Multi-die LED package

• US 9,082,921 B2
• Filed: 04/06/2012
• Issued: 07/14/2015
• Est. Priority Date: 10/31/2007
• Status: Active Grant

• Current Assignee: Creeled Incorporated
• Original Assignee: CREE Incorporated (Wolfspeed, Inc.)
• Inventors: Wilcox, Kurt S., Keller, Bernd P., Lowes, Theodore, Andrews, Peter Scott
• Primary Examiner(s): ZARNEKE, DAVID A
• Application Number:
  US13/441,620
• Publication Number:
  US 20130092960A1
• Time in Patent Office: 1,194 Days
• Field of Search: 257/99
• US Class Current: 1/1
• 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 2224/48137 the bodies being arranged next to each other, e.g. on a common substrate
• CPC Class Codes: H01L 2224/48227 connecting the wire to a bond pad of the item
• CPC Class Codes: H01L 2224/49113 the connectors connecting different bonding areas on the semiconductor or solid-state body to a common bonding area outside the body, e.g. converging wires
• CPC Class Codes: H01L 2224/73265 Layer and wire connectors
• CPC Class Codes: H01L 24/73 Means for bonding being of different types provided for in two or more of groups H01L24/10, H01L24/18, H01L24/26, H01L24/34, H01L24/42, H01L24/50, H01L24/63, H01L24/71
• CPC Class Codes: H01L 25/0753 the devices being arranged next to each other
• 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 2924/01087 Francium [Fr]
• CPC Class Codes: H01L 31/12 structurally associated with, e.g. formed in or on a common substrate with, one or more electric light sources, e.g. electroluminescent light sources, and electrically or optically coupled thereto semiconductor devices with at least one potential barrier or surface barrier adapted for light emission H01L33/00; amplifiers using electroluminescent element and photocell H03F17/00; electroluminescent light sources per se H05B33/00
• CPC Class Codes: H01L 33/08 with a plurality of light emitting regions, e.g. laterally discontinuous light emitting layer or photoluminescent region integrated within the semiconductor body H01L27/15 takes precedence
• CPC Class Codes: H01L 33/405 Reflective materials
• CPC Class Codes: H01L 33/48 characterised by the semiconductor body packages
• CPC Class Codes: H01L 33/486 adapted for surface mounting
• CPC Class Codes: H01L 33/54 having a particular shape
• 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

Abstract

A light-emitting device comprising (a) a submount having front and back sides and including a ceramic layer; (b) an array of light-emitting diodes (LEDs) on the front side; and (c) a lens overmolded on the submount and covering the LED array. In some embodiments, the submount comprises at least two electrically-conductive contact pads on the front side, and each LED in the array is secured with respect to one of the contact pads.

Claims

1. A light-emitting device comprising:

a submount having front and back sides and including a ceramic layer;

an array of light emitting diodes (LEDs) on the front side; and

an asymmetric lens overmolded on the submount and covering the LED array;

wherein;

the submount comprises at least three contact pads, including a positive contact pad, a negative contact pad, and at least one intermediate contact pad;

a first subset of the LEDs is secured with respect to one of the positive and negative contact pads; and

a second subset of the LEDs is secured with respect to one of the at least one intermediate contact pads, the first and second subsets being mutually-exclusive and having the same number of LEDs.

2. The device of claim 1 wherein the ceramic material comprises aluminum nitride.

3. The device of claim 1 wherein the contact pads each comprise metallization with copper.

4. The device of claim 3 wherein the copper metallization has a thickness of about 40-60 microns.

5. The device of claim 4 wherein the copper metallization has a thickness of about 50 microns.

6. The device of claim 3 wherein the contact pads each has an outer layer of silver.

7. The device of claim 6 wherein the outer layer has a thickness of about 0.2-0.5 microns.

8. The device of claim 6 wherein the contact pads each has an inner layer of titanium between the copper and the ceramic.

9. The device of claim 8 wherein the inner layer has a thickness of about 0.6 microns.

10. The device of claim 1 wherein the array includes eight LEDs.

11. The device of claim 1 wherein the array includes forty-eight LEDs.

12. The device of claim 1 wherein there is one intermediate contact pad and each LED of the array is in one of the two subsets.

13. The device of claim 12 wherein the array includes eight LEDs.

14. The device of claim 12 wherein the array includes forty-eight LEDs.

15. The device of claim 1 wherein each LED has a pad side and an opposite side and each LED is electrically connected to an adjacent contact pad with at least one wirebonded conductor.

16. The device of claim 15 wherein each LED is electrically connected with two wirebonded conductors for electrical redundancy.

17. The device of claim 1 configured to refract LED-emitted light toward a preferential direction.

18. The device of claim 17 wherein:

the LED array defines an emitter axis; and

the lens has an outer surface and a centerline which is offset from the emitter axis toward the preferential direction.

19. The device of claim 17 wherein the lens is shaped for refraction of LED-emitted light toward the preferential direction.

20. The device of claim 19 wherein:

the LED array defines an emitter axis; and

the lens has an outer surface and a centerline which is offset from the emitter axis toward the preferential direction.

21. The device of claim 1 further including at least two electrically-conductive mount pads on the back side for electrical connection of the device.

22. The device of claim 21 wherein the submount has electrically-conductive vias providing electrical connection between the mount pads and the contact pads.

23. The device of claim 1 wherein the array defines an LED-populated area on the submount and the LED-populated area has an aspect ratio greater than 1.

24. The LED light source of claim 23 wherein the aspect ratio is at least about 2.

25. The LED light source of claim 24 wherein the aspect ratio is at least about 3.

26. The LED light source of claim 23 wherein the LED-populated area is rectangular.

27. The LED light source of claim 1 wherein the array includes at least eight LEDs positioned in two rows of four LEDs in each row.

28. The LED light source of claim 1 wherein the array includes forty-eight LEDs positioned in four rows of twelve LEDs in each row.

29. A light-emitting device comprising:

a submount having front and back sides, an electrically-insulating layer, at least three front-side electrically-conductive contact pads including a positive contact pad, a negative contact pad, and at least one intermediate contact pad; and

an array of light emitting diodes (LEDs) on the front side, the array including a first subset of the LEDs secured with respect to one of the positive and negative contact pads, and a second subset of the LEDs secured with respect to one of the at least one intermediate contact pads, the first and second subsets being mutually-exclusive and having the same number of LEDs.

30. The device of claim 29 wherein the array includes eight LEDs.

31. The device of claim 29 wherein the array includes forty-eight LEDs.

32. The device of claim 29 wherein there is one intermediate contact pad and each LED of the array is in one of the two subsets.

33. The device of claim 32 wherein the array includes eight LEDs.

34. The device of claim 32 wherein the array includes forty-eight LEDs.

35. The device of claim 29 wherein each LED has a pad side and an opposite side and each LED is electrically connected to an adjacent contact pad with at least one wirebonded conductor.

36. The device of claim 35 wherein each LED is electrically connected with two wirebonded conductors for electrical redundancy.

37. The device of claim 29 wherein there are two intermediate contact pads and further including a third mutually-exclusive subset of LEDs of the array, and each of the LEDs is in one of the three subsets.

38. The device of claim 37 wherein the array defines an LED-populated area on the submount and the LED-populated area is rectangular.

39. The device of claim 29 wherein:

one of the positive and negative contact pads is an innermost pad and is adjacent to a first edge of the submount;

a first intermediate contact pad substantially surrounds the innermost pad on three sides thereof other than the first-edge-adjacent side thereof; and

the other of the positive and negative contact pads substantially surrounds the first intermediate contact pad on three sides thereof other than the first-edge-adjacent side thereof.

40. The device of claim 39 wherein the array defines an LED-populated area on the submount and the LED-populated area is rectangular having a smaller dimension adjacent to the first edge of the submount.

41. The device of claim 39 wherein the innermost pad is the positive contact pad.

42. The device of claim 41 wherein:

the array defines an LED-populated area on the submount and the LED-populated area is rectangular having a smaller dimension adjacent to the first edge of the submount;

the first subset of the LEDs is on the innermost pad; and

the second subset of the LEDs is on the intermediate contact pad.

43. The device of claim 39 further including:

a second intermediate contact pad which substantially surrounds the first intermediate contact pad on three sides thereof other than the first-edge-adjacent side thereof; and

a third subset of the LEDs, the first, second and third subsets being mutually-exclusive and having the same number of LEDs.

44. The device of claim 43 wherein the innermost pad is the positive contact pad.

45. The device of claim 44 wherein:

the array defines an LED-populated area on the submount and the LED-populated area is rectangular having a smaller dimension adjacent to the first edge of the submount;

the first subset of the LEDs is on the innermost pad;

the second subset of the LEDs is on the first intermediate contact pad; and

the third subset of the LEDs is on the second intermediate contact pad.

46. The device of claim 29 wherein:

one of the positive and negative contact pads is an innermost pad;

a first intermediate contact pad substantially surrounds the innermost pad on at least three sides thereof; and

the other of the positive and negative contact pads substantially surrounds the first intermediate contact pad on at least three sides thereof.

47. The device of claim 46 wherein the array defines an LED-populated area on the submount having an aspect ratio of greater than 1.

48. The device of claim 46 wherein the LED-populated area is rectangular.

49. The device of claim 47 wherein the array defines an LED-populated area on the submount having an aspect ratio of at least about 2.

50. The device of claim 49 wherein the array defines an LED-populated area on the submount having an aspect ratio of at least about 3.

51. A light-emitting device comprising:

a submount having an electrically-insulating layer, a front side, and at least three front-side electrically-conductive contact pads, including a positive contact pad, a negative contact pad, and at least one intermediate contact pad; and

an array of light emitting diodes (LEDs) on the front side, the array defining an LED-populated area having an aspect ratio greater than 1, the array including first and second mutually-exclusive subsets of the LEDs, the LEDs of each of the subsets being electrically in parallel with each other and the subsets being electrically in series;

wherein the LEDs of the first subset are on the positive contact pad and the LEDs of the second subset are on the intermediate contact pad.

52. A light-emitting device comprising:

a submount; and

a rectangular light emitting diode (LED) array defining an LED-populated area having an aspect ratio greater than 1, the LED array including first and second subsets of the LEDs, the LEDs within each of the subsets being electrically in parallel with each other and the first and second subsets being electrically in series with each other.

53. The light-emitting device of claim 52 further comprising at least three electrically-conductive contact pads, including a positive contact pad, a negative contact pad, and at least one intermediate contact pad.

54. The light-emitting device of claim 53 wherein the first subset of the LEDs is secured with respect to one of the positive and negative contact pads, and the second subset of the LEDs is secured with respect to one of the at least one intermediate contact pads.

55. The light-emitting device of claim 54 further comprising a lens on the submount and covering the LED array.

56. The light-emitting device of claim 55 wherein the lens is overmolded on the submount.

57. The light-emitting device of claim 56 wherein the lens is asymmetric.

58. The light-emitting device of claim 52 further comprising a lens on the submount and covering the LED array.

59. The light-emitting device of claim 58 wherein the lens is overmolded on the submount.

60. The light-emitting device of claim 59 wherein the lens is asymmetric.

61. A submount comprising first, second and third contact pads, the second contact pad substantially surrounding the first contact pad on at least three sides, and the third contact pad substantially surrounding the second contact pad on at least three sides.

62. The submount of claim 61 wherein the first contact pad is a positive contact pad, the second contact pad is an intermediate contact pad, and the third contact pad is a negative contact pad.

63. A light-emitting device comprising:

a submount including first, second and third contact pads, the second contact pad substantially surrounding the first contact pad on at least three sides, and the third contact pad substantially surrounding the second contact pad on at least three sides; and

a light emitting diode (LED) array on the contact pads.

64. The light-emitting device of claim 63 wherein the first contact pad is a positive contact pad, the second contact pad is an intermediate contact pad, and the third contact pad is a negative contact pad.