Method for manufacturing an electroplating mould

Abstract

A method for manufacturing an electroplating mold, comprising the steps of: - preparing a base substrate (10), - before or after deposition and / or after texturizing at least one layer of base resin on the base substrate (10), forming an electrically conductive primer layer, characterized in that the formation of the primer layer comprises at least the steps of: i- forming, below an electrical percolation limit, a first layer (30) of electrically conductive material, ii- forming, in a subsequent step of step i-, a second layer (50) of electrically conductive material, and in that the primer layer is formed at least in the places where the first layer of conductive material is directly covered by the second layer of conductive material

Description

Technical field of the invention

[0001] The present invention relates generally to the manufacture of molds for forming metal parts by electroplating, that is, by galvanic or autocatalytic metal growth (by electrodeposition or deposition by a current-free process called "electroless" or autocatalytic deposition, which creates metal deposits by autocatalytic chemical reduction of metal cations in a liquid bath). Such mold manufacturing typically uses UV photolithography techniques where photosensitive resin is first deposited on a substrate and then irradiated through a mask to allow for selective etching of this resin in order to generate mold impressions in the resin. The present invention also relates to the formation of metal parts in the aforementioned molds. State of the art

[0002] In the prior art of photolithographic mold making, document EP1835339A1 is known to disclose steps for developing resin deposited on a metallic substrate to form cavities for growing a metallic deposit to create complex-shaped metal parts. Once the resin is deposited, the process typically includes one or more annealing steps ("pre-bake" and / or "post-bake") before further developing the resin. The entire mold-making process can be complex. Furthermore, since the base substrate is metallic, its entire surface can potentially interact during electrodeposition, which can lead to unwanted or unintended deposits. It should also be noted that resin adhesion to the metallic base substrate can be problematic (with delamination, for example). Description of the invention

[0003] One object of the present invention is to address the disadvantages of the prior art mentioned above and in particular, first of all, to propose a simple manufacturing process, and / or one that can allow adjustment of the areas on which electrodeposition can be carried out, and / or where the resin adheres correctly to the desired areas and / or where the parts exhibit a better manufacturing quality.

[0004] To this end, a first aspect of the invention relates to a method for manufacturing an electroplating mold, comprising the steps of: to prepare a base substrate, before or after deposition and / or after texturizing at least one layer of base resin on the substrate, to form a primer layer, electrically conductive and arranged to initiate galvanic growth in the electroplating mold, characterized: in that the formation of the primer layer includes at least the steps of: i- forming, below an electrical percolation limit, a first layer of electrically conductive material, ii- forming, at a later stage of stage i-, a second layer of electrically conductive material, and in that the primer layer is formed at least in places where the first layer of conductive material is directly covered by the second layer of conductive material.

[0005] The first layer of electrically conductive material is formed below a percolation limit, that is, below the percolation threshold that prevents electrical conductivity, even if an intrinsically electrically conductive material is used (meaning that the first layer, made of electrically conductive material, is not thick or homogeneous enough to conduct electricity). It should be noted that the initiator layer (from which metal growth can begin) is only truly formed where the first layer of conductive material is directly overlain by the second layer of conductive material. Consequently, the first layer alone is not sufficiently thick and / or conductive to form the initiator layer.The first layer of conductive material can provide a good surface for the resin (or at least ensure proper resin adhesion), and / or it can prevent metallic growth (in areas not covered by the second layer of conductive material). All of this contributes to a more flexible process and / or allows for greater mold design possibilities. The primer layer (the superposition of the first and second layers of conductive material) can restore conductivity to the mold cavity if resin residue is present as contamination, or it can create a cavity cavity suitable for galvanic growth if the substrate is doped silicon, aluminum, or stainless steel.The primer layer (the superposition of the first and second conductive layers) can also make the upper surface of the resin conductive. It's also worth noting that less conductive material is deposited on the sides of the resin cavities, resulting in more homogeneous metal growth and higher-quality parts.

[0006] The manufacturing process of the electroplating mold can be defined by the following characteristics, taken individually or in combination.

[0007] In one embodiment, the base substrate comprises a conductive surface to be coated with resin. In particular, when electrodeposition or galvanic growth is planned, such a conductive surface allows the parts to be connected to each other at the electrode. Conversely, the conductive surface may itself be unsuitable for electrodeposition or galvanic growth. For example, nickel, iron, chromium, aluminum, or any other metal that spontaneously oxidizes on its surface could be used. This conductive surface could also serve as a sacrificial layer to separate the wafer from the parts by dissolving the wafer. In this latter case, the non-percolated layers will be made of materials suitable for galvanic growth (such as gold) and will be conductive or connected to each other via the conductive surface. It should be noted that the conductive surface is optional, especially if autocatalytic growth is planned.

[0008] In one embodiment, the base substrate comprises a conductive layer onto which the base resin layer can be deposited. In another embodiment, the formation of the first layer of electrically conductive material below an electrical percolation limit is carried out after the deposition (and after the texturing of said at least one base resin layer) onto the base substrate.

[0009] According to one embodiment, the step of forming, below an electrical percolation limit, a first layer of electrically conductive material consists of using an electrically conductive material, but depositing it so thinly and / or so insufficiently that the first layer itself does not conduct electricity.

[0010] According to one embodiment, the steps consist of: i- form, below an electrical percolation limit, a first layer of electrically conductive material, ii- form, at a later stage of stage i-, a second layer of electrically conductive material, are distinct, and / or implemented at different times, and / or separated by an intermediate step (for example, resin deposition and / or resin structuring and / or engraving).

[0011] In one embodiment, the second layer of electrically conductive material is formed below an electrical percolation limit. In another embodiment, neither the first layer (alone) nor the second layer (alone) conducts electricity. In yet another embodiment, the step of forming the second layer of electrically conductive material below an electrical percolation limit involves using an electrically conductive material, but depositing it so thinly and / or so insufficiently that the second layer itself does not conduct electricity.

[0012] According to one embodiment, the primer layer is formed only in places where the first layer of conductive material is directly covered by the second layer of conductive material.

[0013] In one embodiment, the formation of the first layer of electrically conductive material below an electrical percolation limit is carried out at least partially on a resin-free base surface. In other words, the first layer of electrically conductive material is deposited directly onto the base substrate (e.g., silicon).

[0014] In one embodiment, the formation of the first layer of electrically conductive material below a certain electrical percolation limit is carried out before the deposition of said base resin layer onto the substrate. This implementation is suitable for achieving autocatalytic growth, or for rendering the substrate surface fully conductive only after the formation of the second layer.

[0015] According to one embodiment, the formation, below an electrical percolation limit, of the first layer of electrically conductive material is carried out after the deposition of said base resin layer on the substrate.

[0016] According to one embodiment, the formation, below an electrical percolation limit, of the first layer of electrically conductive material is carried out after the texturing of said base resin layer.

[0017] According to one embodiment, the formation, below an electrical percolation limit, of the first layer of electrically conductive material is carried out before the deposition of a subsequent layer of resin on the base resin.

[0018] According to one embodiment, the formation, preferably below an electrical percolation limit, of the second layer of electrically conductive material is carried out after the deposition and after the texturing of a subsequent layer of resin on the base resin.

[0019] According to one embodiment, the first layer of electrically conductive material and / or the second layer of electrically conductive material is made of, or comprises, gold, and / or platinum, and / or iron, and / or palladium, and / or silver, and / or copper, and / or nickel, and / or chromium, and / or titanium, and / or tantalum.

[0020] According to one embodiment, the first layer of electrically conductive material and / or the second layer of electrically conductive material is / are deposited by a vapor phase deposition process (of the PVD type).

[0021] According to one embodiment, at least one of the first layer of electrically conductive material and of the second layer of electrically conductive material is deposited by an autocatalytic process, and preferably the second layer of electrically conductive material is deposited by an autocatalytic process, such as a Nickel Phosphorus bath for example.

[0022] According to one embodiment, the first layer of electrically conductive material, and preferably the second layer of electrically conductive material, has a thickness of less than 3 nm, preferably less than 2 nm.

[0023] According to one embodiment, the second layer of electrically conductive material is a catalytic deposit and has a thickness between 3 µm and 7 µm.

[0024] According to one embodiment, the first layer of electrically conductive material has an electrical resistance greater than 3.10 3< ohms, preferably 1.10 4< ohms, preferably greater than 1.10 5< ohms, when measured between two measuring points separated by 5 mm ± 0.5 mm, under a voltage between 5 V and 15 V.

[0025] According to one embodiment, the first layer is formed of a first electrically conductive material and / or the second layer is formed of a second electrically conductive material, different from the first electrically conductive material.

[0026] A second aspect of the invention may relate to a method for manufacturing a metal part, preferably a watch or jewelry component, by electroplating, comprising the steps of: to manufacture an electroplating mold with the process of manufacturing an electroplating mold according to the first aspect, to manufacture the metal part by electroplating or by electrodeposition, by initiating a galvanic growth in the electroplating mold from the conductive primer layer.

[0027] According to one embodiment, the process includes a step of releasing the metal part, including for example the dissolution of a sacrificial layer, for example a conductive surface initially present on the base substrate. Description of the figures

[0028] Other features and advantages of the present invention will become more apparent upon reading the following detailed description of embodiment(s) of the invention given by way of non-limiting example(s) and illustrated by the accompanying drawings, in which: [ fig. 1 ] represents a first step in a process for manufacturing an electroplating mold with the supply of a basic substrate; [ fig. 2 ] represents a second step in the manufacturing process of an electroplating mold, involving the deposition of a first layer of photosensitive resin onto the base substrate; [ fig. 3 ] represents a third step in the manufacturing process of an electroplating mold with irradiation of the first layer of photosensitive resin through a first mask; [ fig. 4 ] represents a fourth step in the manufacturing process of an electroplating mold with the formation, by directional deposition below an electrical percolation limit, of a first layer of electrically conductive material on the first layer of textured or developed photosensitive resin; [ fig. 5 ] represents a fifth step in the manufacturing process of an electroplating mold, involving the deposition of a second layer of photosensitive resin onto the first layer of electrically conductive material; fig. 6 ] represents a sixth step in the manufacturing process of an electroplating mold with irradiation of the second layer of photosensitive resin through a second mask; fig. 7 ] represents a seventh step in the process of manufacturing an electroplating mold with the formation, optionally below an electrical percolation limit, of a second layer of electrically conductive material on the second layer of textured or developed photosensitive resin; [ fig. 8 ] represents an alternative implementation of the seventh step in the manufacturing process of an electroplating mold of the figure 7 with the formation, optionally below an electrical percolation limit, of the second layer of electrically conductive material on the second layer of textured or developed photosensitive resin; [ fig. 9 ] represents the beginning of a step in a manufacturing process by electroplating a watch part in the electroplating mold of the figure 7 Or 8 ; fig. 10 ] represents a later stage in the electroplating manufacturing process of a watch component in the electroplating mold of the figure 7 Or 8 ; fig. 11 ] represents a final stage in the electroplating manufacturing process of a watch component in the electroplating mold of the figure 7 Or 8 . Detailed description of implementation method(s)

[0029] There figure 1 This represents the first step in a process for manufacturing an electroplating mold, involving the supply of a basic substrate 10, which can, for example, be a silicon wafer 10a, or any other non-electrically conductive compound, and an optional conductive surface 10b (for example, nickel, iron, chromium, or aluminum). The optional conductive surface 10b is useful when metal growth by electrodeposition or galvanic growth is planned.

[0030] There figure 2 This represents the second step in the manufacturing process of an electroplating mold, involving the deposition of a first layer of photosensitive resin 20 onto the base substrate 10. This can be achieved by spin coating or by applying a "ready-to-deposit" resin film, also known as a "Thick Film Dry Sheet." The photosensitive resin can be a SU-8 type resin. The resin thickness can range from 5 µm to 1000 µm, for example.

[0031] There figure 3 represents a third step in the manufacturing process of an electroplating mold with irradiation of the first layer of photosensitive resin 20 through a first mask 110. As shown in the figure 3 , in the first layer of photosensitive resin 20, exposed portions 21 and unexposed portions 22 are obtained. Heating or annealing can be carried out and the unexposed portions 22 can then be dissolved with the use of a solvent.

[0032] There figure 4 This represents a fourth step in the manufacturing process of an electroplating mold, involving the formation, below an electrical percolation limit, of a first layer 30 of electrically conductive material on the first layer of textured or developed photosensitive resin 20. Physical vapor deposition (PVD) is possible, and preferably directional PVD to minimize deposits on the resin's edges. The first layer 30 of electrically conductive material may be made of, or comprise, gold, and / or platinum, and / or iron, and / or palladium, and / or silver, and / or copper, and / or nickel, and / or chromium, and / or titanium, and / or tantalum.

[0033] Preferably, this step of forming, below an electrical percolation limit, the first layer 30 of electrically conductive material consists of using an electrically conductive material, but depositing it so thinly and / or so insufficiently that the first layer 30 itself does not conduct electricity.

[0034] For example, the parameters of the physical vapor phase deposition can be adjusted so that the first layer 30 of electrically conductive material has a thickness of less than 10 nm, preferably less than 5 nm, preferably less than 2 to 3 nm.

[0035] It should be noted that the fourth step in the electroplating mold manufacturing process, involving the formation of the first layer 30 of electrically conductive material, results in the deposition of this first layer 30 of electrically conductive material at the bottom of the cavities and on the remaining portions of the first layer of textured or developed photosensitive resin 20. Specifically, it is advisable not to deposit any conductive material on the sides of the cavities of the first layer of textured or developed photosensitive resin 20.

[0036] There figure 5 This represents a fifth step in the manufacturing process of an electroplating mold, involving the deposition of a second layer of photosensitive resin 40 onto the first layer 30 of electrically conductive material. Here again, SU-8 type photosensitive resin can be used.

[0037] There figure 6 represents a sixth step in the manufacturing process of an electroplating mold with irradiation of the second layer of photosensitive resin 40 through a second mask 120. As shown in the figure 6 , in the second layer of photosensitive resin 40, exposed portions 41 and unexposed portions 42 are obtained. Heating or annealing can be carried out and the unexposed portions 42 can then be dissolved with the use of a solvent.

[0038] There figure 7 represents a seventh step in the manufacturing process of an electroplating mold with the formation, optionally below an electrical percolation limit, of a second layer 50 of electrically conductive material on the second layer of textured or developed photosensitive resin 40. On the figure 7 The second layer, 50, of electrically conductive material can be formed by autocatalytic deposition, using the first layer, 30, of electrically conductive material as an autocatalytic initiator layer. For example, the part can be deposited in an electroless bath such as nickel phosphorus. Platinum, palladium, or iron nanoparticles will initiate the deposition of a conductive nickel phosphorus layer. The deposit can be nickel phosphorus with a thickness of 5 nm to 2 microns to be conductive.

[0039] There figure 8 represents an alternative implementation of the seventh step in the manufacturing process of an electroplating mold of the figure 7 with the formation, optionally below an electrical percolation limit, of the second layer 50 of electrically conductive material on the second layer of textured or developed photosensitive resin 40. Physical vapor deposition (PVD) may be provided. The second layer 50 of electrically conductive material may be made of, or comprise, gold, and / or platinum, and / or palladium, and / or iron, and / or silver, and / or copper, and / or nickel, and / or chromium, and / or titanium, and / or tantalum.

[0040] Preferably, this step of forming, below an electrical percolation limit, the second layer 50 of electrically conductive material consists of using an electrically conductive material, but depositing it so thinly and / or so insufficiently that the second layer 50 itself does not conduct electricity.

[0041] For example, the parameters of the physical vapor deposition can be adjusted so that the second layer 50 of electrically conductive material has a thickness of less than 10 nm, preferably less than 5 nm, preferably less than 2 nm.

[0042] It should be noted that the seventh step in the electroplating mold manufacturing process, involving the formation of the second layer 50 of electrically conductive material, results in the deposition of this second layer 50 of electrically conductive material at the bottom of the cavities and on the remaining portions of the second layer of textured or developed photosensitive resin 40, and / or at the bottom of the cavities and on the remaining portions of the first layer of textured or developed photosensitive resin 20. In particular, it is advisable not to deposit any conductive material on the sides of the cavities of the first layer of textured or developed photosensitive resin 20 and / or on the sides of the cavities of the second layer of textured or developed photosensitive resin 40.

[0043] At the end of the stage of the figure 7 Or 8It can be noted that the second layer 50, made of electrically conductive material, is directly deposited on certain parts of the first layer 30, also made of electrically conductive material. This superposition results in a perfectly electrically conductive primer layer, ideally suited to initiate galvanic or metallic growth for manufacturing a part in the mold. figures 7 Or 8 .

[0044] It can be noted that figure 7 , the upper parts of the second layer of textured or developed photosensitive resin 40 are free of any conductive material, so that there can be no metallic growth from these upper surfaces.

[0045] It can be noted that figure 8 , the upper parts of the second layer of textured or developed photosensitive resin 40 are only covered by the second layer 50 of electrically conductive material, formed below the electrical percolation limit, so that these upper surfaces are not electrically conductive and there can be no metallic growth from these upper surfaces.

[0046] There figure 9 represents the beginning of a step in an electroplating manufacturing process of a watch part 100 in the electroplating mold of the figure 7 Metallic growth begins only from the bottom of the impressions formed in the first layer of photosensitive resin 20, from the priming layer formed by the superposition of the second layer 50 of electrically conductive material and the first layer 30 of electrically conductive material. In the case of electrodeposition, the conductive surface 10b of the figure 1 allows all the imprint bases to be electrically connected to each other and to a terminal of a current generator. In the case of autocatalytic growth, the conductive surface 10b of the figure 1 can be omitted.

[0047] There figure 10 represents a further step in the electroplating manufacturing process of the watch part 100 in the electroplating mold of the figure 7 The top level of the 100-piece timepiece has exceeded figure 11 the upper surface of the first layer of photosensitive resin 20, and the metallic growth continues homogeneously. It should be noted that the central cavities of the upper layer of resin 40 are connected to each other at points other than the cutting plane, so that their bottoms are electrically connected to each other.

[0048] There figure 11 represents the end of the electroplating manufacturing process of the watch part in the electroplating mold of the figure 7 Typically, this occurs after a grinding step to obtain a flat and / or homogeneous surface for the watch part 100. It can be noted that the upper surface of the watch part 100 is flush with the upper parts of the second layer of photosensitive resin 40. The watch part 100 can be a gear train component, a toothed wheel, a structural component, a mainplate, a bridge, a decorative component, a dial, a hand, a cam-type component, a lever, or a spring... Industrial application

[0049] A manufacturing process according to the present invention, and its manufacture, are capable of industrial application.

[0050] It will be understood that various modifications and / or improvements obvious to a person skilled in the art can be made to the different embodiments of the invention described in this description without departing from the scope of the invention.

[0051] The different application cases for forming parts in molds according to the invention can be summarized as follows.

[0052] In the case of electrodeposition or galvanic growth, a conductive surface must be present before resin deposition (though not necessarily for autocatalytic (electroless) growth, as explained below) to connect the molds or impressions to each other and to the electrode. However, this conductive surface may be unsuitable for galvanic growth (such as nickel, iron, chromium, aluminum, or any other metal that spontaneously oxidizes on its surface; this conductive surface could also serve as a sacrificial layer to separate the wafer from the parts by dissolving it). In this latter case, the non-percolated layers subsequently deposited will be made of materials suitable for galvanic growth (such as gold) and will conduct to each other thanks to the conductive surface.

[0053] A standard wafer can be designed with a conductive base layer suitable for galvanic growth. Selective metallization on the structured resin layers is performed in two stages using two non-percolated PVD coatings. The first PVD coating is applied after the first resin layer is deposited, and the second PVD coating is applied after the second resin layer is deposited.

[0054] A standard wafer can be designed with a conductive base layer suitable for galvanic growth. Selective metallization on the structured resin layers is performed in two stages: first, a non-percolated, catalytic PVD deposition, and then an autocatalytic or electroless deposition (nickel-phosphorus or copper, for example). The first non-percolated deposition is applied after the first resin layer, and the autocatalytic or electroless deposition is applied after the deposition and structuring of the second resin layer, on the catalytic surfaces.

[0055] In the case of autocatalytic deposition for part formation, the mold can be made from a plate that may have no initial conductive or catalytic surface. The first layer of resin can be deposited, followed by a first non-percolating catalytic layer on top of this structured layer, within the openings. The second layer of resin can then be deposited and structured, followed by catalytic or electroless growth to cover the first non-percolating layer with a second, thicker layer, thus forming the parts in the molds.

Claims

1. A method for manufacturing an electroplating mold, comprising the steps of: - obtaining a base substrate (10), - before or after deposition and / or after texturizing at least one layer of base resin on the base substrate (10), forming a primer layer, electrically conductive and arranged to initiate galvanic growth in the electroplating mold, characterized: in that the formation of the primer layer comprises at least the steps of: i- forming, below an electrical percolation limit, a first layer (30) of electrically conductive material, ii- forming, at a later stage of step i-, a second layer (50) of electrically conductive material, and in that the primer layer is formed at least in places where the first layer of conductive material is directly covered by the second layer of conductive material.

2. Method of manufacturing an electroplating mold according to claim 1, wherein the second layer (50) of electrically conductive material is formed below an electrical percolation limit.

3. Method of manufacturing an electroplating mold according to any one of claims 1 or 2, wherein the primer layer is formed only in places where the first layer of conductive material is directly covered by the second layer of conductive material.

4. Method of manufacturing an electroplating mold according to any one of claims 1 to 3, wherein the formation, below an electrical percolation limit, of the first layer (30) in electrically conductive material is carried out at least partially on a resin-free base surface.

5. Method of manufacturing an electroplating mold according to any one of claims 1 to 4, wherein the formation, below an electrical percolation limit, of the first layer (30) of electrically conductive material is carried out before the deposition of said base resin layer on the base substrate (10).

6. Method of manufacturing an electroplating mold according to any one of claims 1 to 4, wherein the formation, below an electrical percolation limit, of the first layer (30) of electrically conductive material is carried out after the deposition of said base resin layer on the base substrate (10).

7. Method of manufacturing an electroplating mold according to claim 6, wherein the formation, below an electrical percolation limit, of the first layer (30) in electrically conductive material is carried out after the texturing of said base resin layer.

8. Method of manufacturing an electroplating mold according to claim 6 or 7, wherein the formation, below an electrical percolation limit, of the first layer (30) of electrically conductive material is carried out before the deposition of a subsequent layer of resin on the base resin.

9. Method of manufacturing an electroplating mold according to any one of claims 1 to 8, wherein the formation, preferably below an electrical percolation limit, of the second layer (50) in electrically conductive material is carried out after the deposition and after the texturing of a subsequent layer of resin on the base resin.

10. Method of manufacturing an electroplating mold according to any one of claims 1 to 9, wherein the first layer (30) of electrically conductive material and / or the second layer (50) of electrically conductive material is made of, or comprises, gold, and / or platinum, and / or iron, and / or palladium, and / or silver, and / or copper, and / or nickel, and / or chromium, and / or titanium, and / or tantalum.

11. Method of manufacturing an electroplating mold according to any one of claims 1 to 10, wherein the first layer (30) of electrically conductive material and / or the second layer (50) of electrically conductive material is deposited by a vapor phase deposition (PVD) process.

12. Method of manufacturing an electroplating mold according to any one of claims 1 to 11, wherein at least one of the first layer (30) of electrically conductive material and of the second layer (50) of electrically conductive material is deposited by an autocatalytic process, and preferably wherein the second layer (50) of electrically conductive material is deposited by an autocatalytic process.

13. Method for manufacturing an electroplating mold according to any one of claims 1 to 12, wherein the first layer (30) of electrically conductive material, and preferably the second layer (50) of electrically conductive material, has a thickness of less than 3 nm, preferably less than 2 nm.

14. A method for manufacturing an electroplating mold according to any one of claims 1 to 13, wherein the first layer (30) of electrically conductive material has an electrical resistance greater than 3.10 3 ohms, preferably 1.10 4 ohms, preferably greater than 1.10 5 ohms, during a resistance measurement carried out between two measuring points separated by 5 mm ± 0.5 mm, under a voltage between 5 V and 15 V.

15. Method of manufacturing a metal part, preferably a watch or jewelry part (100), by electroplating, comprising the steps of: - manufacturing an electroplating mold with the method of manufacturing an electroplating mold according to any one of claims 1 to 14, - manufacturing the metal part by electroplating or by electrodeposition, by initiating galvanic growth in the electroplating mold from the conductive primer layer.

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