Method of making light emitting device with silicon-containing encapsulant

• US 7,427,523 B2
• Filed: 05/17/2006
• Issued: 09/23/2008
• Est. Priority Date: 11/18/2004
• Status: Expired due to Fees

• 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.
• Primary Examiner(s): Dang; Phuc T
• Application Number:
  US11/383,885
• Publication Number:
  US 20060199291A1
• Time in Patent Office: 860 Days
• Field of Search: 438/22, 438/26, 438/61, 438/63, 438/64, 438/118, 438/124, 257/79, 257/82, 257/103
• US Class Current: 438/22
• CPC Class Codes: H01L 2224/45144 Gold (Au) as principal constituent
• CPC Class Codes: H01L 2224/48091 Arched
• CPC Class Codes: H01L 23/293 Organic, e.g. plastic
• 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 2924/00014 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 33/52 Encapsulations
• 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 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 comprising a silicon-containing resin, a metal-containing catalyst, and surface treated particles, the silicon-containing resin comprises silicon-bonded hydrogen and aliphatic unsaturation, the surface treated particles comprising nonabsorbing metal oxide particles, semiconductor particles, or combinations thereof, 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:

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, a metal-containing catalyst, and surface treated particles, the silicon-containing resin comprises silicon-bonded hydrogen and aliphatic unsaturation, the surface treated particles comprising nonabsorbing metal oxide particles, semiconductor particles, or combinations thereof; 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, the nonabsorbing metal oxide particles comprising Al₂O₃, ZrO₂, TiO₂, V₂O₅, ZnO, SnO₂, ZnS, SiO₂, or mixtures thereof.

3. The method of claim 1, the semiconductor particles comprising ZnS, CdS or GaN.

4. The method of claim 1, the surface treated particles comprising a thin surface treatment of SiO₂.

5. The method of claim 1, the surface treated particles present in an amount of at least 45 wt-%, based on the total weight of the encapsulant.

6. The method of claim 1, the surface treated particles having an average particle size of from 10 nanometers to 100 nanometers.

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

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

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

10. The method of claim 1 wherein applying actinic radiation comprises applying actinic radiation at a temperature of less than 60°

C.

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

12. The method of claim 11 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.

13. The method of claim 1 wherein the silicon containing resin 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 R² present per molecule.

14. The method of claim 1 wherein the silicon containing resin 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.

15. The method of claim 1 wherein the silicon-bonded hydrogen and the aliphatic unsaturation are present in a molar ratio of from 1.0 to 3.0.

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

17. The method of claim 1 wherein the surface treated particles comprise particles surface treated with silanes, siloxanes, carboxylic acids, phosphonic acids, zirconates, or titanates.

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