Thermal management system for L.E.D. arrays

• US 5,857,767 A
• Filed: 02/25/1997
• Issued: 01/12/1999
• Est. Priority Date: 09/23/1996
• Status: Expired due to Term

• Current Assignee: Relume Technologies, Inc. (Revolution Lighting Technologies, Inc.)
• Original Assignee: Relume Corporation
• Inventors: Hochstein, Peter A.
• Primary Examiner(s): Sember, Thomas M.
• Application Number:
  US08/805,763
• Time in Patent Office: 686 Days
• Field of Search: 362/294, 362/373, 362/800, 362/249, 362/235, 362/547
• US Class Current: 362/294
• CPC Class Codes: F21K 9/00 Light sources using semiconductor devices as light-generating elements, e.g. using light-emitting diodes [LED] or lasers
• CPC Class Codes: F21S 43/14 Light emitting diodes [LED]
• CPC Class Codes: F21S 45/48 with means for conducting heat from the inside to the outside of the lighting devices, e.g. with fins on the outer surface of the lighting device
• CPC Class Codes: F21V 29/70 characterised by passive heat-dissipating elements, e.g. heat-sinks
• CPC Class Codes: F21V 29/74 with fins or blades
• CPC Class Codes: F21V 29/763 the planes containing the fins or blades having the direction of the light emitting axis
• CPC Class Codes: F21V 29/85 characterised by the material liquid coolants F21V29/56
• CPC Class Codes: F21V 29/87 Organic material, e.g. filled polymer composites; Thermo-conductive additives or coatings therefor
• CPC Class Codes: F21V 29/89 Metals
• CPC Class Codes: F21V 31/005 Sealing arrangements therefor
• CPC Class Codes: F21Y 2115/10 Light-emitting diodes [LED]
• CPC Class Codes: G09F 9/33 being semiconductor devices, e.g. diodes
• 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 2924/0002 Not covered by any one of groups H01L24/00, H01L24/00 and H01L2224/00
• CPC Class Codes: H01L 33/642 characterized by the shape
• CPC Class Codes: H05K 1/0203 Cooling of mounted components H05K1/0272 takes precedence
• CPC Class Codes: H05K 1/056 the metal substrate being covered by an organic insulating layer
• CPC Class Codes: H05K 1/095 for polymer thick films, i.e. having a permanent organic polymeric binder
• CPC Class Codes: H05K 2201/10106 Light emitting diode [LED]
• CPC Class Codes: H05K 3/321 by conductive adhesives
• CPC Class Codes: Y10S 362/80 : Light emitting diode

Abstract

A method of manufacturing an electrically driven L.E.D. lamp assembly (10) comprising the steps of screen printing an electrically insulating coating (16) which can be of less than two hundred microns thickness over an electrically and thermally conductive heat sink, i.e., aluminum, and printing circuit traces 18 of a resin with metal dispersed therein in end to end relationship on the routes of insulating coating 16 to establish discrete and electrically conductive paths for electrically interconnecting light emitting diodes 20. The light emitting diodes 20 are adhesively secured to the ends of adjacent circuit traces 18 with an electrically conductive adhesive 26 comprising an organic polymeric material compounded with a metal.

Claims

1. A method of manufacturing an electrically driven L.E.D. lamp assembly (10) comprising the steps of;

disposing an electrically insulating coating (16) of less than one thousand microns thickness over an electrically and thermally conductive and entirely metal heat sink (12),

printing circuit traces (18) on the coating (16) to establish discrete and electrically conductive paths for electrically interconnecting light emitting diodes (20), and

adhesively securing light emitting diodes (20) to the circuit traces (18) with an electrically and thermally conductive adhesive (26).

2. A method as set forth in claim 1 further defined as forming the electrically insulating coating (16) with a thickness of less than two hundred microns.

3. A method as set forth in claim 1 further defined as forming the electrically insulating coating (16) on an aluminum heat sink (12).

4. A method as set forth in claim 1 further defined as forming the electrically insulating coating (16) on the heat sink (12) by screen printing.

5. A method as set forth in claim 1 further defined as forming the electrically insulating coating (16) on the heat sink (12) by using a thixotropic material and curing the material into a smooth homogeneous coating.

6. A method as set forth in claim 1 further defined as forming the electrically insulating coating (16) on the heat sink (12) by dipping the heat sink into a liquid material and curing the material into the coating (16).

7. A method as set forth in claim 1 further defined as forming the electrically insulating coating (16) on an aluminum heat sink (12) by anodizing the aluminum to form an aluminum oxide coating.

8. A method as set forth in claim 1 further defined as printing circuit traces (18) on the electrically insulating coating (16) by screen printing.

9. A method as set forth in claim 1 further defined as further defined as printing circuit traces (18) with a polymeric material having metal particles dispersed therein.

10. A method as set forth in claim 1 further defined as printing circuit traces (18) with an epoxy compounded with a noble metal.

11. A method as set forth in claim 1 further defined as printing circuit traces (18) with an epoxy compounded with one of silver and gold.

12. A method as set forth in claim 1 further defined as printing circuit traces (18) with a phenolic resin compounded with one of copper and nickel.

13. A method as set forth in claim 1 further defined as adhesively securing light emitting diodes (20) to the circuit traces (18) by depositing small patches of the electrically conductive adhesive (26) at spaced positions on the circuit traces (18).

14. A method as set forth in claim 13 further defined as simultaneously depositing the leads of an array of light emitting diodes (20) into registry with the patches.

15. A method as set forth in claim 13 further defined as stenciling the patches of adhesive (26) onto the circuit traces (18).

16. A method as set forth in claim 1 further defined as adhesively securing light emitting diodes (20) to the circuit traces (18) by depositing an electrically conductive adhesive (26) comprising an organic polymeric material compounded with a metal.

17. A method as set forth in claim 1 further defined as forming heat radiating fins on the heat sink (12).

18. A method as set forth in claim 1 further defined as disposing the electrically insulating coating (16) only along predetermined routes to leave open areas therebetween, and printing the conductive traces (18) in predetermined spaced lengths within and spaced from the edges of the routes to prevent electrical conduction between traces (18) and from the traces (18) to the heat sink (12).

19. A method as set forth in claim 1 further defined as curing the adhesive (26) while subjecting the leads of the light emitting diodes (20) to a temperature of less than 100°

C.

20. A method of manufacturing an electrically driven L.E.D. lamp assembly (10) comprising the steps of;

screen printing an electrically insulating coating (16) of less than three hundred microns thickness over an electrically and thermally conductive and a homogenous aluminum heat sink (12),

printing circuit traces (18) with a phenolic resin compounded with one of copper, silver and nickel on the coating (16) to establish discrete and electrically conductive paths for electrically interconnecting light emitting diodes (20), and

adhesively securing light emitting diodes (20) to the circuit traces (18) with an electrically and thermally conductive adhesive (26) comprising an organic polymeric material compounded with a metal.

21. An electrically driven L.E.D. lamp assembly comprising:

an electrically and thermally conductive and entirely metal heat sink (12);

an electrically insulating coating (16) over said electrically and thermally conductive heat sink (12), and being less than one thousand microns in thickness;

circuit traces (18) disposed in predetermined spaced lengths along said coating (16) to prevent electrical conduction between said traces (18) and from said traces (18) to said heat sink (12);

a plurality of light emitting diodes (20) having electrical leads; and

an electrically conductive adhesive (26) securing said leads of said light emitting diodes (20) to adjacent ones of said circuit traces (18).

22. An assembly as set forth in claim 21 wherein said heat sink is made of homogeneous aluminum.

23. An assembly as set forth in claim 21 wherein said adhesive comprises an organic polymeric material compounded with a metal.

24. An assembly as set forth in claim 21 including heat radiating fins on said heat sink (12).

25. An assembly as set forth in claim 21 wherein said coating (16) is disposed only along predetermined routes having edges to define open areas between said edges of said routes;

and said traces disposed between said edges of said routes.