Method for manufacturing watch components in batches

Abstract

To provide a method for manufacturing watch components in batches.SOLUTION: A method for manufacturing watch components in batches comprises the steps of: a) providing a substrate 1 covered with a conductive priming layer 2; b) applying a layer of a photosensitive resin 3 to the conductive layer 2 of the surface of the substrate 1; c) irradiating a resin layer 3 through a mask 4 defining the outline of a batch of components 5, as well as a grid 7 and material bridges 6; d) dissolving non-irradiated areas 3b of a photosensitive resin layer 3 to reveal the conductive layer 2 of the substrate 1 in places and form a mold; e) conformal electro-galvanic deposition of a metal layer from the conductive layer 2; f) removing the photosensitive resin layer 3 and the substrate 1 to release one cluster of components thus formed; and g) releasing the batch of components from the one cluster.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a method for manufacturing batches of metal watch components using LIGA technology.

Background Art

[0002] Methods corresponding to the above definitions are already known. Specifically, in the paper by A. B. Frazier et al. titled "Metallic Microstuctures Fabricated Using Photosensitive Polyimide Electroplating moulds" and published in Journal of Microelectromechanical systems (Vol. 2, N deg. 2, June 1993), a method for manufacturing multi-level metal structures by galvanic growth within a polyimide mold made by photolithography of a photosensitive resin layer is described.

[0003] This method includes · forming a sacrificial metal layer and an underlying layer for the subsequent galvanic growth step on a substrate; · applying a photosensitive polyimide layer; · irradiating the polyimide layer with UV radiation through a mask corresponding to the outer shape of one level of the structure to be obtained; · developing the polyimide layer by dissolving the non-irradiated portions to obtain a polyimide mold; · filling the mold with nickel by galvanic growth up to its height to obtain a substantially flat upper surface; · depositing a thin chromium layer on the entire upper surface by vacuum spraying; · depositing a new photosensitive resin layer on the chromium layer; · irradiating the resin layer through a new mask corresponding to the outer shape of the next level of the structure to be obtained; · The step of developing the polyimide layer to obtain a new mold; · The step of filling the new mold with nickel up to its height by galvanic growth; · The step of separating the multi-level structure and the polyimide mold from the sacrificial layer and the substrate; · The step of separating the multi-level structure from the polyimide mold are included.

[0004] It should be understood that the method described immediately above can be repeatedly implemented in principle to obtain a metal structure with more than two levels.

[0005] The drawback of such a method is that since many parts are mass-produced, the parts can deteriorate due to impact, clogging, and entanglement. To overcome this drawback, it is possible to sort the parts, but this is costly and time-consuming.

[0006] Another drawback of such a method is that when it is necessary to perform one or more finishing steps, complex positioning is required to correctly position the individual parts during the operation. In this case, the parts have to be reordered for each finishing stage, which is also costly and time-consuming.

Prior Art Documents

Non-Patent Documents

[0007]

Non-Patent Document 1

Summary of the Invention

[0008] The present invention solves the above-mentioned drawbacks by providing a solution that keeps components attached to each other via a grid, and is handled, worked on, and / or decorated in batches.

[0009] The present invention also enables the back surface to be cleared while keeping the components attached to the grid like a wafer, so that it is not necessary to implement complicated technical means of individually positioning the components while turning them over to perform back surface work, and work and / or decoration can be easily performed. Once the component is turned over, accurate positioning is essential for performing the intended mechanical repair work.

[0010] For this purpose, the present invention relates to a method for batch manufacturing watch components, the method comprising: a) providing a substrate covered with a conductive undercoat layer; b) applying a photosensitive resin layer to the conductive portion of the substrate surface; c) irradiating the resin layer through a mask that defines the outer shape of a batch of components, grids, and material bridges, wherein the material bridges connect the components to the grid on the non-functional surface, and the grid, material bridges, and watch components form a cluster of components; d) dissolving the non-irradiated areas of the photosensitive resin layer to expose the conductive surface of the substrate here and there to form a mold; e) conformally electrogalvanically depositing a metal layer from the conductive layer, the metal layer forming the cluster of components and reaching the level of the upper surface of the photosensitive resin layer; f) removing the photosensitive resin layer and the substrate to release the cluster of components thus formed; g) releasing the components from the cluster and including.

[0011] According to another advantageous variant of the invention, · The method includes step e') between step e) and step f), during which the resin layer and the electrodeposited metal layer are planarized to bring them to the same level, · The method · A step of repeating steps c) and d) at least once after step d) in order to obtain a mold having at least two levels, · A step of applying at least one other metal layer to at least a second level of the mold and includes · The mold has several levels, · The material bridge has the same thickness as the component, · The material bridge is thinner than the component, · The method includes a step g) of wafer finishing the front, back and / or sides of the watch component, which finishing step consists of depositing layers such as, for example, a structuring layer and / or a decorative layer, · A batch of watch components of a cluster includes a batch of the same components selected from wheels, cams, hands, levers, snails, oscillating weights, indexes or appliques, · A batch of watch components of a cluster includes a batch of different components such as wheels, cams, hands, levers, oscillating weights, snails, indexes or appliques.

[0012] The invention also relates to a batch or a cluster of watch components obtained by implementing the manufacturing method according to the invention.

Brief Description of the Drawings

[0013] Other features and advantages of the invention will become apparent from the following detailed description given by way of non-limiting example with reference to the accompanying drawings.

[0014]

Figure 1

Figure 2

DETAILED DESCRIPTION OF THE INVENTION

[0015] The present invention relates to a method for manufacturing watch components.

[0016] A watch component is understood to form a functional surface designed to cooperate with other watch parts and / or components by virtue of its functional outer shape.

[0017] The substrate 1 used in step a) of the method according to the present invention is formed, for example, by a silicon substrate. During the first step a) of the method, a conductive layer 2, i.e., a layer capable of initiating metal deposition by the galvanic method, is deposited, for example, by physical vapor deposition (PVD). Typically, the conductive layer 2 is of the Au, Ti, Pt, Ag, Cr, Pd type, or a laminate of at least two of these materials, and has a thickness of 50 nm to 500 nm. For example, the conductive layer 2 may be formed from an underlayer of chromium or titanium covered by a layer of gold or copper.

[0018] The photosensitive resin 3 used in this method is preferably a negative resin based on octofunctional (8-functional) epoxy designed to polymerize under the action of UV radiation.

[0019] According to a particular embodiment of the present invention, the resin is in the form of a dry film, and thereafter the resin is applied to the substrate 1 by lamination.

[0020] Alternatively, the photosensitive resin may be a positive photoresist designed to decompose under the action of ultraviolet light. It should be understood that the present invention is not limited to some specific types of photosensitive resins. A person skilled in the art can select a photosensitive resin suitable for their needs from all known resins suitable for UV photolithography.

[0021] During step b), a layer of resin 3 is deposited on substrate 1 to the desired thickness by any suitable means such as centrifugal coating, spin coating, spraying, etc. Typically, the thickness of the resin is between 10 μm and 1,000 μm, preferably between 30 μm and 300 μm. Depending on the desired thickness and the deposition or vapor deposition technique used, the first resin layer 3 is deposited in one or more layers.

[0022] Thereafter, the first resin layer 3 is heated, typically to between 90 and 120 °C, for a time depending on the deposition thickness, and the solvent is removed (pre-bake step). This heating dries and cures the resin.

[0023] The next step c) shown in Figure 1 consists of irradiating the first resin layer 3 with ultraviolet light through a mask 4 that defines the mold of the component to be formed, and thus the photopolymerizable area 3a and the non-photopolymerizable area 3b.

[0024] According to the present invention, during step c), the mask allows defining the outer shape of a batch of components 5, as well as the outer shapes of the grid 7 and the material bridge 6. The material bridge allows connecting the components to the grid on the non-functional surface.

[0025] In this way, the grid, the material bridge and the watch parts form a cluster of components at the end of the process.

[0026] The grid and / or the material bridge are thinner than the components, as required by a person skilled in the art.

[0027] Advantageously, the material bridge connects the component to the grid in the non-functional outer shape of the component. This means that the outer shape of the component forms a functional surface designed to cooperate with other watch parts and / or components, and thus the non-functional outer shape (or surface) can be said, by analogy, to be an outer shape that has no possibility of cooperating with other components.

[0028] To complete the photo-polymerization induced by UV irradiation, a step of annealing the first resin layer 3 (post-bake step) may be required. This annealing process is preferably carried out between 90 °C and 95 °C. The photo-polymerized area 3a becomes insensitive to most solvents. However, the non-photo-polymerized area can be dissolved by subsequent solvents.

[0029] Thereafter, the non-photo-polymerized area 3b of the first photosensitive resin layer 3 is dissolved, and the conductive layer 2 of the substrate 1 is exposed here and there. This operation is carried out by dissolving the non-photo-polymerized area 3b using a suitable solvent such as PGMEA (propylene glycol methyl ethyl acetate). Thus, a mold of the photo-polymerized photosensitive resin 3a that defines the first level of the component is created.

[0030] The next step d) shown in FIG. 1 consists of depositing a metal layer from the conductive layer 2 into the mold by electroforming or galvanic deposition until a block is formed that preferably reaches a height smaller than the height of the mold. This improves the mechanical strength during subsequent machining. The term metal in this context naturally includes metal alloys as well. Typically, the metal is selected from the group including nickel, copper, gold or silver, and from the group including gold-copper, nickel-cobalt, nickel-iron, nickel-phosphorus, or nickel-tungsten as alloys.

[0031] Optionally, after step e), this process includes step e’), which consists of machining, by a mechanical process, the metal layer forming component 5 and, optionally, the photopolymer resin layer 3a to a thickness predefined by the thickness of the component to be manufactured.

[0032] Step f) consists of releasing a cluster of components by removing the substrate, the conductive layer and the resin layer following a wet etching step or a dry etching step well known to those skilled in the art for this work.

[0033] For example, the conductive layer 2 and the substrate 1 are removed by wet etching. Thereby, a cluster of components can be released from the substrate 1 without damaging the substrate 1. In particular, in the example of a silicon substrate, this may be etched with a potassium hydroxide (KOH) solution.

[0034] When this first sequence is completed, as shown in step g), a cluster of components embedded in the resin layer is obtained.

[0035] The second sequence consists of removing the first layer 3 and the second layer 6 of resin by O2 plasma etching, separately from the wet etching of the intermediate metal layer.

[0036] Thereafter, the method may include a step of performing a machining operation, such as chamfering the edges of the visible surface of the component or threading or countersinking the component. It is obvious that this operation varies depending on the geometry of the finally obtained component.

[0037] When this step is completed, the obtained cluster of components is washed, and the cluster of components remaining fixed to the cluster can be subjected to various decorative and / or functional treatments, typically physical deposition or chemical deposition.

[0038] The components may undergo various surface finishing operations while being accurately and easily held in the cluster by the clamp. That is, the front, back, and / or side surfaces of the watch components may undergo operations while the components remain held on the wafer. The finishing steps consist of depositing layers, structuring or decorating the layers so as to cover different faces of the watch components. These operations can be functional (reinforcement, tribology, etc.) or aesthetic (coloring, patterning, etc.) using PVD or CVD.

[0039] Finally, the final step consists of releasing the components from the formed cluster. The components can be separated from the cluster using different methods such as laser cutting, stamping, mechanical breaking, etc.

[0040] According to an optional step, after step b), the resin layer 3 is machined to a certain thickness. Advantageously, this operation allows for fine control of the geometry of the part to match the scale of the substrate 1. Once the resin is thickened, a heat treatment is performed to erase the machining traces.

[0041] The above example has been described for single-level components. The method may also be applied to components having multiple levels or stages.

[0042] To do this, a multi-level mold is made by depositing at least one second conductive layer on the photopolymerizable area 3a in step c). This second conductive layer may have the same properties as the first conductive layer 2. That is, it may be Au, Ti, Pt, Ag, Cr, Pd type, or a laminate of at least two of these materials, and may have a thickness between 50 nm and 500 nm.

[0043] Thereafter, a new photosensitive resin layer is deposited on the second conductive layer to cover it and fill the openings of the previously developed resin layer.

[0044] Alternatively, it is also possible to apply the photoresist of the second resin layer so as to cover the first resin layer without the photoresist entering the opening formed at the start of the process. To obtain such a result, for example, a "solid" resin adhered by lamination can be used.

[0045] The second resin layer is irradiated through the openings of the mask that define the outer shape of the second level of the desired microstructure. In this step, it is necessary to align the mask with the openings of the first level.

[0046] A person skilled in the art may perform 3D printing to deposit the second conductive layer 5.

[0047] With such a solution, the second conductive layer can be deposited selectively and accurately, so that there is no deposit over the sidewalls of the photopolymerizable resin 3a.

[0048] The next step shown consists of depositing a second layer of photosensitive resin so as to cover the structure obtained in the previous step. The same resin is used during this step and the thickness may be greater than that deposited in step a). Generally, the thickness varies depending on the geometry of the component to be obtained.

[0049] The next step consists of irradiating the second resin layer through a mask that defines the second level of the component and dissolving the non-irradiated areas of the second photosensitive resin layer. At the end of this stage, a mold is obtained that includes the first and second levels where the first conductive layer 2 and the second conductive layer are exposed in places.

[0050] The method of the present invention is particularly advantageously applicable to the manufacture of watch components such as springs, anchors, wheels, etc. Thanks to this method, a cluster of robust and geometrically reliable components can be obtained.

[0051] The method can be used to create the entire cluster on a "wafer" scale or to create sub-assemblies of mini-clusters on the same wafer. It is understood that a "wafer" is the substrate plate used to form the cluster.

[0052] According to such a method, it is also possible to use clusters of components in the same way as the manufacture of components on a silicon wafer.

[0053] Of course, the present invention is not limited to the illustrated example, i.e., the manufacture of cams, and may be affected by various variations and modifications that will be apparent to those skilled in the art.

Claims

1. 1. A method for batch manufacturing of watch components, comprising the steps of: a) providing a substrate (1) covered with a conductive undercoat layer (2); b) applying a layer of photosensitive resin (3) onto said conductive layer (2) on the surface of said substrate (1); c) irradiating said resin layer (3) through a mask (4) defining the outline of a batch of components (5) and grids (7) and material bridges (6), said material bridges (6) connecting said components (5) to said grids (7) at their non-functional surfaces, said grids, said material bridges and said wristwatch components forming a cluster of components; d) dissolving the non-irradiated areas (3b) of the photosensitive resin layer (3) to expose portions of the conductive layer (2) of the substrate to form a mold; e) conformal electrolytic galvanic deposition of a metal layer from said conductive layer (2), said metal layer forming a component of said cluster and reaching the level of the upper surface of said photosensitive resin layer; f) removing said photosensitive resin layer and said substrate to release the components of said one cluster thus formed; g) releasing the batch of components from the one cluster; and The method according to claim 1, further comprising:

2. 2. A method according to claim 1, characterised in that it comprises a step e') between steps e) and f), during which the resin layer and the electrolytically deposited metal layer are planarised in order to bring them to the same level.

3. repeating steps c) and d) at least once after step d) to obtain a mould with at least two levels; applying at least one other metal layer to at least a second level of the mold; The method of claim 1 , comprising:

4. The method of claim 1 , wherein the mold has several levels.

5. 2. The method of claim 1, wherein the material bridge (6) has the same thickness as the component (5).

6. 2. The method of claim 1, wherein the material bridge (6) has a thickness that is less than a thickness of the component (5).

7. 2. The method according to claim 1, further comprising a step g) of wafer-finishing the front, back and / or side of the watch component (1), said finishing step consisting of depositing layers, e.g. structured and / or decorative layers.

8. The method of claim 1 , wherein the cluster of watch components includes a batch of identical parts selected from the group consisting of wheels, cams, hands, levers, snails, vibration weights, indexes, or appliques.

9. The method of claim 1 , wherein the cluster of watch components comprises a batch of different components such as wheels, cams, hands, levers, oscillating weights, snails, indexes or appliques.

10. A batch of watch components (1) obtained by carrying out a method for manufacturing a batch of watch components (1) according to claim 1.

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