Abstract: Aspects of the present disclosure relate to a light-emitting system comprising a plurality of LEDs having relatively small nearest-neighbor distances (e.g., a close-packed array of LEDs). In some cases, one or more LEDs of the plurality of LEDs comprise a via between a semiconductor layer (e.g., an n-type semiconductor layer forming part of a p-n junction) and a heat dissipation substrate. The presence of the vias may advantageously reduce or eliminate current crowding and may allow the LEDs to be operated at a high current density (e.g., at least 1A/mm2). In some cases, one or more LEDs of the plurality of LEDs comprise a first contact pad (e.g., an n-side contact pad) and a second contact pad (e.g., a p-side contact pad) positioned in any location, which may allow the LEDs to be configured in series or in parallel, or to be individually addressable. The first and second contact pads of the LEDs may be electrically connected to other elements of the light-emitting system (e.g.

Abstract: Aspects of the present disclosure relate to a light-emitting system comprising a plurality of LEDs having relatively small nearest-neighbor distances (e.g., a close-packed array of LEDs). In some cases, one or more LEDs of the plurality of LEDs comprise a via between a semiconductor layer (e.g., an n-type semiconductor layer forming part of a p-n junction) and a heat dissipation substrate. The presence of the vias may advantageously reduce or eliminate current crowding and may allow the LEDs to be operated at a high current density (e.g., at least 1 A/mm2). In some cases, one or more LEDs of the plurality of LEDs comprise a first contact pad (e.g., an n-side contact pad) and a second contact pad (e.g., a p-side contact pad) positioned in any location, which may allow the LEDs to be configured in series or in parallel, or to be individually addressable. The first and second contact pads of the LEDs may be electrically connected to other elements of the light-emitting system (e.g.

Abstract: Aspects of the present disclosure relate to systems for emitting light (e.g., substantially white light) with tunable circadian effects and substantially consistent color characteristics, and methods of making and/or operating the same. Certain embodiments described herein are systems comprising a plurality of light-emitting regions configured to emit light having certain circadian effects (e.g., melanopic ratio) and certain color characteristics (e.g., corrected color temperature (CCT), color rendering index (CRI)). According to some embodiments, the difference between the circadian effects of the light-emitting regions may be relatively large, and the difference between the color characteristics of the light-emitting regions may be relatively small. Each light-emitting region may comprise one or more light-emitting diodes (LEDs), each of which may be associated with one or more wavelength-converting materials (e.g., phosphors).

Abstract: Devices and methods including an LED and reflective die attach material are described herein. The devices can include a reflective substrate (e.g., a substrate that includes a silver layer) to which one or more LED die are attached using the die attach material. The die attach material extends beyond the periphery of the LED die to cover an area of the substrate surface.

Abstract: An LED assembly includes two strings of surface mounted LED devices mounted to a central ceramic plug portion of a PCB substrate. One string has a CCT of 4000 degrees Kelvin. The other has a CCT of 1800 degrees Kelvin. For each LED device in one string there is a corresponding LED device in the other string. The LED devices of each pair are closely spaced with 0.2-0.6 mm between them. A Highly Reflective (HR) layer is disposed on the substrate between the LED devices. The HR layer has a thickness in a range of from 20 to 50 percent H, where H is the height of an LED die. A transparent silicone layer covers the LED devices. A resistor of a warm-dimming circuit is mounted over the ceramic portion of the substrate whereas an integrated circuit portion of the circuit is mounted over the PCB portion of the substrate.

Abstract: Methods and apparatus are provided to improve long-term reliability of LED packages using reflective opaque die attach (DA) material. In one novel aspect, a protected area surrounding edges of the LED is determined. The DA is applied to the determined protected area by a dispense process, a stamping process, or a screen printing process, such that the effect of temperature degradation is reduced. A heat distribution model is used to determine the protected area, which is between edges of the LED and a predefined isothermal line where the temperature is 1/e that of the temperature at edges of the LED. In another embodiment, the protected area is further based on a spreading ratio of the substrate size to the LED size. In another novel aspect, with multiple LEDs in the LED package, the spreading ratio is further based on pitch distances to the immediate adjacent LEDs and the substrate boundary.

Abstract: An LED assembly includes two strings of surface mounted LED devices mounted to a central ceramic plug portion of a PCB substrate. One string has a CCT of 4000 degrees Kelvin. The other has a CCT of 1800 degrees Kelvin. For each LED device in one string there is a corresponding LED device in the other string. The LED devices of each pair are closely spaced with 0.2-0.6 mm between them. A Highly Reflective (HR) layer is disposed on the substrate between the LED devices. The HR layer has a thickness in a range of from 20 to 50 percent H, where H is the height of an LED die. A transparent silicone layer covers the LED devices. A resistor of a warm-dimming circuit is mounted over the ceramic portion of the substrate whereas an integrated circuit portion of the circuit is mounted over the PCB portion of the substrate.

Abstract: Methods and apparatus are provided to improve long-term reliability of LED packages using reflective opaque die attach (DA) material. In one novel aspect, a protected area surrounding edges of the LED is determined. The DA is applied to the determined protected area by a dispense process, a stamping process, or a screen printing process, such that the effect of temperature degradation is reduced. A heat distribution model is used to determine the protected area, which is between edges of the LED and a predefined isothermal line where the temperature is 1/e that of the temperature at edges of the LED. In another embodiment, the protected area is further based on a spreading ratio of the substrate size to the LED size. In another novel aspect, with multiple LEDs in the LED package, the spreading ratio is further based on pitch distances to the immediate adjacent LEDs and the substrate boundary.

Abstract: Devices and methods including an LED and reflective die attach material are described herein. The devices can include a reflective substrate (e.g., a substrate that includes a silver layer) to which one or more LED die are attached using the die attach material. The die attach material extends beyond the periphery of the LED die to cover an area of the substrate surface.