Method and apparatus for packaging phosphor-coated LEDs
View Patent ↗The present disclosure involves a method of packaging light-emitting diodes (LEDs). According to the method, a plurality of LEDs is provided over an adhesive tape. The adhesive tape is disposed on a substrate. In some embodiments, the substrate may be a glass substrate, a silicon substrate, a ceramic substrate, and a gallium nitride substrate. A phosphor layer is coated over the plurality of LEDs. The phosphor layer is then cured. The tape and the substrate are removed after the curing of the phosphor layer. A replacement tape is then attached to the plurality of LEDs. A dicing process is then performed to the plurality of LEDs after the substrate has been removed. The removed substrate may then be reused for a future LED packaging process.
1. A method of packaging light-emitting diodes (LEDs), comprising:
attaching a tape to a plurality of LEDs, the tape being disposed on a substrate;
coating a phosphor film around the plurality of LEDs;
curing the phosphor film;
removing the substrate after the curing; and
singulating the LEDs after the substrate has been removed.
2. The method of claim 1 , wherein the removing the substrate is performed in a manner such that the substrate can be recycled.
3. The method of claim 1 , further comprising: molding, before the substrate has been removed, a shape of the phosphor film with a molding stencil.
4. The method of claim 3 , wherein the molding is performed so that the phosphor film is shaped into a plurality of portions that each have one of the following shapes: a concave V-shape, a concave W-shape, and a concave U-shape, plurality of domes, and wherein each portion of the phosphor film is disposed over a different one of the LEDs, respectively.
5. The method of claim 4 , further comprising: forming a reflective layer over the phosphor film after the curing the phosphor film but before the removing the substrate.
6. The method of claim 3 , wherein the molding is performed so that the phosphor film is shaped into a plurality of portions that each have a convex dome-like shape, and wherein each portion of the phosphor film is disposed over a different one of the LEDs, respectively.
7. The method of claim 1 , wherein the singulating further comprises:
mechanically sawing an area between LEDs to separate the LEDs.
8. The method of claim 1 , further comprising:
binning a group of LEDs into a plurality of bins; and
thereafter selecting LEDs in a subset of the plurality of bins as the plurality of LEDs to be attached to the tape.
9. A method of fabricating light-emitting diodes (LEDs), comprising:
providing a plurality of LEDs disposed over an adhesive tape, the tape being disposed on a substrate, wherein the substrate includes one of: a glass substrate, a silicon substrate, a ceramic substrate, and a gallium nitride substrate;
coating a phosphor layer over the plurality of LEDs, the phosphor layer containing multiple sub-layers;
curing the phosphor layer;
forming a reflective layer over the phosphor layer;
de-taping the tape after the forming of the reflective layer;
removing the substrate after the forming of the reflective layer, the removing the substrate being performed in a manner such that the substrate is re-usable;
attaching a replacement tape to the plurality of LEDs; and
performing a dicing process to the plurality of LEDs after the substrate has been removed.
10. The method of claim 9 , wherein one of the sub-layers of the phosphor layer contains a gel mixed with phosphor particles, and the other one of the sub-layers contains a gel mixed with diffuser particles.
11. The method of claim 9 , wherein one of the sub-layers of the phosphor layer contains yellow phosphor particles mixed with a gel, and the other one of the sub-layers contains red phosphor particles mixed with a gel.
12. The method of claim 9 , wherein the reflective layer contains silver or aluminum.
13. The method of claim 9 , further comprising: molding the phosphor layer such that the phosphor layer has a plurality of predetermined segments that are each disposed over a respective one of the LEDs.
14. The method of claim 13 , wherein the predetermined segments each have one of: a concave V-shape, a concave U-shape, and a concave W-shape.
15. The method of claim 13 , wherein the predetermined segments each have a convex dome-like shape.
16. The method of claim 9 , wherein the providing comprises: selecting the plurality of LEDs from a group of LEDs that are associated with a plurality of bins, and wherein the plurality of LEDs selected all belong to a subset of the plurality of bins.
17. A method of packaging light-emitting diodes (LEDs), comprising:
attaching a plurality of LEDs to a substrate;
applying a photoconversion material on the LEDs, wherein the applying the photoconversion material comprises providing the photoconversion material such that the photoconversion material includes a first sub-layer and a second sub-layer located over the first sub-layer, the first sub-layer and the second sub-layer having different material compositions;
curing the photoconversion material;
thereafter removing the substrate; and
thereafter performing a dicing process to separate the plurality of LEDs into a plurality of LED dies each having a respective photoconversion material disposed thereon.
18. The method of claim 17 , wherein the attaching of the plurality of LED comprises:
providing an adhesive material on the substrate; and
attaching the plurality of LEDs to the adhesive material.
19. The method of claim 17 , wherein the curing is performed at a temperature in a range from about 130 degrees Celsius to about 170 degrees Celsius.
20. The method of claim 17 , wherein the removing of the substrate is performed such that the removed substrate can be reused in a fabrication of other LEDs.
21. The method of claim 20 , wherein the removing of the substrate comprises a laser lift-off process.
22. The method of claim 17 , further comprising: before the removing of the substrate, shaping the photoconversion material with a molding apparatus.
23. The method of claim 22 , wherein the shaping comprises shaping the photoconversion material on each LED into one of the following shapes: a concave V-shape, a concave W-shape, a concave U-shape, and a dome shape.
24. The method of claim 17 , further comprising: forming a reflective layer over the photoconversion material after the curing of the photoconversion material but before the removing of the substrate.
25. The method of claim 17 , wherein the dicing process is performed between adjacent LEDs.
26. The method of claim 17 , wherein:
the first sub-layer contains phosphor particles; and
the second sub-layer contains diffuser particles.
27. The method of claim 17 , further comprising: after the performing of the dicing process, attaching a housing to one or more of the LED dies.