Light Emitting Diode Package
Patent No. US11978837 (titled "Light Emitting Diode Package") was filed by Seoul Semiconductor Co Ltd on Apr 20, 2022.
What is this patent about?
’837 is related to the field of light emitting diode (LED) packaging, specifically addressing side-view LED packages used in applications like backlight units for displays. These packages require efficient light extraction and reliable coupling to external substrates. Traditional side-view LED packages often face challenges in achieving tight coupling due to the thickness of solder connections and potential light leakage from the sides of the package.
The underlying idea behind ’837 is to improve the light extraction and substrate coupling of side-view LED packages by incorporating a reflective layer on the side of the LED die and using grooves in the housing that are filled with solder to improve mechanical coupling. Additionally, a surface barrier is introduced to protect the LED and wavelength converters from moisture and dust, enhancing reliability.
The claims of ’837 focus on a light emitting module unit comprising a circuit board, light emitters, electrodes, a first pad and a second pad, a surface barrier, and an encapsulation. Critically, the second pad acts as a common electrode for at least two light emitters. Each light emitter includes a light source with Group III-V semiconductors and a reflective layer on its surface. The reflective layer is a multilayer structure including at least one of Ag, Al, Ni, Ti, a distributed Bragg reflector, or an omnidirectional reflector.
In practice, the reflective layer redirects light emitted from the sides of the LED die towards the light exit surface, increasing light extraction efficiency and preventing light leakage. The grooves in the housing, positioned beneath the solder pads, allow for a more robust mechanical connection to the external substrate. The solder fills these grooves, increasing the contact area and improving the overall stability and thermal dissipation of the package.
This design differentiates itself from prior approaches by combining improved light management with enhanced mechanical coupling and environmental protection. The multilayer reflective layer provides both high reflectivity and thermal conductivity, addressing both light extraction and heat dissipation concerns. The surface barrier, in conjunction with the encapsulation, creates a dual-layer protection against moisture and dust, significantly improving the long-term reliability of the LED package, especially in demanding environments.
How does this patent fit in bigger picture?
Technical landscape at the time
In the late 2010s when ’837 was filed, light emitting diode (LED) packages were at a time when side-view packages were commonly used as light sources for backlight units in display apparatuses. At this time, tight coupling between the LED package and an exterior substrate was a non-trivial engineering constraint, as conventional packages often relied on solder connections that introduced thickness and made close integration challenging.
Novelty and Inventive Step
The examiner approved the application because the prior art of record did not anticipate or render obvious the claimed invention. Specifically, the prior art failed to teach a combination of elements including a circuit board, light emitters, electrodes on a first surface of the light emitters, a first and second pad electrically connected to the electrodes and light emitters, a surface barrier on a second surface of the light emitters, and an encapsulation disposed on a third surface of the light emitters, where the second pad is electrically connected to at least two light emitters to act as a common electrode. The examiner also noted that the prior art did not teach a reflective layer disposed between the light source and the encapsulation, where the reflective layer includes a material having thermal conductivity and reflectivity, and where the second pad is electrically connected to at least two light emitters to act as a common electrode.
Claims
This patent contains 18 claims, with claims 1, 8, and 15 being independent. The independent claims are directed to a light emitting module unit comprising a circuit board, light emitters, electrodes, pads, a reflective layer, and an encapsulation. The dependent claims generally add further details or limitations to the elements and configurations described in the independent claims.
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Date
Description
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US11978837
- Application Number
- US17724864
- Filing Date
- Apr 20, 2022
- Status
- Granted
- Expiry Date
- May 10, 2038
- External Links
- Slate, USPTO, Google Patents