PTAB

IPR2018-01484

Everlight Electronics Co., Ltd. v. Bridgelux, Inc.

Log In

1. Case Identification

2. Patent Overview

  • Title: Efficient LED Array
  • Brief Description: The ’051 patent discloses a method for forming an LED apparatus by mounting a plurality of LED chips directly onto the reflective surface of a metal substrate. The method includes spacing the LED chips apart to allow for thermal dissipation and to permit light to reflect from the surface between the chips.

3. Grounds for Unpatentability

Ground 1: Anticipation by Sanpei - Claims 1-7 are anticipated by Sanpei under 35 U.S.C. §102.

  • Prior Art Relied Upon: Sanpei (EP Patent Publication No. 1 895 602).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner asserted that Sanpei taught every limitation of claims 1-7. Sanpei disclosed an LED array with nitride-based (GaN) LED chips mounted on a metal baseboard (e.g., aluminum or copper) configured with a highly reflective silver-plated surface. Sanpei’s chips, having both contacts on the upper surface, were mounted to create separate horizontal electrical paths and vertical thermal paths, and were spaced at intervals to allow light to reflect off the silver plating. Petitioner contended this spacing was inherently greater than 0.5 mm and the silver plating inherently had a reflectivity greater than 70%, thus meeting all limitations of the independent and dependent claims.

Ground 2: Obviousness over Ostler and Sanpei - Claims 1-7 are obvious over Ostler in view of Sanpei under 35 U.S.C. §103.

  • Prior Art Relied Upon: Ostler (Patent 6,954,270), Sanpei (EP Patent Publication No. 1 895 602).
  • Core Argument for this Ground:
    • Prior Art Mapping: This ground was presented as an alternative to an anticipation argument based on Ostler. Petitioner argued that Ostler taught mounting an array of LED chips directly onto a metal heat sink and spacing them by at least one millimeter. To the extent Ostler was found not to disclose a "metal substrate to have a reflective surface," Petitioner asserted a person of ordinary skill in the art (POSITA) would look to Sanpei, which explicitly taught a metal substrate with a reflective layer (e.g., silver plating) for the express purpose of improving heat dissipation and light reflection in an LED array.
    • Motivation to Combine: A POSITA would combine the references to further the shared goal of creating an optically and thermally efficient LED array. Petitioner argued it would have been obvious to use Sanpei's purpose-built reflective metal substrate as an interface between Ostler's LED chips and heat sink to improve upon Ostler's design.
    • Expectation of Success: A POSITA would have reasonably expected success, as both references disclosed techniques for mounting LEDs to metal surfaces. The combination involved applying known elements (Sanpei's substrate) using known methods to achieve the predictable results of improved reflectivity and heat dissipation.

Ground 3: Obviousness over Baek and Ostler - Claims 1-7 are obvious over Baek in view of Ostler under §103.

  • Prior Art Relied Upon: Baek (Application # 2007/0075325), Ostler (Patent 6,954,270).

  • Core Argument for this Ground:

    • Prior Art Mapping: Petitioner contended that Baek disclosed nearly all limitations, including an array of GaN LED chips mounted on a reflective metal substrate (e.g., copper with silver plating) to provide separate thermal and electrical paths. To the extent Baek was found not to explicitly teach the claimed chip spacing of "at least 0.5 millimeters," Petitioner argued it would have been obvious to incorporate the spacing taught by Ostler. Ostler expressly taught spacing LED chips in an array at one millimeter or more to improve thermal efficiency.
    • Motivation to Combine: Both Baek and Ostler addressed the same problem of improving heat dissipation and reflectivity in LED arrays. A POSITA would have recognized Ostler's teaching on chip spacing as a known design parameter directly applicable to optimizing Baek's LED array. The motivation was to improve thermal performance and light output, a goal shared by both references.
    • Expectation of Success: The combination would have been a simple and predictable modification. A POSITA would have understood that adjusting the spacing of the LED chips in Baek's design to the specific distance taught by Ostler would predictably improve thermal distribution and reflectivity, a routine design trade-off.

  • Additional Grounds: Petitioner also asserted that claims 1-7 were anticipated by Ostler. Further, Petitioner presented obviousness challenges arguing that if Sanpei was found not to disclose the 0.5 mm spacing, it would be obvious to combine Sanpei with Ostler to arrive at the claimed invention. Finally, Petitioner argued claim 4 was obvious over the three-way combination of Baek, Ostler, and Sanpei to ensure the 70% reflectivity limitation was met.

4. Key Technical Contentions (Beyond Claim Construction)

  • Evolution of LED Technology: A central technical argument was that the claimed invention was merely a routine and obvious application of known principles following the development of Gallium Nitride (GaN) LEDs in the 1990s. Petitioner explained that older LED types required top and bottom electrical contacts, necessitating an insulating ceramic layer when mounted on a metal heat sink. In contrast, GaN LEDs—which dominated the industry by the patent's 2008 priority date—were grown on an insulating sapphire substrate and had both electrical contacts on the top surface. This fundamental design change, well-known in the art, eliminated the need for a separate ceramic insulator and made the direct mounting of LEDs onto a reflective metal substrate for improved thermal and optical performance an obvious design choice.

5. Relief Requested

  • Petitioner requested institution of an inter partes review and cancellation of claims 1-7 of the ’051 patent as unpatentable.