EP4303668A1 - Verfahren zur bestimmung der steifigkeit einer spiralfeder - Google Patents

Verfahren zur bestimmung der steifigkeit einer spiralfeder Download PDF

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Publication number
EP4303668A1
EP4303668A1 EP22183023.5A EP22183023A EP4303668A1 EP 4303668 A1 EP4303668 A1 EP 4303668A1 EP 22183023 A EP22183023 A EP 22183023A EP 4303668 A1 EP4303668 A1 EP 4303668A1
Authority
EP
European Patent Office
Prior art keywords
hairspring
blank
plate
installation
openings
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
EP22183023.5A
Other languages
English (en)
French (fr)
Inventor
Johannes Clivaz
Kevin SOOBBARAYEN
David Gachet
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Sigatec Sa
Richemont International SA
Original Assignee
Sigatec Sa
Richemont International SA
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Sigatec Sa, Richemont International SA filed Critical Sigatec Sa
Priority to EP22183023.5A priority Critical patent/EP4303668A1/de
Publication of EP4303668A1 publication Critical patent/EP4303668A1/de
Pending legal-status Critical Current

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Classifications

    • G—PHYSICS
    • G04—HOROLOGY
    • G04D—APPARATUS OR TOOLS SPECIALLY DESIGNED FOR MAKING OR MAINTAINING CLOCKS OR WATCHES
    • G04D7/00—Measuring, counting, calibrating, testing or regulating apparatus
    • G04D7/10—Measuring, counting, calibrating, testing or regulating apparatus for hairsprings of balances
    • G—PHYSICS
    • G04—HOROLOGY
    • G04B—MECHANICALLY-DRIVEN CLOCKS OR WATCHES; MECHANICAL PARTS OF CLOCKS OR WATCHES IN GENERAL; TIME PIECES USING THE POSITION OF THE SUN, MOON OR STARS
    • G04B17/00—Mechanisms for stabilising frequency
    • G04B17/04—Oscillators acting by spring tension
    • G04B17/06—Oscillators with hairsprings, e.g. balance
    • G04B17/066—Manufacture of the spiral spring

Definitions

  • the present invention relates to the field of control and manufacturing of parts for watchmaking. It relates more particularly to a device for determining the stiffness of a balance spring or a balance spring blank based on silicon attached to a wafer based on silicon, by applying a vibrational excitation and by measuring the vibration response of the spiral or blank.
  • the movements of mechanical watches are regulated by means of a mechanical regulator comprising a resonator, that is to say an elastically deformable component whose oscillations determine the running of the watch.
  • a mechanical regulator comprising a resonator, that is to say an elastically deformable component whose oscillations determine the running of the watch.
  • Many watches include, for example, a regulator comprising a hairspring as a resonator, mounted on the axis of a balance wheel and set into oscillation thanks to an escapement.
  • the natural frequency of the balance-spring couple makes it possible to regulate the watch and depends in particular on the stiffness of the balance-spring.
  • silicon spirals can be manufactured on a single wafer using micro-manufacturing technologies. It is particularly known to produce a plurality of silicon resonators with very high precision using photolithography and machining/etching processes in a silicon wafer.
  • the methods for producing these mechanical resonators generally use monocrystalline silicon wafers, but wafers made of other materials can also be used, for example polycrystalline or amorphous silicon, other semiconductor materials, glass, ceramic , carbon, carbon nanotubes or one composite comprising these materials.
  • monocrystalline silicon belongs to the cubic crystal class m3m whose thermal expansion coefficient (alpha) is isotropic.
  • Silicon has a very negative value of the first thermoelastic coefficient, and consequently, the stiffness of a silicon resonator, and therefore its natural frequency, varies greatly depending on the temperature.
  • the documents EP1422436 , EP2215531 And WO2016128694 describe a spiral type mechanical resonator made from a core (or two cores in the case of WO2016128694 ) in monocrystalline silicon and whose temperature variations in Young's modulus are compensated by a layer of amorphous silicon oxide (SiO 2 ) surrounding the core (or cores), the latter being one of the rare materials having a thermoelastic coefficient positive.
  • SiO 2 amorphous silicon oxide
  • the final functional yield will be given by the number of hairsprings whose stiffness corresponds to the pairing interval, divided by the total number of hairsprings. spirals on the plate.
  • SOI Silicon On Insulator
  • simple wafers can be used.
  • the silicon layer called the handle layer which serves as mechanical support, is dissolved to release the so-called device layer, in which the hairsprings are engraved.
  • the excitation and vibration measurement can therefore be carried out on spirals formed in a layer of silicon whose thickness is of the order of 120 ⁇ m. At such a thickness, the rigidity of the wafer or the silicon layer is low, so that the hairsprings neighboring a hairspring on which a measurement is carried out can also be excited and their own vibration can disrupt the vibration response. of the hairspring concerned.
  • the present invention aims to propose a device/equipment making it possible to respond at least partially to the aforementioned problem, and to improve the responses obtained.
  • the invention also relates to a control method implementing a step of using a device according to the invention or the like.
  • the installation makes it possible to isolate at least partially, at the vibration level, the hairspring/the hairspring blank from the rest of the plate, to dampen the parasitic vibrations coming from the hairsprings neighboring the hairspring to be measured and to limit the vibrations of the entire plate by reducing the deformability in bending in particular of the assembly thus constituted by the plate and the installation.
  • the vibration response given by the hairspring is cleaner, that is to say that the spectrum characterizing the vibration response is then no longer/less noisy by parasitic vibrations. Consequently, the observed peaks can be directly and solely attributed to the resonances of the measured hairspring.
  • the peaks of the spectrum that we observe are better defined, allowing better quality exploitation of the results. Thus, by surrounding, we must understand surrounding the hairspring or the blank individually.
  • the vibration excitation source is arranged on a first side of the wafer, and the means for measuring the vibration response are arranged on a second side of the wafer, opposite the first side.
  • the excitation can be better centered and closer to the hairspring.
  • the measuring means can be positioned optimally.
  • the installation comprises a network of openings, intended to be opposite the hairsprings or the hairspring blanks to be measured, the openings being dimensioned so as to allow the vibrations of the hairsprings or the hairspring blanks to be free.
  • This network of openings makes it possible to isolate a plurality of hairsprings or blanks, which can be measured one after the other in an easy manner.
  • holding means can be provided to press the installation and the plate against each other, in order to improve the vibration isolation of the hairspring to be measured.
  • the installation is associated with a clamping plate, the plate being intended to be sandwiched between the installation and the clamping plate.
  • the installation and the clamping plate can each comprise a network of openings, the openings of the installation and the openings of the clamping plate being arranged facing each other and intended to be facing the hairsprings or hairspring blanks to be measured, the openings being dimensioned so as to allow free vibrations of the hairsprings or hairspring blanks to be measured.
  • FIG. 1A we have represented in the following Figures 1A to 1F , certain steps of a process for producing a spiral in a wafer 10 also called wafer, of the SOI (“silicon on insulator”) type.
  • the latter comprises a substrate or "handler” 20 carrying a sacrificial layer of silicon oxide (SiO 2 ) 30 and a layer of monocrystalline silicon 40.
  • the substrate 20 can have a thickness of 500 ⁇ m
  • the sacrificial layer 30 may have a thickness of 2 ⁇ m
  • silicon layer 40 may have a thickness of 120 ⁇ m.
  • the monocrystalline silicon layer 40 can have any crystalline orientation.
  • lithography we mean all the operations making it possible to transfer an image or pattern on or above the wafer 10 to the latter.
  • the layer 40 is covered with a protective layer 50, for example made of a polymerizable resin.
  • This layer 50 is structured, typically by a photolithography step using an ultraviolet light source as well as, for example, a photo mask (or another type of exposure mask) or a stepper and reticle system. This structuring by lithography forms the patterns for the plurality of resonators in layer 50, as illustrated in Figure 1C .
  • the patterns are machined, in particular engraved, to form the plurality of resonators 100 in the layer 40.
  • the etching can be carried out by a deep reactive ion etching technique (also known by the acronym DRIE for “Deep Reactive Ion Etching”). . After etching, the remaining part of the protective layer 50 is subsequently eliminated.
  • the resonators are released from the substrate 20 by locally removing the sacrificial layer 30 or even by etching all or part of the silicon from the substrate or handler 20. Smoothing (not illustrated) of the etched surfaces can also take place before the release step, for example example by a thermal oxidation step followed by a deoxidation step, consisting for example of wet etching based on hydrofluoric acid (HF).
  • HF hydrofluoric acid
  • the turns 110 of the silicon resonator 100 are covered with a layer 120 of silicon oxide (SiO2), typically by a thermal oxidation step to produce a thermo-compensated resonator.
  • This layer 120 which generally has a thickness of 2-5 ⁇ m, also affects the final stiffness of the resonator and therefore must be taken into account during the previous steps to obtain vibrational characteristics of the hairspring leading to obtaining a particular natural frequency of the hairspring-balance couple in a given watch mechanism.
  • the different resonators formed in the wafer generally have a significant geometric dispersion between them and therefore a significant dispersion between their stiffnesses, notwithstanding that the stages of formation of the patterns and the machining/engraving through these patterns are the same for all resonators.
  • the resonators obtained in step 1E on the wafer 10 in question can be deliberately formed with dimensions d which are different from the necessary dimensions (for example greater) to obtain a nominal or target stiffness.
  • a control method intended to estimate the vibration characteristics of the resonators (natural frequency and/or resonant frequencies) to deduce the stiffness and/or the real dimensions of the resonators 100 to correct their dimensions. , which will lead to obtaining the natural frequency of the desired resonator - balance wheel couple.
  • the neighboring hairsprings/hairspring blanks can also, to lesser degrees, undergo excitation, either by receiving the excitation indirectly. sound excitation, or by diffusion of vibration through the plate. This is all the more sensitive when the wafer essentially only contains the device layer during this step or when the spirals are made in a simple wafer, the thickness of which is typically around 120 ⁇ m.
  • the invention proposes to implement a mounting 200 intended to provide support at least on a portion of the wafer or the silicon layer surrounding the hairspring or the blank of the hairspring to be measured.
  • the installation 200 includes an opening 202 leaving the vibrations of the hairspring or the blank free. In other words, the opening is at least slightly larger than the engraving made in the plate to form the hairspring.
  • the support provided by the installation is intended to at least partially isolate, at the vibration level, the hairspring/the hairspring blank from the rest of the plate.
  • the plate being light, its own weight may not be sufficient to generate support to sufficiently isolate the hairspring from disruptive vibrations.
  • We can therefore provide holding means to press the installation and the plate against each other. These means can be of different natures, such as screwing, supporting a weight, or other variants which will be described below.
  • the installation 200 is associated with a clamping plate 300, the plate 10 being intended to be sandwiched between the installation 200 and the clamping plate 300.
  • the installation and the clamping plate each comprise a network of openings, the openings 202 of the installation 200 and the openings 302 of the clamping plate 300 being arranged facing each other and intended to be facing the spirals or the blanks of hairsprings to measure.
  • the openings 202, 302 are dimensioned so as to leave the vibrations of the hairsprings free.
  • a system for assembling and/or tightening the clamping plate 300 against the installation 200 and, if necessary, indexing means 350 of one relative to the other, in order to align the openings.
  • indexing means 350 of one relative to the other, in order to align the openings.
  • pins which pass through the installation 200, the plate 10 and the clamping plate 300 in defined positions.
  • flange systems 400 screwing or other, to stiffen the whole.
  • the clamping means can be distributed around the installation 200 and the clamping plate 300, or be supplemented by clamping means distributed over the surface of the installation and the clamping plate.
  • indexing means can be provided to index the installation 200, the plate 10 and the clamping plate 300, for example with pins or the like secured to the installation or the clamping plate and which pass through the plate to position themselves, respectively, in the clamping plate or in the installation. It is also possible to provide second separate indexing means, to position, on the one hand, the installation 200 and the plate 10, and on the other hand, the clamping plate 300 and the plate 10.
  • the indexing means can be provided even if there is no clamping plate.
  • indexing makes it possible to precisely position the installation 200 relative to the plate 10 and the hairsprings, which makes it possible to position the excitation source 210 and the measuring means 220 in a repeatable manner, of a plate to another. The reliability of the measurement is thus improved.
  • the surfaces of the mounting and, where applicable, of the clamping plate are flat, or even ground, in order to provide well-distributed support all around the hairspring and avoid stress on the plate.
  • the clamping plate and/or mounting can be metallic or even silicon.
  • the attraction means comprise a suction circuit 420 opening into contact with the plate 10, to suck the latter.
  • This suction circuit can be connected to a vacuum generator, by a connector 422, to create a vacuum and suck the plate 10 against the installation 200.
  • the suction circuit can be distributed over the installation 200, for example by offering channels arranged radially around the center of the installation. The latter is intended to be aligned with the center of the wafer, which, in the example, does not include spirals to allow suction of the wafer.
  • the attraction means comprise an electrostatic device, of the electrostatic attraction plate type (also called electrostatic chuck). It is possible to plan to magnetize the plate or elements located on a clamping plate, of the type described above, to cooperate with the chuck.
  • the installation as proposed in the present invention makes it possible to place a vibratory excitation source 210 of the hairspring or the hairspring blank, on a first side of the plate 10, and to arrange the means of measurement 220 of the vibration response of said hairspring or of the hairspring blank, typically a laser head, on a second side of the plate.
  • a vibratory excitation source 210 of the hairspring or the hairspring blank typically a laser head
  • the means of measurement 220 of the vibration response of said hairspring or of the hairspring blank typically a laser head
  • the installation 200 can be placed on one or the other side of the wafer.
  • the installation could preferably be placed on the device side.
  • the source of vibration excitation could advantageously in this case be placed on the side of the device layer and the measuring means placed on the side of the handle layer.
  • the opposite arrangement is obviously a possible alternative, particularly when the hairsprings or the blanks are accessible in a similar way, from one or the other side.
  • the vibration excitation source 210 is an acoustic source, and it is coupled to a divergent cone 212 directed towards the hairspring or the hairspring blank to be excited, as shown in the figure. Figure 4 .
  • the dimensions of the end of the cone are slightly larger than the engraving dimensions of the hairspring, in order to excite the entire hairspring.
  • the installation can advantageously be arranged on a mobile table, the position of which can be controlled precisely by actuators.
  • a movement can be planned in two orthogonal directions (in the plane of the wafer) or even three orthogonal directions (in the plane of the wafer and in a direction normal to the plane of the wafer).
  • the table In the reference frame of the measuring machine, the table is mobile, while the excitation source and the measuring means can be fixed.
  • the installation can therefore move with reference to the excitation source and the measuring means, to allow automatic and indexed movement between the different hairsprings to be measured.
  • the installation serves as support for a silicon layer of an SOI wafer or what remains of the wafer at the time of measurement, or for a simple wafer, if the etching process is carried out on a simple plate.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Testing Or Measuring Of Semiconductors Or The Like (AREA)
EP22183023.5A 2022-07-05 2022-07-05 Verfahren zur bestimmung der steifigkeit einer spiralfeder Pending EP4303668A1 (de)

Priority Applications (1)

Application Number Priority Date Filing Date Title
EP22183023.5A EP4303668A1 (de) 2022-07-05 2022-07-05 Verfahren zur bestimmung der steifigkeit einer spiralfeder

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
EP22183023.5A EP4303668A1 (de) 2022-07-05 2022-07-05 Verfahren zur bestimmung der steifigkeit einer spiralfeder

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EP4303668A1 true EP4303668A1 (de) 2024-01-10

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Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1422436A1 (de) 2002-11-25 2004-05-26 CSEM Centre Suisse d'Electronique et de Microtechnique SA Spiraluhrwerkfeder und Verfahren zu deren Herstellung
EP2215531A1 (de) 2007-11-28 2010-08-11 Manufacture et fabrique de montres et chronomètres Ulysse Nardin Le Locle SA Mechanischer oszillator mit einem optimierten thermoelastischen koeffizienten
WO2016128694A1 (fr) 2015-02-13 2016-08-18 Tronic's Microsystems Oscillateur mécanique et procédé de réalisation associe
EP3181938A1 (de) 2015-12-18 2017-06-21 CSEM Centre Suisse d'Electronique et de Microtechnique SA - Recherche et Développement Herstellungsverfahren einer spiralfeder mit einer vorbestimmten steifigkeit durch wegnahme von material
CH717357A2 (fr) * 2020-04-24 2021-10-29 Rolex Sa Spiral horloger en verre ou en céramique, à géométrie complexe.
EP3915788A1 (de) * 2019-09-16 2021-12-01 Sigatec SA Verfahren zur herstellung eines loses von uhrwerk-spiralfedern
EP4030243A1 (de) * 2021-01-18 2022-07-20 Richemont International S.A. Verfahren zur kontrolle und zur herstellung von uhrwerk-spiralfedern

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1422436A1 (de) 2002-11-25 2004-05-26 CSEM Centre Suisse d'Electronique et de Microtechnique SA Spiraluhrwerkfeder und Verfahren zu deren Herstellung
EP2215531A1 (de) 2007-11-28 2010-08-11 Manufacture et fabrique de montres et chronomètres Ulysse Nardin Le Locle SA Mechanischer oszillator mit einem optimierten thermoelastischen koeffizienten
WO2016128694A1 (fr) 2015-02-13 2016-08-18 Tronic's Microsystems Oscillateur mécanique et procédé de réalisation associe
EP3181938A1 (de) 2015-12-18 2017-06-21 CSEM Centre Suisse d'Electronique et de Microtechnique SA - Recherche et Développement Herstellungsverfahren einer spiralfeder mit einer vorbestimmten steifigkeit durch wegnahme von material
EP3915788A1 (de) * 2019-09-16 2021-12-01 Sigatec SA Verfahren zur herstellung eines loses von uhrwerk-spiralfedern
CH717357A2 (fr) * 2020-04-24 2021-10-29 Rolex Sa Spiral horloger en verre ou en céramique, à géométrie complexe.
EP4030243A1 (de) * 2021-01-18 2022-07-20 Richemont International S.A. Verfahren zur kontrolle und zur herstellung von uhrwerk-spiralfedern

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