Method of making light emitting device with silicon-containing encapsulant

• US 20060105481A1
• Filed: 10/17/2005
• Published: 05/18/2006
• Est. Priority Date: 11/18/2004
• Status: Active Grant

• Current Assignee: 3M Innovative Properties Company (3M Company)
• Original Assignee: 3M Innovative Properties Company (3M Company)
• Inventors: Ouderkirk, Andrew J., Leatherdale, Catherine A., Thompson, D. Scott, Boardman, Larry D.
• Granted Patent: US 7,314,770 B2
• Time in Patent Office: Days
• US Class Current: 438/22
• CPC Class Codes: C08G 77/12 containing silicon bound to hydrogen C08G77/045 takes precedence
• CPC Class Codes: C08G 77/20 containing silicon bound to unsaturated aliphatic groups C08G77/045 takes precedence
• CPC Class Codes: C08G 77/70 Siloxanes defined by use of the MDTQ nomenclature
• CPC Class Codes: C08L 83/00 Compositions of macromolecular compounds obtained by reactions forming in the main chain of the macromolecule a linkage containing silicon with or without sulfur, nitrogen, oxygen or carbon only; Compositions of derivatives of such polymers
• CPC Class Codes: C08L 83/04 Polysiloxanes
• CPC Class Codes: H01L 2224/45144 Gold (Au) as principal constituent
• CPC Class Codes: H01L 2224/48091 Arched
• CPC Class Codes: H01L 2224/48247 connecting the wire to a bond pad of the item
• 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 2924/181 Encapsulation
• CPC Class Codes: H01L 33/56 Materials, e.g. epoxy or silicone resin

Abstract

A method of making a light emitting device is disclosed. The method includes the steps of providing a light emitting diode and forming an encapsulant in contact with the light emitting diode; wherein forming the encapsulant includes contacting the light emitting diode with a photopolymerizable composition consisting of a silicon-containing resin and a metal-containing catalyst, wherein the silicon-containing resin consists of silicon-bonded hydrogen and aliphatic unsaturation, and applying actinic radiation having a wavelength of 700 nm or less to initiate hydrosilylation within the silicon-containing resin.

Claims

1. A method of making a light emitting device, the method comprising the steps of:

providing a light emitting diode; and

forming an encapsulant in contact with the light emitting diode, wherein forming the encapsulant comprises;

contacting the light emitting diode with a photopolymerizable composition comprising a silicon-containing resin and a metal-containing catalyst, wherein the silicon-containing resin comprises silicon-bonded hydrogen and aliphatic unsaturation; and

applying actinic radiation having a wavelength of 700 nm or less to initiate hydrosilylation within the silicon-containing resin.

2. The method of claim 1 wherein the silicon-bonded hydrogen and the aliphatic unsaturation are present in the same molecule.

3. The method of claim 1 wherein the silicon-bonded hydrogen and the aliphatic unsaturation are present in different molecules.

4. The method of claim 1 wherein at least 5 mole percent of the aliphatic unsaturation is consumed in a hydrosilylation reaction.

5. The method of claim 1 wherein at least 60 mole percent of the aliphatic unsaturation is consumed in a hydrosilylation reaction.

6. The method of claim 5 wherein the hydrosilylation reaction occurs in less than 30 minutes.

7. The method of claim 6 wherein the hydrosilylation reaction occurs in less than 10 minutes.

8. The method of claim 7 wherein the hydrosilylation reaction occurs in less than 5 minutes.

9. The method of claim 8 wherein the hydrosilylation reaction occurs in less than 1 minute.

10. The method of claim 9 wherein the hydrosilylation reaction occurs in less than 10 seconds.

11. The method of claim 1 wherein applying actinic radiation comprises activating the light emitting diode.

12. The method of claim 1 wherein applying actinic radiation comprises applying actinic radiation at a temperature of less than 120°

C.

13. The method of claim 12 wherein applying actinic radiation comprises applying actinic radiation at a temperature of less than 60°

C.

14. The method of claim 13 wherein applying actinic radiation comprises applying actinic radiation at a temperature of 25°

C. or less.

15. The method of claim 1 wherein the metal-containing catalyst comprises platinum.

16. The method of claim 15 wherein the metal-containing catalyst is selected from the group consisting of Pt(II) β

-diketonate complexes, (η

⁵-cyclopentadienyl)tri(σ

-aliphatic)platinum complexes, and C_7-20-aromatic substituted (η

⁵-cyclopentadienyl)tri(σ

-aliphatic)platinum complexes.

17. The method of claim 1 wherein the actinic radiation has a wavelength of 600 nm or less.

18. The method of claim 17 wherein the actinic radiation has a wavelength of from 200 to 600 nm.

19. The method of claim 18 wherein the actinic radiation has a wavelength of from 250 to 500 nm.

20. The method of claim 1 wherein the encapsulant is a liquid, gel, elastomer, or non-elastic solid.

21. The method of claim 1 wherein the encapsulant has a refractive index of at least 1.34.

22. The method of claim 1 wherein the encapsulant has a refractive index of at least 1.50.

23. The method of claim 1 wherein the photopolymerizable composition comprises an organosiloxane.

24. The method of claim 2 wherein the photopolymerizable composition comprises an organosiloxane.

25. The method of claim 1 wherein the photopolymerizable composition comprises a first organosiloxane having silicon-bonded hydrogen and a second organosiloxane having aliphatic unsaturation.

26. The method of claim 25 wherein the photopolymerizable material comprises an organosiloxane comprising units of the formula:

R¹_aR²_bSiO_(4-a-b)/2

wherein;

R¹ is a monovalent, straight-chained, branched or cyclic, unsubstituted or substituted, hydrocarbon group that is free of aliphatic unsaturation and has from 1 to 18 carbon atoms;

R² is a monovalent hydrocarbon group having aliphatic unsaturation and from 2 to 10 carbon atoms;

a is 0, 1, 2, or 3;

b is 0, 1, 2, or 3; and

the sum a+b is 0, 1, 2, or 3;

with the proviso that there is on average at least one R¹ present per molecule.

27. The method of claim 26 wherein at least 90 mole percent of the R¹ groups are methyl.

28. The method of claim 26 wherein at least 20 mole percent of the R¹ groups are aryl, aralkyl, alkaryl, or combinations thereof.

29. The method of claim 28 wherein the R¹ groups are phenyl.

30. The method of claim 26 wherein the R² groups are vinyl or 5-hexenyl.

31. The method of claim 25 wherein the photopolymerizable material comprises an organosiloxane comprising units of the formula:

R¹_aH_cSiO_(4-a-c)/2

wherein;

R¹ is a monovalent, straight-chained, branched or cyclic, unsubstituted or substituted, hydrocarbon group that is free of aliphatic unsaturation and has from 1 to 18 carbon atoms;

a is 0, 1, 2, or 3;

c is 0, 1, or 2; and

the sum of a+c is 0, 1, 2, or 3;

with the proviso that there is on average at least one silicon-bonded hydrogen present per molecule.

32. The method of claim 31 wherein at least 90 mole percent of the R¹ groups are methyl.

33. The method of claim 31 wherein at least 20 mole percent of the R¹ groups are aryl, aralkyl, alkaryl, or combinations thereof.

34. The method of claim 33 wherein the R¹ groups are phenyl.

35. The method of claim 1 wherein the photopolymerizable material comprises an organosiloxane comprising the formulae:

R¹_aR²_bSiO_(4-a-b)/2 and R¹_aH_cSiO_(4-a-c)/2

wherein;

R¹ is a monovalent, straight-chained, branched or cyclic, unsubstituted or substituted hydrocarbon group that is free of aliphatic unsaturation and has from 1 to 18 carbon atoms;

R² is a monovalent hydrocarbon group having aliphatic unsaturation and from 2 to 10 carbon atoms;

a is 0, 1, 2, or 3;

b is 0, 1, 2, or 3;

c is 0, 1, or 2;

the sum a+b is 0, 1, 2, or 3; and

the sum of a+c is 0, 1, 2, or 3;

with the proviso that there is on average at least one silicon-bonded hydrogen and at least one R² group present per molecule.

36. The method of claim 35 wherein at least 90 mole percent of the R¹ groups are methyl.

37. The method of claim 35 wherein at least 20 mole percent of the R¹ groups are aryl, aralkyl, alkaryl, or combinations thereof.

38. The method of claim 37 wherein the R¹ groups are phenyl.

39. The method of claim 35 wherein the R² groups are vinyl or 5-hexenyl.

40. The method of claim 1 wherein the silicon-bonded hydrogen and the aliphatic unsaturation are present in a molar ratio of from 0.5 to 10.0.

41. The method of claim 40 wherein the silicon-bonded hydrogen and the aliphatic unsaturation are present in a molar ratio of from 0.8 to 4.0.

42. The method of claim 41 wherein the silicon-bonded hydrogen and the aliphatic unsaturation are present in a molar ratio of from 1.0 to 3.0.

43. The method of claim 1 wherein the photopolymerizable material comprises one or more additives selected from the group consisting of nonabsorbing metal oxide particles, semiconductor particles, phosphors, sensitizers, antioxidants, pigments, photoinitiators, catalyst inhibitors, and combinations thereof.

44. A light emitting device prepared using the method of claim 1.

45. The method of claim 12, wherein forming the encapsulant further comprises the step of heating at less than 150°

C.

46. The method of claim 45, wherein heating is at less than 100°

C.

47. The method of claim 46, wherein heating is at less than 60°

C.

48. A light emitting device comprising a light emitting diode and a photopolymerizable composition comprising a silicon-containing resin and a metal-containing catalyst, wherein the silicon-containing resin comprises silicon-bonded hydrogen and aliphatic unsaturation.

49. The light emitting device of claim 48, wherein the metal-containing catalyst comprises platinum.

50. The light emitting device of claim 48, wherein the photopolymerizable composition is at a temperature of from about 30°

C. to about 120°

C.

51. The light emitting device of claim 50, wherein the metal-containing catalyst comprises platinum.