How to batch manufacture watch components

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 in 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 to its height to obtain a substantially flat upper surface; · depositing a thin chromium layer over the entire upper surface by vacuum spraying; · depositing a new photosensitive resin layer over 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 new mold is filled with nickel up to its height by galvanic growth, • A step of separating the multilevel structure and polyimide mold from the sacrificial layer and substrate, • Steps to separate the multi-level structure from the polyimide mold and Includes.

[0004] It should be understood that, in principle, the method described above can be repeatedly performed to obtain metal structures of two or more levels.

[0005] The drawback of this method is that, because many parts are manufactured in large quantities, they can deteriorate due to impact, jamming, and entanglement. While it is possible to overcome this drawback by selecting the parts, this is costly and time-consuming.

[0006] Another drawback of this method is that if more than one finishing step is required, complex positioning is necessary to correctly position the individual parts during the process. In this case, the parts must be reordered for each finishing stage, which also incurs costs and time. [Prior art documents] [Non-patent literature]

[0007] [Non-Patent Document 1] AB Frazier et al. entitled, “Metallic Microstuctures Fabricated Using Photosensitive Polyimide Electroplating molds,” Journal of Microelectromechanical systems (Vol. 2, N deg. 2, June 1993) [Overview of the project]

[0008] The present invention solves the aforementioned drawbacks by providing a solution that allows components to remain attached to each other via a grid, and to be handled, worked on, and / or decorated in batches.

[0009] The present invention also allows for the back side of components to be cleared while keeping them attached to the grid like a wafer, thus facilitating work and / or decoration without the need to implement complex technical means of individually positioning components while flipping them over for back-side work. Once components are flipped over, precise positioning is essential for performing the intended mechanical rework.

[0010] To this end, the present invention relates to a method for batch manufacturing watch components, the method being: a) A step of providing a substrate covered with a conductive undercoat layer, b) The step of applying a photosensitive resin layer to the conductive portion of the substrate surface, c) A step of irradiating a resin layer through a mask that defines the outline of a batch of components, grids, and material bridges, wherein the material bridges connect components to the grid on a non-functional surface, and the grids, material bridges, and watch components form a cluster of components. d) A step of dissolving the non-irradiated areas of the photosensitive resin layer in order to expose the conductive surface of the substrate in places and form a mold, e) A step of conformally electrogalvanically depositing a metal layer from a conductive layer, wherein the metal layer reaches the level of the upper surface of the photosensitive resin layer, forming a component of the cluster. f) A step of removing the photosensitive resin layer and the substrate in order to release the components of the cluster thus formed, g) Steps to release components from the cluster and Includes.

[0011] According to other advantageous modifications of the present 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 is, - To obtain a mold having at least two levels, the steps of step c) and step d) are repeated at least once after step d), The steps include: applying at least one other metal layer to at least a second level of the mold; Includes, The mold has several levels, • The material bridge has the same thickness as the component. • Material bridges are thinner than the components. The method includes step g) finishing the wafer of the front, back and / or sides of the watch component, which finishing step consists of depositing layers such as a structural layer and / or decorative layer, • A watch component cluster includes a batch of the same component selected from wheels, cams, hands, levers, snails, oscillating weights, indices, or appliqués. A watch component cluster includes a batch of different components such as wheels, cams, hands, levers, oscillating weights, snails, indices, or appliqués.

[0012] The present invention also relates to a batch or cluster of watch components obtained by carrying out the manufacturing method according to the present invention. [Brief explanation of the drawing]

[0013] Other features and advantages of the present invention will become apparent from the following detailed description, given as non-limiting examples with reference to the accompanying drawings.

[0014] [Figure 1] The manufacturing process according to the present invention is schematically shown. [Figure 2] An example of a class of components obtained using the method according to the present invention is shown.

Best Mode for Carrying Out the Invention

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

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

[0017] The substrate 1 used in step a) of the method according to the present invention is formed of, for example, a silicon substrate. During the first step a) of the method, a conductive layer 2, that is, a layer capable of initiating metal deposition by a galvanic method, is deposited, for example, by physical vapor deposition (PVD). Typically, the conductive layer 2 is a laminate of Au, Ti, Pt, Ag, Cr, Pd type, or 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-type resin based on an 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-type photoresist designed to decompose under the action of ultraviolet light. It should be understood that the present invention is not limited to a few specific types of photosensitive resins. Those 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 the substrate 1 to a desired thickness by any suitable means, such as centrifugal coating, spin coating, or spraying. 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] Subsequently, the first resin layer 3 is heated to a temperature typically between 90 and 120°C for a time corresponding to the deposition thickness, and the solvent is removed (pre-bake stage). This heating dries and hardens the resin.

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

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

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

[0026] As those skilled in the art would require, the grid and / or material bridges are thinner than the components.

[0027] Advantageously, material bridges connect components to a grid in the non-functional form of the component. This means that the form of the component forms a functional surface designed to work with other watch parts and / or components, and therefore the non-functional form (or surface) can be said by analogy to the form that has no possibility of working with other components.

[0028] To complete the UV-induced photopolymerization, a post-bake step may be required to anneal the first resin layer 3. This annealing step is preferably carried out at a temperature between 90°C and 95°C. The photopolymerized area 3a becomes insensitive to most solvents. However, the non-photopolymerized areas may be dissolved by subsequent solvents.

[0029] Subsequently, the non-photopolymerized areas 3b of the first photosensitive resin layer 3 are dissolved, partially exposing the conductive layer 2 of the substrate 1. This process is carried out by dissolving the non-photopolymerized areas 3b using a suitable solvent such as PGMEA (propylene glycol methyl ethyl acetate). In this way, a mold of the photopolymerizable photosensitive resin 3a that defines the first level of the component is created.

[0030] The next step d) shown in Figure 1 involves 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 less than the height of the mold. This results in good mechanical strength for subsequent machining. The term metal in this context naturally includes metal alloys. Typically, the metal is selected from the group including nickel, copper, gold, or silver, and the group including gold-copper, nickel-cobalt, nickel-iron, nickel-phosphorus, or nickel-tungsten as alloys.

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

[0032] Step f) consists of freeing the components of one cluster by removing the substrate, conductive layer and resin layer following a wet etching step or a dry etching step, the procedures of which are well known to those skilled in the art.

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

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

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

[0036] The method may then include steps of performing machining operations, such as chamfering the visible edges of the component or threading or countersinking the component. It is clear that these operations will vary depending on the final geometric shape of the component.

[0037] Once this step is complete, the resulting cluster components are cleaned, and the components of that cluster, while still fixed to the cluster, may undergo various decorative and / or functional treatments, typically physical or chemical deposition.

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

[0039] Finally, the last step consists of freeing the components from the formed cluster. The components can be separated from the cluster using different methods, such as laser cutting, stamping, or mechanical fracture.

[0040] In an optional step, after step b), the resin layer 3 is machined to a certain thickness. Advantageously, this process allows for precise control of the part's geometric shape to match the scale of the substrate 1. Once the resin is thickened, heat treatment is performed to eliminate any traces of machining.

[0041] The above examples have been described for single-level components. The methods may also be applied to components with multiple levels or stages.

[0042] To accomplish this, a multilevel mold is created by depositing at least one second conductive layer on the photopolymerization 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 a laminate of Au, Ti, Pt, Ag, Cr, Pd type, or at least two of these materials, and may have a thickness between 50 nm and 500 nm.

[0043] Subsequently, a new photosensitive resin layer is deposited on top of the second conductive layer, covering it and filling the openings in the previously developed resin layer.

[0044] Alternatively, the photoresist of the second resin layer can be applied so as to cover the first resin layer without the photoresist penetrating the openings formed at the start of the process. To achieve such a result, a "solid" resin bonded by lamination, for example, may be used.

[0045] The second resin layer is irradiated through an aperture in a mask that defines the second level outline of the desired microstructure. In this step, the mask needs to be aligned with the first level aperture.

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

[0047] This solution allows for the selective and precise deposition of the second conductive layer, thus preventing the presence of deposits across the sidewalls of the photopolymerized resin 3a.

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

[0049] The next step involves irradiating the second resin layer through a mask that defines the second level of the component, and dissolving the unirradiated areas of the second photosensitive resin layer. At the end of this step, a mold is obtained that includes the first and second levels with the first conductive layer 2 and the second conductive layer partially exposed.

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

[0051] The method can be used to create an entire cluster on a "wafer" scale, or to create a subassembly of mini-clusters on the same wafer. A "wafer" is understood to be the substrate plate used to form the cluster.

[0052] This method also allows for the use of component clusters in a similar manner to how components are manufactured on silicon wafers.

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

Claims

1. A method for batch manufacturing watch components, a) A step of providing a substrate (1) covered with a conductive layer (2), b) The step of providing a photosensitive resin layer (3) on the conductive layer (2) on the surface of the substrate (1), c) A step of irradiating the photosensitive resin layer (3) through a mask (4) that defines the outline of a batch of watch components (5) and grids (7) and material bridges (6), wherein the material bridges (6) connect the watch components (5) to the grids (7) on a non-functional surface, and the grids (7), material bridges (6), and watch components (5) form a cluster of components, d) A step of dissolving the non-irradiated area (3b) of the photosensitive resin layer (3) in order to expose the conductive layer (2) of the substrate in some places and form a mold, e) A step of conformally electrolytically depositing a metal layer from the conductive layer (2), wherein the metal layer reaches the level of the upper surface of the photosensitive resin layer, forming the components of the one-cluster. f) A step of removing the photosensitive resin layer (3) and the substrate (1) in order to release the components of the cluster thus formed, wherein the components of the cluster undergo finishing work for the watch component (5), g) Releasing the watch component (5) of the batch from the cluster. A method characterized by including the following.

2. The method according to claim 1, characterized in that a step e') is included between step e) and step f), and during step e'), the photosensitive resin layer (3) and the deposited metal layer are planarized in order to bring the photosensitive resin layer (3) and the deposited metal layer to the same level.

3. - To obtain a mold having at least two levels, the step of repeating steps c) and d) at least once after step d), - The step of providing at least one other metal layer at at least a second level of the mold. The method according to claim 1, characterized by including

4. The method according to claim 1, wherein the mold has multiple levels.

5. The method according to claim 1, wherein the material bridge (6) has the same thickness as the watch component (5).

6. The method according to claim 1, wherein the material bridge (6) has a thickness less than the thickness of the watch component (5).

7. The method according to claim 1, wherein the finishing work includes step h) wafer finishing the front, back and / or side of the watch component (5), and the wafer finishing step comprises depositing a layer.

8. The method according to claim 1, wherein the components of one cluster include a batch of the same components selected from a wheel, cam, needle, lever, snail, vibrating weight, index, or appliqué.

9. The method according to claim 1, wherein the components of one cluster include a batch of different components selected from a wheel, a cam, a needle, a lever, a vibrating weight, a snail, an index, or an appliqué.

10. The method according to claim 7, wherein the deposited layer includes a structural layer and / or a decorative layer.

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