LED mounting having increased heat dissipation

• US 7,262,438 B2
• Filed: 03/08/2005
• Issued: 08/28/2007
• 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, Tan, Siew Kim, Ng, Shin Wen
• Primary Examiner(s): Kebede, Brook
• Application Number:
  US11/075,094
• Publication Number:
  US 20060202210A1
• Time in Patent Office: 903 Days
• Field of Search: 438/25, 438/106, 438/107, 438/110, 438/112, 438/124, 438/126, 438/127, 438/FOR.157, 438/122, 257 79-103, 257/622, 257/623, 257/687, 257/701, 257666-677, 257/E33.066
• US Class Current: 257/98
• 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 heat-sink pad;

a PCB substrate having a first major surface mated to said heat-sink pad;

an LED mounted at least partially inside an opening located on said PCB substrate and having a portion of said LED physically bonded to the heat sink pad thereby forming a heat dissipation path between said LED and said heat-sink pad; and

a first contact strip located on a second major surface opposing said first major surface of said PCB substrate, said first contact strip electrically connected to said LED for providing an electrical path that is separate from said heat dissipation path, thereby optimizing heat dissipation in said LED assembly.

2. The assembly of claim 1 wherein said opening located on said PCB substrate is configured as a reflector cup for reflecting light generated by 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. A method of constructing an LED array, said method comprising:

providing a mounting plate on which is mounted a first heat sink pad;

mating to said first heat sink pad, a bottom surface of a first PCB substrate;

providing in said first PCB substrate a reflector area for mounting a first LED therein, said reflector area containing a heat transfer material in contact with the first heat sink pad;

providing on a top surface of said first PCB substrate a first contact pad for connecting with an electrical contact of said first LED; and

positioning said first LED within said reflector area with a bottom surface of said LED in contact with said heat transfer material thereby providing a first heat dissipation path that is separate from an electrical path provided by the first contact pad.

6. The method of claim 5 further comprising:

positioning a first light dome over said reflector area in said first PCB substrate to disperse light from said first LED.

11. The method of claim 5, further comprising:

mounting on said mounting plate, a second heat sink pad;

mating to said second heat sink pad, a bottom surface of a second PCB substrate;

providing in said second PCB substrate a reflector area for mounting a second LED therein, said reflector area containing a heat transfer material in contact with the second heat sink pad;

providing on a top surface of said second PCB substrate a second contact pad for connecting with an electrical contact of said second LED; and

positioning said second LED within said reflector area with a bottom surface of said LED in contact with said heat transfer material thereby providing a second heat dissipation path that is separate from an electrical path provided by the second contact pad.

12. The method of claim 11, further comprising:

positioning a second light dome over said reflector area in said second PCB substrate to disperse light from said second LED.

7. An array of LEDs, the array comprising:

a heat dissipation bar;

a first LED assembly mounted on said heat dissipation bar; and

a second LED assembly mounted on said heat dissipation bar, wherein each of said first and second LED assemblies comprises;

a heat-sink pad, said heat-sink pad mounted on to said heat dissipation bar;

a PCB substrate having a first major surface mated to said heat-sink pad;

an LED mounted at least partially inside an opening located on said PCB substrate and having a portion of said LED physically bonded to the heat sink pad thereby forming a heat dissipation path between said LED and said heat-sink pad; and

a first contact strip located on a second major surface opposing said first major surface of said PCB substrate, said first contact strip electrically connected to said LED for providing an electrical path that is separate from said heat dissipation path, thereby optimizing heat dissipation in said array of LEDs.

8. The of claim 7 further comprising:

a back mounting plate to which is attached said heat dissipation bar.

9. The array of claim 8, further comprising:

a cover disposed over said first and second LED assemblies thereby allowing LED light to be visible externally.

10. The array of claim 9, further comprising:

a light diffuser for diffusing LED light generated by at least one of said first and second LED assemblies.