Cambridge Industries USA Inc v. Applied Optoelectronics Inc

1. Case Identification

• Case #: IPR2025-00436
• Patent #: 10,313,024
• Filed: January 17, 2025
• Petitioner(s): Cambridge Industries USA, Inc.
• Patent Owner(s): Applied Optoelectronics, Inc.
• Challenged Claims: 1-17

2. Patent Overview

• Title: Transmitter Optical Subassembly with Reduced Electrical Interference
• Brief Description: The ’024 patent describes a transmitter optical subassembly (TOSA) module designed to reduce electrical interference between power and radio frequency (RF) signals. The claimed invention achieves this by placing power and RF signal traces on opposing surfaces of both a main substrate and a feedthrough device that connects to a hermetically sealed light engine.

3. Grounds for Unpatentability

Ground 1: Claims 1-17 are anticipated by Mizobuchi under 35 U.S.C. § 102

• Prior Art Relied Upon: Mizobuchi (Patent 9,568,694).
• Core Argument for this Ground:
  • Prior Art Mapping: Petitioner argued that Mizobuchi discloses every limitation of the challenged claims. Mizobuchi teaches an optical module with a TOSA that includes a hermetically sealed light engine and a first circuit board (substrate) with opposing surfaces. Petitioner asserted that a Person of Ordinary Skill in the Art (POSITA) would understand from Mizobuchi’s disclosure of separate flexible printed circuits (FPCs) for high-speed RF signals and low-speed/DC power signals that these signals are carried on opposite surfaces of the circuit boards to achieve the claimed electrical isolation. Petitioner contended that Mizobuchi’s second circuit board and associated FPCs constitute the claimed "feedthrough device" that couples the laser packages to the driving circuit. For dependent claims, Petitioner argued Mizobuchi’s use of a removable FPC connector for power and a soldered FPC for RF signals meets the limitation of different interconnect types (claim 2), and that other features like DC busbars or wire bonds (claims 3-4) were well-known design choices.

Ground 2: Claims 1-17 are anticipated by Akashi under 35 U.S.C. § 102

• Prior Art Relied Upon: Akashi (Application # 2014/0140665).
• Core Argument for this Ground:
  • Prior Art Mapping: Petitioner argued that Akashi independently anticipates all challenged claims. Akashi discloses an optical subassembly with multiple TOSA modules, each containing a hermetically sealed light engine. Petitioner contended that Akashi explicitly teaches a flexible printed circuit with RF signal wires on one surface and DC voltage wires on the opposing surface to reduce noise, directly teaching the "opposing arrangement" limitation of claim 1. Petitioner mapped Akashi’s flexible printed circuit (130) and a portion of its receiver substrate (112) to the claimed "feedthrough device," arguing it couples the TOSA laser packages to the light engine driving circuit. For dependent claims, Petitioner asserted that a POSITA would have understood that various known connectors could be used (claim 2) and that adding ground traces (claim 5) was a standard technique for reducing crosstalk, as shown in Akashi’s Figure 4.

4. Key Claim Construction Positions

• "opposing arrangement": Petitioner argued this term, used interchangeably in the patent with "disposed opposite each other," is limited to disposing power and RF traces on opposite surfaces of a single circuit board or substrate. Petitioner contended that Patent Owner’s litigation position—that the term could cover traces on separate, adjacent circuit boards—is overly broad and inconsistent with the patent's disclosure.
• "feedthrough device" / "interconnect device": Petitioner asserted that these terms refer to the patterns and traces that propagate signals from external circuitry into the hermetically sealed package. Petitioner argued that Patent Owner’s proposed construction in district court litigation, which omits reference to the hermetic seal, is improperly expansive.

5. Arguments Regarding Discretionary Denial

• §325(d) Arguments: Petitioner argued that denial under 35 U.S.C. § 325(d) is inappropriate because the primary references, Mizobuchi and Akashi, were not cited or considered during the original prosecution of the ’024 patent. Therefore, the petition does not present the same art or arguments previously reviewed by the USPTO.
• Fintiv Arguments: Petitioner argued against discretionary denial under Fintiv, asserting that the parallel district court litigation is in a nascent stage. Key factors cited included: the trial date is scheduled for June 2026, well after the statutory deadline for a Final Written Decision (FWD); no claim construction hearing has occurred (scheduled for April 2025); and minimal investment has been made by the court and parties. Petitioner also stipulated that, if the IPR is instituted, it will not pursue invalidity in the district court based on the same grounds presented in the petition.

6. Relief Requested

• Petitioner requests institution of an inter partes review and cancellation of claims 1-17 of the ’024 patent as unpatentable.