High powered light emitter packages with compact optics

• US 9,666,772 B2
• Filed: 04/29/2004
• Issued: 05/30/2017
• Est. Priority Date: 04/30/2003
• Status: Active Grant

• Current Assignee: Creeled Incorporated
• Original Assignee: CREE Incorporated (Wolfspeed, Inc.)
• Inventors: Keller, Bernd, Ibbetson, James, Bharathan, Jayesh
• Primary Examiner(s): Mondt, Johannes P
• Application Number:
  US10/836,743
• Publication Number:
  US 20040227149A1
• Time in Patent Office: 4,779 Days
• Field of Search: 257 99, 257100
• CPC Class Codes: H01L 2224/48091 Arched
• 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 2924/00014 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 2924/12044 OLED
• CPC Class Codes: H01L 33/54 having a particular shape
• CPC Class Codes: H01L 33/56 Materials, e.g. epoxy or silicone resin
• CPC Class Codes: H01L 33/58 Optical field-shaping elements
• CPC Class Codes: H01L 33/60 Reflective elements
• CPC Class Codes: H01L 33/641 characterized by the materials

Abstract

A light emitter includes a planar supporting surface, a light source positioned on the spreader region, and an encapsulant positioned on the spreader region to surround the light source. Except where constrained by adhesion to the planar supporting surface, the encapsulant is capable of expanding and contracting in response to a change in temperature so that forces caused by differences in the coefficient of thermal expansion between the different components is minimized. One or more reflective elements can be positioned proximate to the light source to increase the light emitting efficiency of the light emitter. The reflective elements can include a reflective layer on the spreader region and/or a reflective layer on a portion of the encapsulant.

Claims

1. A light emitter, comprising:

a substantially planar supporting surface comprising a thermally conductive heat spreader and a reflective layer on said thermally conductive heat spreader, said reflective layer shaped to define a discontinuity;

a solid state light source on said reflective layer and in thermal communication with said thermally conductive heat spreader to draw heat away from said light source, said supporting surface providing a substantially planar surface around said light source; and

an encapsulant on said substantially planar supporting surface and surrounding said light source, said reflective layer between said encapsulant and said thermally conductive heat spreader, said encapsulant only constrained at an interface with said solid state light source and said substantially planar supporting surface, such that said encapsulant is capable of expanding and contracting in response to a change in temperature;

wherein said encapsulant comprises a curved external surface and substantially straight surface which is inwardly angled with respect to said substantially planar supporting surface, said curved external surface adjacent to said substantially straight surface, said inwardly angled encapsulant surface both refracting and reflecting light emitted by said light source.

2. The emitter of claim 1, wherein a surface of said light source is adjacent to said supporting surface, said encapsulant covering all other surfaces of said light source.

3. The emitter of claim 1, wherein said encapsulant hermetically seals said light source, said hermetic seal remaining unbroken with the change in temperature.

4. The emitter of claim 1, wherein said reflective layer is reflective to the light emitted by said light source.

5. The emitter of claim 1, wherein said light source comprises a light emitting diode.

12. The emitter of claim 1, wherein said encapsulant is on a top surface of said substantially planar supporting surface.

13. The light emitter of claim 1, wherein an edge of said encapsulant is inwardly angled at a point of intersection with said substantially planar top surface of said reflective layer.

6. A light emitter, comprising:

a heat spreader comprising a substantially planar reflective top surface comprising a discontinuity;

a solid-state light source on said reflective top surface, with said heat spreader providing support for said light source and drawing heat away from said light source;

an encapsulant positioned to surround said light source, said encapsulant only constrained in the areas around said light source by adhesion to said heat spreader and the surfaces of said light source, such that said encapsulant is capable of expanding and contracting in response to a change in temperature;

wherein said encapsulant comprises a curved external surface and a substantially straight surface which is inwardly angled with respect to said substantially planar reflective top source, said curved external surface adjacent to said substantially straight surface, said inwardly angled encapsulant surface both refracting light emitted by said light source.

7. The emitter of claim 6, wherein said reflective top surface comprises a reflective layer comprising at least one of silver (Ag), aluminum (Al), or a combination thereof.

8. The emitter of claim 6, wherein said heat spreader comprises at least one of copper (Cu), aluminum (Al), aluminum nitride (AlN), aluminum oxide (AlO), silicon (Si), silicon carbide (SiC) and another thermally conductivity material which can dissipate heat away from said light source.

9. The emitter of claim 6, wherein the surface of said heat spreader comprises at least one of aluminum (Al), silver (Ag), and another material reflective at the wavelengths of interest.

10. The emitter of claim 6, wherein said encapsulant surrounds said light source and is directly on said light source.

11. The light emitter of claim 6, wherein said encapsulant is pre-molded lens and is directly on said light source.

14. The light emitter of claim 6, wherein edge of said encapsulant is inwardly angled at a point of intersection with said reflective top surface.

15. A light emitter, comprising:

a supporting surface comprising a heat spreader and a reflective layer, said reflective layer on said heat spreader;

a light source on said reflective layer; and

an encapsulant on said supporting surface and surrounding said light source, said encapsulant only constrained at an interface with said light source and said supporting surface;

wherein said encapsulant comprises a curved external surface and a substantially straight surface which is inwardly angled with respect to said supporting surface such that at least some light emitted by said light source is transmitted through said surface, said curved external surface adjacent to said substantially straight surface.