Integrated heat spreaders for light emitting devices (LEDs) and related assemblies

• US 7,808,013 B2
• Filed: 10/31/2006
• Issued: 10/05/2010
• Est. Priority Date: 10/31/2006
• Status: Active Grant

• Current Assignee: Creeled Incorporated
• Original Assignee: CREE Incorporated (Wolfspeed, Inc.)
• Inventors: Mendendorp, Nicholas W. Jr., Andrews, Peter
• Primary Examiner(s): NGUYEN, CUONG QUANG
• Application Number:
  US11/590,480
• Publication Number:
  US 20080099770A1
• Time in Patent Office: 1,435 Days
• Field of Search: 257 78-103, 257/675, 257/E33.072
• US Class Current: 257/99
• CPC Class Codes: H01L 2224/32225 the item being non-metallic, e.g. insulating substrate with or without metallisation
• CPC Class Codes: H01L 2224/48091 Arched
• CPC Class Codes: H01L 2224/48227 connecting the wire to a bond pad of the item
• CPC Class Codes: H01L 2224/73265 Layer and wire connectors
• 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 2924/00012 Relevant to the scope of the group, the symbol of which is combined with the symbol of this group
• CPC Class Codes: H01L 2924/00014 the subject-matter covered by the group, the symbol of which is combined with the symbol of this group, being disclosed without further technical details
• CPC Class Codes: H01L 2924/01019 Potassium [K]
• CPC Class Codes: H01L 2924/01025 Manganese [Mn]
• CPC Class Codes: H01L 2924/01057 Lanthanum [La]
• CPC Class Codes: H01L 2924/01078 Platinum [Pt]
• CPC Class Codes: H01L 2924/01079 Gold [Au]
• CPC Class Codes: H01L 2924/01087 Francium [Fr]
• CPC Class Codes: H01L 2924/1815 Shape
• CPC Class Codes: H01L 2924/19107 off-chip wires
• CPC Class Codes: H01L 2924/3011 Impedance
• CPC Class Codes: H01L 33/62 Arrangements for conducting electric current to or from the semiconductor body, e.g. lead-frames, wire-bonds or solder balls
• CPC Class Codes: H01L 33/64 Heat extraction or cooling elements
• CPC Class Codes: H01L 33/647 the elements conducting electric current to or from the semiconductor body
• CPC Class Codes: H05K 1/0206 by printed thermal vias
• CPC Class Codes: H05K 2201/09781 : Dummy conductors, i.e. not used for normal transport of current; Dummy electrodes of components
• CPC Class Codes: H05K 2201/10106 : Light emitting diode [LED]
• CPC Class Codes: H05K 2203/049 : Wire bonding

Abstract

A light emitting device (LED) assembly may include an electrically insulating substrate and a thermally conductive layer on a surface of the insulating substrate. A light emitting device may be on the thermally conductive layer so that the thermally conductive layer is between the light emitting device and the electrically insulating substrate. Moreover, the thermally conductive layer may extend beyond an edge of the light emitting device in at least one direction a distance greater than half of a width of the light emitting device.

Claims

1. A light emitting device (LED) assembly comprising:

an electrically insulating substrate;

a continuous thermally conductive layer adjacent a surface of the electrically insulating substrate;

a light emitting device adjacent the continuous thermally conductive layer so that the continuous thermally conductive layer is between an entirety of the light emitting device and the electrically insulating substrate, wherein the continuous thermally conductive layer extends beyond an edge of the light emitting device in at least one direction a distance greater than half of a width of the light emitting device; and

a plurality of thermally conductive vias through the electrically insulating substrate, wherein the plurality of thermally conductive vias are thermally and electrically coupled to the continuous thermally conductive layer and wherein portions of the electrically insulating substrate adjacent the light emitting device are free of the plurality of thermally conductive vias.

2. A light emitting device assembly according to claim 1, wherein the plurality of thermally conductive vias extend from the continuous thermally conductive layer through the electrically insulating substrate.

3. A light emitting device assembly according to claim 1, wherein the continuous thermally conductive layer comprises at least one of a metal layer, a ceramic layer, and/or a semiconductor layer.

4. A light emitting device assembly according to claim 3, wherein the continuous thermally conductive layer comprises a copper layer.

5. A light emitting device assembly according to claim 1, wherein the continuous thermally conductive layer is electrically conductive, the light emitting device assembly further comprising:

a first electrical coupling between a first terminal of the light emitting device and the continuous thermally conductive layer;

an electrode on the electrically insulating substrate wherein the electrode and the continuous thermally conductive layer are electrically isolated; and

a second electrical coupling between a second terminal of the light emitting device and the electrode.

6. A light emitting device assembly according to claim 1, wherein the continuous thermally conductive layer is electrically conductive and wherein the light emitting device includes first and second terminals on a surface of the light emitting device opposite the continuous thermally conductive layer, the light emitting device assembly further comprising:

first and second electrodes, each of which is electrically isolated from the continuous thermally conductive layer;

a first electrical coupling between the first terminal of the light emitting device and the first electrode; and

a second electrical coupling between the second terminal of the light emitting device and the second electrode.

7. A light emitting device assembly according to claim 1, wherein the continuous thermally conductive layer is electrically conductive and wherein the thermally conductive layer comprises a substantially circular thermally conductive layer.

8. A light emitting device according to claim 1 wherein the continuous thermally conductive layer extends beyond opposing edges of the light emitting device a distance greater than half of a width of the light emitting device.

9. A light emitting device according to claim 1 wherein the continuous thermally conductive layer extends beyond an edge of the light emitting device in at least one direction a distance that is greater than a width of the light emitting device.

10. A light emitting device assembly according to claim 1 wherein the thermally conductive layer comprises a first thermally conductive layer, the light emitting device further comprising:

a second thermally conductive layer adjacent a surface of the electrically insulating substrate opposite the first thermally conductive layer wherein the electrically insulating substrate is between the light emitting device and the second thermally conductive layer in a direction perpendicular with respect to a surface of the electrically insulating substrate and wherein all portions of the electrically insulating substrate between the light emitting device and the second thermally conductive layer in the direction perpendicular with respect to the surface of the electrically insulating substrate are free of the thermally conductive vias so that portions of the light emitting device and the first and second thermally conductive layers are aligned in the direction perpendicular with respect to the surface of the electrically insulating substrate.

11. A light emitting device assembly according to claim 1 wherein the electrically insulating substrate comprises a ceramic substrate.

12. A light emitting device assembly according to claim 1 further comprising:

a lens on the light emitting device so that the light emitting device is between the lens and the ceramic substrate.

13. A light emitting device assembly according to claim 1 further comprising:

a reflector on the ceramic substrate around the light emitting device.

14. A light emitting device (LED) assembly comprising:

an electrically insulating substrate;

a thermally conductive layer adjacent a surface of the electrically insulating substrate, wherein the thermally conductive layer is electrically conductive and wherein the thermally conductive layer comprises a substantially circular thermally conductive layer wherein the substantially circular thermally conductive layer comprises a plurality of notches around a perimeter thereof;

a light emitting device adjacent the thermally conductive layer so that the thermally conductive layer is between the light emitting device and the electrically insulating substrate, wherein the thermally conductive layer extends beyond an edge of the light emitting device in at least one direction a distance greater than half of a width of the light emitting device; and

a plurality of thermally conductive vias through the electrically insulating substrate, wherein the plurality of thermally conductive vias are thermally coupled to the thermally conductive layer and wherein portions of the electrically insulating substrate adjacent the light emitting device are free of the plurality of thermally conductive vias.

15. A light emitting device assembly according to claim 14, wherein each of the notches extends radially from the perimeter of the thermally conductive layer toward the light emitting device.

16. A light emitting device (LED) assembly comprising:

an electrically insulating substrate;

a thermally conductive layer adjacent a surface of the electrically insulating substrate, wherein the thermally conductive layer is electrically conductive and wherein the thermally conductive layer comprises a substantially circular thermally conductive layer;

a light emitting device adjacent the thermally conductive layer so that the thermally conductive layer is between the light emitting device and the electrically insulating substrate, wherein the thermally conductive layer extends beyond an edge of the light emitting device in at least one direction a distance greater than half of a width of the light emitting device;

a plurality of thermally conductive vias through the electrically insulating substrate, wherein the plurality of thermally conductive vias are thermally coupled to the thermally conductive layer and wherein portions of the electrically insulating substrate adjacent the light emitting device are free of the plurality of thermally conductive vias; and

a conductive trace on the electrically insulating substrate, wherein the conductive trace extends from the substantially circular thermally conductive layer.

17. A light emitting device assembly comprising:

an electrically insulating substrate having opposing first and second surfaces;

a first thermally conductive layer adjacent the first surface of the electrically insulating substrate wherein the first thermally conductive layer is electrically conductive and wherein the first thermally conductive layer comprises a substantially circular first thermally conductive layer;

a second thermally conductive layer adjacent the second surface of the electrically insulating substrate so that the electrically insulating substrate is between the first and second thermally conductive layers;

a light emitting device adjacent the first thermally conductive layer so that portions of the first thermally conductive layer are between the light emitting device and the electrically insulating substrate in a direction perpendicular with respect to a surface of the electrically insulating substrate, and so that the electrically insulating substrate is between the light emitting device and portions of the second thermally conductive layer in the direction perpendicular with respect to the surface of the electrically insulating substrate; and

a plurality of thermally conductive vias, wherein the plurality of thermally conductive vias are thermally coupled between the first and second thermally conductive layers and wherein portions of the electrically insulating substrate between the light emitting device and the second thermally conductive layer are free of the thermally conductive vias; and

a conductive trace on the electrically insulating substrate, wherein the conductive trace extends from the substantially circular first thermally conductive layer.

18. A light emitting device assembly according to claim 17, wherein the plurality of thermally conductive vias extend from the first thermally conductive layer through the electrically insulating substrate to the second thermally conductive layer.

19. A light emitting device assembly according to claim 17, wherein the first thermally conductive layer extends beyond an edge of the light emitting device in at least one direction a distance greater than half of a width of the light emitting device.

20. A light emitting device assembly according to claim 17 wherein the first thermally conductive layer extends beyond any edge of the light emitting device in at least one direction a distance greater than a width of the light emitting device.

21. A light emitting device assembly according to claim 17 wherein the first thermally conductive layer extends beyond opposing edges of the light emitting device a distance greater than half of a width of the light emitting device.

22. A light emitting device assembly according to claim 17, wherein each of the first and second thermally conductive layers comprises at least one of a metal layer, a ceramic layer, and/or a semiconductor layer.

23. A light emitting device assembly according to claim 22, wherein the first thermally conductive layer and/or second thermally conductive layer comprises a copper layer.

24. A light emitting device assembly according to claim 22 wherein the first thermally conductive layer is electrically isolated from first and second terminals of the LED.

25. A light emitting device assembly according to claim 17, wherein the first and second thermally conductive layers are electrically conductive, the light emitting device assembly further comprising:

a first electrical coupling between a first terminal of the light emitting device and the first thermally conductive layer;

an electrode on the electrically insulating substrate wherein the terminal and the first and second thermally conductive layers are electrically isolated; and

a second electrical coupling between a second terminal of the light emitting device and the electrode.

26. A light emitting device assembly according to claim 17, wherein the first and second thermally conductive layers are electrically conductive, the light emitting device assembly further comprising:

first and second electrodes, each of which is electrically isolated from the first and second thermally conductive layers;

a first electrical coupling between a first terminal of the light emitting device and the first electrode; and

a second electrical coupling between a second terminal of the light emitting device and the second electrode.

27. A light emitting device assembly according to claim 17 wherein all portions of the electrically insulating substrate between the light emitting device and the second thermally conductive layer in the direction perpendicular with respect to the surface of the electrically insulating substrate are free of the plurality of thermally conductive vias.

28. A light emitting device assembly according to claim 17 wherein the electrically insulating substrate comprises a ceramic substrate.

29. A light emitting device assembly according to claim 17 further comprising:

a lens on the light emitting device so that the light emitting device is between the lens and the ceramic substrate.

30. A light emitting device assembly according to claim 17 further comprising:

a reflector on the ceramic substrate around the light emitting device.

31. A light emitting device assembly according to claim 17 wherein all portions of the electrically insulating substrate within an area defined by a perimeter of the light emitting device are free of the thermally conductive vias.

32. A light emitting device assembly comprising:

an electrically insulating substrate having opposing first and second surfaces;

a first thermally conductive layer adjacent the first surface of the electrically insulating substrate wherein the first thermally conductive layer is electrically conductive and wherein the first thermally conductive layer comprises a substantially circular first thermally conductive layer comprising a plurality of notches around a perimeter thereof;

a second thermally conductive layer adjacent the second surface of the electrically insulating substrate so that the electrically insulating substrate is between the first and second thermally conductive layers;

a light emitting device adjacent the first thermally conductive layer so that portions of the first thermally conductive layer are between the light emitting device and the electrically insulating substrate in a direction perpendicular with respect to a surface of the electrically insulating substrate, and so that the electrically insulating substrate is between the light emitting device and portions of the second thermally conductive layer in the direction perpendicular with respect to the surface of the electrically insulating substrate; and

a plurality of thermally conductive vias, wherein the plurality of thermally conductive vias are thermally coupled between the first and second thermally conductive layers and wherein portions of the electrically insulating substrate between the light emitting device and the second thermally conductive layer are free of the thermally conductive vias.

33. A light emitting device (LED) assembly comprising:

an electrically insulating substrate;

a substantially circular thermally conductive layer adjacent a surface of the insulating substrate; and

a light emitting device adjacent the substantially circular thermally conductive layer so that the substantially circular thermally conductive layer is between the light emitting device and the electrically insulating substrate, wherein an edge of the substantially circular thermally conductive layer extends laterally beyond an edge of the light emitting device;

wherein the substantially circular thermally conductive layer includes a plurality of notches around a perimeter thereof.

34. A light emitting device assembly according to claim 33, wherein a first portion of the substantially circular thermally conductive layer is electrically isolated from a second portion of the substantially circular thermally conductive layer.

35. A light emitting device assembly according to claim 33, wherein each of the notches extends radially from the perimeter of the substantially circular thermally conductive layer toward the light emitting device.

36. A light emitting device assembly according to claim 33, further comprising:

a conductive trace on the electrically insulating substrate, wherein the conductive trace extends from the substantially circular thermally conductive layer.

37. A light emitting device assembly according to claim 33 wherein the substantially circular thermally conductive layer extends beyond an edge of the light emitting device a distance greater than half of a width of the light emitting device.

38. A light emitting device assembly according to claim 33 wherein the substantially circular thermally conductive layer extends beyond an edge of the light emitting device a distance greater than a width of the light emitting device.

39. A light emitting device assembly according to claim 33 wherein the substantially circular thermally conductive layer extends beyond opposing edges of the light emitting device a distance greater than half of a width of the light emitting device.

40. A light emitting device assembly according to claim 33, wherein the substantially circular thermally conductive layer comprises at least one of a metal layer, a ceramic layer, and/or a semiconductor layer.

41. A light emitting device assembly according to claim 33, further comprising:

a second thermally conductive layer adjacent a second surface of the electrically insulating substrate so that the electrically insulating substrate is between the substantially circular thermally conductive layer and the second thermally conductive layer; and

a plurality of thermally conductive vias, wherein the plurality of thermally conductive vias are thermally and physically coupled between the substantially circular thermally conductive layer and the second thermally conductive layer and wherein portions of the substrate between the light emitting device and the second thermally conductive layer are free of the plurality of thermally conductive vias.

42. A light emitting device according to claim 41 wherein first and second terminals of the light emitting device are electrically isolated from the substantially circular thermally conductive layer.

43. A light emitting device assembly according to claim 33, further comprising:

a second thermally conductive layer adjacent a second surface of the electrically insulating substrate so that the electrically insulating substrate is between the substantially circular thermally conductive layer and the second thermally conductive layer; and

a plurality of thermally conductive vias, wherein the plurality of thermally conductive vias are thermally and physically coupled between the substantially circular thermally conductive layer and the second thermally conductive layer and wherein the plurality of thermally conductive vias extend through portions of the electrically insulating substrate outside a region of the electrically insulating substrate defined by a periphery of the light emitting device.

44. A light emitting device assembly according to claim 33, wherein the substantially circular thermally conductive layer extends continuously from the light emitting device to portions of the perimeter between each of the notches.

45. A light emitting device assembly according to claim 41 wherein all portions of the electrically insulating substrate between the light emitting device and the second thermally conductive layer in a direction perpendicular with respect to a surface of the electrically insulating substrate are free of the plurality of thermally conducive vias.

46. A light emitting device assembly according to claim 43 wherein all portions of the electrically insulating substrate between the light emitting device and the second thermally conductive layer in a direction perpendicular with respect to a surface of the electrically insulating substrate are free of the plurality of thermally conductive vias.

47. A light emitting device assembly according to claim 33 wherein the electrically insulating substrate comprises a ceramic substrate.

48. A light emitting device assembly according to claim 33 further comprising:

a lens on the light emitting device so that the light emitting device is between the lens and the ceramic substrate.

49. A light emitting device assembly according to claim 33 further comprising:

a reflector on the ceramic substrate around the light emitting device.

50. A light emitting device (LED) assembly comprising:

an electrically insulating ceramic substrate having opposing first and second faces;

a first thermally conductive layer on a first surface of the ceramic substrate;

a second thermally conductive layer on the second surface of the ceramic substrate so that the ceramic substrate is between the first and second thermally conductive layers, wherein the second thermally conductive layer is electrically isolated from the first thermally conductive layer; and

a light emitting device on the first thermally conductive layer so that the first thermally conductive layer is between the light emitting device and the ceramic substrate, wherein portions of the light emitting device and the first and second thermally conductive layers are aligned in a direction perpendicular with respect to a surface of the light emitting device wherein the first thermally conductive layer comprises a continuous thermally conductive layer between an entirety of the light emitting device and the ceramic substrate.

51. A light emitting device assembly according to claim 50 wherein the first and second thermally conductive layers comprise respective first and second thermally conductive metal layers.

52. A light emitting device assembly according to claim 51 wherein the light emitting device is a vertical light emitting device with a first terminal on a surface of the light emitting device adjacent the first thermally conductive metal layer and a second terminal on a surface of the light emitting device opposite the first thermally conductive metal layer, the light emitting assembly further comprising:

a wire bond pad spaced apart from the first thermally conductive metal layer on the first surface of the ceramic substrate; and

a wire bond providing an electrical connection between the second terminal of the light emitting device and the wire bond pad.

53. A light emitting device assembly according to claim 52 further comprising:

first and second electrodes on the second face of the electrically insulating ceramic substrate wherein the first and second electrodes are spaced apart and electrically isolated from the second thermally conductive metal layer;

a first electrically conductive via providing electrical coupling between the first thermally conductive metal layer and the first electrode through the ceramic substrate; and

a second electrically conductive via providing electrical coupling between the wire bond pad and the second electrode through the ceramic substrate.

54. A light emitting device assembly according to claim 50 wherein the ceramic substrate comprises an alumina substrate.

55. A light emitting device assembly according to claim 50 further comprising:

a lens on the light emitting device so that the light emitting device is between the lens and the ceramic substrate.

56. A light emitting device assembly according to claim 50 further comprising:

a reflector on the ceramic substrate around the light emitting device.

57. A light emitting device assembly comprising:

an electrically insulating substrate having opposing first and second surfaces;

a first thermally conductive layer adjacent the first surface of the electrically insulating substrate;

a second thermally conductive layer adjacent the second surface of the electrically insulating substrate so that the electrically insulating substrate is between the first and second thermally conductive layers;

a light emitting device adjacent the first thermally conductive layer so that portions of the first thermally conductive layer are between the light emitting device and the electrically insulating substrate in a direction perpendicular with respect to a surface of the electrically insulating substrate, and so that the electrically insulating substrate is between the light emitting device and portions of the second thermally conductive layer in the direction perpendicular with respect to the surface of the electrically insulating substrate so that portions of the light emitting device and the first and second thermally conductive layers are aligned in the direction perpendicular with respect to the surface of the electrically insulating substrate; and

a plurality of thermally conductive vias, wherein the plurality of thermally conductive vias are thermally coupled between the first and second thermally conductive layers and wherein portions of the electrically and the second thermally conductive layer are free of the thermally conductive vias;

wherein the plurality of thermally conductive vias are outside an area of the first thermally conductive layer defined by a perimeter of the light emitting device.

58. A light emitting device assembly according to claim 57 wherein the first thermally conductive layer is electrically conductive and wherein the first thermally conductive layer comprises a substantially circular first thermally conductive layer, further comprising:

a conductive trace on the electrically insulating substrate, wherein the conductive trace extends from the substantially circular first thermally conductive layer.

59. A light emitting device assembly according to claim 57 wherein an area of the first thermally conductive layer defined within a perimeter of the light emitting device is free of all thermally conductive vias.