Light-emitting diode lamp with low thermal resistance

• US 7,863,639 B2
• Filed: 04/12/2006
• Issued: 01/04/2011
• Est. Priority Date: 04/12/2006
• Status: Active Grant

• Current Assignee: Semileds Optoelectronics Company Limited (SemiLEDs Inc)
• Original Assignee: Semileds Optoelectronics Company Limited (SemiLEDs Inc)
• Inventors: Yen, Jui-Kang
• Primary Examiner(s): Vu, David
• Assistant Examiner(s): Taylor, Earl N
• Application Number:
  US11/279,530
• Publication Number:
  US 20070241363A1
• Time in Patent Office: 1,728 Days
• Field of Search: 257/99, 257/100, 257/703, 257/693, 257/E33.058, 257/E33.066, 257/E33.075
• US Class Current: 257/99
• CPC Class Codes: H01L 2224/32225 the item being non-metallic, e.g. insulating substrate with or without metallisation
• CPC Class Codes: H01L 2224/48227 connecting the wire to a bond pad of the item
• CPC Class Codes: H01L 2224/73265 Layer and wire connectors
• CPC Class Codes: H01L 24/73 Means for bonding being of different types provided for in two or more of groups H01L24/10, H01L24/18, H01L24/26, H01L24/34, H01L24/42, H01L24/50, H01L24/63, H01L24/71
• 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 33/486 adapted for surface mounting
• CPC Class Codes: H01L 33/641 characterized by the materials
• CPC Class Codes: H01L 33/647 the elements conducting electric current to or from the semiconductor body

Abstract

A light-emitting diode (LED) structure with an improved heat transfer path with a lower thermal resistance than conventional LED lamps is provided. For some embodiments, a surface-mountable light-emitting diode structure is provided having an active layer deposited on a metal substrate directly bonded to a metal plate that is substantially exposed for low thermal resistance by positioning it on the bottom of the light-emitting diode structure. This metal plate can then be soldered to a printed circuit board (PCB) that includes a heat sink. For some embodiments of the invention, the metal plate is thermally and electrically conductively connected through several heat conduction layers to a large heat sink that may be included in the structure.

Claims

1. A light-emitting diode structure comprising:

a light-emitting diode semiconductor layer disposed directly adjacent a metal substrate enclosed in a ceramic casing;

a secondary metal plate electrically connected to a bond pad on the semiconductor layer and exposed through a bottom portion of the ceramic casing;

a primary metal plate having an upper and a lower tier, wherein the upper tier of the primary metal plate is electrically and thermally conductively connected to the metal substrate via a first metal bonding layer and enclosed in the ceramic casing and the lower tier of the primary metal plate is exposed through a bottom portion of the casing; and

a second metal bonding layer disposed below the ceramic casing and the lower tier of the primary metal plate.

2. The light-emitting diode structure of claim 1, further comprising:

a first conductivity layer for external connection, wherein the second metal bonding layer is situated between the lower tier of the primary metal plate and the first conductivity layer; and

a third metal bonding layer situated between a lower tier of the secondary metal plate and a second conductivity layer for external connection.

3. The light-emitting diode structure of claim 2, further comprising:

a dielectric layer for heat conduction sandwiched between said conductivity layers and a heat sink, wherein the heat sink is exposed at the bottom of the light-emitting diode structure.

4. The light-emitting diode structure of claim 2 wherein the three metal bonding layers comprise at least one of Au—

Sn, Ag—

Sn, or a Sn alloy.

5. The light-emitting diode structure of claim 1 wherein the casing comprises at least one of aluminum nitride (AlN) or alumina (Al₂O₃).

6. The light-emitting diode structure of claim 2 wherein at least one of the conductivity layers comprises a printed circuit board (PCB).

7. The light-emitting diode structure of claim 3 wherein the dielectric layer comprises anodized aluminum.

8. The light-emitting diode structure of claim 1 wherein metal vias connect the upper and lower tiers of the primary metal plate.

9. The light-emitting diode structure of claim 1, wherein the metal substrate comprises at least one of copper, a copper alloy, or a composite metal alloy.

10. The light-emitting diode structure of claim 1, wherein the primary metal plate is larger than the secondary metal plate.

11. A light-emitting diode (LED) structure comprising:

an LED semiconductor layer disposed directly on a metal substrate, wherein the semiconductor layer and the metal substrate are enclosed in a ceramic casing;

a primary metal plate having an upper and a lower tier, wherein the upper tier of the primary metal plate is electrically and thermally coupled to the metal substrate and enclosed in the ceramic casing and the lower tier of the primary metal plate is external to the casing;

a secondary metal plate having an upper and a lower tier, wherein the upper tier of the secondary metal plate is electrically coupled to the semiconductor layer and enclosed in the ceramic casing and the lower tier of the secondary metal plate is external to the casing; and

a first metal bonding layer disposed below the ceramic casing and the lower tier of the primary metal plate.

12. The LED structure of claim 11, wherein the semiconductor layer comprises AlInGaN or AlInGaP.

13. The LED structure of claim 11, wherein the metal substrate comprises at least one of copper, a copper alloy, or a composite metal alloy.

14. The LED structure of claim 11, wherein the casing comprises at least one of aluminum nitride (AlN) or alumina (Al₂O₃).

15. The LED structure of claim 11, wherein the thickness of the upper tier of the primary or the secondary metal plate is about 1 to 20 μ

m.

16. The LED structure of claim 11, wherein one or more metal vias connect the upper and lower tiers of the primary or the secondary metal plate through the casing.

17. The LED structure of claim 11, further comprising first and second conductivity layers for external connection coupled to the lower tiers of the primary and secondary metal plates, respectively.

18. The LED structure of claim 17, wherein at least one of the first and second conductivity layers comprises a printed circuit board (PCB).

19. The LED structure of claim 17, further comprising a dielectric layer disposed adjacent to the first and second conductivity layers.

20. The LED structure of claim 19, wherein the dielectric layer comprises anodized aluminum.

21. The LED structure of claim 19, further comprising a heat sink disposed adjacent to the dielectric layer.

22. The LED structure of claim 17, further comprising a second metal bonding layer between the metal substrate and the upper tier of the primary metal plate, wherein the first metal bonding layer is disposed between the lower tier of the primary metal plate and the first conductivity layer, and wherein a third metal bonding layer is disposed between the lower tier of the secondary metal plate and the second conductivity layer.

23. The LED structure of claim 22, wherein the first, second, or third metal bonding layer comprises at least one of Au—

Sn, Ag—

Sn, or a Sn alloy.