Method of making a light emitting device

• US 8,523,626 B2
• Filed: 09/11/2007
• Issued: 09/03/2013
• Est. Priority Date: 09/12/2006
• Status: Active Grant

• Current Assignee: Toyoda Gosei Company Limited (Toyota Motor Corporation)
• Original Assignee: Toyoda Gosei Company Limited (Toyota Motor Corporation)
• Inventors: Suehiro, Yoshinobu
• Primary Examiner(s): Mai, Anh
• Assistant Examiner(s): Hanley, Britt D
• Application Number:
  US11/898,364
• Publication Number:
  US 20080074029A1
• Time in Patent Office: 2,184 Days
• Field of Search: 313/487, 313/503
• US Class Current: 445/23
• CPC Class Codes: H01L 2224/05001 Internal layers
• CPC Class Codes: H01L 2224/05023 the whole internal layer protruding from the surface
• CPC Class Codes: H01L 2224/05124 Aluminium [Al] as principal constituent
• CPC Class Codes: H01L 2224/05155 Nickel [Ni] as principal constituent
• CPC Class Codes: H01L 2224/05568 the whole external layer protruding from the surface
• CPC Class Codes: H01L 2224/05624 Aluminium [Al] as principal constituent
• CPC Class Codes: H01L 2224/05644 Gold [Au] as principal constituent
• CPC Class Codes: H01L 2224/06051 Bonding areas having different shapes
• CPC Class Codes: H01L 2224/06102 the bonding areas being at different heights
• CPC Class Codes: H01L 2224/16 of an individual bump connector
• CPC Class Codes: H01L 2224/16225 the item being non-metallic, e.g. insulating substrate with or without metallisation
• CPC Class Codes: H01L 24/97 the devices being connected to a common substrate, e.g. interposer, said common substrate being separable into individual assemblies after connecting
• CPC Class Codes: H01L 25/0753 the devices being arranged next to each other
• 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 2924/01019 Potassium [K]
• CPC Class Codes: H01L 2924/01078 Platinum [Pt]
• CPC Class Codes: H01L 2924/01079 Gold [Au]
• CPC Class Codes: H01L 2924/09701 Low temperature co-fired ceramic [LTCC]
• CPC Class Codes: H01L 2924/12041 LED
• CPC Class Codes: H01L 2924/15747 : Copper [Cu] as principal constituent
• CPC Class Codes: H01L 2924/15787 : Ceramics, e.g. crystalline carbides, nitrides or oxides
• CPC Class Codes: H01L 2924/351 : Thermal stress
• CPC Class Codes: H01L 33/40 : Materials therefor
• CPC Class Codes: H01L 33/501 : characterised by the materials, e.g. binder
• CPC Class Codes: H01L 33/56 : Materials, e.g. epoxy or silicone resin
• CPC Class Codes: H01L 33/60 : Reflective elements

Abstract

A light emitting device has a light emitting element, a mounting portion and a sealing part. On the mounting portion, the light emitting element is mounted and a circuit pattern is formed to supply power to the light emitting element. The sealing part is formed on the mounting portion, sealing the light emitting element, and formed of a glass and a phosphor uniformly dispersed in the glass. The phosphor is adapted to emit a wavelength-converted light by being excited by a light emitted from the light emitting element.

Claims

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

mounting a light emitting element on a mounting portion;

forming a phosphor layer near the mounting portion of the light emitting element;

mixing a powder glass and a powder phosphor to produce a mixed powder such that the powder phosphor is dispersed in the powder glass;

melting the mixed powder while reducing a volume of the mixed powder to produce a melt and then solidifying the melt to produce a phosphor dispersed glass; and

slicing the phosphor dispersed glass into plates so as to form a glass sealing part, each of the plates having a thickness according to a thickness of the glass sealing part prior to bonding;

bonding the glass sealing part to the mounting portion with the light emitting element mounted thereon to seal the light emitting element,

wherein the bonding is conducted by hot pressing, and

wherein the bonding is conducted such that a surface of the glass sealing part substantially parallel with a slicing direction of the slicing is bonded onto a substantially planar surface of the mounting portion.

2. The method according to claim 1, further comprising:

forming the phosphor dispersed glass into a plate glass,

wherein the bonding is conducted such that the plate glass is bonded to the mounting portion.

4. The method according to claim 1, further comprising:

forming a hollow portion between a portion of the light emitting element and the mounting portion, which remains devoid of the glass sealing part.

5. The method according to claim 1, wherein said mounting portion comprises a circuit pattern formed to supply power to the light emitting element, and the circuit pattern is surrounded by a junction of the glass sealing part and the mounting portion.

6. The method according to claim 1, wherein the mounting portion comprises a roughened surface, and the glass sealing part is bonded to the mounting portion at a junction and comprises a surface roughened along the roughened surface at the junction.

7. The method according to claim 1, wherein said mounting portion comprises a circuit pattern formed to supply power to the light emitting element and a transparent material, and the circuit pattern is formed adjacent to the light emitting element.

8. The method according to claim 1, wherein said mounting portion comprises a transparent polycrystalline alumina.

9. The method according to claim 1, wherein said mounting portion comprises a circuit pattern formed to supply power to the light emitting element, and the circuit pattern comprises a top layer comprising Ag.

10. The method according to claim 1, wherein said mounting portion comprises a circuit pattern formed to supply power to the light emitting element, the light emitting element comprises an emission wavelength less than 550 nm, the circuit pattern comprises a top layer comprising Au, and the phosphor emits a light with a wavelength not less than 550 nm by being excited by the light emitted from the light emitting element.

11. The method according to claim 1, wherein said light emitting element emits a blue light, and the phosphor emits a yellow light by being excited by the blue light.

12. The method according to claim 1, wherein said light emitting element emits an ultraviolet light, and the phosphor comprises a blue phosphor to emit a blue light by being excited by the ultraviolet light, a green phosphor to emit a green light by being excited by the ultraviolet light, and a red phosphor to emit a red light by being excited by the ultraviolet light.

13. The method according to claim 1, wherein said phosphor dispersed glass comprises a ZnO—

SiO₂R₂O based glass, where R comprises at least one of group I elements.

14. The method according to claim 1, wherein the phosphor layer formed near the mounting portion of the light emitting element is disposed on an entirety of an upper surface of the mounting portion of the light emitting element.

16. The method according to claim 1, wherein the mixed powder includes no binder.

3. A method of making a light emitting device comprising:

mounting a light emitting element on a mounting portion, the mounting portion including a wall portion formed at an outer side of the mounting portion;

forming a phosphor layer near the mounting portion of the light emitting element such that the phosphor layer extends to an edge of a circuit pattern disposed outside an area covered by the light emitting element, the circuit pattern formed so as to supply power to the light emitting element;

mixing a powder glass and a powder phosphor to produce a mixed powder such that the powder phosphor is dispersed in the powder glass;

arranging the mixed powder inside of the wall portion of the mounting portion such that the wall portion acts as a mold; and

melting the mixed powder within the wall portion while reducing a volume of the mixed powder to produce a melt in a decompression high-temperature atmosphere and then solidifying the melt to produce a phosphor dispersed glass on the mounting portion and to bond the phosphor dispersed glass to the mounting portion with the light emitting element mounted thereon to seal the light emitting element.

15. The method according to claim 3, wherein the phosphor layer formed near the mounting portion of the light emitting element is disposed on an entirety of an upper surface of the circuit pattern of the light emitting element.

19. The method according to claim 3, wherein the phosphor layer extends to an edge of the circuit pattern furthest from the light emitting element in a width direction of the circuit pattern.

20. The method according to claim 3, wherein a reflective pattern is formed on an inner surface of the wall portion.

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

mounting a light emitting element on a mounting portion;

forming a phosphor layer near the mounting portion of the light emitting element;

mixing a powder glass and a powder phosphor to produce a mixed powder such that the powder phosphor is dispersed in the powder glass;

melting the mixed powder while reducing a volume of the mixed powder to produce a melt and then solidifying the melt to produce a phosphor dispersed glass; and

bonding the phosphor dispersed glass to the mounting portion with the light emitting element mounted thereon to seal the light emitting element,

wherein the bonding is conducted by hot pressing,

wherein the phosphor dispersed glass is sliced prior to the bonding, and

wherein the phosphor dispersed glass bonded to the mounting portion comprises a plurality of phosphor dispersed glass layers.

18. The method according to claim 17, wherein the plurality of phosphor dispersed glass layers comprises a first phosphor dispersed glass layer disposed between a second phosphor dispersed glass layer and the light emitting element, and

wherein the second phosphor dispersed glass layer has a glass transition temperature higher than a glass transition temperature of the first phosphor dispersed glass layer.