PTAB

IPR2021-01479

Seoul Semiconductor Co Ltd v. LED Wafer Solutions LLC

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Petition
petition

1. Case Identification

2. Patent Overview

  • Title: Light Emitting Diode Package and Method of Manufacture
  • Brief Description: The ’405 patent describes a light emitting diode (LED) package with a stacked, multi-layer structure. The core technology involves a semiconductor LED with positively-doped, negatively-doped, and intrinsic regions on a sapphire substrate, arranged with various permissive and passivation layers intended to improve the device's mechanical, thermal, and optical characteristics.

3. Grounds for Unpatentability

Ground 1: Obviousness over Sugizaki, Schubert, and Nakamura - Claims 1-3, 8-14, and 16 are obvious over Sugizaki in view of Schubert or Nakamura.

  • Prior Art Relied Upon: Sugizaki (Application # 2010/0148198), Schubert (Light Emitting Diodes (2d ed. 2006)), and Nakamura (Patent 5,777,350).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner argued that Sugizaki, which discloses a flip-chip LED design, teaches nearly every structural limitation of independent claim 1. This includes a semiconductor LED with positively- and negatively-doped regions separated by a light-emitting layer, a recess to expose the n-doped surface, metallization for electrical contacts, a sapphire layer, an optically permissive phosphor layer, a cover substrate, and a passivation layer with contact holes. The only element Petitioner contended is not explicitly disclosed in Sugizaki is that the light-emitting layer is "intrinsic" (i.e., undoped).
    • Motivation to Combine: A Person of Ordinary Skill in the Art (POSITA) would have been motivated to modify Sugizaki’s light-emitting layer to be intrinsic based on the teachings of Schubert or Nakamura. Both secondary references explain that using an undoped, or intrinsic, active layer is a conventional technique that provides significant benefits, such as improving radiative efficiency, enhancing crystallinity, and lowering the forward voltage of the LED.
    • Expectation of Success: Because using an intrinsic active layer was a well-known and advantageous design choice for improving LED performance, a POSITA would have had a high expectation of success in implementing this feature into the device disclosed by Sugizaki.

Ground 2: Obviousness over Sugizaki Combination and Hashimoto - Claim 4 is obvious over the combination of Ground 1 and Hashimoto.

  • Prior Art Relied Upon: Sugizaki, Schubert/Nakamura, and Hashimoto (Application # 2004/0012958).
  • Core Argument for this Ground:
    • Prior Art Mapping: This ground builds on the primary combination to address dependent claim 4, which further requires the passivation layer to have a "shaped edge" configured to reflect light. Petitioner argued that while Sugizaki discloses a passivation layer with a vertical edge, Hashimoto teaches shaping the periphery of LED layers with an incline.
    • Motivation to Combine: A POSITA would incorporate Hashimoto’s shaped edge into the Sugizaki device for the explicit purpose of improving performance. Hashimoto teaches that a vertical surface can "hinder light from being released to the outside," and that forming an inclined surface improves light extraction from the chip.

Ground 3: Obviousness over Sugizaki Combination and Lee - Claim 6 is obvious over the combination of Ground 1 and Lee.

  • Prior Art Relied Upon: Sugizaki, Schubert/Nakamura, and Lee (Application # 2008/0023721).

  • Core Argument for this Ground:

    • Prior Art Mapping: This ground addresses dependent claim 6, which adds a "mechanical offsetting member" that provides spacing between the optically permissive layer and the cover substrate. Lee discloses a multi-layer resin package where a harder second molding resin is placed over a softer, phosphor-containing first resin, providing a structurally robust layer between the phosphor and the final lens.
    • Motivation to Combine: Lee explicitly teaches that this harder second layer prevents deformation of the softer underlying resin, alleviates thermal stress, and improves the overall reliability of the LED package. A POSITA would combine Lee’s teaching with the Sugizaki device to gain these known benefits of improved durability and performance.

  • Additional Grounds: Petitioner asserted an alternative obviousness challenge (Ground 4) for claims 1-4 and 8-16, also relying on the combination of Sugizaki, Schubert/Nakamura, and Lee. This ground proposed that Lee's harder resin layer could alternatively satisfy the "optically permissive cover substrate" limitation of claim 1.

4. Key Claim Construction Positions

  • intrinsic: Petitioner proposed this term means "undoped or not-doped." This construction was based on the patent’s explicit contrast between "doped and intrinsic regions" and supported by technical dictionary definitions. The construction is critical to the core obviousness argument, as it defines the precise feature allegedly supplied by Schubert and Nakamura to the Sugizaki reference.
  • metallization: Petitioner argued this term encompasses "one or more metal layers applied to a device." This construction relies on figures in the ’405 patent that show two separate metal areas for the p-side and n-side contacts, countering any potential interpretation that the claim requires a single, continuous metal layer, which would render the device non-functional.

5. Relief Requested

  • Petitioner requests institution of an inter partes review and cancellation of claims 1-4, 6, 8-14, and 16 of Patent 8,952,405 as unpatentable.