Methods for packaging a light emitting device and packaged light emitting devices

• US 20050218421A1
• Filed: 01/27/2005
• Published: 10/06/2005
• Est. Priority Date: 03/31/2004
• Status: Active Grant

• Current Assignee: CREE Led Incorporated (Smart Global Holdings Incorporated)
• Original Assignee: CREE Incorporated (Wolfspeed, Inc.)
• Inventors: Ibbetson, James, Coleman, Thomas G., Leung, Michael, Negley, Gerald H., Tarsa, Eric, Andrews, Peter
• Granted Patent: US 7,279,346 B2
• Time in Patent Office: Days
• US Class Current: 257/100
• CPC Class Codes: H01L 2924/00012 Relevant to the scope of the group, the symbol of which is combined with the symbol of this group
• CPC Class Codes: H01L 2924/181 Encapsulation
• CPC Class Codes: H01L 33/52 Encapsulations
• CPC Class Codes: H01L 33/58 Optical field-shaping elements
• CPC Class Codes: H01L 33/60 Reflective elements

Abstract

Methods of packaging a semiconductor light emitting device positioned in a reflective cavity are provided. A first quantity of encapsulant material is dispensed into the reflective cavity including the light emitting device therein and the first quantity of encapsulant in the reflective cavity is cured. A second quantity of encapsulant material is dispensed onto the cured first quantity of encapsulant material. A lens is positioned in the reflective cavity on the dispensed second quantity of encapsulant material. The dispensed second quantity of encapsulant material is cured to attach the lens in the reflective cavity.

Claims

1. A method of packaging a semiconductor light emitting device, comprising:

dispensing a first quantity of encapsulant material into a reflective cavity including the light emitting device;

curing the first quantity of encapsulant material in the reflective cavity;

dispensing a second quantity of encapsulant material onto the cured first quantity of encapsulant material;

positioning a lens in the reflective cavity on the dispensed second quantity of encapsulant material;

curing the dispensed second quantity of encapsulant material to attach the lens in the reflective cavity.

2. The method of claim 1 wherein dispensing a first quantity of encapsulant material into the reflective cavity including the light emitting device includes:

dispensing a first portion of the first quantity of encapsulant material into the reflective cavity including the light emitting device, the first portion being sufficient to wet the light emitting device without filling the reflective cavity to a level exceeding a height of the light emitting device; and

dispensing a second portion of the first quantity of encapsulant material onto the first portion of the first quantity of encapsulant material.

3. The method of claim 1 wherein dispensing a first quantity of encapsulant material into the reflective cavity including the light emitting device includes:

dispensing a first portion of the first quantity of encapsulant material into the reflective cavity including the light emitting device, the first portion of the first quantity being sufficient to substantially cover the light emitting device without forming any air pockets in the encapsulant material;

dispensing a second portion of the first quantity of encapsulant material onto the first portion of the first quantity of encapsulant material.

4. The method of claim 3 wherein the second portion is about twice the first portion.

5. The method of claim 4 wherein the second quantity is about equal to the first portion of the first quantity.

6. The method of claim 5 wherein the first portion is sufficient to fill the reflective cavity to a height of about 250 microns.

7. The method of claim 3 wherein curing the first quantity of encapsulant material includes curing the first portion of the first quantity of encapsulant material before dispensing the second portion of the first quantity of encapsulant material and wherein the first portion of the first quantity of encapsulant material includes a phosphor and wherein the second portion of the first quantity of encapsulant material is substantially free of phosphor.

8. The method of claim 1 wherein mounting the light emitting device comprises mounting the light emitting device at about a midpoint of the reflective cavity and wherein dispensing a first and a second quantity of encapsulant material comprise dispensing the encapsulant material at a point displaced from the midpoint towards a sidewall of the cavity so that the encapsulant material is not dispensed directly onto the light emitting device.

9. The method of claim 1 wherein the encapsulant material comprises a silicone gel.

10. The method of claim 1 wherein positioning the lens comprises advancing the lens into the reflective cavity until it contacts the cured first quantity of encapsulant material and wherein dispensing the first quantity of encapsulant material comprises dispensing a first quantity of encapsulant material sufficient to establish a desired position for the lens in the reflective cavity.

11. The method of claim 1 wherein the first quantity of encapsulant Material includes a phosphor and wherein the second quantity of encapsulant material is substantially free of phosphor.

12. The method of claim 1 wherein the light emitting device comprises a light emitting diode (LED).

13. The method of claim 1 further comprising mounting the light emitting device on a bottom surface of the reflective cavity.

14. The method of claim 3 wherein dispensing a first portion of the first quantity of encapsulant material includes forming a bead of the encapsulant material on an end of a dispenser and contacting the formed bead with the reflective cavity and/or the light emitting device to dispense the bead from the dispenser.

15. A method of packaging a semiconductor light emitting device, comprising:

providing the light emitting device on a bottom surface of a reflective cavity, the light emitting device having a height relative to the bottom surface;

dispensing a first quantity of encapsulant material into the reflective cavity including the light emitting device, the first quantity being sufficient to wet the light emitting device without filling the reflective cavity to a level exceeding the height of the light emitting device;

dispensing a second quantity of encapsulant material onto the first quantity of encapsulant material;

curing the dispensed encapsulant material.

16. The method of claim 15 wherein the second quantity is about twice the first quantity.

17. The method of claim 16 wherein the first quantity is sufficient to fill the reflective cavity to a height of about 250 microns.

18. The method of claim 15 wherein curing the dispensed encapsulant material includes curing the first quantity of encapsulant material before dispensing the second quantity of encapsulant material and wherein the first quantity of encapsulant material includes a phosphor and wherein the second quantity of encapsulant material is substantially free of phosphor.

19. The method of claim 15 wherein dispensing a first quantity of encapsulant material includes forming a bead of the encapsulant material on an end of a dispenser and contacting the formed bead with the reflective cavity and/or the light emitting device to dispense the bead from the dispenser.

20. A method of packaging a semiconductor light emitting device, comprising:

providing the light emitting device on a bottom surface of a reflective cavity;

dispensing a first quantity of encapsulant material into the reflective cavity including the light emitting device, the first quantity being sufficient to substantially cover the light emitting device without forming any air pockets in the encapsulant material;

curing the dispensed encapsulant material.

21. The method of claim 20 wherein curing the dispensed encapsulant material is preceded by dispensing a second quantity of encapsulant material onto the first quantity of encapsulant material.

22. The method of claim 20 wherein the second quantity is about twice the first quantity.

23. The method of claim 22 wherein the first quantity is sufficient to fill the reflective cavity to a height of about 250 microns.

24. The method of claim 20 wherein curing the dispensed encapsulant material includes curing the first quantity of encapsulant material before dispensing the second quantity of encapsulant material and wherein the first quantity of encapsulant material includes a phosphor and wherein the second quantity of encapsulant material is substantially free of phosphor.

25. The method of claim 20 wherein dispensing a first quantity of encapsulant material includes forming a bead of the encapsulant material on an end of a dispenser and contacting the formed bead with the reflective cavity and/or the light emitting device to dispense the bead from the dispenser.

26. A method of packaging a semiconductor light emitting device, comprising:

dispensing a first quantity of encapsulant material having a first index of refraction into a reflective cavity including the light emitting device;

curing the first quantity of encapsulant material;

dispensing a second quantity of encapsulant material having a second index of refraction, different from the first index of refraction, onto the cured first quantity of encapsulant material, wherein the first and second index of refraction are selected to provide a buried lens in the reflective cavity; and

curing the second quantity of encapsulant material to form the buried lens.

27. The method of claim 26 wherein the light emitting device comprises a light emitting diode (LED).

28. The method of claim 26 wherein dispensing a first quantity of encapsulant material includes:

dispensing a first portion of the first quantity of encapsulant material into the reflective cavity including the light emitting device, the first portion being sufficient to wet the light emitting device without filling the reflective cavity to a level exceeding a height of the light emitting device; and

dispensing a second portion of the first quantity of encapsulant material onto the first portion of the first quantity of encapsulant material.

29. The method of claim 26 wherein dispensing a first quantity of encapsulant material includes:

dispensing a first portion of the first quantity of encapsulant material into the reflective cavity including the light emitting device, the first portion of the first quantity being sufficient to substantially cover the light emitting device without forming any air pockets in the encapsulant material;

dispensing a second portion of the first quantity of encapsulant material onto the first portion of the first quantity of encapsulant material.

30. A packaged semiconductor light emitting device, comprising:

a reflector having a lower sidewall portion defining a reflective cavity;

a light emitting device positioned in the reflective cavity;

a first quantity of cured encapsulant material having a first index of refraction in the reflective cavity including the light emitting device; and

a second quantity of cured encapsulant material having a second index of refraction, different from the first index of refraction, on the first quantity of cured encapsulant material, the first and second index of refraction being selected to provide a buried lens in the reflective cavity.

31. The device of claim 30 wherein the light emitting device comprises a light emitting diode (LED).