PTAB

IPR2018-01483

Everlight Electronics Co Ltd v. Bridgelux Inc

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1. Case Identification

2. Patent Overview

  • Title: Efficient LED Array
  • Brief Description: The ’988 patent describes an LED apparatus where multiple LED chips are mounted directly onto a reflective metal substrate. The design creates separate horizontal electrical paths for current and vertical thermal paths for heat dissipation, improving efficiency.

3. Grounds for Unpatentability

Ground 1: Anticipation of Claims 1-9 by Sanpei

  • Prior Art Relied Upon: Sanpei (EP Publication # 1 895 602).
  • Core Argument: Petitioner argued that Sanpei, which discloses an LED array with nitride-based semiconductor chips, teaches every element of the challenged claims.
    • Prior Art Mapping: Petitioner asserted that Sanpei’s metal baseboard with a silver-plated reflective layer is the claimed "metal substrate having a reflective surface." Sanpei teaches mounting multiple LED chips directly onto this surface using an adhesive, creating an efficient thermal path into the substrate. The chips are spaced apart at intervals, exposing the reflective surface to reflect emitted light. Sanpei’s use of wire bonds and insulated conductor pads to connect the chips forms a horizontal, "chip to chip" electrical path that is electrically isolated from the metal substrate, meeting the limitations of independent claim 1 and its dependents covering specific materials (aluminum, silver plating), reflectivity (70%+), chip spacing (0.5mm+), and structural arrangements.

Ground 2: Anticipation of Claims 1, 3, 4, and 6-9 by Baek

  • Prior Art Relied Upon: Baek (Application # 2007/0075325).
  • Core Argument: Petitioner contended that Baek, which is directed to a high-power LED package, discloses all limitations of the specified claims by teaching an array of GaN LED chips mounted directly onto a reflective metal substrate.
    • Prior Art Mapping: Petitioner argued that Baek’s heat-dissipating base member, made of metal (e.g., copper) with a silver-plated reflective layer, meets the claimed substrate element. Baek discloses surface-mounting multiple LED chips directly onto this reflective layer. The chips are explicitly spaced apart within recesses to prevent light interference and allow reflection, creating separate thermal and electrical paths. The electrical path is formed horizontally via wire bonds connecting the top contacts of the chips, distinct from the vertical thermal path into the substrate, thus anticipating claim 1 and its relevant dependents.

Ground 3: Obviousness of Claims 1-9 over Ostler and Sanpei

  • Prior Art Relied Upon: Ostler (Patent 6,954,270) and Sanpei (EP Publication # 1 895 602).

  • Core Argument: Petitioner argued that, to the extent Ostler is found not to anticipate, it would have been obvious to a person of ordinary skill in the art (POSITA) to modify Ostler’s LED array using the teachings of Sanpei to arrive at the claimed invention.

    • Prior Art Mapping: Ostler teaches an LED array with GaN chips mounted directly on a metal heat sink and connected in a "chip to chip" fashion. Sanpei teaches a dedicated metal substrate with a highly reflective surface (e.g., silver plating) specifically designed to serve as an interface between LED chips and a heat sink to improve light output and thermal dissipation.
    • Motivation to Combine: A POSITA would combine these references as they are from the same field and address the identical problem of creating thermally and optically efficient LED arrays. Petitioner argued a POSITA would have been motivated to use Sanpei's specialized substrate and reflective layer as an interface in Ostler’s array to further Ostler's stated goals. This would have been a routine modification, combining known elements to achieve the predictable result of improved reflectivity and heat dissipation.
    • Expectation of Success: A POSITA would have reasonably expected success in combining the references. The modification involves applying Sanpei’s substrate—a known component for improving LED performance—to Ostler’s array using well-understood mounting techniques disclosed in both references, leading to predictable improvements.

  • Additional Grounds: Petitioner asserted an additional anticipation ground based on Ostler alone. Petitioner also presented obviousness challenges for claim 5 over Sanpei and Ostler, claim 4 over Baek and Sanpei, and claim 5 over Baek and Ostler, relying on similar motivations to combine references to optimize specific features like chip spacing and reflectivity.

4. Key Claim Construction Positions

  • "connecting the LED chips in a chip to chip fashion": Petitioner contended the broadest reasonable interpretation of this term is "connecting the LED chips in a manner that forms a horizontal current path from one chip to another." This construction, supported by the patent’s prosecution history, explicitly excludes arrangements where current passes vertically from the LED chip into the mounting substrate. This distinction was critical for the patentee to overcome prior art during examination and is central to Petitioner's argument that the prior art meets this limitation.

5. Key Technical Contentions (Beyond Claim Construction)

  • GaN LED Technology Context: Petitioner’s core technical contention was that the ’988 patent’s alleged invention was merely a routine and obvious consequence of the widespread adoption of Gallium Nitride (GaN) LED chips, which had dominated the industry for over a decade before the patent's filing. These modern chips inherently feature an insulating sapphire substrate and have both electrical contacts on their top surface. This design naturally enables direct mounting onto a metal substrate for superior heat sinking while allowing for horizontal, chip-to-chip wiring, rendering the ’988 patent’s claims obvious.

6. Relief Requested

  • Petitioner requests institution of an inter partes review and cancellation of claims 1-9 of the ’988 patent as unpatentable.