During patent drafting, careful consideration of the terminology can prevent overly limiting claim constructions at a later point, and many experienced practitioners have come to realize that a fair amount of lawyering and wordsmithing is required to ensure that an invention is not limited to only those embodiments disclosed in an application. The Federal Circuit has consistently taken the approach that the intrinsic evidence contained within the patent is most highly regarded during claim construction, to the point where inventor statements characterizing the invention may be irrelevant. In Continental Circuits LLC v. Intel Corp., (Appeal Number 2018-1076, Fed. Cir. February 8, 2019) (“Continental Circuits”), the Federal Circuit looked at a limitation that was read into the claims by the District Court and found that the exacting requirements to infer a claim limitation had not been met.

Continental Circuits LLC (“Continental”) owned four patents directed to a “multilayer electrical device… having a tooth structure.” Continental Circuits at 2. The four patents at issue, U.S. Patent No. 7,501,582 (“the ‘582 patent”), U.S. Patent No. 8,278,560 (“the ‘560 patent”), U.S. Patent No. 8,581,105 (“the ‘105 patent”), and U.S. Patent No. 9,374,912 (“the ‘912 patent”), disclose a solution to the common problem of delamination in electric device construction and usage that occurs in printed circuit boards. See the ‘582 patent at column 1, lines 28-46. When combining multiple conductive and dielectric layers, delamination, blistering, and other separation issues between layers can arise during the construction and use of such electric devices (e.g., due to thermal stress). Id.

To reduce these issues, the ‘582, ’560, ‘105, and ‘912 patents provide “a unique surface structure” that mechanically grips two layers together and prevents delamination. The ‘582 patent states: “it is still better to use teeth that are fang-shaped to enable a mechanical grip… By using the fanged, angled, canine, or otherwise hooked teeth… there is a multidirectional, three dimensional interlacing or overlapping of layers.” Id. at column 1, lines 58-66.

To form this layer, the ‘582, ’560, ‘105, and ‘912 patents propose using “a dielectric material [having] a non-homogeneous composition or thickness to bring about an uneven chemical resistance” that forms teeth during etching, instead of providing a uniform etch, Id. at column 2, lines 25-30, and the patents describe a “swell and etch” or “desmear” process that may be used to form the teeth. However, unlike the prior art, the patents propose a “double desmear” process in order to form the teeth, id. at column 5, lines 40-46, and the ‘582 patent described the double desmear process and its benefits as follows:

…[E]xcept that contrary to all known teachings in the prior art, in effect, a “double desmear process” is utilized. That is, not merely increasing the times and temperatures and other parameters for the desmear process, but instead completing the process a first time, and then completing the process a second time.” Id.

Accordingly the peel strength produced in accordance with the present invention is greater than the peel strength produced by the desmear process of the prior art, i.e., a single pass desmear process. Id. at column 7, lines 3-9.

Continental sued Intel Corporation, its supplier Ibiden U.S.A. Corporation, and the supplier’s parent company Ibiden Co. Ltd. (collectively “Intel”) for infringement of the ‘582, ’560, ‘105, and ‘912 patents. The key element of dispute between Continental and Intel was whether Continental had limited the etching or desmear process (that provides for the generation of the teeth on a layer) to a repeated or “double desmear” process. See Continental Circuits at 4. In particular, the District Court found that the claim limitations should be limited to a repeated desmear process.

To make its construction, the District Court first looked at intrinsic evidence for claim construction within the patent history. Id. at 7. They found that the specification repeatedly distinguished the “double desmear” process described in the patent from the prior art single etching or desmear processes. Id. Additionally, the prosecution history included an expert declaration that stated that “the ‘etching’ process disclosed in the specification uses ‘this known Probelec XB[] 7-81 resin’ and ‘two separate swell and etch steps’ as ‘a technique which forms the teeth.’” Id. at 7-8. Furthermore, additional extrinsic evidence of statements by the inventors that they use a “two pass desmear cycle”, and that “we use a double pass desmear to achieve the tooth structure” was found persuasive in findin that the claims required a double desmear process. Thus, the District Court held that “Intel had ‘met the exacting standard required’ to read a limitation into the claims.” Id. at 7.

Exacting Requirements for Clear Disavowal of Claim Scope – Drafting and Prosecution Techniques

On appeal, Continental argued that “the plain language of the claims does not include a repeated desmear process,” and that “the specification does not clearly and unmistakably limit the claims to require a repeated desmear process.” Id. at 9. Continental argued that although the patent discussed a preferred embodiment using a repeated desmear process, the language of the patent did not limit the invention to only this embodiment. Id. In response, Intel contended that it was clear that “the patentees repeatedly disparaged and disavowed the single-pass desmear process, and expressly defined ‘the present invention’ [in the patent] as requiring a repeated desmear.” Id. Intel further argued that this was supported by the prosecution history’s expert declaration stating that “the claimed invention is directed to surface roughening performed by ‘two separate’ passes of a desmear process.” Id. at 10.

The Federal Circuit agreed with Continental that none of the intrinsic or extrinsic evidence met the high burden in a manner required to read a limitation into a claim. Id. at 10. In finding this, the Federal Circuit referred to the main tenets of claim construction found in Phillips v. AWH Corp. 415 F.3d 1303 (Fed. Cir. 2005) and Markman v. Westview Instruments 517 U.S. 370 (1996). The Federal Circuit proceeded to review the specification to determine whether either the patentee had “act[ed] as its own lexicographer”, or performed “an intentional disclaimer, or disavowal, of claim scope.” Continental Circuits at 11-12. Although the Federal Circuit noted the “difficulty in drawing the ‘fine line between construing the claims in light of the specification and improperly importing a limitation from the specification into the claims,’” the Federal Circuit did not find that any of the statements in the specification rose to the level of a “clear and unmistakable disclaimer.” Id. at 12.

The Federal Circuit examined the specification and found that statements such as “[o]ne technique for forming the teeth” was the double desmear process in contrast to those known in the art, that “the present invention can be carried out by a new use,” and that “[f]or example, the present invention differs… as a way of forming the teeth”, were insufficient to introduce a limitation into the claims. Id. Furthermore, statements such as “that the peel strength produced… is greater than that of ‘the prior art,’” indicated that the patent merely described a preferred embodiment and the patentee did not intend to clearly limit claim scope. Id. at 12-13. The court stated “[h]eeding the warning in Phillips… 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.” Id. at 13. Thus, disclosure of only a single embodiment does not disavow claim scope without “words or expressions of manifest exclusion or restriction.” Id.

For experienced patent prosecution practitioners, this type of language is second nature to include when drafting patents, and the Federal Circuit appears to support the position that the use of such legal techniques and terminology in application drafting can provide additional claim scope and expand an invention further than what the inventors originally disclosed or imagined (as evidenced by the statements of the inventors in the extrinsic evidence in this case). The Federal Circuit also noted that statements regarding the “double desmear” process as “contrary to” or “in stark contrast” with the single desmear process also did not present “clear and unmistakable limiting statements.” Id. Merely comparing and contrasting with the prior art does not disavow claim scope, nor do descriptions of “the present invention.” Id. at 14. For example, the Federal Circuit found that “the use of ‘the present invention’ through the specification does not uniformly require use of a repeated desmear process,” noting that the term “desmear” did not even appear in the summary of the invention. Id. at 14.

However, describing “the present invention” contrasts with many often-followed principles of modern patent application drafting. For example, in Verizon Service Corp. v. Vonage Holdings Corp., the Federal Circuit stated “[w]hen a patent thus describes the features of the ‘present invention’ as a whole, this description limits the scope of the invention.” 503 F.3d 1295, 1308 (Fed. Cir. 2007). There, the Federal Circuit stated “[i]n the course of describing the ‘present invention,’ the specification then states that ‘[t]he gateway compresses and decompresses voice frequency communication signals and sends and receives the compressed signals in packet form via the network.” Id. This served to be a limiting issue. However, in Verizon, the patent at issue begins by stating “the present invention” and the “inventive system,” while later referring to preferred embodiments within the summary of the invention. See column 4, lines 6-33 of U.S Patent No. 6,359,880. This limiting description, as well as wording in the “Disclosure of the Invention” (i.e., the summary of the invention), may be the cause of this appearance of inconsistency in Federal Circuit claim construction rulings.

With regard to the prosecution history, the Federal Circuit did not find a disclaimer in the description of the process of “a technique which forms the teeth.” Continental Circuits at 15. The court explained, “clearly describing a particular claim term to overcome an indefiniteness or written description rejection is not the same as clearly disavowing claim scope”, characterizing that explanation as only one technique, and not the only technique available for desmear. Id. Instead, because the patentees had not made it clear that it was essential that the repeated desmear process was part of “a product claim,” reading “a process limitation into a product claim” was improper. Id. at 15-16.

Regarding the extrinsic evidence that included documents authored by the inventors that stated that the inventors had utilized “two passes through desmear” and a “double desmear process,” the Federal Circuit found that “those statements reflect use of the preferred embodiment but give the public no indication that they have any limiting effect.” Id. at 16-17. The extrinsic evidence merely “confirm[ed] that their alleged invention was limited to a repeated desmear process,” which confirmed that the District Court improperly read a limitation into the claims. Id. As the Federal Circuit stated in another case, “[u]ltimately, the only meaning that matters in claim construction is the meaning in the context of the patent.” Poly-America, L.P. v. API Industries, Inc., 839 F.3d 1131, 1137 (2016). As such, this extrinsic evidence was insufficient to limit the claims from the broader terminology utilized when drafting and prosecuting the patents, which reflects the care and nuances of patent legalese that should be considered when characterizing an invention in a patent application.