2:23-cv-00539
E.D. Tex.May 27, 2025Background
- SK nexilis sued Solus/Volta asserting five patents (’541, ’090, ’689, ’014, ’706) directed to physical properties of electrolytic copper foil used in secondary (lithium) batteries; the Court held a Markman hearing on May 14, 2025.
- Disputed claim terms addressed measurement-based parameters (tensile strength, texture coefficient/TC, roughness Rz/RzJIS vs RzDIN, peak count/density, Rpc/PD), surface labels (matte/M vs shiny/S), a wrinkles limitation, and preamble scope.
- Defendants primarily argued many terms are indefinite because measurement choices (test temperature, XRD settings, profilometer choice, sampling location, standards) materially affect results.
- Plaintiff argued the terms have plain meanings or are definable by claim formulas/specification and industry standards; relied on expert testimony that a POSITA would know the appropriate test choices (e.g., peak area, JCPDS/ICDD standard, ambient temperature, ASME B46.1, JIS B 0601(2001)).
- The Court relied on intrinsic evidence (claims, specification, prosecution history) and extrinsic expert testimony, rejecting most indefiniteness challenges and supplying constructions where the specification provided definitions.
Issues
| Issue | Plaintiff's Argument | Defendant's Argument | Held |
|---|---|---|---|
| Tensile-strength claim ranges and measurement temperature | Plain meaning; room temperature measurement unless claim expressly requires heat treatment; UTM is standard | Indefinite because patents do not specify test temperature/method and battery use involves varied temperatures | Not indefinite; plain meaning. Where claim expressly recites heat treatment (’689), that test condition applies. |
| Texture coefficient (TC) formula / XRD-based TC ranges | TC is well-known and formula is in claims; POSITA would use industry norms (peak area, appropriate standard) | Indefinite due to test choices (peak height vs area, thin-film correction, slit size, sample orientation, choice of powder standard) | Not indefinite; plain meaning. Court relied on expert support that peak area and JCPDS/ICDD 04-0836 standard are appropriate; specification and prosecution history support certainty. |
| Surface roughness (Rz/Rz JIS/DIN, Rz/Ra ratios) | Plain meaning; where claim/spec defines RzJIS or cites JIS B 0601(2001) that governs measurement | Indefinite because of multiple Rz definitions (JIS1994 vs JIS2001/DIN), profilometer variability, sampling-location variability | Not indefinite. Court gave effect to explicit patent definitions (e.g., Rz = ten-point mean / RzJIS where specified; ’706 cites JIS B0601(2001) and provides measurement details). Measurement variability affects infringement fact issues, not definiteness. |
| Peak count (Pc) / peak count roughness (Rpc) / peak density (PD) | Plain meaning; where spec/claim defines Pc/Rpc/PD, those definitions control (ASME B46.1, 4 mm, ±0.5 µm, average of 3 points) | Indefinite due to sampling variability and lack of global reference length in some patents | Court adopted specification/claim lexicography: Pc/Rpc and PD construed as measured per ASME B46.1 with 4 mm length and ±0.5 µm criteria; not indefinite. Sampling variability is an infringement issue. |
| Matte/M vs Shiny/S surface labels | Plain, ordinary meaning (visual) | Need technical definition tied to manufacturing (to avoid jury confusion) | Court adopted specification-based definitions: shiny/S = surface that contacts electrode drum during electroplating; matte/M = opposite surface. |
| "so as to prevent the generation of wrinkles at a surface of the copper foil" | Means decrease or substantially prevent wrinkles (plain) | Should be read as requiring no wrinkles (as tested by Figure 1) or otherwise is indefinite | Court found prosecution statements and allowance history supported reading that no wrinkles are generated; construed to mean the surface has no wrinkles. |
| Preambles reciting "for a secondary battery" or "current collector" | Preambles are limiting because they state essential purpose/structure | Not limiting; body of claim is structurally complete and preamble is purposive | Preambles are not limiting. The Court applied the presumption against construing a stated purpose in the preamble as a claim limitation. |
Key Cases Cited
- Phillips v. AWH Corp., 415 F.3d 1303 (Fed. Cir. 2005) (claim terms construed from intrinsic evidence; specification is primary guide)
- Teva Pharm. USA, Inc. v. Sandoz, Inc., 574 U.S. 318 (2015) (district court may make subsidiary factual findings about extrinsic evidence in claim construction)
- Nautilus, Inc. v. Biosig Instruments, Inc., 134 S. Ct. 2120 (2014) (§112 requires claims inform skilled artisan of scope with reasonable certainty)
- Sonix Tech. Co. v. Publ’ns Int’l, Ltd., 844 F.3d 1370 (Fed. Cir. 2017) (indefiniteness must be proven by clear and convincing evidence)
- Dow Chem. Co. v. Nova Chems. Corp., 803 F.3d 620 (Fed. Cir. 2015) (indefiniteness where multiple reasonable methods yield materially different claim scopes and patent gives no guidance)
- Honeywell Int’l, Inc. v. U.S. Int’l Trade Comm’n, 341 F.3d 1332 (Fed. Cir. 2003) (indefiniteness where only confidential method produced claimed results)
- Presidio Components, Inc. v. Am. Tech. Ceramics Corp., 875 F.3d 1369 (Fed. Cir. 2017) (disputes over test application are infringement issues, not necessarily indefiniteness)
- Takeda Pharm. Co. v. Zydus Pharms. USA, Inc., 743 F.3d 1359 (Fed. Cir. 2014) (measurement variability alone does not render claim indefinite)
- SmithKline Beecham Corp. v. Apotex Corp., 403 F.3d 1331 (Fed. Cir. 2005) (indefiniteness test focuses on whether claim delineates bounds to skilled artisan, not on accused infringer's measurement ability)
- Omega Eng’g Inc. v. Raytek Corp., 334 F.3d 1314 (Fed. Cir. 2003) (prosecution disclaimer can limit claim scope)