Method and apparatus for a light source

• US 9,041,046 B2
• Filed: 10/30/2012
• Issued: 05/26/2015
• Est. Priority Date: 03/15/2011
• Status: Active Grant

• Current Assignee: Avago Technologies International Sales Pte Limited (Broadcom, Inc.)
• Original Assignee: Avago Technologies General IP PTE Limited (Broadcom, Inc.)
• Inventors: Phang, Chin Ewe, Lim, Seong Choon, Ong, Eng Chuan
• Primary Examiner(s): Such, Matthew W
• Assistant Examiner(s): Kilpatrick, Warren H
• Application Number:
  US13/664,278
• Publication Number:
  US 20130050982A1
• Time in Patent Office: 938 Days
• Field of Search: 257/98, 257/E33.061, 362/84
• US Class Current: 257/99
• CPC Class Codes: G03B 2215/0567 Solid-state light source, e.g. LED, laser
• CPC Class Codes: H01L 2224/48091 Arched
• CPC Class Codes: H01L 2224/48227 connecting the wire to a bond pad of the item
• CPC Class Codes: H01L 2224/8592 Applying permanent coating, e.g. protective coating
• CPC Class Codes: H01L 25/0753 the devices being arranged next to each other
• 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 2933/0041 relating to wavelength conversion elements
• CPC Class Codes: H01L 2933/005 relating to encapsulations
• CPC Class Codes: H01L 33/486 adapted for surface mounting
• CPC Class Codes: H01L 33/507 the elements being in intimate contact with parts other than the semiconductor body or integrated with parts other than the semiconductor body
• 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 33/52 Encapsulations
• CPC Class Codes: H01L 33/60 Reflective elements

Abstract

A light-emitting device having a light source die mounted within an aperture is disclosed. The aperture is covered by a die attach pad on one side. The light source die is mounted on a die attach pad within the aperture. In one embodiment, an optical coupling layer can be formed within an aperture encapsulating a light source die. A wavelength converting layer can be formed on the substrate above the optical coupling layer. The wavelength converting layer can comprise a high density layer and a low density layer. The high density layer can comprise wavelength-converting material precipitated on one side of the wavelength converting layer. The low density layer can comprise the wavelength-converting material in particle form suspended within the wavelength converting layer. In one embodiment, the wavelength converting layer may be confined within the aperture of the substrate.

Claims

1. A light-emitting device, comprising:

a substrate having opposing first and second surfaces;

an aperture extending through the substrate from the first surface to the second surface of the substrate;

a die attach pad configured to cover the aperture at the first surface;

a light source die attached to the die attach pad;

an optical coupling layer substantially encapsulating the light source die within the aperture;

a wavelength converting layer formed on the optical coupling layer, wherein the wavelength converting layer comprises a low density layer and a high density layer; and

a wavelength-converting material formed within the wavelength converting layer;

wherein the high density layer has substantially higher density of the wavelength-converting material relative to the low density layer such that the wavelength converting material in the low density layer is suspended within the low density layer in particle form

but the wavelength-converting material in the high density layer is precipitated on one side of wavelength converting layer.

2. The light-emitting device of claim 1 further comprising an additional optical coupling layer, wherein the wavelength converting layer is sandwiched between the optical coupling layer and the additional optical coupling layer.

3. The light-emitting device of claim 2, wherein the additional optical coupling layer is substantially planarly parallel to the second surface of the substrate.

4. The light-emitting device of claim 3, wherein the additional optical coupling layer covers entirely the second surface of the substrate.

5. The light-emitting device of claim 2, wherein the wavelength converting layer is formed within the aperture.

6. The light-emitting device of claim 5, wherein:

the high density layer has a thickness and the low density layer has a thickness; and

the thickness of the high density layer is at least more than the thickness of the low density layer.

7. The light-emitting device of claim 2, wherein the wavelength converting layer, the optical coupling layer and the additional optical coupling layer are formed using substantially the same type of encapsulant.

8. The light-emitting device of claim 1, wherein the high density layer of the wavelength converting layer covers entirely the second surface of the substrate.

9. The light-emitting device of claim 1, wherein the wavelength converting layer is formed adjacent to the second surface of the substrate and outside the aperture.

10. The light-emitting device of claim 9, wherein:

the high density layer has a thickness and the low density layer has a thickness; and

the thickness of the high density layer is less than approximately half of the thickness of the low density layer.

11. The light-emitting device of claim 1, wherein the light-emitting device forms a portion of a camera device.

12. The light-emitting device of claim 1, wherein the density of the wavelength-converting material in the high density layer is substantially higher than the low density layer such that the wavelength-converting material in the low density layer is distinguishably visible under a microscope but the wavelength-converting material in the high density layer is visually visible.

13. A flash system for use in a mobile device, comprising:

a substrate having opposing first and second surfaces;

a plurality of conductors being form on at least one of the first and second surfaces;

an aperture extending through the substrate, from the first surface to the second surface of the substrate;

a die attach pad extending over and covering the first surface of the substrate;

a light source die attached on the die attach pad and disposed substantially within the aperture;

an optical coupling layer encapsulating the light source die; and

a wavelength converting layer comprising a low density layer and a high density layer disposed on the optical coupling layer such that the optical coupling layer is sandwiched between the wavelength converting layer and the die attach pad, wherein the high density layer has substantially higher density relative to the low density layer such that the low density layer is distinguishably visible under a microscope whereas the high density layer is visually visible precipitated particles on one side of the wavelength-converting material.

14. The flash system of claim 13, wherein the high density layer has a substantially uniform thickness.

15. The flash system of claim 13, wherein the wavelength converting layer is disposed within the aperture.

16. The flash system of claim 15, wherein the flash system further comprises an additional optical coupling layer disposed on the second surface of the substrate covering an opening of the aperture at the second surface of the substrate.

17. A lighting apparatus, comprising:

a substrate having a opposing first and second surfaces;

first and second apertures extending through the substrate from the first surface to the second surface of the substrate;

first and second die attach pads adjacent to the first surface of the substrate and substantially covering the first and second apertures;

a first light source die attached on the first die attach pad and disposed substantially within the first aperture for emitting light;

a second light source die attached on the second die attach pad and disposed substantially within the second aperture for emitting light;

a first optical coupling layer encapsulating the first light source die within the first aperture;

a wavelength converting layer formed on the first optical coupling layer but being confined within the first aperture, the wavelength converting layer being configured to cover the first light source die so as to convert the light emitted from the first light source die into a broader spectrum light; and

a second optical coupling layer encapsulating the second light source die, the wavelength converting layer that covers the first light source die and at least a portion of the second surface of the substrate such that the second optical coupling layer is configured to mix light emitted from the second light source die with the broader spectrum light from the wavelength converting layer.

18. The lighting apparatus of claim 17, wherein the wavelength converting layer comprises:

a low density layer of wavelength converting particles; and

a high density layer of the wavelength converting particles connected to the low density layer, wherein the high density layer has substantially higher concentration of the wavelength-converting particles relative to the low density layer such that the wavelength-converting particles in the high density layer is precipitated but the wavelength-converting particles in the low density layer is in particle form suspending within the low density layer.

19. The lighting apparatus of claim 18 further comprising a third light source die and a fourth light source die encapsulated by the second optical coupling layer, wherein light emitted by the third and fourth light source dies are mixed with the light emitted from the second light source die within the second optical coupling layer.

20. The lighting apparatus of claim 19, wherein:

the first light source die and the wavelength converting layer are configured to generate white light;

the second light source die is configured to generate light of a first color;

the third light source die is configured to generate red light of a second color; and

the fourth light source die is configured to generate light of a third color.