Methods of integrating LED chips with heat sinks, and LED-based lighting assemblies made thereby

• US 8,981,629 B2
• Filed: 03/13/2013
• Issued: 03/17/2015
• Est. Priority Date: 08/26/2008
• Status: Active Grant

• Current Assignee: Current Lighting Solutions, LLC (f/k/a GE Lighting Solutions, LLC) (American Industrial Partners)
• Original Assignee: Albeo Technologies (Savant Systems, LLC)
• Inventors: Kong, Ming, Powell, John, Bisberg, Jeffrey
• Primary Examiner(s): HINES, ANNE M
• Application Number:
  US13/802,401
• Publication Number:
  US 20140125213A1
• Time in Patent Office: 734 Days
• Field of Search: 313/46, 313498-512
• US Class Current: 313/46
• CPC Class Codes: F21V 29/70 characterised by passive heat-dissipating elements, e.g. heat-sinks
• CPC Class Codes: H01L 2224/2919 with a principal constituent of the material being a polymer, e.g. polyester, phenolic based polymer, epoxy
• CPC Class Codes: H01L 2224/2929 with a principal constituent of the material being a polymer, e.g. polyester, phenolic based polymer, epoxy
• CPC Class Codes: H01L 2224/29339 Silver [Ag] as principal constituent
• CPC Class Codes: H01L 2224/32245 the item being metallic
• CPC Class Codes: H01L 2224/45124 Aluminium (Al) as principal constituent
• CPC Class Codes: H01L 2224/45144 Gold (Au) as principal constituent
• CPC Class Codes: H01L 2224/48091 Arched
• CPC Class Codes: H01L 2224/48137 the bodies being arranged next to each other, e.g. on a common substrate
• CPC Class Codes: H01L 2224/48227 connecting the wire to a bond pad of the item
• CPC Class Codes: H01L 2224/48465 the other connecting portion not on the bonding area being a wedge bond, i.e. ball-to-wedge, regular stitch
• CPC Class Codes: H01L 2224/73265 Layer and wire connectors
• CPC Class Codes: H01L 2224/8592 Applying permanent coating, e.g. protective coating
• CPC Class Codes: H01L 23/13 characterised by the shape
• CPC Class Codes: H01L 23/367 Cooling facilitated by shape of device H01L23/38, H01L23/40, H01L23/42, H01L23/44, H01L23/46 take precedence
• CPC Class Codes: H01L 24/29 of an individual layer connector
• CPC Class Codes: H01L 24/32 of an individual layer connector
• CPC Class Codes: H01L 24/45 of an individual wire connector
• CPC Class Codes: H01L 24/48 of an individual wire connector
• CPC Class Codes: H01L 24/73 Means for bonding being of different types provided for in two or more of groups H01L24/10, H01L24/18, H01L24/26, H01L24/34, H01L24/42, H01L24/50, H01L24/63, H01L24/71
• CPC Class Codes: H01L 25/0753 : the devices being arranged next to each other
• 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 2924/0665 : Epoxy resin
• CPC Class Codes: H01L 2924/12041 : LED
• CPC Class Codes: H01L 33/54 : having a particular shape
• CPC Class Codes: H01L 33/58 : Optical field-shaping elements
• CPC Class Codes: H01L 33/62 : Arrangements for conducting electric current to or from the semiconductor body, e.g. lead-frames, wire-bonds or solder balls
• CPC Class Codes: H05K 1/056 : the metal substrate being covered by an organic insulating layer

Abstract

An LED-based lighting assembly includes a heat sink having at least one pedestal with an upwardly facing, upper planar surface that is raised in a vertical direction relative to an upwardly facing, lower planar surface of the heat sink. A PCB forms an aperture corresponding to the pedestal, includes electrical conductors on an upper surface thereof, and is attached to the lower planar surface. The upper planar surface extends into the aperture, and one or more LED chips attach directly to the upper planar surface and connect to the conductors such that light emits upwardly. A method of integrating LEDs with a heat sink includes mounting a PCB to a planar surface of the heat sink, mounting one or more LED chips to a raised surface of the heat sink that is not covered by the PCB, and electrically connecting the LED chips to conductors on the PCB.

Claims

1. A light emitting diode (LED)-based lighting assembly, comprising:

a heat sink having at least one pedestal integrally formed therewith, the pedestal including an upwardly facing, upper planar surface that is raised in a vertical direction relative to an upwardly facing, lower planar surface of the heat sink;

a printed circuit board (PCB) forming an aperture therein corresponding to the pedestal, the PCB including electrical conductors on an upper surface thereof, the PCB being attached to the lower planar surface such that the upper planar surface extends into the aperture; and

one or more LED chips attached directly to the upper planar surface and electrically connected to the conductors such that light from the one or more LED chips emits upwardly from the upper planar surface;

wherein the pedestal has a height such that the combined height of the pedestal and the one or more LED chips thereon matches a thickness of the PCB.

2. The lighting assembly of claim 1, wherein the heat sink comprises a base portion that includes the pedestal on an upwardly facing first side thereof, and at least two fins integrally formed with a downwardly facing second side thereof, the fins extending downwardly from the second side.

3. The lighting assembly of claim 2, each of the fins having an aspect ratio of at least 2:

1 with a major dimension of each fin extending in the vertical direction.

4. The lighting assembly of claim 3, each of the fins having an aspect ratio of at least 5:

1.

5. The lighting assembly of claim 2, the pedestal and the fins being integrally formed with the base member as an extrusion.

6. The lighting assembly of claim 1, wherein the heat sink comprises an outer surface counterfacing the upper planar and lower planar surfaces, the outer surface forming an interface to ambient air for dissipating heat generated by the one or more LED chips.

7. The lighting assembly of claim 1, wherein the heat sink comprises a material having a bulk thermal conductivity of at least 15 W/(m°

K).

8. The lighting assembly of claim 1, wherein the heat sink comprises a material having a bulk thermal conductivity of at least 100 W/(m°

K).

9. The lighting assembly of claim 1, further comprising a first encapsulation material that covers each of the pedestals and each of the one or more LED chips.

10. The lighting assembly of claim 9, further comprising a second encapsulation material that covers bond wires that electrically connect each of the one or more LED chips to the conductors.

11. The lighting assembly of claim 1, wherein each of the one or more LED chips comprises an electrically nonconductive substrate and is attached directly to the pedestal with an electrically nonconductive adhesive.

12. The lighting assembly of claim 11, the electrically nonconductive substrate comprising a ceramic.

13. The lighting assembly of claim 12, the electrically nonconductive substrate comprising alumina.

14. The lighting assembly of claim 1, wherein each of the one or more LED chips is formed on an electrically conductive substrate and is attached directly to the pedestal with an electrically conductive adhesive.

15. The lighting assembly of claim 1, the PCB comprising at least one reflective surface at the aperture, such that light from the one or more LED chips that reaches the reflective surface reflects from the PCB.

16. The lighting assembly of claim 15, the reflective surface forming a non-vertical slope such that the light from the one or more LED chips that reaches the reflective surface reflects upwardly.

17. The lighting assembly of claim 1, the pedestal further forming a non-vertical surface adjacent to the upper planar surface that slopes upwardly as it extends away from the upper planar surface, such that light from the one or more LED chips that reaches the non-vertical surface reflects upwardly.

18. The lighting assembly of claim 1, the aperture and pedestal being closely matched in dimensions such that the PCB is within one millimeter of the pedestal on all sides.

19. A light emitting diode (LED)-based lighting assembly, comprising:

a heat sink having at least one pedestal integrally formed therewith, the pedestal including an upwardly facing, upper planar surface that is raised in a vertical direction relative to an upwardly facing, lower planar surface of the heat sink;

a printed circuit board (PCB) forming an aperture therein corresponding to the pedestal, the PCB including electrical conductors on an upper surface thereof, the PCB being attached to the lower planar surface such that the upper planar surface extends into the aperture;

one or more LED chips attached directly to the upper planar surface and electrically connected to the conductors such that light from the one or more LED chips emits upwardly from the upper planar surface; and

a first encapsulation material that covers each of the pedestals and each of the one or more LED chips;

wherein the PCB acts as a dam to contain the first encapsulation material during dispense of the encapsulation material.

20. The lighting assembly of claim 19, wherein the first encapsulation material comprises one or more of silicone, epoxy and acrylic.

21. The lighting assembly of claim 19, wherein the first encapsulation material is admixed with a phosphor.