DCT

2:26-cv-00724

Seoul Semiconductor Co Ltd v. Partron Co Ltd

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I. Executive Summary and Procedural Information

  • Parties & Counsel:
  • Case Identification: 2:26-cv-00724, E.D. Tex., 08/21/2026
  • Venue Allegations: Plaintiffs allege venue is proper because Defendant is a foreign corporation subject to personal jurisdiction in the district. This jurisdiction is based on Defendant allegedly transacting business and committing acts of patent infringement in the district, including placing its products into the stream of commerce with the knowledge that they would be sold in Texas.
  • Core Dispute: Plaintiffs allege that Defendant's flash Light Emitting Diode (LED) modules, which are incorporated into various Samsung smartphones, infringe ten U.S. patents related to LED structure, packaging, and operation.
  • Technical Context: The technology at issue is light-emitting diodes (LEDs), semiconductor devices that are foundational to modern electronics, particularly in mobile phone camera flash units and display backlights, valued for their efficiency, longevity, and small size.
  • Key Procedural History: The complaint states that on August 13, 2026, just eight days before filing suit, Plaintiffs notified Defendant that its flash LED modules infringed the ten patents-in-suit. This pre-suit notice is presented as the basis for Plaintiffs' willful infringement allegations.

Case Timeline

Date Event
2008-08-04 Priority Date for U.S. Patent No. 7,667,225
2010-01-05 Priority Date for U.S. Patent No. 9,716,210
2010-02-23 U.S. Patent No. 7,667,225 Issues
2010-09-24 Priority Date for U.S. Patent No. 9,070,851
2010-09-24 Priority Date for U.S. Patent No. 10,892,386
2011-02-09 Priority Date for U.S. Patent No. 9,112,120
2013-05-01 Priority Date for U.S. Patent No. 9,520,543
2015-06-30 U.S. Patent No. 9,070,851 Issues
2015-08-18 U.S. Patent No. 9,112,120 Issues
2016-12-13 U.S. Patent No. 9,520,543 Issues
2017-07-25 U.S. Patent No. 9,716,210 Issues
2017-12-08 Priority Date for U.S. Patent No. 12,546,458
2018-07-12 Priority Date for U.S. Patent No. 11,876,151
2018-09-14 Priority Date for U.S. Patent No. 12,298,552
2019-01-31 Priority Date for U.S. Patent No. 12,302,679
2021-01-12 U.S. Patent No. 10,892,386 Issues
2024-01-16 U.S. Patent No. 11,876,151 Issues
2025-05-13 U.S. Patent No. 12,298,552 Issues
2025-05-13 U.S. Patent No. 12,302,679 Issues
2026-02-10 U.S. Patent No. 12,546,458 Issues
2026-08-13 Plaintiffs Notify Defendant of Infringement
2026-08-21 Complaint Filed

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

U.S. Patent No. 12,298,552 - "Backlight unit and display apparatus having the same"

  • Patent Identification: U.S. Patent No. 12,298,552, "Backlight unit and display apparatus having the same," issued May 13, 2025.
  • The Invention Explained:
    • Problem Addressed: The patent describes the challenge of designing thin backlight units for displays, where conventional direct-lighting and edge-lighting configurations face limitations in reducing thickness while maintaining uniform brightness ("'552 Patent, col. 1:19-54").
    • The Patented Solution: The invention proposes a light source unit with a specific geometry to control the emission of light. It comprises a light emitter on a substrate with pad electrodes, where the arrangement and spacing of the electrodes are designed to manage the light profile and achieve a slim form factor ("'552 Patent, abstract; '552 Patent, col. 10:1-13"). This configuration aims to guide light laterally rather than directly upwards, improving uniformity.
    • Technical Importance: This technology aims to enable the production of thinner, more uniform, and potentially more power-efficient backlight units, a critical factor in the competitive market for displays in devices like mobile phones and televisions ("'552 Patent, col. 1:44-54").
  • Key Claims at a Glance:
    • The complaint asserts exemplary independent claim 15 ("Compl. ¶35").
    • The essential elements of independent claim 15 are:
      • A light emitting device comprising: a substrate; a light emitter disposed on the substrate and configured to emit light;
      • a reflector disposed on the substrate and configured to reflect light emitted from the light emitter;
      • a light guide disposed on the substrate and configured to diffuse the light from the light emitter;
      • wherein the light emitter includes a first contact electrode and a second contact electrode;
      • wherein the substrate includes a first pad electrode electrically connected to the first contact electrode and a second pad electrode electrically connected to the second contact electrode;
      • wherein the light emitter has a first length in a first direction in which the first and second contact electrodes are arranged and a second length in a second direction substantially perpendicular to the first direction, wherein the first length of the light emitter is greater than the second length;
      • wherein a gap between the first pad electrode and the second pad electrode is different from the first length or the second length; and
      • wherein the gap is greater than about 50 micrometers (µm).

U.S. Patent No. 11,876,151 - "Light emitting device, light emitting diode package, backlight unit, and liquid crystal display"

  • Patent Identification: U.S. Patent No. 11,876,151, "Light emitting device, light emitting diode package, backlight unit, and liquid crystal display," issued January 16, 2024.
  • The Invention Explained:
    • Problem Addressed: The patent identifies the "spot phenomenon" in direct-lighting backlights, where individual LEDs create visible bright spots, harming light uniformity and making it difficult to create thin displays ("'151 Patent, col. 1:57 - col. 2:11"). It also notes that even with measures to spread light, achieving a clear blackout for local dimming can be difficult due to light leakage from adjacent LEDs ("'151 Patent, col. 2:19-24").
    • The Patented Solution: The invention discloses a light emitting diode package that includes a "dam" structure on the circuit board, surrounding the light emitter ("'151 Patent, abstract"). The dam is spaced apart from the emitter and its height is configured relative to the light emitter's peak beam angle to restrict upward light and promote lateral spreading ("'151 Patent, col. 7:27-38; '151 Patent, FIG. 13"). This structure is intended to improve brightness uniformity and enable clearer local dimming by optically isolating individual emitters.
    • Technical Importance: By controlling the light path at the source, this technology facilitates the design of thinner direct-lit backlights with improved contrast and suitability for local dimming, which enhances both image quality and power efficiency ("'151 Patent, col. 2:42-53").
  • Key Claims at a Glance:
    • The complaint asserts exemplary independent claim 9 ("Compl. ¶45").
    • The essential elements of independent claim 9 are:
      • A display apparatus, comprising: a circuit board; and at least one light emitter disposed on the circuit board;
      • the light emitter comprising: a light emitting structure disposed on the circuit board; a first electrode pad and a second electrode pad; a light transmitting layer covering at least one surface of the light emitter;
      • and a dam disposed on the circuit board and surrounding a portion of the light emitter and a portion of the light transmitting layer;
      • wherein the dam has a height to form an angle from an optical axis of a light emitting surface to a top surface of the dam to be greater than a peak beam angle of the light emitter.

U.S. Patent No. 12,546,458 - "Backlight unit"

  • Patent Identification: U.S. Patent No. 12,546,458, "Backlight unit," issued February 10, 2026 ("Compl. ¶18").
  • Technology Synopsis: The patent describes a backlight unit with a light-emitting diode chip and multiple reflection members stacked on top of it. The reflection members have progressively smaller areas, which allows for precise control of the ratio of light emitted upwards versus laterally, thereby improving light uniformity ("'458 Patent, abstract; '458 Patent, col. 2:1-10").
  • Asserted Claims: Exemplary claim 9 ("Compl. ¶56").
  • Accused Features: The complaint alleges that the flash LED modules in Samsung phones, such as the Galaxy S26, contain a sealing layer, a light guide, and a layered LED chip structure that infringes this patent ("Compl. ¶¶58-62").

U.S. Patent No. 12,302,679 - "Light emitting diode"

  • Patent Identification: U.S. Patent No. 12,302,679, "Light emitting diode," issued May 13, 2025 ("Compl. ¶19").
  • Technology Synopsis: This patent details a light-emitting diode with a specific internal structure designed for high efficiency and reliability. The invention involves a mesa structure with carefully defined layers, including semiconductor layers, a transparent conductive oxide layer, a metal reflection layer, and a dielectric layer, with specific thickness ranges and compositions (e.g., Mg-doped layers) to optimize light generation and extraction ("'679 Patent, abstract; '679 Patent, col. 2:30-49").
  • Asserted Claims: Exemplary claim 1 ("Compl. ¶67").
  • Accused Features: The infringement allegations focus on the internal structure of the LED chip within the accused modules, identified through SEM imagery. These include the layered semiconductor structure, the use of a blue LED chip, Mg doping, and specific metal and dielectric reflection layers ("Compl. ¶¶69-72").

U.S. Patent No. 9,112,120 - "White light source and white light source system including the same"

  • Patent Identification: U.S. Patent No. 9,112,120, "White light source and white light source system including the same," issued August 18, 2015 ("Compl. ¶20").
  • Technology Synopsis: The invention concerns a white light source designed to have a light emission spectrum that closely mimics that of natural light. It achieves this by satisfying a specific relational equation that compares its spectral output against that of black-body radiation at the same color temperature, aiming to minimize adverse effects on human circadian rhythms ("'120 Patent, abstract; '120 Patent, col. 2:45-56").
  • Asserted Claims: Exemplary claim 1 ("Compl. ¶77").
  • Accused Features: The complaint alleges that the measured light output from the flash LED module in the Samsung Galaxy S26 Ultra satisfies the specific relational equation required by the patent's claims ("Compl. ¶80").

U.S. Patent No. 9,520,543 - "Light-emitting diode module having light-emitting diode joined through solder paste and light-emitting diode"

  • Patent Identification: U.S. Patent No. 9,520,543, "Light-emitting diode module having light-emitting diode joined through solder paste and light-emitting diode," issued December 13, 2016 ("Compl. ¶21").
  • Technology Synopsis: This patent describes an LED module where the LED is bonded to a circuit board via solder paste. The invention focuses on the electrode structure of the LED chip, which includes a reflective electrode and an anti-diffusion reinforcing layer to prevent elements from the solder paste (like Sn) from diffusing into the diode and causing failure ("'543 Patent, abstract; '543 Patent, col. 2:4-10").
  • Asserted Claims: Exemplary claim 1 ("Compl. ¶85").
  • Accused Features: The complaint accuses the LED package in the Samsung Galaxy S26 of having the claimed structure, including a reflective electrode and an anti-diffusion reinforcing layer, as shown in cross-sectional SEM images ("Compl. ¶¶87-89").

U.S. Patent No. 10,892,386 - "Wafer-level light emitting diode package and method of fabricating the same"

  • Patent Identification: U.S. Patent No. 10,892,386, "Wafer-level light emitting diode package and method of fabricating the same," issued January 12, 2021 ("Compl. ¶22").
  • Technology Synopsis: The patent discloses a wafer-level LED package designed for direct mounting on a circuit board without bonding wires. The structure involves a semiconductor stack with specific contact holes and bumps, and importantly, a protective insulation layer that covers the entire sidewall of the semiconductor stack to protect it from the external environment ("'386 Patent, abstract; '386 Patent, claim 17").
  • Asserted Claims: Exemplary claim 17 ("Compl. ¶94").
  • Accused Features: The accused LED packages are alleged to have the claimed wire-bond-free structure, with SEM and optical images purportedly showing the semiconductor stack and a protective insulation layer covering its entire sidewall ("Compl. ¶¶96-99").

U.S. Patent No. 9,070,851 - "Wafer-level light emitting diode package and method of fabricating the same"

  • Patent Identification: U.S. Patent No. 9,070,851, "Wafer-level light emitting diode package and method of fabricating the same," issued June 30, 2015 ("Compl. ¶23").
  • Technology Synopsis: This patent is related to the '386 patent and also describes a wafer-level LED package. A key feature is the method of forming electrical connections through contact holes that penetrate through the p-type and active layers to expose the underlying n-type layer, allowing for both electrical contacts to be on the same side of the chip ("'851 Patent, abstract; '851 Patent, col. 3:9-24").
  • Asserted Claims: Exemplary claim 1 ("Compl. ¶104").
  • Accused Features: The complaint alleges the accused LED chips use the claimed structure, with SEM images showing contact holes penetrating the p-type and active layers to connect with the n-type layer, and bumps on the bottom of the chip for connection ("Compl. ¶¶106-109").

U.S. Patent No. 9,716,210 - "Light emitting diode and method of fabricating the same"

  • Patent Identification: U.S. Patent No. 9,716,210, "Light emitting diode and method of fabricating the same," issued July 25, 2017 ("Compl. ¶24").
  • Technology Synopsis: This invention relates to an LED structure with features designed to improve crystal quality and light efficiency. It describes a multi-quantum well active layer near which a superlattice layer is disposed, with a spacer layer having a specific bandgap relationship to the quantum well layers, which helps manage carrier confinement and improve performance ("'210 Patent, abstract; '210 Patent, claim 1").
  • Asserted Claims: Exemplary claim 1 ("Compl. ¶114").
  • Accused Features: The complaint alleges, based on SEM imagery, that the accused LED chip has a multi-quantum well structure and, upon information and belief, includes a superlattice layer and a spacer layer with the specific bandgap properties claimed ("Compl. ¶¶117-118").

U.S. Patent No. 7,667,225 - "Light emitting device"

  • Patent Identification: U.S. Patent No. 7,667,225, "Light emitting device," issued February 23, 2010 ("Compl. ¶25").
  • Technology Synopsis: This patent describes a light-emitting device with a multi-quantum well structure containing at least one "carrier trap portion." This carrier trap is designed to have a band-gap energy that gradually decreases from its periphery to its center, which serves to trap charge carriers and enhance radiative recombination, thereby improving quantum efficiency and mitigating issues caused by crystal defects ("'225 Patent, abstract"). An inter partes review certificate confirmed the patentability of the asserted claims ("'225 Patent, IPR Certificate").
  • Asserted Claims: Exemplary claim 1 ("Compl. ¶123").
  • Accused Features: Based on SEM images, the complaint alleges on information and belief that the multi-quantum well structure in the accused device contains at least one carrier trap portion with the claimed decreasing band-gap energy profile ("Compl. ¶¶126-127").

III. The Accused Instrumentality

Product Identification

  • The accused instrumentalities are "flash LED modules" designed, manufactured, and supplied by Defendant Partron ("Compl. ¶10").

Functionality and Market Context

  • These LED modules are incorporated as camera flash components into various Samsung mobile phones, including the Samsung Galaxy S26, S26 Ultra, S25, and Z Flip6 models ("Compl. ¶10"). The complaint alleges these modules are critical components for the camera functionality of these widely distributed smartphones ("Compl. ¶11"). The complaint provides product marketing imagery from Partron's website, which explicitly identifies "Flash LED" as a component for mobile devices ("Compl., p. 9"). The phones incorporating these modules are allegedly sold in the district through major retail channels, including Samsung's own website and Walmart ("Compl. ¶12").

IV. Analysis of Infringement Allegations

U.S. Patent No. 12,298,552 Infringement Allegations

Claim Element (from Independent Claim 15) Alleged Infringing Functionality Complaint Citation Patent Citation
a light emitter ... wherein the light emitter has a first length in a first direction in which the first and second contact electrodes are arranged and a second length in a second direction substantially perpendicular to the first direction, wherein the first length of the light emitter is greater than the second length The complaint presents an image of the LED package from a Samsung Galaxy S26 Ultra, alleging that the package is longer in the horizontal direction where the contact electrodes are arranged and shorter in the perpendicular vertical direction. ¶38 col. 6:42-50
the substrate includes a first pad electrode and a second pad electrode ... wherein a gap between the first pad electrode and the second pad electrode is different from the first length or the second length, and wherein the gap is greater than about 50 micrometers (µm) A close-up image of the substrate after removal of the LED package allegedly shows a pair of pad electrodes. The complaint alleges the gap between these pads is greater than 50 micrometers and smaller than the length of the light emitter. ¶¶39-40 col. 5:48-67
  • Identified Points of Contention:
    • Scope Questions: A central question will be whether the accused component, described as an "LED package" in the complaint ("Compl. ¶38"), meets all the structural limitations of the claimed "light emitting device," which includes a substrate, emitter, reflector, and light guide.
    • Technical Questions: The infringement analysis will turn on factual verification of the dimensional claims. A key evidentiary question for the court will be whether the measured gap between the pad electrodes on the accused substrate is, in fact, greater than 50 micrometers as claimed and alleged ("Compl. ¶40").

U.S. Patent No. 11,876,151 Infringement Allegations

Claim Element (from Independent Claim 9) Alleged Infringing Functionality Complaint Citation Patent Citation
a dam disposed on the circuit board and surrounding a portion of the light emitter and a portion of the light transmitting layer An image of the LED package allegedly shows a "white dam" that surrounds the yellow light transmitting layer. A cross-sectional SEM image is also presented to show the dam surrounding a portion of the light emitter and the light transmitting layer. ¶51 col. 7:27-31
wherein the dam has a height to form an angle (θ) from an optical axis of a light emitting surface to a top surface of the dam to be greater than a peak beam angle of the light emitter The complaint alleges that the height of the dam in the accused device forms an angle from the optical axis of the light emitter's surface that is greater than the peak beam angle of the light emitter. This allegation is supported by the provided cross-sectional image. ¶51 col. 7:31-38
  • Identified Points of Contention:
    • Scope Questions: A primary issue for claim construction will be the definition of a "dam." The court will need to determine if the "white dam" identified in the complaint's images ("Compl. ¶51") constitutes a "dam" within the meaning of the patent.
    • Technical Questions: The infringement analysis will require evidence confirming the functional properties of the accused "dam." A key question is whether the structure identified as a dam actually performs the claimed optical function of shaping the light emission to have an angle greater than the peak beam angle, or if it is a structurally similar but functionally distinct feature.

V. Key Claim Terms for Construction

  • The Term: "light emitter" ("'552 Patent, claim 15)
  • Context and Importance: The claim requires the "light emitter" to have a specific dimensional relationship (first length > second length). The complaint maps this to the dimensions of the entire "LED package" ("Compl. ¶38"). Practitioners may focus on this term because its construction will determine what physical object's dimensions are measured for infringement analysis-the entire package or just the semiconductor die within it.
  • Intrinsic Evidence for Interpretation:
    • Evidence for a Broader Interpretation: The patent does not appear to provide an explicit definition that would broaden the term beyond the semiconductor chip itself. Parties arguing for a broader scope might suggest that in the context of the claims, the "emitter" refers to the entire packaged component that emits light.
    • Evidence for a Narrower Interpretation: The detailed description consistently refers to the "light emitting diode chip" or "light emitting structure" when discussing the core semiconductor component ("'151 Patent, col. 7:20-22"). This may support an argument that "light emitter" refers specifically to the semiconductor die, not the entire package assembly.
  • The Term: "dam" ("'151 Patent, claim 9)
  • Context and Importance: The presence and specific geometric/functional properties of the "dam" are central to claim 9. The complaint identifies a "white dam" in the accused product ("Compl. ¶51"). The construction of this term will be critical, as the defendant may argue the identified structure is merely a housing or encapsulant, not a "dam" that performs the claimed optical function of controlling the beam angle.
  • Intrinsic Evidence for Interpretation:
    • Evidence for a Broader Interpretation: The patent states the dam is "disposed on the circuit board and surrounding a lateral side of the light emitting diode chip" ("'151 Patent, col. 7:27-29"), which could be read to encompass any wall-like structure in that location.
    • Evidence for a Narrower Interpretation: The patent explicitly links the dam's height to an optical function: forming an angle "greater than a peak beam angle of the light emitting diode chip" to control light spread ("'151 Patent, col. 7:31-38"). This functional language may support a narrower construction requiring proof that the accused structure performs this specific light-shaping function, rather than just being a surrounding wall.

VI. Other Allegations

  • Indirect Infringement: Plaintiffs allege that Partron actively induces infringement by providing customers like Samsung with "data sheets, specifications, technical guides, application information, and other technical and commercial support" that instruct and encourage the incorporation of the accused flash LED modules into mobile phones ("Compl. ¶28"). The complaint also references Partron's website as providing such technical guidance ("Compl. ¶28").
  • Willful Infringement: The willfulness allegation is based on alleged pre-suit knowledge. The complaint states that Plaintiffs sent a notice letter to Defendant on August 13, 2026, identifying the asserted patents and the infringing products ("Compl. ¶26"). The complaint further alleges that Defendant provided no response and took no corrective action, thereby engaging in ongoing, willful infringement ("Compl. ¶27").

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

  1. A central issue will be one of structural and functional correspondence: Do the physical structures within Partron's LED modules, as documented through extensive photographic and SEM evidence in the complaint, actually meet the specific dimensional and functional limitations of the claims? This will involve resolving whether the accused "white dam" ("'151 Patent") performs the claimed optical function and whether the measured light output ("'120 Patent") satisfies the claimed mathematical equation.
  2. A key legal question will be inducement and willfulness: Did Partron's alleged pre-suit knowledge from the August 13, 2026 notice letter, combined with its continued supply and technical support to Samsung, constitute the specific intent required for induced infringement? Furthermore, does this conduct, particularly the lack of response to the notice, rise to the level of egregious behavior that would justify a finding of willfulness and enhanced damages?
  3. The case will also turn on claim construction: The viability of several infringement theories will depend on how the court construes key terms. A core definitional question will be whether "light emitter" ("'552 patent") refers to the semiconductor die or the entire LED package, and whether the term "dam" ("'151 patent") requires proof of a specific optical function or can be read more broadly as a structural feature.