DCT

0:17-cv-01992

Hutchinson Technology Inc v. Nitto Denko Corp

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I. Executive Summary and Procedural Information

  • Parties & Counsel:
  • Case Identification: 0:17-cv-01992, D. Minn., 06/12/2017
  • Venue Allegations: Venue is alleged to be proper for Nitto Denko Corporation as a foreign entity and for Nitto, Inc. based on its established place of business within the district and the occurrence of infringing acts in Minnesota.
  • Core Dispute: Plaintiff alleges that Defendant’s hard disk drive (HDD) suspension components, known as "flexures," infringe ten U.S. patents related to various aspects of flexure design, manufacturing, and electrical performance.
  • Technical Context: The technology concerns flexures, which are critical micro-components within HDD suspension assemblies that hold the read/write head over the magnetic disk, manage electrical signals, and ensure mechanical stability.
  • Key Procedural History: The complaint alleges a duopolistic market where Plaintiff was a first-mover and Defendant entered later. To support claims of pre-suit knowledge and willfulness, the complaint alleges that Defendant cited several of the patents-in-suit as prior art during the prosecution of its own U.S. and foreign patents.

Case Timeline

Date Event
1996-06-24 Priority Date for ’807 Patent
1996-08-07 Priority Date for ’758 Patent
1998-01-01 Nitto enters flexure technology field
1999-03-16 U.S. Patent No. 5,883,758 Issues
1999-08-31 Priority Date for ’183 Patent
1999-09-28 U.S. Patent No. 5,959,807 Issues
2001-04-16 Priority Date for ’385 Patent
2001-09-25 U.S. Patent No. 6,295,183 Issues
2002-04-25 Priority Date for ’499 Patent
2004-03-30 U.S. Patent No. 6,714,385 Issues
2004-06-16 Priority Date for ’750 Patent
2005-05-16 Priority Date for ’438 Patent
2005-09-09 Priority Date for ’679 Patent
2005-11-15 U.S. Patent No. 6,965,499 Issues
2006-03-07 Priority Date for ’866 Patent
2008-03-11 U.S. Patent No. 7,342,750 Issues
2008-04-08 Priority Date for ’746 Patent
2008-12-23 U.S. Patent No. 7,468,866 Issues
2009-05-12 U.S. Patent No. 7,532,438 Issues
2010-08-24 U.S. Patent No. 7,781,679 Issues
2012-05-01 U.S. Patent No. 8,169,746 Issues
2014-07-01 Nitto allegedly has knowledge of ’499 Patent
2016-01-01 Plaintiff purchases HDDs with accused flexures
2017-06-12 Complaint Filed

II. Technology and Patent(s)-in-Suit Analysis

U.S. Patent No. 6,714,385 - Apparatus And Method Of Controlling Common Mode Impedance In A Disk Drive Head Suspension

Issued March 30, 2004

The Invention Explained

  • Problem Addressed: In HDD suspensions, the underlying metal support structure acts as a ground plane that affects the electrical properties of the signal-carrying traces. Specifically, it influences both "differential mode impedance" (related to signal integrity) and "common mode impedance" (related to noise rejection). Prior art methods of etching "windows" into the ground plane to control these properties often forced a trade-off between the two (’385 Patent, col. 1:7-22).
  • The Patented Solution: The invention introduces electrically isolated conductive "islands" or "doors" within the windows of the ground plane (’385 Patent, Abstract). By adjusting the size and placement of these islands relative to the windows, it becomes possible to adjust the common mode impedance independently of the differential mode impedance, allowing for simultaneous optimization of noise suppression and signal integrity (’385 Patent, col. 2:25-44).
  • Technical Importance: This innovation provided designers with a more sophisticated tool to manage the complex electrical environment of a high-speed data interconnect, a critical factor in improving data transfer rates and reliability in smaller, denser HDDs (’385 Patent, col. 2:42-44).

Key Claims at a Glance

  • The complaint asserts at least Claim 3, which depends on independent Claim 1 (Compl. ¶61, 65, 67).
  • Independent Claim 1 requires:
    • A trace and load beam assembly for controlling common mode impedance.
    • A load beam formed of a conductive layer.
    • At least one aperture in the conductive layer.
    • A conductive island in the at least one aperture.
    • The island is electrically isolated from the conductive layer of the load beam.
  • The complaint reserves the right to assert other claims (Compl. ¶57).

U.S. Patent No. 6,965,499 - Head Suspension Configured For Improved Thermal Performance During Solder Ball Bonding Of Slider

Issued November 15, 2005

The Invention Explained

  • Problem Addressed: Electrically connecting a head slider to the suspension's traces using solder balls is an advantageous manufacturing process. However, the heat from this process can cause the solder to shrink upon cooling, creating mechanical stress and distortion in the delicate suspension components near the bonding region, which can degrade the performance of the head suspension (’499 Patent, col. 1:53-61).
  • The Patented Solution: The invention proposes structures that mechanically and thermally isolate the solder bonding pads from the main support structure of the flexure. This is achieved by methods such as removing the underlying spring metal layer beneath the pads (creating cantilevered pads), adding serpentine "strain relief portions" to the traces near the pads, or increasing the conductive material of the pads to dissipate heat more effectively (’499 Patent, col. 2:25-52).
  • Technical Importance: By mitigating the thermal distortion associated with solder ball bonding, the invention enabled manufacturers to use this preferable bonding method without compromising the precise mechanical characteristics of the suspension, leading to improved manufacturing yields and more reliable HDDs (’499 Patent, col. 2:1-11).

Key Claims at a Glance

  • The complaint asserts at least Claim 12 (Compl. ¶76, 80, 82).
  • Independent Claim 12 requires:
    • A flexure with a slider bonding region on a stainless steel layer.
    • Electrical traces including bonding pads adjacent to the slider bonding region.
    • A support structure for the bonding pads designed to "reduce mechanical and thermal effects of a solder ball bonding process."
  • The complaint reserves the right to assert other claims (Compl. ¶57).

U.S. Patent No. 5,959,807 - Head Suspension With Motion Restraining Tethers

Issued September 28, 1999

  • Technology Synopsis: The patent describes a head suspension where the region carrying the read/write head is connected to the support region by a compliant area. To prevent damage from shock or impact, "tethers" made of a low-stiffness material connect the two regions to restrain movement to a limited range without compromising normal operation (’807 Patent, Abstract). (Compl. ¶89).
  • Asserted Claims: At least Claim 12 (Compl. ¶94, 96, 98).
  • Accused Features: Nitto's flexures incorporated into suspension assemblies in HDDs manufactured by Hitachi Global Storage Technologies are alleged to infringe (Compl. ¶99).

U.S. Patent No. 5,883,758 - Lead Structure With Stainless Steel Base For Attachment To A Suspension

Issued March 16, 1999

  • Technology Synopsis: The patent discloses a lead structure for an HDD head suspension formed from a laminated sheet with a copper conductor layer and a stainless steel base layer. The base layer has mounting sections with tabs for welding to the suspension, while portions of the conductor layer that traverse flexible regions of the suspension are free from the metal base layer to maintain flexibility (’758 Patent, Abstract). (Compl. ¶103).
  • Asserted Claims: At least Claim 1 (Compl. ¶105, 109, 111).
  • Accused Features: Nitto's flexures incorporated into HDDs manufactured by Toshiba are alleged to infringe (Compl. ¶114).

U.S. Patent No. 8,169,746 - Integrated Lead Suspension With Multiple Trace Configurations

Issued May 1, 2012

  • Technology Synopsis: The patent describes an integrated lead suspension flexure with different electrical trace configurations in different regions to optimize performance. For example, it may use "interleaved traces" in the tail region and "ground plane traces" in the gimbal region, with transition structures to connect them and match impedance between the different sections (’746 Patent, Abstract). (Compl. ¶118).
  • Asserted Claims: At least Claim 7 (Compl. ¶120, 124, 126).
  • Accused Features: Nitto's flexures incorporated into HDDs manufactured by Hitachi Global Storage Technologies are alleged to infringe (Compl. ¶129).

U.S. Patent No. 7,342,750 - Method For Providing Electrical Crossover In A Laminated Structure

Issued March 11, 2008

  • Technology Synopsis: The patent discloses a method for creating an electrical crossover in a laminated suspension. One electrical trace is made non-continuous, with a gap where a second trace crosses over. A conductive "island area" patterned into the underlying support layer electrically bridges the gap in the first trace, allowing it to pass "under" the second trace without a direct physical connection (’750 Patent, Abstract). (Compl. ¶133).
  • Asserted Claims: At least Claim 1 (Compl. ¶135, 139, 141).
  • Accused Features: Nitto's flexures incorporated into HDDs manufactured by Seagate Technology LLC are alleged to infringe (Compl. ¶144).

U.S. Patent No. 7,532,438 - Wireless Flexures With Curved Trace Geometry Against Pitch and Roll Adjustment Springback

Issued May 12, 2009

  • Technology Synopsis: The patent addresses the problem of "springback" after adjusting the pitch and roll of a flexure, where mechanical stresses cause it to return partially to its original shape. The solution involves using curvilinear or serpentine trace geometries, which can deflect and absorb the strains from adjustment, preventing the accumulation of stress that causes springback (’438 Patent, Abstract). (Compl. ¶148).
  • Asserted Claims: At least Claim 5 (Compl. ¶152, 154, 156).
  • Accused Features: Nitto's flexures incorporated into HDDs manufactured by Toshiba are alleged to infringe (Compl. ¶157).

U.S. Patent No. 6,295,183 - Wireless Disk Drive Suspension With Optimized Mechanical and Electrical Properties

Issued September 25, 2001

  • Technology Synopsis: The patent describes a way to reduce unwanted capacitive coupling between signal conductors and the underlying wireless conductor (ground plane) in a suspension. This is achieved by removing only the portion of the wireless conductor immediately opposite the signal conductors, which increases the dielectric path length and improves electrical properties without sacrificing the mechanical support provided by the rest of the conductor layer (’183 Patent, Abstract). (Compl. ¶161).
  • Asserted Claims: At least Claim 1 (Compl. ¶165, 167, 169).
  • Accused Features: Nitto's flexures incorporated into HDDs manufactured by Seagate Technology LLC are alleged to infringe (Compl. ¶170).

U.S. Patent No. 7,781,679 - Disk Drive Suspension Via Formation Using A Tie Layer And Product

Issued August 24, 2010

  • Technology Synopsis: The patent discloses a method for creating a strong, low-resistance electrical connection (a "via") between a conductive layer (e.g., copper traces) and a grounding layer (e.g., stainless steel). It uses a "tie layer" (e.g., chromium) deposited through an aperture in the insulating layer, which promotes strong bonding between the grounding layer and a subsequently deposited conductor that fills the via (’679 Patent, Abstract). (Compl. ¶174).
  • Asserted Claims: At least Claim 1 (Compl. ¶176, 179, 181).
  • Accused Features: Nitto's flexures incorporated into suspension assemblies in HDDs manufactured by Seagate Technology LLC are alleged to infringe (Compl. ¶184).

U.S. Patent No. 7,468,866 - Flexible Printed Circuit For head Gimbal Assembly

Issued December 23, 2008

  • Technology Synopsis: The patent describes a flexible printed circuit (FPC) for a head gimbal assembly that includes multiple traces connecting the slider to a conductive tab and a separate test tab. A key feature is a dedicated grounding trace that grounds the FPC at the test tab, which helps protect the sensitive read/write head from electrostatic discharge (ESD) during manufacturing and testing (’866 Patent, Abstract). (Compl. ¶188).
  • Asserted Claims: At least Claim 1 (Compl. ¶190, 193, 195).
  • Accused Features: Nitto's flexures incorporated into suspension assemblies in HDDs manufactured by Toshiba are alleged to infringe (Compl. ¶198).

III. The Accused Instrumentality

Product Identification

The accused instrumentalities are "flexures," which are components of suspension assemblies used within hard disk drives (HDDs) (Compl. ¶4, 42). The complaint identifies flexures manufactured and sold by Nitto that are incorporated into HDDs sold by third parties, including Seagate Technology, Hitachi Global Storage Technologies, and Toshiba (Compl. ¶70, 85, 114).

Functionality and Market Context

Flexures are flexible circuits that provide the electrical pathway between the HDD's read/write head slider and the drive's electronics (Compl. ¶4). They must be mechanically robust enough for manufacturing but flexible enough to allow the head to move precisely across the spinning disk. The complaint alleges that Plaintiff HTI and Defendant Nitto are the "only two flexure suppliers of significance world-wide," and that Nitto holds approximately an 80% share of the flexure market (Compl. ¶47).

IV. Analysis of Infringement Allegations

No probative visual evidence provided in complaint.

The complaint alleges infringement but incorporates detailed claim charts by reference in an Exhibit K, which was not provided with the complaint filing (Compl. ¶57). In lieu of a claim chart summary, the narrative infringement theories are summarized below.

'385 Patent Infringement Allegations

The complaint alleges that Nitto's flexures, as found in certain Seagate HDDs, contain an apparatus for controlling common mode impedance that meets the limitations of at least claim 3 of the ’385 Patent (Compl. ¶61, 70). The core of this allegation is that the accused flexures utilize a ground plane layer with apertures that contain electrically isolated conductive islands to independently manage common mode and differential mode impedance (Compl. ¶59). A potential point of contention may be a factual dispute over whether the accused products actually contain structures that meet the definition of an "electrically isolated" "conductive island" as required by the claims.

'499 Patent Infringement Allegations

The complaint alleges that Nitto's flexures, as found in certain Hitachi HDDs, are configured for improved thermal performance during solder ball bonding in a manner that infringes at least claim 12 of the ’499 Patent (Compl. ¶76, 85). The allegation centers on the assertion that the accused flexures include a support structure specifically designed to mechanically and thermally isolate the bonding region from the slider mounting region to reduce distortion (Compl. ¶74). A likely point of contention will be the construction of the term "reduce mechanical and thermal effects," and whether the specific design of the accused products achieves a level and type of reduction that falls within the scope of the claims.

V. Key Claim Terms for Construction

Term from ’385 Patent, Claim 1: "a conductive island ... electrically isolated from the conductive layer"

  • Context and Importance: This term describes the central novel feature of the patent. The outcome of the infringement analysis for the ’385 Patent may depend entirely on whether features within Nitto's flexures are found to be "conductive islands" that are "electrically isolated."
  • Intrinsic Evidence for a Broader Interpretation: The specification may support a broad interpretation by describing the island simply as a portion of conductive material located within an aperture that is not in electrical contact with the main conductive layer (load beam) that surrounds the aperture (’385 Patent, col. 2:25-31).
  • Intrinsic Evidence for a Narrower Interpretation: Embodiments shown in the patent's figures (e.g., FIG. 4, item 18) and related descriptions may depict the islands with specific shapes, sizes, or a particular spatial relationship to the traces. A defendant may argue these specific examples limit the term to structures that mirror those embodiments, rather than any isolated piece of conductive material.

Term from ’499 Patent, Claim 12: "a support structure for supporting the bonding pads to reduce mechanical and thermal effects"

  • Context and Importance: This is a functional limitation that is critical to the infringement question for the ’499 Patent. The dispute will likely focus on what type of structure meets this functional requirement and what degree of "reduction" is necessary.
  • Intrinsic Evidence for a Broader Interpretation: The patent's summary describes multiple ways to achieve this function, including reducing the support structure, adding strain relief portions, or increasing the conductive material of the pads (’499 Patent, col. 2:31-44). A plaintiff may argue that a structure performing any of these functions, or an equivalent function, meets the limitation.
  • Intrinsic Evidence for a Narrower Interpretation: A defendant may argue that the claim requires more than an incidental or trivial reduction in thermal effects. They could point to specific embodiments, such as the cantilevered configuration or U-shaped slits (’499 Patent, Abstract; col. 4:25-34), to argue that the term should be construed to require a structure that provides a significant and intentional level of mechanical and thermal isolation, not merely any design that happens to be less rigid than a fully supported pad.

VI. Other Allegations

Indirect Infringement

The complaint alleges that Nitto induced infringement by marketing its flexures to HDD manufacturers, providing instructions on how to incorporate them into HDDs, and sharing technical information, with the knowledge and intent that these customers would directly infringe (Compl. ¶49, 53). Contributory infringement is alleged on the basis that the flexures are especially made for an infringing use and are not staple articles of commerce with substantial non-infringing uses (Compl. ¶56).

Willful Infringement

The willfulness allegations are based on alleged pre-suit knowledge of the patents. The complaint asserts that Nitto was aware of the patents because it cited several of them as prior art in Information Disclosure Statements during the prosecution of its own patents (Compl. ¶77, 136, 177, 191). This is presented as direct evidence of pre-suit knowledge of the patents and the technology they cover. The complaint also puts Nitto on notice for post-suit conduct as of the filing date (Compl. ¶51).

VII. Analyst’s Conclusion: Key Questions for the Case

  • A central issue will be one of technical evidence: does forensic analysis of the accused Nitto flexures reveal the presence of the specific micro-structures claimed in the patents, such as the "electrically isolated" "conductive islands" of the '385 patent or the functionally-defined thermal "isolation" structures of the '499 patent?
  • A key legal question will be one of willful conduct: given the specific allegations that Nitto cited multiple asserted patents during its own patent prosecution, what was the extent of its pre-suit knowledge, and does this evidence demonstrate the kind of deliberate or egregious conduct that could lead to a finding of willfulness and enhanced damages?
  • The case may also hinge on claim construction: how will the court define the scope of key terms that are central to the infringement analysis across the ten asserted patents, and will those definitions be broad enough to read on the accused products or narrow enough to allow for a finding of non-infringement?