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Justin E. Gray

IP Litigation Attorney at Foley & Lardner LLP

Former Adjunct Professor at Northwestern University School of Law

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BPAI Holds Term Indefinite and Summarizes Reasoning Behind Broadest Reasonable Interpretation Rule

Ex parte Senju Metal Industry Co. (BPAI Oct. 30, 2009)

The Board of Patent Appeals and Interferences ("BPAI"), in an opinion by Administrative Patent Judge Delmendo, affirmed a rejection of claims on reexamination relating to a soldering flux for soldering components.  At issue on appeal were rejections relating to indefiniteness, enlargement of claim scope, and obviousness. This post will focus on the indefiniteness rejection.

The patent examiner had held that the claim term "volatile organic solvent conventionally used in a soldering flux" was indefinite as the patent specification did not contain this language, "let alone any disclosure that would enlighten one skilled in the relevant art as to what solvents are covered by the [term]."  In response, the appellants submitted a declaration stating that a person skilled in the relevant art would understand "volatile" to mean "evaporating or passing off readily in the form of a vapor and that solvents in the [patent at issue] fall under this definition."  The appellants further stated that "[o]ne skilled in the art of preparing soldering fluxes would understand what solvents are conventionally used in soldering flux."

Before reaching the merits, the BPAI summarized the reasoning behind the broadest reasonable interpretation rule, stating "[t]his longstanding principle is based on the notion that 'during patent prosecution when claims can be amended, ambiguities should be recognized, scope and breadth of language explored, and clarification imposed.'  That is, a patent applicant has the opportunity and responsibility to remove any ambiguity in claim term meaning by amending the application.  'Only in this way can uncertainties of claim scope be removed, as much as possible, during the administrative process.'  '[A]s applicants may amend claims to narrow their scope, a broad construction during prosecution creates no unfairness to the applicant or patentee.'" (internal citations omitted).

Turning to the merits, the BPAI noted that the term "volatile organic solvent" does not appear in the patent specification.  Further, the appellants used the term in a "manner contrary to the ordinary meaning of the term" as they argued that ethylene glycol, which has a boiling point of 197°C, is covered by the claim term whereas a prior art patent used the term in a more conventional sense to exclude compounds with relativity high boiling points, for example furfuryl alcohol with a boiling point of about 170°C.  While "use of terms contrary to their ordinary meanings, in and of itself, does not render a claim indefinite, for [p]atentees are free to act as their own lexicographers … one skilled in the relevant art would not be able to ascertain whether an organic solvent with a boiling point of, e.g., 200°C would be covered by the disputed claim terms."  While "non-limiting examples of solvents suitable for the invention are listed" in the specification, the BPAI found that the specification "does not reasonably apprise the full scope of what Patentees mean by 'volatile organic solvent conventionally used in a soldering flux.'"

While, as noted above, the appellants submitted a declaration in support of a particular definition of "volatile", the BPAI found that this definition recited terms of degree like "rapidly" and "readily" on which the patent specification was silent. 

For these reasons, the BPAI affirmed the indefiniteness rejection.

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