PTAB

IPR2018-00954

Nitto Denko Corp v. Hutchinson Technology Inc

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Petition
petition

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 hard disk drive suspension with a crossover structure for its electrical traces. To reduce signal crosstalk, the invention discloses a "non-continuous first trace" that allows a "second trace" to cross over it, with certain embodiments using a "conductive island" formed in the support layer to electrically connect the segments of the non-continuous trace.

3. Grounds for Unpatentability

Ground 1: Claims 1-4, 11-15, and 22 are Anticipated by Young; 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: Petitioner argued that Young, which teaches interleaved trace interconnect structures for hard drive suspensions, discloses every limitation of independent claims 1 and 12. Young describes a laminated suspension with a conductive support layer, an insulating layer, and multiple traces designed to cross over each other to reduce noise. Petitioner mapped one set of Young's interleaved traces (60A/60B), which are physically separated but connected by bridging paths, to the claimed "non-continuous first trace." Another set of traces (62A/62B) was mapped to the "second trace," which crosses the first at the point of physical separation while remaining electrically isolated. For the dependent claims requiring a "conductive island" in the support layer to connect the non-continuous trace segments, Petitioner asserted that Asami teaches this exact feature. Asami discloses a printed wiring board where an island formed in a lower metal layer connects segments of an upper trace via through-holes to facilitate a crossover.
    • Motivation to Combine: Petitioner contended that a person of ordinary skill in the art (POSITA) would combine Young and Asami. Young expressly suggests that "other bridge interconnect paths and devices may be employed" to create its crossovers, directly inviting the consideration of known alternatives. Asami's conductive island was a well-known, routine design choice for this purpose. A POSITA would be motivated to use Asami's simpler technique to reduce the manufacturing complexity and cost associated with Young's alternative embodiment that uses separate dielectric layers for bridging paths.
    • Expectation of Success: A POSITA would have had a high expectation of success in making this combination. Both Young and Asami describe structurally similar multi-layer devices (a lower conductive layer, an intermediate insulator, and upper traces) and both contemplate using vias to connect different layers, making the integration of Asami's island into Young's flexure predictable.

Ground 2: Claims 1-4 and 12-15 are Anticipated by Carpenter; Claims 5-6, 9-10, 16-17, and 20-21 are Obvious over Carpenter in view of Asami

  • Prior Art Relied Upon: Carpenter (WO 98/20485) and Asami (Japanese Application # S61-26283).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner asserted that Carpenter, which teaches an integrated suspension and conductor structure, anticipates independent claims 1 and 12. Carpenter's design repeatedly crosses two traces by forming trace segments on two different dielectric layers connected by vias. Petitioner argued this structure meets the limitations of a "non-continuous first trace" (composed of segments on the upper and lower layers) being crossed by a "second trace." For the dependent claims requiring a conductive island in the support layer, Petitioner again relied on Asami to supply this limitation, arguing it teaches forming crossover connections in the main support layer itself rather than on a separate dielectric layer as in Carpenter.
    • Motivation to Combine: The primary motivation asserted was to simplify Carpenter's complex five-layer structure (support layer, lower dielectric, lower traces, upper dielectric, upper traces). A POSITA would recognize that Carpenter's design was unnecessarily complicated and would be motivated to apply Asami's teachings to eliminate the separate lower dielectric and trace layers. This modification would transform Carpenter's five-layer structure into a more efficient three-layer structure, significantly reducing material costs and simplifying manufacturing steps.
    • Expectation of Success: Success was expected because both references disclose multi-layer circuit structures, and the use of a conductive support layer for electrical routing was a well-understood and common practice in the art. The result—a functional crossover—was highly predictable.
  • Additional Grounds: Petitioner asserted an additional obviousness challenge for claims 11 and 22 over Carpenter alone, arguing that achieving an "equal number of crossover points" was a simple and obvious design choice for ensuring electrical symmetry and simplifying manufacturing connections.

4. Key Claim Construction Positions

  • Petitioner argued for the plain and ordinary meaning of the term "non-continuous first trace." The central aspect of their proposed construction was that the term requires a physical break in the first trace at the crossover point, which ensures it remains electrically isolated from the second trace at that specific location. This construction is critical to their anticipation arguments, as it would read on prior art like Young where the segments of the "non-continuous" trace are connected elsewhere by other means (e.g., a trace bridge at the end of the trace line).

5. Relief Requested

  • Petitioner requested institution of an inter partes review and cancellation of claims 1-6, 9-17, and 20-22 of the ’750 patent as unpatentable.