Light emitting device provided with a submount assembly for improved thermal dissipation

• US 7,391,153 B2
• Filed: 07/15/2004
• Issued: 06/24/2008
• Est. Priority Date: 07/17/2003
• Status: Active Grant

• Current Assignee: Toyoda Gosei Company Limited (Toyota Motor Corporation)
• Original Assignee: Toyoda Gosei Company Limited (Toyota Motor Corporation)
• Inventors: Wada, Satoshi, Suehiro, Yoshinobu, Tohmon, Ryoichi
• Primary Examiner(s): Santiago; Mariceli
• Application Number:
  US10/891,422
• Publication Number:
  US 20060012299A1
• Time in Patent Office: 1,440 Days
• Field of Search: 313498-512, 313/501, 257 98-103, 362/555, 362/800
• US Class Current: 313/512
• CPC Class Codes: F21K 9/00 Light sources using semiconductor devices as light-generating elements, e.g. using light-emitting diodes [LED] or lasers
• 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 2224/48257 connecting the wire to a die pad of the item
• CPC Class Codes: H01L 2224/8592 Applying permanent coating, e.g. protective coating
• CPC Class Codes: H01L 25/0753 the devices being arranged next to each other
• 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 33/20 with a particular shape, e.g. curved or truncated substrate
• CPC Class Codes: H01L 33/56 Materials, e.g. epoxy or silicone resin
• CPC Class Codes: H01L 33/62 Arrangements for conducting electric current to or from the semiconductor body, e.g. lead-frames, wire-bonds or solder balls
• CPC Class Codes: H01L 33/642 characterized by the shape
• CPC Class Codes: Y10S 362/80 Light emitting diode

Abstract

A light emitting device has: a light emitting element; a lead that is electrically connected to the light emitting element at its one end and serves as a terminal to supply a power source to the light emitting element; a metal base that the light emitting element is mounted thereon and radiates heat of the light emitting element; and a sealing member that is of transparent resin or glass and covers the light emitting element. The lead is secured to the metal base by a heat-resisting insulating member with a thermal expansion coefficient nearly equal to that of the metal base.

Claims

1. A light emitting device, comprising:

a light emitting element comprising a light emitting layer to emit light with a predetermined wavelength; and

a sealing portion that seals the light emitting element, the sealing portion comprising a glass,

wherein the light emitting element comprises a substrate comprising a stress reducing portion to reduce an internal stress in the sealing portion, the stress reducing portion being formed on an opposite side to a side where the light emitting layer is formed,

the light emitting element is flip-chip mounted, and

the stress reducing portion comprises an oblique portion formed between a top surface and a side surface of the substrate, the top surface and the side surface being substantially orthogonal to each other.

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

the oblique portion comprises an obliquely-cut surface or a rounded surface.

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

a refractive index of the substrate is approximately equal to a refractive index of the light emitting layer.

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

the sealing portion comprises an optical shape to radiate the light in a predetermined direction.

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

the sealing portion is integrated with by hot pressing a composite glass of at least two glass layers stacked.

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

the composite glass includes a thin-film phosphor layer to be excited by the light between the at least two glass layers.

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

the composite glass includes a phosphor complex-contained glass layer to contain a phosphor complex to be excited by the light.

8. A light emitting device, comprising:

a light emitting element;

a lead that is electrically connected to the light emitting element at its one end and serves as a terminal to supply a power source to the light emitting element;

a metal base that the light emitting element is mounted thereon and radiates heat of the light emitting element; and

a sealing member that comprises a transparent resin or glass and covers the light emitting element,

wherein a part of the lead is disposed parallel to the metal base to sandwich a heat-resisting insulating member between the lead and the metal base, and

the heat-resisting insulating member has a thermal expansion coefficient nearly equal to that of the metal base.

9. The light emitting element according to claim 8 further comprising:

a submount that makes a connection to the light emitting element and the lead through an electrode or a wiring layer,

wherein the light emitting element is mounted on the metal base through the submount.

10. The light emitting element according to claim 8, wherein:

the heat-resisting insulating member comprises a glass, and

the lead comprises a metal plate.

11. The light emitting element according to claim 8, wherein:

the heat-resisting insulating member comprises a ceramics, and

the lead comprises a metal pattern formed on the heat-resisting insulating member.

12. The light emitting element according to claim 8 further comprising:

a metal reflection mirror portion that is stacked on the metal base or integrated with the metal base.

13. The light emitting element according to claim 8, wherein:

the metal base comprises a radiation fin.

14. The light emitting element according to claim 12, wherein:

at least one of the metal base and the metal reflection mirror comprises a radiation fin.

15. The light emitting element according to claim 8, wherein:

the metal base comprises a sheet heat sink.

16. A light emitting device, comprising:

an optical element;

a submount that the optical element is mounted thereon and comprises a thermal expansion coefficient nearly equal to that of the optical element;

a support member that comprises a hole into which the submount is inserted, and comprises a thermal expansion coefficient greater than that of the submount; and

a transparent sealing member that seals the optical element and is transparent to a targeted wavelength,

wherein the submount is disposed such that its surface to mount the optical element is exposed from the hole on the side of the sealing member, and is bonded to the support member and the transparent sealing member to seal the optical element, and

the support member comprises ceramics.

17. The light emitting device according to claim 16, wherein:

the transparent sealing member comprises glass.

18. The light emitting device according to claim 16, wherein:

the support member comprises a thermal expansion coefficient nearly equal to that of the transparent sealing member.

19. The light emitting device according to claim 16, wherein:

the submount comprises a thermal conductivity coefficient of 100 or more W·

m<sup>−

1</sup>·

k<sup>−

1</sup>.

20. The light emitting device according to claim 16, wherein:

the submount comprises a convex shape in cross section that can be concave-convex fitted with the support member.

21. The light emitting device according to claim 16, wherein:

the submount comprises the surface to mount the optical element with an area nearly equal to that of the optical element.

22. The light emitting device according to claim 16, wherein:

the support member and the transparent sealing member comprise a thermal expansion coefficient of 10 to 20×

10<sup>−

6</sup>/°

C.

23. The light emitting device according to claim 16, wherein:

the support member comprises a glass-contained Al₂O₃.

24. The light emitting device according to claim 16, wherein:

the support member comprises a multilayer substrate that a wiring pattern is formed in its cross section.

25. The light emitting device according to claim 16, wherein:

the optical element comprises a light emitting element.

26. The light emitting device according to claim 25, wherein:

the light emitting element is flip-chip bonded.

27. The light emitting device according to claim 25, wherein:

the light emitting element comprises a face-up type light emitting element and is covered with a heat resisting material while being electrically connected with a wire.

28. The light emitting device according to claim 16, wherein:

the submount comprises a radiation portion at its bottom.