LIGHT EMITTING DIODES AND METHODS

• US 20180076368A1
• Filed: 08/14/2017
• Published: 03/15/2018
• Est. Priority Date: 03/31/2015
• Status: Active Application

• Current Assignee: CREE Incorporated (Wolfspeed, Inc.)
• Original Assignee: CREE Incorporated (Wolfspeed, Inc.)
• Inventors: Hussell, Christopher P.
• Application Number:
  US15/676,965
• Publication Number:
  US 20180076368A1
• Time in Patent Office: Days
• CPC Class Codes: H01L 2224/13101 the principal constituent melting at a temperature of less than 400°C
• CPC Class Codes: H01L 2224/16225 the item being non-metallic, e.g. insulating substrate with or without metallisation
• CPC Class Codes: H01L 2224/29101 the principal constituent melting at a temperature of less than 400°C
• CPC Class Codes: H01L 2224/32225 the item being non-metallic, e.g. insulating substrate with or without metallisation
• CPC Class Codes: H01L 2224/45099 Material
• CPC Class Codes: H01L 2224/48227 connecting the wire to a bond pad of the item
• CPC Class Codes: H01L 2224/48471 the other connecting portion not on the bonding area being a ball bond, i.e. wedge-to-ball, reverse stitch
• CPC Class Codes: H01L 2224/73265 Layer and wire connectors
• CPC Class Codes: H01L 24/13 of an individual bump connector
• CPC Class Codes: H01L 24/16 of an individual bump connector
• CPC Class Codes: H01L 24/29 of an individual layer connector
• CPC Class Codes: H01L 24/48 of an individual wire connector
• CPC Class Codes: H01L 24/73 Means for bonding being of different types provided for in two or more of groups H01L24/10, H01L24/18, H01L24/26, H01L24/34, H01L24/42, H01L24/50, H01L24/63, H01L24/71
• 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 2924/00012 Relevant to the scope of the group, the symbol of which is combined with the symbol of this group
• 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 2924/014 Solder alloys
• CPC Class Codes: H01L 2924/12041 LED
• CPC Class Codes: H01L 2924/181 Encapsulation
• CPC Class Codes: H01L 2933/005 : relating to encapsulations
• CPC Class Codes: H01L 2933/0058 : relating to optical field-shaping elements
• CPC Class Codes: H01L 33/52 : Encapsulations
• CPC Class Codes: H01L 33/54 : having a particular shape
• CPC Class Codes: H01L 33/56 : Materials, e.g. epoxy or silicone resin
• CPC Class Codes: H01L 33/58 : Optical field-shaping elements
• CPC Class Codes: H01L 33/60 : Reflective 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

Abstract

Light emitting diode (LED) devices, methods and systems are provided. An example apparatus can include an underfill layer separate from a bonding layer. The apparatus can further include a dark encapsulating layer comprising an epoxy-molded compound which is applied using a powder-coating process. A method for providing a powder-coated encapsulation and for producing an LED panel with such an encapsulant is disclosed.

Claims

1. A light emitting diode (LED) apparatus, comprising:

a substrate;

one or more light emitting diode (LED) disposed over the substrate; and

an encapsulant layer applied after the one or more LED is disposed over the substrate, wherein the encapsulant layer comprises an underfill layer;

wherein the encapsulant layer is disposed around the one or more LED and at least partially between the one or more LEDs and the substrate,

wherein the one or more LED is devoid of any reflective material on a lower surface of the one or more LED facing the substrate.

2. The LED apparatus of claim 1, wherein the encapsulant layer does not cover a top surface of the one or more LEDs.

3. The LED apparatus of claim 1, wherein the encapsulant layer is a reflective material.

4. The LED apparatus of claim 1, wherein the encapsulant layer is a non-reflective material.

5. A method of controlling light output, comprising

providing a substrate and one or more light emitting diodes (LEDs) disposed over the substrate;

applying an underfill layer after the one or more LEDs are disposed over the substrate, wherein the underfill layer is disposed at least partially between the one or more LEDs and the substrate; and

controlling light output from the one or more LEDs by selectively applying a reflective underfill layer to increase light output from the one or more LEDs or applying a non-reflective or dark underfill layer to decrease light output from the one or more LEDs.

6. A light emitting diode (LED) apparatus, comprising:

a substrate;

one or more light emitting diodes (LEDs); and

a powder-coated material disposed over the substrate.

7. The LED apparatus of claim 6, wherein the powder-coated material is also disposed over the one or more LEDs.

8. The LED apparatus of claim 6, wherein the powder-coated material is an encapsulant material.

9. The LED apparatus of claim 8, wherein the encapsulant material comprises epoxy, epoxy-polyester hybrid, aliphatic urethane, TGIC polyester, non-TGIC polyester, silicone, silicon-modified polyester, or combinations thereof.

10. The LED apparatus of claim 8, wherein a filler material such as a mineral or silica is added to the encapsulant material.

11. The LED apparatus of claim 8, wherein the powder-coated material is less than 0.2 mm thick.

12. A light emitting diode (LED) apparatus, comprising:

a substrate;

one or more light emitting diodes (LEDs);

one or more light-transmissive layer disposed over the substrate and one or more LEDs; and

one or more dark layer disposed over the one or more light-transmissive layer,

wherein a region above the one or more LEDs is substantially or completely devoid of the one or more dark layer.

13. The LED apparatus of claim 12, wherein a region above the one or more LEDs is substantially or completely devoid of the one or more dark layer.

14. The LED apparatus of claim 12, wherein the one or more light transmissive is clear.

15. The LED apparatus of claim 12, wherein the one or more dark layer is black.

16. The LED apparatus of claim 13, wherein the region above the one or more LEDs is further devoid of the one or more light-transmissive layer.

17. The LED apparatus of claim 12, wherein the one or more light-transmissive layer is disposed at least partially under the one or more LEDs, between the one or more LEDs and the substrate.

18. The LED apparatus of claim 12, wherein a thickness of the one or more dark layer is in a range of about 0.01-0.2 mm.

19. The LED apparatus of claim 12, further comprising an intermediate reflective layer disposed between the one or more light-transmissive layer and the one or more dark layer.

20. The LED apparatus of claim 12, wherein any of the layers is a powder-coated material.

21. The LED apparatus of claim 20, wherein the one or more dark layer comprises epoxy, epoxy-polyester hybrid, aliphatic urethane, TGIC polyester, non-TGIC polyester, silicone, silicon-modified polyester, or combinations thereof.

22. The LED apparatus of claim 20, wherein any of the layers further comprises a filler material such as a mineral or silica.

23. The LED apparatus of claim 12, wherein any of the layers is adapted to be removed by grinding, buffing, lapping, and/or sanding.

24. The LED apparatus of claim 12, further comprising at least one additional layer disposed over the one or more dark layer and the exposed portion of the one or more clear layer.

25. The LED apparatus of claim 12, further comprising opaque sidewalls.

26. The LED apparatus of claim 12, wherein at least one of the one or more LEDs is a wire-bonded LED.

27. The LED apparatus of claim 12, comprising a plurality of LEDs,

wherein the plurality of LEDs comprise at least one wirebonded LED and at least one non-wirebonded LED.

28. The LED apparatus of claim 26, wherein the at least one non-wirebonded LED has a thickness that is greater than a thickness of the at least one wirebonded LED.

29. The LED apparatus of claim 27, wherein the plurality of LEDs comprises LEDs of different thicknesses, and the LEDs are disposed on the substrate such that top surfaces of the LEDs are substantially coplanar.

30. The LED apparatus of claim 27, wherein the LEDs are disposed on electrical traces of different thicknesses.

31. A method of producing a panel of light emitting diodes (LEDs), the method comprising:

providing a substrate with at least one LED disposed over the substrate;

applying one or more light-transmissive layer over the at least one LED;

applying one or more dark layer over the light-transmissive layer; and

removing at least a portion of the layers in a region above the at least one LED to expose at least a portion of the one or more light-transmissive layer.

32. The method of claim 31, further comprising applying an intermediate reflective layer between applying the one or more light-transmissive layer and applying the one or more dark layer.

33. The method of claim 32, further comprising using a mechanical stop, a chip position, or time to control extent of removal of the layers.

34. The method of claim 31, further comprising applying an additional top layer after removing at least a portion of the layers.

35. The method of claim 34, further comprising lapping or buffing the additional top layer to modify the level of gloss.

36. The method of claim 32, further comprising providing opaque sidewalls.

37. The method of claim 36, wherein providing the opaque sidewalls comprises sawing one or move groove through the layers and applying opaque material in the groove.

38. The method of claim 36, wherein providing the opaque sidewalls further comprises sawing one or move groove.

39. A method of encapsulating a light emitting diode (LED) device, the method comprising:

providing a substrate with at least one LED disposed over the substrate; and

powder-coating the substrate and/or the LED with a powder using a powder spray or an electrostatic powder-coating process.

40. The method of claim 39, wherein the powder material comprises epoxy, epoxy-polyester hybrid, aliphatic urethane, TGIC polyester, non-TGIC polyester, silicone, silicone-modified polyester, or combinations thereof.

41. The method according to claim 39, further comprising adding filler material such as a mineral or silica to the powder material.