Textured encapsulant surface in LED packages

• US 9,431,589 B2
• Filed: 12/14/2007
• Issued: 08/30/2016
• Est. Priority Date: 12/14/2007
• Status: Active Grant

• Current Assignee: Creeled Incorporated
• Original Assignee: CREE Incorporated (Wolfspeed, Inc.)
• Inventors: Loh, Ban P., You, Chenhua, Keller, Bernd, Cannon, Nathaniel O., Jackson, Mitch, Combs, Ernest W.
• Primary Examiner(s): FERNANDES, ERROL V
• Application Number:
  US12/002,429
• Publication Number:
  US 20090152573A1
• Time in Patent Office: 3,182 Days
• Field of Search: 257/729, 257/79, 257/82, 257/95, 257/98, 257/99, 313/512, 438/26, 362/231, 362/237, 362/373
• 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 2933/0091 Scattering means in or on the semiconductor body or semiconductor body package H01L33/22 takes precedence
• CPC Class Codes: H01L 33/54 having a particular shape

Abstract

A packaged LED device having a textured encapsulant that is conformal with a mount surface on which at least one LED chip is disposed. The textured encapsulant, which can be textured using an additive or subtractive process, is applied to the LED either prior to or during packaging. The encapsulant includes at least one textured surface from which light is emitted. The textured surface helps to reduce total internal reflection within the encapsulant, improving the extraction efficiency and the color temperature uniformity of the output profile. Several chips can be mounted beneath a single textured encapsulant. A mold having irregular surfaces can be used to form multiple encapsulants over many LEDs simultaneously.

Claims

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

first and second electrodes, said first electrode comprising a first top surface, said first and second electrodes are accessible for electrical connection from a side of the LED device opposite said primary emission surface;

a substrate comprising one or more vias, wherein said one or more vias provide a path for current to travel from said side of the LED device opposite said primary emission surface;

a plurality of LED chips entirely on said first top surface; and

an encapsulant disposed proximate to said mount surface, said encapsulant comprising a textured primary emission surface and at least one side emission surface;

wherein all of said first top surface is covered by said encapsulant and wherein said plurality of LED chips and said encapsulant are configured such that light can be emitted from said LED device from said at least one side emission surface;

wherein all of a top surface of said substrate adjacent to said encapsulant is covered by at least a portion of said encapsulant such that said encapsulant extends to the edges of said top surface of said substrate.

2. The LED device of claim 1, wherein said plurality of LED chips comprises LED chips emitting at least two different spectra of light.

3. The LED device of claim 2, said plurality of LED chips comprising LED chips emitting a red spectrum, LED chips emitting a green spectrum, and LED chips emitting a blue spectrum.

4. The LED device of claim 2, said plurality of LED chips comprising LED chips emitting a red spectrum and LED chips emitting a white spectrum.

5. The LED device of claim 2, said plurality of LED chips comprising LED chips emitting a blue spectrum and LED chips emitting a yellow spectrum.

6. The LED device of claim 2, wherein said plurality of LED chips is arranged in a substantially linear array.

7. The LED device of claim 1, wherein said first top surface comprises a reflective material.

8. The LED device of claim 7, wherein said reflective material forms a specular reflector.

9. The LED device of claim 7, wherein said reflective material forms a diffuse reflector.

10. The LED device of claim 7, wherein said reflective material forms a combination of specular and diffuse reflectors.

11. The LED device of claim 7, wherein said reflective material has light scattering properties.

12. The LED device of claim 1, wherein said textured primary emission surface comprises additive features.

13. The LED device of claim 1, wherein said textured primary emission surface comprises subtractive features.

14. The LED device of claim 1, wherein said encapsulant forms an interface with an ambient medium such that that index of refraction differential at said interface is at least 0.4.

15. The LED device of claim 1, wherein said textured primary emission surface has an average peak-to-valley roughness of 1-50 micrometers.

16. The LED device of claim 15, wherein said textured primary emission surface has an average peak-to-valley roughness ranging from 50-200 micrometers.

17. The LED device of claim 1, wherein said encapsulant comprises a wavelength conversion material.

18. The LED device of claim 1, wherein said encapsulant comprises phosphors.

19. The LED device of claim 1, wherein said encapsulant adheres directly to said LED chips and said first top surface.

20. The LED device of claim 1, wherein said encapsulant is attached to said LED chips with an adhesive epoxy.

21. The LED device of claim 1, wherein said textured emission surface has a patterned texture.

22. The LED device of claim 1, wherein said textured emission surface has a random texture.

23. The LED device of claim 1, said at least one side emission surface comprising a textured surface.

24. The LED device of claim 23, wherein said primary emission surface and said at least one side emission surface have different textures.

25. The LED device of claim 1, wherein said encapsulant has a thickness ranging from 70-200 micrometers.

26. The LED device of claim 1, wherein said first top surface is reflective.

27. The LED device of claim 1, wherein said second electrode comprises a second top surface;

and

wherein all of said second top surface is covered by said encapsulant.

28. The LED device of claim 27, wherein said first and second top surfaces are reflective.