HEAT-SINK/CONNECTOR SYSTEM FOR LIGHT EMITTING DIODE

• US 20130265782A1
• Filed: 12/14/2011
• Published: 10/10/2013
• Est. Priority Date: 12/15/2010
• Status: Active Grant

• Current Assignee: Illinois Tool Works Inc.
• Original Assignee: Illinois Tool Works Inc.
• Inventors: Barrena, Juan J., Claprood, Edward J., Larson, Eric K.
• Granted Patent: US 9,194,573 B2
• Time in Patent Office: Days
• US Class Current: 362/373
• 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: F21V 17/00 Fastening of component parts of lighting devices, e.g. shades, globes, refractors, reflectors, filters, screens, grids or protective cages of light sources or light holders F21V19/00
• CPC Class Codes: F21V 17/16 by deformation of parts; Snap action mounting
• CPC Class Codes: F21V 17/164 the parts being subjected to bending, e.g. snap joints
• CPC Class Codes: F21V 29/70 characterised by passive heat-dissipating elements, e.g. heat-sinks
• CPC Class Codes: F21Y 2115/10 Light-emitting diodes [LED]
• CPC Class Codes: H01L 2224/48091 Arched
• 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: Y10T 29/49128 Assembling formed circuit to base

Abstract

An assembly for high-powered LEDs provides a direct attachment of the LED to a ceramic thermal conductor/electrical insulator sealed in a housing with a compression element between a portion of the housing and ceramic heat sink to provide a predetermined range of biasing force locating the ceramic heat sink against the portion of the housing with dimensional changes in the ceramic heat sink caused by thermal expansion of the ceramic heat sink.

Claims

1. An LED assembly comprising:

an LED dissipating during operation at least 500 mW;

a ceramic heat sink providing a first surface supporting the LED and in thermal communication with the LED;

a first and second conductor in electrical communication with the LED;

a sealed housing receiving the ceramic heat sink and LED therein, the sealed housing having a first portion fitting over the LED to permit the passage of light therethrough and a second portion providing for sealed ingress of the first and second electrical conductors through a housing wall for providing power to the LED; and

a compression element extending between a portion of the housing and ceramic heat sink to provide a predetermined range of biasing force locating the ceramic heat sink against the portion of the housing with dimensional changes in the ceramic heat sink caused by thermal expansion of the ceramic heat sink.

2. The LED assembly of claim 1 wherein the first portion of the sealed housing is a light transmissive thermoplastic and the second portion of the sealed housing is a thermoplastic fused to the first portion.

3. The LED assembly of claim 2 wherein the electrical conductors provide integral coaxial thermoplastic insulation and where the second portion of the sealed housing is fused to the thermoplastic insulation.

4. The LED assembly of claim 1 wherein the spring clamp is a flexible metal ring.

5. The LED assembly of claim 4 wherein the first portion of the sealed housing provides a ledge abutting a portion of the first surface of the ceramic heat sink and a collar extending around a portion of the ceramic heat sink behind the first surface and wherein the spring clamp includes cantilevered teeth portions providing a wedging engagement with an inner surface of the collar to hold the flexible metal ring in abutment with a second surface of ceramic heat sink behind the first surface.

6. The LED assembly of claim 5 wherein the metal ring further includes protrusions contacting the second surface and limiting the force applied thereto.

7. The LED assembly of claim 1 wherein the first surface includes metal traces attached directly to the first surface and electrically communicating between the LED and first and second conductors.

8. The LED assembly of claim 7 wherein the metal traces are printed conductive ink.

9. The LED assembly of claim 1 wherein the ceramic is Steatite.

10. The LED assembly of claim 1 wherein the first surface includes conductive traces attached directly to the first surface;

and further including

a first and second spring clamp insertable through apertures in the ceramic heat sink and each having first portions contacting different conductive traces when so inserted and clamping elements receiving and retaining different of the first and second conductors.

11. The LED assembly of claim 10 wherein the first portion is spring biased by the spring clamp against the conductive trace.

12. The LED assembly of claim 10 wherein the metal traces are printed conductive ink.

13. The LED assembly of claim 2 wherein the clamping elements provide flexible opposed spring elements slidably receiving ends of the conductors in electrical engagement.

14. The LED assembly of claim 1 wherein the ceramic is Steatite.

15. A method of fabricating an LED assembly including:

an LED dissipating during operation at least 500 mW;

a ceramic heat sink providing a first surface supporting the LED in thermal communication with the LED;

a first and second conductor in electrical communication with the LED;

a sealed housing receiving the ceramic heat sink and LED therein, the sealed housing having a first portion fitting over the LED to permit the passage of light therethrough and a second portion providing for sealed ingress of the first and second electrical conductors through a housing wall for providing power to the LED; and

a compression element extending between a portion of the housing and ceramic heat sink to provide a predetermined range of biasing force pressing the ceramic heat sink against the portion of the housing with dimensional changes in the ceramic heat sink caused by thermal expansion of the ceramic heat sink;

the method comprising the steps of;

(a) attaching the LED to the first surface of the ceramic heat sink;

(b) fitting the assembled LED and ceramic heat sink into one the first portion of the housing and retaining the ceramic heat sink in the first portion with the spring clamp;

(c) overmolding the first portion and the conductors with a thermoplastic material providing the second portion of the housing providing a sealed volume holding the ceramic substrate and LED.

16. The method of claim 15 wherein the step of attaching the LED to the first surface of the ceramic heat sink includes the step of applying a printed conductor to the first surface of the ceramic heat sink and attaching the LED thereto.

17. The method of claim 15 wherein the ceramic heat sink further supports electrically conductive traces communicating with the LED and including the step of:

inserting a first and second spring clamp through apertures in the ceramic heat sink each having first portions contacting different conductive traces when so inserted and clamping element receiving and retaining different electrical wires;

attaching the conductors to the clamping elements to provide electrical connection between the conductors and the LED.

18. The method of claim 15 wherein the first portion of the sealed housing provides a ledge abutting a portion of the first surface of the ceramic heat sink and a collar extending around a portion of the ceramic heat sink behind the first surface and including the step of press fitting the spring clamp into engagement with an inner surface of the collar and a second surface of ceramic heat sink behind the first surface.