Method for manufacturing a three-dimensional article having a metal pattern

Abstract

The present invention relates to a method for manufacturing a three-dimensional article comprising at least one metal pattern, comprising at least a step A of providing a flat substrate made of a thermoforming material, a step B of forming on the surface of the flat substrate a temporary masking coating adhering to said surface in order to obtain a masked substrate having at least one unmasked area, a step C of thermoforming the flat substrate to give it a three-dimensional general shape, a step D of metallizing the masked substrate to form a metal deposit on at least said unmasked area on the masked substrate, and a step E of removing said temporary masking coating, wherein the thermoforming step C is carried out before the metallization step D and before the step E of removing the temporary masking coating, and wherein the metallization step D is carried out by electroless deposition from one or more metallization solutions comprising at least one metal in the form of a metal cation and at least one reducing agent capable of converting the metal cation into a metal, by spraying one or more metallization solutions in the form of one or more aerosols. The present invention also relates to a method for manufacturing a three-dimensional article with a metal pattern.

Description

[Technical field]

[0001] The present invention relates to the general technical field of three-dimensional articles having decorative and / or functional metallic pattern(s).

[0002] More particularly, the present invention relates to a method for producing a three-dimensional article comprising at least one metal pattern. [Background technology]

[0003] In the field of manufacturing objects decorated with metal patterns, methods are known that consist in producing or applying metal patterns to the surface of semi-finished three-dimensional objects, such as glass or plastic vials or bottles, by additive techniques (e.g. screen or pad printing using metallized inks, or application of a metal film by hot stamping) or subtractive techniques (e.g. object surface metallization followed by selective laser engraving). These techniques are capable of producing particularly aesthetic decorative effects, but are nevertheless expensive and difficult to use for large-scale designs. Moreover, they are very difficult, if not impossible, to use to decorate semi-finished three-dimensional objects of complex geometric shapes / topographies, so that they are generally only implemented on substantially flat or cylindrical surface parts of pre-manufactured semi-finished three-dimensional objects.

[0004] In the field of printed electronics, methods are known for manufacturing three-dimensional articles or objects locally covered with conductive metallization, where a conductive pattern is produced on a thermoplastic polymer substrate by direct printing (screen or inkjet printing) using a conductive ink, in particular an ink containing silver particles. Heat and / or chemical treatments are then applied to drive off the solvent contained in the ink and / or to crosslink the polymer matrix of the ink. The substrate is then thermoformed to obtain the desired three-dimensional aspect. In addition to the fact that implementing conductive inks is rather expensive, the electrical performance of the conductive patterns obtained using such inks can still be improved, in particular with regard to the level and uniformity of the conductivity, which in some cases may prove problematic for the correct operation of electronic devices integrating such three-dimensional objects. Summary of the Invention [Problem to be solved by the invention]

[0005] The object assigned to the present invention is therefore to provide a response to the above-mentioned needs and problems, and in particular to propose a new method for the easy and efficient manufacture of three-dimensional objects having decorative and / or functional metallic pattern(s) of a wide variety of shapes and geometries.

[0006] Another object of the invention is to propose a new method making it possible to manufacture three-dimensional articles with metallic pattern(s) of any size.

[0007] Another object of the invention is to propose a new method making it possible to rapidly and relatively cheaply manufacture three-dimensional articles carrying metal pattern(s).

[0008] Another object of the invention is to propose a new method for manufacturing three-dimensional objects with metal pattern(s) that are easy to implement.

[0009] Another object of the invention is to propose a new method for manufacturing three-dimensional objects with metallic pattern(s) that can be industrially implemented.

[0010] Another object of the invention is to propose a new method for manufacturing three-dimensional articles in which the metal pattern(s) can be fine, precise and intricate.

[0011] Another object of the invention is to propose a new method for manufacturing three-dimensional articles in which the metal pattern(s) are particularly resistant to external attack.

[0012] Another object of the invention is to propose a new method for manufacturing three-dimensional articles in which the metal pattern(s) are particularly uniform and regular, both in terms of thickness and surface appearance.

[0013] Another object of the invention is to propose a new method for manufacturing three-dimensional articles with metal pattern(s), which allows excellent control over the shape of the metal pattern(s). [Means for solving the problem]

[0014] The object assigned to the present invention is a method for manufacturing a three-dimensional article comprising at least one metal pattern, comprising the steps of: - step A of providing a flat substrate of a thermoforming material; - step B of forming on a surface of the flat substrate a temporary masking coating which adheres to said surface in order to obtain a masked substrate having at least one unmasked area; - step C of thermoforming the flat substrate to impart a substantially three-dimensional shape to the flat substrate; - a step D of metallizing the substrate to form a metal deposit on the substrate, at least on the unmasked areas; and E. removing said temporary masking coating.

[0015] Other characteristics and advantages of the invention will appear in more detail on reading the following description, with reference to the attached drawings, given purely as illustrative and non-limiting examples, in which: [Brief description of the drawings]

[0016] [Figure 1] In the context of a first example of implementation of the method according to the invention for manufacturing a three-dimensional RFID antenna, we show a flat substrate whose surface is covered with a temporary masking coating which adheres to said surface, thus forming a masked substrate having at least one unmasked area designed to receive a metal deposit. [Diagram 2] 2 shows a thermoformed mask substrate obtained after subjecting the masked flat substrate of FIG. 1 to a thermoforming step according to the present invention. [Diagram 3] In particular, it shows a thermoformed substrate provided on its surface with a solid silver metal pattern forming an RFID antenna electrode, obtained after the thermoformed mask substrate of FIG. 2 is subjected to a metallizing step and a step of removing the temporary masking coating according to the present invention. [Figure 4] In the context of a second example of implementation of the method according to the invention for producing a three-dimensional article with a decorative metal pattern, we show a flat substrate whose surface is covered with a temporary masking coating which adheres to said surface, thus forming a masked substrate having at least one unmasked area designed to receive a metal deposit. [Diagram 5] 5 shows a metallized masked substrate obtained after subjecting the masked flat substrate of FIG. 4 to a metallizing step and a step of removing the temporary masking coating according to the present invention. [Figure 6]6 shows a thermoformed metallized substrate having a plurality of decorative metallic patterns of solid silver on its surface, obtained after subjecting the metallized masked flat substrate of FIG. 5 to a thermoforming step according to the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] The present invention relates to a method for manufacturing a three-dimensional article comprising at least one metal pattern (or "metallized pattern"). As used herein, "three-dimensional" means a physical object that expands in space substantially in three dimensions along a non-negligible distance from one another. The shape and size of the metal pattern(s) are not particularly limited and may depend in particular on the intended use of the three-dimensional article and the metal pattern(s) carried by the three-dimensional article. Advantageously, the associated metal pattern(s) are decorative and / or functional, and thus form or contribute to form one or more graphic and / or textual information items that identify, for example and without limitation, one or more printed circuits, one or more integrated circuits on a semiconductive substrate, one or more sensor / detector electrodes, one or more electrodes of an electric heater / defroster, one or more radio frequency antennas (WiFi, RFID, etc.), one or more coding pictograms that can be read by an electronic device, a product incorporated or associated with said three-dimensional article, in particular a commercial product, such as a visual or decorative design on packaging, on an automotive product.

[0018] The manufacturing method according to the invention comprises at least the following steps: Step A of providing a flat substrate of thermoforming material; and step B of forming on the surface of the flat substrate (i.e. at least one side surface of the latter) a temporary masking coating adhering to said surface ("selective" temporary masking coating), in order to obtain a masked substrate having at least one unmasked area. Advantageously, said unmasked area is the area of ​​the surface of said flat substrate carrying the temporary masking coating (e.g. not the area of ​​the surface of the flat substrate opposite to the side carrying the temporary masking coating). Step C. thermoforming the flat substrate to impart a substantially three-dimensional shape to the flat substrate; Step D of metallizing the substrate and forming a metal deposit on the substrate, thus at least on the unmasked areas; Step E of removing said temporary masking coating, which is preferably the complete removal of said temporary masking coating, so that the three-dimensional article obtained at the end of the manufacturing method is advantageously completely devoid of said temporary masking coating.

[0019] Thanks to the method according to the invention, which ingeniously proposes to form a temporary (selective) masking coating adhering to the surface of a flat substrate of a thermoforming material before the step of thermoforming this flat substrate in order to perform a selective metallization of the substrate, it is therefore advantageously possible to produce three-dimensional articles with decorative and / or functional metal pattern(s) in a wide variety of shapes and geometries in a particularly simple and efficient manner. It is therefore advantageously possible to produce articles in a particularly simple and efficient manner, in particular with a non-flat three-dimensional shape of the substrate as well as the decorative and / or functional metal pattern(s). In fact, it is in fact much easier to perform a temporary masking on a flat substrate than on a three-dimensional substrate with a particularly complex shape / geometry, and the use of such a temporary masking coating then makes it possible to easily and precisely metallize a wide variety of substrates of a thermoforming material according to the multiple possible metallization techniques.

[0020] The invention covers various embodiments, as will become clear from the following, which are based on the general principle of using a (selective) temporary masking coating formed on a flat substrate and adhering to the surface of the flat substrate to define certain areas of the substrate carrying one or more metal patterns at the end of the method. In some cases, the temporary masking coating may be intended to allow selective activation of the substrate surface, so that only at least one area of ​​the substrate surface not masked by the temporary masking coating is activated and can receive a metal deposit during a metallization step D to form one or more metal patterns. In other cases, particularly when there is no need to activate the substrate surface for subsequent metallization, the metallization step D may be a step of metallizing the masked substrate to form metal deposits on the masked substrate at least on said unmasked areas. At the end of a step E of removing the temporary masking coating, only said unmasked areas carry metal deposits that form or are intended to form the desired metal pattern(s).

[0021] The method may further comprise all or some of the following additional steps, in particular (not necessarily in the following order): At least one step F of preparing a substrate surface, A step G of modelling the deformation of the flat substrate in the thermoforming step C and representing the metal pattern(s) obtained on the surface of the thermoformed substrate to define a two-dimensional masking pattern on which a temporary masking coating is subsequently formed on the flat substrate surface in step B; a step H of activating the substrate surface, in particular the unmasked area(s) intended to carry the metal pattern(s), Step I, rinsing the surface of the metallized substrate; Step J of drying the surface of the metallized substrate; one or more steps K, L, M of finishing the metallized substrate surface and / or more specifically the metal deposit or the metal pattern(s) formed on this surface, Step N of overmolding the thermoformed substrate; Step O. Assembling Additional Components

[0022] Within the meaning of the present invention, a "flat substrate" advantageously means a substrate of approximately substantially two-dimensional shape, i.e. a substrate that essentially extends in two of the three directions in space and to a lesser extent in the third direction in space. Typically, such a flat substrate can therefore take the shape of a film, a sheet or a plate. A "thermoforming material" advantageously means a material that can be shaped, deformed by being heated, i.e. a material that can be given a certain shape after being heated to an appropriate temperature (forming temperature) to soften it, and that after cooling and hardening, maintains the shape it has been given. If a flat substrate does not already exist before the implementation of the method according to the invention, step A of providing a flat substrate (hereinafter abbreviated as "step A") can comprise the manufacture of such a flat substrate from a selected thermoforming material. In general, according to the intended application, the flat substrate can be made of a non-conductive / dielectric thermoforming material, a semi-conductive thermoforming material or a conductive thermoforming material (either inherently or as a result of a treatment that has made it conductive).

[0023] Step B of forming a temporary masking coating (or "temporary masking coating") (hereafter abbreviated as "step B"), as introduced above, aims to define one or more specific areas on the substrate surface that are not masked by the temporary masking coating but that will carry the desired metal pattern(s) at the end of the metallization step D, the thermoforming step C and the step E of removing the temporary masking coating. Conversely, the substrate area(s) previously masked by the temporary masking coating are devoid of metal deposits and thus of metal pattern(s) at the end of the steps of metallization, thermoforming and removal of the temporary masking coating. Within the meaning of the present invention, a temporary masking coating is a coating that adheres to the substrate surface directly on the exposed surface of the substrate surface or indirectly, possibly via an intermediate coating that adheres to the substrate surface, to which the temporary masking coating adheres inversely. In any case, the temporary masking coating is therefore not a mechanical mask / stencil (such as, for example, a silk screen mask) that is simply stuck and applied in contact with said surface. It is further understood that the temporary masking coating is not intended to form or contribute to the formation of the metal deposit and metal pattern(s) described above.

[0024] The thermoforming step C (hereafter abbreviated as "step C") generally consists in hot deforming the flat substrate in an advantageously controlled manner in order to give said flat substrate an advantageously predefined substantially three-dimensional shape. In particular, step C aims at deforming the flat substrate at least locally and at least along a directional secant relative to the average plane of extension of said flat substrate.

[0025] As a variant (hereinafter "Variation V1"), the thermoforming step C is carried out before the metallization step D.

[0026] As a first sub-variant of this variant V1 (hereafter "variant V1a"), the thermoforming step C is further preferentially carried out before the step E of removing the temporary masking coating. In this case, step C is therefore a step of thermoforming the masked flat substrate not yet metallized, such that the flat substrate and the temporary masking coating are simultaneously thermoformed (or thermodeformed) before carrying out the step D of metallizing the thermoformed masked substrate. For this purpose, the temporary masking coating is therefore advantageously itself thermoformable, or at least thermodeformable, so that it is able to undergo the elongation of the flat substrate and thus follow the deformation, while adhering to the surface of the flat substrate during the thermoforming step C. The temporary masking coating is therefore advantageously designed in such a way that it can undergo the conditions for carrying out the step C of thermoforming the flat substrate without significantly degrading its function of masking the surface of the flat substrate, in particular with regard to its ability to elongate / deform without breaking. Thus, while the shape and / or surface area of ​​the unmasked region(s) may be altered by the thermoforming step C, the temporary masking coating nevertheless remains substantially tacky and film-formed, so that, in particular, additional unmasked regions are not inadvertently created by deformation of the temporary masking coating during the thermoforming step C. For simplicity, "unmasked region(s)" refers hereinafter independently to one or more unmasked regions of the masked substrate, whether or not the masked substrate has been thermoformed.

[0027] As a second sub-variant of this variant V1 ("Variant V1b"), step C is carried out after step E of removing the temporary masking coating, for example if said temporary masking coating is intended to enable selective activation of the substrate surface in an activation step H prior to the metallization step D. Step C is therefore a step of thermoforming a flat substrate, devoid of said temporary masking coating and not yet metallized, before carrying out step D of metallizing the thus thermoformed mask substrate.

[0028] In this variant V1, insofar as the metal deposit is formed on the substrate surface after the latter has been thermoformed, the metal deposit is therefore not subjected to the mechanical deformations and warming that the flat substrate is subjected to in the thermoforming step C. It is therefore advantageously possible to produce three-dimensional articles with particularly pronounced and / or complex shapes and geometries, and thus for that purpose, step C implies a significant deformation of the flat substrate during thermoforming, without the risk of resulting in a deterioration of the quality of the metal deposit, in particular its properties with regard to electrical conductivity (delamination, (micro)cracks, etc.). It is particularly advantageously possible to subject the flat substrate to deformation rates of 200% or more in the thermoforming step C. Such a variant V1 is particularly advantageous when it is desired to obtain a three-dimensional article comprising one or more metal patterns for functional purposes, such as forming one or more conductive metal tracks of a printed circuit, one or more sensor / detector electrodes or one or more radio frequency antennas.

[0029] As another variant (hereafter "variant V2"), a thermoforming step C is carried out after the metallization step D. In this variant V2, step C is a step of thermoforming the metallized flat substrate, so that the flat substrate and the metal deposit formed on its surface are simultaneously subjected to deformation. It is conceivable that a temporary masking coating is present on the surface of the flat substrate during the thermoforming step C ("variant V2a>>), but this is not strictly necessary. On the contrary, in this variant V2, it is even more advantageous that a step E of removing the temporary masking coating is carried out before the thermoforming step C ("variant V2b"), in order to avoid that deformation of the temporary masking coating possibly degrades the metal deposit.

[0030] Thus, in this variant V2, both the temporary masking coating formation step B and the metallization step D are carried out on a flat substrate. The implementation of these steps B and D is therefore simplified, since said steps B and D can be easily carried out online in an industrial context. Nevertheless, this variant V2 is preferably maintained for the manufacture of three-dimensional articles that require limited deformation of the metallized substrate in the thermoforming step C, in order to limit the risk of breakage of the metal pattern(s) or deterioration of the metal deposit quality leading to non-uniform conductive properties during thermoforming, and / or for the manufacture of three-dimensional articles in which the metal pattern(s) are decorative in nature.

[0031] The metallization step D (hereafter abbreviated as "step D") carried out after step B consists of forming a metal deposit intended to form all or part of the desired metal pattern(s) (i.e., for example, alone or possibly in combination with a complementary metal deposit) on the substrate surface and at least on the area(s) not masked by the temporary masking coating or on one or more substrate areas corresponding to the areas not masked by the temporary masking coating. As used herein, "metal deposit" generally means a deposit, layer comprising or formed from at least one metal or metal substance, at least one mixture of elemental metals, at least one metal alloy and / or at least one metal oxide, understood herein as at least one elemental metal (or "elementary single entity").

[0032] Advantageously, the metallization step D is carried out in such a way that the metal deposit obtained at the end of the latter comprises at least one metal (or "metallic substance") chosen from the group comprising elemental metals such as elemental metals, such as silver Ag, gold Au, nickel Ni, copper Cu, iron Fe, stain Sn, cobalt Co, alloys of these latter, mixtures of two or more of these elemental metals, or one or more oxides of at least one of these elemental metals.

[0033] Advantageously, in particular with regard to the conductive properties and / or with regard to the decorative properties of the metal pattern(s) (for example the "mirror" effect), the metallization step D is carried out in such a way that the metal deposit is made of solid metal filled with additional particles (or "fillers"), which may possibly be organic or inorganic. In this case, the metal deposit is therefore essentially, if not completely, formed of metal (or "metallic substance"), as defined herein above, within the scope of unavoidable non-metallic impurities. Thus, "metal deposit of solid metal" here particularly advantageously means that the metal deposit is advantageously devoid of a polymer matrix. This makes it possible to obtain metal patterns whose properties remain particularly stable over time, unlike patterns comprising a polymer matrix in which metal particles are dispersed, said polymer matrix tending to decompose gradually, for example under the influence of light, heat, etc., thus resulting in drifts in the properties of the metal pattern over time. Advantageously, the solid metal can be made of a single elemental metal (typically more than 90%, preferably more than 95%, even more preferably more than 98%). Thus, for example, the metal deposit can be formed from pure elemental metal, such as pure silver Ag (preferably more than 95%, more preferably more than 98%), and optionally additional particles. In some cases, the solid metal forms a solid (metallic) matrix in which the additional particles are dispersed. The additional particles are preferentially selected with a characteristic size of less than 100 μm. In general, the implementation of such additional particles aims to modify the physical properties (i.e. mechanical / tribological, electrical and / or optical properties) and / or the inherent chemical properties of the filled solid metal. Non-limiting examples of additional particles that are likely to be included alone or in admixture in the metal deposit of solid metal are particles of diamond carbon, particles of silicon carbide SiC, particles of molybdenum disulfide MoS2, particles of one or more rare earths or rare earth oxides, particles of graphene, particles of fluoropolymers (e.g. polytetrafluoroethylene (PTFE) etc.), particles of elemental metal or metal oxide(s), etc.

[0034] The metal deposit may be monolayer or multilayer, depending on the desired properties and the intended application of the metal pattern(s). Advantageously, step D is performed in such a way that the metal deposit has, at the end of the metallization step D, a thickness between 10 nm and 5 μm, preferably between 10 nm and 1 μm, and even more preferably between 10 nm and 500 nm. According to a variant, step D is performed in such a way that the thickness of the metal deposit obtained at the end of step D is substantially constant over the entire extension of said metal deposit, i.e. the thickness is substantially the same at any point of the metal deposit. It is thus possible to obtain one (or several) metal patterns having a substantially constant thickness over the entire extent of the metal pattern(s). According to another variant, step D is performed in such a way that the thickness of the metal deposit obtained at the end of step D is variable over the extent of said metal deposit (though preferentially remaining within the abovementioned values), i.e. the metal deposit has at least a first and a second region that are different from each other and the thickness of the metal deposit increases or conversely decreases (thickness gradient) from said first region to said second region. Such thickness variations of the metal deposit therefore advantageously make it possible to obtain one (or more) metal patterns defining areas of different electrical conductivity or resistivity, or different transparency or reflectivity to electromagnetic waves (e.g. visible light, IR or UV, radio frequency waves, etc.), which may be of particular importance depending on the intended functional and / or decorative application.

[0035] Different metallization methods, in particular different so-called "wet" or "dry" methods, can be contemplated for carrying out the metallization step D. The main so-called "dry" methods contemplated here include "physical vapor deposition" (PVD) and "chemical vapor deposition" (CVD) techniques. However, these techniques have the major drawback of having to evacuate the substrate in order to carry out the metallization. It is therefore preferred that the metallization step D implements one or more so-called "wet" metallization methods, electrolytic or chemical (electroless), which are generally easier and cheaper to implement, in particular in the context of industrial manufacturing, from one or more suitable metallization solutions.

[0036] Thus, in an advantageous variant, the metallization step D is carried out by (chemical) electroless deposition from one or more metallization solutions (or "redox solutions") advantageously comprising at least one metal in the form of a metal cation (i.e. a metal in the form of a cation forming an oxidizing agent) and at least one reducing agent adapted to convert the metal cation into a metal. Said at least one metal cation can advantageously be obtained by liquid-phase dissolution of at least one corresponding metal salt.

[0037] According to a first embodiment of this electroless variant, the abovementioned electroless deposition (or "metallization") is more particularly carried out by spraying the metallization solution(s) in the form of one or more aerosols. In this case, the method according to the invention optionally comprises, before said metallization step D, at least one of the following additional steps: a treatment step P for increasing the surface energy of the substrate, recognizing that if the method includes an activation step H, such a treatment step P for increasing the surface energy of the substrate may possibly be provided before said activation step H; Step Q of wetting the substrate surface; Step R: Rinse the substrate surface.

[0038] The treatment step P for increasing the surface energy of the substrate may possibly be comparable to the step F of preparing the substrate surface.

[0039] This embodiment using a spray of aerosol(s) is particularly interesting in that, in addition to the excellent properties of the metal deposit that can be so formed, it allows a simple and rapid metallization of substrates of any size, especially substrates of large size. Moreover, it is particularly suitable when the metallization step D is carried out after the thermoforming step C, and thus the surface to be metallized is not flat but is deformed on the contrary. In addition, this embodiment makes it possible to obtain in a particularly simple manner metal deposits whose thickness is variable depending on the extent of said metal deposit, as contemplated above. Moreover, this embodiment using a spray of aerosol(s) advantageously makes it possible to form in a simple and efficient manner metal deposits of solid dense metal (and therefore substantially free of porosity, unlike porous metal deposits formed from agglomerates of metal particles), which is particularly interesting when it is desired to obtain metal patterns with particularly good electrical properties.

[0040] According to a second embodiment of this electroless variant, the electroless deposition described above is an autocatalytic (or "non-electrolytic") chemical deposition (or "metallization") carried out by immersing the substrate in one or more metallization solutions, which optionally contain, in addition to one or more metal cations and one or more reducing agents, one or more complexing agents, one or more stabilizing agents and any other additives, such as surfactants. In this case, the method advantageously comprises a step H of activating the substrate surface before the metallization step D, and optionally before said activation step H, at least one of the following steps, preferably in the following order: a satin finishing step S, preferably implemented between the step B of forming the temporary masking coating and the activation step H; When implementing such a satin finish step S, a step T is performed of rinsing the substrate surface.

[0041] As another wet variant, the metallization step D may possibly be carried out by electrolytic deposition (or "electrodeposition" or "galvanostegy", also known as electroplating). Such electrolytic deposition (or "metallization") is based on an oxidation-reduction reaction using an electric current, typically based on a metallization solution containing at least one metal in cationic form in an aqueous medium. An electric current is applied between the substrate to be metallized and a counter electrode. The metal cations are then reduced at the substrate surface to form a metal deposit. However, insofar as only the single case in which the thermoforming material of the substrate is (electrically) conductive is considered, such a metallization method by electrolytic deposition is less preferred than the two methods mentioned above, since it strongly limits the choice of thermoforming material, especially with the exception of most thermoforming polymer materials.

[0042] In some cases, the metallization step D can be carried out, on the one hand, according to the first embodiment of the electroless metallization variant described above (i.e. by spraying of an aerosol(s)) and, on the other hand, according to the second embodiment of the electroless metallization variant described above (i.e. by immersion) and / or according to the electrolytic deposition variant described above.

[0043] As is evident from the above, the step E of removing the temporary masking coating (hereinafter abbreviated as "step E") aims to remove the temporary masking coating present on the substrate surface.

[0044] Thus, step E is Prior to the metallization step D, in particular if the method comprises a step H of activating the substrate surface prior to the metallization step D, and the temporary masking coating is intended to allow selective activation of the substrate surface, or after metallization step D, Or, preferentially, it can be performed either during the metallization step D, or partially during and partially after the metallization step D, or partially before the metallization step D, partially during and partially after the metallization step D.

[0045] As preferentially proposed below, carrying out step E at least partially simultaneously with metallization step D advantageously contributes to accelerating and simplifying the implementation of the method according to the invention by limiting the number of successive steps required.

[0046] Advantageously, the step E of removing the temporary masking coating is at least partly carried out by chemical, non-mechanical means in order to remove said temporary masking coating from the substrate surface in a simple and clean way, by limiting the risks of compromising the thinness and precision of the obtained metal pattern(s), especially when said step E is carried out after the thermoforming step C.

[0047] Thus, step E of removing the temporary masking coating advantageously comprises at least one operation of dissolving (at least partially) the temporary masking coating using at least one solvent implemented in the present method. In some cases, step E may advantageously essentially consist of dissolving (at least partially) the temporary masking coating using at least one solvent implemented in the present method. In this specification, "dissolving using at least one solvent" means total or partial disintegration, decomposition or loss of cohesion of the temporary masking coating under the action of a specific fluid (preferably a liquid) selected for its specific chemical aggressiveness towards the temporary masking coating, likely allowing its disintegration, separation and expulsion from the substrate surface. This may therefore be, but is not necessarily, a mechanism of dissolving in a solvent in the strict chemical sense. Preferably, said temporary masking coating is alkali-soluble (or at least alkali-sensitive) so that it can be preferentially dissolved by the alkaline solvent implemented in the present method.

[0048] Step E may optionally comprise, prior to said dissolving operation of the temporary masking coating, an exposure operation under actinic radiation (e.g. under UV light) and / or a heat treatment operation of the temporary masking coating in order to weaken the temporary masking coating and / or to facilitate the dissolving of the temporary masking coating. Step E may optionally comprise, after such a dissolving operation, an operation consisting in particular of promoting the evacuation of the dissolved temporary masking coating and / or any debris that is not completely dissolved from the temporary masking coating, of carrying it in a liquid phase and / or of carrying it mechanically using a gas (preferably air).

[0049] In the above cases in which step E is carried out in a metallization step D, or partly in a metallization step D and partly after a metallization step D, or partly before, partly during and partly after a metallization step D, said solvent for removing the temporary masking coating by dissolution is preferentially contained in at least the metallization solution (or one of the metallization solutions) implemented in step D. It is therefore an operation of dissolving the temporary masking coating with at least one solvent implemented in step D. The duration of formation of the metal deposit in said metallization step D is then preferably selected to be equal to or less than the time necessary to dissolve the temporary masking coating under the action of said solvent.

[0050] Complementarily or alternatively, the method may include a step I of rinsing the metallized substrate surface, and a solvent for removing the temporary masking coating by dissolution may be included in the rinsing liquid implemented in step I above.

[0051] Nevertheless, although less preferentially, step E may be carried out by non-chemical means, for example by laser ablation, using a pressurized gas jet, or by any known suitable mechanical means.

[0052] This being clear, we now explain in detail some aspects of the above steps. -Step A- providing a flat substrate made of a thermoforming material

[0053] Although it is conceivable to implement a flat substrate made of glass (minerals) or metal, the flat substrate is preferably made of a thermoformable polymer material (thermoplastic material), whether filled or not, or a composite polymer-matrix thermoformable material. Indeed, polymer or polymer-matrix thermoformable materials are particularly easy to implement in general, due to their softening temperatures, which are much lower than those of glass or most metals. Possible thermoformable polymer materials include, by way of non-limiting examples, polystyrene (PS), "impact" polystyrene (SB / HIPS), polyethylene (PE), polypropylene (PP), polycarbonate (PC), acrylonitrile-butadiene-styrene (ABS), polyvinyl chloride (PVC), polymethyl methacrylate (PMMA), or thermoplastic polyesters such as polylactic acid (PLA), polyethylene terephthalate (PET) and glycolated polyethylene terephthalate (PETG). If the flat substrate is a composite polymer-matrix thermoformable material, the polymer of the polymer matrix can be selected, for example, from among the thermoformable polymer materials listed above.

[0054] More generally, the thermoforming material of the flat substrate may be a single material or, conversely, a composite material. The flat substrate may be single layer or, in some cases, multi-layered.

[0055] Advantageously, said flat substrate may be a film, sheet or plate of a thermoformable polymer material or a composite polymer-matrix thermoformable material with a thickness of between 8 μm and 15 mm, more preferably between 25 μm and 10 mm, which allows for easy subsequent handling and thermoforming.

[0056] Depending on the material and thickness selected, the flat substrate can be substantially rigid or, on the contrary, flexible. In practice, however, in particular to facilitate the industrial implementation of the method, it is preferred that the flat substrate is flexible, i.e. it can be advantageously bent or folded only by human force without breaking, deforming or irreversibly degrading. The flat substrate can thus, for example, be advantageously provided continuously from a coil of wound substrate and then wound again on a coil at the end of step B of forming a temporary masking coating or at the end of metallization step D, if metallization step D is carried out before thermoforming step C (variant V2) (so-called "roll-to-roll" / "R2R" method). In contrast, by "rigid substrate" is meant a substrate that cannot be bent or folded only by human force without breaking or irreversibly degrading. - Step F - Preparing the substrate surface

[0057] As introduced above, the method may comprise one or more steps F of preparing the substrate surface, the purpose of which is to modify certain properties of the substrate surface in order to implement one or more latter steps of the method. This may be one or more steps of preparing the surface of a flat substrate, carried out before the thermoforming step D, and / or one or more steps of preparing the surface of a thermoformed substrate, carried out after the thermoforming step C.

[0058] Moreover, such step F may be performed before or after step B of forming the temporary masking coating. In certain cases, preparing the surface of the flat substrate before forming the temporary masking coating allows the temporary masking coating to not undergo physicochemical modifications, which would likely result in excessively high adhesion of the flat substrate to the surface of the flat substrate, making subsequent removal of the temporary masking coating more difficult. In other cases, preparing the surface of the flat substrate may be performed after forming the temporary masking coating, on the contrary, to enhance the cohesion, adhesion and possibly slow down the removal of the temporary masking coating.

[0059] Step F may include cleaning and / or degreasing the substrate surface by any known suitable product. In addition to or instead of such cleaning / degreasing operations, step F may include depositing a possibly pigmented / pigmented varnish, e.g. a UV crosslinking varnish applied by spraying, on the substrate surface by any known suitable means, such as a compressed air spray gun (e.g. a high volume low pressure (HVLP) spray gun).

[0060] Optionally, step F may include or correspond to at least a treatment for increasing the surface energy of the substrate surface (step P). -Step B - Forming a temporary masking coating

[0061] The practical arrangements for carrying out step B may depend in particular on the nature of the thermoforming material of the flat substrate, on the desired precision for defining the unmasked area(s), and potentially, in particular in the case of the above-mentioned sub-variant V1a, on the conditions of the thermoforming step C to which the flat substrate and the temporary masking coating are subsequently subjected in the thermoforming step C (in particular with regard to thermoforming and deformation ratio).

[0062] Said step B of forming a temporary masking coating preferentially comprises: selectively depositing a layer of a liquid or paste masking composition onto a flat substrate surface by any known suitable application technique, such as screen printing, pad printing, flexography, rotogravure printing, and / or direct printing (e.g., drop printing or "ink jet"); Optionally followed by drying and / or curing the so-deposited layer of masking composition.

[0063] Depending on the formulation of the selected masking composition, the latter drying and / or curing may involve a drying / desolvation operation, possibly under the effect of heat input, or a polymerization / crosslinking of the deposited masking composition under the effect of heat input and / or under the action of actinic radiation (e.g., by exposure to ultraviolet (UV) light). Such drying and / or curing of the deposited masking composition layer is particularly advantageous to avoid uncontrolled spreading of the masking composition, which, depending on the flowability of the masking composition, is likely to impair the geometric definition of the unmasked area(s).

[0064] Alternatively, in a more complex and therefore less preferred manner, step B may be depositing (non-selectively) the liquid or paste masking composition onto a flat substrate surface, e.g., by immersion, spraying, or any other known suitable non-selective deposition technique; Optionally thereafter, drying and / or curing the so deposited masking composition layer; Thereafter, the formed temporary masking coating may be selectively removed to locally create one (or more) unmasked areas on the flat substrate surface.

[0065] Optionally, the masking composition is deposited on the surface of a flat substrate in step B according to a predefined two-dimensional masking pattern in step G, as described below.

[0066] The masking composition may be selected to be substantially colorless or, conversely, colored / pigmented. Masking compositions that include dyes / pigments may, in some cases, allow for easier visualization of the temporary protective coating formed on the surface of a flat substrate, which may be practical in some cases.

[0067] Preferably, step B is carried out in such a way that the temporary masking coating, at the end of step B forming the latter (thus, possibly after drying and / or curing of the deposited masking composition layer), has a thickness of between 100 nm and 50 μm, preferably between 500 nm and 20 μm, even more preferably between 1 μm and 10 μm. Such a thickness makes it possible to obtain a sufficient barrier effect at the surface of the substrate areas that are not intended to subsequently carry the metal pattern(s). Moreover, such a thickness contributes advantageously, possibly (variant V1a), to the ability of the temporary masking coating to undergo a thermoforming step C without suffering significant damage. In another variant, step B is carried out in such a way that, at the end of step B, the thickness of the temporary masking coating is substantially constant along the entire extension of the temporary masking coating, i.e. the thickness of the temporary masking coating is substantially identical at any point of said temporary masking coating. As another variant, step B is carried out in such a way that at the end of step B the thickness of the temporary masking coating is variable over the range of the temporary masking coating (while preferentially remaining within the above-mentioned value ranges), i.e. the temporary masking coating has at least a first and a second portion which differ from each other and the thickness of the first portion differs from the thickness of the second portion. Such thickness differences of the temporary masking coating, preferably within the above-mentioned value ranges, can be of interest, especially in the case of variant V1, to locally adapt the thickness of the temporary masking coating to the deformation amplitude to which a given area of ​​the (masked) substrate is subjected during the thermoforming step C.

[0068] It should be noted that since the temporary masking coating formation step B is carried out on the (flat) substrate before the thermoforming step C, the temporary masking coating is thus not formed at the end of step B, or at least, although not necessarily, an exact negative of the metal pattern(s) finely obtained on the surface of the thermoformed substrate is formed. In fact, according to the above-mentioned sub-variant V1a, the temporary masking coating itself undergoes a deformation during step C, so that it is the deformed temporary masking coating obtained at the end of step C, which advantageously corresponds to the negative of the metal pattern(s) then obtained. According to variant V2, the temporary masking coating may or may not be present on the substrate surface when the thermoforming step C is carried out. Thus, in the preferred case where a step E of removing the temporary masking coating is carried out before step C, the surface of the flat substrate is provided with one (or several) "raw" metal patterns which undergo deformation during the thermoforming step C in order to generate the desired metal pattern(s). The temporary masking coating therefore corresponds in this case to the negative of said "raw" metal pattern(s).

[0069] As described herein above, in the case of sub-variant V1a of variant V1, the temporary masking coating is advantageously designed to be thermoformable and to be able to undergo the conditions for carrying out step C of thermoforming the flat substrate without significantly deteriorating its function of masking the surface of the flat substrate, in particular in terms of its ability to stretch / deform without breaking and its heat resistance. Typically, the temporary masking coating is advantageously designed to have, at the forming temperature selected in particular for the thermoforming step C, a stretch / deformation ratio without breaking that is at least equal to the deformation ratio that it is desired to impart to the flat substrate in the thermoforming step.

[0070] Such a specific design can typically be achieved by making appropriate choices regarding the formulation of the masking composition, it being understood that the exact formulation of the masking composition may in fact depend on several factors, such as, in particular, the application mode of the masking composition onto the substrate, the nature of the thermoforming material of the substrate, the forming temperature at which the thermoforming step C is performed, the thickness of the thermal masking coating to be formed, the deformation ratio desired to be imparted to the flat substrate and the temporary masking coating in the thermoforming step C, etc. For example, such ability of the temporary masking coating to support the conditions for performing the step C of thermoforming the flat substrate can be imparted by selecting, in the formulation of the masking composition, a specific polymeric organic binder capable of forming a polymeric organic matrix with the desired ability of elongation / deformation without fracture and heat resistance.

[0071] The preferential solubility (or sensitivity) property of the temporary masking coating to the solvent implemented in the method, and more preferentially to at least the solvent contained in the metallization solution or one of the metallization solutions implemented in step D, can be imparted to the temporary masking coating by making selections with regard to the masking composition formulation, for example by selecting components such as a polymeric organic binder intended to form a polymeric organic matrix that are particularly dissolvable by the solvent in question, or at least less sensitive to the latter.

[0072] For example, the masking composition implemented in step B can include all or part of the following components (it being understood that the masking composition content of each component can depend, inter alia, on the application mode selected for the masking composition, as well as its potential drying / curing mode): A vehicle component, which may account for 20% to 70% of the total weight of the masking composition. The vehicle component may include an organic or aqueous solvent, a monomer, an oligomer, or a mixture of these compounds. Specifically, it solubilizes or suspends the remaining components described below. The vehicle component contributes to the viscosity and rheological properties of the masking composition, thus facilitating its application. It is intended to evaporate and thermally cure in the case of a masking composition, and / or crosslink in the case of a UV crosslinking masking composition, e.g. The binder component can represent 30% to 70% of the total weight of the masking composition. Advantageously, in the case of heat-drying masking compositions, it is intended to form an organic polymer matrix, which can be acrylic, polyester, vinyl, styrene or polyamide. In the case of UV-crosslinkable masking compositions, the binder component can be a mixture of acrylate, cationic or anionic monomers and oligomers, as well as the abovementioned polymers. The binder component can furthermore possibly play the role of a vehicle. The binder component supports its main properties, in particular adhesion to the substrate, resistance to abrasion, potential sensitivity to the solvents implemented in the method (e.g. alkali sensitivity) and the thermoforming step C, endowing the temporary masking coating with the potential ability to be thermally deformed without breaking during this latter step. A solid, organic or inorganic component that may represent 1% to 50% of the total weight of the masking composition. It may correspond to a mineral or organic, possibly fibrous filler. It may impart or contribute to impart color, specific rheological properties and resistance to abrasion to the masking composition and / or the temporary masking coating. One or more additives which may represent 0.01% to 10% of the total weight of the formulation. It may be one or more rheological additives, wetting agents, defoamers, dispersants, surfactants, stabilizers or colorants. Among other things, these additives make it possible to correct the rheology, the applicability and the wetting of the masking composition on the substrate, to accelerate or slow down the drying or hardening of the masking composition, to better disperse and stabilize the solid components, to color the masking composition or to improve certain properties of the temporary masking coating, for example its resistance or gloss. Optionally, one or more photoinitiators, which may represent 5% to 15% of the total weight of the masking composition. In the case of UV-curable masking compositions, they are capable of crosslinking the monomers and oligomers. They may be radical, cationic or anionic.

[0073] Non-limiting examples of vehicle components include water, butanol, methoxypropanol, ethyl acetate, butyl acetate, cyclohexane, 2-butoxyethanol acetate, 2-methoxy-1-methylethyl acetate, propylene carbonate, isopropyl myristate, diethylene glycol monoethyl ether acetate, glycerol, hexane, methylcyclohexane, and the like, among monomers such as PETIA, HDDA, IBOA, TMPTA, TPGDA, HEMA, etc. Non-limiting examples of binder components include copolymers of vinyl acetate and vinyl chloride, acrylic resins, polyvinyl alcohol, polyvinylpyrrolidone, polyurethane, aliphatic urethane acrylates, polyester acrylates, polyesters, and the like. Non-limiting examples of solid components include silica, barium carbonate, barium sulfate, aluminum hydroxide, waxes, and the like. -Step G- of defining a two-dimensional masking pattern

[0074] In particular, when said at least one metal pattern is intended to play a functional role, especially in wireless or electronic applications, it may be important to provide a perfect control of the shape of the metal pattern obtained on the surface of the thermoformed substrate. Thus, the method according to the invention may advantageously comprise, before step B, a step G of defining a two-dimensional masking pattern, along which a temporary masking coating is formed on the surface of the flat substrate in said step B of forming a temporary masking coating by modeling the deformation of the flat substrate and possibly by modeling the deformation of the temporary masking coating during the thermoforming step C, representing (or modeling) said at least one metal pattern obtained. In other words, the definition of the two-dimensional masking pattern is performed by "reverse anamorphosis", along which a temporary masking coating is formed on the flat substrate surface in step B. This two-dimensional masking pattern allows to obtain the desired metal pattern(s) by predicting and compensating for the effects of the deformations generated by the thermoforming step C. The step of defining such a two-dimensional masking pattern can be carried out using commercially available computer software such as, for example, the software T-SIM® by SIMCON (formerly CADFLOW), the software PAM-FORM™ by ESI GROUP, the software solution ANAMAP™ by KALLISTO, or the software Thermo 3D™ by QUADRAXIS. -Step H: Activating the Substrate Surface-

[0075] Depending on the nature of the substrate, the nature of the metal deposit to be formed, and depending on the metallization method(s) used to perform metallization step D, a prior step of activating the substrate surface may be necessary to enable, or at least facilitate, the formation of the metal deposit on the substrate surface.

[0076] If the metallization step D is carried out by electroless deposition by spraying the metallization solution(s) in the form of an aerosol(s), such an activation (or at least "sensitization") step H may be necessary to deposit certain metals, in particular with the aim of promoting the redox reaction involved in step D. During step H, the substrate surface is contacted with at least one chemical sensitizing species, which is adsorbed on the substrate surface and subsequently promotes the metallization reaction.

[0077] Preferably, an activation step H is carried out after step B of forming the temporary masking coating and before step E of removing the temporary masking coating, so that the chemical sensitizing species or species are adsorbed to both the temporary masking coating and to the area(s) not masked or covered by the temporary masking coating.

[0078] In practice, step H is preferentially carried out by spraying the at least one sensitizing solution onto the substrate surface, and by any known suitable means, such as, for example, using a compressed air paint gun (e.g., a high volume, low pressure (HVLP) spray gun). Alternatively, step H can be carried out by immersing the substrate in the at least one sensitizing solution.

[0079] A first sensitizing solution, for example based on stannous chloride (SnCl2) or SnSO4 / H2SO4 / quinol / alcohol, is applied by spraying or immersion. The ions Sn 2+Palladium or silver-based solutions capable of reacting with the nucleation centers to form on the substrate surface, or ex situ formed PdSn colloidal solutions, are deposited in the same way. More precisely, reference can be made, for example, to "Metal Finishing Guidebook and Directory Issue", 1996, Metal Finishing publication, pages 354, 356 and 357; "Metallizing of Plastics" by H. Narcus, Reinhold Publishing Corporation, 1960, Chapter 2, page 21; or "Modern electroplating" by F. Lowenheim, John Wiley&Sons publication, 1974, Chapter 28, page 636. Advantageously, substrate surface sensitization is implemented using a stannous chloride-based sensitizing solution, for example according to the implementation described in document FR-2 763 962 B1. In this case, immediately after sensitization, a rinsing step is carried out, without intermediate steps, with a rinsing solution as described below. As a variant, substrate surface activation is implemented using a sensitizing solution, in particular palladium chloride, for example according to the implementation described in document FR-2 763 962 B1, in which case the activation step H is immediately followed by a rinsing step, without intermediate steps, using a rinsing liquid as shown in the examples below.

[0080] When the metallization step D is carried out by autocatalytic ("electroless") chemical deposition by immersion in one (or several) metallization solutions, such an activation step H, advantageously aimed at promoting the catalytic redox reactions involved in step D, is generally indispensable. It consists in depositing, on the surface of the masked substrate, a non-electrochemical metallization catalyst, for example a Sn / Pd type catalyst.

[0081] Preferably, an activation step H is carried out after the step B of forming the temporary masking coating and before the step E of removing the temporary masking coating, so that the catalyst is adsorbed both on the temporary masking coating and on the area(s) not masked or covered by the temporary masking coating.

[0082] Step H is preferably preceded by a satin finishing step S followed by a rinsing step T. Step S corresponds to a treatment for increasing the surface energy and / or for increasing the roughness of the substrate, which may be of the type described below for step P. In the case of autocatalytic chemical deposition, the satin finishing is preferably carried out by a physical treatment (corona discharge, plasma treatment, etc.) or a chemical treatment (for example sulfochromic or other treatment) in order to give sufficient adhesion to the metal deposit to be formed. The rinsing step T advantageously corresponds to a rinsing of the type described below for step R. - Step C - Thermoforming the flat substrate

[0083] Step C of thermoforming the flat substrate can advantageously be carried out by any known thermoforming means and techniques, obviously adapted to the substrate properties (nature of the thermoforming material, thickness of the flat substrate, etc.) and possibly to the inherent properties of the temporary masking coating and / or of the metal deposit or metal pattern(s) potentially present on the surface of the flat substrate to be thermoformed.

[0084] Typically, step C is carried out by heating the flat substrate, advantageously uniformly, by conduction and / or convection and / or radiation, until the thermoforming material of the flat substrate is heated to a forming temperature sufficient to make the flat substrate malleable. The forming temperature in question can obviously vary depending on the thermoforming material selected. In the case of thermoformable polymeric materials, the forming temperature is typically chosen at least equal to the glass transition temperature of the material considered, but nevertheless advantageously lower than the melting temperature of the material in question. Once made malleable, the flat substrate is pressed (or counter-shaped), advantageously by vacuum and / or pressure suction, against a male mold ("positive") or a female mold ("negative"), so that the flat substrate is deformed and conforms to the mold shape. The deformed substrate is then cooled, so that the thermoforming material hardens and maintains the shape given by the mold, after which the deformed substrate is removed from the mold. -Metallization Step D-

[0085] As introduced above, the metallization step D can be carried out after the thermoforming step C (variant V1) or conversely before the thermoforming step C (variant V2). -electroless deposition by projection in the form of aerosol(s)

[0086] A step P of treatment for increasing the surface energy of the substrate, a step Q of wetting the substrate surface and a step R of rinsing the substrate surface, which may possibly precede the activation step H or the metallization step D, are described below as a prelude to the description of the metallization step D according to the embodiments contemplated herein, the metallization being carried out by electroless (chemical) deposition by projection of one or more metallization solutions in the form of an aerosol(s). If step D is carried out after the thermoforming step C (variant V1), then said steps P, Q and R are preferentially carried out after said step C.

[0087] A step P of the treatment for increasing the energy of the substrate surface comprises: It can be carried out by a physical treatment, preferably chosen from the following physical treatments: flaming, plasma treatment, corona treatment, roughening (by sand blasting, shot blasting, etc.) and combinations thereof, and / or It can be carried out by a chemical treatment, preferably chosen among the following chemical treatments: application of a silane-based solution, surface depassivation using one or more acid solutions, rare earth oxide polishing, fluorination, acid or alkaline chemical attack to create micro-roughness, and combinations thereof.

[0088] More preferentially, the physical treatment is a flaming and / or a plasma treatment, especially when the flexible or rigid substrate is made of a thermoformable polymer material or a composite polymer-matrix thermoforming material. The flaming operation consists, for example, of passing the substrate to be metallized under a flame, the temperature of which is, for example, between 1200 ° C and 1700 ° C. The flaming duration is generally between 4 and 50 seconds. The flame is preferably obtained by burning a fuel, for example propane, in the presence of an oxidizing agent, such as oxygen. The plasma treatment corresponds, for example, to the passing of the substrate to be metallized in a plasma torch, for example those marketed by ACXYS® or PLASMATREAT®. More preferentially, the chemical treatment is a fluorination treatment, especially when the flexible or rigid substrate is made of a thermoformable polymer material or a composite polymer-matrix thermoforming material. The fluorination corresponds, for example, to contacting the substrate to be metallized with a gaseous solution based on an inert gas (argon) containing a fluorine additive, in an enclosure under reduced pressure. Such fluorination can be carried out, for example, using equipment of the type marketed by AIR LIQUIDE®.

[0089] In any case, these physical and / or chemical treatments for increasing the surface energy of the substrate must advantageously be carried out so that, at the end of step P, the surface energy of the substrate is greater than or equal to 50 dynes or less than or equal to 55 dynes, preferably greater than or equal to 60 dynes or greater than or equal to 65 dynes and even more preferentially greater than or equal to 70 dynes. Below these values, insufficient wetting of the substrate may become evident and the metal deposit obtained after metallization may have insufficient adhesion, gloss and reflection properties. The surface energy values ​​may be measured by techniques known to those skilled in the art, consisting, for example, of applying a particular solution on the substrate using a brush or a felt tip and measuring the shrinkage time of the solution thus applied.

[0090] The wetting step Q typically consists of coating the substrate surface with a liquid film, for example by spraying or evaporation / condensation of the wetting liquid, in order to facilitate the diffusion of the metallization solution(s) ("redox solution(s)"). The wetting liquid is preferably chosen in the following group: deionized or non-deionized water, optionally with the addition of one or more anionic, cationic or neutral surfactants, alcoholic solutions containing one or more alcohols (for example isopropanol, ethanol and their mixtures), and mixtures thereof. For example, deionized water with the addition of an anionic surfactant and ethanol can be chosen as the wetting solution. In the wetting variant, in which the wetting liquid is converted into a vapor and sprayed onto the substrate where the vapor is condensed, it is preferred that the liquid is essentially aqueous, for obvious reasons of industrial convenience. The wetting duration depends on the substrate surface considered and on the wetting liquid spray or evaporation / condensation rate. The wetting step Q can possibly be used instead of the activation step H.

[0091] Advantageously, the rinsing step R, like the other rinsing steps in the method, is distinct from step I or step T and consists in contacting all or part of the substrate surface with one or more rinsing liquids, preferably demineralized water, by spraying an aerosol of the rinsing liquid(s).

[0092] Step D of electroless (chemical) deposition metallization by spraying one (or several) metallization solutions in the form of an aerosol (or aerosols) advantageously relates to the methods described in documents FR-2 763 962 B1, EP-2 326 747 B1 or EP-2 318 564 B1.

[0093] The metallization step D is advantageously carried out by electroless deposition using (at least) one of the following: only one metallization solution comprising said at least one metal in metal cation form and said at least one reducing agent adapted to convert the metal cations to metal, or two different solutions: a first solution containing at least one metal in the form of a metal cation (the oxidizing agent(s)) (the "oxidizing solution") and a second solution containing one or more reducing agents (the "reducing solution"); Or, a plurality of separate solutions, each of which may contain either at least one metal in metal cation form (oxidizing agent(s)) or one or more reducing agents, provided that at least one of the solutions (the "oxidizing solution") contains at least one metal in metal cation form and at least another one of the solutions (the "reducing solution") contains one or more reducing agents.

[0094] The reducing agent is advantageously selected to be strong enough to reduce the metal cation to the metal, i.e. the selected standard redox potential of the reducing agent's oxidizing / reducing couple is lower than the standard redox potential of the oxidizing agent's oxidizing / reducing couple (Gamma rule). Such electroless modification is particularly advantageous in that it allows the formation of solid metal deposits as contemplated hereinabove on the surface of substrates, whether conductive or not, independently, and furthermore with thicknesses advantageously included in the range of values ​​indicated above.

[0095] During the metallization step D, the metallization solution(s) are sprayed in the form of an aerosol(s) onto the masked substrate, in particular onto at least the unmasked substrate area(s) of the masked substrate. As used herein, "aerosol" means a set of fine particles of the metallization solution(s) suspended in a gaseous medium (for example air). It may therefore advantageously be a mist of droplets of less than 100 μm, preferably less than 60 μm, more preferentially between 0.1 μm and 50 μm, obtained by atomization and / or atomization of the metallization solution(s).

[0096] Advantageously, the metallization solution(s) ("redox solution(s)") can be obtained from a solution, advantageously aqueous, of one or more oxidized metal cations (usually obtained by dissolving one or more corresponding metal salts) and one or more reducing components, preferably by dilution of a concentrated stock solution, the diluent being preferably demineralized water. Depending on the nature of the metal deposit to be formed, the spraying of the metal solution(s) can be carried out continuously, i.e. all at once, or discontinuously with alternating spraying phases and relaxation times. For example, in the case of silver-based metal deposits, the spraying is preferentially carried out continuously. For example, in the case of nickel-based metal deposits, the spraying is preferentially carried out discontinuously with alternating spraying phases and relaxation times. Depending on the thickness of the desired metal deposit, the spraying duration can advantageously be in the range of 1 dm 2The spray time may vary between 0.5 and 200 seconds, preferably between 1 and 50 seconds, and even more preferentially between 2 and 30 seconds for the substrate surface area to be metallized. Using adjustment of the spray cone, the metallization solution(s) can be sprayed over larger or smaller areas of the substrate. By adjusting the spray duration and / or the amount of metallization solution(s) sprayed locally, it is possible to obtain a gradient in the metal deposit thickness, as described above.

[0097] The spraying of the metallization solution(s) can be carried out using any suitable spraying means, preferably using one or more compressed air spray guns, for example one or more high volume low pressure (HVLP) spray guns. Advantageously, the spraying means and the substrate can be set in relative motion (translation and / or rotation) to allow in-line metallization and / or to ensure good spraying of all areas to be metallized on the substrate, especially if the substrate has been thermoformed prior to the metallization step D.

[0098] According to a first spraying method, one or more metal cation solutions ("oxidizing solution(s)") and one or more reducing agent solutions ("reducing solution(s)") are sprayed simultaneously and successively in the form of one or more aerosols onto the surface to be treated. In this case, mixing of the oxidizing and reducing solutions may take place immediately before the formation of the aerosol or by the merging of the aerosols generated from the oxidizing and reducing solutions, preferably before they come into contact with the substrate surface to be metallized. According to a second spraying method, one or more metal cation solutions ("oxidizing solution(s)") and then one or more reducing agent solutions ("reducing solution(s)") are sprayed simultaneously and successively onto the surface to be treated in the form of one or more aerosols. In the first method, the redox solution is sprayed continuously using one or more aerosols. In other words, the spraying of the redox solution is carried out by separately spraying one or more solutions of one or more metal oxidizing agents and one or more solutions of one or more reducing agents. This second possibility corresponds to the alternating spraying of the reducing solution(s) and the metal cation solution(s). Within the framework of the second projection method, the association of several oxidizing metal cations to form multiple layers of different metals or alloys is such that the different metal cations are sprayed spontaneously, preferably separately from the reducing agents, but separately from each other in succession.

[0099] According to a third spraying method, a metastabilized metallization solution comprising a mixture of said at least one metal in metal cation form ("oxidizing agent(s)") and said at least one reducing agent is sprayed in aerosol form, then after spraying on the substrate surface, the metallization solution is activated so as to cause the conversion of the metallization cation(s) to metal, preferably by contact with a primer, advantageously added using one or more aerosols before, during and after spraying of the metallization solution. The priming or activation of the redox reaction is then possibly obtained by any suitable physical (temperature, UV, etc.) or chemical means.

[0100] To prepare the metallization solution(s) to be sprayed in the form of the aerosol(s), water appears as the most suitable solvent, although organic solvents may also be used.

[0101] The concentration(s) of the metal salt(s) in the oxidizing solution(s) to be sprayed is preferentially between 0.1 g / l and 100 g / l, more preferably between 1 g / l and 60 g / l. Optionally, the concentration(s) of the metal salt(s) in the stock solution(s) is preferably between 0.5 g / l and 500 g / l, or the dilution factor of the stock solution(s) is preferentially between 5 and 5000. Advantageously, the metal salt is chosen from silver nitrate, nickel sulfate, copper sulfate, tin chloride, perchloric acid, iron chloride, cobalt chloride, and mixtures thereof.

[0102] The selection of the reducing agent(s) is preferably made among the following components: boron hydride, dimethylaminoborane, hydrazine, sodium hypophosphite, formaldehyde, lithium aluminum hydride, reducing sugars, such as glucose derivatives or sodium erythorbate, and mixtures thereof. The selection of the reducing agent must take into account the pH and the properties required for the metal deposit. These routine adjustments are within the scope of the skilled person. The concentration(s) in the metal salt(s) of the reducing solution(s) to be sprayed is preferentially between 0.1 g / l and 100 g / l, more preferably between 1 g / l and 60 g / l. In some cases, the concentration(s) in the reducing agent(s) of the stock solution(s) is preferably between 0.5 g / l and 250 g / l, or the dilution factor of the stock solution(s) is preferentially between 5 and 2500.

[0103] Optionally, as contemplated above, the additional particles may be incorporated into at least one of the metallization solutions projected onto the substrate during metallization step D. The additional particles are thus advantageously trapped in the metal deposit formed on the substrate surface.

[0104] As mentioned above in this specification, such a metallization method by spraying an aerosol(s) is particularly interesting in that it allows a simple and rapid metallization of substrates of any size, especially of large size, and is particularly well suited in cases where the metallization step D is carried out after a thermoforming step C (variant V1) and therefore the surface to be metallized is not flat but deformed.

[0105] Moreover, such a method of metallization by spraying aerosol(s) makes it possible, in the context of the present invention, to obtain a metal deposit, possibly multi-layered, with excellent properties, in particular with regard to adhesion to the substrate, thickness uniformity and surface condition (very low roughness). It is therefore advantageously possible in this way to obtain one or more metal patterns, in particular with excellent properties in terms of electrical conductivity. Moreover, such a method of metallization by spraying aerosol(s) makes it possible to particularly finely control the thickness of the metal deposit formed, which can therefore be made particularly transparent or opaque depending on the application. -Electroless deposition by immersion

[0106] According to what has been explained above, in embodiments in which the metallization of the substrate is carried out by autocatalytic (or "electroless") chemical deposition by immersing the substrate in one or more metallization solutions, a step H of activating the substrate can advantageously be carried out before the metallization step D, and optionally before said activation step H at least one of the following steps can be carried out, preferably in the following order: a satin finishing step S, preferably implemented between the step B of forming the temporary masking coating and the activation step H; When implementing such a satin finish step S, a step T is performed of rinsing the substrate surface.

[0107] Advantageously, the satin finishing step S is a treatment step for increasing the surface energy of the substrate as described above for electroless metallization by spraying with an aerosol (step P). The same applies to the rinsing step T.

[0108] As introduced above, the metallization step D, in this particular embodiment, is typically carried out by immersing the substrate in a bath of metallization solution (a "non-electrolytic" bath) that contains, in addition to one or more metal cations and one or more reducing agents, optionally one or more complexing agents, one or more stabilizing agents, and any other additives (such as surfactants). Typically, in step D, a metal deposit is formed on all areas of the substrate on which a catalyst was previously deposited during the activation step H.

[0109] As long as the activation step H is preferentially carried out after the step B of forming the temporary masking coating and before the step E of removing the temporary masking coating, the substrate area(s) covered with the temporary masking coating will therefore not be catalyzed and therefore cannot be a metal deposit formation site.

[0110] Preferably, the metallization step D is here carried out after the step E of removing the temporary masking coating. Indeed, on the contrary, in the hypothesis that the metallization step D is carried out before step E, it would be advantageous to provide that the temporary masking coating is designed so that the catalyst cannot be adsorbed on the surface of the catalyst, said temporary masking coating being adapted to resist said "non-electrolytic" bath, in order to limit the risk of contamination of said "non-electrolytic" bath. -Electrodeposition

[0111] For more details on this metallization method, which may possibly be implemented in a metallization step D, reference can be made to technical literature relating to this technology, for example galvanostage papers. -Step E- Removing the temporary masking coating

[0112] In accordance with the above, step E is In particular, if the method comprises a step H of activating the substrate surface before the metallization step D, and the temporary masking coating is intended to allow selective activation of the substrate surface, then (total) before the metallization step D: or (in total) after step D, Or, more preferentially, it can be performed either during the metallization step D (in its entirety), or partly during step D and partly after step D, or partly before step D, partly during step D and partly after step D.

[0113] As introduced above, step E advantageously comprises or consists essentially of at least one dissolving operation of the temporary masking coating by at least one solvent implemented in the method.

[0114] In the hypothesis that the method comprises a step I of rinsing the surface of the metallized substrate, the step E of removing the temporary protection can potentially be performed during the rinsing step I or partially during the metallization step D and at least partially during said rinsing step I. In the hypothesis that the method comprises a drying step J, the step E of removing the temporary protection can potentially be performed partially during the metallization step D and at least partially during said drying step J.

[0115] The operation of dissolving the temporary masking coating can be carried out, for example, by spraying with one (or more) aqueous solvents, by spraying with one (or more) organic solvents, by spraying a mixture of aqueous solvent(s) and organic solvent(s), by immersion in a bath of aqueous solvent(s), by immersion in a bath of organic solvent(s) or by immersion in a bath of a mixture of aqueous solvent(s) and organic solvent(s). Potentially, said dissolving operation can be carried out with a heat input and therefore at a temperature preferentially between 30°C and 90°C, more preferentially between 50°C and 80°C. In practice, the time during which step E is carried out can depend in particular on how the metallization step D is carried out and in particular on the metallization method(s) implemented during the latter. In particular, the removal of the temporary masking coating at least partially during the metallization step D assumes that the method by which the latter is carried out allows this removal and that the residues generated by this removal are not of a nature that would hinder the smooth execution of the metallization step D. -electroless deposition by projection in the form of aerosol(s)

[0116] In this embodiment, step E of removing the temporary masking coating can be carried out at least partially during step D in the advantageous cases described above, in which a solvent adapted to dissolve the temporary masking coating is contained in the metallization solution or at least one of the metallization solutions used during step D.

[0117] In practice, even more preferably, the temporary masking coating is alkali soluble (or at least alkali sensitive) and the metallization solution (or one of the metallization solutions) has a highly alkaline pH (typically higher than 9) so that the metallization solution(s) are able to dissolve the temporary masking coating during step D. Typically, during spraying of the metallization solution in the form of the aerosol(s), the unmasked areas of the substrate are metallized, while the temporary masking coating is dissolved and expelled by the effluent, thus resulting in either: If step D is performed after the thermoforming step C (variant V1), the desired metal pattern, Or, if step D is performed before the thermoforming step C (variant V2), one (or more) corresponding "green" metal pattern(s), as described above.

[0118] However, the duration of the metallization, i.e. the time required to form the metal deposit in step D, is preferably limited so as to prevent risk of metallization of substrate areas initially covered with the temporary masking coating.

[0119] In this embodiment of spraying the aerosol(s), as a complement or alternative, it is possible to rinse the masked metallized surface of the substrate, for example by spraying, with one or more solvents adapted to dissolve the temporary masking coating, especially if the metallization solution(s) used do not contain a solvent adapted to dissolve the temporary masking coating. The dissolution of the temporary masking coating is thus accompanied by the expulsion of any metal deposits present on its surface. -Electroless deposition by immersion

[0120] In this other embodiment, which generally includes implementing the activation step H described above, step E can be typically performed between step H and metallization step D by applying to the surface of the masked substrate a solvent adapted to dissolve the temporary masking coating. Such application can be performed, for example, by immersing the masked substrate in said solvent or by spraying the masked substrate surface with said solvent followed by a rinsing operation.

[0121] This dissolution reveals activated area(s) of the substrate surface that can receive metal deposits intended to form the desired metal pattern(s). Conversely, the area(s) of the substrate surface that was previously covered with the temporary masking coating is not activated (adsorption of catalyst) in step H, and as a result, no metal deposits are formed thereon, at least for the duration required for the formation of metal deposits on the activated area(s) of the substrate surface. -Electrodeposition

[0122] In this embodiment, a step E of removing the temporary masking coating can possibly be carried out at least partially during the metallization step D, typically when the metallization solution used comprises a solvent adapted to dissolve the temporary masking coating and the time required for the formation of the metal deposit by electrolytic deposition is advantageously equal to or less than the time required for the dissolution of the temporary masking coating by said solvent. Alternatively, or possibly as a complement, step E can be carried out after the metallization step D, for example during a step I of rinsing the produced metallized substrate using a rinsing liquid comprising or forming a solvent adapted to dissolve the temporary masking coating. -Step I: Rinse the metallized substrate surface-

[0123] After the metallization step D, the method may comprise a step I of rinsing the metallized surface of the substrate, as described above. The rinsing step I, like the other rinsing step(s) in the method (in particular steps P and R), may be carried out by any known suitable method, for example by spraying / projecting one or more rinsing liquids using an HVLP gun, or by immersion / dipping in one or more rinsing liquids. The latter is preferably water, more preferably demineralized water, except in some cases where the rinsing liquid contains or forms a solvent (other than water) for dissolving the temporary masking coating. - Step J of drying the metallized substrate surface -

[0124] After step I of rinsing the metallized substrate surface, the method can include step J of drying the metallized substrate surface. Drying step J consists of draining the rinsing liquid, as a potential further drying step that can occur after each rinsing step. Such drying can typically be carried out at ambient temperature by blowing a compressed air stream, for example at a pressure of 5 bar, or using an air knife type blowing system. It can also be dried in open air or in an oven. -Steps K, L, M of finishing the metallized substrate surface-

[0125] For example, in order to protect the metal pattern(s) formed from the metal deposit from external physical and / or chemical attack and / or to modify or improve the properties of the metal pattern(s), e.g. with respect to electrical conductivity and / or optical properties, one(s) complementary "finishing" step(s) can be implemented after the metallization step D, and more preferably after the thermoforming step C, if the latter is performed after the metallization step D.

[0126] Thus, the method may possibly include a complementary metallization step K (or "thickening step") by forming at least one additional metal deposit on the surface of the (initial) metal deposit obtained at the end of the metallization step D. Such a complementary metallization step K may advantageously be carried out by electrolytic deposition (for example galvanostatic) or by electroless deposition ("non-electrolytic"). Said additional metal deposit may or may not have the same composition as the initial metal deposit. For example, the additional metal deposit may comprise or be formed from at least one metal selected from among silver, nickel, copper, gold, iron, cobalt, tin, zinc, ruthenium, palladium, one or more oxides of these latter, or one or more alloys of these latter, or combinations thereof. Such a complementary metallization step K may be interesting in particular when the (initial) metallization step D is carried out by electroless chemical deposition as contemplated above and it is desired to obtain one (or more) metal patterns with a total thickness of more than 5 μm.

[0127] Alternatively or supplementarily, the method may optionally comprise a step L of passivating the metal deposit(s) forming the metal pattern(s) in order to protect the metal pattern(s) against corrosion or oxidation. Typically, such a passivation step L is carried out using at least one passivation solution adapted to the composition of the metal deposit(s) forming the metal pattern(s), for example a solution of inorganic tin salt(s), a commercially available organic noble metal passivation solution, or a silane or silicon oxide (SiO x This can be carried out by spraying or immersion with inorganic solutions from the family of

[0128] Alternatively or supplementary, the method may optionally comprise, after the above-mentioned metallization step D and thermoforming step C, and preferably after the step E of removing the temporary masking coating, a step M of forming a covering finish coating on the substrate surface carrying the metal pattern(s) (metallized thermoformed substrate). Such an organic or inorganic finish coating may constitute a protective coating against mechanical abrasion, oxidation, etc., and / or an electrically insulating coating, and / or a decorative coating. The step M of forming a finish coating may typically be carried out by depositing / applying, by any known suitable technique, at least one finish layer of a curable and / or crosslinkable liquid composition (for example by exposure to UV or thermal curing) on ​​the substrate surface carrying the metal pattern(s). The liquid composition may for example be a paint or varnish, advantageously chosen from the group of alkyds, polyurethanes, epoxies, vinyls, acrylics and mixtures thereof. Preferably, the liquid composition is a varnish, potentially pigmented / pigmented, advantageously chosen from the following compositions: epoxies, alkyds and acrylics. -Overmolding Step N-

[0129] Optionally, the method according to the invention may comprise, after the thermoforming step C, a step N of overmolding the (thermoformed) substrate. Step N may be carried out after the metallization step D, if it is carried out after the thermoforming step C, or on the contrary before the metallization step D, under the hypothesis that there is a risk that the metal deposit / pattern(s) will be damaged during the overmolding step N. The overmolding (or injection molding) step N advantageously consists in injecting a polymer material or a mixture of polymer materials that is compatible with the material properties of the thermoformed substrate into a mold inside which the previously thermoformed (and preferentially metallized) substrate is placed. Such an overmolding step advantageously makes it possible, for example, to form a protective and / or supporting part for the thermoformed (and preferentially metallized) substrate. -Step O of Assembling Additional Components-

[0130] In certain applications of three-dimensional articles, it may be desirable to assemble, through and / or on the surface of the thermoformed substrate with overmolded or non-overmolded metal pattern(s), one(s) electric, electronic and / or optoelectronic component(s) (electrical connector(s), electric cable(s) / wire(s), light emitting diode(s), electronic chip(s), etc.). Advantageously, such an assembly step O can be implemented using one or more robotized surface mounted component (SMD) placement systems, commonly known as "pick and place" or "P&P" machines, one or more robotized arms, or any other known and advantageously automated means for depositing liquids / components on a 2.5D or 3D surface. Such an assembly step can advantageously be performed by soldering and / or using an isotropic or anisotropic conductive adhesive, for example in the form of a film or paste and of any suitable chemistry (silicone, epoxy, acrylic, etc.). The conductive adhesive can be cured as required.

[0131] Finally, the method according to the invention has the following advantages in particular: It allows the production of three-dimensional articles of any size and complex shape, equipped with decorative / functional metal pattern(s), which themselves can be of large size and / or complex shape. It makes it possible to produce three-dimensional articles with metal pattern(s), which may be particularly fine, precise and / or intricate. It makes it possible to produce three-dimensional articles with a metal pattern(s) that are particularly resistant to external attack. It makes it possible to produce three-dimensional articles with metal pattern(s) which are uniform and regular in pattern both in terms of thickness and surface aspect (very low roughness). It allows the production of three-dimensional articles with metallic patterns in a wide range of possible materials (pure metals, metal alloys, metal oxides, etc.). It makes it possible to manufacture three-dimensional articles with metal pattern(s) that can be used in a wide range of technical applications, including some of the most demanding and agile in terms of metal pattern properties (thinness, thickness, purity, conductivity, roughness, etc.), said metal pattern(s) may be decorative and / or functional and thus advantageously form or contribute to the formation of, for example but not limited to, one or more printed circuits, one or more integrated circuits on a semiconductive substrate, one or more sensor / detector electrodes, one or more electrodes of an electric heater / defroster, one or more radio frequency antenna radiating elements (WiFi, RFID, etc.), one or more coded pictograms that can be read by electronic equipment, one or more graphic and / or textual information items that identify a product incorporated or associated with said three-dimensional article, in particular a commercial product, such as visual or decorative designs on packaging, on automotive products. It can be used in industrial situations for mass production. It is particularly quick, easy and economical to implement.

[0132] Two examples of implementations of the method according to the invention for manufacturing a three-dimensional article with metal pattern(s) will now be described with reference to the accompanying drawings: Example 1 shows in particular the implementation of variant V1, in which the thermoforming step C is performed before the metallization step D, and Example 2 shows in particular the implementation of variant V2, in which the thermoforming step C is performed after the metallization step D.

[0133] -Example 1: Manufacturing of a three-dimensional RFID antenna- - Step A: A flat substrate made of a polycarbonate film with a thickness of 250 μm and a size of 330 mm long x 250 mm wide is prepared. - Step B: A temporary masking coating is formed by screen printing on a polycarbonate film from a thermoformable and alkali-sensitive masking composition developed by JET METAL TECHNOLOGIES®. The deposited layer of masking composition is then dried by desolvation at 60° C. for 5 minutes. The so-formed temporary masking coating defines at least one unmasked area (in the center), as shown by way of example in FIG. 1. - Step C: The film so selectively masked is then uniformly heated by infrared (IR) up to 215°C and then applied against an inverse shape for thermoforming. Figure 2 shows an example of a thermoformed mask film obtained after cooling and hardening. - Step P / Step Q: The surface of the thermoformed mask film is subjected to a treatment to increase the surface energy by plasma treatment (so-called "air" plasma: 80% nitrogen / 20% oxygen for 2 minutes at 0.5 mbar (i.e. 50 Pa)), so that at the end of this treatment the surface energy of the thermoformed mask film is higher than 50 dynes and said surface can be completely wetted by water projection, water, then a continuous film is formed on the surface of the thermoformed mask film. - Step H: A stannous chloride based sensitizing solution is projected onto the surface of the thermoformed mask film using an HVLP gun for 10 seconds. - Step R: Rinse the surface of the thermoformed mask film by spraying with demineralized water using an HVLP gun for 10 seconds to drain off the sensitizing solution. - Step D / Step E: A metal deposit is formed on the surface of the thermoformed mask film by simultaneous spraying of a first aqueous metallization solution (oxidizing solution) based on silver nitrate in a concentration of 2 g / l and having a pH>9, and a second metallization solution (reducing solution) based on glucose, at 2.5 bar (i.e. 2.5.10 5The substrate is exposed for 80 seconds by an HVLP gun set at a spray pressure of less than 100 Pa. Under the influence of the alkalinity of the first metallization solution, the alkali-sensitive temporary masking coating is partially decomposed and expelled from the substrate surface with the effluent, thus revealing the desired metallization pattern. - Step I: The surface of the metallized thermoformed film is rinsed with water by an HVLP gun. This rinsing makes it possible to expel any potential residues of the temporary masking coating. In some cases, a complementary rinsing can be carried out by immersion in a bath or by spraying with a solution containing a solvent of the ethanol / isopropanol type, ensuring the complete absence of residues of the temporary masking coating and the metal deposits carried by these. - Step J: The surface of the metallized thermoformed film is exposed to an air flow of 5 bar (i.e., 5.10 5 The film is then dried at ambient temperature under 100 MPa (100 psi) for 20 min. The results are shown in Figure 3, where the thermoformed polycarbonate film and the resulting metallic pattern of solid elemental silver on its surface form a three-dimensional RFID antenna. - Step O: An electronic RFID antenna chip is then assembled onto the metallized thermoformed film by soldering or using a conductive adhesive. - Step M: The metallized surface of the three-dimensional object thus obtained is then coated using a protective varnish developed by JET METAL TECHNOLOGIES®.

[0134] Example 2 - Production of a three-dimensional object containing a decorative pattern in the form of silver wires - Step A: A flat substrate made of a polycarbonate film with a thickness of 250 μm and a size of 380 mm long x 310 mm wide is prepared. - Step B: A temporary masking coating is formed by screen printing on a polycarbonate film from an alkali-sensitive masking composition developed by JET METAL TECHNOLOGIES®. The deposited layer of masking composition is then dried by desolvation at 80° C. for 5 minutes. The so-formed temporary masking coating defines a plurality of unmasked areas in the form of lines, as shown by way of example in FIG. 4. - Step P / Step Q: The surface of the mask film is subjected to a treatment to increase the surface energy by direct ceramic corona treatment at a speed of 3 m / min and 3 passes, so that at the end of this treatment, the surface energy of the mask film is higher than 50 dynes, and said surface can be completely wetted by water projection, water then forms a continuous film on the surface of the mask film. - Step H: A stannous chloride based sensitizing solution is projected onto the surface of the mask film using an HVLP gun for 10 seconds. - Step R: Rinse the surface of the mask film by spraying with demineralized water using an HVLP gun for 10 seconds and draining the sensitizing solution. - Step D / Step E: A metal deposit is formed on the surface of the mask film, which is sensitized for 80 seconds by an HVLP gun by simultaneous spraying of a first aqueous metallization solution (oxidizing solution) based on silver nitrate at a concentration of 2 g / l and having a pH>9, and a second metallization solution (reducing solution) based on glucose. Under the influence of the alkalinity of the first metallization solution, the alkali-sensitive temporary masking coating is partially decomposed and is expelled from the substrate surface together with the effluent. - Step I: The surface of the metallized film is then successively rinsed with water using an HVLP for 10 seconds, then rinsed with the rinsing solution "Select Rinse" developed by JET METAL TECHNOLOGIES® using an HVLP gun for 15 seconds in order to remove any residues of the temporary masking coating, then rinsed again with water using an HVLP gun. - Step J: The surface of the metallized film is exposed to an air flow of 5 bar (i.e., 5.10 5 The resulting metallized film is then dried at ambient temperature under 1000 MPa (100 psi). FIG. 5 shows by way of example the metallized film thus obtained. - Step C: The film so selectively masked is then uniformly heated by infrared (IR) up to 215°C and then applied against an inverse shape for thermoforming. Figure 6 shows, by way of example, the thermoformed mask film so obtained after cooling and hardening, which can then be formed by itself or used to form a three-dimensional article. [Industrial Applicability]

[0135] The present invention finds application in the general technical field of three-dimensional articles having decorative and / or functional metallic pattern(s) and methods for producing such articles.

Claims

1. 1. A method for manufacturing a three-dimensional article comprising at least one metal pattern, comprising: Step A: providing a flat substrate of thermoforming material; Step B of forming a temporary masking coating on a surface of the flat substrate, the temporary masking coating adhering to the surface, to obtain a masked substrate having at least one unmasked area; C. thermoforming the flat substrate to impart a substantially three-dimensional shape to the flat substrate; D. metallizing the masked substrate to form a metal deposit on the masked substrate, at least on the unmasked areas; Step E of removing the temporary masking coating; At least said thermoforming step C being carried out before a metallization step D and before a step E of removing said temporary masking coating; A method in which the metallization step D is carried out by electroless deposition from one or more metallization solutions comprising at least one metal in the form of a metal cation and at least one reducing agent adapted to convert said metal cation into a metal by spraying the metallization solution in the form of one or more aerosols.

2. The method of claim 1 , wherein the metal deposit is made of a solid metal.

3. The method according to claims 1 and 2, wherein the metal deposit has a thickness at the end of the metallization step D between 10 nm and 5 μm, preferably between 10 nm and 1 μm, and even more preferably between 10 nm and 500 nm.

4. 4. The method of claim 1, wherein step D is performed such that a thickness of the metal deposit is variable over a range of the metal deposit, the metal deposit having at least a first region and a second region that are different from one another, and the thickness of the metal deposit increases or decreases from the first region to the second region.

5. 5. The method according to claim 1, wherein a step E of removing the temporary masking coating is performed during a metallization step D, or partially during and partially after a metallization step D, or partially before, partially during and partially after a metallization step D.

6. 6. The method according to any one of claims 1 to 5, wherein step E of removing the temporary masking coating comprises at least one operation of dissolving the temporary masking coating using at least one solvent implemented in the method, the temporary masking coating being preferably alkali-soluble so that it can be preferentially dissolved by an alkaline solvent implemented in the method.

7. The method according to claims 5 and 6, wherein the solvent is contained in the metallization solution or one of the metallization solutions.

8. 8. The method according to claim 1, wherein step B of forming the temporary masking coating is carried out by selectively depositing, e.g. by screen printing and / or direct printing, a layer of a liquid or pasty masking composition on the flat substrate surface and optionally drying and / or curing the layer of masking composition.

9. 9. The method according to any one of claims 1 to 8, wherein the temporary masking coating has, at the end of its forming step, a thickness between 100 nm and 50 μm, preferably between 500 nm and 20 μm, more preferably between 1 μm and 10 μm.

10. 10. The method according to any one of claims 1 to 9, wherein said flat substrate is a film, sheet or plate of a thermoforming polymer material or a composite polymer matrix thermoforming material, preferentially with a thickness of between 8 μm and 15 mm, more preferably between 25 μm and 10 mm.

11. 11. The method according to claim 1, further comprising a step G of modelling the deformation of the flat substrate in the thermoforming step C and representing the resulting metal pattern, thereby defining a two-dimensional masking pattern on the flat substrate surface on which the temporary masking coating is subsequently formed.

12. 12. The method according to claim 1, further comprising, after the thermoforming step C, a step N of overmolding the substrate.

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