LIGHT-EMITTING DIODE LAMP WITH LOW THERMAL RESISTANCE

• US 20070241363A1
• Filed: 04/12/2006
• Published: 10/18/2007
• 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
• Granted Patent: US 7,863,639 B2
• Time in Patent Office: Days
• US Class Current: 257/103
• 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 active layer deposited on a metal substrate enclosed in a casing;

a secondary metal plate electrically connected to a bond pad on the active layer; and

a primary metal plate electrically and thermally conductively connected to the metal substrate via a metal bonding layer, wherein the primary and secondary metal plates are exposed through a bottom portion of the casing and provide external electrical connections to the light-emitting diode structure.

2. 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.

3. The light-emitting diode structure of claim 1 wherein the metal bonding layer comprises at least one of Au—

Sn, Ag—

Sn, or a Sn alloy.

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

5. The light-emitting diode structure of claim 1 wherein the primary metal plate and secondary metal plate extend laterally beyond the casing.

6. The light-emitting diode structure of claim 1 wherein the casing is cylindrical.

7. A light-emitting diode structure comprising:

a light-emitting diode semiconductor active layer deposited on a metal substrate enclosed in a casing;

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

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 casing and the lower tier of the primary metal plate is exposed through a bottom portion of the casing.

8. The light-emitting diode structure of claim 7, further comprising:

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

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

9. The light-emitting diode structure of claim 8, 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.

10. The light-emitting diode structure of claim 8 wherein the three metal bonding layers comprise at least one of Au—

Sn, Ag—

Sn, or a Sn alloy.

11. The light-emitting diode structure of claim 7 wherein the casing comprises at least one of aluminum nitride (AlN) or alumina (Al₂O₃).

12. The light-emitting diode structure of claim 8 wherein at least one of the conductivity layers comprises a printed circuit board (PCB).

13. The light-emitting diode structure of claim 9 wherein the dielectric layer comprises anodized aluminum.

14. The light-emitting diode structure of claim 7 wherein metal vias connect the upper and lower tiers of the primary metal plate.

15. A light-emitting diode structure comprising:

a light-emitting diode semiconductor active layer deposited on a metal substrate enclosed in a casing;

a secondary metal plate electrically connected to a bond pad on the active layer; and

a primary metal plate electrically and thermally conductively connected to the metal substrate via a first metal bonding layer, wherein the primary and secondary metal plates are positioned at an interior bottom surface of the casing and extend laterally through the casing to provide external electrical connections for the light-emitting diode structure.

16. The light-emitting diode structure of claim 15, further comprising:

an upper thermal conductivity layer situated below a bottom surface of the casing;

a second metal bonding layer situated between the upper thermal conductivity layer and a lower thermal conductivity layer; and

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

17. The light-emitting diode structure of claim 15 wherein the casing comprises at least one of aluminum nitride (AlN) or alumina (Al₂O₃).

18. The light-emitting diode structure of claim 16 wherein the first and second metal bonding layers comprise at least one of Au—

Sn, Ag—

Sn or a Sn alloy.

19. The light-emitting diode structure of claim 16 wherein the upper and lower conductivity layers comprise at least one of silver (Ag) paste or gold (Au) paste.

20. The light-emitting diode structure of claim 16 wherein the dielectric layer comprises anodized aluminum.

21. A light-emitting diode structure comprising:

a light-emitting diode semiconductor active layer deposited on a metal substrate enclosed in a casing, wherein a p-doped side of the active layer is intimately coupled to the metal substrate;

a secondary metal plate electrically connected to a bond pad on the active layer; and

a primary metal plate electrically and thermally conductively connected to the metal substrate via a metal bonding layer, wherein the primary and secondary metal plates are exposed through a bottom portion of the casing and provide external electrical connections to the light-emitting diode structure.

22. The light-emitting diode structure of claim 21 wherein the metal substrate comprises at least one of copper, a copper alloy, or a composite metal alloy.

23. The light-emitting diode structure of claim 21 wherein the metal bonding layer comprises at least one of Au—

Sn, Ag—

Sn, or a Sn alloy.

24. The light-emitting diode structure of claim 21 wherein the primary metal plate is larger than the secondary metal plate.

25. The light-emitting diode structure of claim 21 wherein the primary metal plate and secondary metal plate extend laterally beyond the casing.