GB2510865A - Method for manufacturing a lighting unit and lighting unit - Google Patents

Method for manufacturing a lighting unit and lighting unit Download PDF

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Publication number
GB2510865A
GB2510865A GB1302692.7A GB201302692A GB2510865A GB 2510865 A GB2510865 A GB 2510865A GB 201302692 A GB201302692 A GB 201302692A GB 2510865 A GB2510865 A GB 2510865A
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GB
United Kingdom
Prior art keywords
solid state
heat sink
electrically conductive
lighting device
state lighting
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
GB1302692.7A
Other versions
GB2510865B (en
GB201302692D0 (en
Inventor
Justin Maeers
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Collingwood Lighting Ltd
Original Assignee
Collingwood Lighting Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Collingwood Lighting Ltd filed Critical Collingwood Lighting Ltd
Priority to GB1302692.7A priority Critical patent/GB2510865B/en
Publication of GB201302692D0 publication Critical patent/GB201302692D0/en
Publication of GB2510865A publication Critical patent/GB2510865A/en
Application granted granted Critical
Publication of GB2510865B publication Critical patent/GB2510865B/en
Active legal-status Critical Current
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Classifications

    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B33/00—Electroluminescent light sources
    • H05B33/10—Apparatus or processes specially adapted to the manufacture of electroluminescent light sources
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L24/00—Arrangements for connecting or disconnecting semiconductor or solid-state bodies; Methods or apparatus related thereto
    • H01L24/80—Methods for connecting semiconductor or other solid state bodies using means for bonding being attached to, or being formed on, the surface to be connected
    • H01L24/83—Methods for connecting semiconductor or other solid state bodies using means for bonding being attached to, or being formed on, the surface to be connected using a layer connector
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L24/00—Arrangements for connecting or disconnecting semiconductor or solid-state bodies; Methods or apparatus related thereto
    • H01L24/01—Means for bonding being attached to, or being formed on, the surface to be connected, e.g. chip-to-package, die-attach, "first-level" interconnects; Manufacturing methods related thereto
    • H01L24/26—Layer connectors, e.g. plate connectors, solder or adhesive layers; Manufacturing methods related thereto
    • H01L24/28—Structure, shape, material or disposition of the layer connectors prior to the connecting process
    • H01L24/29—Structure, shape, material or disposition of the layer connectors prior to the connecting process of an individual layer connector
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L33/00—Semiconductor devices with at least one potential-jump barrier or surface barrier specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L33/48—Semiconductor devices with at least one potential-jump barrier or surface barrier specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by the semiconductor body packages
    • H01L33/64—Heat extraction or cooling elements
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K1/00—Printed circuits
    • H05K1/02—Details
    • H05K1/0201—Thermal arrangements, e.g. for cooling, heating or preventing overheating
    • H05K1/0203—Cooling of mounted components
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K3/00—Apparatus or processes for manufacturing printed circuits
    • H05K3/30—Assembling printed circuits with electric components, e.g. with resistor
    • H05K3/32—Assembling printed circuits with electric components, e.g. with resistor electrically connecting electric components or wires to printed circuits
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
    • C25D11/00—Electrolytic coating by surface reaction, i.e. forming conversion layers
    • C25D11/02—Anodisation
    • C25D11/04—Anodisation of aluminium or alloys based thereon
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F21—LIGHTING
    • F21V—FUNCTIONAL FEATURES OR DETAILS OF LIGHTING DEVICES OR SYSTEMS THEREOF; STRUCTURAL COMBINATIONS OF LIGHTING DEVICES WITH OTHER ARTICLES, NOT OTHERWISE PROVIDED FOR
    • F21V29/00—Protecting lighting devices from thermal damage; Cooling or heating arrangements specially adapted for lighting devices or systems
    • F21V29/50—Cooling arrangements
    • F21V29/70—Cooling arrangements characterised by passive heat-dissipating elements, e.g. heat-sinks
    • F21V29/74—Cooling arrangements characterised by passive heat-dissipating elements, e.g. heat-sinks with fins or blades
    • F21V29/75—Cooling arrangements characterised by passive heat-dissipating elements, e.g. heat-sinks with fins or blades with fins or blades having different shapes, thicknesses or spacing
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F21—LIGHTING
    • F21Y—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES F21K, F21L, F21S and F21V, RELATING TO THE FORM OR THE KIND OF THE LIGHT SOURCES OR OF THE COLOUR OF THE LIGHT EMITTED
    • F21Y2115/00—Light-generating elements of semiconductor light sources
    • F21Y2115/10—Light-emitting diodes [LED]
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    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K2203/00—Indexing scheme relating to apparatus or processes for manufacturing printed circuits covered by H05K3/00
    • H05K2203/14—Related to the order of processing steps
    • H05K2203/1461—Applying or finishing the circuit pattern after another process, e.g. after filling of vias with conductive paste, after making printed resistors
    • H05K2203/1469—Circuit made after mounting or encapsulation of the components
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K3/00—Apparatus or processes for manufacturing printed circuits
    • H05K3/10—Apparatus or processes for manufacturing printed circuits in which conductive material is applied to the insulating support in such a manner as to form the desired conductive pattern
    • H05K3/12—Apparatus or processes for manufacturing printed circuits in which conductive material is applied to the insulating support in such a manner as to form the desired conductive pattern using thick film techniques, e.g. printing techniques to apply the conductive material or similar techniques for applying conductive paste or ink patterns
    • H05K3/1216—Apparatus or processes for manufacturing printed circuits in which conductive material is applied to the insulating support in such a manner as to form the desired conductive pattern using thick film techniques, e.g. printing techniques to apply the conductive material or similar techniques for applying conductive paste or ink patterns by screen printing or stencil printing
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K3/00—Apparatus or processes for manufacturing printed circuits
    • H05K3/44—Manufacturing insulated metal core circuits or other insulated electrically conductive core circuits

Abstract

A method for manufacturing a lighting unit includes providing at least a first solid state lighting device 401a such as an LED; providing a heat sink 413 such as an extruded aluminium body, wherein at least a part 413a of the heat sink is non-electrically conductive (e.g. anodised); attaching the first solid state lighting device to the non-electrically conductive part of the heat sink using a curable material 419 such as a resin material that contains silver particles, the curable material being an electrically conductive material when in a cured state; and curing the curable material thereby fixing the first solid state lighting device to the heat sink, the arrangement being such that at least some of the heat generated in use by the first solid state lighting device is thermally conducted to the heat sink through the cured material. A lighting unit made by the method is also disclosed.

Description

Method For Manufacturing A Lighting Unit And Lighting Unit The present invention relates to a method for manufacturing a lighting unit and a lighting unit.
Light Emitting Diode (LED) lighting units, which are a type of solid state lighting device, generate a lot of heat during use. The heat generated can affect the performance of the LEDs and their longevity and therefore in many applications it is desirable to remove the heat from the LEDs using a heat sink.
For known lighting units, such as LED downlights, there are several established methods for mounting LED devices onto the heat sink, each of which provide a characteristic LED lighting unit structure.
For example, a first common structure is shown in Figure 1. The LED devices 1, which each include a thermal pad, are soldered 3 onto a Printed Circuit Board (PCB) 5. The PCB includes an FR4 (glass reinforced epoxy resin) base material 7, an upper copper layer 9, a lower copper layer 11, and copper plated through holes (known as vias) 10. The LED devices 3 are soldered 3 onto the upper copper layer 9.
This arrangement is then mounted onto a thermally conductive heat sink (not shown).
The upper copper layer 9 acts as a heat spreader, spreading the heat throughout the whole top surface of the PCB 5. The FR4 base material 7 acts as a dielectric layer. This layer is required to be electrically isolating, however due to its material properties is extremely heat insulating thereby preventing the efficient conduction of heat through the system. The copper plated vias 10 act as a heat passage through the dielectric material 7 to the base copper layer 11.
It can be seen that there are only a limited number of vias 10 that are available to transfer heat to the lower copper layer 11, which reduces the thermal efficiency of this arrangement, and that there are a relatively large number of thermal boundaries (a boundary is where there two components meet, typically having different materials) for the heat to traverse in order to arrive at the heat sink. Furthermore the vias 10 are an expensive feature to manufacture.
A second prior art arrangement is shown in Figure 2. The LED devices 101, which each include a thermal pad, are soldered 103 onto a Metal Clad Printed Circuit Board (MCPCB) 105. The MCPCB 105 includes an upper copper pad 109, a dielectric layer 107, and aluminium (or other thermally conductive material, such as copper or ceramic) base material 111. The LED devices 101 are soldered 103 onto the upper copper pad 109. The upper copper pad 109 is fixed to the dielectric layer 107, which thermally and electrically insulates the base material 111 from the electrical connection to the LED devices 101 and also prevents an efficient heat transfer. The dielectric layer 107 is fixed to the thermally conductive base material 111.
The aluminium base layer 111 acts as a heat spreader, spreading the heat throughout the whole MCPCB 105. The MCPCB 105 is mounted onto a heatsink not shown), and heat is transferred by conduction from the MCPCB 105 to the heat sink to be dissipated to free air.
A third prior art arrangement is shown in Figure 3. The third prior art arrangement includes LED devices 201, a PCB 205 having a thermally conductive base material 211 that is not electrically conductive (e.g. a thermally conductive ceramic), solder 203, and an electrically conductive layer 209.
The electrically conductive layer 209 is screen printed onto a non-electrically conductive surface 211 of the PCB 205. The solder 203 is screen printed onto the electrically conductive layer 209. The LED devices 201, which each include a thermal pad, are soldered to the conductive paste layer 209 via a reflow solder 203 process. This involves placing the LED devices 201 onto the printed solder 203 and then placing the arrangement into an oven, which is heated to the melting point of the solder 203to enable the solder 203 to reflow. When the process is completed the LED devices 201 are bonded to the electrically and thermally conductive layer 209 by the solder 203.
In use, heat generated by the LED devices 201 is conducted by the solder 203 to the conductive layer 209. In turn, the thermally conductive layer 209, transfers the heat to the thermally conductive base material 211, which dissipates it across its surface to a heat sink (not shown) in order to dissipate the heat to free air.
When an electric current is passed through an LED, some of the energy is converted to light and some into heat at the junction point within the LED; this raises the temperature within the LED (the measurement of the temperature at this point is commonly referred to as the junction temperature (Tj). Keeping the Tj as low as possible is critical to the longevity and light output of the LED. The Tj is affected by the thermal conductivity of the materials that the heat passes through, and the thermal resistance caused by boundaries where surfaces of these material meet. Generally, the more boundaries that are present, the higher the thermal resistance and therefore the higher the Tj will be, which is undesirable.
For the prior art arrangements mentioned above, the PCB is fixed to the heat sink with a mechanical connection. The LED is mechanically, electrically and thermally connected to the light engine with solder, and from there by various thermal routes to the heat sink.
A fourth prior art arrangement is shown in Figures 4a and 4b. The fourth prior art arrangement tries to address some of the above-mentioned disadvantages by mounting the LED devices 301, which each include a thermal pad, onto a thermally conductive heat sink 313 without using a PCB. Instead, a first layer 307 of a non-electrically conductive paste is screen printed onto the heat sink 313. Then electrically conductive paste 309 is screen printed onto the non-electrically conductive paste 307, to form electrical connections between the LED devices 301. A second layer of a non-electrically conductive paste (not shown) is then printed over the electrically conductive paste 309 to act as a solder resist.
The LED devices 301 are then mechathcally, thermally and electrically attached by a reflow solder process 303.
However, the inventors have realised that ifirther material savings, improved thermal efficiency and a reduction in the number of manufacturing process steps used can be achieved by modifying the fourth prior art arrangement and the manufacturing process.
Accordingly the present invention seeks to provide a method for manufacturing a lighting unit and a lighting unit that mitigates at least one of the aforementioned problems, or at least provides an alternative to existing apparatus and methods.
According to one aspect of the invention there is provided a method for manufacturing a lighting unit according to claim 1.
The inventors have developed an improved manufacturing process and a lighting unit derived therefrom, by realising that they can make use of a pre-existing non-electrically conductive part of the heat sink to reduce the number of thermal boundaries in the lighting unit structure, and thereby reducing the number of manufacturing steps required to produce the structure. The curing process bonds the first solid state lighting device directly to a non-electrically conductive part of the heat sink, without requiring the use of solder. This provides a very simple and thermally efficient connection between the heat sink and the solid state lighting devices, and reduces the number of manufacturing steps when compared with prior art methods. This enables the lighting unit produced by the manufacturing process to transfer heat more effectively to the environment, which improves the operating performance of the or each solid state lighting device and improves its longevity. Having a simplified manufacturing process saves on cost and reduces the amount of materials required to provide the lighting unit, which is important for mass produced lighting units.
The curable material provides direct mechanical, thermal and electrical attachment of the or each solid state lighting device to the heat sink. This removes the need for a separate PCB and reduces the thermal resistance between the or each solid state lighting device and the heat sink, thereby lowering the junction temperature of the or each solid state lighting device in operation. This results in improved thermal management and significant cost savings as a result of reduced material usage and labour.
Advantageously the method can include applying the electrically conductive curable material to at least one of the heat sink and the or each solid state lighting device by a printing process, and preferably a screen printing process. In preferred embodiments the curable material is applied to the heat sink. Using a printing process enables portions of the electrically curable material that are primarily for mechanically and thermally attaching the solid state lighting devices to the heat sink to be applied to the heat sink at the same time as those portions of the electrically conductive curable material that are used primarily to form electrical connections, for example between the solid state lighting devices.
The curable material can include electrically and/or thermally conductive particles. The curable material can include metal such as at least one of silver, copper, platinum and gold particles. The curable material can include a non-metal such as at least one of graphite and graphene particles. The curable material is chosen to have good electrical conduction and thermal conduction properties when in a cured state. The curable material typically includes a carrier material, such as a polymer.
Advantageously the curable material can be in the form of a paste when applied to the heat sink and / or the or each solid state lighting device. The curable material can comprise a thick-screen paste conductor, such as a metallic screen paste material, for example at least one of a silver conductor paste, gold conductor paste, copper conductor paste, platinum conductor paste. The curable material can comprise a non-metallic screen conductor paste such as at least one of a graphite conductor paste and a graphene conductor paste.
Typically the curable material is electrically conductive in a non-cured state, and the curing process improves the conductivity of the curable material, as well as fixing its structure.
Advantageously the curable material has as thermal conductivity of at least 7 W/mK when in a cured state, preferably at least 10 W/mIC, and more preferably still at least 15 W/mK.
Preferably the thermal conductivity is of the material is high, typically at least 1 OOWJmK, and preferably is at least 150 W/mK.
Advantageously the or each solid state lighting device includes electrical terminals and the method includes bonding at least one, and preferably a plurality, of the electrical terminals to the heat sink with the curable material.
Advantageously at least one of the solid state lighting devices includes a base, and the method includes bonding the base of at least one, and preferably a plurality, of the solid state lighting devices to the heat sink. The base material is selected to be a good thermal conductor, for example the base can include a thermally conductive ceramic. In preferred embodiments the base comprises a sapphire substrate thermal pad.
Advantageously the first solid state lighting device can include a first electrical terminal, and the method includes bonding the first electrical terminal to the heat sink via a first portion of the curable material.
Advantagcously the method includes forming electrical connectors on the heat sink with the curable material. For example, the lighting unit can include a plurality of solid state lighting devices and the method includes electrically connecting at least two of the solid state lighting devices together with the curable material. The method can include using the curable material to electrically connect at least one of the solid state lighting devices with another electrical component.
Advantageously the first solid state lighting device can include a thermally conductive base. The method can include connecting the thermally conductive base to the heat sink via a second portion of the curable material.
Advantageously the method can include providing a second solid state lighting device and bonding the second solid state lighting device to the heat sink using the curable material.
The second solid state lighting device can include a thermally conductive base, and the method can include connecting the thermally conductive base to the heat sink via a third portion of the curable material.
The second solid state lighting device can include a second electrical terminal and the method can include mounting the second electrical terminal in contact with the first portion of the curable material. The second portion of curable material comprises an electrical connection between the first and second solid state lighting devices.
Advantageously the method can include including providing a third solid state lighting device and bonding the third solid state lighting device to the heat sink using the curable material.
The third solid state lighting device can include a thermally conductive base, and the method can include connecting the thermally conductive base to the heat sink via a fourth portion of the electrically conductive curable material.
The third solid state lighting device can include a third electrical terminal, and the method can include bonding the third electrical terminal in contact with a fifth portion of the curable material.
Advantageously the second solid state lighting device can include an additional electrical terminal which can be connected to the fifth portion of electrical material. The fifth portion of electrically conductive curable material provides an electrical connection between the second and third solid state lighting devices. Thus the first, second and third solid state lighting devices can be connected in series using the second and fifth portions of electrically conductive material.
The first and third solid state lighting devices can each include an additional terminal. The additional terminal of the first solid state lighting device can be bonded to the heat sink using a sixth portion of the curable material. The additional terminal of the third solid state lighting device can be bonded to the heat sink using a seventh portion of the curable material.
The method can include connecting the solid state lighting device(s) to a power source. For example, the method can include bonding power wires to at least one of a solid state lighting device terminal and one of the portions of curable material. Preferably one of the power wires is bonded to the sixth portion of curable material. Preferably one of the power wires is bonded to the seventh portion of curable material.
It will be appreciated by the skilled person that additional or fewer portions of electrically conductive curable material can be used depending on the number of solid state lighting devices used and the circuit layout.
Advantageously in a first embodiment the heat sink can be made entirely from a non-electrically conductive material. For example, the heat sink can be made from at least one of a thennally conductive ceramic and/or a thermally conductive plastics material, which is not electrically conductive at the normal operating voltages and currents for solid state lighting devices.
In a second embodiment the heat sink can include a body having an electrically conductive material, wherein the body includes at least a portion of non-electrically conductive material. Advantageously the body can be at least partly metallic and wherein at least a part of the body is pre-treated with a non-electrically conductive coating. For example, the body can include at least one of aluminium, copper, brass, silver, platinum or any other metal that transfers heat efficiently. The body can be treated by applying a non-electrically conductive coating! layer to at least a portion of the body, and preferably to the whole of the body. Suitable treatments can include at least one of anodising, painting, powder coating, applying a plastics layer, a printed polymer layer or any process that allows thc material properties to be altered to be non-electrically conductive. Ideally the coating will be thin, or will be selected such that it has good thermal conductivity properties. In a preferred embodiment, the heat sink includes an aluminium body that has been anodised.
Advantageously the method can include bonding at least one further solid state lighting device to the heat sink using the curable material.
Advantageously the method can include electrically insulating at least some of the electrically conductive curable material, for example by applying a non-electrically conductive curable material over exposed areas of the electrically conductive material.
This is to protect the electrical connections and reduce the possibility of a user receiving an electrical shock.
The method can include printing, and preferably screen printing, the non-electrically conductive curable material over exposed areas of the electrically conductive material, preferably when in the cured state. The non-electrically conducting curable material can be in the form of a paste in its non-cured state. For example, the curable material can comprise an overglaze, insulating and sealing dielectric, or a protective polymer coating, which are all known in the art.
The method can include curing the non-electrically conducting curable material. This can be done simultaneously with, or separately from, the curing process for the electrically conductive curable material.
Advantageously the method can include heating at least one of the electrically conductive and the non-electrically conductive curable materials to a curing temperature.
Advantageously the curable materials can be thermo-setting materials.
Advantageously the method can include curing at least one of the electrically conductive and the non-electrically conductive curable materials at a predetermined temperature for a predetermined period of time.
The electrically conductive material is preferably selected to cure at room temperature, i.e. typically at a temperature of at least 1OC. Preferably the material cures at a temperature of less than 40C. For some curable materials it is necessary to heat the material to a higher temperature, for example in an oven. Typically an oven is set to a predetermined temperature, which is typically at least 5 DC. The oven temperature is typically less than or equal to 250C. The temperature is selected such that it does not damage the LED. The material is cured for a predetermined period of time, typically in excess of 10 minutes. In some instances more than one curing process may be required. The method can include curing at least one of the electrically conductive curable material and the non-electrically conductive curable materials at a temperature that is greater than or equal to 50C, preferably greater than equal to 75C, more preferably greater than or equal to 1 OOC and more preferably still greater than or equal to I 25C.
Advantageously the method can include mounting the heat sink -solid state lighting device sub-assembly into a lighting housing.
Advantageously the or each solid state lighting device can include at least one optical device, such as at least one lens, reflector and dififiser, for guiding light emitted by a light generating part of the solid state lighting device.
According to another aspect of the invention there is provided a lighting unit according to claim 35.
Advantageously the electrically conductive material can include metal. For example, can include at least one of aluminium, copper, brass, silver, platinum.
Advantageously the electrically conductive material can include a cured metallic paste.
Advantageously the electrically conductive material can include a cured non-metal such as at least one of graphite and graphene.
Advantageously the or each solid state lighting device can include electrical terminals, wherein at least one, and preferably a plurality, of the electrical terminals are bonded to the heat sink with the curable material.
Advantageously at least one of the solid state lighting devices includcs a thermally conductive base, wherein at least one, and preferably a plurality, of the bases are bonded to the heat sink.
Advantageously the first solid state lighting device can include a first electrical terminal, and the first electrical terminal is bonded to the heat sink by a first portion of the electrically conductive material.
Advantageously the first solid state lighting device can include a thermally conductive base.
Advantageously the thermally conductive base is bonded to the heat sink by a second portion of the electrically conductive material.
Advantageously the electrically conductive material has as thermal conductivity of at least 7 W/mK when in a cured state, preferably at least 10 W/mK, and more preferably still at least 15 W/mK. Preferably the thermal conductivity is of the material is high, typically at least 1 OOW/mK, and preferably is at least 150 W!mK.
Advantageously the lighting unit can include a second solid state lighting device bonded to the heat sink by the electrically conductive material. The second solid state lighting device can include a thermally conductive base, wherein the thermally conductive base is bonded to the heat sink by a third portion of the curable material. The second solid state lighting device can include a second electrical terminal bonded to the heat sink by the first portion of the electrically conductive material.
Advantageously the lighting unit can include a third solid state lighting device bonded to the heat sink by the electrically conductive material. The third solid state lighting device can include a thermally conductive base, which is bonded to the heat sink via a fourth portion of the electrically conductive material. The third solid state lighting device can include a third electrical terminal, which is bonded to the heat sink by a fifth portion of the electrically conductive curable material.
Advantageously the second solid state lighting device includes an additional electrical terminal which is bonded to the heat sink by the fifth portion of electrically conductive material. The fifth portion of electrically conductive material provides an electrical connection between the second and third solid state lighting devices. Thus the first, second and third solid state lighting devices are connected in series using the second and fifth portions of electrically conductive material.
The first and third solid state lighting devices each include an additional terminal. The lighting unit can include at least one additional portion of curable electrically conductive material to bond the additional tenninals to thc heat sink. The lighting unit can include wires electrically connected to the solid state lighting devices, and / or to electrically conductive material to allow the solid state lighting devices to be connected to a power source. It will be appreciated by the skilled person that additional or fewer portions of electrically conductive curable material can be provided depending on the number of solid state lighting devices used and the circuit layout.
Advantageously the heat sink can be made entirely from a non-electrically conductive material. For example, the heat sink can be made from at least one of a thermally conductive ceramic and a thermally conductive plastics material, which is not electrically conductive.
Alternatively, the heat sink can comprise a body including an electrically conductive material, wherein the body includes at least a portion of non-electrically conductive material. Advantageously the body can be at least partly metallic and wherein at least part of the body has been pre-treated with a non-electrically conductive coating. For example, the body can include aluminium, copper, brass, silver, platinum or any other metal that transfers heat efficiently. The body can be treated by applying a non-electrically conductive coating / layer to at least a portion of the body, and preferably to the whole of the body. Suitable treatments can include at least one of anodising, painting, powder coating, applying a plastics layer, and a printable dielectric layer. Ideally the coating will be thin, or will be selected such that it has good thermal conductivity properties. In a preferred embodiment, the heat sink includes an aluminium body that has been anodised.
Advantageously the lighting unit can include at least one ffirther solid state lighting device bonded to the heat sink by the electrically conductive material.
Advantageously at least some of the electrically conductive material can be insulated by a non-electrically conductive cured material. This is to protect the electrical connections and reduce the possibility of a user receiving an electrical shock. The non-electrically conducting cured material can be in the form of an overglaze, insulating and sealing dielectric, or a protective polymer coating.
Advantageously the method can include mounting the heat sink -solid state lighting device sub-assembly into a lighting housing.
Advantageously thc or each solid state lighting device can include at least one optical device, such as at least one lens, reflector and diffuser, for guiding light emitted by a light generating part of the solid state lighting device.
Advantageously the lighting unit can be in the form of a downlight arranged to fit within an aperture in a partition. The downlight can include a lighting unit according to any configuration described herein.
According to another aspect of the invention, there is provided a method for manufacturing a lighting unit, the method including: providing at least a first solid state lighting device; providing a heat sink, wherein at least a part of the heat sink is non-electrically conductive; attaching the first solid state lighting device to the non-electrically conductive part of the heat sink using a curable material, the curable material being a thermally conductive material in a cured state; and curing the curable material thereby fixing the first solid state lighting device to the heat sink, the arrangement being such that at least some of the heat generated by the first solid state lighting device, in use, is thermally conducted to the heat sink through the cured material. With this method, similar benefits to those described above can be achieved by using a thermally conductive curing agent, that isn't necessarily electrically conductive, for mechanically and thermally bonding the solid state lighting devices to the heat sink. Electrical connections between the solid state lighting devices can be formed by an electrically conductive curable material in a similar manner to those disclosed herein.
According to another aspect of the invention, there is provided a method for manufacturing a lighting unit, the method including: providing at least a first solid state lighting device; providing a heat sink, wherein at least a part of the heat sink is non-electrically conductive; bonding the first solid state lighting device to the non-electrically conductive part of the heat sink using a thermally conductive material, the arrangement being such that at least some of the heat generated by the first solid state lighting device, in use, is thermally conducted to the heat sink through the thermally conductive bond. Advantageously the solid state lighting device can include an electrically conductive material.
A lighting unit, including: at least a first solid state lighting device; a heat sink, wherein at least a part of the heat sink is non-electrically conductive; wherein the first solid state lighting device is bonded to the non-electrically conductive part of the heat sink by a conductive material, the arrangement being such that at least some of the heat generated by the LED, in use, is thermally conducted to the heat sink via the conductive material.
According to another aspect of the invention, there is provided a lighting unit, including: a heat sink, the heat sink including an anodised aluminium body; and at least one solid state lighting device; whcrein the or each solid state lighting device is bonded to the anodised aluminium body using an electrically conductive cured silver paste.
An embodiment of the present invention will now be described, by way of example only, with reference to the accompanying drawings in which: Figure 1 is a diagrammatic illustration of part of a first prior art LED lighting unit; Figure 2 is a diagrammatic illustration of part of a second prior art LED lighting unit; Figure 3 is a diagrammatic illustration of part of a third prior art LED lighting unit; Figures 4a and 4b are diagrammatic illustrations of part of a fourth prior art LED lighting unit; Figure 5 is a diagrammatic cross-sectional view of part of an LED lighting unit according to an embodiment of the invention; Figure 6 is a plan view of part of an LED lighting unit according to the embodiment of Figure 5; and Figure 7 is a flow chart illustrating the manufacturing process for mounting the LEDs onto a heat sink.
Figures 5 and 6 show part of a lighting unit 1 in accordance with a first embodiment of the invention.
The lighting unit includes first, second and third solid state lighting devices 401a-c, which are typically LED devices, a heat sink 413, and electrical connections 421,427,429,431.
The solid state lighting devices 40 la-c each include two electrical terminals (not shown), and are connected together in series by electrical connections 421,427. The solid state lighting devices 4Ola-c are connectable to a power supply via wires (not shown) that are electrically connected to electrical connections 429,431. Each of the solid state lighting devices 401a-c, includes a sapphire substrate thermal pad 415a-c on the base of the LED for transferring heat, which is generated in use, away from the LED.
The heat sink 413 comprises an extruded aluminium body (a plan view of which can be seen in Figure 6) that has been anodised. The anodising process provides a protective layer 41 3a to the aluminium body that resists corrosion. However, the inventors have realised that the protective layer 413 a is an electrical insulator at the typical voltages and currents that are used for LED lighting units, and therefore can be used to prevent the aluminium body from being electrically connected to the solid state lighting devices 5 and the electrical connections 421,427,429,431.
This realisation enabled the new lighting unit structure to be developed and a new process for manufacturing the structure.
The heat sink-solid state lighting device 413-401a-c subassembly is typically mounted into a lighting housing (not shown). The unit can include at least one optical device such as a lens, reflector or diffuser.
The method of manufacturing the lighting unit will now be described with reference to Figures 5 to 7.
Discrete portions 419,421,423,425,427,429,431 of an electrically conductive curable paste, typically a curable metallic paste such as a polymer silver conductor paste, which are commercially available, are screen printed onto the anodized surface 4l3a of the heat sink.
The polymer silver conductor paste is a resin material that contains silver particles. Typical properties for the electrically conductive paste are: Cured Thickness: (measured on a 100mm x 0.25 mm conductor track) 10 -20 jim Resistivity: (measured on a 100 mm x 0.25 mm conductor track at 1 Ojim cured thickness) < 50 mQ/sq Printing Resolution: (line/space) 50 jim / 50 gm (subject to screen suitability) Volume Resistivity: (calculated from sheet resistance) < x 10-5 ohms I cm Thixotropic Index: (taken at 1 rpm and 10 rpm on Brookfield RVT) 3 -7 The portions 419,423,425 are substantially rectangular in plan. The portions 421,427 are arranged as tracks that are arranged to connect the solid state lighting devices 401a-c together. The portions 429,431 are arranged as tracks and are arranged to connect two of the solid state lighting devices 401 a,401 c to power wires.
Each of the solid state lighting devices 401 a-c is then mounted onto some of the discrete portions of curable metallic paste 419,421,423,425,427,429,431. The thermal pad 41 5a of the first solid state lighting device 401a is placed onto the discrete portion 419, one of its electrical terminals onto the discrete portion 421, and the other of its terminals onto the discrete portion 429. The thermal pad 415b of the second solid state lighting device 4Olb is placed onto the discrete portion 423, one of its electrical terminals onto the discrete portion 421, and the other of its terminals onto the discrete portion 427. The thermal pad 41 5c of the third solid state lighting device 4Olc is placed onto the discrete portion 425, one of its electrical terminals onto the discrete portion 427, and the other of its terminals onto one end of the discrete portion 431.
Power wires are connected to discrete portions 429,431.
Each of the solid state lighting devices 401 a-c is bonded to the anodized surface 41 3a of the heat sink 413 by curing the electrically conductive curable material. The curing process depends on the exact material that is being used, for example some materials cure at room temperature. Other types of material require heating, typically in an oven, to a curing temperature. The material is exposed to the curing temperature for the required period of time. For example, the curing temperature of the polymer silver conductor paste is 125C.
The curing process allows cross linking' of the polymers, which enables the conductive metal particles to move closer together thereby increasing the conductivity of the material when in the cured state. At the end of the curing process, the material sets in a maimer that retains some flexibility.
Thus each of the solid state lighting devices 401a-c is bonded to the anodized surface 413a of the heat sink. The cured material mechanically connects the solid state lighting devices 401 a-c to the heat sink 413, provides thermally conductive pathways directly between the solid state lighting devices 40 la-c and the heat sink, and provides an electrical circuit directly on the heat sink. The anodized surface 4l3a of the heat sink prevents the solid state lighting devices 401 from being electrically connected to the aluminum body of the heat sink.
Optionally, the process can include covering at least some of the exposed parts of the cured electrically conductive material with an electrically insulating material. The preferred way of doing this is to screen print an electrically insulating coating over at least of some the exposed electrically conductive material, and allowing the insulator material to cure. A suitable material for this is a protective polymer, for example protective polymer coating which is commercially available. The polymer coating is preferably a thermo-setting coating.
A significant proportion of the heat generated by the solid state lighting devices 4Ola-c, in use, is transferred by conduction to the heat sink 413 through the cured material 419,421,423,425,427,429,431. It can be scen from Figure 5, that this reduces the number of thermal boundaries that the heat has to cross when moving from the solid state lighting devices 401a-c to the heat sink 413, when compared to the prior art devices. Thus the process of bonding the solid state lighting devices 4Ola-c directly to the heat sink obviates the need for solder, a separate PCB and thc application of a dielectric layer onto the hcat sink. The improved process reduces the manufacturing time, cost, labour, materials and the number of manufacturing processes required to produce the lighting unit.
The lighting unit produced by the manufacturing method has improved thermal management, which provides a lower junction temperature (Ti) at the LED, due to reduced thennal resistance of the system, as there are less thermal boundaries for heat to travel through.
It will be apparent to the skilled person that modifications can be made to the above embodiment that falls within the scope of the invention, for example the number of solid state lighting device can be any practicable number. The lighting unit includes at least one solid state lighting device, preferably a plurality of solid state lighting devices and typically n solid state lighting devices, where n is in the range 1 to 50. In some large scale devices, n can be greater than 50, for example n may be greater than 100 devices.
The curable materials can be screen printed onto thc solid state lighting devices in addition to, or as an alternative to, the curable material printed onto the heat sink.
Different electrical circuit layouts can be used, according to tile application requirements.
Other thermally conductive materials can be used for the heat sink, such as copper or a thermally conductive ceramic material. Other surface treatments can be applied to the heat sink that are non-electrically conductive, for example the heat sink can be painted, powder coated, or plastic coated or make use of any other suitable pre-treatment. If the heat sink material is non-electrically conducting, such as a thermally conductive ceramic material, it is not necessary to coat the heat sink body with an electrically insulating coating.
Other eleetricaily conductive curable materials can be used, for example a curable material including at least one of copper, gold, platinum, graphite and graphene. The curable material that is used to provide electrical contacts between the solid state lighting devices should be selected to be electrically conductive, at least when in a curcd state.
The curable material that is used to mechanically and thermally bond the thermal pads of the solid state lighting devices to the heat sink is typically an electrically conducting material since metallic curable materials tend to have good thermally conducting properties. This provides the advantage that those portions of curable material can be applied in the same printing process as those portions used for electrical connections, which provides an efficient manufacturing process. However, a non-electrically conductive curable material can be used to bond the thermal pad to the heat sink, provided that it has good thermally conductive properties and sufficient mechanical bond, since an electrical connection is not required between the thermal pad and the heat sink.
Although all of the portions of electrically conductive material are shown as separated discrete portions, it will be appreciated that some portions can be joined together so that they are contiguous provided that this does not adversely affect the operation of the electrical circuit.

Claims (57)

  1. Claims 1. A method for manufacturing a lighting unit, the method including: providing at least a first solid state lighting device; providing a heat sink, wherein at least a part of the heat sink is non-electrically conductive; attaching the first solid state lighting device to the non-electrically conductive part of the heat sink using a curable material, the curable material being an electrically conductive material in a cured state; and curing the curable material thereby fixing the first solid state lighting device to the heat sink, the arrangement being such that at least some of the heat generated by the first solid state lighting device, in use, is thermally conducted to the heat sink through the cured material.
  2. 2. A method according to claim 1, wherein the curable material is applied to at least one of the heat sink and the or each solid state lighting device by a printing process.
  3. 3. A method according to claim 2, wherein the curable material is applied to the heat sink and / or the or each solid state lighting device by a screen printing process.
  4. 4. A method according to any one of the preceding claims, wherein the curable material includes at least one of a metal, such as at least one of silver, copper, platinum and gold; and a non-metal, such as at least one of graphite and graphene.
  5. 5. A method according to any one of the preceding claims, wherein the curable material is in the form of a paste when applied to the heat sink and I or the or each solid state lighting device.
  6. 6. A method according to any one of the preceding claims, wherein the or each solid state lighting device includes electrical terminals, and including bonding at least one of the electrical terminals to the heat sink with the curable material.
  7. 7. A method according to any one of the preceding claims, wherein at least one of the solid state lighting devices includes a base, and the method includes bonding the base of at least onc of the solid state lighting devices to the hcat sink.
  8. 8. A method according to any one of the preceding claims, including forming electrical connectors on the heat sink with the curable material.
  9. 9. A method according to claim 8, wherein the lighting unit includes a plurality of solid state lighting devices and the method includes forming with the curable material at least part of an electrical connection linking at least two of the solid state lighting devices together.
  10. 10. A method according to any one of the preceding claims, wherein the first solid state lighting device includes a first electrical terminal, and including fixing the first electrical terminal to the heat sink via a first portion of the curable material.
  11. 11. A method according to any one of the preceding claims, wherein the first solid state lighting device includes a thermally conductive base.
  12. 12. A method according to claim 11, including connecting the thermally conductive base to the heat sink via a second portion of the curable material.
  13. 13. A method according to any one of the preceding claims, wherein the curable material has as thermal conductivity of at least 7W/mK when in a cured state, and preferably at least 1 OW/mK, and more preferably still at least I 5W/mK.
  14. 14. A method according to any one of the preceding claims, including providing a second solid state lighting device and fixing the second solid state lighting device to the heat sink using the curable material.
  15. 15. A method according to claim 14, wherein the second solid state lighting device includes a thermally conductive base, and including connecting the thermally conductive base to the heat sink via a third portion of the curable material.
  16. 16. A method according to claim 14 when dependent on claim 10, or claim 15 when dependent on claim 10, wherein the second solid state lighting device includes a second electrical terminal and fixing the second electrical terminal to the heat sink using the first portion of the curable material.
  17. 17. A method according to any one of the preceding claims, including providing a third solid state lighting device and fixing the third solid state lighting device to the heat sink using curable material.
  18. 18. A method according to claim 17, whercin the third solid state lighting device includes a thermally conductive base, and including connecting the thermally conductive base to the heat sink via a fourth portion of the electrically conductive curable material.
  19. 19. A method according to claim 17 or 18, wherein the third solid state lighting device includes a third electrical terminal, and fixing the third electrical terminal to the heat sink using the fifth portion of the curable material.
  20. 20. A method according to any one of the preceding claims, wherein the heat sink is made entirely from a non-electrically conductive material.
  21. 21. A method according to any one of claims 1 to 19, wherein the heat sink includes a body including an electrically conductive material, wherein the body includes at least a portion of non-electrically conductive material.
  22. 22. A method according to any one of claims I to 19 and 21, wherein the body is at least partly metallic and wherein at least part of the body is pre-treated with a non-electrically conductive coating.
  23. 23. A method according to any one of the preceding claims, including fixing at least one tbrther solid state lighting device to the heat sink using the curable material.
  24. 24. A method according to any one of the preceding claims, including applying a non-electrically conductive curable material over exposed areas of the electrically conductive cured material.
  25. 25. A method according to claim 24, including printing, and preferably screen printing, the non-electrically conductive curable material over exposed areas of the electrically conductive cured material.
  26. 26. A method according to claim 24 or 25, wherein the non-electrically conducting curable material is in the form of a paste in it non-cured state.
  27. 27. A method according to any one of claims 24 to 26, including curing the non-electrically conducting curable material.
  28. 28. A method according to any one of the preceding claims, including heating at least one of the electrically conductive curable material and the non-electrically conductive curable material to a curing temperature.
  29. 29. A method according to any one of the preceding claims, including curing at least one of the electrically conductive curable material and the non-electrically conductive curable material at a predetermined temperature for a predetermined period of time.
  30. 30. A method according to any one of the preceding claims, wherein the or each solid state lighting device includes a primary lens for guiding light emitted by a light generating part of the solid state lighting device.
  31. 31. A method according to any one of the preceding claims, including mounting the heat sink -solid state lighting device sub-assembly into a lighting housing.
  32. 32. A method according to any one of the preceding claims, including mounting a secondary lens onto the heat sink -solid state lighting device sub-assembly.
  33. 33. A method according to any one of the preceding claims, wherein the or each solid state lighting device includes an LED.
  34. 34. A method according to any one of the preceding claims, wherein the curable material is electrically conductive in a non-cured state.
  35. 35. A lighting unit, including: at least a first solid state lighting device; a heat sink, wherein at least a part of the hcat sink is non-elcctrically conductive; wherein the first solid state lighting device is bonded to the non-electrically conductive part of the heat sink by an electrically conductive material, the arrangement being such that at least some of the heat generated by the LED, in use, is thermally conducted to the heat sink via the electrically conductive material.
  36. 36. A lighting unit according to claim 35, wherein the electrically conductive material includes at least one of a metal, such as at least one of a metal, such as at least one of silver, copper, platinum and gold; and a non-metal, such as at least one of graphite and graphene.
  37. 37. A lighting unit according to claim 35 or 36, wherein the electrically conductive material includes a cured metallic paste.
  38. 38. A lighting unit according to any one of claims 35 to 37, wherein the first solid state lighting device includes a first electrical terminal, and the first electrical terminal is bonded to the heat sink by a first portion of the electrically conductive material.
  39. 39. A lighting unit according to any one of claims 35 to 38, wherein the first solid state lighting device includes a thermally conductive base.
  40. 40. A lighting unit according to claim 39, wherein the thermally conductive base is bonded to the heat sink by a second portion of the electrically conductive material.
  41. 41. A lighting unit according to any one of claims 35 to 40, wherein the electrically conductive material has as thermal conductivity of at least 7W/mK when in a cured state, and preferably at least IOW!mK, and more preferably still at least 15W/mK..
  42. 42. A lighting unit according to any one of claims 35 to 41, including a second solid state lighting device bonded to the heat sink by the electrically conductive material.
  43. 43. A lighting unit according to claim 42, wherein the second solid state lighting device includes a thermally conductive base, wherein the thermally conductive base is bonded to the heat sink by a third portion of the curable material.
  44. 44. A lighting unit according to claim 42 when dependent on claim 38, or claim 43 when dependent on claim 38, wherein the second solid state lighting device includes a second electrical tcrminal bonded to the heat sink by the first portion of the electrically conductive material.
  45. 45, A lighting unit according to any one of claims 35 to 44, including a third solid state lighting device bonded to the heat sink by the electrically conductive material.
  46. 46. A lighting unit according to claim 42, wherein the third solid state lighting device includes a thermally conductive base, which is bonded to the heat sink via a fourth portion of the electrically conductive material.
  47. 47. A lighting unit according to claim 45 or 46, wherein the third solid state lighting device includes a third electrical terminal, which is bonded to the heat sink by a fifth portion of the curable material.
  48. 48. A lighting unit according to any one of claims 35 to 47, wherein the heat sink is made entirely from a non-electrically conductive material.
  49. 49. A lighting unit according to any one of claims 35 to 47, wherein the heat sink includes a body including an electrically conductive material, wherein the body includes at least a portion of non-electrically conductive material.
  50. 50. A lighting unit according to any one of claims 35 to 47 and 49, wherein the body is at least partly metallic and wherein at least part of the body has been pre-treated with a non-electrically conductive coating.
  51. 51. A lighting unit according to any one of claims 35 to 50, including at least one further solid state lighting device bonded to the heat sink by the electrically conductive material.
  52. 52. A lighting unit according to any one of claims 35 to 51, wherein at least some of the electrically conductive material is insulated by a non-electrically conductive cured material.
  53. 53. A lighting unit according to claim 52, wherein the non-electrically conducting cured material is in the form of an overglaze, insulating and sealing dielectric, or a protective polymer coating.
  54. 54. A lighting unit according to any one of claims 35 to 53, wherein the or each solid state lighting device includes a primary lens for guiding light emitted by a light generating part of the solid state lighting device.
  55. 55. A lighting unit according to any one of claims 35 to 54, including a housing for housing the heat sink solid state lighting device sub-assembly.
  56. 56. A lighting unit according to any one of claims 35 to 55, including a secondary lens device.
  57. 57. A downlight arranged to fit within an aperture in a partition, including a lighting unit according to any one of claims 35 to 56.
GB1302692.7A 2013-02-15 2013-02-15 Method for manufacturing a lighting unit and lighting unit Active GB2510865B (en)

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Cited By (1)

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Publication number Priority date Publication date Assignee Title
FR3107752A1 (en) * 2020-02-28 2021-09-03 Valeo Iluminacion Automotive lighting device

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US20030193055A1 (en) * 2002-04-10 2003-10-16 Martter Robert H. Lighting device and method
GB2422249A (en) * 2005-01-15 2006-07-19 Robert John Morse Power substrate
US20060202850A1 (en) * 2005-02-14 2006-09-14 Craig Hefright LED strip light lamp assembly
US20100240158A1 (en) * 2005-09-22 2010-09-23 The Artak Ter-Hovhanissian Patent Trust Led lighting with integrated heat sink and process for manufacturing same
US20100308707A1 (en) * 2009-06-09 2010-12-09 Fu Zhun Precision Industry (Shen Zhen) Co., Ltd. Led module and method of fabrication thereof
US20120025257A1 (en) * 2010-07-29 2012-02-02 Getac Technology Corporation Led assembly and manufacturing method thereof
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US5857767A (en) * 1996-09-23 1999-01-12 Relume Corporation Thermal management system for L.E.D. arrays
US20030193055A1 (en) * 2002-04-10 2003-10-16 Martter Robert H. Lighting device and method
GB2422249A (en) * 2005-01-15 2006-07-19 Robert John Morse Power substrate
US20060202850A1 (en) * 2005-02-14 2006-09-14 Craig Hefright LED strip light lamp assembly
US20100240158A1 (en) * 2005-09-22 2010-09-23 The Artak Ter-Hovhanissian Patent Trust Led lighting with integrated heat sink and process for manufacturing same
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FR3107752A1 (en) * 2020-02-28 2021-09-03 Valeo Iluminacion Automotive lighting device

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