Light emitting device and sealing material

• US 7,304,326 B2
• Filed: 02/04/2005
• Issued: 12/04/2007
• Est. Priority Date: 02/06/2004
• Status: Expired due to Fees

• Current Assignee: Toyoda Gosei Company Limited (Toyota Motor Corporation)
• Original Assignee: Toyoda Gosei Company Limited (Toyota Motor Corporation)
• Inventors: Kato, Hideaki, Suehiro, Yoshinobu, Takano, Seiji
• Primary Examiner(s): Jackson; Jerome
• Assistant Examiner(s): NGUYEN, JOSEPH H
• Application Number:
  US11/050,432
• Publication Number:
  US 20050173708A1
• Time in Patent Office: 1,033 Days
• Field of Search: 257/81, 257 98-100, 257/E33.058, 257/E33.059, 257/79
• US Class Current: 257/79
• CPC Class Codes: H01L 2224/32245 the item being metallic
• CPC Class Codes: H01L 2224/45144 Gold (Au) as principal constituent
• CPC Class Codes: H01L 2224/48247 connecting the wire to a bond pad of the item
• CPC Class Codes: H01L 2224/73265 Layer and wire connectors
• 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 2924/181 Encapsulation
• CPC Class Codes: H01L 33/56 Materials, e.g. epoxy or silicone resin

Abstract

A light emitting device has: a light emitting element; a conducting portion to supply power to the light emitting element; an element housing portion that houses the light emitting element therein; and a sealing material that seals the light emitting element housed in the element housing portion. The sealing material contains a transparent resin material and a transparent filler with a thermal expansion coefficient smaller than the transparent resin material, and the transparent filler has a refractive index nearly equal to the transparent resin material.

Claims

1. A light emitting device, comprising:

a light emitting element;

a conducting portion to supply power to the light emitting element;

an element housing portion that houses the light emitting element therein; and

a sealing material that seals the light emitting element housed in the element housing portion,

wherein the sealing material comprises a transparent resin material and a transparent filler with a thermal expansion coefficient smaller than the transparent resin material, said transparent filler having a volume ratio relative to said sealing material sufficient to preclude a thermal expansion sufficient to disrupt an electrical contact from said light emitting element, and

the transparent filler has a refractive index nearly equal to the refractive index of the transparent resin material so that the transparent filler does not significantly diffuse light emitted from said light emitting element.

2. The light emitting device according to claim 1, wherein:

the transparent filler comprises a material with a light transparency proof against light and heat generated from the light emitting element.

3. The light emitting device according to claim 1, wherein:

the element housing portion is cone-shaped.

4. The light emitting device according to claim 1, wherein:

the element housing portion comprises a ceramic material.

5. The light emitting device according to claim 1, wherein:

the sealing material comprises epoxy resin.

6. The light emitting device according to claim 1, wherein:

the sealing material comprises silicone.

7. The light emitting device of claim 6, wherein the refractive index of said transparent filler and said silicone is one of:

approximately 1.46, said transparent filler comprising an SiO₂ glass; and

approximately 1.52, said transparent filler comprising an SiO₂—

B₂O₃ glass.

8. The light emitting device according to claim 1, wherein:

the transparent filler comprises glass.

9. The light emitting device according to claim 1, wherein:

the sealing material comprises a phosphor.

10. The light emitting device according to claim 1, wherein:

the sealing material comprises two layers contacting each other,

a first layer of the two layers contacts the light emitting device,

a second layer of the two layers comprises a phosphor, and

the first layer comprises the transparent filler more than the second layer.

11. The light emitting device according to claim 1, wherein:

the sealing material comprises a region with a concentration of the transparent filler higher than the other region in the vicinity of the light emitting element, and

the concentration of the transparent filler is 50% or more in volume ratio.

12. The light emitting device of claim 1, wherein the concentration of the transparent filler is 50% or more in volume ratio.

13. The light emitting device of claim 1, wherein approximately 100 weight parts of said resin material is mixed with approximately 90 weight parts of said transparent filler.

14. A sealing material, comprising:

a transparent resin material to seal a solid-state element; and

a transparent filler,

wherein the transparent filler has a refractive index nearly equal to the transparent resin material so that said transparent filler does not significantly diffuse light emitted from said solid-state element, and

the transparent filler comprises a material with a light transparency proof against light and heat generated from the solid-state element and having a volume ratio relative to said transparent resin material sufficient to preclude a significant thermal expansion.

15. The sealing material according to claim 14, wherein:

the refractive index of the transparent filler is within ±

0.025 to the refractive index of the transparent resin material.

16. The sealing material according to claim 14, wherein:

the refractive index of the transparent filler is within ±

0.010 to the refractive index of the transparent resin material.

17. The sealing material according to claim 14, wherein:

the transparent filler comprises an average particle size of 10 to 100 micrometers.