Method of making light emitting device with silicon-containing encapsulant

• US 20070092737A1
• Filed: 10/21/2005
• Published: 04/26/2007
• Est. Priority Date: 10/21/2005
• Status: Abandoned Application

• Current Assignee: 3M Innovative Properties Company (3M Company)
• Original Assignee: 3M Innovative Properties Company (3M Company)
• Inventors: Thompson, D., Ouderkirk, Andrew, Leatherdale, Catherine, Boardman, Larry
• Application Number:
  US11/255,712
• Publication Number:
  US 20070092737A1
• Time in Patent Office: Days
• US Class Current: 428/447
• 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: C08J 2383/04 Polysiloxanes
• CPC Class Codes: C08J 3/243 Two or more independent types of crosslinking for one or more polymers
• 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 2224/48091 Arched
• 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: Y10T 428/31663 As siloxane, silicone or silane

Abstract

A method of making a light emitting device is disclosed herein, the method including the steps of (A) providing a light emitting diode; and (B) contacting the light emitting diode with a photopolymerizable composition comprising: a silicon-containing resin comprising silicon-bonded hydrogen and aliphatic unsaturation; a first metal-containing catalyst that may be activated by actinic radiation; and a second metal-containing catalyst that may be activated by heat but not the actinic radiation; and (C) heating the photopolymerizable composition to a temperature of less than 150° C. to initiate hydrosilylation, thereby forming a first encapsulant.

Claims

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

(A) providing a light emitting diode; and

(B) contacting the light emitting diode with a photopolymerizable composition comprising;

a silicon-containing resin comprising silicon-bonded hydrogen and aliphatic unsaturation;

a first metal-containing catalyst that may be activated by actinic radiation; and

a second metal-containing catalyst that may be activated by heat but not the actinic radiation; and

(C) heating the photopolymerizable composition to a temperature of less than 150°

C. to initiate hydrosilylation, thereby forming a first encapsulant, wherein hydrosilylation comprises reaction between the silicon-bonded hydrogen and the aliphatic unsaturation.

2. The method of claim 1, further comprising the step of:

(D) applying actinic radiation at a wavelength of 700 nm or less to further initiate hydrosilylation within the silicon-containing resin, thereby forming a second encapsulant.

3. The method of claim 1 wherein hydrosilylation comprises reaction between the silicon-bonded hydrogen and at least 5 mole percent of the aliphatic unsaturation.

4. The method of claim 1 wherein hydrosilylation comprises reaction between the silicon-bonded hydrogen and at least 60 mole percent of the aliphatic unsaturation.

5. The method of claim 2 wherein hydrosilylation comprises reaction between the silicon-bonded hydrogen and at least 60 mole percent of the aliphatic unsaturation.

6. The method of claim 2 wherein reaction of the aliphatic unsaturation and the silicon-bonded hydrogen occurs in less than 30 minutes.

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

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

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

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

11. The method of claim 2 wherein applying actinic radiation comprises activating the light emitting diode.

12. The method of claim 2 wherein the first encapsulant is at a temperature of less than 120°

C.

13. The method of claim 12 wherein the first encapsulant is at a temperature of less than 60°

C.

14. The method of claim 13 wherein the first encapsulant is at a temperature of less than 25°

C.

15. The method of claim 1 wherein the photopolymerizable composition is heated to a temperature of less than 120°

C.

16. The method of claim 15 wherein the photopolymerizable composition is heated to a temperature of less than 60°

C.

17. The method of claim 16 wherein the photopolymerizable composition is heated to a temperature of less than 25°

C.

18. The method of claim 2, further comprising the step of:

(E) providing room temperature conditions to further initiate hydrosilylation, thereby forming a third encapsulant.

19. The method of claim 1 wherein the first metal-containing catalyst and/or the second metal-containing catalyst comprise platinum.

20. The method of claim 19 wherein the first 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.

21. The method of claim 19 wherein the second metal-containing catalyst comprises a platinum vinylsiloxane complex.

22. The method of claim 2 wherein the actinic radiation has a wavelength of 600 nm or less.

23. The method of claim 22 wherein the actinic radiation has at a wavelength of from 200 to 600 nm.

24. The method of claim 23 wherein the actinic radiation has at a wavelength of from 250 to 500 nm.

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

26. The method of claim 2 wherein the second encapsulant is a liquid, gel, elastomer, or non-elastic solid.

27. The method of claim 1 wherein the photopolymerizable composition has a refractive index of at least 1.34.

28. The method of claim 1 wherein the photopolymerizable composition has a refractive index of at least 1.50.

29. The method of claim 1 wherein the silicon-containing resin comprises one or more organosiloxanes.

30. The method of claim 29 wherein the one or more organosiloxanes comprises an organosiloxane having aliphatic unsaturation and silicon-bonded hydrogen in the same molecule.

31. The method of claim 29 wherein the one or more organosiloxanes comprises a first organosiloxane having aliphatic unsaturation and a second organosiloxane having silicon-bonded hydrogen.

32. The method of claim 31 wherein the first organosiloxane has the formula:

R¹_aR²_bSiO<sub>(4−

a−

b)/2</sub>

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 R² present per molecule.

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

34. The method of claim 32 wherein at least 20 mole percent of the R¹ groups are aryl, aralkyl, alkaryl, or combinations thereof.

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

36. The method of claim 32 wherein the R² groups are vinyl or 5-hexenyl.

37. The method of claim 31 wherein the second organosiloxane has the formula:

R¹_aH_cSiO<sub>(4−

a−

c)/2</sub>

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.

38. The method of claim 37 wherein at least 90 mole percent of the R¹ groups are methyl.

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

40. The method of claim 39 wherein the R¹ groups are phenyl.

41. The method of claim 30 wherein the photopolymerizable material comprises an organosiloxane comprising the formulae:

R¹_aR²_bSiO<sub>(4−

a−

b)/2</sub> and R¹_aH_cSiO<sub>(4−

a−

c)/2</sub>

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 is present per molecule.

42. The method of claim 41 wherein at least 90 mole percent of the R¹ groups are methyl.

43. The method of claim 41 wherein at least 20 mole percent of the R¹ groups are aryl, aralkyl, alkaryl, or combinations thereof.

44. The method of claim 43 wherein the R¹ groups are phenyl.

45. The method of claim 41 wherein the R² groups are vinyl or 5-hexenyl.

46. 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.

47. The method of claim 46 wherein the silicon-bonded hydrogen and the aliphatic unsaturation are present in a molar ratio of from 0.8 to 4.0.

48. The method of claim 47 wherein the silicon-bonded hydrogen and the aliphatic unsaturation are present in a molar ratio of from 1.0 to 3.0.

49. 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, adhesion promoters, and solvent.

50. The method of claim 1, further comprising the step of:

(D) simultaneously applying actinic radiation at a wavelength of 700 nm and heating to less than 150°

C. to further initiate hydrosilylation, thereby forming a second encapsulant.

51. A light emitting device prepared according to the method of claim 1.

52. A light emitting device prepared according to the method of claim 2.

53. A light emitting device prepared according to the method of claim 50.