• 专利附录
  • 专利说明
  • 权利要求
  • 类似技术
  • 同族专利
  • 引用文献
  • 法律状态
  • 优先权
    • 专利摘要:
    The invention relates to a watchmaking micromechanical component comprising a silicon-based substrate (1) having at least one surface, at least a portion of said surface having pores opening on the outer surface of the watchmaking micromechanical component and comprising an agent tribological (5). The invention also relates to a method for producing a watchmaking micromechanical component from a silicon-based substrate (1), said silicon-based substrate having at least one surface of which at least a portion is lubricated by an agent. tribological method (5), said method comprising, in order, the steps of: a) forming pores on the surface of the portion of said surface of said silicon-based substrate (1) b) depositing in said pores said tribological agent (5).
    公开号:CH711500A2
    申请号:CH01287/15
    申请日:2015-09-08
    公开日:2017-03-15
    发明作者:Dubois Philippe
    申请人:Nivarox-Far S A；
    IPC主号:
    专利说明:

    Field of the invention
    The present invention relates to a watch micromechanical component comprising a silicon-based substrate, lubricated by means of a tribological agent. The invention also relates to a method for producing such a watch micromechanical component.
    Background of the invention
    [0002] Silicon is a material increasingly used in the manufacture of micromechanical watchmaking parts, in particular parts that remain connected to a silicon-based substrate on which they have been machined.
    [0003] Compared to the metals or alloys conventionally used to manufacture micromechanical watchmaking parts, such as gears, or the components of the exhaust, silicon has many advantages. It is a very hard material, of a very light weight which allows it to present a very reduced inertia and consequently to improve the yield. Silicon also makes it possible to produce complex parts, or monobloc.
    However, just like the other materials used more conventionally in the watch industry, parts made from a silicon-based substrate must be lubricated.
    It is known to use for example a very fluid lubricant which promotes a low coefficient of friction in the case of low contact pressures. However, this type of lubricant has the disadvantage of having its effect fade especially at higher contact pressures due to the rupture of the lubricant film. It is known that supra-lubrication techniques, based on the formation of surface-deposited polymer brushes (polymer brushes) and their impregnation with a lubricant having an affinity with polymeric brushes, greatly reduce friction for a wide range of applications. solicitations. These highly flexible polymer brushes straighten up when impregnated with lubricant, forming a sort of sponge full of lubricant. Depending on the friction regimes, during large contact pressures, the filaments can easily compress and return lubricant to the contact. This results in the formation of a larger lubricating film which results in a substantial decrease in the coefficient of friction and wear. However, during long-term solicitations, these polymer brushes eventually degrade (wear, tearing of the surface), which no longer allows the coating of polymer brushes to perform its function.
    It is therefore necessary to propose a new method for lubricating a micromechanical watch part based on silicon to contain on the surface of the part to be lubricated sufficient amounts of lubricating agent to reduce the frequency of maintenance services watch movement comprising said piece.
    It is also necessary to propose a new method for lubricating a micromechanical watch part based on silicon to create lubrication conditions allowing a significant reduction in wear and friction coefficient, so as to increase reliability, the yield and consequently the power reserve of the watch movement comprising this piece, and this for a wide range of requests.
    Summary of the invention
    For this purpose, the present invention relates to a watchmaking micromechanical component comprising a silicon-based substrate having at least one surface.
    According to the invention, at least a portion of said surface of the silicon-based substrate has pores opening to the outer surface of the watch micromechanical component, said pores comprising a tribological agent.
    The present invention also relates to a method for producing a watchmaking micromechanical component from a silicon-based substrate, said silicon-based substrate having a surface at least a portion of which is lubricated by a tribological agent, said method comprising, in order, the steps of:<tb> a) <SEP> forming pores on the surface of the portion of said surface of said silicon-based substrate,<tb> b) <SEP> deposit in said pores said tribological agent.
    The formation of pores from the surface of the silicon-based substrate makes it possible to form a porous silicon-based superstructure having a certain degree of flexibility capable of accommodating different pressure regimes by deforming. In addition, this type of structure has cavities that can contain a long lasting reserve of lubricant.
    In addition, in the case where polymeric brushes are deposited on the porous silicon-based superstructure, the coating obtained is capable of gorging lubricant and restore it when these polymer brushes are compressed. This coating also promotes the penetration of the lubricant into the cavities of the porous silicon-based superstructure.
    Brief description of the drawings
    The objects, advantages and features of the present invention will appear more clearly in the following detailed description of several embodiments of the invention given solely by way of nonlimiting examples and illustrated by the appended drawings in which:<tb> figs. 1 to 2 <SEP> schematically illustrate the steps of a first variant of the manufacturing method according to the invention,<tb> figs. 3 to 5 <SEP> schematically illustrate the steps of a second variant of the manufacturing method according to the invention, and<tb> figs. 6 to 8 <SEP> schematically illustrate the steps of a third variant of the manufacturing method according to the invention.
    Detailed description of the invention
    With reference to FIGS. 1 and 2, the method for producing a micromechanical watchmaking part lubricated by a tribological agent from a silicon-based substrate 1 according to the invention first comprises a step a) of forming pores 2 from the surface of said silicon-based substrate 1 on an area of the silicon-based substrate 1 corresponding to an area to be lubricated. The pores 2 are arranged so as to open on the outer surface of the watchmaking micromechanical component. The silicon-based substrate 1 is chosen as a function of the watchmaking micromechanical component to be formed. The final shape of the silicon-based substrate 1 as a function of the watchmaking micromechanical component to be manufactured is given before or after the implementation of the method of the invention. In the present invention, the term "silicon-based substrate" refers to both a silicon layer in a substrate and a silicon substrate. Preferably, the silicon-based substrate 1 is a silicon wafer or an SOI wafer (Silicon-on-insulator). The pores may preferably be formed on the surface perpendicular to the plane of the substrate, that is to say on the flanks of the micromechanical part which are in friction, but also on the surface parallel to the plane of the substrate.
    Advantageously, this step a) can be carried out by a method chosen from the group comprising an electrochemical etching process, a "Stain-etch" type method, and a "MAC-Etch" type process. .
    The electrochemical etching process may be a process by electrochemical anodization. Its implementation requires the use of an electrochemical bath containing hydrofluoric acid in aqueous solution or mixed with ethanol in concentrations of 1 to 10%. Electrical current and electrodes are needed to create electrochemical conditions inducing silicon attack. Depending on the electrochemical conditions, different types of pores can be obtained. Such a method is known to those skilled in the art and does not require detailed information here.
    The "Stain-etch" type process is based on a wet attack of silicon resulting directly in the formation of porous silicon. Typically, the attack is carried out with a HF / HNO 3 / H 2 O solution with a HF: HNO 3 ratio of 50-500: 1. This method has the advantage of not requiring electrical input into the bath. Such a method is known to those skilled in the art and does not require detailed information here.
    Preferably, step a) is performed by a method of the "MAC-Etch" type. This process is based on the use of noble metal particles to catalyze local chemical attack reactions. Typically, a very thin layer (10-50 nm) of a noble metal (gold, silver, platinum) is deposited and structured randomly or by lift-off, attack, laser, etc. Preferably, the noble metal is gold. More particularly, gold particles in solution in an HF / H2O2 mixture can advantageously be used. The particle size may be between 5 and 1000 nm. The structuring can be obtained by lithography of gold, attack or lift-off. Another option is evaporation or sputtering of a very thin, non-closed layer (5-30 nm). Heat treatment may contribute to the formation of islands of gold.
    When the silicon with the noble metal layer is immersed in an aqueous solution of a HF / H2O2 mixture, the noble metal locally catalyzes the dissolution of silicon. This etching solution may typically comprise between 4 ml: 1 ml: 8 ml (48% HF: 30% H2O2: H2O) and 4 ml: 1 ml: 40 ml (48% HF: 30% H2O2: H2O). Silicon dissolution occurs preferentially under the metal, which then gradually sinks into the silicon. This reaction can be continued over great depths (> 100 mμ) according to propagation modes essentially influenced by the orientation of the silicon crystal, the surface arrangement, the doping and the bath chemistry. The method of "MAC-Etch" type has the advantage of not requiring electrical input into the bath while allowing the formation of very deep pores (> 100 mμ) in the silicon. It is therefore particularly suitable for the use, as a substrate, of SOI wafers generally used for the manufacture of watch components.
    Those skilled in the art know the parameters of the methods described above to implement so that the pores formed in the silicon-based substrate have an appropriate geometry and size.
    In particular, the pores may advantageously have an aspect ratio (depth: diameter ratio) of between 5 and 100.
    [0022] Preferably, the pores may have a depth greater than 100 μm, preferably greater than 200 μm and more preferably greater than 300 μm.
    As shown in FIG. 2, the formation of pores 2 in the silicon-based substrate 1 to a certain depth causes the formation, between the pores 2, of pillars 3 based on silicon on the same depth. Preferably, considering the silicon-based pillars as having a circular section, the pores 2 are formed so that the projected area of the pillars 3 based on silicon is less than 79% of the apparent total area so as not to have of silicon-based pillars touching each other.
    The second step b) of the method according to the invention consists in depositing in the pores 2, between the pillars 3, a tribological agent. The tribological agent is a lubricant, and can be liquid, for example in the form of an aqueous solution, or dry. In a preferred manner, said tribological agent is a perfluorocarbon polymer, such as polytetrafluoroethylene (PTFE), or any other appropriate tribological or lubricating agent.
    According to a first variant of the method of the invention, the tribological agent is deposited according to step b) directly into the pores 2 of the silicon-based substrate. This step b) can be carried out by a thin-layer deposition process, such as CVD, iCVD, PECVD. A suitable heat treatment may be applied to polymerize the tribological agent at temperatures in the range of 100 ° C to 300 ° C. Thus, large amounts of tribological agent can be stored near the surface of the silicon-based substrate, while maintaining a relatively high apparent surface hardness due to silicon.
    In a particularly advantageous manner, the parameters of the process for forming the pores 2 in the silicon-based substrate 1 according to step a) are chosen so that the pores 2 have an appropriate geometry and size so that the pillars 3, formed between the pores 2, constitute filaments 3 based on silicon. These filaments 3 have an aspect ratio (ratio depth: diameter) of between 5 and 100. The filaments form a flexible superstructure and are then impregnated with a tribological agent chosen to facilitate the wetting of the pores, according to step b) the process according to the invention.
    A substrate comprising silicon-based filaments can be used according to two other variants of the process of the invention.
    More particularly with reference to FIGS. 3 to 5, according to a second variant of the method according to the invention, it is provided according to step a) to produce in a silicon-based substrate 1 pores 2 so as to form between the pores 2 of the pillars 3 under the filament shape 3, as shown in FIG. 3. It is then planned between steps a) and b), a step c) depositing at least one wetting agent 4 of the tribological agent on the walls of the filaments 3 based on silicon. The wetting agent 4 is chosen to facilitate wetting and penetration of the tribological agent. It is applied to form a very thin layer (a few nanometers) in order to functionalize the walls of the filaments 3 based on silicon. Then the filaments 3 are impregnated with a tribological agent 5, according to step b), the tribological agent 5 being chosen to facilitate the wetting of the pores 2.
    With reference to FIGS. 6 to 8, according to a third variant of the method according to the invention, it is provided according to step a) to produce in a silicon-based substrate 1 pores 2 so as to form between the pores 2 of the pillars 3 under the filament shape 3, as shown in FIG. 6. It is then planned between steps a) and b), a step d) of depositing at least one polymer brush 6 on the walls of the filaments 3 based on silicon. Such a polymer brush 6 is described for example in the publications WO 2012 152 512 and WO 2014 009 059. The polymer brushes have filaments of shorter length than the silicon-based filaments so that the polymer filaments are protected by the Silicon filaments more mechanically resistant. Then the silicon-based filaments 3 and the polymer brushes 6 are impregnated with a tribological agent 5, according to step b), the tribological agent being chosen to facilitate wetting.
    The present invention also relates to a micromechanical watchmaker able to be obtained by the method described above. Said micromechanical watchmaking part comprises a silicon-based substrate 1 having at least one surface, this surface being able in particular to be intended to be in contact with a surface of another micromechanical part, said micromechanical parts being relatively movable relative to one another. the other.
    According to the invention, at least a portion of said surface has pores 2 opening to the outer surface of the watch micromechanical component, said pores 2 comprising a tribological agent.
    Advantageously, the pores 2 are made so as to form, between said pores, filaments 3 based on silicon.
    According to one embodiment, the silicon-based filaments 3 may comprise walls covered with at least one wetting agent 4 of the tribological agent 5, the silicon-based filaments being impregnated with the agent. tribological 5.
    According to another embodiment, the filaments 3 based on silicon may comprise walls covered with at least one polymer brush 6, the filaments 3 based on silicon and the polymer brush 6 being impregnated with the tribological agent 5.
    The method according to the invention makes it possible to manufacture filaments directly in the material of the silicon-based substrate with controlled geometries and mechanical flexural properties, allowing, in case of using polymer brushes, to maintain the behavior of supra. - Lubrication over a wide range of friction while increasing reliability. Thus, the process according to the invention overcomes the lack of mechanical strength of polymer brushes usually used in supra-lubrication. The structure formed of silicon-based filaments constitutes a lubricant reservoir capable of returning the sufficient amount of lubricant in the contact as a function of the stresses.
    The geometry of the pores and the silicon-based filaments can be optimized according to the friction regimes and tribological objectives referred to. Structuring of the silicon-based substrate can range from silicon-based filaments to open and disordered pores forming a spongy layer.
    权利要求:
    Claims (16)
    [1]
    1. micromechanical watchmaking component comprising a silicon-based substrate (1) having at least one surface, characterized in that at least a portion of said surface has pores (2) opening on the outer surface of the watchmaking micromechanical component and comprising a tribological agent (5).
    [2]
    2. Part according to claim 1, characterized in that the pores (2) have an aspect ratio (depth: diameter ratio) of between 5 and 100.
    [3]
    3. Part according to one of the preceding claims, characterized in that the pores (2) have a depth greater than 100 microns, preferably greater than 200 microns and more preferably greater than 300 microns.
    [4]
    4. Part according to one of the preceding claims, characterized in that it comprises, between the pores (2), filaments (3) based on silicon.
    [5]
    5. Part according to claim 4, characterized in that the filaments (3) based on silicon have an aspect ratio (depth: diameter ratio) between 5 and 100.
    [6]
    6. Part according to one of claims 4 and 5, characterized in that the filaments (3) based on silicon have walls covered with at least one wetting agent (4) of the tribological agent (5) the silicon-based filaments (3) being impregnated with the tribological agent (5).
    [7]
    7. Part according to one of claims 4 and 5, characterized in that the filaments (3) based on silicon have walls covered with at least one polymer brush (6), the filaments (3) based on silicon and the polymer brush (6) being impregnated with the tribological agent (5).
    [8]
    8. Part according to one of the preceding claims, characterized in that the tribological agent (5) is a perfluorocarbon polymer.
    [9]
    9. Part according to one of the preceding claims, characterized in that the silicon-based substrate (1) is a silicon wafer or wafer SOI (Silicon-on-Insulator).
    [10]
    A method of producing a watch micromechanical component from a silicon-based substrate (1), said silicon-based substrate having a surface of which at least a portion is lubricated by a tribological agent (5), said method comprising, in order, the steps of;a) forming pores (2) on the surface of the portion of said surface of said silicon-based substrate (1),b) depositing in said pores (2) said tribological agent (5).
    [11]
    11. The method of claim 10, wherein the pores (2) are arranged to form, between the pores, filaments (3) based on silicon.
    [12]
    12. The method according to claim 11, comprising, between steps a) and b), a step c) depositing at least one wetting agent (4) of the tribological agent (5) on the walls of the filaments ( 3) based on silicon.
    [13]
    13. The method of claim 11 comprising, between steps a) and b), a step d) depositing at least one polymer brush (6) on the walls of the filaments (3) based on silicon.
    [14]
    14. The method as claimed in one of claims 11 to 13, in which step a) is carried out by a process chosen from the group comprising an electrochemical etching process, a "Stain-etch" type process, and a method of type "MAC-Etch".
    [15]
    15. The method of claim 14, wherein step a) is carried out by a method of the "MAC-Etch" type.
    [16]
    16. Method according to one of the preceding claims, wherein step b) is carried out by a thin-layer deposition process.
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    同族专利:
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    引用文献:
    公开号 | 申请日 | 公开日 | 申请人 | 专利标题
    法律状态:
    优先权:
    申请号 | 申请日 | 专利标题
    CH01287/15A|CH711500B1|2015-09-08|2015-09-08|Watchmaking micromechanical piece comprising a lubricated surface and method for producing such a watchmaking micromechanical piece.|CH01287/15A| CH711500B1|2015-09-08|2015-09-08|Watchmaking micromechanical piece comprising a lubricated surface and method for producing such a watchmaking micromechanical piece.|
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