Side-view surface mount white LED

• US 7,649,209 B2
• Filed: 04/24/2007
• Issued: 01/19/2010
• Est. Priority Date: 04/24/2006
• Status: Active Grant

• Current Assignee: Creeled Incorporated
• Original Assignee: CREE Incorporated (Wolfspeed, Inc.)
• Inventors: Bergmann, Michael J., Collins, Brian T., Emerson, David T., Hussell, Christopher P.
• Primary Examiner(s): Smith; Zandra
• Assistant Examiner(s): Patton; Paul E
• Application Number:
  US11/739,307
• Publication Number:
  US 20070262339A1
• Time in Patent Office: 1,001 Days
• Field of Search: 257/100, 257/81, 257/98, 257/99, 362/612, 345/82, 438/22, 438/26, 438/27, 438/29
• US Class Current: 257/98
• CPC Class Codes: C09K 11/7731 with alkaline earth metals
• CPC Class Codes: G02B 6/0023 provided by one optical element, or plurality thereof, placed between the light guide and the light source, or around the light source
• CPC Class Codes: G02B 6/0068 Arrangements of plural sources, e.g. multi-colour light sources
• CPC Class Codes: G02B 6/0073 Light emitting diode [LED]
• 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 2224/48465 the other connecting portion not on the bonding area being a wedge bond, i.e. ball-to-wedge, regular stitch
• 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 2924/00012 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 2924/01322 Eutectic Alloys, i.e. obtained by a liquid transforming into two solid phases
• CPC Class Codes: H01L 2924/181 Encapsulation
• CPC Class Codes: H01L 2933/0091 Scattering means in or on the semiconductor body or semiconductor body package H01L33/22 takes precedence
• CPC Class Codes: H01L 33/486 adapted for surface mounting
• CPC Class Codes: H01L 33/502 Wavelength conversion materials
• CPC Class Codes: H01L 33/52 Encapsulations
• CPC Class Codes: Y02B 20/00 Energy efficient lighting technologies, e.g. halogen lamps or gas discharge lamps

Abstract

A light emitting diode is disclosed. The diode includes a package support and a semiconductor chip on the package support, with the chip including an active region that emits light in the visible portion of the spectrum. Metal contacts are in electrical communication with the chip on the package. A substantially transparent encapsulant covers the chip in the package. A phosphor in the encapsulant emits a frequency in the visible spectrum different from the frequency emitted by the chip and in response to the wavelength emitted by the chip. A display element is also disclosed that combines the light emitting diode and a planar display element. The combination includes a substantially planar display element with the light emitting diode positioned on the perimeter of the display element and with the package support directing the output of the diode substantially parallel to the plane of the display element.

Claims

1. A light emitting diode comprising:

a package support;

a semiconductor chip on said package support, said chip including an active region that emits radiation in the visible or UV portion of the spectrum;

metal contacts in electrical communication with said chip on said package;

a substantially transparent encapsulant covering said chip in said package;

a phosphor in said encapsulant that emits radiation in the visible spectrum different from the radiation emitted by said chip and in response to the wavelength emitted by said chip; and

a diffuser distributed in a pre-form and with said pre-form positioned within said encapsulant adjacent said diode.

2. A light emitting diode according to claim 1 comprising a diode and a phosphor with combined output radiation that produce white light.

3. A light emitting diode according to claim 2 wherein said diode emits in the blue portion of the visible spectrum.

4. A light emitting diode according to claim 2 wherein said phosphor is selected from the group consisting of:

YAG;

Ce, (Sr,Ba)₂SiO₄;

Eu, CaGa₂S₄;

Eu, SrGa₂S₄;

Eu, and (Sr,Ca)S;

Eu, and combinations thereof.

5. A light emitting diode according to claim 1 wherein said phosphor is dispersed within said encapsulant.

6. A light emitting diode according to claim 1 wherein said phosphor is packaged in a pre-form and positioned within said encapsulant.

7. A light emitting diode according to claim 1 further comprising a diffuser dispersed within said encapsulant.

8. A light emitting diode according to claim 1 wherein said encapsulant defines a meniscus with respect to said package and said chip.

9. A display element comprising the combination of a light emitting diode and a planar display element, the combination comprising:

a substantially planar display element;

a light emitting diode positioned on the perimeter of said display element and including;

a reflective package support that directs the output of said diode substantially parallel to the plane of said display element;

a semiconductor chip on said reflective package support, said chip including an active region that emits radiation in the visible or UV portion of the spectrum;

metal contacts in electrical communication with said chip on said reflective package;

a substantially transparent encapsulant covering said chip in said reflective package, said encapsulant forming a negative meniscus; and

;

a phosphor in said encapsulant that emits radiation in the visible spectrum different from the radiation emitted by said chip and in response to the wavelength emitted by said chip.

10. display element according to claim 9 comprising a diode and a phosphor with combined output frequencies that produce white light.

11. A display element according to claim 9 comprising a liquid crystal display.

12. A display element according to claim 9 comprising a color filter.

13. A display element according to claim 9 comprising a polarizer.

14. A display element according to claim 9 comprising a plurality of phosphors in said encapsulant that emit radiation at different wavelengths from one another.

15. A light emitting diode comprising:

a package support;

a semiconductor chip on said package support, said chip including an active region that emits radiation in the visible or UV portion of the spectrum;

metal contacts in electrical communication with said chip on said package;

a substantially transparent encapsulant covering said chip in said package; and

a phosphor in said encapsulant that emits radiation in the visible spectrum different from the radiation emitted by said chip and in response to the wavelength emitted by said chip, with more than 50 percent of the phosphor positioned in the lower 25 percent of the encapsulant.

16. A light emitting diode according to claim 15 wherein said diode emits in the blue portion of the visible spectrum and the combined output radiation of said diode and said phosphor produces white light.

17. The combination of:

a planar display element; and

a light emitting diode according to claim 15 positioned as a side view surface mount diode on the perimeter of said display element to transmit its radiation beam parallel to the plane of said display element.

18. A light emitting diode comprising:

a package support;

a semiconductor chip on said package support, said chip including an active region that emits radiation in the visible or UV portion of the spectrum;

metal contacts in electrical communication with said chip on said package;

a substantially transparent encapsulant covering said chip in said package;

a phosphor in said encapsulant that emits radiation in the visible spectrum different from the radiation emitted by said chip and in response to the wavelength emitted by said chip; and

a physical spacer element between said chip and said phosphor.

19. A light emitting diode according to claim 18 wherein said diode emits in the blue portion of the visible spectrum and the combined output radiation of said diode and said phosphor produces white light.

20. The combination of:

a planar display element; and

a light emitting diode according to claim 18 positioned as a side view surface mount diode on the perimeter of said display element to transmit its radiation beam parallel to the plane of said display element.