Light emitting device with multilayer silicon-containing encapsulant

• US 9,308,680 B2
• Filed: 02/02/2010
• Issued: 04/12/2016
• Est. Priority Date: 05/17/2006
• Status: Expired due to Fees

• Current Assignee: 3M Innovative Properties Company (3M Company)
• Original Assignee: 3M Innovative Properties Company (3M Company)
• Inventors: Thompson, D. Scott, Boardman, Larry D., Leatherdale, Catherine A.
• Primary Examiner(s): Tsai, H
• Application Number:
  US12/698,251
• Publication Number:
  US 20100133574A1
• Time in Patent Office: 2,261 Days
• Field of Search: 257 79-100, 257/E25.032
• US Class Current: 1/1
• 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 light emitting device that includes a light emitting diode and a multilayer encapsulant is disclosed. The multilayer encapsulant includes a first encapsulant in contact with the light emitting diode and a photopolymerizable composition in contact with the first encapsulant. The first encapsulant may be a silicone gel, silicone gum, silicone fluid, organosiloxane, polysiloxane, polyimide, polyphosphazene, sol-gel composition, or another photopolymerizable composition. The photopolymerizable compositions include 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 can be applied to initiate hydrosilylation within the silicon-containing resins.

Claims

1. A light emitting device comprising:

a light emitting diode; and

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

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

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

wherein the first encapsulant has a refractive index greater than that of the photopolymerizable composition.

2. The light emitting device of claim 1, wherein the first encapsulant comprises an organosiloxane, and the organosilozane comprises a trimethylsilyloxy-terminated polydimenthysiloxane.

3. The light emitting device of claim 1, where in the silicon-bonded hydrogen and the aliphatic unsaturation are present in the same molecule.

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

5. The light emitting device of claim 1, wherein the photopolymerizable composition comprises organosiloxane.

6. The light emitting device of claim 1, wherein the photopolymerizable composition comprises 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 unstaturation 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 light emitting device of claim 6, wherein at least 20 mole percent of the R¹ groups are aryl, aralkyl, alkaryl, or combinations thereof.

8. The light emitting device of claim 1, wherein the photopolymerizable composition 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 unstaturation and has from 1 to 18 carbon atoms;

a is 0, 1, 2, or 3;

c is 0, 1, or 2; and

the sum 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 light emitting device of claim 8, wherein at least 90 mole percent of the R¹ groups are methyl.

10. The light emitting device of claim 1, wherein the silicon-bonded hydrogen and the aliphatic unsaturation are present in a molar ratio of from 1.5 to 10.0.

11. The light emitting device 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 light emitting device 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 light emitting device of claim 1, further comprising:

a wire bond connected to the light emitting diode;

wherein the first encapsulant encapsulates both the light emitting diode and the wire bond.