LIGHT EMITTING DIODE (LED) ARRAYS INCLUDING DIRECT DIE ATTACH AND RELATED ASSEMBLIES

• US 20120193649A1
• Filed: 02/14/2011
• Published: 08/02/2012
• Est. Priority Date: 01/31/2011
• Status: Active Grant

• Current Assignee: Creeled Incorporated
• Original Assignee: CREE Incorporated (Wolfspeed, Inc.)
• Inventors: Donofrio, Matthew, Edmond, John Adam, Kong, Hua-Shuang, Andrews, Peter S., Emerson, David Todd
• Granted Patent: US 9,754,926 B2
• Time in Patent Office: Days
• US Class Current: 257/88
• CPC Class Codes: H01L 2224/16 of an individual bump connector
• CPC Class Codes: H01L 25/0753 the devices being arranged next to each other
• 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 substrate face with a plurality of electrically conductive pads on the packaging substrate face. A first light emitting diode die may bridge first and second ones of the electrically conductive pads. More particularly, the first light emitting diode die may include first anode and cathode contacts respectively coupled to the first and second electrically conductive pads using metallic bonds. Moreover, widths of the metallic bonds between the first anode contact and the first pad and between the first cathode contact and the second pad may be at least 60 percent of a width of the first light emitting diode die. A second light emitting diode die may bridge third and fourth ones of the electrically conductive pads. The second light emitting diode die may include second anode and cathode contacts respectively coupled to the third and fourth electrically conductive pads using metallic bonds. Widths of the metallic bonds between the second anode contact and the second pad and between the second cathode contact and the third pad may be at least 60 percent of a width of the first light emitting diode die.

Claims

1. An electronic device comprising:

a packaging substrate having a packaging substrate face, the packaging substrate comprising a plurality of electrically conductive pads on the packaging substrate face;

a first light emitting diode die bridging first and second ones of the electrically conductive pads, the first light emitting diode die including first anode and cathode contacts respectively coupled to the first and second electrically conductive pads using metallic bonds, wherein widths of the metallic bonds between the first anode contact and the first pad and between the first cathode contact and the second pad are at least 60 percent of a width of the first light emitting diode die; and

a second light emitting diode die bridging third and fourth ones of the electrically conductive pads, the second light emitting diode die including second anode and cathode contacts respectively coupled to the third and fourth electrically conductive pads using metallic bonds, wherein widths of the metallic bonds between the second anode contact and the second pad and between the second cathode contact and the third pad are at least 60 percent of a width of the first light emitting diode die.

2. An electronic device according to claim 1 wherein the first light emitting diode die is asymmetrically mounted between the first and second electrically conductive pads, and wherein the second light emitting diode die is asymmetrically mounted between the third and fourth electrically conductive pads.

3. An electronic device according to claim 2 wherein there is at least a 25 percent difference between a contact area of the metallic bond between the first anode contact and the first pad and a contact area of the metallic bond between the first cathode contact and the second pad, and wherein there is at least a 25 percent difference between a contact area of the metallic bond between the second anode contact and the third pad and a contact area of the metallic bond between the second cathode contact and the fourth pad.

4. An electronic device according to claim 1 wherein a combined contact area of the metallic bonds between the first anode contact and the first pad and between the first cathode contact and the second pad is at least 70 percent of a surface area of the first light emitting diode die, and wherein a combined contact area of the metallic bonds between the second anode contact and the third pad and between the second cathode contact and the fourth pad is at least 70 percent of a surface area of the second light emitting diode die.

5. An electronic device according to claim 1 wherein the first and third electrically conductive pads comprise different portions of a continuous anode contact pad, and wherein the second and fourth electrically conductive pads comprise different portions of a continuous cathode contact pad.

6. An electronic device according to claim 5 wherein at least one of the electrically conductive pads defines a finger extending between opposing portions of another of the electrically conductive pads.

7. An electronic device according to claim 1 wherein the second and third electrically conductive pads comprises different portions of a continuous island contact pad.

8. An electronic device according to claim 1,

wherein the first light emitting diode die comprises a first diode region including therein a first n-type layer and a first p-type layer, wherein the first anode contact ohmically contacts the first p-type layer, and wherein the first cathode contact ohmically contacts the first n-type layer, and

wherein the second light emitting diode die comprises a second diode region including therein a second n-type layer and a second p-type layer, wherein the second anode contact ohmically contacts the second p-type layer, and wherein the second cathode contact ohmically contacts the second n-type layer.

9. An electronic device according to claim 1 further comprising:

a filler on the packaging substrate between the first and second electrically conductive pads and between the third and fourth electrically conductive pads, wherein the filler is reflective and electrically insulating.

10. An electronic device comprising:

a packaging substrate having a packaging substrate face; and

a plurality of light emitting diode die electrically and mechanically coupled to the packaging substrate, wherein each of the light emitting diode die comprises,

a diode region having first and second opposing faces and including therein an n-type layer and a p-type layer, wherein the first face is between the second face and the packaging substrate,

a anode contact that ohmically contacts the p-type layer and extends on the first face between the first face and the packaging substrate,

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

a substrate on the second face, wherein the diode region is between the substrate and the packaging substrate, and wherein the substrate has a thickness of at least about 50 micrometers.

11. An electronic device according to claim 10 wherein adjacent ones of the light emitting diode die are spaced apart by no more than about 250 micrometers.

12. An electronic device according to claim 10 wherein the substrate includes an inner face adjacent the second face, an outer face remote from the second face, and oblique sidewalls that extend from the outer face towards the second face.

13. An electronic device according to claim 10 further comprising:

a phosphor layer on each of the light emitting diode die opposite the packaging substrate, so that the substrate of each light emitting diode die is between the phosphor layer and the respective diode region.

14. An electronic device according to claim 10 wherein the plurality of light emitting diode die are arranged in lines with at least two of the lines including different numbers of light emitting diode die.

15. An electronic device according to claim 14 further comprising:

a lens that extends from the packaging substrate face to surround the plurality of light emitting diode die.

16. An electronic device according to claim 14 wherein a first line along an edge of the plurality of light emitting diode die includes fewer of the light emitting diode die than a second line in a central portion of the plurality of light emitting diode die.

17. An electronic device according to claim 14 wherein the light emitting diode die of two adjacent lines are offset.

18. An electronic device according to claim 14 wherein the lines define rows of an array, and wherein the light emitting diode die are further aligned in columns of the array perpendicular to the rows.

19. An electronic device comprising:

a packaging substrate having a packaging substrate face, wherein the packaging substrate has electrically conductive first and second pads on the packaging substrate face; and

an array of light emitting diode die on the packaging substrate face electrically coupled between the first and second pads, wherein the array of light emitting diode die are arranged in lines with at least two of the lines of the array including different numbers of light emitting diode die.

20. An electronic device according to claim 19 further comprising:

a lens that extends from the packaging substrate face to surround the array of light emitting diode die.

21. An electronic device according to claim 19 wherein a first line along an edge of the array includes fewer of the light emitting diode die than a second line in a central portion of the array.

22. An electronic device according to claim 19,

wherein each of the light emitting diode die comprises,

a diode region having first and second opposing faces and including therein an n-type layer and a p-type layer, wherein the first face is between the second face and the packaging substrate,

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

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

wherein each of the anode contacts of each of the light emitting diode die is electrically and mechanically bonded to the first pad, and

wherein each of the cathode contacts of each of the light emitting diode die is electrically and mechanically bonded to the second pad.

23. An electronic device according to claim 22 wherein at least one of the first and second pads defines a finger extending between opposing portions of another of the first and second pads.

24. An electronic device according to claim 19,

wherein the packaging substrate further includes a plurality of electrically conductive island pads between the first and second pads,

wherein each of the light emitting diode die comprises,

a diode region having first and second opposing faces and including therein an n-type layer and a p-type layer, wherein the first face is between the second face and the packaging substrate,

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

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

wherein the light emitting diode die are electrically coupled in series through the island pads and through the anode and cathode contacts between the first and second pads, so that each of the island pads is electrically and mechanically bonded to an anode contact of a respective first one of the light emitting diode die and to a cathode contact of a respective second one of the light emitting diode die.

25. An electronic device according to claim 19 wherein the light emitting diode die of two adjacent lines of the array are offset.

26. An electronic device according to claim 19 wherein the lines define rows of the array, and wherein the light emitting diode die are aligned in columns perpendicular to the rows.

27. An electronic device according to claim 19 wherein adjacent ones of the light emitting diode die are spaced apart by no more than about 250 micrometers.

28. An electronic device comprising:

a packaging substrate having a packaging substrate face, the packaging substrate comprising,

first and second electrically conductive pads on the packaging substrate face, and

a filler between the first and second electrically conductive pads wherein the filler is reflective and electrically insulating; and

a light emitting diode die comprising,

a diode region having first and second opposing faces and 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, wherein the anode contact is electrically and mechanically bonded to the first electrically conductive pad of the packaging substrate, and

a cathode contact that ohmically contacts the n-type layer and that also extends on the first face, wherein the cathode contact is electrically and mechanically bonded to the second electrically conductive pad of the packaging substrate.

29. An electronic device according to claim 28 wherein the light emitting diode die further includes,

a substrate on the second face, wherein the diode region is between the substrate and the packaging substrate, and wherein the substrate has a thickness of at least about 50 micrometers.

30. An electronic device according to claim 29 further comprising:

a phosphor layer on the substrate opposite the packaging substrate so that the substrate is between the phosphor layer and the diode region.

31. An electronic device according to claim 28 wherein the light emitting diode die comprises a first light emitting diode die, wherein the diode region comprises a first diode region, wherein the anode contact comprises a first anode contact, and wherein the cathode contact comprises a first cathode contact, the electronic device further comprising:

a second light emitting diode die comprising,

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

a second anode contact that ohmically contacts the p-type layer and extends on the first face, wherein the second anode contact is electrically and mechanically bonded to the first electrically conductive pad of the packaging substrate, and

a second cathode contact that ohmically contacts the n-type layer and that also extends on the first face, wherein the second cathode contact is electrically and mechanically bonded to the second electrically conductive pad of the packaging substrate.

32. An electronic device according to claim 31 wherein the first and second light emitting diode die are spaced apart by no more than about 250 micrometers.

33. An electronic device according to claim 28 wherein the light emitting diode die comprises a first light emitting diode die, wherein the diode region comprises a first diode region, wherein the anode contact comprises a first anode contact, and wherein the cathode contact comprises a first cathode contact, wherein the packaging substrate further comprises a third electrically conductive pad, and wherein the filler surrounds the second electrically conductive pad, the electronic device further comprising:

a second light emitting diode die comprising,

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

a second anode contact that ohmically contacts the p-type layer and extends on the first face, wherein the second anode contact is electrically and mechanically bonded to the second electrically conductive pad of the packaging substrate, and

a second cathode contact that ohmically contacts the n-type layer and that also extends on the first face, wherein the second cathode contact is electrically and mechanically bonded to the third electrically conductive pad of the packaging substrate.

34. An electronic device according to claim 33 wherein the first and second light emitting diode die are spaced apart by no more than about 250 micrometers.

35. An electronic device according to claim 28 wherein the filler material and the packaging substrate comprise different materials.

36. An electronic device comprising:

a packaging substrate having a packaging substrate face; and

a plurality of light emitting diode die electrically and mechanically coupled to the packaging substrate, wherein each of the light emitting diode die comprises,

a diode region having first and second opposing faces and including therein an n-type layer and a p-type layer, wherein the first face is between the second face and the packaging substrate,

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

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

a phosphor layer on each of the light emitting diode die opposite the packaging substrate, wherein portions of the diode region of each of the light emitting diode die is separated from the phosphor layer by a distance of at least about 50 micrometers.

37. An electronic device according to claim 36 wherein each of the light emitting diode die further comprises,

a substrate on the second face between the second face and the phosphor layer, the substrate including an inner face adjacent the second face, an outer face remote from the second face, and sidewalls that extend from the outer face towards the second face.

38. An electronic device according to claim 36 wherein the phosphor layer comprises a continuous phosphor layer extending across each of the plurality of light emitting diode die and portions of the packaging substrate between the light emitting diode die.

39. An electronic device according to claim 38 wherein a thickness of the continuous phosphor layer is less than a thickness of one of the light emitting diode die.

40. An electronic device according to claim 38 wherein a thickness of the continuous phosphor layer is greater than a thickness of one of the light emitting diode die.

41. An electronic device according to claim 36 wherein the phosphor layer comprises a plurality of separate phosphor layers, wherein each of the separate phosphor layers is on a respective one of the light emitting diode die.

42. An electronic device comprising:

a submount;

a plurality of light emitting diode (LED) die electrically and mechanically bonded to the submount, wherein each of the light emitting diode die comprises,

a diode region having first and second opposing faces and including therein an n-type layer and a p-type layer, wherein the first face is between the second face and the packaging substrate,

a anode contact that ohmically contacts the p-type layer and extends on the first face between the first face and the packaging substrate, and

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

wherein adjacent LED die are spaced apart by distances in the range of about 20 micrometers to about 500 micrometers.

43. An electronic device according to claim 42 wherein the plurality of LED die are electrically coupled in series, wherein each of the plurality of LED die has a forward operating voltage in the range of about 2 volts to about 4 volts, and wherein a forward operating voltage of the serially coupled plurality of LED die is at least about 12 volts.

44. An electronic device according to claim 42 wherein the plurality of LED die are electrically coupled in parallel.

45. An electronic device according to claim 42 wherein the plurality of LED die comprise at least four light emitting diode die.

46. An electronic device according to claim 42 wherein the plurality of LED die are bonded to a surface of the submount having a surface are of less than about 85 mm².

47. A method of forming an electronic device, the method comprising:

sequentially placing each of a plurality of light emitting diode (LED) die on a submount, wherein each of the light emitting diode die comprises,

a diode region having first and second opposing faces and including therein an n-type layer and a p-type layer, wherein the first face is between the second face and the packaging substrate,

a anode contact that ohmically contacts the p-type layer and extends on the first face between the first face and the packaging substrate, and

a cathode contact that ohmically contacts the n-type layer and extends on the first face between the first face and the packaging substrate; and

performing a reflow operation to provide a metallic bond between anode and cathode contacts of each of the LED die and the submount.

48. A method according to claim 47 wherein adjacent LED die are spaced apart by distances in the range of about 20 micrometers to about 500 micrometers.

49. A method according to claim 47 wherein the plurality of LED die are electrically coupled in series, wherein each of the plurality of LED die has a forward operating voltage in the range of about 2 volts to about 4 volts, and wherein a forward operating voltage of the serially coupled plurality of LED die is at least about 12 volts.

50. A method according to claim 47 wherein the plurality of LED die are electrically coupled in parallel.

51. A method according to claim 47 wherein the plurality of LED die comprise at least four light emitting die.

52. A method according to claim 47 wherein the plurality of LED die are placed on a surface of the submount having a surface are of less than about 85 mm².