Light-emitting diode lamp with low thermal resistance

• US 8,373,195 B2
• Filed: 12/13/2011
• Issued: 02/12/2013
• 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:
  US13/324,859
• Publication Number:
  US 20120132952A1
• Time in Patent Office: 427 Days
• Field of Search: 257/625, 257/703, 257/705, 257/E33.051, 257/E23.051, 257/E21.075, 362/218, 362/264, 362/547
• 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 2224/32245 the item being metallic
• CPC Class Codes: H01L 2224/48227 connecting the wire to a bond pad of the item
• 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 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 substrate directly bonded to a metal plate that is substantially exposed for low thermal resistance by positioning the metal plate at the bottom of the light-emitting diode structure. This metal plate may 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 coupled 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 substrate enclosed in a casing;

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

a primary metal plate electrically and thermally conductively coupled to the 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;

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

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

a dielectric layer for heat conduction interposed 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.

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

3. The light-emitting diode structure of claim 1, wherein the first and second metal bonding layers comprise at least one of Au—

Sn, Ag—

Sn or a Sn alloy.

4. The light-emitting diode structure of claim 1, wherein the upper and lower conductivity layers comprise at least one of silver (Ag) paste or gold (Au) paste.

5. The light-emitting diode structure of claim 1, wherein the dielectric layer comprises anodized aluminum.

6. The light-emitting diode structure of claim 1, wherein the substrate comprises copper.

7. A light-emitting diode structure comprising:

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

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

a primary metal plate electrically and thermally conductively coupled to the 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 beyond an upper portion of the casing to provide external electrical connections for the light-emitting diode structure; and

an upper thermal conductivity layer disposed below a bottom surface of the casing.

8. The light-emitting diode structure of claim 7, wherein the substrate comprises copper.

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

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

10. The light-emitting diode structure of claim 9, further comprising:

a dielectric layer for heat conduction interposed 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.