OPTICAL BONDING COMPOSITION FOR LED LIGHT SOURCE

• US 20100025711A1
• Filed: 11/07/2007
• Published: 02/04/2010
• 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: Ballen, Todd A., Thompson, D. Scott, Barnes, Amy S.
• Granted Patent: US 8,013,345 B2
• Time in Patent Office: Days
• US Class Current: 257/98
• 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

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.

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, the amorphous organopolysiloxane network being derived essentially from D-units, the D-units comprising:

(R²)₂Si(OR³)₂.

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

R².

10. The LED light source of claim 8, wherein R² is methyl or phenyl.

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

12. The LED light source of claim 11, 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.

13. The LED light source of claim 11, 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.

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

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

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

17. The LED light source of claim 11, the surface-modified metal oxide nanoparticles comprising crystalline zirconium oxide nanoparticles having a refractive index of greater than about 1.8.

18. The LED light source of claim 11, the surface-modified metal oxide nanoparticles comprising crystalline titanium oxide nanoparticles having a refractive index of greater than about 2.0.

19. The LED light source of claim 11, 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.

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

21. The LED light source of claim 11, the bonding layer comprising from about 40 to about 95% by weight of the surface-modified metal oxide nanoparticles.

22. 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 um.

23. 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.

24. 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.

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

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

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

28. 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.

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

30. The method of claim 28, the optical bonding composition further comprising surface-modified metal oxide nanoparticles.

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

32. An optical bonding composition comprising:

surface-modified metal oxide nanoparticles;

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.

33. The optical bonding composition of claim 32, 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.

34. The optical bonding composition of claim 32, 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.

35. The optical bonding composition of claim 32, the surface-modified metal oxide nanoparticles comprising crystalline zirconium oxide nanoparticles having a refractive index of greater than about 1.8.

36. The optical bonding composition of claim 35, wherein the surface-modified metal oxide nanoparticles are present in an amount greater than one-half the source of the organopolysiloxane precursors on a weight basis.

37. The optical bonding composition of claim 32, further comprising an acid.

38. An LED light source comprising:

an LED die; and

an encapsulant in contact with and encapsulating the LED die, the encapsulant comprising the optical bonding composition of claim 32.

39. The LED light source of claim 38, the encapsulant having a refractive index of greater than about 1.6.

40. The LED light source of claim 38, wherein R¹ and R² are phenyl groups.

41. The LED light source of claim 38, wherein the surface-modified metal oxide nanoparticles comprise crystalline zirconium oxide nanoparticles having a refractive index of greater than about 1.8.

42. The LED light source of claim 38, the surface-modified metal oxide nanoparticles being surface-modified with a surface-modifier, the surface-modifier comprising a polyethyleneglycol carboxylic acid.

43. An LED light source comprising:

an LED die; and

an encapsulant in contact with and encapsulating the LED die, the encapsulant 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.

44. The LED light source of claim 43, the encapsulant comprising surface-modified metal oxide nanoparticles, the surface-modified metal oxide nanoparticles comprising crystalline zirconium oxide nanoparticles having a refractive index of greater than about 1.8.

45. The LED light source of claim 43, the amorphous organopolysiloxane network being derived essentially from D-units, the D-units comprising:

(R²)₂Si(OR³)₂.

46. The LED light source of claim 45, the encapsulant comprising surface-modified metal oxide nanoparticles, the surface-modified metal oxide nanoparticles comprising crystalline zirconium oxide nanoparticles having a refractive index of greater than about 1.8.

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

a) providing an LED die;

b) providing any of the optical bonding compositions described herein;

c) contacting the LED die with any of the compositions provided in b), thereby forming an assembly; and

d) optionally heating the assembly.