Method And Apparatus For A Light Source

• US 20130050982A1
• Filed: 10/30/2012
• Published: 02/28/2013
• 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
• Granted Patent: US 9,041,046 B2
• Time in Patent Office: Days
• US Class Current: 362/84
• 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 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;

an 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 wavelength converting material is suspended within the low density layer in particle form; and

wherein the wavelength-converting material is precipitated on one side of wavelength converting layer defining the high density 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 wavelength converting 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 1, wherein the high density layer of the wavelength converting layer covers entirely the second surface of the substrate.

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

9. The light-emitting device of claim 8, 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.

10. 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.

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

12. 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 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 die attach pad and the first surface of the substrate are thermally coupled with a surface of the mobile device to dissipate heat generated from the light source die to the surface of the mobile device, and wherein the surface of the mobile device is in direct contact with the first surface of the substrate.

13. The flash system of claim 12, wherein the wavelength converting layer comprises:

a low density layer having wavelength converting particles suspended within the layer; and

a high density layer connected to the low density layer having precipitated wavelength converting particles.

14. The flash system of claim 12, wherein the high density layer has a substantially uniform thickness.

15. The flash system of claim 12, 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;

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

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; and

a second optical coupling layer encapsulating the second light source die, wherein the second optical layer extends over the wavelength converting layer, the second surface of the substrate and the second light source;

wherein the light emitted from the first light source die has a limited spectrum, and the first light source die is coupled with the wavelength converting layer for converting the limited spectrum of light to a broader spectrum light.

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

a low density layer having wavelength converting particles suspended within the layer; and

a high density layer connected to the low density layer and having precipitated wavelength converting particles.

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.