Hutchinson Technology Incorporated v. Nitto Denko Corporation

1. Case Identification

• Case #: Inter Partes Review No. not assigned
• Patent #: 7,923,644
• Filed: June 16, 2017
• Petitioner(s): Hutchinson Technology Incorporated, Hutchinson Technology Operations (Thailand) Co., Ltd.
• Patent Owner(s): Nitto Denko Corp.
• Challenged Claims: 1-4 and 6

2. Patent Overview

• Title: PRINTED CIRCUIT BOARD AND METHOD FOR MANUFACTURING SAME
• Brief Description: The ’644 patent relates to a printed circuit board for hard disk drive suspensions and a corresponding manufacturing method. The core technology involves using interleaved wiring patterns, where traces from one signal pair are located between traces of another, to reduce characteristic impedance at a low cost.

3. Grounds for Unpatentability

Ground 1: Claims 1-2 and 6 are anticipated by Rice

• Prior Art Relied Upon: Rice (Patent 8,169,746)
• Core Argument:
  • Prior Art Mapping: Petitioner argued that Rice, which discloses an integrated lead head suspension flexure, teaches every limitation of independent claims 1 and 6, as well as dependent claim 2. Rice allegedly shows a printed circuit board with an insulating layer, two pairs of interleaved wiring patterns on one surface, and electrode pads connected to those patterns. Petitioner mapped the claimed "first connecting layer" to Rice's "spring metal island 82," which is located on the opposite side of the insulating layer and connects portions of a wiring pattern through vias. The specific branched line configurations and intersection regions required by claim 1 were also asserted to be disclosed. Method claim 6 was argued to be anticipated because Rice describes conventional manufacturing processes, such as photolithography and etching, sufficient to produce the anticipated structure of claim 1.

Ground 2: Claims 3-4 are obvious over Rice

• Prior Art Relied Upon: Rice (Patent 8,169,746)
• Core Argument:
  • Prior Art Mapping: Petitioner contended that while Rice discloses a "first connecting layer," it does not explicitly teach the "second connecting layer" required by dependent claim 3. However, Petitioner argued it would be obvious to substitute the crossover structure shown in Rice's Figure 4 (which uses a spring metal island) for the other transition structures in the design, thereby creating a second, identical connecting layer.
  • Motivation to Combine: The primary motivation was design simplicity and manufacturing efficiency. A person of ordinary skill in the art (POSITA) would find it a predictable choice to use the same crossover design for both required intersections. Furthermore, using the Figure 4 island structure for both crossovers would keep all electrode connections on a single plane, simplifying fabrication compared to the multi-plane structure in Rice's Figure 2. Rice’s own specification suggests using alternative transition structures, further motivating this modification.
  • Expectation of Success: A POSITA would have a high expectation of success because both transition structures in Rice perform the same function of allowing interleaved traces to intersect. Substituting one known, functional structure for another was presented as a simple and predictable design choice with a clear path to success.

Ground 3: Claims 1-4 and 6 are obvious over Young in view of Yang

• Prior Art Relied Upon: Young (Patent 5,717,547), Yang (Patent 7,342,750)
• Core Argument:
  • Prior Art Mapping: Petitioner asserted that Young teaches the basic structure of a printed circuit board flexure with interleaved wiring patterns on an insulating layer, but lacks a specific crossover mechanism that uses a connecting layer on the opposite side. Yang was introduced to supply this missing element, as it explicitly teaches a crossover feature for hard disk drive suspensions that uses a "conductive island area" on the opposite side of an insulating layer, connected via through-holes, to allow planar traces to cross over each other.
  • Motivation to Combine: A POSITA, seeing the need for a crossover or "bridge interconnect path" as mentioned in Young, would be motivated to consult known solutions in the same field. Yang provided a known, efficient, and cost-effective method for creating such a crossover. Combining Yang’s specific implementation with Young’s general layout was argued to be a predictable design choice to solve a known problem in the art.
  • Expectation of Success: The combination was asserted to be predictable and likely to succeed because both references address the same technology (hard disk drive suspensions) and the same problem (routing interleaved traces). A POSITA would reasonably expect that implementing Yang's well-understood crossover structure into Young's design would successfully create a functional, interleaved circuit as claimed.

4. Key Claim Construction Positions

• Petitioner proposed a construction for the term "connecting layer" as "a conductive layer that is part of the suspension body that allows electrical connection." This construction was argued to be consistent with the ’644 patent’s specification, which identifies a region of the suspension body as an example of the connecting layer. This interpretation was critical to Petitioner's arguments for mapping the "spring metal island" of Rice and the "conductive island area" of Yang to this claim limitation.

5. Arguments Regarding Discretionary Denial

• Petitioner argued that institution would not be redundant with a previously filed IPR (IPR2017-01499) against the same ’644 patent. It was asserted that the current petition relies on entirely different prior art (Rice, Young, and Yang), whereas the earlier petition was based on different references (Contreras and Pro). Petitioner contended this presented new questions of patentability for the Board to consider, making discretionary denial under §325(d) inappropriate.

6. Relief Requested

• Petitioner requested institution of an inter partes review for each ground presented and cancellation of claims 1-4 and 6 of the ’644 patent as unpatentable.