Light source

• US 20020163006A1
• Filed: 04/23/2002
• Published: 11/07/2002
• Est. Priority Date: 04/25/2001
• Status: Active Grant

• Current Assignee: Document Security Systems, Inc.
• Original Assignee: Avago Technologies ECBU IP Singapore Pte Limited (Broadcom, Inc.)
• Inventors: Lim, Seong Choon, Yoganandan, Sundar A/L Natarajan
• Granted Patent: US 6,949,771 B2
• Time in Patent Office: Days
• US Class Current: 257/81
• CPC Class Codes: H01L 2224/45144 Gold (Au) as principal constituent
• 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 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 2924/10253 Silicon [Si]
• CPC Class Codes: H01L 2924/3025 Electromagnetic shielding
• CPC Class Codes: H01L 33/486 adapted for surface mounting
• CPC Class Codes: H01L 33/54 having a particular shape
• CPC Class Codes: H01L 33/642 characterized by the shape
• CPC Class Codes: H05K 1/183 Components mounted in and supported by recessed areas of the printed circuit board
• CPC Class Codes: H05K 2201/0394 Conductor crossing over a hole in the substrate or a gap between two separate substrate parts
• CPC Class Codes: H05K 2201/10106 Light emitting diode [LED]
• CPC Class Codes: H05K 3/0052 Depaneling, i.e. dividing a panel into circuit boards; Working of the edges of circuit boards
• CPC Class Codes: H05K 3/403 Edge contacts; Windows or holes in the substrate having plural connections on the walls thereof H05K3/4092 takes precedence
• CPC Class Codes: H05K 3/42 Plated through-holes or plated via connections

Abstract

A light source suitable for surface mounting onto a printed circuit board. The light source includes a planar substrate with a centrally positioned aperture. A light emitting diode is mounted on a metallic layer covering the bottom of the aperture, and is encapsulated by a transparent encapsulant material. The metallic layer provides a thermal path for heat generated by the light emitting diode.

Claims

1. A light source comprising:

a substrate having opposing first and second surfaces, the substrate defining an aperture extending between the first and second surfaces,

a platform covering an opening of the aperture adjacent the first surface,

a light emitting diode mounted on the platform within the aperture, and

a transparent encapsulant material encapsulating the light emitting diode in the aperture.

3. A light source as claimed in claim 1, wherein the aperture comprises a side wall tapering outwards towards the second surface.

4. A light source as claimed in claim 3, wherein the platform extends over the side wall.

5. A light source as claimed in claim 1, wherein the platform presents a reflective surface to the light emitting diode.

6. A light source as claimed in claim 1, wherein the platform comprises a first surface facing the aperture on which the light emitting diode is mounted, and an opposite second surface exposed on the outside of the light source.

7. A light source as claimed in claim 1, wherein the platform is made from thermally conductive material for conducting heat away from the light emitting diode.

8. A light source as claimed in claim 1, wherein the platform is made of metal.

9. A light source as claimed in claim 8, wherein the metal platform is plated onto the substrate.

10. A light source as claimed in claim 9, wherein the metal platform comprises layers of different metals.

11. A light source as claimed in claim 1, wherein the substrate is made from an electrically and thermally insulating material.

12. A light source as claimed in claim 1, wherein the transparent encapsulant material is bonded to the second surface of the substrate.

13. A light source as claimed in claim 12, wherein the transparent encapsulant material is molded to form a focussing dome over the light emitting diode.

14. A light source as claimed in claim 1, further comprising

a first electrically-conductive interconnect extending between the first and second surfaces, the first interconnect having a terminal on the second surface coupled to the light emitting diode and an exposed pad on the first surface for coupling to external circuitry, and

a second electrically-conductive interconnect extending between the first and second surfaces, the second interconnect having a terminal on the upper surface coupled to the light emitting diode and a exposed pad on the first surface for coupling to external circuitry.

15. A light source as claimed in claim 14, wherein the substrate defines first and second vias extending between the upper and lower surfaces, a portion of each of the first and second interconnects extending through the first and second vias respectively.

2. A light source as claimed in claim 2, wherein the platform extends beyond the opening of the aperture over the first surface.

16. A method of manufacturing a light source comprising:

providing a substrate with opposing first and second surfaces,

plating a first surface of the substrate with a metallic layer,

drilling a hole through the substrate from the second surface up to the metallic layer on the first surface such that the metallic layer provides a platform covering the opening of the aperture adjacent the first surface,

mounting a light emitting diode on the platform within the aperture, and

encapsulating the light emitting diode in the aperture with a transparent encapsulant material.