Nitto Denko Corp. v. Hutchinson Technology Incorporated

1. Case Identification

• Case #: IPR2018-01300
• Patent #: 8,169,746
• Filed: July 31, 2018
• Petitioner(s): Nitto Denko Corp.
• Patent Owner(s): Hutchinson Technology Inc.
• Challenged Claims: 7-9, 11, and 15

2. Patent Overview

• Title: Integrated Lead Suspension with Multiple Trace Configurations
• Brief Description: The ’746 patent relates to a hard drive suspension flexure that uses different electrical trace configurations in different regions. The design purports to address the need for traces with high bandwidth, low impedance, and low stiffness by using distinct trace structures, such as interleaved or stacked traces in one region and ground plane traces in another.

3. Grounds for Unpatentability

Ground 1: Anticipation of Claims 7 and 11 - Claims 7 and 11 are anticipated by Balakrishnan under 35 U.S.C. §102.

• Prior Art Relied Upon: Balakrishnan (Patent 6,038,102).
• Core Argument for this Ground:
  • Prior Art Mapping: Petitioner argued that Balakrishnan discloses every limitation of claims 7 and 11. Balakrishnan teaches an integrated lead suspension flexure for a hard disk drive with a gimbal and tail region. It describes a "first region" (trace/film segment 62) having a first trace configuration of interleaved traces (electromagnetically-coupled passive conductors). It also describes a "second region" (the portion on the flexure) having a second, different trace configuration of ground plane traces (traces formed on a conductive steel layer). Petitioner asserted these two trace sections are electrically connected to form a continuous signal path, thus anticipating the independent claims.

Ground 2: Obviousness of Claims 7 and 11 - Claims 7 and 11 are obvious over Balakrishnan in view of Young.

• Prior Art Relied Upon: Balakrishnan (Patent 6,038,102) and Young (Patent 5,717,547).
• Core Argument for this Ground:
  • Prior Art Mapping: This ground was presented as an alternative, should the Board find that Balakrishnan's electromagnetically-coupled "passive" interleaved traces do not meet the "interleaved traces" limitation. Petitioner contended that Young teaches an integrated transmission line array using interleaved two-terminal "active" traces, which could be substituted into the Balakrishnan design. Balakrishnan provides the base flexure with distinct trace regions, and Young supplies the specific teaching of two-terminal interleaved traces.
  • Motivation to Combine: A POSITA would combine these references because Balakrishnan explicitly incorporates Young by reference to address the problem of improving electrical characteristics in a flexure's trace array. Young’s design, using two-terminal conductors, is narrower and allows interleaving to be implemented on smaller portions of the flexure, a known design goal.
  • Expectation of Success: A POSITA would have had a reasonable expectation of success because swapping Balakrishnan's passive interleaved array for Young's active array was a routine design choice between known, functionally equivalent options for reducing inductance.

Ground 3: Obviousness of Claims 9 and 15 - Claims 9 and 15 are obvious over Balakrishnan in view of Yuuki.

• Prior Art Relied Upon: Balakrishnan (Patent 6,038,102) and Yuuki (Application # 2006/0203372).

• Core Argument for this Ground:

  • Prior Art Mapping: This ground addressed the additional limitations in claims 9 and 15 related to impedance matching. Petitioner argued that while Balakrishnan teaches the base flexure and the desirability of tuning impedance, Yuuki explicitly teaches how to achieve impedance matching along a transmission line in a hard drive. Yuuki discloses constructing a transmission line from segments of varying impedance to match the driver's impedance at one end to the magnetic head's impedance at the other, which is the same technique claimed in the ’746 patent.
  • Motivation to Combine: A POSITA, having read Balakrishnan's disclosure on the benefits of tuning impedance, would have been motivated to consult known art for implementation details. Impedance matching was a notoriously old and well-known principle for improving electrical performance. Yuuki provided an exemplary and directly applicable method for achieving this in the same technical context.
  • Expectation of Success: Success was predictable because the combination involved applying a fundamental electrical engineering principle (impedance matching) as taught by Yuuki to the known flexure structure of Balakrishnan to achieve the well-understood benefit of optimized energy transfer.

• Additional Grounds: Petitioner asserted additional obviousness challenges, including a ground that claims 8 and 11 are obvious over Balakrishnan, Balakrishnan ’152 (Patent 5,737,152), and Young. This ground argued for replacing Balakrishnan's interleaved traces with the "stacked traces" taught in Balakrishnan ’152, another known alternative for reducing inductance. A further ground combined Balakrishnan, Yuuki, and either Young or Balakrishnan ’152 to teach the use of bond pads for impedance-matched connections.

4. Key Claim Construction Positions

• "Interleaved": Petitioner argued this term should be given its plain and ordinary meaning: arranging parts of sequences so they alternate while each retains its identity. This broad construction was central to the argument that Balakrishnan's structure, which uses passive conductive traces alternating with active signal traces, meets the limitation without needing to be modified by another reference.
• "ground plane trace": Petitioner asserted this is a well-understood term for a trace backed by an electrically conductive layer, which could be the underlying spring metal of the flexure itself. This construction was necessary to map the second trace region of Balakrishnan, which features traces on a conductive steel flexure, to the claim language.

5. Arguments Regarding Discretionary Denial

• Petitioner argued that discretionary denial under §325(d) would be inappropriate. It was noted that the primary prior art references (Balakrishnan, Young, Balakrishnan ’152) were cited in an Information Disclosure Statement (IDS) during prosecution of the ’746 patent. However, Petitioner contended that these references were not substantively addressed or analyzed by the examiner, and therefore the PTO had not previously considered the specific invalidity arguments presented in the petition.

6. Relief Requested

• Petitioner requested the institution of an inter partes review and the cancellation of claims 7-9, 11, and 15 of Patent 8,169,746 as unpatentable.