Method of Making Light Emitting Device With Multilayer Silicon-Containing Encapsulant

• US 20070287208A1
• Filed: 04/30/2007
• Published: 12/13/2007
• Est. Priority Date: 05/17/2006
• Status: Active Grant

• Current Assignee: 3M Innovative Properties Company (3M Company)
• Original Assignee: 3M Innovative Properties Company (3M Company)
• Inventors: Leatherdale, Catherine A., Thompson, D. Scott, Boardman, Larry D.
• Granted Patent: US 7,655,486 B2
• Time in Patent Office: Days
• US Class Current: 438/26
• CPC Class Codes: B29C 2035/0833 using actinic light
• CPC Class Codes: B29C 45/14655 connected to or mounted on a carrier, e.g. lead frame
• CPC Class Codes: B29C 45/1671 with an insert
• CPC Class Codes: B29K 2083/00 Use of polymers having silicon, with or without sulfur, nitrogen, oxygen, or carbon only, in the main chain, as moulding material
• 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: C08G 77/80 Siloxanes having aromatic substituents, e.g. phenyl side groups
• CPC Class Codes: C08K 5/56 Organo-metallic compounds, i.e. organic compounds containing a metal-to-carbon bond
• CPC Class Codes: C08L 2312/06 by radiation
• 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 an LED light emitting device is disclosed. The method includes forming a multilayer encapsulant in contact with an LED by contacting the LED with a first encapsulant that is a silicone gel, silicone gum, silicone fluid, organosiloxane, polysiloxane, polyimide, polyphosphazene, sol-gel composition, or a first photopolymerizable composition, and then contacting the first encapsulant with a second photopolymerizable composition. Each photopolymerizable composition includes a silicon-containing resin and a metal-containing catalyst, the silicon-containing resin comprising silicon-bonded hydrogen and aliphatic unsaturation. Actinic radiation having a wavelength of 700 nm or less is applied to initiate hydrosilylation within the silicon-containing resins.

Claims

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

providing a light emitting diode; and

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

contacting the light emitting diode with a first encapsulant comprising a silicone gel, silicone gum, silicone fluid, organosiloxane, polysiloxane, polyimide, polyphosphazene, or sol-gel composition;

contacting the first encapsulant with a photopolymerizable composition comprising a silicon-containing resin and a metal-containing catalyst, the silicon-containing resin comprising 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 thereby forming a second encapsulant.

2. The method of claim 1, wherein the first encapsulant comprises an organosiloxane, and the organosiloxane comprises a trimethylsilyloxy-terminated polydimethylsiloxane.

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

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

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

6. The method of claim 1, wherein the photopolymerizable composition comprises an organosiloxane comprising units of 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.

7. The method of claim 6, wherein at least 20 mole percent of the R¹ groups are aryl, aralkyl, alkaryl, or combinations thereof.

8. The method of claim 1, wherein the photopolymerizable composition comprises an organosiloxane comprising units of 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.

9. The method of claim 8, wherein at least 90 mole percent of the R¹ groups are methyl.

10. 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.

11. The method of claim 1, 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.

12. 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.

13. The method of claim 1, wherein the first encapsulant has a refractive index greater than that of the second.

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

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

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

providing a light emitting diode; and

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

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

contacting the first photopolymerizable composition with a second photopolymerizable composition comprising a second silicon-containing resin and a second metal-containing catalyst, the second silicon-containing resin comprising silicon-bonded hydrogen and aliphatic unsaturation; and

applying actinic radiation having a wavelength of 700 nm or less to initiate hydrosilylation within the first and second silicon-containing resins thereby forming first and second encapsulants, respectively.

17. The method of claim 16, wherein the silicon-bonded hydrogen and the aliphatic unsaturation of the first silicon-containing resin are present in the same molecule.

18. The method of claim 16, wherein the silicon-bonded hydrogen and the aliphatic unsaturation of the first silicon-containing resin are present in different molecules.

19. The method of claim 16, wherein the first photopolymerizable composition comprises an organosiloxane.

20. The method of claim 16, wherein the first photopolymerizable material comprises an organosiloxane comprising units of 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.

21. The method of claim 20, wherein the R¹ groups are methyl, phenyl, or a combination thereof.

22. The method of claim 16, wherein the first photopolymerizable material comprises an organosiloxane comprising units of 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.

23. The method of claim 22, wherein the R¹ groups are methyl, phenyl, or a combination thereof.

24. The method of claim 16, wherein the silicon-bonded hydrogen and the aliphatic unsaturation of the first silicon-containing resin are present in a molar ratio of from 0.5 to 10.0.

25. The method of claim 16, 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.

26. The method of claim 16, wherein the first 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.

27. The method of claim 16, wherein the silicon-bonded hydrogen and the aliphatic unsaturation of the second silicon-containing resin are present in the same molecule.

28. The method of claim 16, wherein the silicon-bonded hydrogen and the aliphatic unsaturation of the second silicon-containing resin are present in different molecules.

29. The method of claim 16, wherein the second photopolymerizable composition comprises an organosiloxane.

30. The method of claim 16, wherein the second photopolymerizable material comprises an organosiloxane comprising units of 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.

31. The method of claim 30, wherein the R¹ groups are methyl, phenyl, or a combination thereof.

32. The method of claim 16, wherein the second photopolymerizable material comprises an organosiloxane comprising units of 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.

33. The method of claim 32, wherein the R¹ groups are methyl, phenyl, or a combination thereof.

34. The method of claim 16, wherein the silicon-bonded hydrogen and the aliphatic unsaturation of the second silicon-containing resin are present in a molar ratio of from 0.5 to 10.0.

35. The method of claim 16, wherein the second 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.

36. The method of claim 16, wherein the second 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.

37. The method of claim 16, wherein the first encapsulant has a refractive index greater than that of the second.

38. The method of claim 16, wherein applying actinic radiation comprises activating the light emitting diode.

39. A light emitting device prepared using the method of claim 16.

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

providing a light emitting diode; and

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

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

contacting the first photopolymerizable composition with a second photopolymerizable composition comprising a second silicon-containing resin and a second metal-containing catalyst, the second silicon-containing resin comprising silicon-bonded hydrogen and aliphatic unsaturation; and

contacting the second photopolymerizable composition with a third photopolymerizable composition comprising a third silicon-containing resin and a third metal-containing catalyst, the third silicon-containing resin comprising silicon-bonded hydrogen and aliphatic unsaturation; and

applying actinic radiation having a wavelength of 700 nm or less to initiate hydrosilylation within the first, second, and third silicon-containing resins thereby forming first, second, and third encapsulants, respectively.