Patent Application
20240036522
This application claims priority of European patent application No. EP22187582.6 filed Jul. 28, 2022, the content of which is hereby incorporated by reference herein in its entirety.
The present invention relates to a method for manufacturing a horological component. It relates also to a horological component as obtained by such a manufacturing method.
Different decoration and/or marking methods are implemented on external part components of a timepiece. With respect to these external part components, a horological movement component is often of smaller dimension, and comprises functional parts of very precise geometry, that must in no circumstances be deteriorated. Thus, it is very difficult to produce a marking on such a horological movement component, for example for the purpose of identification or of decoration.
Thus, the object of the present invention is notably to find a solution for marking and/or decorating a horological component, in particular a horological movement component, which makes it possible to achieve a particularly attractive visual effect without damaging the functionality of the component.
To this end, the invention relies on a method for manufacturing a horological component comprising at least one portion comprising a surface, in particular a top surface, characterized in that it comprises at least the following steps:
The invention is more particularly defined by the claims.
These objects, features and advantages of the present invention will be explained in detail in the following description of particular embodiments given in a nonlimiting manner in relation to the attached figures in which:
The invention implements a method for manufacturing a horological component which advantageously combines at least one engraving step and one step of colouring of said engraving obtained, so as to obtain a visible engraving that does not impact the functional performance of a movement component.
To simplify the reading of the patent application, the same references will be used in the different embodiments and their variants in order to denote the same features. The manufacturing method according to an embodiment of the invention will be illustrated in the context of the manufacturing of a horological movement component, which can for example be a spiral spring.
According to this embodiment illustrated by
The horological component blanks 1a can therefore be manufactured by micro-manufacturing operations from a substrate 10a, which preferably takes the form of a micro-machinable material or is based on micro-machinable material. Note that hereinbelow the term blank will be used in the broad sense, to denote any intermediate element in the method for manufacturing the horological component. Thus, the blank can be a simple substrate made available and not yet engraved, or a substrate that is already partially engraved, for example to define all or part of the outline of the future horological component. To simplify the description, the terms blanks 1a or horological component 1 will alternatively be used to denote the same component, even if the horological component 1 is still being manufactured.
The portion of the blank 1a on which the invention is implemented comprises a surface 11 which will be specifically treated by the method according to the invention, in order to create visible patterns or indications on this surface 11, as will be detailed hereinbelow.
The substrate 10a can be made of a micro-machinable material or be based on a micro-machinable material. The substrate can wholly or partly comprise silicon, in any form. It can thus comprise monocrystalline silicon regardless of its orientation, polycrystalline silicon, amorphous silicon, amorphous silicon dioxide, doped silicon regardless of the type and level of doping. It can notably take the form of a SOI (silicon on insulator) substrate. Alternatively, it can comprise quartz, diamond, glass, ceramic, ruby, sapphire, or silicon carbide. Alternatively, it can be made of metal or of a metal alloy, notably an at least partially amorphous metal alloy. For example, it can comprise nickel or nickel-phosphorus, or even steel, titanium, an alloy of gold, or a platinoid alloy.
Advantageously, the depth of at least one or all of the cavities 7 is less than 10 μm. More advantageously, this depth is preferentially equal to or greater than the thickness of a layer of silicon dioxide 13, which is optional.
According to this preferred embodiment, such a step consisting in engraving E3 by deep reactive ion etching also makes it possible to obtain a bottom 17 whose surface texture is notably characterized by a particularly low roughness, notably with a bottom 17 having a roughness Ra less than 50 nm, preferentially of the order of 20 nm, or less than 20 nm, and/or a roughness Sa less than 100 nm, preferentially of the order of 80 nm, or less than 80 nm, which makes it possible to reveal the flash of the layer of material deposited subsequently on such a bottom 17, as will be explained.
Also, this step consisting in engraving E3 the surface 11 of the horological component 1 is advantageously performed in a same operation as a step consisting in engraving an outline of said horological component 1. As a variant, this step consisting in engraving E3 said surface of the portion of said horological component 1 can be performed before a step consisting in engraving an outline of said horological component 1. In these cases, the method can comprise a step of positioning of a first mask, not represented, on the substrate 10a, notably on said surface 11 of said substrate 10a, so as to perform the step consisting in engraving E3 at least one cavity 7 from this first mask, notably a blind engraving, using the deep reactive ion etching (DRIE) technology, and a step of positioning of a second mask, not represented, on said substrate 10a, notably on another surface of said substrate 10a, so as to engrave an outline of the blank 1a of the horological component 1 from this second mask. In other words, the engraving used to cut the component from the substrate and the engraving forming at least one cavity according to the invention can be performed in one and the same operation, or partially in one and the same operation. These two engravings are performed from different masks.
It can thus be advantageous to use a deep reactive ion etching (DRIE) for a component notably comprising silicon, quartz, glass or diamond.
As a variant, the engraving can comprise the implementation of a laser etching, notably by a femtosecond laser.
The method then comprises, in an embodiment of use of a substrate 10a wholly or partly comprising silicon, an optional step consisting in oxidizing E8 the surface of the blank 1a. As illustrated by
The method then comprises a step consisting in depositing E7 a metal or metal alloy layer 22 on said surface 11 of the blank 1a, both in the at least one cavity 7, more specifically on the bottom 17 of the at least one cavity 7, and outside of the at least one cavity 7.
According to this embodiment illustrated by
This step consisting in depositing E7 the metal or metal alloy layer 22 can be performed by a directional deposition, notably a physical vapour phase deposition (PVD), notably by a deposition by electron beam evaporation (EBE). Thus, advantageously, the metal or metal alloy layer 22 is deposited so as to avoid any deposition of material on the side walls 18 of the cavities 7, which are, here, at right angles or substantially at right angles to the bottom 17. The result of this step is illustrated by
Also, it is found that the sacrificial layer function of this metal or metal alloy layer 22, which will be detailed hereinbelow, is optimal for small thicknesses of this layer, notably a thickness less than or equal to 100 nm.
The method then implements a fourth step consisting in depositing a material E4 on the surface of the component, more specifically on the metal or metal alloy layer 22, at least in the at least one cavity 7 and possibly on the surface 11 outside of the cavity 7. According to the embodiment illustrated by
Preferentially, the material is a metal forming part of the group comprising Au, Ag, Cr, CrN, Ni, Pt, TiN, ZrN, Pd or the alloys thereof, unless incompatible with the metal or metal alloy layer 22. In another variant, this material could not be metallic, as will be specified hereinbelow.
The thickness of this at least one layer of material 8 can be of the order of a few nanometres. It is preferably at least 5 nm, even at least 10 nm, even at least 50 nm, even at least 100 nm. More particularly, it is preferably between 5 nm and 1000 nm, even between 100 nm and 1000 nm. A thickness of between 100 nm and 200 nm forms a good solution, as will be described hereinbelow.
The step of deposition of a material E4 can comprise the deposition of a single and unique layer. Alternatively, this step of deposition can comprise the successive deposition of two or more distinct layers.
According to one embodiment, the material deposition step E4 is performed by a directional deposition, notably by a physical vapour deposition (acronym PVD), notably by electron beam evaporation (EBE). More generally, this deposition can be a vapour phase deposition, such as the abovementioned physical deposition (PVD) or a chemical deposition (CVD) or an atomic deposition (ALD).
Optionally, the material deposition step E4 can comprise a first substep prior to the application of a mask 24, for example a rigid mask or a stencil, such as a mask 24 made of silicon, to reduce the extent of the surface 11 affected by the deposition of the layer of material 8 on the metal or metal alloy layer 22 around the cavity or cavities 7, in order to favour the subsequent step of removal E5 of the metal or metal alloy layer 22, which will be described hereinbelow. According to a first variant, the pattern of the mask 24 can correspond exactly to the patterns of the cavities 7 so as to deposit the material only in the cavities 7. However, according to a second, simpler variant, the pattern of the mask 24 does not need to exactly match the pattern formed by the cavities 7 on the surface 11, and can show a narrow surface area of the surface of the component around the cavities, as represented by
Note that, in
The method then comprises a step consisting in removing E5 the metal or metal alloy layer 22 deposited outside of said at least one cavity, notably by selective chemical attack. Indeed, this step can implement a lift-off of the layer of chromium through a selective chemical attack, in particular through the intermediary of an acid bath. This attack is such that it eliminates the metal or metal alloy layer 22 without damaging the surface 11 of the horological component, notably without damaging the layer of silicon dioxide according to this embodiment. The dissolving of the metal or metal alloy layer 22 at the same time induces the removal of the layer of material 8 situated outside of the cavity or cavities 7. In this step, the fact notably that the layer of material 8 does not totally cover the metal or metal alloy layer 22 over all of the surface 11 of the component makes it possible to minimize the time needed to perform this step. The final result is illustrated by
The metal or metal alloy layer 22 thus fulfils the sacrificial layer function, which allows the easy removal of the layer of material deposited outside of the cavities, the desired end result being to conserve this material only in the cavities.
Advantageously, the perfect covering of the layer of material 8 on the metal or metal alloy layer 22 present in the cavities 7 allows these layers not to be impacted by the removal step E5. Thus, these two layers 22, 8 remain present in the cavities 7. It should be noted that the metal or metal alloy layer 22 advantageously fulfils a second adhesion layer function for the layer of material 8 in the cavities, by improving the adhesion of the layer of material 8 on the component 1.
Moreover, to optimize the removal step described above, it is very advantageous for there to be a discontinuity of the metal or metal alloy layer 22 at the at least one cavity 7. Thus, it is advantageous for there to be no metal or metal alloy layer 22 deposited over all or part of the side walls 18 of the at least one cavity, notably not in the upper part of these side walls 18. In other words, the metal or metal alloy layer 22 extends only over the bottom 17 of the cavity 7 or does not extend over the side walls 18, or extends over a negligible height of the side walls 18, notably not in the upper part of the side walls. To facilitate this result, it is also advantageous for the at least one cavity 7 to itself have a discontinuity at the boundary between the surface 11 and the side walls 18 of the cavity 7. This is notably the case when the side walls 18 are vertical or substantially vertical. In addition, the thickness of the layer of material 8 is thick enough for it to be able to completely cover the metal or metal alloy layer 22 in the cavities 7, notably at least on the bottom 17 of the cavities 7, and to not have holes likely to allow acid to pass through during a chemical attack performed in this removal step. Thus, according to a preferred embodiment, the thickness of the layer of material 8 is at least 100 nm, notably is between 100 and 200 nm. It should be noted that the thickness of the layer of material 8 is preferentially greater than that of the metal or metal alloy layer 22. More generally, any configuration, combining all or part of the features proposed above, making it possible to render the metal or metal alloy layer 22 not accessible inside the at least one cavity 7, is highly advantageous to guarantee the non-removal of the two superposed layers 22, 8 at the at least one cavity.
Finally, the method can comprise an optional step consisting in detaching E6 the blanks 1a from the substrate 10a. To facilitate the implementation of this step, the component blank 1a can comprise a partially engraved break zone, notably as described in the document EP3632839A1.
Naturally, the composition of the metal or metal alloy layer 22 will be adapted on a case-by-case basis to that of the layer of material 8 selected, for example as a function of the material selected and/or the thickness thereof. The metal or metal alloy layer 22 will have a composition different from that of the layer of material 8 in the case where the latter is metal.
According to variant embodiments, the step consisting in depositing E4 a material consists of a step of application on the bottom 17 of the cavity or cavities 7 of a layer of material 8 which is a layer of a paint, applied by any technique known to the person skilled in the art, such as a spraying technique or through the use of a brush. Alternatively, a layer of a lacquer, of a varnish or of a composite material, in particular a luminescent composite material, can be applied.
The thickness of said layer of material 8 can subsequently match the depth of the cavity 7 in which it is deposited. In this particular case, the thickness of said layer of material 8 can preferentially be very slightly less than the depth of the cavity 7.
Note that, in all the embodiments and their variants, it is possible to perform the material deposition step E4 after the implementation of the step consisting in detaching E6 the blank 1a from the substrate 10a, notably in the context of a manual application of the layer of material 8 according to the embodiment described above.
Furthermore, in all the embodiments, all the steps could be implemented on a component blank 1a on its own, not linked to a substrate. They can also be implemented at different steps in the manufacturing of a horological component, that is to say on a blank of such a horological component, or during manufacturing, even directly on a finalized or quasi-finalized horological component.
Such a method is very particularly suited to the manufacturing of a spiral spring, by using the variant consisting in producing the cavity or cavities of the invention before engraving the coils, otherwise it would in practice be difficult to position a liquid resin on turns to engrave the cavities of the invention since the resin would flow between these coils, in the particular case in which the step E3 is a step of deep reactive ion etching.
Finally, it appears that the invention achieves the objects sought through the combination of the following two essential steps applied to at least a portion comprising a surface, in particular a top surface, of a horological component blank or of a horological component:
In all the embodiments and their variants, the depth of at least one cavity, and preferably of all the cavities, is advantageously less than 10 μm, even less than 6 μm. This depth is, in addition, optionally greater than 3 μm. Thus, this depth can be between 3 μm and 10 μm, even between 3 μm and 6 μm. Surprisingly, it appears to the naked eye, for a horological component of small size such as a horological movement component like a spiral spring, that the contrast between at least one cavity 7 and the surface 11 is all the more marked when the depth of said at least one cavity 7 is small. That is all the more notable when the layer of material 8 is metal or a metal alloy and the component notably wholly or partly comprises silicon.
Furthermore, the depth of at least one cavity, and preferably of all the cavities, can also be greater than or equal to the thickness of a possible coating of silicon dioxide 13 present on said surface when the component only or partly comprises silicon. Such a coating of silicon dioxide can have a thickness of between 0.1 μm and 5 μm.
As a variant, particularly suitable if the component 1 is an external part component such as, for example, a bezel disk, in particular made of ceramic, the depth of at least one cavity, and preferably of all the cavities, is between 10 μm and 100 μm, even between 15 μm and 80 μm, even between 20 μm and 50 μm.
In the notable case of a horological movement component, at least one cavity, preferably all the cavities, can also have a length of at least 100 μm, even of at least 150 μm, even of at least 200 μm, even of at least 250 μm, in at least one direction. This length can be less than or equal to 800 μm, even less than or equal to 600 μm, even less than or equal to 500 μm, even less than or equal to 400 μm.
The material deposited in the at least one cavity can be a metal or a metal alloy. As a variant, it can be a paint, a lacquer, a varnish, a composite material, notably a luminescent composite material in particular, with, optionally, an intermediate adhesion metal layer.
In the embodiments and their variants, the material deposited in the at least one cavity advantageously has a thickness strictly less than the depth of the cavity. The deposit thickness can be greater than or equal to 100 nm. It can be between 100 nm and 1000 nm, advantageously between 100 nm and 200 nm. In particular, it can have a thickness equal to or substantially equal to the depth of the cavity. In addition, the sum of the thickness of the layer of material 8 and of the thickness of the metal or metal alloy layer 22 can be strictly less than the depth of the cavity or substantially equal to the depth of the cavity.
The invention applies particularly well to any horological movement component made of a micro-machinable material, that is to say one obtained from micro-manufacturing techniques, particularly those involving photolithography or those involving laser machining. Thus, such a horological movement component, in particular its general form, can for example be obtained, at least partially, by a deep reactive ion etching (acronym DRIE) step. In particular, such a horological movement component, particular its general form, can for example be obtained, at least partially, by UV-Liga (Llthographie Galvanik Abformung) technology.
The horological component according to the invention can wholly or partly comprise silicon, in any form. It can thus comprise monocrystalline silicon, regardless of its orientation, polycrystalline silicon, amorphous silicon, amorphous silicon dioxide, doped silicon regardless of the type and the level of doping. It can notably be manufactured from an SOI (silicon on insulator) substrate.
The horological component according to the invention can also comprise silicon carbide, glass, ceramic, quartz, ruby or even sapphire. Alternatively, it can be made of metal or a metal alloy, notably an at least partially amorphous metal alloy. For example, such a component can comprise nickel or nickel-phosphorus, or even steel, titanium, an alloy of gold, or a platinoid alloy.
Naturally, the invention is not limited to the embodiments described, and it is possible to imagine other embodiments, for example by combining embodiments and/or their variants. In particular, the engraving step E3 can combine the implementation of deep reactive ion etching by using a mask obtained by photolithography and laser etching, notably by a femtosecond laser.
It therefore appears that the invention achieves the objects sought by advantageously combining an engraving on a surface of a component and the partial, even total, filling thereof with a material, via a sacrificial metal or metal alloy layer. This combination makes it possible to form a legible marking, in particular a visible and attractive marking, even on a small surface, without impacting functionality of a horological movement component. Advantageously, this surface is a top surface or a visible surface, notably a surface that is visible when the component is assembled in a timepiece, in particular in a horological movement. Alternatively, this surface is a bottom surface or a non-visible surface.
The marking can be provided for decorative purposes. Alternatively or in addition, it can be provided for identification purposes. The variants of the method according to the invention, which involve a laser, in particular a femtosecond laser, are particularly advantageous in order to individualize the marking on a horological component, in particular a horological movement component, notably a particular spiral spring. The marking can for example form a serial number or a measurement result.
The invention relates also to a horological component obtained by the manufacturing method described previously. The component can be a horological movement component such as a lever, a wheel, for example a wheel of an escapement device, an anchor, a balance or a spiral spring, notably an oscillator spiral spring. As a variant, the horological component can be an external part component such as a bezel or a bezel disk, or a flange.
Notably, according to a particular embodiment, the component can be a horological movement component such as a spiral spring made of a micro-machinable material comprising a first portion forming a link part comprising a surface, in particular a top surface or a visible surface, and a second portion that is less rigid than the first portion comprising at least one blade spiral-wound forming a spring, the surface of the first portion comprising at least one cavity in which is deposited a material according to the invention. More generally, the horological component, or at least the portion comprising the surface affected by the invention, is advantageously based on a micro-machinable material, notably silicon-based, that is to say comprising by weight at least 50% micro-machinable material.
The link part 3 comprises a first, central portion 31 in the form of a portion of a ring arranged around the blade 2, the angular extent of which is of the order of 100 degrees with respect to the axis A1. This link part 3 also comprises two bent portions 32 disposed on either side of the first, central portion 31, each of which comprises an element 5 for positioning and/or fixing said spiral spring, which here takes the form of an opening.
The link part 3 has the particular feature of comprising patterns (or indications) 6 applied to its top surface 11, positioned in the plane P1, notably on its central portion 31. The top surface 11 is, here, formed in continuity with the top surface 12 of the at least one blade 2 of the spiral spring.
The patterns 6 result from the method described previously, and comprise cavities 7 formed from the top surface 11, in which a layer of material 8 is deposited.
The extent e of the patterns, that is to say also the extent of the cavities, measured radially relative to the axis A1, can be greater than 100 μm, even greater than 150 μm, even greater than 200 μm, even greater than 250 μm. Such patterns or indications 6 can thus be visible or legible once the spiral spring 1 is mounted in an assembled balance, which is itself assembled in a horological movement.
This spiral spring can be a spiral spring for a sprung balance. It can be of a single piece. It can be made of silicon, and it can be manufactured from a substrate of silicon or from an SOI (silicon on insulator) substrate. The surface considered by the invention can be covered with a coating of silicon dioxide.
The invention relates also to a timepiece comprising such a horological component. It relates in particular to a horological movement comprising such a horological movement component.
| Number | Date | Country | Kind |
|---|---|---|---|
| 22187582.6 | Jul 2022 | EP | regional |
