Method for manufacturing a timepiece component

Abstract

The invention relates to a method for manufacturing a watch component comprising the following steps: a. obtaining a support made of polymer material; b. forming at least one base layer on at least a part of the support, said at least one base layer being based on a metallic material whose equilibrium constant with respect to cyanide ions is greater than or equal to 10; c. forming at least one main layer on said at least one base layer by electroplating using a galvanic bath not containing cyanide ions in order to form a watch component; d. separating the watch component from the support by immersing them in a solution containing cyanide ions so that the bonds of said at least one base layer with the support recombine with the cyanide ions.

Description

TECHNICAL FIELD OF THE INVENTION

[0001] The present invention relates to a method of manufacturing a watch component using electroforming (galvanic growth on a support) followed by a separation step between the support and the galvanic deposit to form the watch component. TECHNICAL BACKGROUND OF THE INVENTION

[0002] Electroforming is increasingly used in various sectors such as watchmaking. It consists of galvanic growth (electroplating) in a mold (for example obtained by photolithography (LiGA process)). Thus, electroforming can be used for mass replication processes. These technologies generally use a mold (for example a substrate or a mandrel) made of polymer material on which electroforming takes place.

[0003] An electroforming process is generally used on molds for double-sided metal growth. A first step of thin metal deposition is therefore carried out on a polymer mold in order to coat the mold, then a second step of thick metal deposition by electroplating against the thin metal deposit. Finally, a final step consists of separating the metal deposit from the mold to obtain the watch component.

[0004] However, in watchmaking, growths are generally desired on one side only. This means that the polymer material mold can interact with the electrolytics of the galvanic bath. In addition, the known steps of mold removal by chemical dissolution or mechanical demolding are not satisfactory. Chemical dissolution is generally slow, which makes the process unproductive and uses expensive solvents that can alter the galvanic deposit and are dangerous for operators. Finally, mechanical demolding is complex (preliminary phase of mold preparation followed by a thermal shock (or mechanical shock) phase), which makes the process unproductive and can damage the watch component (or leave pieces of the mold on the watch component), resulting in a significant scrap rate. SUMMARY OF THE INVENTION

[0005] The aim of the invention is to propose a method for manufacturing a metallic watch component using electroforming using a polymer material support followed by a step of removing the metallic deposit from the polymer material support which is improved both in terms of selective separation

[0006] (obtaining a watch component faithful to the geometry of the electroforming support, i.e. without breaking the galvanic deposit or agglomeration of a material of the support) as well as shortening the removal step (rapid separation step without using new chemical means which are not already present elsewhere in watchmaking production by electroplating).

[0007] To this end, the invention relates to a method for manufacturing a watch component comprising the following steps: a. providing a support made of polymer material; b. forming at least one base layer on at least part of the support, said at least one base layer being based on a metallic material whose equilibrium constant with respect to cyanide ions is greater than or equal to 10; c. forming at least one main layer on said at least one base layer by electroplating using a galvanic bath not comprising cyanide ions in order to form a watch component; d. separating the watch component from the support by immersing them in a solution comprising cyanide ions so that the bonds of said at least one base layer with the support recombine with the cyanide ions.

[0008] Conventionally, a layer of a precious metal, such as pure gold, can be deposited by physical vapor deposition (sometimes known by the abbreviation PVD) on a polymer support to support a subsequent electroforming step. In fact, precious metals such as pure gold are preferentially deposited on polymer supports because they are very stable, particularly due to their resistance to different environments: acid, basic, chlorinated, no oxidation in ambient air, and possible galvanic recovery.

[0009] Following the delaminations of galvanic deposits observed, particularly in the case of cyanide electrolytes in galvanic baths used to obtain an 18-carat gold deposit, the source of the chemical incompatibility between the cyanide electrolyte and the materials used was investigated.

[0010] Compatibility has been found to be based on the nature of the metal-polymer support interactions. These are weak physisorption bonds that can be easily cleaved in the presence of a complexing agent with strong affinities for the metal. This strong affinity can be characterized by an equilibrium constant pKf, equivalent to the value of -log(Kf), Kf being the formation constant. The higher its value, the higher the stability of the complex and the higher the metal-ligand affinity.

[0011] The invention advantageously uses this observation to, on the one hand, form said at least one main layer on said at least one base layer by electroplating using a galvanic bath not comprising cyanide ions in order to avoid any delamination and then, on the other hand, to choose a strong metal - cyanide ion affinity of said at least one base layer to separate, thanks to its strong affinity, the watch component from the support by immersing them in a solution comprising cyanide ions.

[0012] The pure gold deposit can therefore continue to be used to form said at least one base layer. Indeed, such a gold layer forms an effective layer to serve as a seat for electroplating during step c. In addition, its affinity is very strong with cyanide ions. Thus, it has been calculated that the equilibrium constant pKf is located between 38.3 and 15.27 depending on the cyanide derivative present in the solution used in step d. During the latter, there is therefore an exchange between the cyanide ions and said at least one base layer which will induce a cleavage of the metal-polymer support bonds and incidentally cause the delamination of the watch component relative to the support.

[0013] It is understood that the watch component is released from the support in a very selective manner and that the support and watch component do not undergo any shock (thermal, mechanical or chemical) likely to damage them. In addition, step d can be obtained using a cyanide galvanic bath already present in the manufacturing workshop but without having to impose a potential difference. Only the free cyanides in the galvanic bath will interact with said at least one base layer. The face of the watch component that was against the support therefore remains very faithful to the geometry of the electroforming support and no particle of a material of the support remains on the watch component. Finally, the strong affinity of said at least one base layer with the cyanide ions allows a rapid removal step d typically between 1 minute and 50 minutes.Therefore, in view of the above, the method, advantageously according to the invention, can boast a much lower production cost while making it possible to obtain high-quality watch components.

[0014] The invention may also include one or more of the following optional features, taken alone or in combination.

[0015] Step a may comprise the phases i intended to provide a replication tool comprising in part a geometry to be reproduced of the watch component, ii intended to at least partially cover the replication tool with a polymer material in order to form a support made of polymer material with a geometry complementary to the geometry to be reproduced of the watch component and iii intended to release the support made of polymer material from the replication tool.

[0016] Of course, step a could be different, such as forming the support in polymer material without using a replication tool and / or from an injection mold. The support could also be obtained from a flat substrate in a first polymer material covered with an openwork mask (obtained for example from photolithography) in a second polymer material. It is understood that the openworks, each bottom of which is formed by the flat substrate, could serve as molds for galvanic growth and whose wall shape makes it possible to obtain a three-dimensional watch component of predetermined geometry.

[0017] Preferably, said at least one base layer is based on a metallic material whose equilibrium constant with respect to cyanide ions is greater than or equal to 15. Such a metallic material may be based on gold and / or silver and / or platinum. It is therefore understood that each metallic material may be pure or in the form of the main element of an alloy of at least one other metallic material from the list and / or at least one other element not belonging to the list.

[0018] Step b is preferably obtained by physical vapor deposition. Of course, other deposition methods can be envisaged without departing from the scope of the invention.

[0019] In step c, the galvanic bath not containing cyanide ions can be used to deposit a material based on copper and / or silver and / or gold and / or nickel and / or chromium and / or zinc and / or bronze. Of course, other types of deposition can be envisaged without departing from the scope of the invention as long as the galvanic bath does not contain cyanide ions.

[0020] In step d, the solution containing cyanide ions may have a cyanide ion concentration of at least 5 gl -1< in order to obtain sufficiently rapid delamination. Typically, the concentration is preferably between 5 gl -1< and 15 gl -1< , that is to say can, for example, be equal to 5 gl -1< , 6 gl -1< , 7 gl -1< , 8 gl -1< , 9 gl -1< , 10 gl -1< , 11 gl -1< , 12 gl -1< , 13 gl -1< , 14 gl -1< , 15 gl -1< , 16 gl -1< , 17 gl -1< , 18 gl -1< , 19 gl -1< , 20 gl -1< , 21 gl -1< , 22 gl -1< , 23 gl -1< , 24 gl -1< , 25 gl -1< , 26 gl -1< , 27 gl -1< , 28 gl -1< , 29 gl -1< , 30 gl -1< , 31 gl -1< , 32 gl -1< , 33 gl -1< , 34 gl -1< or 35 gl -1< . The higher the concentration, the shorter the delamination step d. The process is diffusion limited so care must be taken not to over-concentrate the solution to increase the viscosity too much. The preferred concentration is between 12 g.l -1< and 22 gl -1< .

[0021] In order to further shorten the duration of step d, agitation of the solution may be implemented in order to force the movement of the solution around the support and the watch component. Typically, if a cyanide galvanic bath is used for step d, the agitation element of the galvanic bath is activated.

[0022] In step d, the solution may have a temperature between 30°C and 60°C, i.e. may, for example, be 30°C, 31°C, 32°C, 33°C, 34°C, 35°C, 36°C, 37°C, 38°C, 39°C, 40°C, 41°C, 42°C, 43°C, 44°C, 45°C, 46°C, 47°C, 48°C, 49°C, 50°C, 51°C, 52°C, 53°C, 54°C, 55°C, 56°C, 57°C, 58°C, 59°C or 60°C. Temperature is a factor that promotes diffusion. In a particular embodiment, the temperature is 45°C.

[0023] Finally, in step d, the solution may have a basic pH of between 10 and 15, i.e. may, for example, be equal to 10, 10.5, 11, 11.5, 12, 12.5, 13, 13.5, 14, 14.5 or 15. Indeed, the basic pH of between 10 and 15 promotes demolding and makes the process safer by avoiding the risk of release of hydrocyanic acid. In a particular embodiment, the pH is between 13 and 14.

[0024] After step c and before step d, the method may include a step α (alpha) intended to machine the watch component in order to modify its shape by removing material. Advantageously according to the invention, it is thus possible to work and / or decorate and / or remove any surplus of said at least one main layer while the support made of polymer material is still integral with said at least one base layer. Step α (alpha) may, for example, make it possible to form at least one fixing element of the watch component. By way of non-limiting example, step α (alpha) could, for example, form feet of the watch component forming a watch dial in order to fix the latter to a watch movement.

[0025] After step d, the method may comprise a step e (which may be a final step) intended to form at least one decorative layer on at least part of the watch component in order to modify the aesthetic appearance of the watch component. Typically, this makes it possible to form said at least one main layer based on a less noble metallic material such as pure copper (or one of its alloys) and then to cover (for example by another electroplating) all or part of said at least one main layer with at least one decorative layer made of a more noble material such as based on a precious metal such as pure gold (or one of its alloys) in order to give a more high-end finish to the watch component. Of course, step e may be obtained by another type of deposition such as, for example, physical vapor deposition, chemical vapor deposition or autocatalytic deposition. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Other features and advantages of the invention will emerge clearly from the description given below, for information purposes only and in no way limiting, with reference to the appended drawings, in which: there figure 1 is a schematic view of an example of a timepiece; the figures 2 to 6 are schematic views of successive steps of an example of a first embodiment of a method according to the invention; the figures 7 to 9 are schematic views of successive steps of an example of a second embodiment of a method according to the invention; figure 10 is a diagram representing an example of a method according to the invention. DETAILED DESCRIPTION OF AT LEAST ONE EMBODIMENT OF THE INVENTION

[0027] In the various figures, identical or similar elements bear the same references, possibly with the addition of an index. The description of their structure and function is therefore not systematically repeated.

[0028] In all that follows, the orientations are the orientations of the figures. In particular, the terms "upper", "lower", "left", "right", "above", "below", "forward" and "backward" are generally understood in relation to the direction in which the figures are represented.

[0029] By "polymer" is meant all materials formed from at least one polymer chain, sometimes called fiber, more or less long which can be of natural or synthetic origin. In the context of the invention, the term polymer can therefore refer to a resin (in particular photosensitive such as SU-8) or an organic varnish. In the context of the invention, by way of non-limiting example, a polymer material can comprise, for example, polycarbonate (PC) and / or polymethyl methacrylate (PMMA, sometimes called plexiglass) and / or cycloolefin copolymer (COC) and / or acrylonitrile butadiene styrene (ABS) and / or methyl methacrylate acrylonitrile butadiene styrene (mABS).

[0030] "Based on" means a material or alloy constituting at least 50% by total mass or weight of a given element. By way of example but not limitation, a gold-based material means a material formed from pure gold (24 carat gold) or a material formed by alloying gold with at least one other element, the gold constituting at least 50% by total mass or weight of the material.

[0031] In the following, unless otherwise indicated, all percentages (%) indicated are percentages by total mass or weight.

[0032] By "pure metal" is meant a material theoretically formed at 100% by total mass or weight of a given metal, i.e. without any other alloying metal. In practice, depending on the manufacturing process, the material obtained may include so-called polluting elements whose proportion by weight does not exceed 0.2% of the total mass of the alloy which generally prevents obtaining 100% of metal by total mass but rather substantially between 97% and 100%.

[0033] By "thin deposit" is meant a thickness of deposited material of at most 1000 nm such as said at least one base layer 11 for example implemented by step b of the method according to the invention. Preferably, the thin deposit can also be at least 1 nm. The thin deposit may thus comprise a thickness of deposited material equal to 1 nm, 5 nm, 10 nm, 20 nm, 30 nm, 40 nm, 50 nm, 60 nm, 70 nm, 80 nm, 90 nm, 100 nm, 150 nm, 200 nm, 250 nm, 300 nm, 350 nm, 400 nm, 450 nm, 500 nm, 550 nm, 600 nm, 650 nm, 700 nm, 750 nm, 800 nm, 850 nm, 900 nm or 1000 nm. The purpose of this thin deposit is to provide a compatible layer to serve as a seat for the future electroplating (step c) because the support 10 made of polymer material does not allow it.

[0034] By "thick deposit" is meant a thickness of deposited material of at least 2 µm such as said at least one main layer 12 for example implemented by step c of the method according to the invention. Preferably, the thick deposit can also be at most 1000 µm. The very thick deposit can thus include a thickness of deposited material equal to 2 µm, 5 µm, 10 µm, 20 µm, 30 µm, 40 µm, 50 µm, 60 µm, 70 µm, 80 µm, 90 µm, 100 µm, 150 µm, 200 µm, 250 µm, 300 µm, 350 µm, 400 µm, 450 µm, 500 µm, 550 µm, 600 µm, 650 µm, 700 µm, 750 µm, 800 µm, 850 µm, 900 µm or 1000 µm. The purpose of this thick deposit (compared to each of the thin deposits) is to provide a mechanically robust layer to serve as the main metal part (solid metal part). Preferably, the thick deposit has a thickness of deposited material at least equal to 200 µm.

[0035] By "timepiece" we mean all types of instruments for measuring or counting time such as clocks, small clocks, watches, etc.

[0036] By "watch movement" we mean all types of mechanism capable of counting time, whether powered by mechanical energy (for example a barrel) or electrical energy (for example a battery).

[0037] By "dressing" we mean all types of devices capable of containing, displaying, decorating and / or controlling a watch movement such as, for example, all or part of a case, a bracelet or a display.

[0038] By "micromechanical part" we mean all types of parts that can be used in a watch, particularly to form its watch movement.

[0039] The method according to the invention is intended to manufacture a component 1 in the watchmaking field which is in particular intended to be mounted in a timepiece 2. Thus, the component 1 can form all or part of a watch casing such as all or part of a dial (as illustrated in figure 1 ) or a flange, a display such as a hand or a disc, a case, a bracelet, a crystal or a control organ such as a crown or a push button. Component 1 may also form all or part of a watch movement 3 such as a micromechanical part such as all or part of an escapement device such as a Swiss anchor mechanism, a resonator such as a balance-spring mechanism, an energy source such as a barrel, an automatic winding system or a battery, a gear train such as a mobile or a toothed wheel, a spring, a screw, a bridge or a plate.

[0040] As will be explained in more detail below, the method according to the invention allows the manufacture of a component 1 formed from a single metal (or alloy) or from several metallic materials.

[0041] The invention aims to propose a method for manufacturing a metallic watch component 1 using electroforming using a support 10 made of polymer material followed by a step of removing the metallic deposit 11, 12 from the support 10 made of polymer material which is improved both in terms of selective separation (obtaining a watch component 1 faithful to the geometry of the electroforming support 10, i.e. without breaking the galvanic deposit 12 or agglomeration of a material of the support 10) and shortening the removal step (rapid separation step without using new chemical means which are not already present elsewhere in watchmaking manufacturing by electroplating).

[0042] Conventionally, a layer of pure gold is deposited by physical vapor deposition on a polymer substrate to support a subsequent electroforming step. In watchmaking, galvanic baths containing cyanide electrolytes can be used, such as the two examples cited below. Example 1:

[0043] KCN: 18 to 35 gl -1< Au: 6.0 to 12 gl -1< (provided by KAu(CN) 6 ) Copper: 55 to 100 gl -1< Example 2:

[0044] KCN: 27 to 30 gl -1< Au: 5 gl -1< (brought by KAu(CN) 6 ) Copper: 55 gl -1< Indium: 0.8 gl -1<

[0045] Following delaminations of galvanic deposits observed, particularly in the case of cyanide electrolytes in galvanic baths used to obtain an 18-carat gold deposit, the source of the chemical incompatibility between the cyanide electrolyte and the materials used was investigated.

[0046] It has been found that compatibility is based on the nature of metal-support interactions in polymer material. These are weak physisorption bonds that can be easily cleaved in the presence of a complexing agent with strong affinities for the metal. This strong affinity can be characterized by an equilibrium constant pK f . The higher its value, the higher the stability of the complex and the metal-ligand affinity.

[0047] This equilibrium constant pK f is dependent on the complexation constant Kc or the formation constant Kf in the case of metal-ligand bonds.

[0048] The formation of the complex follows the following reaction: M t + + nL u − ↔ M L n t − nu + with : M : metal L : ligand n : number of ligands t And u : number of charges

[0049] The formation constant K f can thus be written: K f = M L n M L n

[0050] Finally, the equilibrium constant pK f can be written: pK f = − log K f

[0051] The invention advantageously uses this observation to, on the one hand, form said at least one main layer 12 on said at least one base layer 11 by electroplating using a galvanic bath not comprising cyanide ions in order to avoid any delamination and then, on the other hand, to choose a strong metal - cyanide ion affinity of said at least one base layer 11 to separate, thanks to its strong affinity, the watch component 1 from the support 10 by immersing them in a solution comprising cyanide ions.

[0052] To this end, the invention relates to a method for manufacturing a watch component 1 comprising the following steps: a. providing a support 10 made of polymer material; b. forming at least one base layer 11 on at least a portion of the support 10, said at least one base layer 11 being based on a metallic material whose equilibrium constant with respect to cyanide ions is greater than or equal to 10; c. forming at least one main layer 12 on said at least one base layer 11 (i.e. one (or more) base layer(s) 11 or on the one(s) which form(s) the upper surface) by electroplating using a galvanic bath not comprising cyanide ions in order to form a watch component 1; d. separating the watch component 1 from the support 10 by immersing them in a solution comprising cyanide ions so that the bonds of said at least one base layer 11 (i.e. one (or more) base layer(s) 11 or on the one(s) which form(s) the lower surface) with the support 10 recombine with the cyanide ions.

[0053] The pure gold deposit can therefore continue to be used to form said at least one base layer 11. Indeed, such a gold layer forms an effective layer to serve as a seat for electroplating during step c. In addition, its affinity is very strong with cyanide ions. Thus, it has been calculated that the equilibrium constant pKf of pure gold is located between 38.3 and 15.27 depending on the cyanide derivative present in the solution used in step d. During the latter, there is therefore an exchange between the cyanide ions and said at least one base layer 11 which will induce a cleavage of the metal 11 - support 10 bonds and incidentally cause the delamination of the watch component 1 with respect to the support 10.

[0054] It is understood that the watch component 1 is released from the support in a very selective manner and that the support 10 and the watch component 1 do not undergo any shock (thermal, mechanical or chemical) likely to damage them. In addition, step d can be obtained using a cyanide galvanic bath already present in the manufacturing workshop as presented in examples 1 and 2 above but without having to impose a potential difference. Only the free cyanides in the galvanic bath will interact with said at least one base layer 11. The face of the watch component 1 which was against the support 10 therefore remains very faithful to the geometry of the electroforming support 10 and no particle of a material of the support 10 remains on the watch component 1. No discoloration or more generally degradation of the metal layers 11, 12 due to the use of a chemically very active solvent will also be observed.Finally, the strong affinity of said at least one base layer 11 with the cyanide ions allows a rapid removal step d typically between 1 minute and 50 minutes. Consequently, in view of the above, the method, advantageously according to the invention, can boast a much lower production cost while making it possible to obtain high-quality watch components 1.

[0055] In the example illustrated in Figures 2 and 3, step a may comprise a first phase i intended to provide a replication tool 8 comprising in part a geometry (shape 8a to be replicated) to be reproduced of the watch component 1. Then, a second phase ii is intended to at least partially cover the replication tool 8 (in particular its shape 8a to be replicated) with a polymer material in order to form a support 10 made of polymer material with a complementary geometry (replication shape 10a) of the geometry (shape 8a to be replicated) to be reproduced of the watch component 1. The second phase ii may be obtained by plastic injection (the material of the part 10 is hot-pressed in an injection mold), by casting (the material is cast and crosslinked on the mold) or by embossing (the mold 8 is pressed onto the material 10 before drying (evaporation of the solvent), cooling, or crosslinking (chemical, photochemical).

[0056] Finally, a third phase iii is intended to release the support 10 made of polymer material from the replication tool 8 as illustrated in figure 3 . The third phase iii can be obtained by solubilization of the support 10, by thermal shock (heating or cooling whose different expansion variations for each material will release the support 10) or by mechanical shock (stretching, twisting, contraction, etc. allowing the support 10 to be released). For thermal and mechanical shocks, prior passivation of the contact surface of the tool 8 can be provided to facilitate the detachment of the support 10.

[0057] Of course, step a could be different, such as forming the support 10 in polymer material without using a replication tool 8 and / or from an injection mold. The support 10 could also be obtained from a flat substrate in a first polymer material covered with an openwork mask (obtained for example from photolithography) in a second polymer material. It is understood that the openworks, each bottom of which is formed by the flat substrate, could serve as molds for galvanic growth and whose wall shape makes it possible to obtain a three-dimensional watch component of predetermined geometry. As a non-limiting example, the support 10 could also be obtained from a flat substrate in a first polymer material covered with an openwork mask (obtained for example from photolithography) in a second polymer material.It is understood that the openworks, each bottom of which is formed by the flat substrate, could serve as molds for galvanic growth and whose wall shape makes it possible to obtain a three-dimensional watch component of predetermined geometry. Step a could also be obtained by three-dimensional printing (direct additive manufacturing of the support 10) or by laser radiation lithography (high precision of the geometry of the support 10 without the use of a mask).

[0058] Preferably, said at least one base layer 11 is based on a metallic material whose equilibrium constant with respect to cyanide ions is greater than or equal to 15. Such a metallic material may be based on gold and / or silver and / or platinum. It is therefore understood that each metallic material may be pure or in the form of the main element of an alloy of at least one other metallic material from the list and / or at least one other element not belonging to the list. By way of non-limiting example, said at least one base layer 11 may be based on a 2N gold alloy, a 3N gold alloy, a 4N gold alloy, rhodium, a nickel-zinc alloy or even a gold-nickel alloy in order to vary the colors on the watch component 1.

[0059] Step b is preferably obtained by physical vapor deposition. Of course, other deposition methods can be considered without departing from the scope of the invention. In the example illustrated in figure 4 , said at least one base layer 11 is deposited only against the replication form 10a of the support 10. The low-thickness deposition of said at least one base layer 11 makes it possible to faithfully reproduce the replication form 10a and to adhere to the support 10.

[0060] Step c is intended to form at least one main layer 12 by electroplating using a galvanic bath not comprising cyanide ions in order to form the solid metal part of the watch component 1 without delamination. In the example illustrated in Figure 5, said at least one main layer 12 is deposited from said at least one base layer 11 until it covers an upper part of the support 10. The very thick deposition of said at least one main layer 12 makes it possible to adhere to said at least one base layer 11 and to thicken the latter so as to improve the mechanical resistance of the watch component 1. Said at least one main layer 12 may be based on a noble material (precious metal such as pure gold or silver (or one of their alloys)) or less noble material (more conventional metal such as copper and / or nickel and / or chromium and / or zinc and / or pure bronze (or one of their alloys)) depending on the desired rendering or the final visibility of said at least one main layer 12.

[0061] In watchmaking, galvanic baths containing non-cyanide electrolytes can be used, such as the three examples cited below: Example 3 :

[0062] Na 3 Au(SO 3 ) 2: 10 to 12 gl -1< gold Na 2 SO 3: 0.3 to 1 mol.l -1< additives: MPS, PEI, Bi33+, Te4+ (ppm level) Example 4 :

[0063] Sulfuric acid: 60 to 70 g. l -1 < Copper sulfate: 40 to 60 g. l -1 < Copper additives: PEG, CI-, SPS40, Janus green B (ppm level) Example 5 :

[0064] Ni(NH 2 SO 3 ) 2 : 550 to 650 gl -1< NiCl 2 : 5 to 15 gl -1< Boric acid : 30 to 40 gl -1< Wetting agent Hardening agent

[0065] According to a first variant of the first embodiment, at the end of step c, the method according to the invention stops with step d, as illustrated in the example of the figure 6 , intended to release the watch component 1 from the support 10 in order to form the watch component 1 solely from said at least one base layer 11 and said at least one main layer 12.

[0066] In step d, the solution containing cyanide ions may have a cyanide ion concentration of at least 5 gl -1< in order to obtain sufficiently rapid delamination. Typically, the concentration is preferably between 5 gl -1< and 15 gl -1< , that is to say can, for example, be equal to 5 gl -1< , 6 gl -1< , 7 gl -1< , 8 gl -1< , 9 gl -1< , 10 gl -1< , 11 gl -1< , 12 gl -1< , 13 gl -1< , 14 gl -1< , 15 gl -1< , 16 gl -1< , 17 gl -1< , 18 gl -1< , 19 gl -1< , 20 gl -1< , 21 gl -1< , 22 gl -1< , 23 gl -1< , 24 gl -1< , 25 gl -1< , 26 gl -1< , 27 gl -1< , 28 gl -1< , 29 gl -1< , 30 gl -1< , 31 gl -1< , 32 gl -1< , 33 gl -1< , 34 gl -1< or 35 gl -1< . The higher the concentration, the shorter the delamination step d. The process is diffusion limited so care must be taken not to over-concentrate the solution to increase the viscosity too much. The preferred concentration is between 12 g.l -1< and 22 gl -1< .

[0067] In order to further shorten the duration of step d, agitation of the solution may be implemented in order to force the movement of the solution around the support 10 and the watch component 1 to improve delamination. Typically, if a cyanide galvanic bath, such as that of one of the examples 1 and 2 above, is used for step d, the agitation element of the galvanic bath is actuated.

[0068] In step d, the solution may have a temperature between 30°C and 60°C, i.e. may, for example, be 30°C, 31°C, 32°C, 33°C, 34°C, 35°C, 36°C, 37°C, 38°C, 39°C, 40°C, 41°C, 42°C, 43°C, 44°C, 45°C, 46°C, 47°C, 48°C, 49°C, 50°C, 51°C, 52°C, 53°C, 54°C, 55°C, 56°C, 57°C, 58°C, 59°C or 60°C. Temperature is a factor that promotes diffusion. In a particular embodiment, the temperature is 45°C.

[0069] Finally, in step d, the solution may have a basic pH of between 10 and 15, i.e. may, for example, be equal to 10, 10.5, 11, 11.5, 12, 12.5, 13, 13.5, 14, 14.5 or 15. Indeed, the basic pH of between 10 and 15 promotes demolding and makes the process safer by avoiding the risk of release of hydrocyanic acid. In a particular embodiment, the pH is between 13 and 14.

[0070] For step d, the examples of solution with free cyanides other than examples 1 and 2 above can be used: Example 6:

[0071] CuCN: 48 gl -1< KCN: 15 gl -1< KHCO 3: 385 gl -1< KOH: 5 to 10 gl -1< Example 7:

[0072] KAu(CN) 2: 11 gl -1< CuCN: 2.5 gl -1< ZNO: 2.5 gl -1< NaCN: 20 gl -1< NaOH: 5.5 gl -1< KHCO 3: 5 gl -1< EDTA: 5 gl -1< Example 8:

[0073] Au: 6 gl -1< Cu: 60 gl -1< In: 2 gl -1< KCN: 30 gl -1< NTA: 4 gl -1< Ag: 10 mg.l -1< DETA: 0.2 mol.l -1< gallium, selenium or tellurium: 5 mg.l -1< sodium hypophosphite: 0.1 gl -1< thiomalic acid: 50 mg.l -1<

[0074] This step d can in particular be used for a mass replication process in which the support 10 made of polymer material is used to form several watch components 1 during the method according to the invention. Of course, a finishing step (for example machining and / or polishing) and / or protection (for example varnishing, PVD or ALD) can be provided to make the watch component 1 suitable for being mounted in the timepiece 2 (aesthetics, geometry, etc.).

[0075] According to a second variant of the first embodiment, at the end of step d, the method according to the invention can continue and possibly stop with step e (final step) intended to form at least one decorative layer on at least a part of the watch component 1, that is to say, for example, a total covering in order to modify the aesthetic appearance of the watch component 1. Typically, this makes it possible to form said at least one main layer 12 based on a less noble metallic material such as pure copper (or one of its alloys) and then to cover (for example by another electroplating) all or part of said at least one main layer 12 with at least one decorative layer made of a more noble material such as based on a precious metal such as pure gold (or one of its alloys) in order to give a more high-end finish to the watch component 1.

[0076] According to a first variant of the second embodiment, between step c and step d, the method comprises a step α (alpha) intended to machine the watch component 1 in order to modify its shape by removing material. Advantageously according to the invention, it is thus possible to work and / or decorate and / or remove any surplus of said at least one main layer 12 while the support 10 made of polymer material is still integral with said at least one base layer 11. Step α (alpha) can, for example, make it possible to form at least one element 12a for fixing the watch component 1 as illustrated in figure 8 . As a non-limiting example, step α (alpha) could, for example, form feet of the watch component 1 forming a watch dial in order to fix the latter to a watch movement 3

[0077] As with the first embodiment, the first variant of the second embodiment stops with step d, as illustrated in the example of the figure 8 , intended to release the watch component 1 from the support 10 in order to form the watch component 1 solely from said at least one base layer 11 and said at least one main layer 12.

[0078] According to a second variant of the second embodiment, at the end of step d, the method according to the invention can continue and possibly stop with step e (final step) intended to form at least one layer 13 of decoration on at least part of the watch component 1 (total covering in the example of the figure 9) in order to modify the aesthetic appearance of the watch component 1. Typically, this makes it possible to form said at least one main layer 12 based on a less noble metallic material such as pure copper (or one of its alloys) and then to form (for example by another electroplating) to cover all or part of said at least one main layer 12 with at least one decorative layer 13 made of a more noble material such as based on a precious metal such as pure gold (or one of its alloys) in order to give a more high-end appearance to the watch component 1.

[0079] Of course, step e of the two embodiments can be obtained by another type of deposition such as, for example, physical vapor deposition, chemical vapor deposition or autocatalytic deposition. Finally, as for the other variants, a finishing step (for example machining and / or polishing) and / or protection step (for example varnishing, PVD or ALD) can be provided, after step e of the two embodiments, to make the watch component 1 suitable for being mounted in the timepiece 2 (aesthetics, geometry, etc.).

[0080] Advantageously according to the invention, said at least one base layer 11 may be based on gold and / or silver and / or platinum, step e of the two embodiments may, if desired, completely cover the watch component 1.

[0081] The invention is not limited to the embodiments and variants presented and other embodiments and variants will become apparent to those skilled in the art. Thus, the above embodiments are examples. Although the description refers to one or more embodiments, this does not necessarily mean that each reference relates to the same embodiment, or that the characteristics apply only to a single embodiment. Simple characteristics of different embodiments can also be combined and / or interchanged to provide other embodiments. Without being limiting, it may be envisaged to apply to the first embodiment a step α (alpha) of machining of the second embodiment after step d.

[0082] Furthermore, the invention cannot be limited to the materials given as examples above. Thus, the invention could also be applied with a barrier layer such as a nickel-based layer (pure or alloy) between, for example, two layers whose intermetallics are very easy to form at room temperature. As a non-limiting example, copper diffuses very easily into gold. Such a barrier layer would prevent the diffusion of copper into the gold on the watch component 1 by providing better visual stability over time. LIST OF REFERENCES

[0083] 1 - watch component 2 - timepiece 3 - watch movement 8 - replication tool 8a - form to be replicated 10 - polymer material support 10a - replication form 11 - base layer 12 - main layer 12a fixing element 13 - decoration layer

Claims

1. A method of manufacturing a timepiece component (1) comprising the following steps: a. providing a support (10) made of polymer material; b. forming at least one base layer (11) on at least a portion of the support (10), said at least one base layer (11) being based on a metallic material whose equilibrium constant with respect to cyanide ions is greater than or equal to 10; c. forming at least one main layer (12) on said at least one base layer (11) by electroplating using a galvanic bath not comprising cyanide ions in order to form a timepiece component (1); d. separating the timepiece component (1) from the support (10) by immersing them in a solution comprising cyanide ions so that the bonds of said at least one base layer (11) with the support (10) recombine with the cyanide ions.

2. Method according to the preceding claim, in which step a comprises the following phases: i. providing a replication tool (8) partly comprising a geometry (8a) to be reproduced of the watch component (1); ii. at least partially covering the replication tool (8) with a polymer material in order to form a support (10) made of polymer material with a complementary geometry (10a) of the geometry (8a) to be reproduced of the watch component (1); iii. releasing the support (10) made of polymer material from the replication tool (8).

3. Method according to claim 1 or 2, in which said at least one base layer (11) is based on a metallic material whose equilibrium constant with respect to cyanide ions is greater than or equal to 15.

4. Method according to any one of the preceding claims, wherein said at least one base layer (11) is based on gold and / or silver and / or platinum.

5. Method according to any one of the preceding claims, in which step b is obtained by physical vapor deposition.

6. Method according to any one of the preceding claims, in which, in step c, the galvanic bath not comprising cyanide ions makes it possible to deposit a material based on copper and / or silver and / or gold and / or nickel and / or chromium and / or zinc and / or bronze.

7. A method according to any one of the preceding claims, wherein, in step d, the solution comprising cyanide ions has a cyanide ion concentration of at least 5 g / l. -1 .

8. A method according to any preceding claim, wherein, in step d, the solution has a temperature of between 30°C and 60°C.

9. A method according to any one of the preceding claims, wherein, in step d, the solution has a pH of between 10 and 15.

10. Method according to the preceding claim, in which, between step c and step d, the method comprises the following step: α. machining the watch component (1) in order to modify its shape by removing material.

11. Method according to the preceding claim, in which step α makes it possible to form at least one element (12a) for fixing the watch component (1).

12. Method according to any one of the preceding claims, in which the method comprises the following final step: e. forming at least one layer (13) of decoration on at least a portion of the watch component (1) in order to modify the aesthetic appearance of the watch component (1).

13. Method according to the preceding claim, in which the decorative layer (13) is based on a precious metal.

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