Light emitting device with a thermal insulating and refractive index matching material

• US 20060091788A1
• Filed: 01/13/2005
• Published: 05/04/2006
• Est. Priority Date: 10/29/2004
• Status: Active Grant

• Current Assignee: LED Engin, Inc. (Ams-Osram AG)
• Original Assignee: Ledengin, Inc. (Ams-Osram AG)
• Inventors: Yan, Xiantao
• Granted Patent: US 8,134,292 B2
• Time in Patent Office: Days
• US Class Current: 313/502
• 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 33/44 characterised by the coatings, e.g. passivation layer or anti-reflective coating
• CPC Class Codes: H01L 33/501 characterised by the materials, e.g. binder
• CPC Class Codes: H01L 33/507 the elements being in intimate contact with parts other than the semiconductor body or integrated with parts other than the semiconductor body
• CPC Class Codes: H01L 33/56 Materials, e.g. epoxy or silicone resin

Abstract

A light emitting device has a light emitting diode (LED) encapsulated by an encapsulant member. The encapsulant member includes a luminescent material, such as a phosphor, and a thermal insulating material. The thermal insulating material effectively insulates the luminescent material from the heat generated by the LED. A thermal conducting material is desirably placed in thermal contact with a back side of the LED to assist heat dissipation. The encapsulant member may be formed in two separate layers with the luminescent material forming a luminescent layer, and the thermal insulating material forming a thermal insulation layer disposed between the luminescent layer and the LED.

Claims

1. A light emitting device comprising:

a light emitting diode; and

an encapsulant member covering the top surface of the light emitting diode, the encapsulant member including a luminescent material and a thermal insulating material.

2. The light emitting device of claim 1 wherein the encapsulant member includes a luminescent layer comprising the luminescent material and a thermal insulation layer comprising the thermal insulation material and disposed between the luminescent layer and the top surface the light emitting diode.

3. The light emitting device of claim 2 wherein the luminescent layer is conformally disposed over an outer surface of the thermal insulation layer.

4. The light emitting device of claim 1 wherein the thermal insulating material is transparent to a wavelength emitted by the light emitting diode.

5. The light emitting device of claim 1 wherein the thermal insulating material is transparent to a wavelength in a range of about 200 nm-2000 nm.

6. The light emitting device of claim 1 wherein the thermal insulating material comprises a polymer.

7. The light emitting device of claim 1 wherein the thermal insulating material comprises a polyimide.

8. The light emitting device of claim 1 wherein the thermal insulating material comprises a ceramic.

9. The light emitting device of claim 1 wherein the thermal insulating material comprises a glass.

10. The light emitting device of claim 1 wherein the thermal insulating material has a thermal conductivity of no more than 0.5 W/m°

K.

11. The light emitting device of claim 1 wherein the thermal insulating material has a thermal conductivity of no more than 0.15 W/m°

K.

12. The light emitting device of claim 1 wherein the thermal insulating material has a glass transition temperature above 200°

C.

13. The light emitting device of claim 1 wherein the thermal insulating material has a glass transition temperature above 250°

C.

14. The light emitting device of claim 1 wherein the thermal insulating material has a refractive index greater than 1.8.

15. The light emitting device of claim 1 wherein the thermal insulating material has a refractive index in a range of 1.5-2.1.

16. The light emitting device of claim 1 wherein the thermal insulating material has a coefficient of thermal expansion no greater than 100 ppm/°

C.

17. The light emitting device of claim 1 wherein the thermal insulating material has a coefficient of thermal expansion no greater than 30 ppm/°

C.

18. The light emitting device of claim 1 capable of producing a power of about 1 watt or higher.

19. The light emitting device of claim 1 capable of producing a power of about 5 watts or higher.

20. The light emitting device of claim 1 capable of producing a power of about 10 watts of higher.

21. The light emitting device of claim 1 capable of producing a power of about 15 watts or higher.

22. The light emitting device of claim 1 wherein the light emitting diode is capable of producing a blue light.

23. The light emitting device of claim 22 wherein the luminescent material produces a white light when excited by the blue light.

24. The light emitting device of claim 1 wherein the luminescent material includes a phosphor.

25. The light emitting device of claim 1 wherein the luminescent material includes an yttrium aluminum garnet material.

26. The light emitting device of claim 1 wherein the luminescent material includes a terbium aluminum garnet material.

27. The light emitting device of claim 1 wherein the luminescent material includes a ZnSeS+ material.

28. The light emitting device of claim 1 wherein the luminescent material includes a silicon aluminum oxynitride material.

29. The light emitting device of claim 1 comprising one or more additional light emitting devices.

30. The light emitting device of claim 1 further comprising:

a thermal conducting material layer in thermal contact with a back side of the light emitting diode, the thermal conducting material layer having a thermal conductivity greater than 200 W/m°

K.

31. The light emitting device of claim 30 wherein the thermal conducting material layer includes a ceramic.

32. The light emitting device in claim 30 wherein the thermal conducting material layer has a thickness in a range of 0.2 mm-0.4 mm.

33. The light emitting device of claim 30 wherein the thermal conducting material layer includes aluminum nitride.

34. The light emitting device of claim 30 wherein the thermal conducting material layer includes aluminum oxide.

35. A light emitting diode package comprising:

a thermal conduction layer formed of a thermal conducting material having a thermal conductivity greater than 200 W/m°

K;

a light emitting diode bonded to the thermal conduction layer;

a thermal insulating material disposed over the light emitting diode; and

a luminescent material disposed over the thermal insulating material.

36. The light emitting diode package of claim 35 wherein the thermal insulating material forms a thermal insulation layer and the luminescent material is conformally disposed over an outer surface of the thermal insulation layer.

37. The light emitting diode package of claim 35 wherein the thermal conducting material includes a ceramic.

38. The light emitting diode package of claim 35 wherein the thermal conducting material includes aluminum nitride.

39. The light emitting diode package of claim 35 wherein the thermal conducting material includes aluminum oxide.

40. The light emitting diode package of claim 35 further comprising one or more additional light emitting diodes.

41. The light emitting diode package of claim 35 capable of producing a power of about 10 watts or higher.

42. A light emitting diode package for producing power 1 watt or higher, the light emitting diode package comprising:

a thermal conduction layer formed of a thermal conducting ceramic having a thermal conductivity greater than 200 W/m°

K;

a light emitting diode bonded to the thermal conduction layer; and

an encapsulant member covering a top surface of the light emitting diode, the encapsulant member including a luminescent material and a thermal insulating material.

43. The light emitting diode package of claim 42 wherein the thermal conducting ceramic includes aluminum nitride.

44. The light emitting diode package of claim 42 wherein the thermal conducting material includes aluminum oxide.

45. The light emitting diode package of claim 42 further comprising one or more additional light emitting diodes.