Semiconductor light emitting device

• US 6,940,704 B2
• Filed: 01/24/2001
• Issued: 09/06/2005
• Est. Priority Date: 01/24/2001
• Status: Expired due to Fees

• Current Assignee: Gelcore (General Electric Company)
• Original Assignee: Gelcore (General Electric Company)
• Inventors: Stalions, Drake Charles
• Primary Examiner(s): O'Shea, Sandra
• Assistant Examiner(s): Lee, Guiyoung
• Application Number:
  US09/767,695
• Publication Number:
  US 20020097579A1
• Time in Patent Office: 1,686 Days
• Field of Search: 362/241, 362/247, 362/249, 362/800, 362/311, 257/81, 257/82, 257/94, 257/95, 257/99, 257/103
• US Class Current: 361/241
• 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 2924/0002 Not covered by any one of groups H01L24/00, H01L24/00 and H01L2224/00
• CPC Class Codes: H01L 33/486 adapted for surface mounting
• CPC Class Codes: H01L 33/58 Optical field-shaping elements
• 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 33/64 Heat extraction or cooling elements

Abstract

A light emitting diode (LED) including a combination of features that enable the LED to produce a high-brightness predetermined radiation pattern. The combination of features enable the LED to function cooler and more reliably at a higher drive currents and elevated ambient temperatures, and therefore emit light of increased brightness, without overheating, and to have a particular radiation pattern. In particular, a surface mount that is capable of operating at high drive currents and high ambient temperatures is disclosed. The LED comprises a surface mount package having a metal lead frame having mass sufficient to provide low thermal resistance, at least one anode contact pad and at least one cathode contact pad. The LED also includes a reflector positioned within the package, a semiconductor die and an optional focusing dome. The semiconductor die comprises a transparent substrate and a semiconductor component and is positioned within the package so that the semiconductor component and the substrate are arranged side-by-side over the reflector (flop-chip). Alternatively, the die is positioned within the package so that the substrate is on top of the semiconductor component (flip-chip). The optional focusing dome is operative to refract light emitted from the semiconductor die and light reflected from the reflector to create a predetermined radiation pattern.

Claims

1. A light emitting diode comprising:

a first metal lead having mass sufficient to provide low thermal resistance including at least one anode contact pad and at least one anode contact for electrical connection to a circuit board;

a second metal lead having mass sufficient to provide low thermal resistance including at least one cathode contact pad and at least one cathode contact for electrical connection to said circuit board;

said cathode contact pad and said cathode contact comprised of a contiguous metal lead and said anode contact pad and said anode contact comprised of a contiguous metal lead;

a reflector;

a semiconductor die, comprising a transparent substrate and a light emitting component, wherein the semiconductor die connects to the metal lead frame via at least two solder bridges positioned between said anode contact pad and said cathode contact pad over the reflector; and

,

said electrical connection of said circuit board to said semiconductor die being free of wire bond attachment.

2. The light emitting diode of claim 1 further comprising a focusing dome operative to refract light emitted from the semiconductor die and light reflected from the reflector to create a predetermined radiation pattern.

3. The light emitting diode of claim 2 wherein the radiation pattern comprises a 120 degree illumination pattern.

4. The light emitting diode of claim 1 wherein the reflector comprises a truncated cone shape.

5. The light emitting diode of claim 1 wherein the lead frame comprises a lead frame having a thermal resistance less than 300 K°

/W.

6. The light emitting diode of claim 1 wherein the lead frame comprises copper.

7. The light emitting diode of claim 1 wherein the lead frame comprises silver-plated copper.

8. The light emitting diode of claim 1 wherein the light emitting component comprises a GaN based compound semiconductor and the substrate comprises sapphire.

9. The light emitting diode of claim 1 wherein the light emitting component comprises an AllnGaP compound semiconductor and the substrate comprises GaP.

10. The light emitting diode of claim 1 wherein the substrate is positioned on top of the light emitting component over the reflector.

11. The light emitting diode of claim 1 wherein the metal lead frame comprises three anode contact pads and one cathode contact pad.

12. A light emitting diode comprising:

a first metal lead having mass sufficient to provide low thermal resistance including at least one anode contact pad and at least one anode contact for electrical connection to a circuit board;

a second metal lead having mass sufficient to provide low thermal resistance including at least one cathode contact pad and at least one cathode contact for electrical connection to said circuit board;

said cathode contact pad and said cathode contact being comprised of a contiguous metal lead and said anode contact pad and said anode being comprised of a contiguous metal lead;

a semiconductor die comprising a transparent substrate and a light emitting region, wherein the transparent substrate connects to the metal lead frame via a solder bridge between one of said anode contact pad and said cathode contact pad, and said light emitting region connects to the metal lead frame via a solder bridge between the other of said anode contact pad and said cathode contact pad; and

,

said electrical connection of said circuit board to said semiconductor die being free of wire bond attachment.