Manufacturing method for watch movement parts

Abstract

A method for manufacturing a watch movement part (1) having at least a surface (11), in particular a first part including the top surface, the method comprising at least the steps of engraving (E3) the surface (11) of the watch movement part (1) or of a blank (1a) of a part (1) to form at least one cavity (7) and depositing (E4) material in the at least one cavity (7).

Description

[Technical field]

[0001] The present invention relates to a method for manufacturing a timepiece movement part, and also to the timepiece movement part itself obtained by said method. [Background technology]

[0002] Various decoration and / or marking methods are implemented for external parts of watches. Compared to external parts, watch movement parts are usually small in size and contain functional parts with very precise shapes that must not be changed. For this reason, it is very difficult to create markings for such watch movement parts, for example for identification or decoration purposes. It is noted that in addition to functionality, aesthetic aspects are also very important, especially for watch movement parts. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] European Patent Application Publication No. 3632839 Summary of the Invention [Problem to be solved by the invention]

[0004] The object of the present invention is therefore to find a solution for the marking and / or decoration of watch movement parts, which makes it possible to achieve particularly attractive visual effects, without impairing the functionality of the parts. [Means for solving the problem]

[0005] The invention therefore relates to a method for manufacturing a timepiece movement part, comprising at least a first part comprising a surface, in particular a top surface, the steps of: Etching said surface of said timepiece movement part or of a blank of said part to form at least one cavity, depositing a material into the at least one cavity; The present invention is based on a method for manufacturing a watch movement part, which includes at least the steps of: The etching may advantageously be performed by photolithographic deep reactive ion etching through a mask. The invention also relates to a timepiece movement part which is a hairspring made of a micro-machinable material, comprising a first part forming a connection part including a surface, in particular an upper surface, and a second part having a lower stiffness than the first part, comprising at least one strip wound in the form of a spiral forming a spring, said surface of said first part comprising at least one cavity in which a layer of material is deposited.

[0006] The invention is more particularly defined in the claims.

[0007] The objects, features and advantages of the present invention will be explained in detail in the following description of specific embodiments, given in a non-limiting manner with reference to the accompanying drawings. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 shows the successive steps of a method for manufacturing a timepiece movement hairspring according to a first embodiment of the invention. [Diagram 2] FIG. 2 shows the successive steps of a method for manufacturing a timepiece movement hairspring according to a first embodiment of the invention. [Diagram 3] FIG. 3 shows the successive steps of a method for manufacturing a timepiece movement hairspring according to a first embodiment of the invention. [Figure 4] FIG. 4 shows the successive steps of a method for manufacturing a timepiece movement hairspring according to a first embodiment of the invention. [Diagram 5] FIG. 5 shows the successive steps of a method for manufacturing a timepiece movement hairspring according to a first embodiment of the invention. [Figure 6]FIG. 6 shows the successive steps of a method for manufacturing a timepiece movement hairspring according to a first embodiment of the invention. [Figure 7] FIG. 7 shows a first modification of the first embodiment of the present invention. [Figure 8] FIG. 8 shows a second modification of the first embodiment of the present invention. [Figure 9] FIG. 9 shows a second modification of the first embodiment of the present invention. [Figure 10] FIG. 10 shows a second modification of the first embodiment of the present invention. [Figure 11] FIG. 11 shows a third modification of the first embodiment of the present invention. [Figure 12] FIG. 12 shows a third modification of the first embodiment of the present invention. [Figure 13] FIG. 13 shows a third modification of the first embodiment of the present invention. [Figure 14] FIG. 14 shows the successive steps of a method for manufacturing a timepiece movement hairspring according to a second embodiment of the invention. [Figure 15] FIG. 15 shows the successive steps of a method for manufacturing a timepiece movement hairspring according to a second embodiment of the invention. [Figure 16] FIG. 16 shows a first modification of the second embodiment of the present invention. [Figure 17] FIG. 17 shows a flow chart, which diagrammatically illustrates steps and sub-steps of a method for manufacturing a timepiece movement part according to an embodiment of the present invention. [Figure 18] FIG. 18 is a top view of a hair spring produced by a manufacturing method according to an embodiment of the present invention. [Figure 19] FIG. 19 is a cross-sectional view of the hairspring of FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] The invention implements a method for manufacturing a watch part that advantageously combines a step of etching, at least to a shallow depth, and a step of coloring said etching obtained so as to obtain a visible etching, which does not affect the functional performance of the movement parts.

[0010] To facilitate understanding of this specification, the same reference numbers are used to designate the same features in the various embodiments and their variants.The manufacturing method according to an embodiment of the invention will be described in terms of the manufacture of a watch movement part, which may be, for example, a hairspring.

[0011] 1 to 6 are cross-sectional views of a watch movement part 1, or of a blank 1a of a part, during various steps of production, according to a first embodiment of a method for producing a watch movement part. The inventive method relates to a particular phase of production, in particular to a method for etching a surface. Advantageously, the method is a method for etching a visible or upper surface of the watch movement part 1, in particular for decorative purposes. Alternatively, the method is a method for etching a non-visible or lower surface, in particular for identification or marking purposes. The etching method may be carried out in the final phase of the production of the part, or alternatively in various more or less advanced stages of the method for producing the part.

[0012] According to this embodiment, the method comprises a first step E1 consisting of providing at least a portion of a blank 1a of a watch movement part 1, shown notably in cross section in the various figures illustrating the manufacturing method. It is noted that in this advantageous embodiment, several blanks 1a are connected to the same support or substrate 10a and can be simultaneously subjected to the method described below, the steps of which are summarized in the flow chart of FIG.

[0013] For this purpose, a watch component blank 1a may be produced in advance from a substrate 10a by a micromachining operation, preferably from a micromachinable material such as silicon. It is noted that the term blank is used in a broad sense to designate any intermediate element in the manufacturing process of a watch component. A blank may thus be either the substrate provided and yet to be etched, or a substrate that has already been partially etched, for example to define all or part of the contour of the future watch component.

[0014] The blank 1a portion includes a surface 11, which is specifically treated by the method of the present invention for the purpose of creating a visible pattern or indicia on said surface, as will be described in detail below. The surface 11 is a silicon dioxide (SiO 2 ) substrate in one embodiment using a silicon substrate 10a. 2 The method thus advantageously includes a preliminary step of oxidation of the silicon.

[0015] FIG. 2 shows a first substep E21 of the second step of making the mask E2, consisting of depositing a layer of photosensitive resin 9 on the surface 11 of the blank 1a. The resin may be deposited using any technique known to the person skilled in the art, for example by dip coating, or spray coating, or spin coating. In the example shown, the resin is an acrylic positive resin designed to dissolve in a developer under the action of radiation, while the parts not exposed to radiation remain insoluble or almost insoluble. In this example, the layer of photosensitive resin is more particularly a layer of resin known under the trade name AZ® 9260, the thickness of which is about 6 μm. This substep E21 may be followed by an optional substep of annealing the deposited resin layer 9.

[0016] 3 shows a second substep E22, in which the resin layer 9 is exposed to UV radiation through openings 910 in a mask 91, said openings 910 pre-representing the visible patterns or indicia to be created on the watch movement part, as will be explained in more detail below. The UV radiation in this case is perpendicular to the plane in which the mask 91 extends and perpendicular to the surface 11 of the blank 1a, so as to irradiate only those areas 13 of the resin layer 9 that are present in coincidence with the openings 910 made in the mask 91.

[0017] 4 shows a third substep E23, which consists in removing, by means of a solvent, the irradiated resin in the areas 13 coinciding with the openings 910 of the mask 91. At the end of this substep, the resin layer 9 comprises openings 92 on the surface 11, in a pattern corresponding to the pattern of the openings 910. This resin layer 9 with the openings 92 forms a mask 21, intended for carrying out an etching step which will be described below.

[0018] FIG. 5 shows the implementation of a third etching step E3. In this first embodiment, the etching is carried out with a mask 21, made of resin, which takes the shape of the resin layer 9 deposited on the surface of the component part, as described above. According to this embodiment, the etching is carried out with the deep reactive ion etching (DRIE) technique, which makes it possible to form cavities 7 with vertical or substantially vertical sides, coinciding with the openings 92 in the resin layer 9, without affecting the areas of the surface 11 that remain covered with the resin layer 9. More specifically, the etching step first etches the layer of silicon dioxide present on the surface 11 of the blank 1a, and then etches the silicon, so as to form at least one cavity 7. Each cavity 7 has a substantially rectangular cross section, delimited by a surface forming a bottom 17, substantially parallel to the surface 11 of the component. The depth of the cavities, measured perpendicular to the surface 11, corresponds to the distance between the plane of the surface 11 and the plane of the bottom 17 of the cavity, respectively.

[0019] Advantageously, the depth of at least one or all of the cavities 7 is less than 10 μm and preferably equal to or greater than the thickness of the silicon oxide layer.

[0020] It is noted that said etching step, advantageously carried out by deep reactive ion etching, also makes it possible to reveal the gloss of the layer of material subsequently deposited on the bottom part 17, as will be explained below, and in particular makes it possible to obtain a bottom part 17 with a surface state characterized by a particularly low roughness, in particular a roughness Ra of less than 50 nm, preferably of the order of or less than 20 nm, and / or a roughness Sa of less than 100 nm, preferably of the order of or less than 80 nm.

[0021] The method then performs a fourth step E4 of depositing a material into the at least one cavity 7, as shown in Figure 6. Depending on the embodiment, the material is a metal or metal alloy, and the depositing step forms a layer 8 of metal or metal alloy on the bottom 17 of the cavity 7.

[0022] Preferably, the material is a metal from the group Au, Ag, Cr, CrN, Ni, Pt, TiN, ZrN, Pd, or an alloy thereof.

[0023] The thickness of the at least one material layer 8 may be as little as a few nanometers. The thickness is preferably at least 5 nm, or at least 10 nm, or at least 50 nm, or at least 100 nm. More particularly, the thickness is preferably between 5 nm and 1000 nm, or between 100 nm and 1000 nm.

[0024] The step of material deposition E4 may comprise the deposition of only a single layer, or alternatively, it may comprise the successive deposition of two separate layers, a first layer being deposited directly on the bottom 17, which is intended to act as an adhesion layer for a second layer, e.g. decorative, visible in the cavity 7.

[0025] According to an embodiment, the material deposition step E4 is carried out by physical vapor deposition (PVD). More generally, the deposition may be a vapor deposition method, such as the aforementioned physical vapor deposition (PVD), chemical vapor deposition (CVD) or atomic deposition (ALD). It is noted that in the material deposition step, the mask 21 formed by the resin layer 9 is also used as a mask for this step. This mask 21 makes it possible to protect the unetched surface 11 of the part of the blank 1 in question, while ensuring the deposition of the material on the bottom 17 of the cavity 7. More specifically, the material is deposited on the bottom 17 of the cavity coinciding with the opening 92 of the mask 21, and on the resin 9 resting on the surface 11.

[0026] The method then carries out a fifth step E5 of removing the resin layer 9, which may be carried out, for example, by dissolution with chemicals or by plasma treatment, at the end of which the blank 1a of the watch movement part is ready.

[0027] Finally, the method may comprise a step E6 consisting of detaching the blank 1a from the substrate 10a. To simplify the implementation of said step, the component blank may comprise a partially etched break area, as described in particular in US Pat. No. 5,399,993.

[0028] In variant embodiments, the mask 21 used may be implemented differently than according to the embodiment detailed above.

[0029] Figure 7 illustrates a first variant embodiment, in which the second step E2 of creating a mask for the above-mentioned purposes is based on the use of a laser. Once the photosensitive resin layer 9 has been applied to the surface 11 of the blank 1a, as shown in Figure 2, the method carries out a step of etching using a laser, in particular a laser with femtosecond pulses, the irradiation R of which is predefined according to a selected pattern. In this way, the laser irradiation etches both the resin layer 9, which corresponds to the above-mentioned step E2 of creating a mask, and the top layer 11 of the blank 1a, which corresponds to the above-mentioned etching step E3. The method then continues with the material deposition step E4, as described above.

[0030] Figures 8 to 10 illustrate a second variant embodiment in which the mask 21 used is no longer made of plastic, but in the form of a plate 19 made of a rigid material, for example silicon, which is first deposited on the surface 11 of the component blank 1a, as shown in Figure 8. To enable the removal of the plate 19, an intermediate layer 29 of parylene can also be deposited between the plate 19 and the blank 1a. The method then uses radiation R from a laser, in particular from a femtosecond pulsed laser, which, as in the previous case, forms an opening 92 in the mask 21 and then an etching 7 on the surface 11 of the blank 1a. As in the previous variant, the two steps of generating the mask with the opening 92 E2 and the etching E3 are carried out simultaneously or almost simultaneously in the same etching step. Then, as shown in Figure 10, a material deposition step E4 is carried out in a similar manner to that described above, through the rigid mask 21 at the bottom of the cavity 7.

[0031] Figures 11 to 13 show a third variant embodiment, in which a mask 21 is placed on the surface 11 of the blank 1a after the etching step E3. In particular, as shown in Figure 11, the etching step E3 is performed by means of a femtosecond laser, the radiation R of which directly etches the surface 11 of the blank 1a along a predefined path corresponding to the selected pattern, without the need for a mask.

[0032] After completing the etching and making the etching or etchings 7, the method performs a step E2 of making a mask. This step includes a preliminary step consisting of preparing a mask 21 at a distance from the component blank 1a by making openings 92 on a rigid plate 19 according to a selected pattern. The mask 21 is then placed on the surface 11 of the component blank 1a, as shown in FIG. 12. In this step, the mask 21 is positioned on the blank 1a, using any technique known to the skilled person, in such a way that its openings 92 are precisely superimposed on the prefabricated cavities 7, preferably with an accuracy of the order of microns. To enable the removal of the plate 19, an intermediate layer 29 of parylene may be deposited between the mask 21 and the surface 11 of the blank 1a.

[0033] The method then carries out a material deposition step E4, which is carried out in a similar manner as described above, through the mask 21 onto the bottom of the cavity 7, as shown in Figure 13. In this embodiment, the mask is only used for the material deposition step E4 and is no longer used for the etching step E3.

[0034] In all the above-mentioned embodiments in which a mask is used, the method performs a step E5 of removing the mask after its use.

[0035] 14 to 16 illustrate a second embodiment, which differs from the first in that no mask is used either in the etching step E3 or in the material deposition step E4.

[0036] This second embodiment comprises the same initial steps as the third variant of the first embodiment, up to the making of an etching 7 in the surface 11 of the blank 1a, as shown in FIG.

[0037] The method then carries out a material deposition step E4 using a laser transfer technique known as LIFT (Laser-Induced Forward Transfer). As shown in figures 14 and 15, said technique consists first of all in inserting between the laser device and the component blank 1a a transparent metallized plate 81, which in this embodiment comprises a metal layer 810. Alternatively, a metallized film can be used instead of the metallized plate.

[0038] The laser is then directed at the metallization plate 81 in such a way that the irradiation R from the laser beam on the plate 81 strikes the metal layer 810 and generates a mechanical force on said metal layer 810 sufficient to cause the transfer of material from the metallization plate 81 to the component blank 1a. Of course, the laser irradiation is performed with precision along the pattern generated by the etching or etchings 7 of the blank 1a, which is precisely superimposed on the etching or etchings 7. Thus, the layer of metallic material 8 resulting from the metal layer 810 of the metallization plate 81 is transferred to the bottom 17 of the cavity or cavities 7, as shown in FIG. 15. More specifically, the technique makes it possible to transfer, by means of laser pulses, in particular femtosecond laser pulses, at least a part of the metal layer 810 onto the bottom 17 of the cavity or cavities 7, so as to form a layer of material 8. Preferably, the thickness of said layer of material 8 is at least 100 nm.

[0039] Finally, the method performs the final step of removing the blank or blanks 1a from the substrate 10a.

[0040] Figure 16 illustrates a variant of the second embodiment, in which the material deposition step E4 consists of applying a layer of material 8, which is a layer of paint 80, applied by any technique known to the person skilled in the art, such as a spraying technique or by using a brush, to the bottom 17 of the cavity or cavities 7. Alternatively, a layer of lacquer, varnish or composite material, in particular a luminescent composite material, may be applied.

[0041] The thickness of the layer 8 of material may correspond or substantially correspond to the depth of the cavity 7 in which it is deposited. Preferably, the depth is greater than 10 μm, or greater than 15 μm, or greater than 20 μm.

[0042] It is noted that in all embodiments and their variants, the material deposition step E4 may alternatively be carried out after carrying out the step E6 of detaching the blank 1a from the substrate 10a, in particular in view of the manual application of material 80 as in the embodiment described above.

[0043] Furthermore, in all embodiments, all steps may be performed on a component blank alone, not connected to a substrate, all steps may be performed during different steps of the manufacture of the watch movement part, i.e. on a blank of the watch movement part during manufacture or directly on a finished or nearly finished watch movement part.

[0044] According to another advantageous variant embodiment, the invention may be carried out further upstream of the above-mentioned embodiment, in particular in the same operation or upstream of an etching operation of the blank 1a that serves to define the contour of the future component, in whole or in part. Thus, the method may for example comprise a step of positioning a first mask on the substrate 10a, which serves to perform an etching of at least one cavity, in particular a stop etching, for the purpose of depositing material in the at least one cavity according to the principles of the invention. The method may also comprise a further step of positioning a second mask on the substrate 10a, in particular on the second surface of the substrate 10a, which serves to perform an etching of the contour of the component blank 1a. In other words, the etching used to cut the component from the substrate and the etching forming at least one cavity according to the invention may be carried out in the same operation or partly in the same operation. The two etches are made with different masks.

[0045] This variant of the method is particularly suitable for the manufacture of hair springs, since it is particularly advantageous to create the cavity or cavities of the invention before etching the coil, since otherwise it would be practically difficult to place the resin on the coil in order to etch the cavity of the invention, since the resin would otherwise flow between the coils.

[0046] Finally, the invention is seen to achieve the desired object through the combination of two essential steps, applied to at least a first portion, including a surface, in particular the top surface, of a watch movement part blank or a watch movement part: - E3, etching on the surface of the blank or of the watch movement part to form at least one cavity; - depositing material in said at least one cavity E4.

[0047] In all embodiments and variants thereof, the depth of at least one cavity, and preferably all cavities, is advantageously less than 10 μm, or less than 6 μm. The depth may also optionally be greater than 3 μm. Thus, the depth may be between 3 μm and 10 μm, or between 3 μm and 6 μm. Surprisingly, to the naked eye, the contrast between the at least one cavity 7 and the surface 11 appears more pronounced the shallower the depth of the at least one cavity 7.

[0048] Alternatively, the depth of at least one cavity, and preferably all cavities, is between 10 μm and 100 μm, or between 15 μm and 80 μm, or between 20 μm and 50 μm.

[0049] The depth of at least one cavity, and preferably all cavities, may be equal to or greater than the thickness of the silicon oxide coating present on the surface, such silicon oxide coating may comprise a thickness between 0.5 μm and 5 μm.

[0050] At least one cavity, and preferably all cavities, may have a length in at least one direction of at least 100 μm, or at least 150 μm, or at least 200 μm, or at least 250 μm, which may be no more than 800 μm, or no more than 600 μm, or no more than 500 μm, or no more than 400 μm.

[0051] The material deposited in the at least one cavity may be a metal or a metal alloy, alternatively the material may be a paint, a lacquer, a varnish, a composite material, in particular a luminescent composite material, optionally with an intermediate metallic adhesion layer.

[0052] In both embodiments and their variants, the material deposited in at least one cavity advantageously has a thickness strictly smaller than the depth of the cavity. The deposition thickness may be greater than or equal to 100 nm. The thickness may be between 100 nm and 1000 nm. Alternatively, it may be the same or substantially the same as the thickness of the cavity.

[0053] The invention is particularly applicable to any clock movement part made of a micromachinable material, i.e. obtained by means of a micromachining technique, in particular involving photolithography or involving the use of a laser. To this end, such a clock movement part, in particular its overall shape, may for example be obtained, at least in part, in a deep reactive ion etching (DRIE) step. Alternatively, such a clock movement part, in particular its overall shape, may for example be obtained, at least in part, by a UV-Liga (LIthography Galvanik Abformung) technique.

[0054] The clock movement part according to the invention may comprise silicon in any form, either in whole or in part. Thus, the clock movement part may comprise monocrystalline silicon, regardless of its orientation, polycrystalline silicon, amorphous silicon, amorphous silicon dioxide, doped silicon, regardless of doping type or level, or porous silicon. In particular, the clock movement part may be manufactured from a silicon on insulator (SOI) substrate.

[0055] The watch movement part according to the invention may also comprise silicon carbide, glass, ceramic, quartz, ruby ​​or sapphire. Alternatively, it may be made of a metal or metal alloy, in particular an at least partially amorphous metal alloy. For example, the part may comprise Ni or NiP.

[0056] Of course, the invention is not limited to the described embodiment, and other implementations are also possible, for example by combining the embodiments and / or variants. In particular, the etching step E3 may combine photolithographic deep reactive ion etching with laser etching, in particular with a femtosecond laser. The invention thus appears to achieve the desired object by advantageously combining etching on the surface of the component and filling it partially or completely with material. Said combination makes it possible to form a legible marking, in particular a visible and attractive marking, even on small surfaces, without affecting the functionality of the watch movement component. Advantageously, said surface is an upper or visible surface, in particular a visible surface when the component is assembled in the watch movement. Alternatively, said surface is a lower or non-visible surface.

[0057] The marking may also be intended for decorative purposes. Alternatively or additionally, the marking may be used for identification purposes. The variant of the method according to the invention involving a laser, in particular a femtosecond laser, is particularly advantageous for individualizing the marking on a particular part of a watch movement, in particular on a particular hairspring. The marking may form, for example, a serial number or a measurement result.

[0058] The invention also relates to a timepiece movement part obtained by the manufacturing method described above, which may be a lever, a wheel such as an escapement wheel, an anchor assembly, a balance wheel or a hairspring, in particular an oscillator hairspring.

[0059] In particular, according to one embodiment, the timepiece movement part may be a hairspring made of a micromachinable material, comprising a first part forming a connecting member including a surface, in particular the top or visible surface, and a second part, less rigid than the first part, including at least one spirally wound strip forming the spring, the surface of the first part comprising at least one cavity in which the material according to the invention is deposited. More generally, the timepiece part, or at least the part comprising the surface considered according to the invention, is advantageously based on a micromachinable material, in particular based on silicon, i.e. comprises at least 50% by weight of micromachinable material.

[0060] 18 shows a hair spring obtained by a manufacturing method according to one of the above-mentioned embodiments. The hair spring comprises at least one strip 2, the upper surface 12 of which lies in a plane P1 and the outer end of which is manufactured in one piece with a connecting piece 3 having a stiffness significantly higher than the stiffness of the at least one strip 2. The hair spring 1 further comprises a collet 4 of axis A1, which is manufactured in one piece with the inner end of the at least one strip 2.

[0061] The connecting element 3 comprises a first central portion 31 in the form of a ring portion arranged around the strip 2, the angular extent of which is in the order of 100° relative to the axis A1. The connecting element 3 also comprises two bent portions 32 arranged on either side of the first central portion 31, each of which comprises an element 5 for positioning and / or attaching the hair spring, in this case in the form of an aperture.

[0062] The connecting member 3 has the particular feature of including a pattern (or indicia) 6 applied to an upper surface 11, in particular to its central portion 31, located in the plane P1. The upper surface 11 is in this case formed in continuity with an upper surface 12 of at least one strip 2 of the hairspring.

[0063] The pattern 6 is obtained from the method described above and includes a cavity 7 formed from the upper surface 11 and in which a layer 8 of material has been deposited.

[0064] FIG. 19 shows a cross-section of a central portion 31 of the hairspring connecting member 3 to clearly show the above-mentioned pattern 6 formed by a cavity 7 of depth p, the bottom 17 of which is covered with a layer 8 of material.

[0065] Surprisingly, to the naked eye, the contrast between the pattern 6 and the top surface 11 of the connection member 3 appears to be more pronounced when the cavities 7 have a depth p, measured perpendicular to the plane P1, between the top surface 11 and each of the bottoms 17 of the cavities 7, that is as shallow as possible. Alternatively, the depth may be considered between the top surface 11 and each of the top surfaces of the layers 8 of material that are deposited on the bottoms 17 of the respective cavities 7 and whose thickness is very small.

[0066] In addition, the extent e of the pattern, measured radially to the axis A1, may be greater than 100 μm, or greater than 150 μm, or greater than 200 μm, or greater than 250 μm. Such a pattern or indicia 6 becomes visible or legible when the hairspring 1 is mounted in an assembled balance wheel that is assembled into a timepiece movement.

[0067] The hairspring may be a free balance hairspring. The hairspring may be one piece. The hairspring may be made of silicon. The surface contemplated by the present invention may be covered with a coating of silicon oxide. Alternatively, the hairspring may be made of a silicon on insulator (SOI) substrate.

[0068] The invention also relates to a clock movement comprising such a clock movement part.The invention also relates to a clock comprising at least one such clock movement or one such clock movement part.

Claims

1. A method for manufacturing a timepiece movement part (1), comprising at least a first portion of a surface (11), comprising the steps of: a step (E3) of etching (11) of said surface (11) of said watch movement part (1) or of a blank (1a) of said watch movement part (1) to form at least one cavity (7), said etching being carried out by photolithographic deep reactive ion etching through a mask (21); A step (E4) of depositing material in said at least one cavity (7), The method includes at least the steps of: A method for manufacturing a watch movement part (1).

2. The depth of the at least one cavity (7) is less than 10 μm. The method of claim 1.

3. The depth of the at least one cavity (7) is in the range between 10 μm and 100 μm. The method of claim 1.

4. said at least one cavity (7) extends across said surface (11) over a length of at least 100 μm in at least one direction; The method of claim 1.

5. the first portion including the surface (11) is a micromachinable material; The method of claim 1.

6. the step consisting of etching (E3) the surface (11) of the portion of the clock movement part (1) is carried out in the same operation as the step consisting of etching the contour of the clock movement part (1); and / or the step consisting of etching (E3) the surface of the portion of the clock movement part (1) is carried out before the step consisting of etching the contour of the clock movement part (1), and / or The method is: - positioning a first mask (21) on the substrate (10a) so as to carry out a step consisting of etching (E3) at least one cavity (7) from said first mask (21); positioning the second mask (21) on the substrate (10a) so as to etch the contour of the blank (1a) of the watch movement part (1) from the second mask (21), The method of claim 1.

7. said step consisting of etching (E3) said surface of said part of said watch movement part (1) or of said blank (1a) of said watch movement part (1) further comprises laser etching, The method of claim 1.

8. said step consisting of depositing (E4) said material in said at least one cavity (7) comprises the deposition of a metal, a metal alloy, a paint, a lacquer, a varnish or a composite material; The method of claim 1.

9. said step of depositing (E4) said material in said at least one cavity (7) comprises the deposition of a metal or metal alloy by a vapor deposition method; The method according to claim 8.

10. said step consisting of depositing (E4) said material in said at least one cavity (7) comprises said depositing said material on the bottom (17) of said cavity (7) with a thickness strictly smaller than the depth of said cavity, the thickness of said deposited material being greater than or equal to 5 nm, or said step of depositing (E4) said material in said at least one cavity (7) comprises said depositing said material on a bottom (17) of said cavity (7) with a thickness equal or substantially equal to said depth of said cavity (7); The method of claim 1.

11. Preparation (E1) of a substrate (10a) based on a micro-machinable material, comprising one or more blanks (1a) of the watch movement part (1) to be manufactured, prior to said etching of said surface and said deposition of said material; including the preliminary step of before or after said step consisting of depositing (E4) material in at least one cavity (7) of said surface (11) of at least a first portion of at least one blank (1a) of a watch movement part (1), comprising a step consisting of removing (E6) said at least one blank (1a) of a watch movement part from said substrate (10a), The method of claim 1.

12. The timepiece part is a lever, a gear, an anchor assembly, a balance wheel, or a spring. The method of claim 1.

13. A timepiece movement part (1) manufactured by the manufacturing method according to claim 1, which is a hairspring made of a micro-machinable material, comprising a first part forming a connecting element (3) comprising a surface (11) and a second part less rigid than said first part, comprising at least one strip (2) wound in a spiral forming a spring, said surface (11) of said first part comprising said at least one cavity in which said layer (8) of material is deposited, Clock movement parts (1)

14. An integral balance / hairspring made of silicon covered with a coating of silicon oxide.

14. A clock movement part according to claim 13.

15. the depth of said at least one cavity (7) is less than 10 μm; and / or the depth of the at least one cavity (7) is equal to or greater than the thickness of the silicon oxide coating on the top surface; and / or The length of said at least one cavity (7) is at least 100 μm in at least one direction; 14. A clock movement part according to claim 13.

16. the material deposited in the at least one cavity (7) is a metal, a metal alloy, a paint, a lacquer, a varnish, or a composite material; and / or the material deposited in the at least one cavity has a thickness strictly less than a depth of the cavity, the thickness of the deposited material being greater than or equal to 5 nm or equal to or substantially equal to the depth of the cavity; 14. A clock movement part according to claim 13.

17. The micromachinable material comprising a base of silicon and a silicon oxide coating having a thickness between 0.5 μm and 5 μm. The method according to claim 5.

18. The method of claim 17, wherein the laser etching is performed using a femtosecond laser. The method according to claim 7.

19. The method of claim 19, wherein the step of depositing (E4) a material in the at least one cavity (7) comprises depositing a composite material, the composite material being a luminescent composite material. The method according to claim 8.

20. The method of claim 1, further comprising the step of depositing a connection layer prior to the step of depositing (E4) a material in the at least one cavity (7).

20. The method of claim 19.

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