LED DEVICE WITH FLEXIBLE THERMAL INTERFACE

Abstract

The present invention relates to a LED device at least comprising a LED module with one or several LEDs mounted on a carrier, a heat sink or heat spreader and a thermal interface between the carrier and the heat sink. The carrier is thermally connected via the thermal interface to the heat sink. The thermal interface is formed of a member of a heat-conducting material, which is ductile at least during assembling of the device and allows to arrange the heat sink in orientation and position substantially independent from the carrier. The proposed LED device allows for flexible design solutions of the thermal components as well as the overall design, e. g. for applications in automotive lighting.

Claims

1. A method for providing a LED device of flexible design, the LED device at least comprising a LED module with one or several light emitting diodes mounted on a carrier, a heat sink or heat spreader, and a thermal interface between the carrier and the heat sink or heat spreader, said carrier being thermally connected via the thermal interface to the heat sink or heat spreader, the method comprising the steps of: providing the one or several light emitting diodes and the carrier; aligning the carrier and the one or several light emitting diodes according to an optical referencing of the LED device's design; providing the heat sink or heat spreader in a form according to the LED device's design; providing the thermal interface in the form of a member of a heat conducting material, which is ductile at least during assembling but maintains its position and shape after assembling; and aligning and assembling the carrier and the heat sink or heat spreader by means of the thermal interface with the positions of the carrier and of the heat sink or heat spreader being determined independent from each other according to the LED device's design.

2. The method according to claim 1, characterized in that the member is formed of a material which gets rigid or is made rigid after assembling of the device.

3. The method according to claim 2, characterized in that the member is formed of a solid foam or a solid bulk material.

4. The method according to claim 1, characterized in that the member is formed of a flexible metal.

5. The method according to claim 4, characterized in that the member has a spring-like shape.

6. The method according to claim 1, characterized in that the member is formed of a metal mesh.

7. The method according to claim 1, characterized in that the heat sink or heat spreader is formed of a compact solid material.

8. The method according to claim 1, further comprising the steps of: providing an optical system; and integrating and aligning the optical system with the one or several light emitting diodes or the carrier.

9. (canceled)

10. The method according to claim 8, characterized in that the optical system includes one or more reflectors.

11-13. (canceled)

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0012] The proposed LED device is described in the following by way of examples in connection with the accompanying figures. The figures show:

[0013] FIG. 1 a first example of a LED module on a heat sink according to the present invention;

[0014] FIG. 2 a second example of a LED module on a heat sink according to the present invention;

[0015] FIG. 3 a third example of a LED module on a heat sink according to the present invention;

[0016] FIG. 4 a fourth example of a LED module on a heat sink according to the present invention; and

[0017] FIG. 5 an example showing the assembling of a LED device according to the present invention in an automotive lamp from a) to d).

DETAILED DESCRIPTION OF EMBODIMENTS

[0018] FIG. 1 shows a cross sectional schematic view of a first example of the proposed LED device in which the LED module 1 is thermally connected via a thermal interface 4 to a heat sink 5. Although not shown in the figures, such a LED module also comprises one or several electrical connection pads for electrically connecting the LEDs. In this example the thermal interface 4 is formed of a spring like metallic member 8 between the carrier 3 of the module 1, on which the LED 2 is mounted, and the heat sink 5. The use of such a spring like member 8 for the thermal interface 4 has the possibility to appropriately bend this member so that the carrier 3 and the heat sink 5 can be flexibly positioned and oriented to one another and still maintain a good thermal connection between one another.

[0019] The example of FIG. 2 shows a cross sectional schematic view of a second example in which a heat conductive metal mesh 9 is placed between the carrier 3 and the heat sink 5. This flexible mesh 9 allows an independent positioning and orienting of the module 1 or carrier 3 and the heat sink 5 from one another. The mesh 9 fills the volume between both components to achieve the appropriate thermal connection.

[0020] FIGS. 3 and 4 show further examples in which the thermal interface 4 is formed of a voluminous material, in particular a solid heat-conductive foam 10, which is ductile during the assembling of the device. The heat conductive ductile foam is placed between the carrier 3 and the heat sink 5 at the time of assembling. This also allows an independent positioning and orienting of the module 1 or carrier 3 and the heat sink 5 from one another. The foam fills the volume between both components to achieve the appropriate thermal connection. After applying the foam and adjusting both components as appropriate, the foam then gets rigid automatically or is cured, e. g. by UV curing, after assembling. As shown in FIGS. 3 and 4 such a foam adapts to the rough surface of the heat sink 5 due to its ductility at the time of application.

[0021] FIG. 5 shows an example of assembling four LED modules 1 in a reflector 6 of an automotive lamp. In this case, as shown in FIG. 5a, the four modules 1 formed of the carrier 3 and the LED 2 have to be mounted in the corresponding four reflector components. A common heat sink 5 has to be thermally connected to the four LED modules 1. The heat sink 5 has its own mechanical fixation and can be mounted independently from the mechanical fixation and references of the LED modules 1 in the reflector components. In FIG. 5b the mounting of the LED modules 1 to the reflector components are made for good optical referencing. After this mounting the heat sink 5 has to be connected to the LED modules 1. FIG. 5c shows the positioning of the heat sink 5 close to the LED modules 1. Without any further thermal interface, an air gap 7 would arise between one of the modules and the heat sink 5 as shown in FIG. 5c. Using the flexible thermal interface 4 according to the present invention, the heat sink 5 can be connected with good thermal connection to all LED modules 1 independent of the actual position and orientation of the heat sink 5 relative to the LED modules 1 as shown in FIG. 5d. The thermal interface 4 is formed only once, e. g. it will become rigid and maintain its position and shape after assembling of the automotive lamp in order to provide the thermal contact. As the heat sink alignment is separated from the mechanical referencing of the optical system to the LED modules 1, no compromise between styling freedom and thermal performance has to be made.

[0022] While the invention has been illustrated and described in detail in the drawings and forgoing description, such illustration and description are to be considered illustrative or exemplary and not restrictive. The invention is not limited to the disclosed embodiments. Other variations to the disclosed embodiments can be understood and effected by those skilled in the art in practicing the claimed invention, from a study of the drawings, the disclosure and the appended claims. In the claims the word “comprising” does not exclude other elements or steps, and the indefinite article “a” or “an” does not exclude a plurality. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage. Any reference signs in the claims should not be construed as limiting the scope of the invention.

LIST OF REFERENCE SIGNS

[0023] 1 LED module [0024] 2 LED [0025] 3 carrier [0026] 4 thermal interface [0027] 5 heat sink [0028] 6 reflector [0029] 7 air gap [0030] 8 spring like metallic member [0031] 9 metal mesh [0032] 10 solid foam