WO2025186395A1 - Method for manufacturing a timepiece component - Google Patents

Abstract

The invention relates to a method for manufacturing a timepiece component, the method being characterised in that it comprises the following steps: depositing (E1.2) a layer N (30) of photosensitive resin; then exposing (E1.3) the photosensitive resin of the layer N (30) with exposure radiation (55) according to a first predefined pattern, defining at least one portion (32) of photosensitive resin of the non-exposed layer N (30); depositing (E1.4) an optical filter layer (35) directly on all or part of the layer N (30) of undeveloped photosensitive resin, in particular an optical filter layer (35) integrally deposited in the same plane; depositing (E1.5) a layer N+1 (40) of photosensitive resin directly and/or indirectly on the layer N (30) of photosensitive resin, in particular directly and/or indirectly on the optical filter layer, and optionally in contact with a flank of the layer N (30); exposing (E1.6) the photosensitive resin of the layer N+1 (40) of photosensitive resin with exposure radiation (65) according to a second predefined pattern defining at least one portion (42) of photosensitive resin of the layer N+1 (40) of unexposed photosensitive resin; developing (E1.7.1) the layer N (30) of photosensitive resin and developing (E1.7.2) the layer N+1 (40) of photosensitive resin, so as to remove a portion of photosensitive resin from each layer N, N+1 (30, 40) of photosensitive resin defined by the first and second predefined patterns, respectively, for the exposure, forming a mould delimited at least partially by the remaining photosensitive resin, at least one portion of resin of the layer N (30) being removed to form a cavity (11) under a portion of resin of the layer N+1 (40) of photosensitive resin which is not removed, forming a portion of the layer N+1 (40) of photosensitive resin comprising at least partially the layer of the optical filter (35) on the lower surface thereof and being arranged cantilevered over the cavity (11) of the layer N (30).

Description

Manufacturing process of a watch component

The present invention relates to a method of manufacturing a mold for manufacturing a watch component. It also relates to a method of manufacturing a watch component which uses such a mold. It also relates to a mold for manufacturing a watch component as such, obtained by such a method.

Existing manufacturing processes for watch components are poorly or not at all suitable for the manufacture of a component with complex geometry, i.e., in particular one with a complex three-dimensional shape. These processes sometimes manage to achieve certain complex geometries, but through tedious steps such as post-machining, and/or to the detriment of the resolution of the geometry, which leads to a lack of precision in the shapes obtained. Generally speaking, existing manufacturing processes for watch components therefore do not allow all complex shapes to be manufactured with sufficient precision.

Thus, the object of the present invention is to improve the known methods of manufacturing a watch component, and in particular to be able to manufacture a watch component of complex shape in a simple manner and with great precision.

To this end, the invention is based on a method of manufacturing a mold for the manufacture of a watch component, characterized in that it comprises the following steps:

Deposit an N layer of photosensitive resin; then

Insolating said photosensitive resin of the N layer with insolation radiation according to a first predefined pattern, defining at least a portion of photosensitive resin of the non-insulated N layer; Depositing an optical filter layer directly on all or part of the undeveloped N layer of photosensitive resin, in particular an optical filter layer fully deposited in the same plane; Depositing an N+1 layer of photosensitive resin directly and/or indirectly on the N layer of photosensitive resin, in particular directly and/or indirectly on said optical filter layer, and possibly in contact with a side of the N layer;

Insolating said photosensitive resin of the N+1 layer of photosensitive resin with insolation radiation according to a second predefined pattern defining at least a portion of photosensitive resin of the N+1 layer of non-insulated photosensitive resin;

Developing the N layer of photosensitive resin and developing the N+1 layer of photosensitive resin, so as to remove a part of photosensitive resin from each N, N+1 layer of photosensitive resin defined respectively by said first and second predefined patterns for exposure by forming a mold delimited at least partially by said remaining photosensitive resin, at least a part of resin of the N layer being removed to form a cavity under a part of resin of the N+1 layer of photosensitive resin which is not removed, forming a part of the N+1 layer of photosensitive resin at least partially comprising the layer of said optical filter on its lower surface and being arranged in a cantilever manner on said cavity of the N layer.

The invention also relates to a method of manufacturing a watch component, characterized in that it comprises a first step corresponding to the method of manufacturing a mold as described above, and a second step of forming the watch component comprising a step consisting of filling all or part of said mold with a material of the component.

The invention also relates to a mold for the manufacture of a watch component, characterized in that it comprises a layer N of photosensitive resin forming at least a first cavity of the mold and an N+1 layer of photosensitive resin forming at least a second cavity of the mold, this second cavity being superimposed on the first cavity, and the N+1 layer of photosensitive resin comprising a portion overhanging above the first cavity of the N layer, the lower surface of this portion being at least partially covered by an optical filter layer.

The invention is more particularly defined by the claims.

These objects, characteristics and advantages of the present invention will be explained in detail in the following description of particular embodiments made without limitation in relation to the attached figures among which:

Figure 1 represents a sectional view of a mold during a sub-step of a method of manufacturing this mold for a watch component according to a first variant of the first embodiment of the invention.

Figure 2 represents a sectional view of a mold obtained by the manufacturing method according to the first variant of the first embodiment of the invention.

Figure 3 represents a sectional view of the mold obtained by a manufacturing method according to a second variant of the first embodiment of the invention.

Figure 4 schematically represents the sub-steps of the method of manufacturing a mold for a watch component according to the variants of the first embodiment of the invention.

Figure 5 represents a sectional view of a mold during a sub-step of a method of manufacturing this mold for a watch component according to a second embodiment of the invention. Figure 6 represents a sectional view of the mold for a watch component obtained according to the second embodiment of the invention.

Figures 7 to 11 represent sectional views of a mold during the sub-steps of a method of manufacturing this mold for a watch component according to a first variant of a third embodiment of the invention.

Figure 12 represents a sectional view of the mold for a watch component obtained according to the first variant of the third embodiment of the invention.

Figures 13 and 14 represent sectional views of a mold during the sub-steps of a method of manufacturing this mold for a watch component according to a second variant of the third embodiment of the invention.

Figure 15 schematically illustrates the sub-steps of the method of manufacturing a mold according to the invention.

Figure 16 schematically illustrates the sub-steps of the manufacturing process of a watch component from a mold according to the invention.

The invention achieves the desired objects by the intermediate manufacture of a particular mold, which may have a complex shape, in particular having a cantilevered structure, which will be explained later, in order to obtain a watch component of complex shape by a simple molding in this particular mold. A complex shape is notably achieved by the use of a multi-level mold, that is to say, having the form of a structure formed by several layers superimposed in a certain stacking direction, each layer forming a part of the mold cavity. By convention, we will consider the adjectives "upper" and "lower" in relation to this stacking direction, the first positioned elements being lower and below the elements subsequently deposited above, which will be higher than them. The invention first relates to a method of manufacturing a mold for manufacturing a watch component, as shown schematically in Figures 1 to 15. It then relates to a method of manufacturing a watch component as such, the first step E1 of which consists of implementing said method of manufacturing a mold, and the second step E2 of which consists of using such a mold to manufacture a watch component as such, as shown schematically in Figure 16.

For ease of reading, the same references will be used for the different embodiments and the different variants of the invention to designate identical or very similar characteristics.

We will first describe the method of manufacturing a mold for the manufacture of a watch component according to particular embodiments chosen as illustrative examples. This method therefore forms a first step E1 before the subsequent manufacture of a watch component, and we will describe below the sub-steps of this first step E1.

The invention will be illustrated on the basis of two superimposed photosensitive resin layers, which can be integrated into a structure comprising a multitude of layers: for this reason, these layers will be called N and N+1 layers. To simplify the figures, only these two N, N+1 layers will be shown, and positioned directly on the substrate. Naturally, the invention is not limited to a mold formed by only two photosensitive resin layers, but applies to any number of layers greater than or equal to two. Moreover, the concept of the invention can be implemented on any pair of successive resin layers, and on any number of pairs of successive resin layers among all the superimposed layers. In other words, the concept of the invention can be implemented at least at any two successive N, N+1 resin layers, and at most at all pairs of two successive resin layers. Figures 1 and 2 illustrate a method of manufacturing a mold for a watch component according to a first variant of a first embodiment of the invention.

Figure 1 illustrates a multilayer structure obtained after implementing different sub-steps detailed below. This structure comprises a stack on a substrate 20 comprising a first layer N 30 of photosensitive resin, insolated, covered over its entire upper surface by a lower layer of optical filter 35, itself covered by a conductive layer 36, covered by an upper layer of optical filter 37. Then, a second layer N+1 40 of photosensitive resin is placed on the layer N, indirectly, since it is located on the upper layer of optical filter 37. Figure 1 illustrates more precisely the sub-step of insolation E1.6 of the layer N+1 40 of photosensitive resin. The sub-steps of manufacturing this structure are detailed below.

First, the method comprises a first sub-step E1.1 consisting of providing a substrate 20 which is in a substantially flat shape of small thickness, comprising an upper surface 21. The substrate 20 may be in the form of a wafer. This substrate 20 may be in an electrically conductive material, such as a metal or a metal alloy, such as stainless steel. Alternatively, it may be in a semiconductor material, such as silicon, or in a non-conductive material, for example ceramic. In the latter cases, it may be advantageous to coat the upper surface 21 with a conductive layer, for example by thermal evaporation; this conductive layer may optionally be in the form of a multilayer structure, for example an underlayer of chromium, nickel or titanium covered with a layer of gold or copper. The function of such a conductive property of the upper surface 21 of the substrate 20 is to be able to participate in the initiation of a mold filling process by electroforming for example, as will be detailed later. The upper surface 21 of the substrate 20 is generally flat, and may be polished, or alternatively may comprise positive or negative relief patterns, in particular machined patterns, and/or cavities, and/or other structures, for example produced by microfabrication. The substrate 20 may be provided with markers, so that it can be positioned very precisely during the various steps. It may be prepared in any known manner, in particular for its degreasing, its cleaning, possibly its passivation and/or its activation.

In all cases, the substrate 20 fulfills the function of support for the manufacture of the mold which will be formed by a stack of several layers of photosensitive resin superimposed on the upper surface 21 of the substrate, according to the photolithography technology, an integral part of the LIGA process (abbreviation for "Lithography, Galvanoformung, Abformung"). The substrate 20 is thus covered with several layers of photosensitive resin, each layer being intended to ultimately form a part of the mold.

The method comprises a second method substep consisting of depositing E1.2 a layer N 30 of photosensitive resin on the surface 21 of the substrate 20, or alternatively on another layer N-1, as explained previously. The resin is deposited according to known methods. The resin used can be deposited in liquid phase, or alternatively, in solid phase: it is then called “dry” resin. In the case of a liquid resin, the deposition can for example be carried out by “spin-coating” (also called “rotational deposition” or “centrifugal coating” or “centrifugal coating”) or by “spray-coating” (also called “spray deposition” or “spray coating”). In the case of a dry resin, the deposition can for example be carried out by a rolling or pressing process.

A third sub-step of the process consisting of exposing E1.3 said photosensitive resin of the N layer 30. Indeed, the photosensitive resin is suitable for photolithography. This resin can be negative or positive. In the first In the case of a negative resin, it is designed to become insoluble or difficult to dissolve in a developer under the action of insolation radiation, that is to say that the areas exposed to a certain radiation called insolation will resist development, as will be detailed later. In the second case of a positive resin, the resin is on the contrary designed to become soluble in a developer under the action of insolation radiation, while the part not exposed to the radiation remains insoluble or difficult to dissolve. In all the examples and illustrations which follow, the resin used is of the "SU-8" type, and is a negative photosensitive resin, which polymerizes under the action of UV (ultraviolet) radiation, such as for example the SU-8-100 resin from the company Kayaku Advanced Materials. In all embodiments, this negative resin could be replaced by a positive resin, and the insolation radiation, the masks, and the different layers of the stack will then be adapted to this type of resin.

For this step consisting of exposing E1.3 said photosensitive resin of the layer N 30, not shown, the layer N 30 of photosensitive resin is subjected to exposure radiation through a mask, comprising openings allowing the exposure radiation to pass through, which thus reaches parts of the layer N 30 of photosensitive resin. The mask further comprises at least one zone opaque to the exposure radiation, which does not allow the exposure radiation to pass through. The mask corresponds to a first predefined pattern, and defines at least one part 32 of non-exposed photosensitive resin and at least one part 31 of exposed resin. As a note, to obtain an equivalent result with a positive resin, the mask used would be reversed, so that the part(s) 31 exposed with a negative resin would not be exposed with a positive resin, whereas the part(s) 32 not exposed with a negative resin would be exposed with a positive resin. At the end of this exposure sub-step E1.3, the layer N 30 of photosensitive resin is said to be “exposed”, and therefore comprises one or more exposed parts 31 and one or more non-exposed parts 32. As a note, the exposed layer according to the invention therefore corresponds to a layer of resin comprising exposed resin and non-exposed resin. This sub-step is very similar to the sub-step consisting of exposing E1.6 a layer N+1 40 of photosensitive resin, shown more specifically in figure 1, and which will be described below.

The method of manufacturing a mold then comprises a sub-step consisting of depositing E1.4 a lower layer of optical filter 35 directly on all or part of the upper surface of the layer N 30 of exposed photosensitive resin.

In this embodiment, the lower optical filter layer 35 fulfills the optical function of filtering the wavelengths which insolate the photosensitive resin of the N layer. It thus avoids any subsequent parasitic insolation of the photosensitive resin, which would involuntarily modify the insolation defined by the sub-step E1.3 described previously, and which would ultimately induce a modification of the precision of the geometry of the mold during manufacture. Preferably, the lower optical filter layer 35 makes it possible to attenuate more than 98%, or even more than 99%, or even more than 99.9% of such insolation radiation.

The optical filter layer may be an antireflective layer and/or an absorbing layer. It may be deposited by various methods, for example spin-coating (also called spin-coating), spray-coating (also called spray-coating), dip-coating, chemical vapor deposition (CVD), physical vapor deposition (PVD), atomic layer deposition (ALD), pulsed laser ablation deposition (PLD), or by rolling or pressing processes. It may comprise a material of an organic nature. In particular, it may be a layer of the material known by its trade name AZ®-BARLi® II.

According to the embodiment, the optical filter layer 35 is deposited on the entire upper surface of the photosensitive resin layer N. This approach is advantageous because it is simple to implement. Alternatively, it may only be deposited on certain parts of the N layer, in particular at the level of the resin zones which must not be exposed, to protect them. In this case, it may be locally etched, to remove a part of the optical filter layer 35 previously added over the entire surface of the N layer. Alternatively, the optical filter layer 35 may be deposited selectively. In the case of the embodiment described, the optical filter layer 35 could cover at least the parts 32 not exposed with photosensitive resin of the N layer 30.

Advantageously, the lower optical filter layer 35 is entirely deposited in the same plane. Here, it is a plane parallel to the plane of the upper surface 21 of the substrate 20. It is deposited on the N layer 30 of undeveloped photosensitive resin.

The method then comprises a sub-step consisting of depositing E1.c a conductive layer 36, at least on all or part of the lower optical filter layer 35. As will be detailed later, it is advantageous to form a mold which comprises conductive surfaces, in particular for its subsequent filling by electroplating, according to LIGA technology.

According to this embodiment, the deposition of the conductive layer 36 is carried out by physical vapor deposition (PVD). This conductive layer 36 may be made of a metal, or a metal alloy. Advantageously, it may be made of gold.

In this deposition sub-step E1.c, the lower optical filter layer 35 makes it possible to filter the wavelengths emitted during this deposition, for example by a PVD deposition, which would be likely to insolate the photosensitive resin of the N layer of photosensitive resin, and therefore to untimely modify the insolation defined by the predefined insolation pattern, thereby ultimately degrading the future geometry of the mold. The lower optical filter layer 35 therefore prevents any parasitic insolation of the photosensitive resin of the N layer, particularly the part(s) 32 of non-insulated photosensitive resin, during the deposition of the conductive layer.

According to the embodiment, the conductive filter layer 36 is deposited over the entire surface of the N layer 30 of photosensitive resin, indirectly since it is superimposed on the optical filter layer 35. This approach is advantageous because it is simple to implement. Alternatively, it may only be deposited on certain specific parts of the N layer, as will be illustrated in the embodiment variant in relation to FIG. 3. In this case, it may be locally etched, to remove a part of the conductive layer 36 previously added over the entire surface of the N layer. Alternatively, the conductive layer 36 may be deposited selectively, using a mask, for example by the so-called “shadow mask” technique. Advantageously, it is at least deposited on surfaces parallel to the plane of the substrate which will form surfaces of the cavity of the future mold, that is to say surfaces intended for direct contact with the material of the component which will be deposited in the mold cavity.

Additionally, the method comprises a sub-step E1.4 consisting of depositing an upper optical filter layer 37, ultimately forming a sandwich structure, comprising a conductive layer 36 disposed between two optical filter layers 35, 37. Note that the two optical filter layers 35, 37 may be identical or different.

The upper optical filter layer 37 fulfills a function of protecting the N+1 layer 40 of photosensitive resin, to prevent its parasitic insolation. In particular, this upper optical filter layer 37 is particularly useful during the insolation operation E1.6 of the N+1 layer 40 of photosensitive resin, which will be described in more detail later. Indeed, during this step, illustrated in FIG. 1, the insolation radiation 65 intended for the insolation of the N+1 layer 40 would risk being reflected on the conductive layer 36 and reaching parts 42 of resin of the N+1 layer 40 which should not be insolated. The method then implements a sub-step consisting of depositing E1.5 a layer N+1 40 of photosensitive resin on the layer N. In this embodiment, this deposition is indirect on the layer N since the two layers N, N+1 are separated by the lower optical filter layer 35, the conductive layer 36, and the lower optical filter layer 37, which extend over the entire upper surface of the layer N. This deposition of photosensitive resin of the layer N+1 is carried out by any known method, in particular the methods mentioned above for the deposition of the layer N.

The method then implements a sub-step consisting of exposing E1.6 the photosensitive resin of the N+1 layer, as represented by FIG. 1. The N+1 layer 40 of photosensitive resin is subjected to exposure radiation 65 through a mask 55, comprising openings 56 allowing the exposure radiation 65 to pass through, which thus reaches parts 41 of the N+1 layer 40 of photosensitive resin. The mask 55 further comprises opaque zones 57 to the exposure radiation which do not allow the radiation to pass through. The mask 55 corresponds to a second predefined pattern, and defines at least one part 42 of non-exposed photosensitive resin. At the end of this exposure sub-step E1.6, the N+1 layer 40 of photosensitive resin is said to be “exposed”, and therefore comprises one or more parts 41 of exposed resin and one or more parts 42 of non-exposed resin. These two sub-steps E1.5 and E1.6 are very similar to the sub-steps E1.2 and E1.3 relating to the N layer.

In the embodiment illustrated by FIG. 1, the mask 55 extends in a plane parallel to the surface 21 of the substrate 20, and the insolation radiation 65 is perpendicular to the plane in which the mask 55 extends, so as to irradiate only the parts 41 of the photosensitive resin located at right angles to the openings 56 provided in the mask. Alternatively, the insolation radiation could be inclined relative to the plane in which the mask extends and/or that of the upper surface 21 of the substrate 20. As a further variant, not illustrated, a mask with transmittance variation can also be used so as to form flanks inclined in the resin, or even a surface structuring of the different levels of resin. These characteristics also apply to the mask used for the exposure of the N 30 layer of photosensitive resin.

The exposure radiation used to irradiate or expose the photosensitive resin layers is UV radiation in the case of SU-8 resin. X-rays, electrons, or any other type of exposure radiation suitable for the resin used can be used. In addition, these exposure sub-steps E1.3, E1.6 optionally include a heat treatment sub-step for crosslinking the resin.

As a note, the second pattern defined by the second mask 55 applied to the N+1 layer is consistent with the first pattern defined by the first mask applied to the N layer, so as to obtain at least partially superimposed insolated and/or non-insolated parts, to finally form a mold. Indeed, the method then implements a sub-step consisting of developing E1.7.1 the photosensitive resin of the N and N+1 layers. In this sub-step, a portion of resin is dissolved to form a cavity in each layer of resin, so as to reveal the structure of the mold. In the case of the embodiment where the photosensitive resin is negative, the development consists of eliminating (/.e. deleting, removing, etching) the non-insolated resin parts 32, 42. Alternatively, if the photosensitive resin is positive, the development consists of eliminating the insolated resin areas.

The development method is known to those skilled in the art and is adapted to the resin used. It can be done by dissolving the resin chemically, using suitable solvents and being carried out by spraying solvents or by immersion in them. Alternatively, the development can use a plasma process. A specificity of this embodiment comes from the fact that the development acts through the conductive layer 36 and the optical filter layers 35, 37 to allow the development of the N layer 30 of photosensitive resin on which these layers 35, 36, 37 are deposited. In the case of development by chemical dissolution of the resin, the spraying method of applying the solvents can have sufficient mechanical action on the structure of the layers 35, 36, 37 to damage them so that the solvents can reach the photosensitive resin of the N layer 30 on which they are deposited. The immersion method of applying the solvents is nevertheless preferred from an industrial point of view due to its simplicity of implementation. Immersion alone may prove insufficient for the passage of the solvents through the intermediate layers, which would then be removed by lifting (or "lift-off"). Alternatively, a conventional photolithography step followed by etching can be implemented to make openings in the layers 35, 36, 37 and thus facilitate the passage of the solvents to the lower N layer 30. As a further variant, during immersion in the solvents, ultrasound is applied to break the layers 35, 36, 37 and facilitate access of the solvents to the photosensitive resin of the lower N layer. As a further variant, the same effect could be obtained by stirring the baths or by using megasounds. This solution therefore makes it possible to implement the development of the two superimposed layers N, N+1 of photosensitive resin, whether they are immediately juxtaposed (in direct contact), or separated by the intermediate layers 35, 36, 37. In addition, this development is simultaneous for the two layers N, N+1, that is to say is carried out in the same resin dissolution operation. This development can therefore be done chemically by immersion, which is industrially favorable, while optimizing the yield thanks to the variants of assistance by ultrasound (according to a broad definition, i.e. a pressure wave of frequency equal to or greater than 20 kHz, and of frequency equal to or less than 200 kHz) and others mentioned above.

Figure 2 illustrates the mold 10 obtained after simultaneous development E1.7.1, E1.7.2 of the two layers N, N+1 of photosensitive resin. By simultaneous, we mean that the two layers are developed in the same operation. This mold 10 comprises a first cavity 11 obtained within the first layer N 30 of photosensitive resin, and a second cavity 12 partially superimposed obtained within the second layer N+1 40. As described previously, these two cavities 11, 12 are respectively obtained by masks corresponding respectively to first and second predefined patterns. A particularity of the mold 10 according to this second embodiment comes from the fact that the layer N+1 40 of photosensitive resin comprises at least one flank 14 of a cavity 12 superimposed above a cavity 11 of the layer N 30 of photosensitive resin, in particular a flank 14 located at the right of a cavity 11). The resin of the layer N+1 40 thus comprises a cantilevered portion, above the void (above the cavity 11). As a remark, to produce such a cantilevered structure, it is possible to use a particularly advantageous approach, based on a self-supporting dry film of resin, as described by the document EP3748437A1. To optimize such a structure with overhang, it is preferred to develop the N 30 layer of resin as late as possible, therefore in the same operation as that of the resin of the N+1 40 layer. In this way, the overhanging zone of resin of the N+1 40 layer remains supported by the N 30 layer of resin for as long as possible, limiting the risk of its deformation.

The mold 10 according to this embodiment, represented by FIG. 2, therefore comprises two particular cavities 11, 12 forming a cantilevered structure, explained previously. In addition, in this first embodiment, an additional sub-step is implemented, consisting of etching the portion of the upper optical filter layer 37 which is located inside the cavity 12 formed at the level of the N+1 layer 40 of photosensitive resin, thus positioning the conductive layer 36 at the bottom of this cavity, to fulfill its function which will be detailed later when using the mold to manufacture a watch component.

Figure 3 illustrates a mold 10 substantially equivalent to that described previously, according to a second variant of the first embodiment. This second variant is distinguished from the first variant described above by the fact that the different intermediate layers between the two layers N, N+1 of photosensitive resin, that is to say the optical filter layers 35, 37 and the conductive layer 36 do not extend over the entire surface of the N layer 30 of photosensitive resin, but are strategically positioned on the areas where their function is particularly desired. Thus, the lower optical filter layer 35 is only deposited on the N layer of photosensitive resin at the level of the future cavities 11, 12 of the N layer and the N+1 layer. More precisely, it comprises its deposition only on the surface of the N layer 30 of photosensitive resin intended to form a cavity 11 by the removal of the photosensitive resin and the bottom of a cavity 12. As a further variant, this deposition of the optical filter layer can be done only on the surface of the N layer 30 of photosensitive resin intended both to form a cavity 11 while being covered by a portion of resin of the N+1 layer 40 of photosensitive resin intended not to be removed, at a cantilevered arrangement on said cavity 11. Furthermore, the conductive layer 36 is only deposited at the level of the future cavities 12 of the N+1 layer 40, to cover a portion of the bottom of these cavities. This conductive layer 36 thus occupies a smaller surface area than that of the optical filter layer 35, since it is not located, for example, under the overhanging zone of the N+1 layer 40 of photosensitive resin. The upper optical filter layer has been etched and removed, which means that it has completely disappeared from the resulting mold 10.

Figure 4 schematically summarizes the sub-steps of the method of manufacturing a mold according to the variants of the first embodiment of the invention, as detailed previously.

It therefore appears in the preceding embodiments that a combination of a conductive layer and two optical filter layers is particularly suitable for many molds for manufacturing watch components, as will be specified later. The conductive layer, included between two optical filter layers, makes it possible to form an intermediate zone between two layers N, N+1 of a multi-level resin mold, by combining the complementary effects of the three intermediate layers 35, 36, 37 in an optimal manner. However, the invention is not limited to the embodiments described above. For example, unlike the variants described above, the two layers N, N+1 of photosensitive resin could be developed in two separate sub-steps E1.7.1, E1.7.2, the layer N 30 of photosensitive resin being exposed and developed before the deposition of the layer N+1 40 of photosensitive resin. This approach could be implemented alternatively on all the embodiments described.

Naturally, the invention is not limited to the variant embodiments of the first embodiment. Many other mold geometries are possible, depending on the watch component to be manufactured. The use of a single layer of optical filter, as will be illustrated below, with or without a conductive layer, can also improve the production of a mold for manufacturing a watch component. Thus, in other embodiments, the intermediate zone between layers N, N+1 can be modified into a single layer of optical filter with optionally a conductive layer.

Figures 5 and 6 represent sectional views of the manufacture of a mold for a watch component according to a second embodiment of the invention.

Figure 5 illustrates the multilayer structure obtained after implementing different sub-steps similar to those detailed in the first embodiment, and which will not be detailed again. This structure comprises a stack on a substrate 20 comprising a first layer N 30 of photosensitive resin, exposed, covered over its entire upper surface by a single optical filter layer 35. This optical filter layer 35 therefore extends entirely in the same plane, as in all the illustrated variants. This plane is advantageously parallel to the upper surface of the substrate 20. It is positioned on the layer N 30 of exposed and undeveloped resin N. Then, a second layer N+1 40 of photosensitive resin is placed on the layer N, indirectly, since it is located on the optical filter layer 35. Figure 5 illustrates more precisely the sub-step E1.6 of exposure of the layer N+1 40 of photosensitive resin. In this second embodiment, it appears that a part of the exposed parts 41 of the N+1 layer 40 of resin are positioned in line with non-exposed parts 32 of the N layer 30 of resin, which must therefore not be exposed.

The optical filter layer 35 fulfills a function of protecting the N 30 layer of photosensitive resin in this sub-step E1.6, to prevent its parasitic insolation. Indeed, during this sub-step, the insolation radiation 65 intended for the insolation of the N+1 layer 40 would risk reaching the non-insulated part 32 of the N 30 layer of resin at the level of future so-called overhanging zones of the mold, inducing its parasitic insolation and then the degradation of the final geometry of the mold. This risk is particularly linked to the so-called overhanging structure since a part of photosensitive resin of the N+1 layer 40 must be insolated, while being superimposed on a part 32 of the N 30 layer of photosensitive resin which must not be insolated.

Figure 6 illustrates the mold 10 obtained after simultaneous development E1.7.1, E1.7.2 of the two layers N, N+1 of photosensitive resin. This mold 10 comprises a first cavity 11 obtained within the first layer N 30 of photosensitive resin, and a second partially superimposed cavity 12 obtained within the second layer N+1 40. As described previously, these two cavities are respectively obtained by masks corresponding respectively to first and second predefined patterns. A particularity of the mold according to this second embodiment comes from the fact that the layer N+1 40 of photosensitive resin comprises at least one flank 14 of a cavity 12 superimposed above a cavity 11 of the layer N 30 of photosensitive resin, in particular a flank 14 located at right angles to a cavity 11. The resin of the layer N+1 thus comprises a cantilevered portion, above the void. As a note, to produce such a cantilevered structure, it is possible to use a particularly advantageous approach, based on a self-supporting dry film of resin, as described by document EP3748437A1, as previously recalled. In this second embodiment, it therefore appears that the mold comprises as intermediate zone between the two layers of resin a single layer of optical filter 35, unlike the sandwich structure zone illustrated in relation to figures 1 to 3.

As explained above, the embodiment of the invention has been presented on the basis of a two-layer resin mold, in a simplified manner. Naturally, the principle of the invention can be applied to form any structure with several resin layers, the number of which can be greater than two. In addition, the intermediate layer(s), consisting of one or more optical filter layers and/or one or more conductive layers, can have different configurations.

Figures 7 to 12 thus illustrate a first variant of a third embodiment of the invention in which a mold comprises three layers of resin, which will be called N-1 15, N 30 and N+1 40, these three layers being capable of being combined with other upper and/or lower resin layers.

Thus, figure 7 represents the result obtained after exposure and development of a layer N-1 15 of resin, deposited on a substrate 20.

Figure 8 represents a sub-step E1.2 of depositing a layer N 30 of resin, on the layer N-1 15. In this embodiment, the layer N 30 of photosensitive resin also extends partly against the sides of the resin of the layer N-1 and partly on the substrate 20.

Figure 9 shows a sub-step E1.4 of depositing an optical filter layer 35 on only a portion of the upper surface of the resin layer N 30. More specifically, the optical filter layer 35 is not applied to a peripheral surface of the resin layer N 30. This resin layer N 30 remains completely unexposed at this stage, which means that the exposure sub-step E1.3 is not carried out before this deposition sub-step E1.4. Figure 10 represents a sub-step E1.5 of depositing a layer N+1 40 of photosensitive resin on the layer N 30, indirectly at the level of the optical filter layer 35 and directly on the layer N at the level of its peripheral part.

Figure 11 represents the sub-step E1.6 of insolation of the N+1 layer 40 of resin. In this sub-step, the optical filter layer 35 prevents parasitic insolation of the resin of the N layer 30, except in its peripheral zone where insolation is desired. Thus, this variant embodiment simultaneously carries out the sub-step E1.3 of insolation of the N layer 30 and the sub-step E1.6 of insolation of the N+1 layer 40, that is to say in the same operation, with a single insolation radiation 65. As a remark, the sub-step E1.3 of insolation of the N layer 30 is carried out after the sub-step E1.4 of deposition of the optical filter layer 35, unlike the embodiments described previously. It is therefore understood that in all embodiments, the two sub-steps E1.3 and E1.4 can be carried out in any order, depending on the desired mold geometry. In addition, the optical filter layer 35 fulfills the function of a mask with respect to the layer N 30 during this sub-step consisting of exposing E1.3 this first layer N 30.

Figure 12 represents the mold 10 obtained after the development sub-step E1.7.1, E1.7.2 in the same operation of the two layers N 30, N+1 40 of photosensitive resin. This mold 12 comprises a large part of the layer N+1 40 positioned cantilevered above the void.

Figure 13 illustrates a second variant of the third embodiment, which differs more particularly by an alternative of the sub-step consisting of exposing E1.3, E1.6 the two layers N, N+1 of resin, using an upper layer of optical filter 37 arranged on the N+1 layer 40, precisely on the part 42 which must not be exposed. The upper layer of optical filter 37 therefore fulfills here a function different from those explained previously, since it replaces the conventional mask 65 illustrated on the figure 11. A development sub-step E1.7.1, E1.7.2, implemented after this exposure sub-step E1.3, E1.6 then makes it possible to obtain a mold identical to that represented by figure 12.

As a note, in all the exposure steps of all the embodiments of this invention, or even more generally in any solution requiring exposure of a resin, an optical filter layer may be arranged on the resin layer to fulfill the function of a mask during exposure, replacing a traditional mask. Thus, an invention may relate to any method comprising a step of exposure of a resin layer in which an optical filter layer is arranged on said resin layer to fulfill the function of a mask. The optical filter layer having served as a mask may then be retained or may be removed.

Figure 14 represents a third variant of the third embodiment, which implements an additional step E1.c of depositing a conductive layer 36 on the mold 10 obtained by one of the two variants explained above. This conductive layer 36 can be deposited by any technique explained previously, in particular by the PVD deposition of a metal or a metal alloy. The flow of material used to constitute the conductive layer 36 is symbolized by “hollow dotted” arrows. In an advantageous embodiment, the cavity 12 formed in the N+1 layer 40 of resin corresponds to the dimensions of the resin of the N-1 layer 15, which means that the N+1 layer 40 of resin serves as a mask for the deposition of the conductive layer 36, which is deposited precisely and exactly only on the upper surface of the N-1 layer 15, and not on its sides 17 for example. In a particular embodiment, the format of the mold is therefore advantageously chosen to fulfill a second function of masking a conductive layer deposit.

Figure 15 schematically illustrates the sub-steps of the method for manufacturing a mold according to the invention, as detailed previously. We can note that there are several optional sub-steps, represented in lines dotted line. In addition, the order of some sub-steps (e.g. E1.3 and E1.4) may be reversed, as explained above. The representation therefore does not correspond to a mandatory chronological order.

In all embodiments and their variants, the development sub-step is adapted to the resin used, and may be based on a dissolution of the resin by chemical means, using appropriate solvents and being implemented by spraying solvents or by immersion in them, in a manner known to the person skilled in the art. However, the presence of an intermediate zone between two layers N, N+1, or at least on the N layer, or even on the N+1 layer, to be developed in the same operation, or not, by the same chemical means, complicates access to the N layer located under the intermediate zone, or even to the N+1 layer if it is located under an optical filter type layer. In other words, this intermediate zone forms a barrier for the passage of the chemical solution to the resin layer that it covers. Thus, to assist this sub-stage of development, in all embodiments and their variants, ultrasound can be applied to break the intermediate layers and facilitate access of the solvents to the photosensitive resin of the lower N layer, or even to access the N+1 layer. We understand ultrasound to be a broad definition, i.e. a pressure wave with a frequency equal to or greater than 20 kHz, and less than or equal to 200 kHz. As a variant or complement, the agitation of the baths or the use of megasounds could be implemented. This solution therefore makes it possible to implement the development of the two superimposed N, N+1 layers of photosensitive resin, or at least of the lower N layer, or even of the N+1 layer. This development can therefore be done chemically by immersion, which is industrially favorable, while optimizing the yield thanks to the ultrasonic assistance variants and others mentioned above.

Naturally, the invention is not limited to the embodiments described, which can in particular be combined with each other. The invention also relates to a mold for manufacturing a watch component as such, characterized in that it comprises a layer N of photosensitive resin forming at least a first cavity of the mold and a layer N+1 of photosensitive resin forming at least a second cavity of the mold, this second cavity being superimposed on the first cavity, and the layer N+1 of photosensitive resin comprising a portion overhanging above the cavity of the layer N, the lower surface of this portion being at least partially covered by an optical filter layer.

Finally, it appears that the invention uses at least one optical filter layer to manufacture a complex mold for a watch component having a cantilevered structure. In several embodiments, this optical filter layer extends entirely in a plane, which is advantageous because it is simple to implement. In addition, this optical filter layer can also extend over the entire surface of a photosensitive resin layer, which is also advantageous because it is simple to implement. Alternatively, it can extend over only a portion of this layer. In addition, this optical filter layer always fulfills the function of preventing parasitic exposure of the photosensitive resin, but can act for this purpose in a different manner depending on the configurations, as described previously:

- It can be combined with a conductive layer, so as to prevent this conductive layer from inducing parasitic insolation, by reflection and/or by its simple deposition; and/or

- It can be used to protect a layer of resin from exposure when an upper layer is exposed; and/or

- It can be used to protect a layer of resin from exposure at the time of its own exposure, thus replacing all or part of a traditional mask.

The existence of stray insolation radiation is relatively predictable since it depends on the geometry of the chosen configuration. Thus, preferably, as soon as there is a risk of stray insolation radiation, the method according to the invention is implemented, as described above, to thereby eliminate in whole or in part the occurrence of such stray insolation radiation, and thus guarantee the precise formation of a mold. It appears that a risk of stray insolation exists even in a simple situation of insolation radiation perpendicular to the substrate, and with superimposed layers of resin comprising upper and/or lower surfaces parallel to the substrate, that is to say in a priori simple angular geometries. Indeed, as described above, despite this approach, the sheer complexity of the geometry of the different superimposed layers, due to the relative positioning of their insolated and non-insolated parts, and due to the optional presence of metal layers, can induce risks of stray insolation.

The invention also relates to a method for manufacturing a watch component as such, the first step E1 of which consists of implementing the method for manufacturing a mold as described above. Such a type of mold is multi-layer, as described above. Each layer comprises one or more cavities, and the joining of these cavities, which communicate with each other, forms a larger cavity, the mold cavity, the overall geometry of which corresponds to that of the watch component to be manufactured. The second step E2 of the manufacturing method is based on the use of such a mold to manufacture a watch component 1 as such.

An embodiment of this second step E2 will now be described in detail. The second step E2 comprises a first substep consisting of filling E2.1 all or part of the mold with a material, which we will call the component material.

According to a first embodiment variant, this sub-step consists of filling E2.1 the mold by electrodeposition, electroforming, or electroplating. It then makes it possible to produce a metal component. The material of the component can then be a metal or a metal alloy such as, for example, gold, nickel, copper, or nickel-phosphorus (NiP). This sub-step is preferably extended until the entire height of the mold cavity is filled, which has the advantage of allowing the continuous growth of a metal or alloy, in the same filling operation.

In this first embodiment variant, it is necessary for the mold to be at least partly made of conductive material, to act as an electrode for priming, with a view to future metallic growth of the watch component in the mold. Thus, if the substrate is not made of conductive material, such a conductive layer is added to the substrate in the first step of manufacturing the mold, as described previously, in the case where a part of the upper surface 21 of the substrate 20 forms a bottom of the mold.

On the other hand, at least one conductive layer 36 can be advantageously used, as described previously in the manufacture of the mold, to likewise fulfill an electrical conductor function during the growth of the metal in such a mold, as illustrated by the embodiments of figures 2, 3 and 14.

According to a second embodiment, the mold can be used to cast a component material during the filling sub-step E2.1. For example, it is possible to cast slip in order to obtain a technical ceramic watch component. According to another embodiment, it is possible to cast or shape a composite material or metallic glass in the mold. According to another embodiment, it is possible to thermoform a material in the mold.

Optionally, an insert can be placed in the mold cavity, so that it is surrounded by the component material when filling the mold.

Step E2 then includes an optional sub-step E2.2 of thicknessing the watch component, for example by simultaneous mechanical polishing of the metallic layer resulting from galvanic growth, or more generally from the filling material, and the resin mold, to obtain a flat, horizontal upper surface.

The method then includes a sub-step consisting of detaching (in other words unmolding) the watch component from the mold obtained by the previous step.

To do this, the method comprises, for example, a sub-step E2.3 consisting of detaching the watch component and the resin from the mold of the substrate 20, for example by delamination of the conductive layer which coats the substrate.

The method comprises another sub-step consisting of detaching E2.4 the watch component from its resin mold. In this sub-step, the resin forming all or part of the mold is dissolved. This dissolution can be carried out by any means known to those skilled in the art, such as chemical dissolution, the use of the DRIE reactive ion etching technique, plasma etching, or laser ablation.

The order of sub-steps E2.3 and E2.4 can be reversed.

It is clear from the method described above that the entire surface of the watch component formed in direct contact with the mold according to the invention has a perfect final shape upon demolding, without the need for any additional operation. The invention thus makes it possible to very simply manufacture a watch component comprising a complex shape.

Optionally, a finishing step may be implemented on the face opposite the bottom of the mold, which is not formed directly by the mold obtained by the method according to the invention. This finishing step may consist of polishing or grinding this opposite face of the watch component, for example to ensure its flatness. In addition or as a variant, this finishing step may consist of modifying the color or the tribological properties of at least one part of the surface of the watch component by depositing a coating formed by a physical vapor deposition PVD process, or chemical vapor deposition CVD, or atomic layer deposition ALD, or pulsed laser ablation deposition PLD. As a note, this finishing step consisting of coating and/or decorating and/or machining and/or coloring and/or polishing and/or grinding can be applied to the opposite face of the watch component not directly in contact with the mold. In this case, it can therefore be carried out before or after sub-steps E2.3, E2.4 consisting of detaching the watch component from the mold. Alternatively, the finishing step, particularly a coloring step, can be applied to the face of the watch component formed directly in contact with the mold, or even to the entire watch component.

Figure 16 schematically summarizes the sub-steps of step E2 of the manufacturing process of a watch component.

According to one embodiment, the material of the watch component is a metal or a metal alloy, in particular based on nickel or gold or copper. According to another embodiment, the material of the component may be based on ceramic, that is to say comprise all or part of ceramic, advantageously at least 50% by weight of ceramic. According to another embodiment, the material of the component may be a composite material. The resulting watch component is thus mainly made of metal or a metal alloy, for example based on nickel or gold or copper, or is mainly made of ceramic, or is made of a composite material.

The method for manufacturing a watch component as described above is suitable for the manufacture of a multitude of different watch components. For example, the watch component may be a watch exterior component such as an applique or a hand, or a movement component, such as an escape wheel or an anchor or even a spring. According to an alternative embodiment, the watch component may comprise one or more inserts, aesthetic or functional. For this, the manufacturing method may comprise an intermediate step consisting of placing at least one insert in the manufacturing mold, before the step of filling the mold with the material of the component, involving the securing of this material of the component with the at least one insert. Such an insert may be, in a non-limiting manner, a decorative precious stone, a watch axis, or a watch ruby.

In particular, the invention makes it possible to manufacture a watch component which is characterized by the fact that it is mainly in a single-piece form, and even in a single piece, since the watch component can be formed by filling the mold in a single operation of filling the entire mold, unlike, for example, a solution which would consist of filling the mold layer by layer in separate operations, in which case there would be potential fragility at the interfaces between each layer.

The resulting watch component is therefore advantageously a single piece, with the exception of a possible insert. The resulting watch component is therefore advantageously homogeneous. Alternatively, the watch component or timepiece may consist of at least two separate associated parts, at least one part of which is produced using the manufacturing method according to the invention. The watch component may thus have mutually parallel flat surfaces and flanks perpendicular to these flat surfaces, without an inclined surface.

The invention also relates to a timepiece which comprises at least one timepiece component according to the invention.

Claims

1. Method of manufacturing a mold for the manufacture of a watch component, characterized in that it comprises the following steps: Deposit (E1.2) a layer N (30) of photosensitive resin; then Insolate (E1.3) said photosensitive resin of the layer N (30) with insolation radiation (55) according to a first predefined pattern, defining at least a portion (32) of photosensitive resin of the non-insulated layer N (30); Depositing (E1.4) an optical filter layer (35) directly on all or part of the N layer (30) of undeveloped photosensitive resin, in particular an optical filter layer (35) entirely deposited in the same plane; Deposit (E1.5) an N+1 layer (40) of photosensitive resin directly and/or indirectly on the N layer (30) of photosensitive resin, in particular directly and/or indirectly on said optical filter layer, and possibly in contact with a side of the N layer (30); Insolating (E1.6) said photosensitive resin of the N+1 layer (40) of photosensitive resin with insolation radiation (65) according to a second predefined pattern defining at least a portion (42) of photosensitive resin of the N+1 layer (40) of non-insulated photosensitive resin; Developing (E1.7.1) the N layer (30) of photosensitive resin and developing (E1.7.2) the N+1 layer (40) of photosensitive resin, so as to remove a portion of photosensitive resin from each N, N+1 layer (30, 40) of photosensitive resin defined respectively by said first and second predefined patterns for exposure by forming a mold delimited at least partially by said remaining photosensitive resin, at least a portion of resin from the N layer (30) being removed to form a cavity (11) under a portion of resin of the N+1 layer (40) of photosensitive resin which is not removed, forming a part of the N+1 layer (40) of photosensitive resin at least partially comprising the layer of said optical filter (35) on its lower surface and being arranged in a cantilever manner on said cavity (11) of the N layer (30). 2. Method for manufacturing a mold according to the preceding claim, characterized in that the step of depositing (E1.4) an optical filter layer comprises its deposition only on the surface of the N layer (30) of photosensitive resin intended to form said cavity (11) or in that the step of depositing (E1.4) an optical filter layer comprises its deposition only on the surface of the N layer (30) of photosensitive resin intended both to form said cavity (11) and to be covered by a resin portion of the N+1 layer (40) of photosensitive resin intended not to be removed, at said cantilevered arrangement on said cavity (11). 3. Method for manufacturing a mold according to one of the preceding claims, characterized in that said two predefined patterns are such that the development (E1.7.1 and E1.7.2) of said two layers N, N+1 (30, 40) of photosensitive resin forms at least one second cavity (12) in the layer N+1 (40) of photosensitive resin, this second cavity (12) being totally or partially superimposed on the first cavity (11) of the layer N (30) of photosensitive resin. 4. Method for manufacturing a mold according to one of the preceding claims, characterized in that it comprises a subsequent step consisting of depositing (E1.c) a metal layer at least on a part of the surface of the N layer (30) or of a lower layer of photosensitive resin, the N+1 layer (40) of photosensitive resin forming a mask during this step of depositing this metal layer. 5. Method for manufacturing a mold according to one of the preceding claims, characterized in that it further comprises the following step before the step consisting of depositing (E1. 5) a layer N+1 (40) of photosensitive resin: Depositing (E1.c) a conductive layer (36) at least on all or part of the optical filter layer (35), this optical filter layer (35) preventing any parasitic exposure of said part of photosensitive resin of the N layer (30) of non-exposed photosensitive resin during the deposition of the conductive layer (36). 6. Method for manufacturing a mold according to claim 4 or 5, characterized in that the step(s) consisting of depositing (E1.c) a conductive layer (36) is carried out by physical vapor deposition (PVD), and possibly in that the optical filter layer (35) makes it possible to filter the wavelengths emitted during this deposition by PVD and likely to expose the photosensitive resin of the N layer (30) of photosensitive resin. 7. Method for manufacturing a mold according to one of claims 4 to 6, characterized in that it further comprises the following step before the step consisting of depositing a layer N+1 (40) of photosensitive resin (E1.5): Deposit (E1.4) an upper layer of optical filter (37) on all or part of the conductive layer (36). 8. Method for manufacturing a mold according to one of the preceding claims, characterized in that it comprises a preliminary step consisting of providing (E1.1) a substrate (20) then a step consisting of depositing a stack of several layers of photosensitive resin superimposed on the upper surface of the substrate, this stack comprising at least said two layers N, N+1 (30, 40) of photosensitive resin, the substrate (20) forming a bottom of the mold after development of the layers of resin. 9. Method of manufacturing a mold according to one of the preceding claims, characterized in that it comprises a development (E1.7.1) of the layer N of photosensitive resin through the optical filter layer (35) and optionally through the conductive layer (36) and optionally through the upper optical filter layer (37). 10. Method for manufacturing a mold according to the preceding claim, characterized in that the step consisting of developing (E1.7.1) the N layer (30) of photosensitive resin and/or developing (E1.7.2) the N+1 layer (40) of photosensitive resin is carried out chemically and comprises a step of using ultrasound. 11. Method for manufacturing a mold according to one of the preceding claims, characterized in that the step of exposing (E1.3, E1.6) said resin layer (30, 40) uses an optical filter layer arranged on said resin layer (30, 40) to fulfill the mask function. 12. Method for manufacturing a watch component, characterized in that it comprises a first step (E1) corresponding to the method for manufacturing a mold according to one of the preceding claims, and a second step (E2) of forming the watch component comprising a step consisting of filling (E2.1) all or part of said mold with a material of the component. 13. Method for manufacturing a watch component according to the preceding claim, characterized in that the step consisting of filling (E2.1) the mold comprises a single step of filling the entire mold to form a single-piece component. 14. Method for manufacturing a watch component according to one of claims 12 or 13, characterized in that it comprises a step consisting of detaching (E2.3, E2.4) from the mold the watch component obtained by the step consisting of filling (E2.1) the mold, and optionally comprises a finishing step consisting of polishing and/or grinding and/or machining and/or decorating and/or coating and/or coloring at least one side of the watch component, in particular to ensure its height and/or its flatness and/or its decoration. 15. Method for manufacturing a watch component according to one of claims 12 to 14, characterized in that said material of the component is a metal or a metal alloy, in particular based on nickel or gold or copper, or is based on ceramic, in particular based on zirconia, or based on alumina, or based on strontium aluminate, or is based on a cermet, or is a composite material, in particular a material based on polymer and ceramic, such as Hyceram®. 16. Method for manufacturing a watch component according to one of claims 12 to 15, characterized in that the watch component is a watch exterior component such as an applique/index, in particular a godet-shaped applique, or a hand, or a movement component, such as an escape wheel or an anchor or a spring or a nail/rivet, and/or in that the watch component has mutually parallel flat surfaces and flanks perpendicular to these flat surfaces. 17. Mold (10) for the manufacture of a watch component, characterized in that it comprises a layer N (30) of photosensitive resin forming at least a first cavity (11) of the mold and a layer N+1 (40) of photosensitive resin forming at least a second cavity (12) of the mold, this second cavity (12) being superimposed on the first cavity (11), and the layer N+1 (40) of photosensitive resin comprising a portion overhanging above the first cavity (11) of the layer N (30), the lower surface of this portion being at least partially covered by an optical filter layer (35).