Matrix material including an embedded dispersion of beads for a light-emitting device

• US 8,324,641 B2
• Filed: 06/29/2007
• Issued: 12/04/2012
• Est. Priority Date: 06/29/2007
• Status: Active Grant

• Current Assignee: LED Engin, Inc. (Ams-Osram AG)
• Original Assignee: Ledengin, Inc. (Ams-Osram AG)
• Inventors: Yan, Xiantao, Mei, Zequn
• Primary Examiner(s): Sandvik, Benjamin
• Assistant Examiner(s): Cruz, Leslie Pilar
• Application Number:
  US11/824,233
• Publication Number:
  US 20090001390A1
• Time in Patent Office: 1,985 Days
• Field of Search: 257/88, 257 98-100, 257E33056-E33059, 257/E33.061
• US Class Current: 257/98
• CPC Class Codes: H01L 25/0753 the devices being arranged next to each other
• CPC Class Codes: H01L 2924/00 Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
• CPC Class Codes: H01L 2924/0002 Not covered by any one of groups H01L24/00, H01L24/00 and H01L2224/00
• CPC Class Codes: H01L 2933/0091 Scattering means in or on the semiconductor body or semiconductor body package H01L33/22 takes precedence
• CPC Class Codes: H01L 33/50 Wavelength conversion elements
• CPC Class Codes: H01L 33/56 Materials, e.g. epoxy or silicone resin

Abstract

A light-emitting device has a light source disposed on a support. A matrix material including a dispersion of beads is disposed over the light source. The refractive index of the beads is different from the refractive index of the matrix material. The light source may include an LED. The matrix material may include a lens.

Claims

1. A light-emitting device comprising:

a body configured to support a light source, the body comprising;

a top surface, and

a cavity extending downward from the top surface, the cavity having a floor configured to receive a light source;

a light source bonded to the floor; and

a plurality of layers disposed between the light source and the top surface, the plurality of layers including;

a first layer adjacent to the light source, the first layer having a first refractive index, the first layer including a thermal insulating material, and

a second layer between the first layer including the thermal insulating layer and the top surface, the second layer having a second refractive index and including;

a matrix material; and

a dispersion of beads within the matrix material, the beads configured to scatter light provided by the light source, and

wherein the second refractive index is different than the first refractive index.

2. The light-emitting device of claim 1, wherein the floor is fabricated from a material having a thermal conductivity greater than 150 watts/meter-Kelvin.

3. The light-emitting device of claim 1, wherein the light source comprises red, green, and blue light-emitting elements, and the beads and first layer are transparent to the light emitted by the light emitting elements.

4. The light-emitting device of claim 1, wherein the light source comprises a blue light-emitting element, a red light-emitting element and two green light-emitting elements, and the beads are transparent to red, green, and blue light.

5. The light-emitting device of claim 1, wherein the floor is fabricated from aluminum nitride.

6. The light-emitting device of claim 1, wherein the matrix material includes a first glass, and the beads include a second glass having a higher melting point than the first glass.

7. The light-emitting device of claim 1, wherein at least a portion of the matrix includes a phosphor that absorbs light emitted by the light source, and the beads are transparent to the light emitted by both the light source and the phosphor.

8. The light-emitting device of claim 1, wherein the cavity includes a parabolic reflective surface.

9. The light-emitting device of claim 1, wherein the matrix material is disposed as a convex lens above the cavity and having a radius of curvature that does not exceed a cavity radius associated with the cavity.

10. The light-emitting device of claim 1, wherein the thermal insulating material has a thermal conductivity below 0.5 watts/meter-Kelvin.

11. The light-emitting device of claim 1, wherein the thermal insulating layer includes a polyimide.

12. The light-emitting device of claim 1, wherein the thermal insulating material has a glass transition temperature above 170 degrees Celsius .

13. The light-emitting device of claim 1, wherein the first refractive index is greater than a refractive index of the second layer.

14. The light-emitting device of claim 1, wherein the first refractive index is greater than 1.6.

15. The light-emitting device of claim 1, wherein the second refractive index is greater than about 1.44 and less than about 1.60.

16. The light-emitting device of claim 1, wherein the first refractive index is between 1.65 and 1.84.

17. The light-emitting device of claim 1, wherein the beads include silicone beads.

18. The light-emitting device of claim 1, wherein the light source is bonded to the floor with a die attach layer having a thermal conductivity greater than 0.5 watts/meter-Kelvin.

19. The light-emitting device of claim 1, wherein a diameter of the beads is greater than about 0.5 microns and less than about 10 microns, and an amount of beads dispersed within the matrix is between 2 and 10 percent by weight.

20. The light-emitting device of claim 1, wherein an amount of beads within the matrix material is greater than about 2 percent and less than about 10 percent by weight.

21. The light-emitting device of claim 1, wherein the plurality of layers includes a third layer attached to the second layer and opposite the first layer, the third layer having a lower refractive index than the second.

22. The light-emitting device of claim 21, wherein the first refractive index is 1.55, the second layer has a refractive index of 1.5, and the third layer has a refractive index of 1.45.

23. The light-emitting device of claim 21, wherein the third layer includes an adhesive layer, and the device further comprises a lens attached to the adhesive layer.

24. The light-emitting device of claim 23, wherein the body includes a socket configured to receive the lens, and the lens is inserted into the socket.

25. The light-emitting device of claim 23, wherein lens includes a Fresnel lens.

26. The light-emitting device of claim 23, wherein the adhesive layer includes silicone.