PTAB

IPR2018-00954

Nitto Denko Corp. v. Hutchinson Technology Incorporated

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1. Case Identification

2. Patent Overview

  • Title: Method for Providing Electrical Crossover in a Laminated Structure
  • Brief Description: The ’750 patent relates to a laminated suspension for a hard disk drive that aims to reduce electrical signal crosstalk. The invention achieves this by employing a "non-continuous first trace" that is crossed by a second trace, with certain embodiments using a "conductive island" patterned into the underlying support layer to electrically connect the separated portions of the non-continuous trace.

3. Grounds for Unpatentability

Ground 1: Anticipation over Young - Claims 1-4, 11, 12-15, and 22 are anticipated by Young.

  • Prior Art Relied Upon: Young (Patent 5,717,547).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner argued that Young, which teaches "interleaved trace interconnect structures" for hard drive suspensions, discloses every limitation of the challenged independent claims. Young's structure includes multiple laminated layers (a steel flexure, an insulating layer, and copper traces) and interleaved traces that cross over each other to reduce signal degradation. Petitioner asserted that one of Young's interleaved traces (e.g., trace 60, composed of segments 60A and 60B) connected by a "bridging path" constitutes the claimed "non-continuous first trace," while another trace (e.g., trace 62) crosses over it, directly mapping to the limitations of independent claims 1 and 12. Dependent claims were also allegedly met, as Young's support layer ("flexure 14") is conductive stainless steel, and its structure has an equal number of crossover points for each trace.

Ground 2: Obviousness over Young in view of Asami - Claims 5-6, 9-10, 16-17, and 20-21 are obvious over Young in view of Asami.

  • Prior Art Relied Upon: Young (Patent 5,717,547) and Asami (Japanese Application # S61-26283).
  • Core Argument for this Ground:
    • Prior Art Mapping: This ground addressed the dependent claims requiring a "conductive island" to connect the parts of the non-continuous trace. While Young discloses the overall structure with crossing traces, it effectuates the crossover via "bridging paths." Asami was introduced because it explicitly teaches using a conductive island formed in a lower conductive layer of a printed wiring board to electrically connect interrupted upper trace portions, thereby facilitating a crossover. Petitioner contended that adding Asami's conductive island to Young's structure would result in the exact invention claimed.
    • Motivation to Combine: A Person of Ordinary Skill in the Art (POSITA) would combine these references for several reasons. First, Young expressly states that "other bridge interconnect paths and devices" could be used, inviting a POSITA to consider known alternatives like the one in Asami. Second, implementing the crossover using Asami’s conductive island method would be a routine design choice that simplifies manufacturing and reduces costs compared to adding separate bridging layers. Finally, other art (e.g., Roen, Patent 6,647,621) confirmed that using the lower steel layer of a suspension for signal transmission was a known and desirable technique.
    • Expectation of Success: A POSITA would have a high expectation of success. Both Young and Asami disclose structurally similar three-layer devices with conductive and insulating layers and contemplate using vias to connect layers. Applying Asami's well-understood connection method to Young's similar device was a simple substitution of one known element for another to produce a predictable result: a functional trace crossover.

Ground 3: Anticipation over Carpenter - Claims 1-4 and 12-15 are anticipated by Carpenter.

  • Prior Art Relied Upon: Carpenter (WO 98/20485).

  • Core Argument for this Ground:

    • Prior Art Mapping: Petitioner presented Carpenter as an alternative reference that anticipates the independent claims. Carpenter discloses an "integrated suspension and conductor structure" with "twisted" traces to reduce crosstalk. Its structure features trace links disposed on two different dielectric layers, connected by vias. Petitioner argued that a trace in Carpenter (e.g., trace 60) composed of separate segments on upper and lower layers is "non-continuous" as claimed. A second trace (trace 62) crosses over the first, thereby meeting all limitations of the independent claims. Petitioner noted that while both Young and Carpenter anticipate the claims, they do so with structurally different suspensions, making the grounds non-redundant.

  • Additional Grounds: Petitioner asserted that claims 11 and 22 are obvious over Carpenter, arguing it would have been an obvious design choice to use an equal number of crossover points for symmetry and ease of connection. Petitioner also argued that claims 5-6, 9-10, 16-17, and 20-21 are obvious over Carpenter in view of Asami, asserting a POSITA would be motivated to replace Carpenter's complex five-layer crossover structure with Asami's simpler three-layer conductive island approach to reduce manufacturing complexity and cost.

4. Key Claim Construction Positions

  • Petitioner contended that the term "non-continuous first trace" should be given its plain and ordinary meaning. This construction is central to the anticipation arguments, as Petitioner argued that the interrupted-and-reconnected trace structures in both Young (using bridging paths) and Carpenter (using vias between layers) meet this limitation. Petitioner noted that this limitation was added during prosecution to overcome prior art, but that Young and Carpenter, unlike the art of record, disclose functionally identical non-continuous structures.

5. Relief Requested

  • Petitioner requests institution of an inter partes review (IPR) and cancellation of claims 1-6, 9-17, and 20-22 of Patent 7,342,750 as unpatentable.