LIGHT EMITTING DEVICES AND METHODS

• US 20120126255A1
• Filed: 02/16/2011
• Published: 05/24/2012
• Est. Priority Date: 11/22/2010
• Status: Active Grant

• Current Assignee: Creeled Incorporated
• Original Assignee: CREE Incorporated (Wolfspeed, Inc.)
• Inventors: Hussell, Christopher P., Andrews, Peter Scott, Reiherzer, Jesse Colin, Emerson, David T.
• Granted Patent: US 8,564,000 B2
• Time in Patent Office: Days
• US Class Current: 257/88
• CPC Class Codes: H01L 2224/48091 Arched
• CPC Class Codes: H01L 2224/48137 the bodies being arranged next to each other, e.g. on a common substrate
• CPC Class Codes: H01L 25/0753 the devices being arranged next to each other
• CPC Class Codes: H01L 25/167 comprising optoelectronic devices, e.g. LED, photodiodes
• 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 33/52 Encapsulations
• 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

Light emitting devices and methods are disclosed. In one embodiment a light emitting device can include a substrate, one or more light emitting diodes (LEDs) disposed over the substrate, and the LEDs can include electrical connectors for connecting to an electrical element. A light emitting device can further include a retention material disposed over the substrate and the retention material can be disposed over at least a portion of the electrical connectors. In one aspect, a method for making a light emitting device is disclosed. The method can include providing a substrate with one or more LEDs comprising electrical connectors. The method can further include providing a retention material on at least a portion of the substrate wherein the retention material is disposed over at least a portion of the electrical connectors.

Claims

1. A light emitting device comprising:

a substrate;

one or more light emitting diodes (LEDs) disposed over the substrate, the LEDs comprising electrical connectors; and

a retention material disposed over the substrate, wherein the retention material is disposed over at least a portion of the electrical connectors.

2. The light emitting device of claim 1 wherein the retention material is dispensed on the substrate.

3. The light emitting device of claim 1 wherein an upper surface of the retention material opposite the substrate has a curved cross section.

4. The light emitting device of claim 1 further comprising at least one electrostatic discharge device (ESD) and wherein the electrostatic discharge device (ESD) is at least partially covered by the retention material.

5. The light emitting device of claim 1 wherein at least some of the LEDs are arranged in a checkerboard configuration.

6. The light emitting device of claim 5 wherein the LEDs are disposed in a plurality of strings each comprising a predetermined number of LEDs.

7. The light emitting device of claim 6 wherein there are at least 14 LEDs disposed on each string and a total of at least 140 LEDs.

8. The light emitting device of claim 1 wherein the electrical connectors comprise wirebonds.

9. The light emitting device of claim 1 wherein the substrate comprises one or more intervening layers disposed between the retention material and the substrate.

10. A light emitting device comprising:

a substrate;

at least one conductive trace electrically connected with the substrate;

an array of LEDs electrically connected with the at least one conductive trace, the LEDs comprising wirebonds; and

a retention material disposed over the substrate, wherein the retention material is disposed over at least a portion of the wirebonds.

11. The light emitting device of claim 10 wherein the retention material retains a fill material at least partially disposed over the array of LEDs.

12. The light emitting device of claim 11 wherein the fill material at least partially comprises a phosphor or other material for affecting a color of light emitted from the array of LEDs.

13. The light emitting device of claims 10 wherein the retention material is disposed over at least a portion of each of the at least one conductive trace and a solder mask, the solder mask at least partially disposed over a portion of the substrate.

14. The light emitting device of claims 10 wherein the retention material is disposed over at least a portion of the at least one conductive trace to which at least a first LED of the array of LEDs is electrically connected.

15. The light emitting device of claim 10 further comprising one or more attachment surfaces on the surface of substrate for electrically connecting the light emitting device to an external power source.

16. The light emitting device of claim 15 wherein the attachment surfaces comprise solder contacts.

17. The light emitting device of claim 10 wherein the substrate comprises one or more intervening layers disposed between the retention material and the substrate.

18. A method for making a light emitting device, the method comprising:

providing a substrate with one or more light emitting diodes (LEDs) disposed over the substrate, the one or more LEDs comprising electrical connectors; and

providing a retention material on at least a portion of the substrate wherein the retention material is disposed over at least a portion of the electrical connectors.

19. The method of claim 18 wherein providing retention material comprises dispensing retention material.

20. The method of claim 18 further comprising forming an upper surface of the retention material, the upper surface formed opposite the substrate and comprising a curved cross-section.

21. The method of claim 18 wherein providing the retention material comprises dispensing the retention material over at least partially over each of a solder mask and at least one conductive trace, the solder mask and conductive trace attached to or electrically connected with the substrate.

22. The method of claim 18 wherein the retention material is disposed over at least a portion at least one conductive trace to which at least a first LED of the one or more LEDs is electrically connected.

23. The method of claim 18 wherein the LEDs are arranged at least partially in a checkerboard configuration.

24. The method of claim 18 further comprising providing at least one electrostatic discharge device (ESD) and positioning the at least one ESD device at least partially within the retention material.

25. The method of claim 18 further comprising providing a fill material over the one or more LEDs wherein the fill material is retained in place at least partially by the retention material.

26. A method for fine-tuning color of light emitted from a light emitting device, the method comprising:

providing a light emitting device comprising at least one or more light emitting diodes (LEDs) disposed on a substrate of the light emitting device;

providing a fill material to at least partially cover the one or more LEDs;

providing a retention material on the substrate for retaining a volume of fill material over the one or more LEDs; and

selectively controlling a volume of the fill material such that color-affecting components of the fill material can be fine-tuned such that light produced by the one or more LEDs is within a predetermined and precise color range.

27. The method of claim 26 wherein step of selectively controlling the volume of the fill material comprises dispensing the retention material in a predetermined location on the substrate providing a suitable distance between the retention material and the one or more LEDs.

28. The method of claim 26 wherein the step of providing a fill material comprises providing an encapsulant having a predetermined amount of phosphors.

29. A light emitting device comprising:

a substrate;

at least two or more strings of light emitting diodes (LEDs) disposed over the substrate, each string comprising a plurality of LEDs electrical connected in series; and

a retention material disposed over the substrate, wherein the retention material is disposed over at least a portion of the electrical connectors.

30. A light emitting device, comprising:

a substrate;

a first plurality of light emitting diodes (LEDs) disposed over the substrate in a first pattern;

a second plurality of LEDs disposed over the substrate in a second pattern; and

wherein the first pattern is different from the second pattern.

31. The light emitting device of claim 30 further comprising a retention material disposed on the substrate at least partially disposed around the first and second patterns.

32. The light emitting device of claim 31, wherein the LEDs comprise electrical connectors and wherein the retention material is disposed over at least a portion of the electrical connectors.

33. The light emitting device of claim 32 wherein the electrical connectors comprise wirebonds.

34. The light emitting device of claim 30, wherein at least one of the first or second pluralities of LEDS comprises LEDs electrically connected in series.

35. The light emitting device of claim 30, wherein the first and second patterns comprise at least two of the following arrangements:

(i) a checkerboard arrangement;

(ii) a straight line arrangement; and

(iii) a grid arrangement wherein the LEDs are substantially aligned in at least two directions.

36. The light emitting device of claim 35, wherein the first and second patterns comprise a combination of any two of the checkerboard, straight line, or grid arrangements.

37. The light emitting device of claim 30 further comprising a third plurality of LEDS disposed over the substrate in a third pattern that is different from the first and second patterns.

38. The light emitting device of claim 37, wherein the first plurality comprises a first set of LEDs, the second plurality comprises a second set of LEDs, and the third plurality comprises a third set of LEDs, and wherein each set of LEDs is disposed over the substrate.

39. The light emitting device of claim 30, wherein the LEDs of at least one of the first and second plurality of LEDs are arranged in different arrangements over the substrate.

40. The light emitting device of claim 39, wherein the first plurality of LEDs comprise LEDs arranged in parallel with LEDs of the second plurality of LEDs.

41. The light emitting device of claim 30, wherein the first plurality of LEDs comprises rectangular LEDs in a first orientation and the second plurality of LEDs comprises rectangular LEDs in a second orientation different from the first orientation.

42. The light emitting device of claim 30, wherein at least a first LED of the first plurality of LEDs comprises a rectangular LED in a first orientation and at least a second LED of the first plurality of LEDs comprises a rectangular LED in a second orientation different from the first orientation.

43. A method of making a light emitting device, the method comprising:

providing a substrate;

providing a first plurality of light emitting diodes (LEDs) comprising a first pattern;

providing a second plurality of LEDs comprising a second pattern; and

arranging each of the first and second patterns over the substrate, wherein the first pattern is different from the second pattern.

44. The method of claim 43, further comprising providing a retention material for retaining a volume of fill material over the one or more LEDs.

45. The method of claim 43, further comprising providing a third plurality of LEDs comprising a third pattern, wherein the third pattern is different than the first and second patterns.

46. The method of claim 43, wherein arranging each of the first and second patterns over the substrate comprises alternating the first and second patterns.

47. The method of claim 43, wherein providing the first and second pattern comprises providing at least two of the following:

(i) a checkerboard arrangement;

(ii) a straight line arrangement;

or

(iii) a grid arrangement wherein the LEDs are substantially aligned in at least two directions.

48. The method of claim 43, wherein providing a first plurality comprises providing a first set of LEDs in series, and wherein providing a second plurality comprises providing a second set of LEDs in series.

49. The method of claim 48, wherein providing first and second sets comprises providing more than one of each of the first and second sets.