EP3839642A1 - Herstellungsverfahren von uhrenfedern und ätzmaske für ein solches verfahren - Google Patents

Herstellungsverfahren von uhrenfedern und ätzmaske für ein solches verfahren Download PDF

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Publication number
EP3839642A1
EP3839642A1 EP19218414.1A EP19218414A EP3839642A1 EP 3839642 A1 EP3839642 A1 EP 3839642A1 EP 19218414 A EP19218414 A EP 19218414A EP 3839642 A1 EP3839642 A1 EP 3839642A1
Authority
EP
European Patent Office
Prior art keywords
springs
plate
watch
etching
stiffness
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
EP19218414.1A
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English (en)
French (fr)
Inventor
Sylvain Jeanneret
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.)
Patek Philippe SA Geneve
Original Assignee
Patek Philippe SA Geneve
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 Patek Philippe SA Geneve filed Critical Patek Philippe SA Geneve
Priority to EP19218414.1A priority Critical patent/EP3839642A1/de
Publication of EP3839642A1 publication Critical patent/EP3839642A1/de
Pending legal-status Critical Current

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Classifications

    • 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
    • G04B1/00—Driving mechanisms
    • G04B1/10—Driving mechanisms with mainspring
    • G04B1/14—Mainsprings; Bridles therefor
    • G04B1/145—Composition and manufacture of the springs
    • 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 a method of manufacturing watch springs.
  • spring is meant any elastically deformable element to receive energy and / or produce a force or a movement.
  • watch springs are hairsprings intended to be fitted to balances, rocker, lever or hammer return springs, jumpers or flexible guides.
  • the present invention relates more particularly to the manufacture of watch springs by etching a plate of material. It is now well known in watchmaking to use engraving techniques such as laser engraving, plasma engraving, deep reactive ionic engraving (known as DRIE) or wet engraving to manufacture components in large numbers and precisely. watchmakers.
  • the most common engraving material is silicon.
  • Several types of silicon have been proposed as an engraving material in watchmaking, in particular monocrystalline silicon oriented along the crystallographic axis ⁇ 100> (cf. for example the patent EP 1422436 ), monocrystalline silicon oriented along the crystallographic axis ⁇ 111> (cf. for example the patent EP 2215531 ), monocrystalline silicon oriented along the crystallographic axis ⁇ 110> (cf.
  • the present invention aims to attenuate the dispersion of stiffness of watch springs obtained from the same plate of engraving material.
  • a method for manufacturing watch springs comprising a step consisting in etching the watch springs in at least part of the thickness of a plate, the plate being made of an anisotropic material in said at least one. part of the thickness, characterized in that the etching is carried out in such a way that the watch springs have different orientations in the plate to reduce their dispersion of stiffness.
  • the invention further proposes an engraving mask comprising an engraved design representative of watch springs, characterized in that in the engraved design the watch springs have different orientations such that by the engraving of at least a part, in material anisotropic, of the thickness of a plate through the etching mask, it is possible to obtain watch springs whose stiffness dispersion is reduced.
  • the method according to the invention uses an anisotropic etching material and exploits this anisotropy to reduce the stiffness dispersion of watch springs of the same geometry and of the same size.
  • the diagram of the figure 1 represents the modulus of elasticity of monocrystalline silicon in the (100) plane as a function of the crystallographic directions. It can be seen in particular that the modulus of elasticity varies between a minimum value and a maximum value over an angle of 45 °.
  • the teaching of the patent EP 3056948 B1 does not take into account the inhomogeneity of etching in the same plate. By orienting the spirals of the same plate in a particular direction, one gives them an average stiffness but one does not solve the problem of the dispersion of stiffness.
  • the figure 3 shows, at mark 12, a typical bell-shaped dispersion curve defining a number N of classes of balance springs. The objective of the invention is to reduce the number of classes, in other words to tighten the bell curve 12, as shown by the dotted line 13.
  • the invention is based on the observation that the etching inhomogeneity, and therefore the dispersion of stiffness, is repeated from one plate of etching material to the next when the parameters of the etching process are kept unchanged. As shown in figure 4 , it is possible to identify on the plate of engraving material, designated by 14, different zones Z1, Z2, Z3, etc. corresponding to different stiffnesses. In the case of plasma etching, in particular deep reactive ion etching, the areas are circular and concentric.
  • a zone Z2 and a zone Z4 can contain hairsprings having substantially the desired stiffness and therefore corresponding to a class located in the middle of the dispersion curve 12, while zones Z1, Z3, Z5 ... can contain springs.
  • balance springs having different stiffness from the desired stiffness and different from one zone to another.
  • the stiffnesses are substantially identical and belong to the same class. According to the invention, no measure is taken concerning the balance springs of zones Z2 and Z4 which have the desired stiffness.
  • the balance springs are oriented differently in the plate in order to modify their stiffness and to bring it closer to the desired stiffness value.
  • the hairsprings have the same orientation but the orientation varies according to the zone Zi where they are located, as shown schematically by figure 4 .
  • the orientation is defined for example by the oriented half-line 15 starting from the geometric center of the hairspring and passing through the outer end of the active part of the hairspring, as illustrated in figure 2 .
  • the differences in orientation between the balance springs in the different zones depend on the engraving parameters.
  • the maximum difference in orientation can be 45 °. It is typically at least 10 °, or even at least 20 °, or even at least 30 °.
  • the spirals are attached to the plate 14 by one or more bridges of material left during the etching, for example a bridge of material 16 at their outer end.
  • the stiffness of a given hairspring can be measured by coupling the hairspring to a balance of predetermined inertia and by measuring the frequency of the balance-spring assembly, this while the hairspring is still attached to the plate 14 or after its detachment.
  • the orientation to be given to each hairspring can be calculated as a function of the stiffness measured with respect to the desired stiffness and as a function of the geometry of the hairspring and of the anisotropy of the modulus of elasticity of the etching material.
  • FIG. 5 An example of an implementation of a method for manufacturing watch balance springs according to the invention, with silicon as an etching material, is shown in figure 5 .
  • a wafer 1 made of silicon-on-insulator type material known by the acronym SOI (Silicon-On-Insulator).
  • SOI Silicon-On-Insulator
  • the wafer 1 comprises an upper layer of silicon 2, a lower layer of silicon 3 and, between the two, an intermediate layer of silicon oxide 4.
  • the silicon is anisotropic, that is to say monocrystalline of type ⁇ 100 > or ⁇ 110>.
  • a photosensitive lacquer layer 5 is deposited on the upper silicon layer 2 and this layer 5 is structured by photolithography. More precisely, we expose the lacquer layer photosensitive 5 to ultraviolet rays through a mask 6 comprising a plate 6a transparent to ultraviolet rays and a structure to be transferred 6b carried by the plate 6a, the plate 6a being typically made of glass or quartz and the structure to be transferred 6b being typically made of chrome . Then the photosensitive lacquer layer 5 is developed and baked ( figure 5 (c) ). At the end of these operations, the photosensitive lacquer layer 5 has the same shape as the structure 6b and in turn constitutes a mask, said shape corresponding to that of a batch of balance springs to be manufactured.
  • the upper layer of silicon 2 is etched through the photosensitive lacquer mask 5 by deep reactive ion etching called DRIE (Deep Reactive Ion Etching) in order to form the balance-springs in this layer 2.
  • DRIE Deep Reactive Ion Etching
  • the etching is stopped by the intermediate layer d silicon oxide 4, thus making it possible to define a precise thickness for the balance-springs.
  • the number of balance springs is typically at least one hundred, preferably at least five hundred, more preferably at least six hundred. This number depends on the size of the plate 1 (typically 150 or 200 mm in diameter) and on the size of the balance springs.
  • the photosensitive lacquer mask 5 is then removed by chemical etching or plasma etching ( figure 5 (e) ).
  • a plate 8 formed by all or part of the upper silicon layer 2 etched is released from the plate 1.
  • This plate 8 contains a base structure and the balance springs attached to the base structure by bridges of material left during the engraving.
  • the spirals can be subjected to various treatments before being released from the plate 8.
  • a variant may consist in replacing the SOI wafer 1 with a simple wafer of anisotropic silicon and in etching the balance-springs throughout the thickness of the wafer.
  • the balance springs in the engraved pattern that constitutes the structure 6b of the etching mask 6, and therefore in the upper layer of silicon 2 then in the plate 8, the balance springs have different orientations chosen as a function of the anisotropy of the etching material (silicon of layer 2) to reduce their dispersion of stiffness, that is to say tighten the bell curve 12, according to the principle explained above.
  • a batch of balance springs that is more homogeneous in terms of stiffness is thus obtained, which makes it possible to significantly reduce the number of classes and therefore to ease the management of the stock of balance springs.
  • the operation of pairing the balance springs with balances is made easier and may even no longer be necessary.
  • the etching mask 6 could be a plate opaque to ultraviolet rays and engraved over its entire thickness (perforated mask or “shadow mask”).
  • the present invention is not limited to balance springs. It can be applied to any type of watch spring, for example to tilt, lever or hammer return springs, to jumpers, to flexible guides, in particular to flexible oscillator guides without pivots.
  • the watch spring in the invention in particular in the case of flexible guides, can be part of a monolithic component.

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Metallurgy (AREA)
  • Manufacturing & Machinery (AREA)
  • Micromachines (AREA)
  • Springs (AREA)
EP19218414.1A 2019-12-20 2019-12-20 Herstellungsverfahren von uhrenfedern und ätzmaske für ein solches verfahren Pending EP3839642A1 (de)

Priority Applications (1)

Application Number Priority Date Filing Date Title
EP19218414.1A EP3839642A1 (de) 2019-12-20 2019-12-20 Herstellungsverfahren von uhrenfedern und ätzmaske für ein solches verfahren

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
EP19218414.1A EP3839642A1 (de) 2019-12-20 2019-12-20 Herstellungsverfahren von uhrenfedern und ätzmaske für ein solches verfahren

Publications (1)

Publication Number Publication Date
EP3839642A1 true EP3839642A1 (de) 2021-06-23

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Family Applications (1)

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EP19218414.1A Pending EP3839642A1 (de) 2019-12-20 2019-12-20 Herstellungsverfahren von uhrenfedern und ätzmaske für ein solches verfahren

Country Status (1)

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EP (1) EP3839642A1 (de)

Citations (6)

* 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
EP3056948A1 (de) 2015-02-17 2016-08-17 Master Dynamic Limited Siliciumspiralfeder
EP3285124A1 (de) * 2016-08-17 2018-02-21 Richemont International SA Mechanischer resonator für uhrwerk, sowie herstellungsverfahren eines solchen resonators
US20180142749A1 (en) 2015-07-03 2018-05-24 Damasko Uhrenmanufaktur KG Spiral spring and method for its manufacturing
WO2019180596A1 (fr) 2018-03-20 2019-09-26 Patek Philippe Sa Geneve Procede de fabrication de composants horlogers en silicium

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
EP3056948A1 (de) 2015-02-17 2016-08-17 Master Dynamic Limited Siliciumspiralfeder
EP3056948B1 (de) 2015-02-17 2019-02-20 Master Dynamic Limited Siliciumspiralfeder
US20180142749A1 (en) 2015-07-03 2018-05-24 Damasko Uhrenmanufaktur KG Spiral spring and method for its manufacturing
EP3285124A1 (de) * 2016-08-17 2018-02-21 Richemont International SA Mechanischer resonator für uhrwerk, sowie herstellungsverfahren eines solchen resonators
WO2019180596A1 (fr) 2018-03-20 2019-09-26 Patek Philippe Sa Geneve Procede de fabrication de composants horlogers en silicium

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