LED array and method for fabricating same

• US 10,295,147 B2
• Filed: 10/31/2007
• Issued: 05/21/2019
• Est. Priority Date: 11/09/2006
• Status: Active Grant

• Current Assignee: Creeled Incorporated
• Original Assignee: CREE Incorporated (Wolfspeed, Inc.)
• Inventors: Yuan, Thomas Cheng-Hsin, Keller, Bernd
• Primary Examiner(s): Sawhney, Hargobind S
• Application Number:
  US11/982,276
• Publication Number:
  US 20080170396A1
• Time in Patent Office: 4,220 Days
• Field of Search: 257 88, 257 83, 257E2103, 257E2301, 257E2502, 257 25032, 257 79, 257 91-100, 257465, 257601, 362800, 362368, 362373, 362227, 362236, 362252, 362640, 362647, 362657-659, 362235, 362238, 36224901, 36224902, 36224914, 362294, 362308, 362545, 362547, 345 11, 345 13
• CPC Class Codes: F21K 9/00 Light sources using semiconductor devices as light-generating elements, e.g. using light-emitting diodes [LED] or lasers
• CPC Class Codes: F21S 2/005 of modular construction
• CPC Class Codes: F21V 5/007 Array of lenses or refractors for a cluster of light sources, e.g. for arrangement of multiple light sources in one plane combination of two or more refractors F21V5/008
• CPC Class Codes: F21V 5/04 of lens shape
• CPC Class Codes: F21V 5/10 comprising photoluminescent material
• CPC Class Codes: F21Y 2105/10 comprising a two-dimensional array of point-like light-generating elements
• CPC Class Codes: F21Y 2107/40 on the sides of polyhedrons, e.g. cubes or pyramids
• CPC Class Codes: F21Y 2113/00 Combination of light sources
• CPC Class Codes: F21Y 2115/10 Light-emitting diodes [LED]
• 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 33/62 Arrangements for conducting electric current to or from the semiconductor body, e.g. lead-frames, wire-bonds or solder balls

Abstract

A light emitting device or array comprising a submount having a top surface, a bottom surface and a plurality of edges, with input and output terminals disposed on the top surface. A plurality of attach pads and traces are also disposed on the top surface and electrically connected between the input and output terminals. A plurality of LEDs are also included, each of which is mounted to one of the attach pads. The attach pads cover more of the top surface than the LEDs and spread heat from the LEDs to the top surface of the submount. A plurality of lenses are also included each of which is molded over a respective one of the attach pads and covers the LED mounted to the particular attach pad. The arrays are shaped and arranged so that they can be easily attached to similar arrays in a tiling fashion, with the desired number of arrays included to meet the desired lighting requirements. Methods for fabricating the arrays from a single submount or submounts panel are also disclosed.

Claims

1. An emitter array, comprising:

a submount comprising at least one of a PCB, a FR-4 PCB, or a metal core PCB, said submount further comprising a top surface, a plurality of edges, and conductive features;

said conductive features comprising input and output terminals, a plurality of attach pads, and a plurality of electrical traces distinct from said input and output terminals, wherein at least some of said conductive features are on a portion of said top surface of said submount;

said input and output terminals on said top surface of said submount, wherein each of said input and output terminals extend continuously proximate to and along more than one edge of said plurality of edges, providing access to said terminals from more than one edge of said plurality of edges;

a plurality of solid state emitters, at least one of said solid state emitters flip-chip bonded to at least one attach pad on said submount top surface, said attach pads covering more of said submount top surface than said solid state emitters and configured to conduct heat from said one of said plurality of solid state emitters to the top surface of said submount, wherein said submount is configured to conduct heat from said top surface through said submount;

said plurality of electrical traces on said top surface of said submount configured to connect said plurality of solid state emitters with said input and output terminals, such that an electrical path from said input terminal to said output terminal through said plurality of solid state emitters is on or above said top surface; and

a plurality of lenses, each lens in the plurality of lenses over a respective one of said attach pads and covering said at least one of said solid state emitters attached to said respective one of said attach pads, wherein said plurality of lenses are on said top surface of said, wherein said emitter array further comprises secondary optics over at least some of said plurality of lenses, said secondary optics integrated into a single assembly submount.

2. The array of claim 1, wherein said solid state emitters comprise light emitting diodes (LEDs).

3. The array of claim 2, wherein said attach pads extend radially on said top surface of said submount from an edge of at least one of said plurality of solid state emitters.

4. The array of claim 1, wherein said attach pads extend on said top surface of said submount from an edge of at least one of said plurality of solid state emitters.

5. The array of claim 1, wherein said substrate is polygonal.

6. The array of claim 1, said input terminal further comprising a first set of contact pads proximate to a corresponding plurality of said edges.

7. The array of claim 6, wherein said input and output terminals further comprise a second set of contact pads proximate to a corresponding plurality of said edges opposite said first set of contact pads.

8. The array of claim 1, wherein said electrical traces connect said solid state emitters and said attach pads in series between said input and output terminals.

9. The array of claim 1, further comprising a heat spreader on a bottom surface of said submount.

10. The array of claim 1, wherein each of said attach pads in said plurality of attach pads is adjacent to at least one of said plurality of traces.

11. The array of claim 1, wherein at least one pair of said attach pads in said plurality of attach pads is connected by one of said plurality of traces.

12. The array of claim 1, wherein said input terminal is coupled to a first trace of said plurality of traces, said first trace coupled to a first attach pad of said plurality of attach pads.

13. The array of claim 1, wherein said output terminal is coupled to a second trace of said plurality of traces, said second trace coupled to a second attach pad of said plurality of attach pads.

14. The array of claim 1, wherein the electrical path is entirely on or above said top surface of said submount.

15. The emitter array of claim 1, further comprising secondary optics over at least some of said plurality of lenses.

16. The emitter array of claim 15, wherein said secondary optics are dome-shaped.

17. The emitter array of claim 15, wherein said secondary optics are integrated into a single assembly.

18. The emitter array of claim 1, wherein said plurality of lenses are dome-shaped.

19. A light emitting diode (LED) array, comprising:

a submount comprising at least one of a PCB, a FR-4 PCB, or a metal core PCB, said submount further comprising a top surface, a bottom surface, at least six edges, and conductive features;

said conductive features comprising input and output terminals, a plurality of thermally conductive elements, and a plurality of electrical traces distinct from said input and output terminals, wherein at least some of said conductive features are on a portion of said top surface of said submount;

said input and output terminals on said top surface, said input terminal proximate to, but set back from, at least first, second, and third edges of said submount, and said output terminal proximate to, but set back from, at least fourth, fifth, and sixth edges of said submount, wherein each of said first, second, and third edges is opposite one of said fourth, fifth, and sixth edges;

said plurality of thermally conductive elements on said top surface, said plurality of thermally conductive elements comprising a plurality of attach pads; and

a plurality of LEDs, each LED mounted on one of said attach pads on said submount top surface, said attach pads covering more of said submount top surface than said plurality of LEDs, an electrical signal applied to said input and output terminals causing said plurality of LEDs to emit light, at least some of said thermally conductive elements configured to conduct heat from said plurality of LEDs top surface of said submount, wherein said submount is configured to conduct heat from said top surface through said submount;

wherein said plurality of LEDs are configured such that an electrical path from said input terminal to said output terminal is conveyed via said electrical traces through said plurality of LEDs, said electrical traces being on or above said top surface of said submount; and

a plurality of lenses, each lens in the plurality of lenses over a respective one of said attach pads and covering said at least one of said LEDs attached to said respective one of said attach pads, wherein said plurality of lenses are on said top surface of said wherein said LED array further comprises secondary optics over at least some of said plurality of lenses submount.

20. The array of claim 19, wherein said submount is hexagonal.

21. The array of claim 19, wherein said conductive elements comprise:

a plurality of traces on or above said top surface of said submount;

wherein each LED is attached to one attach pad of the plurality of attach pads, and wherein each attach pad of said plurality of attach pads is connected with at least one of said traces.

22. The array of claim 21, wherein each attach pad of said plurality of attach pads is adjacent to at least one of said plurality of traces.

23. The array of claim 21, wherein at least one pair of attach pads of said plurality of attach pads is connected by one of said plurality of traces.

24. The array of claim 21, wherein said input terminal is coupled to a first trace of said plurality of traces, said first trace coupled to a first attach pad of said plurality of attach pads.

25. The array of claim 21, wherein said output terminal is coupled to a second trace of said plurality of traces, said second trace coupled to a second attach pad of said plurality of attach pads.

26. The array of claim 19, further comprising a heat spreader on said submount.

27. The array of claim 19, further comprising secondary optics over at least some of said plurality of lenses.

28. A lamp, comprising:

a lamp body comprising an opening; and

a light source within said body to radiate light through said opening, said light source comprising at least one array, each said array comprising;

a submount comprising at least one of a PCB, a FR-4 PCB, or a metal core PCB, said submount further comprising a top surface, at least six edges, and conductive features;

said conductive features comprising input and output terminals, a plurality of conductive elements, and a plurality of electrical traces distinct from said input and output terminals, wherein at least some of said conductive features are on a portion of said top surface of said submount;

said input and output terminals on a top surface of said submount, said terminals electrically connected to a network, said input terminal along and accessible from at least first, second, and third edges of said submount, and said output terminal along and accessible from at least fourth, fifth, and sixth edges of said submount, wherein each of said first, second, and third edges is opposite one of said fourth, fifth, and sixth edges of said submount;

said plurality of conductive elements comprising a plurality of attach pads; and

a plurality of LEDs at least one of which is attached to at least one attach pad, said conductive elements configured to transfer heat from said LEDs to said top surface of said submount, wherein said attach pads cover more of said submount than said LEDs, wherein said submount is configured to conduct heat from said top surface through said submount;

wherein said plurality of conductive elements are configured such that an electrical path from said input terminal to said output terminal travels through said plurality of LEDs via said electrical traces, said electrical traces being on or above said top surface of said submount; and

a plurality of lenses, each lens in the plurality of lenses over a respective one of said attach pads and covering said at least one of said LEDs attached to said respective one of said attach pads, wherein said plurality of lenses are on said top surface of said wherein said lamp further comprises secondary optics over at least some of said plurality of lenses submount.

29. The lamp of claim 28, wherein said at least one array comprises a plurality of arrays in an expandable tiling on a surface within said body and further comprising a network of conductors connected to provide power to said arrays.

30. The lamp of claim 29, wherein said surface is thermally conductively coupled to a heat sink.

31. The lamp of claim 28, wherein each LED is attached to one of the plurality of attach pads, and wherein each attach pad of said plurality of attach pads is directly connected with at least one of said plurality of traces.

32. The lamp of claim 31, wherein each attach pad of said plurality of attach pads is adjacent to at least one of said plurality of traces.

33. The lamp of claim 31, wherein at least one pair of attach pads in said plurality of attach pads is directly connected by one of said plurality of traces.

34. The lamp of claim 31, wherein said input terminal is coupled to a first trace of said plurality of traces, said first trace coupled to a first attach pad of said plurality of attach pads.

35. The lamp of claim 31, wherein said output terminal is coupled to a second trace of said plurality of traces, said second trace coupled to a second attach pad of said plurality of attach pads.

36. The lamp of claim 28, further comprising secondary optics over at least some of said plurality of lenses.

37. A method for fabricating an emitter array, comprising:

forming conductive features on a surface of a submount, said conductive features comprising attach pads and input and output terminals, each of said input and output terminals extending continuously proximate to and along more than one side of said submount, and a plurality of electrical traces narrower than said attach pads and distinct from said input and output terminals;

providing access to said input and output terminals from more than one side of said submount;

attaching by mounting a plurality of LEDs to said attach pads such that said plurality of LEDs are electrically connected by said plurality of conductive features through said electrical traces, said plurality of conductive features configured to spread heat from said plurality of LEDs into at least a portion of said submount, wherein said attach pads cover more of said surface of said submount than said LEDs;

providing a plurality of lenses, each lens in the plurality of lenses over a respective one of said attach pads and covering said at least one of said LEDs attached to said respective one of said attach pads, wherein said plurality of lenses are on said surface of said; and

mounting secondary optics over said plurality of lenses submount.

38. The method of claim 37 further comprising depositing a solder mask partially over said conductive features.

39. The method of claim 37, wherein said forming said sets of conductive features comprises forming a plurality of traces on or above said top surface of said submount and wherein each of said attach pads is connected with at least one of said traces.

40. The method of claim 39, wherein each of said attach pads is adjacent to at least one of said plurality of traces.

41. The method of claim 39, wherein at least one pair of said attach pads is directly connected by one of said plurality of traces.

42. The method of claim 39, further comprising:

forming an input terminal on or above said submount wherein said plurality of traces comprises a first trace coupled to said input terminal, said first trace coupled to a first attach pad of said plurality of attach pads.

43. The method of claim 39, further comprising:

forming an output terminal on or above said submount, wherein said plurality of traces comprises a second trace coupled to said output terminal, said second trace coupled to a second attach pad of said plurality of attach pads.

44. The method of claim 37, further comprising disposing a heat spreader on said submount.

45. The method of claim 37, further comprising mounting secondary optics over said plurality of lenses.

46. A method for fabricating a plurality of arrays, comprising:

forming sets of attach pads and contact pads and electrical traces on a submount panel sized to accommodate a plurality of arrays, said electrical traces narrower than said attach pads and distinct from said contact pads, with each of said sets corresponding to one array in said plurality of arrays, each of said contact pads extending continuously proximate to, but set back from, more than one side of said submount panel, providing access to said contact pads from more than one side of said submount panel, said traces on or above a top surface of said submount panel;

attaching by mounting a plurality of LEDs to said submount panel such that an electrical path runs through said LEDs via said electrical traces, said electrical traces being on or above the top surface of said submount, at least one LED of said plurality of LEDs attached to one attach pad of said attach pads, said attach pads covering more of said submount panel than said LEDs and conducting heat from said plurality of LEDs to said submount;

providing a plurality of lenses, each lens in the plurality of lenses over a respective one of said attach pads and covering said at least one of said LEDs attached to said respective one of said attach pads, wherein said plurality of lenses are on said top surface of said submount panel; and

singulating said submount panel to separate it into a plurality of arrays each of which comprises a plurality of LED electrically connected so that a signal applied to one of said contact pads is conducted to illuminate the LEDs on the particular array.

47. The method of claim 46, wherein each of said attach pads is adjacent to at least one of said plurality of traces.

48. The method of claim 46, wherein at least one pair of said attach pads is directly connected by one of said plurality of traces.

49. The method of claim 46, further comprising:

forming an input terminal on or above said submount, wherein said plurality of traces comprises a first trace coupled to said input terminal, said first trace coupled to a first attach pad of said plurality of attach pads.

50. The method of claim 46, further comprising:

forming an output terminal on or above said submount, wherein said plurality of traces comprises a second trace coupled to said output terminal, said second trace coupled to a second attach pad of said plurality of attach pads.

51. The method of claim 46 wherein said electrical path is entirely on or above said top surface of said submount.

52. The method of claim 46, further comprising disposing a heat spreader on said submount.