); see Appellant's Br. 59-61. We made this statement in the context of finding that the preamble was a claim limitation, see Catalina Mktg. , 289 F.3d at 808 (stating preambles may be limiting if they "recit[e] additional structure or steps underscored as important by the specification"), not in the context of construing the *1365term's disputed meaning. Later in the opinion, we applied the ITC's construction that a package "is a self-contained unit that has two levels of connection, to the device and to a circuit (or other system)." MEMS Tech. , 447 Fed.Appx. at 159. "We will not find legal error based upon an isolated statement stripped from its context." VirnetX Inc. v. Apple Inc. , 665 Fed.Appx. 880, 886 (Fed. Cir. 2016). We fail to see how the definition of package adopted by the PTAB below does not accord with the definition adopted in MEMS Technology . Neither definition limited the two levels of connection to surface or through-hole mounting. In sum, we find that the PTAB properly construed the claim term "package."
II. Written Description in Proposed Claims 23-27
"The [PTAB]'s determination that a patent claim is unpatentable for insufficient written description support is a question of fact that we review for substantial evidence." Blue Calypso, LLC v. Groupon, Inc. , 815 F.3d 1331, 1344 (Fed. Cir. 2016). According to 35 U.S.C. § 112 ¶ 1 (2006),7 "[t]he specification shall contain a written description of the invention, and of the manner and process of making and using it, in such full, clear, concise, and exact terms as to enable any [PHOSITA] to which it pertains ... to make and use the same." The written description "must clearly allow [a PHOSITA] to recognize that the inventor invented what is claimed." Ariad Pharm., Inc. v. Eli Lilly & Co. , 598 F.3d 1336, 1351 (Fed. Cir. 2010) (en banc) (internal quotation marks and brackets omitted). "[A] description which renders obvious a claimed invention is not sufficient to satisfy the written description requirement of that invention." Regents of the Univ. of Cal. v. Eli Lilly & Co. , 119 F.3d 1559, 1567 (Fed. Cir. 1997). "[T]he hallmark of written description is disclosure. ... [T]he test requires an objective inquiry into the four corners of the specification from the perspective of a [PHOSITA]." Ariad , 598 F.3d at 1351.
B. Substantial Evidence Supports the PTAB's Lack of Adequate Written Description Determination as to Proposed Claims 23-27
Proposed claims 23-27 of the '231 patent recite a MEMS package wherein the solder pads are "configured to mechanically attach and electrically connect the package to a surface of an external printed circuit board using a solder reflow process." J.A. 3886; see J.A. 3886-87. The PTAB determined that proposed claims 23-27 failed to meet the written description requirement, because "the present [s]pecification merely discloses a genus-solder pads that are capable of being connected to a board. But the [s]pecification fails completely to disclose the newly claimed species of such pads-pads that are connectable to a board specifically by using a reflow process." Cirrus I , 2015 WL 5272691, at *8. Knowles argues that the PTAB "fail[ed] to consider the extensive extrinsic and full intrinsic evidence" detailing how a PHOSITA would understand that solder pads were capable of attachment via reflow, Appellant's Br. 72; see id. at 71, and that the PTAB improperly considered "other methods of soldering" in its *1366analysis, id. at 73. We disagree with Knowles.
Substantial evidence supports the PTAB's determination that the specification does not provide adequate written description to allow a PHOSITA to recognize that the inventor invented what is claimed. As an initial matter, Knowles does not contend that the specification identifies the "solder reflow process" as a means of connecting solder pads to the circuit board. The '231 patent's specification states that the "substrate ... further comprises solder pads 31 for electrical connection to an end user's board." '231 patent col. 4 ll. 2-4. The specification's only other reference to solder pads states that "the leads are formed by plating a through-hole in a circuit board of which one half will eventually form the pathway to the solder pad." Id. col. 3 ll. 12-14. The specification thus does not require solder pads to connect to the circuit board by any particular process, including the solder reflow process. Moreover, Knowles does not contest that other processes for attaching solder pads were known in the art at the time of the invention and submitted as evidence before the PTAB, and those processes could have been used to form the complete circuit board according to the details in the specification. See Appellant's Br. 71-73 (recognizing other methods of soldering); J.A. 656-86, 2534-42 (same); see also Cirrus I , 2015 WL 5272691, at *7 ("We instead find that solder reflow is but one of multiple specific methods or species for connecting solder pads to a printed circuit board."). Substantial evidence thus supports the PTAB's determination that the '231 patent fails to provide adequate written description for the reflow process limitation.
Knowles's counterarguments are unpersuasive. First, Knowles contends that the PTAB disregarded "the state of the art at the time of filing" and "prior art knowledge" that would have demonstrated that a PHOSITA knew solder pads were "intended to be capable of reflow attachment to a user's board." Appellant's Br. 65, 66 (quoting Ariad Pharm. , 598 F.3d at 1358 ); see id. at 66-67 (listing prior art references that disclose solder reflow as a well-known process of connecting mount devices). Knowles misunderstands the PTAB's analysis. The PTAB acknowledged that solder reflow was a process of connecting a board to a solder pad but found that other processes of connection existed in the prior art. Therefore, the '231 patent's specification, detailing only the broad idea of solder pads connected to the circuit board, "fail[e]d completely to disclose the newly claimed species of such pads-pads that are connectable to a board specifically by using a reflow process." Cirrus II , 2016 WL 1378707, at *7 ; see Cirrus I , 2015 WL 5272691, at *8. The parties presented conflicting views of the knowledge of a PHOSITA and disputed whether such a person would have understood solder reflow to be the only (or even the primary) way to connect solder pads to a printed circuit board. Given these uncertainties and at best a passing reference to solder pads in the specification, the PTAB reasonably found that a PHOSITA would not have recognized that the inventor possessed solder pads "configured to" connect to a printed circuit board through a reflow process.
Second, Knowles states that the specification's description of the solder pads "on the bottom of the inventor's package" would make clear to a PHOSITA that the pads would necessarily attach to a user's board via solder reflow. Appellant's Br. 69; see id. at 68-70. The PTAB reviewed Knowles's arguments and found them unpersuasive because Knowles did not contend that the specification necessarily disclosed a solder reflow process. Cirrus I , 2015 WL 5272691, at *7 (citing J.A. 5199-201); see J.A. 5201 (stating, in Knowles's *1367brief to the PTAB, only that solder pads located on the bottom of the substrate "could use" the solder reflow process); see also Cirrus II , 2016 WL 1378707, at *6-7 (finding Knowles's arguments that solder pads "on the bottom" of the package would be used to mount a device through solder reflow "not persuasive" because, inter alia, the consideration for adequate written description asks what the applicant conveyed with reasonable clarity, and the '231 patent"failed to even mention, much less spell out any detail of, the claimed reflow process").
Knowles on appeal similarly fails to present evidence on the location of the pads sufficient to render the PTAB's findings unsupported. Knowles cites the single line of the specification disclosing solder pads generally, Appellant's Br. 69 (citing '231 patent col. 4 ll. 2-4), Figure 3 of the '231 patent showing the location of solder pads, id. , and a line from the specification that the inventor chose package elements to achieve "a better match of thermal coefficients," id. (quoting '231 patent col. 3 ll. 4-8). As we stated above, the single line disclosure of solder pads in the specification is insufficient to disclose the claimed solder reflow process. Moreover, the line discussing "thermal coefficients" relates to the material used for connecting the package to a circuit board and, without more, does not disclose any particular means of connection for the solder pads. Knowles cites to a line in the specification that the disclosed package will produce a "smaller" footprint than typical models that use a "gull wing configuration" because the "leads are formed by plating a through-hole in a circuit board of which one half will eventually form the pathway to the solder pad." '231 patent col. 3 ll. 12-16; see Appellant's Br. 69. Again, this description does not mention solder reflow, and Knowles has not presented evidence that through-hole plating is commonly understood to include solder reflow. See Appellant's Br. 50-52, 66-67 (distinguishing through-hole plating from surface mounting and arguing that solder reflow is a type of surface mounting). See generally id . For these reasons, we are not persuaded by Knowles's argument. See Lockwood v. Am. Airlines, Inc. , 107 F.3d 1565, 1572 (Fed. Cir. 1997) ("It is not sufficient for purposes of the written description requirement of § 112 that the disclosure, when combined with the knowledge in the art, would lead one to speculate as to the modifications that the inventor might have envisioned, but failed to disclose.").
Finally, Knowles alleges that the PTAB incorrectly required that the specification disclose a "process" of solder reflow for "apparatus claims." Appellant's Br. 73, 74. Knowles cites Microprocessor Enhancement Corp. v. Texas Instruments , to argue that the correct legal standard for finding an adequate written description of an apparatus claim asks only whether the apparatus is "capable of performing the recited functions." Id. at 74 (citing 520 F.3d 1367, 1375 (Fed. Cir. 2008) ). Knowles's cited portion of Microprocessor is not an analysis of the written description requirement under § 112 ; rather, it relates to whether a claim term used repeatedly in a patent's claims was "insolubly ambiguous," rendering the claims indefinite under the standard then applicable. 520 F.3d at 1374 ; see Nautilus, Inc. v. Biosig Instruments, Inc. , --- U.S. ----, 134 S.Ct. 2120, 2124, 189 L.Ed.2d 37 (2014) (describing change in the standard). These statements simply do not apply here.
Because the PTAB correctly identified and applied the applicable legal standard for lack of written description as recited by this court in Enzo Biochem, Inc. v. Gen-Probe Inc. , and its progeny, see Cirrus II , 2016 WL 1378707, at *6 (citing 323 F.3d 956, 969 (Fed. Cir. 2002), and explaining that "[t]he test for whether an applicant's *1368specification contains adequate written description for the claimed subject matter is whether applicant conveyed with reasonable clarity to those skilled in the art that, as of the filing date sought, applicant was in possession of the invention"); Cirrus I , 2015 WL 5272691, at *6-8 (discussing Enzo and subsequent written description cases), we see no reason to disturb the PTAB's holding on this basis.
III. Third-Party Requesters
The original petitions for inter partes reexamination in this case were filed by three third-party requesters. See Cirrus I , 2015 WL 5272691, at *1. Two of the three third-party requesters dropped out of the case on appeal. See Non-Participation Letter from Analog Devices, Inc., ECF No. 3; Change of Caption to Remove BSE Co., Ltd., ECF No. 18. The third, Wolfson Microelectronics plc. ("Wolfson"), was replaced by Cirrus Logic, Inc. and Cirrus UK Ltd. (together, "the Cirrus entities") as real parties-in-interest. See J.A. 14374-76 (Notice of Change in Real Party-in-Interest), 14418-20 (Supplemental Notice of Change in Real Party-in-Interest). Before the PTAB, the Cirrus entities were added as parties of record midway through proceedings but denied their request to participate in the oral hearing for the request to rehear Cirrus I based on untimely filing. J.A. 14434-41. The decision denying participation at the oral hearing further stated that, if the Cirrus entities chose to attend the hearing, the panel would have discretion to "ask [the Cirrus entities] any questions that they may have with regard to either the appeal or the Notice of Change in real party-in-interest." J.A. 14440.
In contesting the Cirrus entities' tardy request to participate in the oral hearing, Knowles, among other things, questioned whether the Cirrus entities were a proper party to the proceeding. J.A. 14409-14 (Opposition to Cirrus['s] Petition to Waive or Suspend Rules); see J.A. 14411 ("[The Cirrus entities'] filing does not explain how the Cirrus [e]ntities are entitled to take over for the Requester, Wolfson ...."). Although the PTAB did not allow the Cirrus entities to participate in the oral hearing based on their untimely filing, see J.A. 14439, the PTAB allowed the overall change in real party-in-interest for the case to proceed without comment.8 Before the PTAB, Knowles only contested the Cirrus entities' participation at the oral hearing, not the decision to add the Cirrus entities to the inter partes reexamination. See Oral Arg. at 19:57-20:10, http://oralarguments.cafc.uscourts.gov/default.aspx?fl=2016-2010.mp3 ("The best argument I have on that ... is I believe my client feels like it raised the objection below and at the first instance here on appeal we raised the objection."); see also id. at 18:53-19:23 ("[The Cirrus entities were not] permitted to participate at the oral argument. I guess our view was by that time we had prevailed on the issue of whether or not they could participate .... To us, it had been decided in our favor ... that seems like a decision on the merits ... that they weren't the proper party in the case."). Although Knowles now argues that it was not allowed to contest the entry of appearance below, id. at 18:23-52, *1369Knowles offers no evidence to support this statement. Only after the PTAB issued its decision on appeal and denial of a request for rehearing, and Knowles appealed to this court, did Knowles challenge the entry of the Cirrus entities as proper parties to the case. See Order, ECF No. 32 (denying Knowles's motion to remand the case for additional proceedings on the question of real parties-in-interest). As such, we find this argument waived.9 See Singleton v. Wulff , 428 U.S. 106, 120, 96 S.Ct. 2868, 49 L.Ed.2d 826 (1976).
CONCLUSION
We have considered Knowles's remaining arguments and find them unpersuasive. Accordingly, the Decision on Appeal of the U.S. Patent and Trademark Office's Patent Trial and Appeal Board is
AFFIRMED
COSTS
No costs.