Encapsulant with index matched thixotropic agent

• US 10,147,853 B2
• Filed: 03/18/2011
• Issued: 12/04/2018
• Est. Priority Date: 03/18/2011
• Status: Active Grant

• Current Assignee: Creeled Incorporated
• Original Assignee: CREE Incorporated (Wolfspeed, Inc.)
• Inventors: Keller, Bernd, Lowes, Theodore
• Primary Examiner(s): Lee, Eugene
• Application Number:
  US13/051,894
• Publication Number:
  US 20120235190A1
• Time in Patent Office: 2,818 Days
• Field of Search: 257 98, 257100, 313512
• 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 33/56 Materials, e.g. epoxy or silicone resin

Abstract

Emitter packages are disclosed having a thixotropic agent or material, with the encapsulant exhibiting significant reduction of thixotropic agent scattering. The packages exhibit a corresponding reduction or elimination of encapsulant clouding and increased package emission efficiency. This allows for the thixotropic agents to be included in the encapsulant to alter certain properties (e.g. mechanical or thermal) while not significantly altering the optical properties of the encapsulant. One embodiment of a light emitting diode (LED) package according to the present invention comprises an LED chip with an encapsulant over the LED chip. The encapsulant has an encapsulant refractive index and also has a thixotropic material with a refractive index that is substantially the same as the encapsulant refractive index.

Claims

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

an LED chip;

an encapsulant over said LED chip, said encapsulant comprising a first portion over said LED chip and a second portion over said first portion, at least one of said portions comprising an associated encapsulant refractive index;

a meniscus feature, in which an outer edge of the meniscus feature defines an outer boundary of said first and second encapsulant portions; and

a thickening material within at least one of said first and second portions, said material comprising a composite of two or more materials at least one of which comprises an index of refraction lower than said encapsulant refractive index and at least one of which comprises a material with a refractive index higher than said encapsulant refractive index, wherein the concentrations of said two or more materials within said at least one of said first and second portions are such that the combination of the two or more materials results in a refractive index that approaches said associated encapsulant refractive index.

2. The LED package of claim 1, wherein said thickening material comprises a thixotropic material.

3. The LED package of claim 1, wherein said LED chip emits LED light that passes through said encapsulant, said encapsulant and thickening material combination being substantially non-scattering to said LED light.

4. The LED package of claim 1, wherein said thickening material comprises a refractive index that is plus or minus n=0.05 of the encapsulant refractive index.

5. The LED package of claim 1, wherein said thickening material comprises a refractive index that is plus or minus n=0.04 of the encapsulant refractive index.

6. The LED package of claim 1, wherein said thickening material comprises a refractive index that is plus or minus n=0.02 of the encapsulant refractive index.

7. The LED package of claim 1, wherein said thickening material comprises particles with a surface area greater than 100 meters squared per gram (m²/g).

8. The LED package of claim 1, wherein said thickening material comprises particles with a surface area greater than 300 meters squared per gram (m²/g).

9. The LED package of claim 1, wherein said thickening material comprises particles with a size less than 0.1 micrometers (μ

m).

10. The LED package of claim 1, wherein said thickening material comprises particles with a size less than 0.5 micrometers (μ

m).

11. The LED package of claim 1, wherein said encapsulant comprises a material with refractive index of n≈

1.51, and said thickening material comprising a refractive index of N≈

1.51, plus or minus 0.05.

12. The LED package of claim 1, wherein said thickening material comprises one or more oxides.

13. The LED package of claim 1, wherein said encapsulant comprises a polymer and said thickening material comprises one or more oxides.

14. The LED package of claim 1, wherein said encapsulant comprises silicone, and said thickening material comprises an aluminosilicate composite.

15. The LED package of claim 1, wherein said thickening material alters the mechanical properties of said encapsulant without substantially altering its optical properties.

16. The LED package of claim 1, wherein said thickening material alters the thermal properties of said encapsulant without substantially altering its optical properties.

17. The LED package of claim 1, wherein said thickening material alters the electrical properties of said encapsulant without substantially altering its optical properties.

18. The LED package of claim 1, further comprising a submount, said LED mounted to said submount.

19. The LED package of claim 18, wherein said composite thixotropic material has comprises silica and alumina.

20. A light emitting diode (LED) package, comprising:

an LED chip;

an encapsulant over said LED chip, said encapsulant comprising an encapsulant refractive index; and

a thickening material within the encapsulant, the thickening material comprising a composite of two or more oxide materials, said composite material comprising a refractive index that is within plus or minus n=0.05 of the encapsulant refractive index;

wherein said thickening material comprises particles with a surface area greater than 100 meters squared per gram (m²/g).

21. The LED package of claim 20, wherein said thickening material comprises a thixotropic material.