Method for making opening on glass or sapphire watch component

Abstract

To provide a method for making an opening on a glass or sapphire watch component.SOLUTION: In a first step (100), a glass or sapphire blank is manufactured or supplied. In a second step (200), a geometric shape of an opening is defined and the opening is cut in a form of a hole or a contour by a laser filament formation method. In a third step (300), a watch component including the opening is separated from scraps obtained from the filament formation method by chemical etching.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a method of creating an opening in a glass or sapphire watch component.

[0002] The present invention further relates to a wristwatch comprising a glass or sapphire watch component having at least one opening created using this method.

[0003] The present invention relates to the manufacture of watch components made from brittle materials such as glass or sapphire.

Background Art

[0004] Machining of watch components such as glass is very delicate, and a high scrap rate is observed during drilling operations or when creating openings, especially due to the presence of excessive chips.

Summary of the Invention

[0005] The object of the present invention is to develop a method of creating holes or openings in watch components made of glass or the like without cracking or chipping.

[0006] Towards this end, the present invention relates to a method of creating an opening in a watch component made of glass or sapphire as claimed in claim 1.

[0007] The present invention further relates to a wristwatch comprising a glass or sapphire watch component having at least one opening created using this method.

Brief Description of the Drawings

[0008] The objects, advantages and features of the present invention will be better understood by reading the following detailed description given with reference to the accompanying drawings.

[0009]

Figure 1

Embodiments for Carrying Out the Invention

[0010] When manufacturing a watch dial made of glass or sapphire, particularly a watch dial integrated with a solar cell, it is necessary to develop a precise glass drilling method that has no chips or shavings, no taper, and meets the impact test conditions.

[0011] Such a drilling method is required to create holes for passing needles through a crystal or dial made of glass or sapphire, any other similar material (particularly enamel), or to create apertures, index holes, or any other openings. In the following description, the general term "glass" is used to designate any of these materials.

[0012] A number of possible methods are conceivable.

[0013] The first method consists of cutting the glass by means of a laser, i.e., by continuous ablation (etching) of the material. The cutting is performed by continuous ablation of multiple layers of glass in multiple paths. According to this, laser focusing is required so that the glass is cut in a stepped shape until a hole is formed. Therefore, this method results in a relief where mechanical stress concentrates during the impact test, making the parts weaker.

[0014] The second method is the cutting of glass by chemical mechanical machining using the "SACE" (Spark Assisted Chemical Etching) technique. This technique is a micromachining technology for non-conductive materials (mainly glass) based on thermal-assisted etching. Generally, during spark-assisted chemical etching, the material is removed in the depth direction at a rapid rate of up to 100 μm / s for the first 100 μm, and then the rate drops for depths exceeding 300 μm. The glass to be drilled is immersed in an alkaline solution (NaOH or KOH). A tool heated between 500°C and 600°C is driven into the glass, and the glass around the tool is chemically etched by the thermal energy. By moving the tool, the glass is drilled and cut according to the pattern imposed on the tool. According to this approach, the glass can be chemically etched and passes the impact test, but it is particularly time-consuming.

[0015] The third method involves cutting by laser filament formation and separation. The glass is first punched using a laser method called filament formation with a laser beam focused by a conical lens (bessel lens). Laser filament formation is involved in the propagation of a laser beam in a transparent medium without diffraction due to the optical Kerr effect that causes a change in the refractive index of the medium in the presence of a strong laser field, resulting in self-focusing of the beam. This regime is advantageously obtained by propagating an optical pulse emitted by an amplified femtosecond laser. The glass is perforated from end to end at regular intervals (5 μm to 10 μm) by small holes with a diameter of a few μm (especially 2 μm to 3 μm). A CO2 laser then passes twice through the punched contour. This locally heats the glass, and the glass is separated along the filament path by thermal shock. This technique is very fast, but a cutting line is required to release the parts from the glass plate. Therefore, it is difficult, if not impossible, to remove a small disk from the glass plate without creating a cutting path in the disk.

[0016] In summary · According to the first laser cutting method, it is possible to obtain geometric shapes including holes and contours with low productivity and low resistance to impact and bending of the product. · According to the second cutting method by "SACE" type chemical mechanical machining, it is possible to obtain geometric shapes including holes and contours with very low productivity and good resistance to impact and bending of the product. · According to the third cutting method by laser filament formation and separation, it is possible to obtain geometric shapes including only contours with high productivity and excellent resistance to impact and bending of the product.

[0017] Therefore, an object of the present invention is to develop a new method that eliminates the drawbacks of the above three methods and combines their advantages. With the new method, it becomes possible to obtain geometric shapes including holes and contours with high productivity and excellent resistance to impact and bending of the product.

[0018] That is, the subject of the present invention is a fourth approach that allows achieving geometric shapes obtained by chemical spark assisted chemical etching (SACE) in combination with the productivity of laser filament formation. Filament formation is used to manufacture selected geometric shapes on a glass plate. The filament path is then selectively cut by etching in an alkaline solution (KOH or NaOH).

[0019] A method for manufacturing an opening in a glass or sapphire watch component according to the present invention includes a first step 100 in which a glass or sapphire blank is manufactured or supplied. In a second step 200, the geometry of the opening is defined, and the opening is cut in the form of a hole or a contour by a laser filament formation method using a picosecond laser whose beam is focused, particularly by a conical vessel lens. In a third step 300, the watch component including the opening is separated from the scrap obtained from the filament formation method by chemical etching.

[0020] The filament formation step according to the present invention is preferably carried out using a filament-forming laser having ultrashort infrared pulses, in particular a picosecond laser or an infrared femtosecond laser.

[0021] According to the present invention, good results are obtained with a picosecond laser having a frequency between 170 kHz and 1000 kHz, a pulse width of less than 15 ps, and a wavelength in the vicinity of 1064 nm, i.e., a picosecond laser having a maximum deviation of 10% on either side of this nominal value. These parameters are well suited for providing openings in the dial or case back of a sapphire crystal or glass crystal.

[0022] For other experimental optical applications, a femtosecond laser having a pulse duration between 100 and 200 femtoseconds and a frequency between 0.5 Hz and 10 Hz can be used. For example, a laser having a pulse duration of 150 femtoseconds, a wavelength of 800 nm, and a frequency of 1 kHz, or a laser pulse having a pulse duration of 120 femtoseconds, a wavelength of 800 nm, and a frequency of 1 kHz, such as a laser generated by titanium-sapphire amplification, can be used. However, it goes without saying that the working time sufficient and well suited for watch manufacturing applications is much longer than that achieved using picosecond lasers.

[0023] In a second step 200, a plurality of perforations are formed in the glass. These perforations have a size between a few micrometers, in particular between 1 micrometer and 10 micrometers, and are spaced apart at intervals of a few micrometers, in particular between 2 micrometers and 20 micrometers, and in particular at intervals between 5 μm and 7 μm.

[0024] Advantageously, the glass used is aluminosilicate, for example a glass having a low coefficient of thermal expansion, similar to that of a silicon wafer, high thermal stability, high optical quality, excellent dielectric properties, and very low roughness, without alkali, arsenic or antimony.

[0025] Chemical etching is carried out in an alkaline solution of either potassium hydroxide (caustic potash) or sodium hydroxide (caustic soda) at a temperature between 100°C and 120°C. Since multiple plates can be processed in parallel, high productivity can be obtained despite the long etching time of several hours (especially 3 to 8 hours).

[0026] There are almost no chips less than 20 μm on the cut edge thus manufactured. This result is the factor for obtaining very high impact strength characteristics.

[0027] The present invention further relates to a timepiece component made of glass or sapphire according to this method.

[0028] Specifically, it relates to a timepiece component on which a solar cell is deposited, for example, a dial having a center hole or an aperture.

[0029] Specifically, an opening is made in a timepiece component intended to receive a solar cell. After the third step 300, in the fourth step 400, the solar cell is deposited on the glass of the component to manufacture the dial or crystal of a photovoltaic wristwatch.

[0030] Once an opening such as a central hole or an aperture is created using the above method, it becomes easy to deposit a solar cell on the glass to form the dial of the photovoltaic wristwatch. In the case of a thin-film solar cell, the solar cell is directly deposited on the glass or added to the glass using methods well-known to those skilled in the art, such as implementing amorphous silicon, perovskite (a perovskite solar cell is a type of solar cell whose active layer is made of a material having a perovskite structure of the general formula ABX3. Here, A is typically a cation such as methylammonium CH3NH3+ (MA), formamidinium CH(NH2)2+, or cesium Cs+, B is a cation such as tin Sn2+ or lead Pb2+, and X is a halide anion such as chloride Cl-, bromide Br-, or iodide I-1,2), CIGS (copper, indium, gallium, selenium or sulfur), cadmium telluride compounds, etc.

[0031] The present invention further relates to a wristwatch comprising a glass or sapphire watch component having at least one opening made using this method, in particular a crystal, a dial or a back cover.

[0032] The method according to the present invention makes it possible to obtain high productivity and, surprisingly, significantly higher mechanical strength of the parts than can be obtained by currently used SACE chemical mechanical processing, i.e., spark-assisted chemical etching techniques, or laser cutting by ablation.

[0033] In summary, the present invention enables the manufacture of all conceivable glass part designs, holes and contours, and provides high productivity. Furthermore, the resistance of the parts to mechanical bending tests is surprisingly significantly better than that of the other techniques mentioned above, in particular SACE chemical mechanical processing, and the force applied before breakage is approximately four times greater.

[0034] The application of the present invention to the crystal and dial of a wristwatch is particularly appropriate.

Claims

1. 1. A method for manufacturing an opening in a glass or sapphire watch component, comprising: in a first step (100) a glass or sapphire blank is manufactured or supplied; in a second step (200) the geometry of the opening is defined and said opening is cut in the form of a hole or a profile by a laser filamentation process; and in a third step (300) said watch component comprising said opening is separated from the scrap obtained from said filamentation process by chemical etching.

2. 2. The method of claim 1, wherein in the second step (200), the laser filamentation is performed using a picosecond laser whose beam is focused by a conical Bessel lens.

3. 3. The method according to claim 2, characterized in that an infrared picosecond laser is used with a frequency between 170 kHz and 1000 kHz and a pulse duration of less than 15 ps.

4. 4. The method of claim 3, wherein the perforations are made in the glass with a wavelength of about 1064 nm.

5. 2. The method of claim 1, wherein in the second step (200) a plurality of perforations are made in the glass, the perforations being between 1 μm and 10 μm in size and spaced apart at intervals of 2 μm to 20 μm.

6. 6. The method of claim 5, wherein the perforations are made in the glass and spaced at intervals of 5 to 7 μm.

7. 2. The method according to claim 1, characterized in that during the first step (100) an aluminoborosilicate is used that has a thermal expansion coefficient similar to that of a silicon wafer, without alkali, arsenic or antimony.

8. 2. The method of claim 1, characterized in that during said third step (300), chemical etching is carried out in an alkaline solution at a temperature between 80° C. and 120° C. for a period of between 3 hours and 8 hours.

9. said opening being made in a timepiece component intended to receive a solar cell; After said third step (300), in a fourth step (400), solar cells are deposited on the glass of said component to produce a dial or crystal of a photovoltaic watch. The method according to claim 1 , characterized in that

10. 10. The method of claim 9, characterized in that the solar cell, which is a thin-film solar cell, is deposited directly on the glass.

11. 10. The method of claim 9, wherein the solar cell is attached to the glass.

12. 13. A watch comprising a glass or sapphire watch component having at least one aperture made using the method of claim 1.

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