Abstract:
Optical elements (130) are attached to a support film (110) at select locations, the select locations corresponding to locations of light emitting elements (140) on another substrate, e.g. the substrate of the title (150). The film is placed on the substrate containing the light emitting elements such that the optical elements are in contact with their corresponding light emitting elements. The optical elements are laminated to the light emitting elements, and the support film is removed. The optical elements may include wavelength conversion elements, lens elements, combinations of elements, and so on. Other elements, such as conductors and reflectors may also be positioned on the laminate film.
Abstract:
One or more LED dice are mounted on a support structure. The support structure may be a submount with the LED dice already electrically connected to leads on the submount. A mold has indentations in it corresponding to the positions of the LED dice on the support structure. The indentations are filled with a liquid optically transparent material, such as silicone, which when cured forms a lens material. The shape of the indentations will be the shape of the lens. The mold and the LED dice/support structure are brought together so that each LED die resides within the liquid silicone in an associated indentation. The mold is then heated to cure (harden) the silicone. The mold and the support structure are then separated, leaving a complete silicone lens over each LED die. This over molding process may be repeated with different molds to create concentric shells of lenses. Each concentric lens may have a different property, such as containing a phosphor, providing a special radiation pattern, having a different hardness value, or curable by a different technique (e.g., UV vs. heat).
Abstract:
LED dies are mounted a single submount tile (or wafer). The LED dies have a light emitting top surface. A uniformly thick layer of UV sensitive silicone infused with phosphor is then deposited over the tile, including over the tops and sides of the LED dies. Only the silicone/phosphor over the top and sides of the LED dies is desired, so the silicone/phosphor directly on the tile needs to be removed. The silicone/phosphor layer is then masked to expose the areas that are to remain to UV light, which creates a cross-linked silicone. The unexposed silicone/phosphor layer is then dissolved with a solvent and removed from the tile surface. The silicone/phosphor layer may be defined to expose a wire bond electrode on the LED dies. The tile is ultimately singulated to produce individual phosphor-converted LEDs.
Abstract:
A device includes a semiconductor structure comprising a light emitting layer disposed between an n-type region and a p-type region. A luminescent material is positioned in a path of light emitted by the light emitting layer. A thermal coupling material is disposed in a transparent material. The thermal coupling material has a thermal conductivity greater than a thermal conductivity of the transparent material. The thermal coupling material is positioned to dissipate heat from the luminescent material.
Abstract:
A device includes a semiconductor structure comprising a light emitting layer disposed between an n-type region and a p-type region. A luminescent material is positioned in a path of light emitted by the light emitting layer. A thermal coupling material is disposed in a transparent material. The thermal coupling material has a thermal conductivity greater than a thermal conductivity of the transparent material. The thermal coupling material is positioned to dissipate heat from the luminescent material.
Abstract:
In one embodiment, a flip chip LED is formed with a high density of gold posts extending from a bottom surface of its n-layer and p-layer. The gold posts are bonded to submount electrodes. An underfill material is then molded to fill the voids between the bottom of the LED and the submount. The underfill comprises a silicone molding compound base and about 70-80%, by weight, alumina (or other suitable material). Alumina has a thermal conductance that is about 25 times better than that of the typical silicone underfill, which is mostly silica. The alumina is a white powder. The underfill may also contain about 5-10%, by weight, TiO2 to increase the reflectivity. LED light is reflected upward by the reflective underfill, and the underfill efficiently conducts heat to the submount. The underfill also randomizes the light scattering, improving light extraction. The distributed gold posts and underfill support the LED layers during a growth substrate lift-off process.
Abstract:
After flip chip LEDs are mounted on a submount wafer and their growth substrates removed, a phosphor plate is affixed to the exposed top surface of each LED. A reflective material, such as silicone containing at least 5% TiO2 powder, by weight, is then spun over or molded over the wafer to cover the phosphor plates and the sides of the LEDs. The top surface of the reflective material is then etched using microbead blasting to expose the top of the phosphor plates and create a substantially planar reflective layer over the wafer surface. Lenses may then be formed over the LEDs. The wafer is then singulated. The reflective material reflects all side light back into the LED and phosphor plate so that virtually all light exits the top of the phosphor plate to improve the light emission characteristics.
Abstract:
In one embodiment, sub-micron size granules of TiO2, ZrO2, or other white colored non-phosphor inert granules are mixed with a silicone encapsulant and applied over an LED. In one experiment, the granules increased the light output of a GaN LED more than 5% when the inert material was between about 2.5-5% by weight of the encapsulant. Generally, a percentage of the inert material greater than 5% begins to reduce the light output. If the LED has a yellowish YAG phosphor coating, the white granules in the encapsulant make the LED appear whiter when the LED is in an off state, which is a more pleasing color when the LED is used as a white light flash in small cameras. The addition of the granules also reduces the variation of color temperature over the view angle and position over the LED, which is important for a camera flash and projection applications.
Abstract:
In one embodiment, sub-micron size granules of TiO2, ZrO2, or other white colored non-phosphor inert granules are mixed with a silicone encapsulant and applied over an LED. In one experiment, the granules increased the light output of a GaN LED more than 5% when the inert material was between about 2.5-5% by weight of the encapsulant. Generally, a percentage of the inert material greater than 5% begins to reduce the light output. If the LED has a yellowish YAG phosphor coating, the white granules in the encapsulant make the LED appear whiter when the LED is in an off state, which is a more pleasing color when the LED is used as a white light flash in small cameras. The addition of the granules also reduces the variation of color temperature over the view angle and position over the LED, which is important for a camera flash and projection applications.
Abstract:
A method according to embodiments of the invention includes positioning a flexible film (48) over a wafer of semiconductor light emitting devices, each semiconductor light emitting device including a semiconductor structure (13) including a light emitting layer sandwiched between an n-type region and a p-type region. The wafer of semiconductor light emitting devices is bonded to a substrate (50) via the flexible film (48). After bonding, the flexible film (48) is in direct contact with the semiconductor structures (13). The method further includes dividing the wafer after bonding the wafer to the substrate (50).