Optical bonding composition for LED light source

• US 8,013,345 B2
• Filed: 11/07/2007
• Issued: 09/06/2011
• Est. Priority Date: 11/20/2006
• Status: Active Grant

• Current Assignee: 3M Innovative Properties Company (3M Company)
• Original Assignee: 3M Innovative Properties Company (3M Company)
• Inventors: Barnes, Amy S., Thompson, D. Scott, Ballen, Todd A.
• Primary Examiner(s): LOEWE, ROBERT S
• Application Number:
  US12/514,626
• Publication Number:
  US 20100025711A1
• Time in Patent Office: 1,399 Days
• Field of Search: 257/79, 257/98, 257/100, 257/E33.001, 438/26, 438/29, 106/287.16
• US Class Current: 257/79
• CPC Class Codes: F21V 7/0091 using total internal reflection
• CPC Class Codes: F21Y 2115/10 Light-emitting diodes [LED]
• 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 33/58 Optical field-shaping elements

Abstract

An optical bonding composition and LED light source comprising the composition are disclosed, as well as a method of making the LED light source. The LED light source may comprise: an LED die; an optical element optically coupled to the LED die; and a bonding layer comprising an amorphous organopolysiloxane network, the organopolysiloxane network comprising a silsesquioxane portion derived from (R¹SiO_1.5)_n wherein R¹ is an organic group and n is an integer of at least 10; the bonding layer bonding the LED die and the optical element together. Efficiency of the LED light source may be increased when using an optical extractor as the optical element.

Claims

1. An LED light source comprising:

an LED die;

an optical element optically coupled to the LED die; and

a bonding layer comprising an amorphous organopolysiloxane network, the organopolysiloxane network comprising a silsesquioxane portion derived from

(R¹SiO_1.5)_n

and a portion derived from D-units, the D-units having the formula (R²)₂Si(OR³)₂ wherein R¹, R² and R³ are organic groups

and n is an integer of at least 10;

the bonding layer bonding the LED die and the optical element together.

2. The LED light source of claim 1, wherein n is an integer of at least 20.

3. The LED light source of claim 1, wherein R¹ is an alkyl, alkylaryl, arylalkyl, or aryl group.

4. The LED light source of claim 1, wherein R¹ is a methyl, ethyl, propyl, phenyl or naphthyl group.

5. The LED light source of claim 1, the bonding layer comprising at least about 5% by weight of the silsesquioxane portion.

6. The LED light source of claim 1, the bonding layer comprising at least about 20% by weight of the silsesquioxane portion.

7. The LED light source of claim 1, the bonding layer comprising at least about 40% by weight of the silsesquioxane portion.

8. The LED light source of claim 1, wherein R¹═

R².

9. The LED light source of claim 1, wherein R² is methyl or phenyl.

10. The LED light source of claim 1, the bonding layer further comprising surface-modified metal oxide nanoparticles.

11. The LED light source of claim 10, the surface-modified metal oxide nanoparticles comprising metal oxide nanoparticles selected from the group consisting of zirconium oxide, titanium oxide, zinc oxide, tantalum oxide, niobium oxide, lanthanum oxide, strontium oxide, yttrium oxide, hafnium oxide, tin oxide, antimony oxide, and combinations thereof.

12. The LED light source of claim 10, the surface-modified metal oxide nanoparticles comprising mixed metal oxide nanoparticles of at least two metal oxides selected from the group consisting of silicon oxide, aluminum oxide, zirconium oxide, titanium oxide, zinc oxide, tantalum oxide, niobium oxide, lanthanum oxide, strontium oxide, yttrium oxide, hafnium oxide, tin oxide, antimony oxide, and combinations thereof.

13. The LED light source of claim 12, the mixed metal oxide nanoparticles comprising silicon oxide and zirconium oxide.

14. The LED light source of claim 12, the mixed metal oxide nanoparticles comprising silicon oxide and titanium oxide.

15. The LED light source of claim 12, the mixed metal oxide nanoparticles comprising silicon oxide, zirconium oxide, and titanium oxide.

16. The LED light source of claim 10, the surface-modified metal oxide nanoparticles comprising crystalline zirconium oxide nanoparticles having a refractive index of greater than about 1.8.

17. The LED light source of claim 10, the surface-modified metal oxide nanoparticles comprising crystalline titanium oxide nanoparticles having a refractive index of greater than about 2.0.

18. The LED light source of claim 10, the surface-modified metal oxide nanoparticles being surface-modified with a surface-modifier, the surface-modifier comprising a carboxylic acid, a phosphonic acid, an alkoxysilane, or a combination or mixture thereof.

19. The LED light source of claim 18, the carboxylic acid comprising a polyethyleneglycol carboxylic acid.

20. The LED light source of claim 10, the bonding layer comprising from about 40 to about 95% by weight of the surface-modified metal oxide nanoparticles.

21. The LED light source of claim 1, the LED die comprising a light emitting layer having a refractive index of greater than 1.9, and the bonding layer having a thickness of from about 50 nm to about 100 microns.

22. The LED light source of claim 1, the LED die comprising a light emitting layer having a refractive index of less than or equal to 1.9, and the bonding layer having a thickness of from greater than about 5 nm to about 300 nm.

23. The LED light source of claim 1, wherein the LED die comprises a light emitting surface, the optical element comprises a light input surface, and the bonding layer bonds the light emitting surface and the light input surface together.

24. The LED light source of claim 1, the optical element having a refractive index of at least about 2.0.

25. The LED light source of claim 1, the optical element comprising an optical glass having a refractive index of at least about 1.7.

26. The LED light source of claim 1, the optical element comprising a diverging or converging extractor.

27. A method of making an LED light source, the method comprising:

a) providing an LED die;

b) providing an optical element;

c) providing an optical bonding composition comprising a silsesquioxane having the formula (R¹SiO_1.5)_n(OR⁴)_n+2 and a dialkoxysilane having the formula (R²)₂Si(OR³)₂, wherein R¹ to R⁴ are organic groups and n is an integer of at least 5; and

d) bonding the LED die and the optical element together by contacting the LED die and the optical element with the optical bonding composition.

28. The method of claim 27, wherein an assembly is formed from bonding the LED die and the optical element together, and the method further comprises heating the assembly.

29. The method of claim 27, the optical bonding composition further comprising surface-modified metal oxide nanoparticles.

30. The LED light source of claim 29, the surface-modified metal oxide nanoparticles comprising crystalline zirconium oxide nanoparticles having a refractive index of greater than about 1.8.