Light emitting diode (LED) arrays including direct die attach and related assemblies

• US 9,831,220 B2
• Filed: 03/20/2012
• Issued: 11/28/2017
• Est. Priority Date: 01/31/2011
• Status: Active Grant

• Current Assignee: Creeled Incorporated
• Original Assignee: CREE Incorporated (Wolfspeed, Inc.)
• Inventors: Donofrio, Matthew, Hussell, Christopher P., Edmond, John Adam
• Primary Examiner(s): Wright, Tucker J
• Application Number:
  US13/424,699
• Publication Number:
  US 20130193453A1
• Time in Patent Office: 2,079 Days
• 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 33/20 with a particular shape, e.g. curved or truncated substrate
• CPC Class Codes: H01L 33/505 characterised by the shape, e.g. plate or foil
• 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

An electronic device may include a packaging substrate having a packaging face, and the packaging substrate may include positive and negative electrically conductive pads on the packaging face. A plurality of light emitting diodes may be electrically and mechanically coupled to the packaging face of the packaging substrate, with the plurality of light emitting diodes being electrically coupled between the positive and negative electrically conductive pads on the packaging face. A continuous optical coating may be provided on the plurality of light emitting diodes and on the packaging face of the packaging substrate so that the plurality of light emitting diodes are between the optical coating and the packaging substrate.

Claims

1. An electronic device comprising:

a packaging substrate having a packaging face, the packaging substrate including positive and negative electrically conductive pads on the packaging face, wherein the packaging substrate comprises a thermally conductive and electrically insulating material, and wherein the packaging substrate has a backside face opposite the packaging face, the packaging substrate further comprising,

a first backside contact electrically coupled to the positive electrically conductive pad through a first electrically conductive via,

a second backside contact electrically coupled to the negative electrically conductive pad through a second electrically conductive via, and

a metal heat conducting structure on the backside face of the packaging substrate wherein the metal heat conducting structure is electrically isolated from the first and second backside contacts, and wherein the metal heat conducting structure is between the first and second backside contacts on the backside face;

a plurality of light emitting diodes electrically and mechanically coupled to the packaging face of the packaging substrate, wherein the plurality of light emitting diodes are electrically coupled between the positive and negative electrically conductive pads on the packaging face;

a continuous optical coating on the plurality of light emitting diodes and on the packaging face of the packaging substrate so that the plurality of light emitting diodes are between the optical coating and the packaging substrate, wherein the continuous optical coating comprises a layer of a transparent and/or translucent material including a phosphor material therein, wherein an optic area is defined by an area of the packaging face covered by the continuous optical coating; and

wherein each of the plurality of light emitting diodes comprises,

a diode region having first and second opposing faces including therein an n-type layer and a p-type layer,

an anode contact that ohmically contacts the p-type layer and extends on the first face,

a cathode contact that ohmically contacts the n-type layer and extends on the first face, and

a support substrate on the second face of the diode region, wherein the diode region is between the support substrate and the anode and cathode contacts, wherein the anode and cathode contacts are between the n-type layer and the packaging substrate in a direction that is orthogonal with respect to the packaging face of the packaging substrate, wherein the anode and cathode contacts are between the p-type layer and the packaging substrate in the direction that is orthogonal with respect to the packaging face of the packaging substrate, and wherein the support substrate has a thickness of at least about 50 micrometers.

2. The electronic device of claim 1 wherein the plurality of light emitting diodes are configured to generate at least 25 lumens per square millimeter of the optic area while delivering at least 100 lumens per watt of power consumed.

3. The electronic device of claim 1 wherein the plurality of light emitting diodes comprises at least 16 light emitting diodes between the continuous optical coating and the packaging substrate.

4. The electronic device of claim 3 wherein the plurality of light emitting diodes comprises at least 72 light emitting diodes.

5. The electronic device of claim 1 wherein at least one of the light emitting diodes is free of wirebonds.

6. The electronic device of claim 1 wherein for each of the light emitting diodes the anode contact is electrically and mechanically coupled to the packaging substrate using a first metallic bond physically located between the anode contact and the packaging substrate and the cathode contact is electrically and mechanically coupled to the packaging substrate using a second metallic bond physically located between the cathode contact and the packaging substrate.

7. The electronic device of claim 6 wherein a first planar interface is defined between the first backside contact and a first area of the backside face, and wherein a second planar interface is defined between the second backside contact and a second area of the backside face.

8. The electronic device of claim 7 wherein the metal heat conducting structure is aligned with the plurality of light emitting diodes in a direction perpendicular with respect to the packaging face of the packaging substrate, and wherein a third planar interface is defined between the metal heat conducting structure and a third area of the backside face of the packaging substrate.

9. The electronic device of claim 1 wherein for each of the plurality of light emitting diodes, the diode region is between the support substrate and the packaging substrate, the continuous optical coating is coated on the support substrate, and the packaging substrate is free of wirebonds electrically coupled between the packaging substrate and the light emitting diode.

10. The electronic device of claim 1 wherein a thickness of the continuous optical coating relative to the packaging face of the packaging substrate is greater than a thickness of each of the plurality of light emitting diodes relative to the packaging face of the packaging substrate, and wherein a surface of the continuous optical coating opposite the packaging substrate is substantially planar over an area including the plurality of light emitting diodes.

11. The electronic device of claim 1 wherein the optic area is in the range of about 20 square millimeters to about 200 square millimeters.

12. The electronic device of claim 1 wherein the plurality of light emitting diodes comprises a first string of light emitting diodes electrically coupled in series between the positive and negative electrically conductive pads, and a second string of light emitting diodes electrically coupled in series between the positive and negative electrically conductive pads, wherein a node between two light emitting diodes of the first string is electrically coupled to a node between two light emitting diodes of the second string, and wherein at least one of the plurality of light emitting diodes is electrically coupled to the packaging substrate using no more than one wirebond.

13. The electronic device of claim 1 wherein the layer of the transparent and/or translucent material includes multiple different phosphor materials therein, wherein each of the different phosphor materials is configured to emit a respective different wavelength of light responsive to light generated by the plurality of light emitting diodes.

14. The electronic device of claim 1 wherein the plurality of light emitting diodes are configured to generate at least 20 lumens per square millimeter of the optic area while delivering at least 100 lumens per watt of power consumed by the plurality of light emitting diodes between the continuous optical coating and the packaging substrate and while delivering at least 600 absolute lumens from the plurality of light emitting diodes between the continuous optical coating and the packaging substrate.

15. The electronic device of claim 1 wherein the plurality of light emitting diodes comprises first and second light emitting diodes between the continuous optical coating and the packaging substrate wherein the first and second light emitting diodes are spaced apart by a distance in the range of about 20 micrometers to about 500 micrometers.

16. The electronic device of claim 1 wherein a first planar interface is defined between the first backside contact and a first area of the backside face, and wherein a second planar interface is defined between the second backside contact and a second area of the backside face.

17. The electronic device of claim 16 wherein the packaging substrate comprises a thermally conductive and electrically insulating material, and wherein the metal heat conducting structure is aligned with the plurality of light emitting diodes in a direction perpendicular with respect to the packaging face of the packaging substrate, and wherein a third planar interface is defined between the metal heat conducting structure and a third area of the backside face of the packaging substrate.

18. The electronic device of claim 1 wherein a metal to non-metal interface between the anode contact and the light emitting diode is coplanar with a metal to non-metal interface between the cathode contact and the light emitting diode.

19. The electronic device of claim 1 wherein the support substrate of each of the plurality of light emitting diodes is separated from the support substrate of adjacent ones of the plurality of light emitting diodes.

20. The electronic device of claim 19 wherein the support substrate of each of the plurality of light emitting diodes is separated from the support substrate of adjacent ones of the plurality of light emitting diodes by a portion of the continuous optical coating.

21. The electronic device of claim 19 wherein a surface area of a first face of the support substrate of each of the plurality of light emitting diodes adjacent the second face of the respective diode region is greater than a surface area of a second face of the support substrate remote from the second face of the respective diode region.

22. The electronic device of claim 1 further comprising:

a dam surrounding the plurality of light emitting diodes, wherein the continuous optical coating is confined within the dam and the continuous optical coating is separate from the dam, wherein the dam comprises an interior face adjacent the plurality of light emitting diodes and an exterior face opposite the interior face that is remote from the plurality of light emitting diodes, and wherein the continuous optical coating is confined within an interior perimeter of the dam defined by the interior face.

23. The electronic device of claim 1 further comprising:

a dam surrounding the plurality of light emitting diodes, wherein the continuous optical coating is confined within the dam and the continuous optical coating is separate from the dam, and wherein an entirety of the dam is outside a perimeter surrounding the plurality of light emitting diodes.

24. The electronic device of claim 1 further comprising:

a dam surrounding the plurality of light emitting diodes, wherein the continuous optical coating is confined within the dam and the continuous optical coating is separate from the dam.

25. An electronic device comprising:

a packaging substrate having a packaging face, the packaging substrate including positive and negative electrically conductive pads on the packaging face;

a plurality of light emitting diodes electrically and mechanically coupled to the packaging face of the packaging substrate, wherein the plurality of light emitting diodes are electrically coupled between the positive and negative electrically conductive pads on the packaging face; and

a continuous optical coating on the plurality of light emitting diodes and on the packaging face of the packaging substrate so that the plurality of light emitting diodes are between the optical coating and the packaging substrate, wherein an optic area is defined by an area of the packaging face covered by the continuous optical coating,

wherein the packaging substrate has a backside face opposite the packaging face, the packaging substrate further comprising a first backside contact electrically coupled to the positive electrically conductive pad through a first electrically conductive via through the packaging substrate, and a second backside contact electrically coupled to the negative electrically conductive pad through a second electrically conductive via through the packaging substrate, and

wherein the packaging substrate comprises an aluminum nitride substrate, and a metal heat conducting structure on the backside face of the packaging substrate wherein the metal heat conducting structure is electrically isolated from the first and second backside contacts, and wherein the metal heat conducting structure is aligned with the plurality of light emitting diodes in a direction perpendicular with respect to the packaging face of the packaging substrate, wherein a first interface is defined between the first backside contact and a first area of the backside face of the packaging substrate, and wherein a second interface is defined between the second backside contact and a second area of the backside face of the packaging substrate;

wherein the metal heat conducting structure is between the first and second backside contacts on the backside face.

26. The electronic device of claim 25 wherein the first interface is a first planar interface between the first backside contact and the first area of the backside face, and wherein the second interface is a second planar interface between the second backside contact and the second area of the backside face.

27. The electronic device of claim 26 wherein a third planar interface is defined between the metal heat conducting structure and a third area of the backside face of the packaging substrate, and wherein the metal heat conducting structure is between the first and second backside contacts on the backside face.

28. The electronic device of claim 25 further comprising a dam surrounding the plurality of light emitting diodes, wherein the dam comprises an interior face adjacent the plurality of light emitting diodes and an exterior face opposite the interior face that is remote from the plurality of light emitting diodes, and wherein the continuous optical coating is confined within an interior perimeter of the dam defined by the interior face.

29. The electronic device of claim 25 wherein the heat conducting structure is non-overlapping with respect to the first and second backside contacts on the backside face.

30. The electronic device of claim 29 wherein a third interface is defined between the heat conducting structure and a third area of the backside face, and wherein the first, second, and third interfaces are co-planar.

31. An electronic device comprising:

a packaging substrate having a packaging face, the packaging substrate including positive and negative electrically conductive pads on the packaging face, wherein the packaging substrate comprises a thermally conductive and electrically insulating material, and wherein the packaging substrate has a backside face opposite the packaging face, the packaging substrate further comprising,

a first backside contact electrically coupled to the positive electrically conductive pad through a first electrically conductive via,

a second backside contact electrically coupled to the negative electrically conductive pad through a second electrically conductive via, and

a metal heat conducting structure on the backside face of the packaging substrate wherein the metal heat conducting structure is electrically isolated from the first and second backside contacts, and wherein the metal heat conducting structure is between the first and second backside contacts on the backside face;

a plurality of light emitting diodes electrically and mechanically coupled to the packaging face of the packaging substrate, wherein the plurality of light emitting diodes are electrically coupled between the positive and negative electrically conductive pads on the packaging face; and

a continuous optical coating on the plurality of light emitting diodes and on the packaging face of the packaging substrate so that the plurality of light emitting diodes are between the optical coating and the packaging substrate, wherein the continuous optical coating comprises a layer of a transparent and/or translucent material including a phosphor material therein, wherein a thickness of the continuous optical coating relative to the packaging face of the packaging substrate is greater than a thickness of each of the plurality of light emitting diodes relative to the packaging face of the packaging substrate, wherein a surface of the continuous optical coating opposite the packaging substrate is substantially planar over an area including the plurality of light emitting diodes, and wherein at least one of the plurality of light emitting diodes is free of wirebonds; and

wherein at least one of the light emitting diodes comprises an anode contact electrically and mechanically coupled to the packaging substrate using a first metallic bond located between the anode contact and the packaging substrate and a cathode contact electrically and mechanically coupled to the packaging substrate using a second metallic bond located between the cathode contact and the packaging substrate, wherein a metal to non-metal interface between the anode contact and the light emitting diode is coplanar with a metal to non-metal interface between the cathode contact and the light emitting diode.

32. The electronic device of claim 31 wherein an optic area is defined by an area of the packaging face covered by the continuous optical coating, and wherein the plurality of light emitting diodes are configured to generate at least 20 lumens per square millimeter of the optic area while delivering at least 100 lumens per watt of power consumed by the plurality of light emitting diodes between the continuous optical coating and the packaging substrate.

33. The electronic device of claim 31 wherein the plurality of light emitting diodes comprises at least 16 light emitting diodes between the continuous optical coating and the packaging substrate.

34. The electronic device of claim 33 wherein the plurality of light emitting diodes comprises at least 72 light emitting diodes.

35. The electronic device of claim 31 wherein a first planar interface is defined between the first backside contact and a first area of the backside face, and wherein a second planar interface is defined between the second backside contact and a second area of the backside face.

36. The electronic device of claim 35 wherein the metal heat conducting structure is aligned with the plurality of light emitting diodes in a direction perpendicular with respect to the packaging face of the packaging substrate, and wherein a third planar interface is defined between the metal heat conducting structure and a third area of the backside face of the packaging substrate.

37. The electronic device of claim 31 wherein the plurality of light emitting diodes comprises a first string of light emitting diodes electrically coupled in series between the positive and negative electrically conductive pads, and a second string of light emitting diodes electrically coupled in series between the positive and negative electrically conductive pads, wherein a node between two light emitting diodes of the first string is electrically coupled to a node between two light emitting diodes of the second string, and wherein at least one of the plurality of light emitting diodes is free of wirebonds.

38. The electronic device of claim 31 wherein the layer of the transparent and/or translucent material includes multiple different phosphor materials therein, wherein each of the different phosphor materials is configured to emit a respective different wavelength of light responsive to light generated by the plurality of light emitting diodes.

39. The electronic device of claim 31 further comprising:

a dam surrounding the plurality of light emitting diodes, wherein the continuous optical coating is confined within the dam and the continuous optical coating is separate from the dam, wherein the dam comprises an interior face adjacent the plurality of light emitting diodes and an exterior face opposite the interior face that is remote from the plurality of light emitting diodes, and wherein the continuous optical coating is confined within an interior perimeter of the dam defined by the interior face.

40. The electronic device of claim 31 further comprising:

a dam surrounding the plurality of light emitting diodes, wherein the continuous optical coating is confined within the dam and the continuous optical coating is separate from the dam, and wherein an entirety of the dam is outside a perimeter surrounding the plurality of light emitting diodes.

41. The electronic device of claim 31 further comprising:

a dam surrounding the plurality of light emitting diodes, wherein the continuous optical coating is confined within the dam, and the continuous optical coating is separate from the dam.

42. An electronic device comprising:

a packaging substrate having a packaging face, the packaging substrate including positive and negative electrically conductive pads on the packaging face, wherein the packaging substrate comprises a thermally conductive and electrically insulting material, and wherein the packaging substrate has a backside face opposite the packaging face, the packaging substrate further comprising,

a first backside contact electrically coupled to the positive electrically conductive pad through a first electrically conductive via,

a second backside contact electrically coupled to the negative electrically conductive pad through a second electrically conductive via, and

a metal heat conducting structure on the backside face of the packaging substrate wherein the metal heat conductive structure is electrically isolated from the first and second backside contacts, and wherein the metal heat conducting structure is between the first and second backside contacts on the backside face;

a plurality of light emitting diodes electrically and mechanically coupled to the packaging face of the packaging substrate, wherein the plurality of light emitting diodes are electrically coupled between the positive and negative electrically conductive pads on the packaging face, wherein each of the plurality of light emitting diodes comprises,

a diode region having first and second opposing faces including therein an n-type layer and a p-type layer,

an anode contact that ohmically contacts the p-type layer and extends on the first face,

a cathode contact that ohmically contacts the n-type layer and extends on the first face, and

a support substrate on the second face of the diode region, wherein the diode region is between the support substrate and the anode and cathode contacts, wherein the anode and cathode contacts are between the n-type layer and the packaging substrate in a direction that is orthogonal with respect to the packaging face of the packaging substrate, wherein the anode and cathode contacts are between the p-type layer and the packaging substrate in a direction that is orthogonal with respect to the packaging face of the packaging substrate, and wherein the support substrate has a thickness of at least about 50 micrometers; and

a continuous optical coating on the plurality of light emitting diodes and on the packaging face of the packaging substrate so that the plurality of light emitting diodes are between the optical coating and the packaging substrate, wherein the continuous optical coating comprises a layer of a transparent and/or translucent material including a phosphor material therein, wherein a thickness of the continuous optical coating relative to the packaging face of the packaging substrate is greater than a thickness of each of the plurality of light emitting diodes relative to the packaging face of the packaging substrate, wherein a surface of the continuous optical coating opposite the packaging substrate is substantially planar over an area including the plurality of light emitting diodes, and wherein at least one of the plurality of light emitting diodes is free of wirebonds.

43. The electronic device of claim 42 wherein for each of the plurality of light emitting diodes, the diode region is between the support substrate and the packaging substrate, the continuous optical coating is coated on the support substrate, and the packaging substrate is free of wirebonds electrically coupled between the packaging substrate and the light emitting diode.

44. The electronic device of claim 42 wherein a first planar interface is defined between the first backside contact and a first area of the backside face, and wherein a second planar interface is defined between the second backside contact and a second area of the backside face.

45. The electronic device of claim 44 wherein the metal heat conducting structure is aligned with the plurality of light emitting diodes in a direction perpendicular with respect to the packaging face of the packaging substrate, and wherein a third planar interface is defined between the metal heat conducting structure and a third area of the backside face of the packaging substrate.

46. The electronic device of claim 42 wherein a metal to non-metal interface between the anode contact and the light emitting diode is coplanar with a metal to non-metal interface between the cathode contact and the light emitting diode.

47. The electronic device of claim 42 wherein the support substrate of each of the plurality of light emitting diodes is separated from the support substrate of adjacent ones of the plurality of light emitting diodes.

48. The electronic device of claim 47 wherein the support substrate of each of the plurality of light emitting diodes is separated from the support substrate of adjacent ones of the plurality of light emitting diodes by a portion of the continuous optical coating.

49. The electronic device of claim 47 wherein a surface area of a first face of the support substrate of each of the plurality of light emitting diodes adjacent the second face of the respective diode region is greater than a surface area of a second face of the support substrate remote from the second face of the respective diode region.

50. The electronic device of claim 42 further comprising:

a dam surrounding the plurality of light emitting diodes, wherein the continuous optical coating is confined within the dam and the continuous optical coating is separate from the dam, wherein the dam comprises an interior face adjacent the plurality of light emitting diodes and an exterior face opposite the interior face that is remote from the plurality of light emitting diodes, and wherein the continuous optical coating is confined within an interior perimeter of the dam defined by the interior face.

51. The electronic device of claim 42 further comprising:

a dam surrounding the plurality of light emitting diodes, wherein the continuous optical coating is confined within the dam and the continuous optical coating is separate from the dam, and wherein an entirety of the dam is outside a perimeter surrounding the plurality of light emitting diodes.

52. The electronic device of claim 42 further comprising:

a dam surrounding the plurality of light emitting diodes, wherein the continuous optical coating is confined within the dam and the continuous optical coating is separate from the dam.