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

• US 9,053,958 B2
• Filed: 05/03/2012
• Issued: 06/09/2015
• 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): Lee, Cheung
• Assistant Examiner(s): BRADLEY, STEPHEN M
• Application Number:
  US13/463,267
• Publication Number:
  US 20120305949A1
• Time in Patent Office: 1,132 Days
• Field of Search: 257/81, 257/88, 257/92, 257/93, 438/26, 438/29
• US Class Current: 1/1
• 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 33/54 having a particular shape

Abstract

An electronic device may include a packaging substrate having a packaging face and first and second pluralities of light emitting diodes electrically and mechanically coupled to the packaging face of the packaging substrate. The packaging substrate may include first and second electrically conductive pads on the packaging face. The light emitting diodes of the first plurality of light emitting diodes may be electrically coupled in parallel between the first electrically conductive pad and an interconnection structure on the packaging face. The light emitting diodes of the second plurality of light emitting diodes may be electrically coupled in parallel between the interconnection structure and the second electrically conductive pad.

Claims

1. An electronic device comprising:

a packaging substrate having a packaging face, the packaging substrate including first, second, and third electrically conductive structures on the packaging face; and

first and second pluralities of light emitting diodes electrically and mechanically coupled to the packaging face of the packaging substrate, wherein the light emitting diodes of the first plurality of light emitting diodes are electrically coupled in parallel between the first electrically conductive structure and the second electrically conductive structure on the packaging face, wherein the light emitting diodes of the second plurality of light emitting diodes are electrically coupled in parallel between the second electrically conductive structure and the third electrically conductive structure, wherein the packaging substrate is free of wirebonds electrically coupled between the packaging substrate and any of light emitting diodes of the first and second pluralities of light emitting diodes, and wherein each of the light emitting diodes has a forward voltage drop of at least 2.5 volts so that a voltage drop between the first and third electrically conductive structures is at least 5.0 volts,

wherein the first electrically conductive structure and the second electrically conductive structure define an electrically insulating gap therebetween wherein a portion of the electrically insulating gap that is between first and second light emitting diodes of the first plurality of light emitting diodes has a width that is less than a width of the first light emitting diode, and

wherein the electrically insulating gap comprises a first linear portion and a second linear portion which are separated by a non-linear portion, wherein the first and second linear portions of the gap and the non-linear portion of the gap define an extension of the first electrically conductive structure, wherein the first and second linear portions of the gap define respective first and second sides of the extension of the first electrically conductive structure, wherein a first portion of the second electrically conductive structure is adjacent to the first side of the extension, wherein a second portion of the second electrically conductive structure is adjacent to the second side of the extension, wherein the first light emitting diode spans the first linear portion of the gap from the first side of the extension to the first portion of the second electrically conductive structure, and wherein the second light emitting diode spans the second linear portion of the gap from the second side of the extension to the second portion of the second electrically conductive structure.

2. The electronic device of claim 1, wherein each of the light emitting diodes has a forward voltage drop of at least 2.8 volts so that a voltage drop between the first and third electrically conductive structures is at least 5.6 volts.

3. The electronic device of claim 1, wherein the first plurality of light emitting diodes includes first and second strings of light emitting diodes with respective light emitting diodes of the first string being electrically coupled in series between the first and second electrically conductive structures, with respective light emitting diodes of the second string being electrically coupled in series between the first and second electrically conductive structures, and with the first and second strings being electrically coupled in parallel between the first and second electrically conductive structures, and wherein the second plurality of light emitting diodes includes third and fourth strings of light emitting diodes with respective light emitting diodes of the third string being electrically coupled in series between the second and third electrically conductive structures, with respective light emitting diodes of the fourth string being electrically coupled in series between the second and third electrically conductive structures, and with the third and fourth strings being electrically coupled in parallel between the second and third electrically conductive structures.

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

5. The electronic device of claim 1, wherein the first electrically conductive structure comprises a first electrically conductive pad, wherein the second electrically conductive structure comprises an electrically conductive interconnection structure, and wherein the third electrically conductive structure comprises a second electrically conductive pad.

6. The electronic device of claim 1, wherein the first, second, and third electrically conductive structures comprise respective first, second, and third electrically conductive interconnection structures.

7. The electronic device of claim 1, wherein the first electrically conductive structure comprises a first electrically conductive pad, wherein the second electrically conductive structure comprises a first electrically conductive interconnection structure, and wherein the third electrically conductive structure comprises a second electrically conductive interconnection structure.

8. The electronic device of claim 1, wherein the width of the electrically insulating gap is a distance between the first electrically conductive structure and the second electrically conductive structure measured in the portion of the electrically insulating gap that is between the first and second light emitting diodes.

9. The electronic device of claim 1, wherein the width of the electrically insulating gap is about 75 μ

m or less.

10. The electronic device of claim 1, wherein a maximum width of the electrically insulating gap between the first and second light emitting diodes is less than the width of first light emitting diode.

11. The electronic device of claim 1, wherein a maximum width of the electrically insulating gap between the first electrically conductive structure and the second electrically conductive structure measured in the portion of the electrically insulating gap between the first and second light emitting diodes is less than the width of the first light emitting diode.

12. The electronic device of claim 1, wherein the first linear portion is parallel to the second linear portion.

13. The electronic device of claim 1,

wherein the electrically insulating gap is a first electrically insulating gap,

wherein the second electrically conductive structure and the third electrically conductive structure define a second electrically insulating gap therebetween, and

wherein a portion of the second electrically insulating gap that is between first and second light emitting diodes of the second plurality of light emitting diodes has a width that is less than the width of the first light emitting diode of the second plurality of light emitting diodes.

14. The electronic device of claim 13, wherein the first electrically insulating gap connects to the second electrically insulating gap.

15. The electronic device of claim 1, further comprising a reflective material in the electrically insulating gap.

16. The electronic device of claim 1, wherein the packaging substrate has a backside face opposite the packaging face, the electronic device further comprising:

a first backside electrical contact on the backside face; and

a second backside electrical contact on the backside face wherein the first, second, and third electrically conductive structures are electrically connected in series between the first and second backside electrical contacts.

17. The electronic device of claim 16, wherein the packaging substrate further includes a fourth electrically conductive structure on the packaging face, the electronic device further comprising:

a third plurality of light emitting diodes electrically and mechanically coupled to the packaging face of the packaging substrate, wherein the light emitting diodes of the third plurality of light emitting diodes are electrically coupled in parallel between the third electrically conductive structure and the fourth electrically conductive structure, and wherein each of the light emitting diodes of the third plurality of light emitting diodes has a forward voltage drop of at least 2.5 volts so that a voltage drop between the first and fourth electrically conductive structures is at least 7.5 volts, and wherein the first, second, third, and fourth electrically conductive structures are electrically coupled in series between the first and second backside electrical contacts.

18. The electronic device of claim 17 wherein each of the light emitting diodes has a forward voltage drop of at least 2.8 volts so that a voltage drop between the first and fourth electrically conductive structures is at least 8.4 volts.

19. The electronic device of claim 1, wherein the first plurality of light emitting diodes includes third and fourth light emitting diodes, wherein the third light emitting diode spans the first linear portion of the gap from the first side of the extension to the first portion of the second electrically conductive structure, and wherein the fourth light emitting diode spans the second linear portion of the gap from the second side of the extension to the second portion of the second electrically conductive structure.

20. The electronic device of claim 19, wherein the extension of the first electrically conductive structure extends between the first and second linear portions of the electrically insulating gap and between the first and second portions of the second electrically conductive structure.

21. The electronic device of claim 1, wherein the first and second linear portions of the gap and the first and second sides of the extension are between the first and second portions of the second electrically conductive structure, wherein the extension of the first electrically conductive structure is continuous between the first and second linear portions of the gap and between the first and second light emitting diodes, and wherein the first and second portions of the second electrically conductive structure are on opposite sides of the extension of the first electrically conductive structure.

22. The electronic device of claim 16 further comprising:

a thermally conductive pad on the backside face of the packaging substrate between the first and second backside electrical contacts.

23. The electronic device of claim 16 further comprising:

a continuous optical coating on the first and second pluralities of light emitting diodes.

24. An electronic device comprising:

a packaging substrate having a packaging face, the packaging substrate including first and second electrically conductive structures on the packaging face; and

a plurality of light emitting diodes electrically and mechanically coupled to the packaging face of the packaging substrate, wherein the light emitting diodes are electrically coupled in parallel between the first electrically conductive structure and the second electrically conductive structure on the packaging face, wherein the packaging substrate is free of wirebonds electrically coupled between the packaging substrate and the light emitting diodes,

wherein the first electrically conductive structure and the second electrically conductive structure define an electrically insulating gap therebetween wherein a portion of the electrically insulating gap that is between first and second light emitting diodes of the plurality of light emitting diodes has a width that is less than a width of the first light emitting diode, and

wherein the electrically insulating gap comprises a first linear portion and a second linear portion which are separated by a non-linear portion, wherein the first and second linear portions of the gap and the non-linear portion of the gap define an extension of the first electrically conductive structure, wherein the first and second linear portions of the gap define respective first and second sides of the extension of the first electrically conductive structure, wherein a first portion of the second electrically conductive structure is adjacent to the first side of the extension, wherein a second portion of the second electrically conductive structure is adjacent to the second side of the extension, wherein the first light emitting diode spans the first linear portion of the gap from the first side of the extension to the first portion of the second electrically conductive structure, and the second light emitting diode spans the second linear portion of the gap from the second side of the extension to the second portion of the second electrically conductive structure.

25. The electronic device of claim 24, wherein the width of the electrically insulating gap is a distance between the first electrically conductive structure and the second electrically conductive structure measured in the portion of the electrically insulating gap that is between first and second light emitting diodes of the plurality of light emitting diodes.

26. The electronic device of claim 24, wherein the width of the electrically insulating gap is about 75 μ

m or less.

27. The electronic device of claim 24, wherein a maximum width of the electrically insulating gap between the first and second light emitting diodes is less than the width of first light emitting diode.

28. The electronic device of claim 24, wherein a maximum width of the electrically insulating gap measured in the portion of the electrically insulating gap between the first and second light emitting diodes in a direction perpendicular to an edge of the gap is less than the width of the first light emitting diode in the direction perpendicular to the edge of the gap.

29. The electronic device of claim 24, wherein the first linear portion is parallel to the second linear portion.

30. The electronic device of claim 24, further comprising a reflective material in the electrically insulating gap.

31. The electronic device of claim 24, wherein the non-linear portion is between the first and second light emitting diodes.

32. The electronic device of claim 24, wherein the plurality of light emitting diodes includes third and fourth light emitting diodes, wherein the third light emitting diode spans the first linear portion of the gap from the first side of the extension to the first portion of the second electrically conductive structure, and wherein the fourth light emitting diode spans the second linear portion of the gap from the second side of the extension to the second portion of the second electrically conductive structure.

33. The electronic device of claim 32, wherein the extension of the first electrically conductive structure extends between the first and second linear portions of the electrically insulating gap and between the first and second portions of the second electrically conductive structure.

34. The electronic device of claim 24, wherein the first and second linear portions of the gap and the first and second sides of the extension are between the first and second portions of the second electrically conductive structure, wherein the extension of the first electrically conductive structure is continuous between the first and second linear portions of the gap and between the first and second light emitting diodes, and wherein the first and second portions of the second electrically conductive structure are on opposite sides of the extension of the first electrically conductive structure.

35. The electronic device of claim 24, wherein the packaging substrate has a backside face opposite the packaging face, the electronic device further comprising:

a first backside electrical contact on the backside face; and

a second backside electrical contact on the backside face wherein the first and second electrically conductive structures are electrically coupled in series between the first and second backside electrical contacts.

36. The electronic device of claim 35 further comprising:

a thermally conductive pad on the backside face of the packaging substrate between the first and second backside electrical contacts.

37. The electronic device of claim 35 further comprising:

a continuous optical coating on the first and second pluralities of light emitting diodes.