EP3194837A1

EP3194837A1 - Substrate for a light module with metal strip used as shielding, a heat screen and/or an optical reflector

Info

Publication number: EP3194837A1
Application number: EP15760165.9A
Authority: EP
Inventors: Hui Jin; Zdravko Zojceski; Christophe Dubosc
Original assignee: Valeo Vision SAS
Current assignee: Valeo Vision SAS
Priority date: 2014-09-15
Filing date: 2015-09-07
Publication date: 2017-07-26
Also published as: US20170254499A1; FR3025859A1; WO2016041801A1; CN106716005A

Abstract

The invention relates to a light module (2), especially for a motor vehicle, comprising a substrate (4), at least one light source (8, 9) arranged on the substrate (4), and a metal coating on the substrate, forming strips (14, 16, 22, 24, 26) for the electrical power supply of the light sources (8, 9). The metal coating extends at a distance from the power supply strips (14, 16, 22, 24, 26) and/or transversely to said strips, in such a way as to form at least one auxiliary area (18, 20) ensuring the function of a heat screen, a reflective surface, an aesthetic surface, and/or electromagnetic shielding.

Description

LUMINOUS MODULE SUBSTRATE WITH METALLIC TRACK FOR SHIELDING, THERMAL SCREEN AND / OR OPTICAL REFLECTOR

The invention relates to the field of lighting and / or light signaling, in particular for a motor vehicle. More specifically, the invention relates to the field of lighting and light signaling by means of electroluminescence diodes (LED), and more particularly of organic electroluminescence diodes (OLED).

The published patent document FR 2 995 657 A1 discloses an OLED type diode light source, comprising a support with cavities filled by the diodes. The support comprises on one of its faces electrodes or electrical tracks for electrically contacting the diodes for their power supply. The diodes comprise a stack of organic layers and a transparent substrate disposed on the stack in question. The substrate has a larger surface area than the organic layers to extend beyond the corresponding cavity and thus come to contact the electrical tracks, near the cavity. The support is made by injection of insulating material such as thermoplastic or thermosetting plastic. It can be plane, with a jump or even more complex shape. The electrical tracks are limited to ensure the power of the diodes. The function provided by the light source of this teaching is limited to its own function. An optical system is indeed necessary to produce a light module.

The patent document US 2005/0243558 A1 discloses an LED support for a signal module of the type of taillights of a motor vehicle. It consists of a printed circuit board and comprises a series of orifices through which are inserted LEDs of the type of inverted mounting. These LEDs comprise optical parts in the form of domes, these domes being visible on the side of the front face. The LEDs include fastening and electrical connection tabs soldered with electrical tracks on the back side of the board. This arrangement provides an aesthetic support when viewed from a point of view located on the front side, the electrical connections being exclusively on the back side. In addition, it allows the installation of a radiator on the back side of the base of the LED. Similar to the two previous teachings, the support of LED disclosed in this teaching is interesting for flat mounts. However, it is less so for complex shaped signal modules. In addition, similar to the previous teaching, the function provided by the light source is limited to its own function in that an optical system is necessary to achieve a light module.

The object of the invention is to propose a light module of optimized construction, particularly from the point of view of the integration of the light source or sources.

The subject of the invention is a lighting and / or light-signaling module, in particular for a motor vehicle, comprising: a substrate; one or more light sources disposed on the substrate; a set of metal tracks disposed on the substrate, the assembly forming at least one electrical supply zone of the light source or sources; remarkable in that a part of the set of metal tracks extends at a distance from the or at least one of the feed zones and / or transversely to said at least one of said zones, so as to form one or more auxiliary zones distinct from a power supply function, for example a heat shield, reflection surface, aesthetic surface, and / or electrical or magnetic shielding.

In other words, the auxiliary zone or zones are devoid of any influence as to the power supply of the light source or sources. The concept of auxiliary zone providing a heat shield function is understood to mean an auxiliary zone allowing conduction and dissipation of heat.

According to an advantageous embodiment of the invention, the at least one auxiliary zone is non-coplanar with the region or regions of the substrate supporting the light source or sources. According to an advantageous embodiment of the invention, the or at least one of the auxiliary zones is connected to a supply track of the or at least one of the light sources, said track being intended to be connected to the ground, said or said auxiliary zones providing an electrical shielding function.

The auxiliary zones may comprise copper, with a copper thickness of at least 2 μιτι, or even 5 to 15 μιτι. Advantageously, the set of tracks forms several auxiliary zones, these auxiliary zones extending relative to each other in a non-coplanar manner. The auxiliary zones thus form a Faraday cage to complete the electrical shielding function. According to an advantageous embodiment of the invention, the metal coating of the at least one auxiliary zone comprises nickel, the at least one auxiliary zone providing a magnetic shielding function. In this case, it is possible to provide a nickel thickness of at least 2 μιτι, or even 5 to 10 μιτι.

According to an advantageous embodiment of the invention, the or at least one of the light sources is of the organic light-emitting diode type projecting from the substrate.

According to an advantageous embodiment of the invention, the substrate comprises a cavity with a bottom and at least one side wall, the or at least one of the auxiliary zones extending on the side wall or walls, providing a heat shield function, reflecting surface and / or aesthetic surface. The or at least one of the light sources may be disposed on the bottom of the cavity. The tracks of the auxiliary zone may comprise a layer of copper arranged for the auxiliary zone to provide a heat shield function. For example, the copper layer may have a thickness of 15-30 μιτι micrometers. According to an advantageous embodiment of the invention, the metal coating of the auxiliary zone (s) of heat shield, reflection surface and / or aesthetic surface comprises copper, silver and / or gold. The tracks of the auxiliary zone may comprise a layer of gold or silver arranged for the auxiliary zone to provide a reflection surface function. For example, the gold layer may have a thickness of 50 nm so as to ensure a reflectivity of at least 50%.

According to an advantageous embodiment of the invention, the cavity is generally elongated along a main direction, with several of the light sources being disposed on the bottom of the cavity in the main direction. According to an advantageous embodiment of the invention, the light sources are electrically connected in series by the power supply tracks extending according to the main direction of the cavity, the auxiliary zones extending from said tracks, laterally on either side of the main direction.

According to an advantageous embodiment of the invention, the cavity houses an optical device; said device, the light sources housed at the bottom of the cavity and the auxiliary zones extending on the lateral wall or walls forming a signaling light beam.

According to an advantageous embodiment of the invention, the substrate comprises at least one end wall projecting from the one or one of the side walls of the cavity, the or at least one of the shielding auxiliary zones being disposed on the one or one of the walls. front.

According to an advantageous embodiment of the invention, the or each of the auxiliary zones has an average width of more than 3 mm, preferably more than 5 mm.

According to an advantageous embodiment of the invention, the metal coating comprises nickel, gold, silver and / or copper. According to an advantageous embodiment of the invention, the substrate is a rigid molded piece having a three-dimensional shape. Advantageously, the substrate consists essentially of a wall with an average thickness of between 0.5 and 3 mm.

According to an advantageous embodiment of the invention, the substrate is made of a thermoplastic material doped with metal particles so as to allow the clinging of the metal coating.

According to an advantageous embodiment of the invention, the or at least one of the light sources is connected to the electrical supply tracks by an adhesive loaded with metal particles, said adhesive being preferably a polymer adhesive capable of polymerizing after application.

According to an advantageous embodiment of the invention, the module is capable of forming at least one light beam along an optical axis towards the front of the module, the auxiliary zones of the metal coating being disposed on a face of the substrate which is directed towards the before said module. The invention also relates to a light device, especially for a motor vehicle, comprising: a housing; at least one light module capable of forming at least one light beam; remarkable in that the or at least one of the light modules is in accordance with the invention. The measures of the invention are interesting in that they make it possible to achieve with the metallic coating electrical tracks other functions such as electromagnetic shielding functions, heat shield, reflection surface and / or aesthetic. This is all the more interesting when the substrate is molded according to the MID technology (acronym for "Molded Interconnect Device") because the substrate can then become a visible part ensuring, in addition to a supporting function of the light sources, support functions on which optical elements of the module are mounted. The level of integration of functions in the substrate is then particularly high. These measurements are also of economic interest insofar as the deposition operations of the metallic coating of the electric tracks and the auxiliary zones are carried out simultaneously.

Other features and advantages of the present invention will be better understood from the description and the drawings, among which:

- Figure 1 is a perspective view of a light module according to the invention; FIG. 2 is a front view of the module of FIG. 1, but without the central collimator;

FIG. 3 is a perspective and side view of the module of FIGS. 1 and 2.

FIG. 1 illustrates a light-signaling module for a motor vehicle. The module 2 is configured to be housed in a housing disposed at the rear of the vehicle. It is configured to provide a lantern (or taillight) function, a stop lamp function and a direction indicator (or flashing) function.

The module 2 comprises a substrate 4 provided with a central portion 4 ¹ , two side walls ² , two end walls 4 ³ protruding from the side walls 4 ² , two supports 4 ⁴ and a rear portion 4 ⁵ . The rear part 4 ⁵ is configured to cooperate with a power supply connector 6. The two side walls 4 ² form a cavity housing light sources (not visible in Figure 1) and a collimator 10 to form a light beam for a direction indicator function. The supports 4 ⁴ are arranged to protrude from the central portion 4 ¹ of the substrate 4 substantially opposite to each other. Each of these supports 4 ⁴ supports a diode OLED 8. An OLED is a diode electroluminescence comprising a superposition of several organic semiconductor layers between two electrodes one of which (at least) is transparent. In this case, these OLED diodes provide a lantern function. The substrate 4 of the module also supports one or more light sources (not visible) between the side walls 4 ² and the OLED diodes 8, this or these light sources being covered with a collimator 12 to provide a stop lamp function . More precisely, the rays emitted by these light sources are deflected by the collimator 12 to meet the front face of the corresponding OLED diode 8 and be reflected towards the front of the module.

The longitudinal axis of the module shown in FIG. 1 corresponds to its optical axis. This means that the different light beams produced by the module 2 are oriented substantially along this axis. All these beams are preferably directed towards the front of the module (corresponding to the right in Figure 1 and the rear of the vehicle).

The collimators 10 and 12 are parts made of transparent or translucent material, such as glass or polycarbonate (PC) or plexiglass (PMMA). They include input and / or output surfaces oriented to deflect the spokes along a main direction, applying the Snell-Descartes refractive principle. The input and output faces each form a diopter, namely a surface separating two transparent homogeneous and isotropic media of different refractive indices. The refractive index of the air is in fact of the order of 1 while that of the glass and polycarbonate is between about 1, 4 and 1 .6. The operating principle of a collimator is well known to those skilled in the art; it is therefore not necessary to detail it further. The substrate 4 is made of plastic material produced by molding and supports light sources and electric tracks, in accordance with the MID (acronym for "Molded Interconnect Device") technology.

FIG. 2 illustrates the front face of the module 2 of FIG. 1, the central collimator 10 however being absent. FIG. 3 is a side view of the module devoid of the central collimator 10 and the lateral collimators 12.

It can be seen that the two lateral walls 4 ² of the substrate form a cavity housing several light sources of the LED type 9. The latter are distributed along the transverse direction corresponding to the main direction of the cavity. These diodes are fixed directly on the substrate 4, preferably by bonding with an adhesive loaded with metal particles, said adhesive preferably being a polymer adhesive capable of polymerizing after application. The use of glue is advantageous in that it makes it possible to avoid subjecting the substrate to thermal stresses. The diodes 9 are interconnected electrically in series and powered by the electrical tracks 14 and 16. In this case, the track 14 is intended to be brought to a positive potential, such as for example +12 Volt, while the track 16 is intended to be connected to the mass of the vehicle.

It is interesting to note that the front walls 4 ³ comprise electrical tracks 18 connected directly to the ground track 16. These electrical tracks provide a shielding function to external electromagnetic fields. More particularly, they form with the OLED diodes, which comprise electrodes intended to be connected to a positive potential (+12 volts), an electric field. This field being closed is able to protect the operation of the OLED diode from electromagnetic disturbances coming from outside or inherent to the operation of the OLED itself. OLED diodes, because of their larger size, are indeed more sensitive to this type of disturbance and generate certain electrical disturbances that can be harmful to it. The front walls 4 ³ of the substrate 4 extending transversely along the OLED diodes are particularly well positioned to form a closed electromagnetic field with the OLED diodes and the electrical tracks 18. The electrical tracks 18 form thus auxiliary zones providing an electromagnetic shielding function. They also provide an aesthetic function.

It is also interesting to note that the electrical track 14 of positive potential (+12 Volts) extends transversely to its main direction (which is in this case transverse) to areas 20 covering the inner faces of the side walls 4 ² forming the cavity. The same goes for the tracks 22, 24 and 26 interconnecting the diodes 9 in series. These auxiliary zones 20 are at a positive potential when the diodes 9 are powered. They provide a thermal and / or optical shield function in that they protect the walls 4 ² of the substrate 4 supporting them from the potentially important thermal radiation emitted by the diodes 9. Depending on the material used, these zones may also reflect a part of the incident light radiation to the walls supporting them.

The plastic material of the substrate may be doped with metal particles able to ensure the attachment of the metal tracks 14, 16, 18, 20, 22, 24 and 26 on its outer surface.

The electric tracks can be realized by the technology designated by the acronym LDS meaning in English "Laser Direct Structuring". This involves running a laser beam on the corresponding surface of the substrate, according to the configuration of the tracks to be made. The laser beam has the effect of forming a roughness capable of promoting attachment. This step is followed by a metallization by dipping the substrate in one or more successive metal baths.

Alternatively or in a complementary manner, the electrical tracks can be made by ink jet printing, the ink of which comprises metal particles. This printing can be made directly on the substrate, or vairante, on a thin sheet of polyethylene naphthalate (PEN) or polyethylene terephthalate (PET) which will subsequently be deposited on the substrate by vacuum thermoforming.

The tracks can also be made by a two-stage molding of the substrate, or else designated "Two shot molding" in English. This is an injection molding process using two different resins where only one of the two resins is metallizable. Typically, the metallizable resin is ABS and non-metallizable resin is polycarbonate. The substrate is then subjected to an auto-catalytic deposition process where butadiene is used to chemically roughen the surface and allow adhesion of a primary layer of copper. Due to the thermoplastic nature of the substrate, the use of conventional soldering processes for electrical contacts is not suitable. The diodes are thus mechanically and electrically fixed by applying a polymer-based adhesive and loaded with metal elements. It is thus a so-called "cold" application method, that is to say at a temperature, for example 125 ° or 150 °, not harming the substrate. After polymerization of the adhesive, it ensures the mechanical and electrical fixation of the LED.

The electrical tracks 14, 16, 18, 20, 22, 24 and 26 may comprise several layers, in particular copper (Cu), nickel (Ni) and / or gold (Au). The presence of a copper layer is of interest for providing a heat shield function and / or enhancing the electrical shielding function. The presence of a layer of nickel is interesting for providing a magnetic shielding function. The presence of a layer of gold is interesting to ensure an aesthetic or optical function. For example, the electrical tracks may comprise a first copper layer having a thickness of between 10 and 20 μιτι, followed by a layer of nickel having a thickness of about 4 μιτι, and followed by a gold layer with a thickness of less than 1 μιτι.

Auxiliary zones 18 and 20 have an average width of more than 3 mm, preferably more than 5 mm.

Claims

claims

1. Luminous module (2), in particular for a motor vehicle, comprising:

a substrate (4);

one or more light sources (8, 9) arranged on the substrate (4);

a set of metal tracks disposed on the substrate, said assembly forming at least one electrical supply zone (14, 16, 22, 24, 26) of the light source or sources (8, 9);

characterized in that

a part of the set of tracks extends at a distance from the or at least one of the feed zones (14, 16, 22, 24, 26) and / or transversely to said one or at least one of said zones, so as to form one or more auxiliary zones (18, 20) providing an auxiliary function distinct from a power supply function, for example a heat shield, reflection surface, aesthetic surface, and / or electrical shielding or magnetic.

2. Module (2) according to claim 1, characterized in that the or at least one of the auxiliary zones (18) is connected to a feed track (16) of the or at least one of the light sources (9). ), said track (16) being intended to be connected to ground, said auxiliary zone or zones (18) providing an electrical shielding function.

3. Module (2) according to one of claims 1 to 2, characterized in that the metal coating of the or auxiliary zones (18) comprises nickel, said auxiliary zone or zones (18) providing a magnetic shielding function .

4. Module (2) according to one of claims 1 to 3, characterized in that the or at least one of the light sources (8) is of the organic light emitting diode type protruding from the substrate.

5. Module (2) according to one of claims 1 to 4, characterized in that the substrate (4) comprises a cavity with a bottom and at least one side wall (4 ² ), the or at least one of the auxiliary zones (20) extending over the one or more side walls (4 ² ), providing a heat shield, reflection surface and / or aesthetic surface function.

6. Module (2) according to claim 5, characterized in that the metal coating of the or auxiliary zones (20) heat shield, reflection surface and / or aesthetic surface comprises copper, gold and / or money.

7. Module (2) according to one of claims 5 and 6, characterized in that the cavity is generally elongate in a main direction, several of the light sources (9) being disposed on the bottom of the cavity in the main direction.

8. Module (2) according to claim 7, characterized in that the light sources (9) on the bottom of the cavity are electrically connected in series by the power supply tracks (14, 22, 24, 26) s' extending in the main direction of the cavity, the auxiliary zones (20) extending from said tracks (14, 22, 24, 26) laterally on either side of the main direction.

9. Module (2) according to claim 2 and one of claims 5 to 8, characterized in that the substrate (4) comprises at least one end wall (4 ³ ) protruding from the or one of the side walls (4 ² ) of the cavity, the or at least one of the shielding auxiliary areas (18) being disposed on one or one of the front walls (4 ³ ).

10. Module (2) according to one of claims 1 to 9, characterized in that the metal coating comprises nickel, gold, silver and / or copper.

1 1. Module (2) according to one of claims 1 to 10, characterized in that the substrate (4) is a rigid molded part having a three-dimensional shape.

12. Module (2) according to one of claims 1 to 1 1, characterized in that the substrate (4) is in a thermoplastic material doped with metal particles so as to allow the clinging of the metal coating.

13. Module (2) according to one of claims 1 to 12, characterized in that the or at least one of the light sources (8, 9) is connected to the power supply tracks (14, 16, 22, 24, 26) by an adhesive loaded with metal particles, said adhesive being preferably a polymer adhesive capable of polymerizing after application.

14. Module (2) according to one of claims 1 to 13, characterized in that it is capable of forming at least one light beam along an optical axis towards the front of the module, the auxiliary zones (18, 20) metal coating being disposed on a face of the substrate which is directed towards the front of said module.

Luminous device, in particular for a motor vehicle, comprising:

- a housing ;

at least one light module capable of forming at least one light beam;

characterized in that

the or at least one of the light modules is in accordance with one of claims 1 to 14.