LED mounting having increased heat dissipation

• US 20060202210A1
• Filed: 03/08/2005
• Published: 09/14/2006
• Est. Priority Date: 03/08/2005
• Status: Active Grant

• Current Assignee: Document Security Systems, Inc.
• Original Assignee: Avago Technologies ECBU IP Singapore Pte Limited (Broadcom, Inc.)
• Inventors: Mok, Thye Linn, Ng, Shin Wen, Tan, Siew Kim
• Granted Patent: US 7,262,438 B2
• Time in Patent Office: Days
• US Class Current: 257/79
• CPC Class Codes: H01L 2224/48091 Arched
• CPC Class Codes: H01L 2224/73265 Layer and wire connectors
• 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 33/54 having a particular shape
• CPC Class Codes: H01L 33/642 characterized by the shape
• CPC Class Codes: H01L 33/647 the elements conducting electric current to or from the semiconductor body

Abstract

There is disclosed a system and method for increasing heat dissipation of LED displays by using the current PCB packaging mounted to a LCD panel support structure thereby eliminating the need for a metal core PCB. In one embodiment, reverse mounted LEDs having heat dissipation pads are used to optimize heat transfer to a metal layer which is then placed in contact with the LCD support structure.

Claims

1. An LED assembly comprising:

a substrate having a heat-sink pad forming a bottom surface thereof,

an LED mounted at least partially on said substrate and having a portion of said LED physically bonded to the heat sink pad; and

wire bond pads on a top surface of said substrate, said wire bond pads electrically connected to said LED.

2. The assembly of claim 1 further comprising:

a reflector cup constructed within said substrate, said LED positioned within said reflector cup.

3. The assembly of claim 2 wherein said portion of said LED in contact with said heat-sink pad is a portion designed for the dissipation of heat from said LED.

4. The assembly of claim 2 further comprising:

an optical dome covering said LED and said reflector cup.

5. The assembly of claim 4 wherein said optical dome is part of a substrate positioned to cover said top surface.

6. The assembly of claim 3 further comprising:

a separate substrate positioned over said substrate, said separate substrate having electrical contacts for making electrical contact with at least a portion of said wire bond pads; and

wherein said separate substrate has constructed therein provision for allowing light from said LED to be visible to an observer.

7. The assembly of claim 6 further comprising:

a support structure connected to said heat-sink pad.

8. The assembly of claim 7 wherein said PCB substrate contains a plurality of said LEDs all in contact with said heat-sink and wherein said heat-sink is in contact with said support structure.

9. The assembly of claim 8 wherein said separate substrate has constructed therein provision allowing light from said plurality of LEDs to be visible to an observer.

10. An array of LEDs, said array comprising:

a first substrate having reflector cups constructed therein, said reflector cups for mounting said LEDs therein;

said first substrate having attached thereto a heat conducting layer in physical contact with a first surface of mounted ones of said LEDs;

said first substrate comprising;

electrical pads for connecting to mounted ones of said LEDs, said electrical pads positioned so as to communicate electrical control signals from a mating substrate, said mating substrate having constructed therein control circuitry for controlling said LEDs;

said LED array further comprising;

a heat conducting support structure in non-electrical contact with said heat conducting layer so as to transfer away heat generate from the operation of mounted ones of said LEDs.

11. The array of claim 10 wherein said mating substrate comprises:

a plurality of optical domes for allowing light from mounted ones of said LEDs to be radiated away from said mating substrate, said light radiating from a second surface of said LEDs.

12. The array of claim 10 wherein said heat conducting layer is a metal layer.

13. The array of claim 10 wherein said heat conducting support structure is a metal structure.

14. The array of claim 10 wherein said heat conducting support structure is mated to said heat conducting layer with a thermally conductive, non-electrically conductive dielectric.

15. A method of constructing an LED array, said method comprising:

constructing in a first substrate a reflector area for mounting an LED therein, said reflector area containing a heat transfer material in contact with a bottom surface of said first substrate; and

constructing on a top surface of said first substrate contact pads for connecting with electrical contacts of a mounted LED, said contact pads also having area for making electrical contact with electrical contacts on a second substrate in contact with said top surface of said first substrate;

positioning said LED within said reflector area with a bottom surface of said LED that is physically bonded to said heat transfer material.

16. (canceled)

17. The method of claim 16 further comprising:

positioning a light dome over said reflector area to disperse light from a mounted LED.

18. The method of claim 17 further comprising:

constructing a plurality of said reflector areas of said first substrate.

19. The method of claim 18 further comprising:

mounting a plurality of said first substrates, each with a plurality of reflector areas upon a support structure to form a matrix array of LEDs.

20. The method of claim 17 further comprising:

mounting a plurality of said first substrates on a support structure to form an array of LEDs, said array being controlled from said second substrate.