CH721876A2 - ITEM WITH 3D DESIGN AND ITS MANUFACTURING PROCESS - Google Patents

Abstract

The invention also relates to the article resulting from the manufacturing process. Such an article is, for example, a watch component such as a bezel or a dial.

Description

Technical field of the invention

[0001] The invention relates to a method of manufacturing an article made of a non-electrically conductive material with said article having a 3D decoration made of a noble metal or its alloy.

Technological background

[0002] Decorations are generally applied, for example by gluing, to components made of hard, non-conductive materials such as ceramics. Decorations applied in this way have weak adhesion to the substrate, with an increased risk of detachment or peeling, particularly on components subjected to high stress, such as watch bezels.

Summary of the invention

[0003] The present invention aims to overcome the aforementioned shortcomings by proposing a method for manufacturing an article with a positive relief decoration where the risks of detachment of the decoration are eliminated.

[0004] More specifically, the invention relates to a method for manufacturing an article made of a non-electrically conductive material such as ceramic and sapphire, the article comprising at least one relief decoration made of a precious metal or its alloy, the method comprising the steps of:

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Provision of a defined draft with a surface;

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Application of a first bonding coat and then a second bonding coat on the surface;

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Electroforming deposition of a layer of the noble metal or its alloy onto the second bonding layer;

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Laser cutting of the layer of precious metal or its alloy to delimit the relief decoration;

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Application of a protective layer around the perimeter of the embossed decoration;

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Removal of the layer of noble metal or its alloy on portions not covered by the protective layer and possibly removal of the second bonding layer on said portions if the second bonding layer is made of the same noble metal or the same noble metal alloy as the layer of noble metal or its alloy;

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Removal of the protective layer;

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Removal of the first bonding layer and possibly the second bonding layer if the latter is still present following the step of removing the layer of noble metal or its alloy on the portions.

[0005] With the process according to the invention, the decoration cannot be torn off or detached from the substrate.

[0006] The present invention also relates to an article comprising at least one relief decoration overhanging a base surface, said relief decoration being made with a noble metal or its alloy and having a thickness of between 0.02 mm and 0.7 mm, preferably between 0.03 mm and 0.3 mm, said relief decoration being bonded to the base surface by a first bonding layer and by a second bonding layer, each having a thickness of between 30 and 70 nm.

[0007] Thus, the layer of precious metal or its alloy on the relief decoration has a significant thickness, up to several tenths of a millimeter. The substantial thickness of the deposited metal or alloy contributes to giving the "solid" appearance of a decoration that could have been added later, such as an appliqué, for example.

[0008] Since this invention is more specifically intended to decorate glasses, there is no risk, through friction on clothing, of wearing away the deposit, which could reveal the substrate.

[0009] Electroformed alloyed noble metal, particularly alloyed gold, has the further advantage of being harder than metallurgical alloyed gold applied to the substrate. This can provide a satin finish that is more durable over time.

Brief description of the figures

Figures 1 to 9 schematically represent the 9 steps of the process according to the invention.

Figure 10 represents a watch bezel with indices and numerals forming the 3D decorations made in the noble metal or its alloy according to the invention.

Detailed description of the invention

[0011] The invention relates to a method for making an article with at least one relief decoration made of a precious metal or its alloy. This article 1, schematically represented in Figure 9 and, for a bezel, in Figure 10, comprises a base surface 2b surmounted by at least one relief decoration 2a, which is formed of indices and numerals made of the precious metal or its alloy.

[0012] The precious metal is more specifically gold and its alloys, silver, platinum, palladium, rhodium, or other precious metals. The article may, for example, be a watch component. More specifically, it may be a case component chosen from the non-exhaustive list including a case, a case back, a bezel, a crown, a pusher, a bracelet link, a bracelet, a pin buckle, a clasp, a dial, and a hand. The process is more specifically suited for an article made of an electrically non-conductive material such as ceramic, silicon nitride, YAG, or sapphire. These materials are generally hard, with hardnesses greater than or equal to 1100 HV.

[0013] The process is illustrated in Figures 1 to 9 in 9 steps. In the first step (Fig. 1), a blank 3 of the article to be manufactured is made available. For example, this could be a bezel or a dial without the hour markers. In the case of a ceramic, this blank can be obtained by a conventional powder sintering process for ceramics, silicon nitride and YAG, or by the Verneuil process and the EFG (Edge-Defined, Film-Fed Growth) technique for sapphire. The blank 3 is defined with a surface 2, which is the face intended to contain the raised decoration.

[0014] Then, in a second optional step (fig.2), micro-drillings 6a, engravings 6b and/or undercuts 6c can be made on the surface 2 of the blank 3 to improve the anchoring of future decorations.

[0015] In a third step (Fig. 3), at least two adhesion layers 4a, 4b are preferentially deposited by PVD (Physical Vapor Deposition) on the surface 2 and in the micro-drillings 6a, engravings 6b and/or undercuts 6c. A first layer 4a is formed of Cr or Ti and a second layer 4b is formed of Au, Ag or Cu. Each layer has a thickness between 30 nm and 70 nm, with typically one layer on the order of 50 nm.

[0016] In a fourth step (Fig. 4), the noble metal or its alloy layer 5 is deposited by electroforming onto the second tack coat 4b. This layer has a thickness of between 0.02 mm and 0.7 mm, preferably between 0.03 mm and 0.3 mm. For the growth of a gold alloy in a shade between the 3N and 5N ranges (according to ISO 8654 of February 2018), the parameters are as follows:

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the bath contains 1 to 10 g.I-1 of metallic gold in the form of alkali aurocyanide;

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the bath contains 30 to 80 g.I-1 of metallic copper in the form of alkali double cyanide;

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the bath may contain from 10 mg.I-1 to 5 g.I-1 of indium metal in complexed form;

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the bath contains 15 to 35 g.I-1 of free cyanide;

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the bath temperature is maintained between 50 and 80 °C;

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the pH of the bath is maintained between 8 and 12;

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the process is carried out at current densities between 0.05 and 1.5 A.dm- 2 .

[0017] In an optional fifth step (fig.5), the upper part 5a of the noble metal layer or its alloy 5 can be subjected to a mechanical operation intended to polish, satin-finish and/or mattify this layer.

[0018] In a sixth step (fig.6), the future indexes and motifs intended to form the relief decoration 2a are laser-cut from the layer of noble metal or its alloy 5.

[0019] Next, in a seventh step (fig.7), a protective layer 7, namely a lacquer, is deposited on the future indexes and motifs 2a, leaving a layer of noble metal or its alloy 5 uncovered by lacquer on the portions 2c.

[0020] In an eighth step (fig.8), the layer of noble metal or its alloy 5 is removed from the portions 2c not covered with lacquer by immersing the blank 3 in a cyanide-based bath.

[0021] In a ninth and tenth step (Fig. 9), the lacquer 7 is removed by immersing the blank 3 in a solvent bath, Deconex 196, and the tack coats 4a, 4b at the level of the portions 2c are removed by immersing the blank 3 in a commercial bath, for example, Chrome Etch No. 1, formulated by Technic. The removal of these coats has little impact on the noble metal or its alloy layer because the thickness differences between the tack coats and the noble metal or its alloy layer are significant. Thus, removing any remaining few nanometers of the tack coats will remove proportionally little material from the thick layer of the noble metal or its alloy.

[0022] If the tack coat 4b and the noble metal or its alloy layer 5 are made of the same noble metal, only the first tack coat 4a will need to be removed in this step, the second layer 4b having already been removed in the eighth step. It should be noted that the ninth and tenth steps can be reversed.

[0023] In an optional eleventh step (not shown), the blank material can be textured to give a matte, satin, and/or patterned appearance to the surface of the material. The texturing can be carried out by laser or by a mechanical operation.

[0024] The article 1 thus obtained, represented in figure 10 for a lunette, thus presents one or more relief decorations 2a overhanging the base surface 2b with the relief decorations 2a made with the noble metal or its alloy 5.

Claims (13)

1. A method for manufacturing an article (1) made of a non-electrically conductive material such as ceramic and sapphire, the article (1) comprising at least one raised decoration (2a) made of a precious metal or its alloy, the method comprising the steps of: - Providing a blank (3) defined with a surface (2); - Deposition of a first tack coat (4a) and then a second tack coat (4b) on the surface (2); - Electroforming deposition of a layer of the precious metal or its alloy (5) onto the second tack coat (4b); - Laser cutting of the layer of precious metal or its alloy (5) to delineate the raised decoration (2a); - Deposition of a protective layer (7) around the perimeter of the raised decoration (2a); – Removal of the noble metal or its alloy layer (5) from portions (2c) not covered by the protective layer (7), and optionally removal of the second bonding layer (4b) from said portions (2c) if the second bonding layer (7) is made of the same noble metal or noble metal alloy as the noble metal or its alloy layer (5); – Removal of the protective layer (7); – Removal of the first bonding layer (4a) and optionally the second bonding layer (4b) if the latter is still present after the removal of the noble metal or its alloy layer (5) from the portions (2c). 2. Manufacturing method according to claim 1, wherein the first tack layer (4a) is formed of a layer of Cr or Ti and the second tack layer (4b) is formed of Au, Ag or Cu and wherein the first tack layer (4a) and the second tack layer (4b) are deposited by PVD. 3. A manufacturing method according to any one of the preceding claims, wherein the first bonding layer (4a) and the second bonding layer (4b) each have a thickness of between 30 and 70 nm and wherein the layer of the noble metal or its alloy (5) has a thickness of between 0.02 mm and 0.7 mm, preferably between 0.03 mm and 0.3 mm. 4. A manufacturing method according to any one of the preceding claims, comprising an additional step of making a micro-drilling (6a), an engraving (6b) and/or an undercut (6c) before the step of depositing a first tack coat (4a) and a second tack coat (4b), said micro-drilling (6a), engraving (6b) and/or undercut (6c) being anchor points of the relief decoration (2a). 5. A manufacturing process according to any one of the preceding claims, comprising an additional step of mechanical operation of the upper part (5a) of the layer of the noble metal or its alloy (5) having the purpose of polishing, satin-finishing and/or mattifying said layer (5). 6. A manufacturing process according to any one of the preceding claims, wherein the step of removing the layer of noble metal or its alloy (5) is carried out in a cyanide-based bath. 7. A manufacturing process according to any one of the preceding claims, wherein the step of removing the protective layer (7) is carried out in a solvent-based bath. 8. A manufacturing process according to any one of the preceding claims, wherein the step of removing the first tack coat (4a) and optionally the second tack coat (4b) is carried out in a commercial bath. 9. Article (1) comprising at least one relief decoration (2a) overhanging a base surface (2b), said relief decoration (2a) being made of a noble metal or its alloy and having a thickness of between 0.02 mm and 0.7 mm, preferably between 0.03 mm and 0.3 mm, said relief decoration (2) being bonded to the base surface (2b) by a first bonding layer (4a) and by a second bonding layer (4b) each having a thickness of between 30 and 70 nm. 10. Article (1) according to the preceding claim, wherein said relief decoration (2a) and the first and second bonding layers (4a,4b) open into a micro-drilling (6a), an engraving (6b) and/or an undercut (6c) made in the base surface (2b). 11. Article (1) according to claim 9 or 10, said article (1) being a watch component. 12. Article (1) according to the preceding claim, said article (1) being a bezel or a dial. 13. Article (1) according to any one of claims 9 to 12, said article (1) being made of ceramic or sapphire, silicon nitride or YAG.