LED device with combined Reflector and Spherical Lens

• US 20080246044A1
• Filed: 04/09/2007
• Published: 10/09/2008
• Est. Priority Date: 04/09/2007
• Status: Abandoned Application

• Current Assignee: Avago Technologies ECBU IP Singapore Pte Limited (Broadcom, Inc.)
• Original Assignee: Avago Technologies ECBU IP Singapore Pte Limited (Broadcom, Inc.)
• Inventors: Pang, Siew It
• Application Number:
  US11/733,105
• Publication Number:
  US 20080246044A1
• Time in Patent Office: Days
• US Class Current: 257/98
• CPC Class Codes: H01L 2224/48091 Arched
• 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 2924/181 Encapsulation
• CPC Class Codes: H01L 2924/1815 Shape
• CPC Class Codes: H01L 33/508 having a non-uniform spatial arrangement or non-uniform concentration, e.g. patterned wavelength conversion layer, wavelength conversion layer with a concentration gradient of the wavelength conversion material
• CPC Class Codes: H01L 33/54 having a particular shape

Abstract

A light source and method for making the same are disclosed. The light source includes a substrate having a top surface, a die, and a first encapsulating layer. The die includes an LED attached to the top surface and electrically connected to traces in the substrate that power the LED. The first dome covers the die and is in contact with the top surface, the dome having an angle of contact greater than 90° with respect to the top surface. The first dome has an outer surface that includes a truncated sphere characterized by a center for the spherical portion of the surface, and the die is situated at a position below the center. A second dome can be provided around the outside of the first dome. In addition, the first dome may include light converting and/or scattering materials.

Claims

1. A light source comprising:

a substrate having a first top surface;

a die comprising a second top surface and an LED, said die being attached to said first top surface; and

a first dome covering said second top surface of said die, said first dome making direct contact with said second top surface and having an angle of contact greater than 90% with respect to said second top surface.

4. The light source of claim 1 wherein said die further comprises a bottom surface and a plurality of side walls connecting said first top surface to said bottom surface and wherein said first dome covers at least a portion of said side walls of said die.

5. The light source of claim 1 wherein said first dome comprises a transparent epoxy or silicone.

6. The light source of claim 1 wherein said first top surface of said substrate on which said die is mounted is surrounded by a recessed area having side surfaces extending from said first top surface and wherein said first dome covers a portion of said side surfaces.

7. The light source of claim 1 further comprising a second dome surrounding said first dome, and wherein said first dome comprises a light converting material that converts light emitted by said LED to light having a different spectrum.

8. The light source of claim 7 wherein said light converting material comprises particles of a phosphor.

2-3. -3. (canceled)

9-10. -10. (canceled)

11. A method for fabricating a light source, said method comprising:

attaching a die having an LED thereon to a substrate, said die having a top surface, a bottom surface, and a plurality of side surfaces, said die being attached to said substrate by said bottom surface;

connecting contacts on said LED to traces in said substrate;

dispensing a first droplet of a first precursor of an encapsulating material on said top surface of said die; and

curing said first droplet to form a first dome having an outer surface over said die, said outer surface comprising a truncated sphere.

12. The method of claim 11 wherein said first droplet is allowed to cover a portion of said side surfaces prior to being cured.

13. The method of claim 11 wherein said first precursor comprises a light converting material that converts light emitted by said LED to light having a different spectrum.

14. The method of claim 11 further comprising dispensing a second droplet of a second precursor of an encapsulating material on said first droplet after said first droplet has cured to form a second dome that covers said first dome.

15. The method of claim 14 wherein said second droplet comprises an outer surface comprising a truncated sphere.

16. The method of claim 11 wherein said substrate comprises a top surface and a plurality of side surfaces, said die being attached to said top surface, and wherein said first droplet is allowed to cover a portion of said side surfaces of said substrate prior to being cured.

17. The method of claim 16 wherein said first precursor comprises a light converting material suspended in a transparent carrier and said second precursor comprises said transparent carrier without said light converting material.

18. The method of claim 17 wherein said transparent carrier comprises a transparent epoxy or silicone.

19. The method of claim 17 wherein said light converting material comprises particles of a phosphor

20. The method of claim 11 wherein said first dome comprises a diffusant.