Multi-chip LED devices

• US 8,696,159 B2
• Filed: 01/31/2011
• Issued: 04/15/2014
• Est. Priority Date: 09/20/2010
• Status: Active Grant

• Current Assignee: CREE Led Incorporated (Smart Global Holdings Incorporated)
• Original Assignee: CREE Incorporated (Wolfspeed, Inc.)
• Inventors: Andrews, Peter Scott, Rosado, Raymond, Laughner, Michael P., Emerson, David T., Britt, Jeffrey C.
• Primary Examiner(s): Neils, Peggy A.
• Application Number:
  US13/017,407
• Publication Number:
  US 20120069564A1
• Time in Patent Office: 1,170 Days
• Field of Search: 362/249.02, 362/231, 362/800, 362/311.02, 257/88, 257/98, 257/100, 257/99
• US Class Current: 362/249.02
• CPC Class Codes: H01L 2224/48091 Arched
• CPC Class Codes: H01L 25/0753 the devices being arranged next to each other
• 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 33/486 adapted for surface mounting
• CPC Class Codes: H01L 33/58 Optical field-shaping elements
• 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: Y10T 29/49002 Electrical device making

Abstract

Multi-chip LED devices are described. Embodiments of the present invention provide multi-chip LED devices with relatively high efficiency and good color rendering. The LED device includes a plurality of interconnected LED chips and an optical element such as a lens. The optical element may be molded from silicone. The LED chips may be connected in parallel. In some embodiments, the LED device includes a submount, which may be made of a ceramic material such as alumina or aluminum nitride. Wire bonds can be connected to the LED chips so that all the wire bonds tend the outside of a group of LED chips. Various sizes and types of LED chips may be used, including vertical LED chips and sideview LED chips.

Claims

1. An LED device comprising:

a plurality of interconnected LED chips, wherein each of the LED chips has a first terminal connected to a metal portion of a submount to which the plurality of interconnected LED chips is fastened and a second terminal connected with a wire bond so that the wire bonds connected to second terminals connect to the submount to the outside of the plurality of interconnected LED chips; and

an optical element disposed to affect light from the LED chips;

wherein the optical element is less than 5 mm in diameter while maintaining a clearance between a circle circumscribing the LED chips at their widest point and an edge of the optical element such that the clearance is from approximately 0.2 to 0.8 the width of the circle.

2. The LED device of claim 1 wherein the optical element is less than 4 mm in diameter.

3. The LED device of claim 2 wherein the clearance is from approximately 0.3 to 0.65 the width of the circle.

4. The LED device of claim 2 wherein the LED chips are connected in parallel and the submount comprises ceramic.

5. The LED device of claim 4 wherein the optical element is molded from silicone.

6. The LED device of claim 5 wherein the first terminals of at least some of the plurality of interconnected LED chips are in contact with the metal portion of the submount.

7. The LED device of claim 6 where, when the LED chips are energized, the device emits light with an efficiency of at least 80 lm/W and a color rendering index of at least 80.

8. The LED device of claim 7 wherein the optical element is about 3.1 mm in diameter, the efficiency is at least about 89 lm/W and the CRI is at least 82.

9. The LED device of claim 5 wherein at least some of the plurality of interconnected LED chips are sideview LED chips.

10. The LED device of claim 9 where, when the LED chips are energized, the device emits light with an efficiency of at least 80 lm/W and a color rendering index of at least 80.

11. The LED device of claim 10 wherein the optical element is about 3.1 mm in diameter, the efficiency is at least about 89 lm/W and the CRI is at least 82.

12. An LED device comprising:

a submount;

a plurality of LED chips fixed to the submount, at least some of the plurality of LED chips having connection points for both an anode and a cathode on one side, each of the plurality of LED chips having a first terminal connected to a metal portion of the submount to which the plurality of LED chips is fixed;

a plurality of wire bonds, each connected between a second terminal of an LED chip and the submount, the plurality of wire bonds arranged so that all the wire bonds connect to the submount to the outside of the plurality of LED chips; and

an optical element disposed to affect light from the plurality of LED chips.

13. The LED device of claim 12 wherein the optical element comprises silicone and the submount comprises ceramic.

14. The LED device of claim 13 wherein at least some of the plurality of LED chips are connected in parallel.

15. The LED device of claim 14 wherein the plurality of LED chips comprises four LED chips.

16. The LED device of claim 15 wherein the first terminals of at least some of the plurality of LED chips are in contact with the metal portion of the submount.

17. The LED device of claim 16 where, when the LED chips are energized, the device emits light with an efficiency of at least 80 lm/W and a color rendering index of at least 80.

18. The LED device of claim 17 wherein the optical element is about 3.1 mm in diameter, the efficiency is at least about 89 lm/W and the CRI is at least 82.

19. An LED device comprising:

a ceramic submount;

a plurality of LED chips fixed to the submount, at least some of the plurality of LED chips having connection points for both an anode and a cathode on one side,

wherein each of the LED chips has a first terminal connected to a metal portion of the ceramic submount to which the LED chips are fastened and a second terminal connected with a wire bond so that the wire bonds connected to second terminals connect to the ceramic submount to the outside of the plurality of LED chips; and

a silicone lens disposed to affect light from the plurality LED chips.

20. The LED device of claim 19 wherein at least some of the plurality of LED chips are in contact with the metal portion of the submount.

21. The LED device of claim 20 where, when the LED chips are energized, the device emits light with an efficiency of at least 80 lm/W and the CRI is at least 80.

22. The LED device of claim 21 wherein the optical element is about 3.1 mm in diameter, the efficiency is at least about 89 lm/W and the CRI is at least 82.

23. A method of assembling an LED device, the method comprising:

selecting a plurality of LED chips;

fixing the plurality of LED chips to a ceramic submount, each of the plurality of LEDs having a first terminal connected to a metal portion of the submount to which the plurality of LED chips is fixed;

interconnecting the plurality of LED chips at least in part with wire bonds, each of a plurality of the wire bonds connected between a second terminal of an LED chip and the submount, the plurality of wire bonds arranged so that the wire bonds connect to the submount to the outside of the plurality of LED chips; and

attaching a silicone lens to the ceramic submount to affect light from the LED chips, wherein the silicone lens is less than 5 mm in diameter while maintaining a clearance between a circle circumscribing the LED chips at their widest point and an edge of the silicone lens such that the clearance is from approximately 0.2 to 0.8 the width of the circle.

24. The method of claim 23 further comprising making the ceramic submount from alumina.

25. The method of the LED device of claim 24 wherein at least some of the plurality of LED chips are in contact with the metal portion of the submount.

26. The method of the LED device of claim 24 wherein at least some of the plurality of LED chips are sideview LED chips.

27. The method of claim 23 further comprising making the ceramic submount from aluminum nitride.

28. The method of the LED device of claim 27 wherein at least some of the plurality of LED chips are in contact with the metal portion of the submount.

29. The method of the LED device of claim 27 wherein at least some of the plurality of LED chips are sideview LED chips.