EP1070999A1 - Method for shaping the surface of clockwork pieces - Google Patents

Abstract

The method involves applying a film-forming lacquer to the timepiece component by electrophoresis to create a closed coating. Selective local removal or alteration of the coating forms a mask for use in a surface structuring method. Prior to application of the film-forming material, the component is preferably cleaned in an ultrasonic bath, chemically deoxidised, cathodically degreased. The surface is then neutralised and activated. An Independent claim is included for clock components such as a decorative inscription.

Description

The present invention relates to a method for Surface design of clockwork parts according to the generic term of claim 1.

As is known, clockworks are manufactured with the highest precision, nowadays manufactured down to the micrometer range. In particular, parts of high-quality movements are included Decorations and inscriptions provided for those of his the watch manufacturer has the same high demands as for the functional aspects. The routine quality control of the parts even the smallest irregularities and errors in these Surface designs and leads to complaints.

In principle today there are high-precision, photographic processes available to get complicated with relatively little effort To produce surface designs. In the watch sector So far, however, these methods have been very limited be used.

The photographic processes generally require one Covering the surface to be processed with a mask, usually a varnish or a film-forming in general Material. Through local exposure and development individual areas exposed, which are an etching process or otherwise subject to processing.

For the reasons mentioned above, however, it would be necessary Watch parts on all sides with a complete protective cover to provide. So far, however, this was only for parts simple, 3-dimensional design possible, such as B. a rotor, consisting of rotor carrier and flywheel, for automatic lifts. For the other parts of the clock, which are next to breakthroughs and holes with diameters in the millimeter range and below as well additionally the finest threads with only one or two Such threads could have such a gapless Coverage cannot be guaranteed. For this reason to this day the surface design of these - also very much expensive - time-consuming parts due to mechanical Engraving or similar, material-removing processes carried out.

These known methods work on the principle that Material is removed from the clockwork parts. This can a weakening of the Materials arise that are no longer negligible.

It is therefore an object of the present invention to to specify a method that the surface design of Clockwork parts allowed using imaging techniques. A another object of the present invention is a Process for the surface design of clockwork parts to indicate that works without the removal of material.

A process that at least solves the first-mentioned task is specified in claim 1. Give the further claims preferred embodiments and applications of the method on.

It was found that even complicated Watch parts, even with small and tiny holes that are provided with screw thread, a gapless Coverage can be achieved when the cover material is through an electrophoretic process is applied with in other words, an electrophoretic lacquer is used. This observation is surprising, but it is also explainable because the electrophoretic deposition of the paint automatically to the exposed areas of the coating object is directed. With today known methods in which the object with the help of Contacting device in the electrophoresis bath is immersed, the contact points naturally remain uncoated. This precisely defined irregularity in however, the cover can be easily targeted Applying the covering material are closed, e.g. B. by dripping on or another type of application.

Those parts of the clockwork part that one Surface design should be subjected to appropriate procedures exposed. This is preferably done through an imaging process. To do this, a Photosensitive electrophoresis varnish used, the after exposed and developed after application and drying, after which the processing batches are exposed. For the Watch parts has shown that only one after the Positive principle working, light-sensitive lacquer can be used because reliable exposure in the Otherwise, holes and breakthroughs of the smallest size are not can be ensured and when using a Negative varnish there is a risk that these lots undesirably exposed to the design process become.

One possibility of surface design on the sun exposed areas is the etching, which is a removal of the Material causes. However, it is now also possible to use material-building processes such as deposits from the gas phase (CVD and PVD processes) or that Deposition by means of galvanic processes (electroforming).

The development of the method according to the invention Difficulties become apparent when is taken into account that the holes in watch parts often Diameters from 0.40 mm to 4 mm with a length of less than 1 mm to a few millimeters and / or through Aspect ratios (aspect ratios) from 1: 2 to 1: 4 mark (e.g. concrete diameter 0.4 mm for a Hole length of 0.9 mm). An aspect ratio less than 1 denotes a hole with a diameter that is smaller is than the length of the hole. In addition, the holes still be threaded.

On the other hand, there is a dissolution of those on the surface structures to be applied in the range of some Micrometers required. There is another difficulty in the fact that the parts of the clock also where the Surface design should take place, are curved, however, no distortion due to the curvature structure to be applied may be caused, whereby there are special requirements for the exposure process put. Exposure processes that have such problems consider, but are known per se and could Surprisingly, to implement the inventive Process are used.

In this context it is also conceivable, other than Photosensitive procedure to remove the cover too use, e.g. B. targeted by a laser beam or other type of radiation, with sufficient precision aligns. Consider z. B. also mechanical or thermal processes; because the cover over the Material of the watch parts is relatively easy to edit, can be used in particular automated processes be used for direct machining of the clockwork parts are unsuitable. Depending on it can then also on the photo-sensitive property of the lacquer can be dispensed with.

As photosensitive electrophoresis lacquers have especially those that have already proven to be suitable known from the production of multilayer printed circuit boards are.

The invention is further intended to be an exemplary embodiment are explained.

Fig. 1:

Teilschnitt durch eine erfindungsgemäss beschichtete Oberfläche mit Erhebungen;

Figg. 2a und b:

Teilschnitte durch konventionell beschichtete Oberflächen in der Umgebung eines Loches;

Fig. 3:

Teilschnitt wie Figur 2, jedoch erfindungsgemäss beschichtete Oberfläche;

Fig. 4:

Teilschnitt durch ein beschichtetes Uhrenteil mit eingesetztem Edelstein;

Fig. 5:

Teilschnitt durch die Randzone eines Rotors eines automatischen Uhraufzugmechanismus.

The figures show:

Fig. 1:

Partial section through a surface coated according to the invention with elevations;

Fig. 2a and b:

Partial cuts through conventionally coated surfaces in the vicinity of a hole;

Fig. 3:

Partial section as in FIG. 2, but surface coated according to the invention;

Fig. 4:

Partial section through a coated watch part with inserted gemstone;

Fig. 5:

Partial section through the edge zone of a rotor of an automatic watch winding mechanism.

The lacquer layer according to the invention is shown in the figures Better visibility displayed disproportionately thick.

Degreasing:

• Ultraschall-unterstützte Entfettung mit chemischen Mitteln bei erhöhter Temperatur, z. B. 70 °C, in wässrigem Medium;
• chemische Entfernung der oberflächlichen Oxidschicht;
• elektrolytische Entfettung, wobei die Uhrenteile als Kathode geschaltet sind, bei erhöhter Temperatur, z. B. 50 °C, und einer Stromdichte von 2 - 5 A/dm²;
• Neutralisierung und Aktivierung der Oberfläche.

The watch parts are first thoroughly cleaned and especially degreased. This is done in several ways:

• Ultrasonic-assisted degreasing with chemical agents at elevated temperatures, e.g. B. 70 ° C, in aqueous medium;
• chemical removal of the surface oxide layer;
• electrolytic degreasing, the clock parts being connected as cathode, at elevated temperature, e.g. B. 50 ° C, and a current density of 2 - 5 A / dm ² ;
• Neutralization and activation of the surface.

Depending on the current requirements, the cleaning process can be designed according to the following 3 variants:

Degreasing variant 1

1) Ultrasonic assisted chemical degreasing elevated temperature, e.g. B. 70 ° C (chemical agents: Sodium hydroxide, sodium metasilicate, phosphate, sodium phosphate, Sodium pyrophosphate, complexing agent [EDTA or Gluconate]).

2) Chemical removal of the surface oxide layer: Sodium bisulfate, organic acid (e.g. short chain Amino acids), sodium hydrogen bifluoride, wetting agent in aqueous solution.

3) Electrolytic degreasing: additives to the aqueous Electrolyte: sodium carbonate, sodium metasilicate, Sodium phosphate, sodium hydroxide, wetting agent.

4) Neutralization / activation: sodium bisulfate, organic Acids, sodium hydrogen bifluoride, wetting agents in aqueous Solution.

Degreasing variant 2 (especially for brass)

1) Pre-cleaning: anionic wetting agent, inhibitors (protection against attack of the workpiece surface in subsequent Process steps), amide soap and isopropyl alcohol in aqueous solution.

2) Degreasing by ultrasound as in variant 1.

3) Chemical removal of the surface oxide layer as in Version 1.

4) Electrolytic degreasing as in variant 1. Temperature z. B. 70 ° C and current density 2 - 5 A / dm ² . Electrolyte: aqueous solution of sodium carbonate, sodium metasilicate, sodium phosphate, sodium hydroxide and wetting agent.

5) Neutralization / activation: as in variant 1, additional Inhibitors (see above 1).

Degreasing variant 3 (especially for copper)

1) Degreasing in soap solution with ultrasound at 65 ° C.

2) Rinse with tap water.

3) Chemical degreasing at 75 ° C in acidic solution of CP1018 (OMI, Switzerland).

4) Rinse with tap water.

5) Microetch at 20 ° C in an aqueous solution of AD 485 (Enplate Imasa) or Circuposit Etch 3330 (Shipley).

6) Rinse with tap water, 2x.

7) Rinsing twice with water, which was cleaned by reverse osmosis and has a conductivity of max. 5 µs / cm ² .

Applying the cover, exposing and developing:

• Zweimaliges Spülen mit deionisiertem Wasser mit einer Leitfähigkeit von höchstens 10 µs/cm².
• Elektrophoretische Abscheidung des Fotoresist-Lacks PEPR 2400 (Shipley Company Inc., USA: Lack auf der Basis von Polyacrylat; weitere Inhaltsstoffe: 2-Octanon, N-Methyl-2-pyrrolidon) bei einer Spannung von 150 V während einer Minute. Die Dauer des Elektrophoreseprozesses richtet sich u. a. nach der zu erreichenden Dicke der Abdeckung. Die entsprechenden Angaben können der technischen Beschreibung des Lacks entnommen werden; für den vorliegenden wird angegeben, dass eine Nenndicke von 4 - 6 Mikrometern in ca. 60 Sek. erreicht wird. Der Strom stellt sich selbständig während der Abscheidung ein. Insbesondere wurde beobachtet, dass nahezu unabhängig vom Werkstück der Elektrophoresestrom innerhalb ca. 1 Minute praktisch verschwindet. Die Beschichtung kann daher beendet werden, wenn ein gegenüber dem Anfangsstrom wesentlich niedrigerer Grenzstrom unterschritten wird (z. B. 5 % des Anfangsstroms oder weniger). Wird dieser Grenzstrom nicht in dieser Zeit unterschritten, so bestehen in der Regel Probleme, z. B. mangelhafte Kontaktierung oder lückenhafte Beschichtung. Es kann dann das Beschichtungsverfahren nochmals durchlaufen werden.Die Schichtdicke wird, wie vom Hersteller vorgeschlagen, über Zusatz von PEPR 2400 TC (TC = thickness controller) [Shipley] eingestellt.
• Intensive Spülung, um lose anhaftende Lackpartikel zu entfernen.
• Trocknung: Dauer z. B. ca. 15 Min. bei einer Temperatur von ca. 120 °C.
• Belichtung: Für die Belichtung werden die Teile in eine Aufnahme eingesetzt. Es können auch Mehrfachaufnahmen für die Belichtung mehrerer gleicher oder evtl. auch verschiedener Teile verwendet werden. Die Belichtung erfolgt bei der für diesen Lack optimalen Wellenlänge von 380 - 420 nm bei der vorgeschriebenen Luftfeuchtigkeit von 40 - 60 %. Die Belichtungsdauer richtet sich nach der Stärke der Lampe, die mittels eines Graukeils festgelegt werden kann. Die nötige Bestrahlungsdosis ist stark abhängig vom Bestrahlungsgerät und dem Messgerät, so dass die vom Hersteller angegebenen Werte allenfalls eine Grössenordnung angeben. Ebenso hängt die Bestrahlungsdauer von den Eigenschaften der Bestrahlungsanlage ab. Beim angegebenen Lack und der optimalen Wellenlänge liegt sie jedoch im allgemeinen im Bereich von 10 Sekunden bis wenigen Minuten.
• Entwickeln: Die Entwicklung des Lacks PEPR 2400 geschieht durch eine einprozentige Lösung von Calciumcarbonat.

These steps are essentially carried out according to the specifications of the paint manufacturer:

• Rinsing twice with deionized water with a conductivity of at most 10 µs / cm ² .
• Electrophoretic deposition of the photoresist lacquer PEPR 2400 (Shipley Company Inc., USA: lacquer based on polyacrylate; further ingredients: 2-octanone, N-methyl-2-pyrrolidone) at a voltage of 150 V for one minute. The duration of the electrophoresis process depends, among other things, on the thickness of the cover to be achieved. The relevant information can be found in the technical description of the paint; for the present one it is stated that a nominal thickness of 4-6 micrometers is reached in about 60 seconds. The current adjusts itself automatically during the deposition. In particular, it was observed that the electrophoresis current practically disappears within approximately 1 minute, regardless of the workpiece. The coating can therefore be terminated if the limit current falls far below the initial current (e.g. 5% or less of the initial current). If this limit current is not fallen below during this time, there are usually problems, eg. B. poor contact or incomplete coating. The coating process can then be run through again. The layer thickness is set, as suggested by the manufacturer, by adding PEPR 2400 TC (TC = thickness controller) [Shipley].
• Intensive rinsing to remove loose paint particles.
• Drying: duration z. B. about 15 minutes at a temperature of about 120 ° C.
• Exposure: The parts are inserted into a holder for the exposure. Multiple exposures can also be used to expose several identical or possibly different parts. The exposure takes place at the optimal wavelength for this lacquer of 380 - 420 nm at the prescribed air humidity of 40 - 60%. The exposure time depends on the strength of the lamp, which can be determined using a gray wedge. The necessary radiation dose is strongly dependent on the radiation device and the measuring device, so that the values given by the manufacturer at most indicate an order of magnitude. The duration of the irradiation also depends on the properties of the irradiation system. With the specified lacquer and the optimal wavelength, however, it is generally in the range from 10 seconds to a few minutes.
• Develop: The PEPR 2400 is developed using a one percent solution of calcium carbonate.

The above steps from applying the lacquer to exposing are in a clean room of class 10000, preferably 1000 or better, done.

Cleanrooms are currently classified as follows: Clean room class Maximum permitted dust level VDI 2083 US Fed. Hr 209b Particles per m ^{3 of} air > 0.5 µm > 5 µm 3rd 100 4 x 10 ³ --- 4th 1000 4 x 10 ⁴ 3 x 10 ² 5 10,000 4 x 10 ⁵ 3 x 10 ³ 6 100000 4 x 10 ⁶ 3 x 10 ⁴

Design of the surface

The surface design is then transferred to the exposed parts of the clockwork part. A Etching or engraving can be carried out using known stains on the Made of iron chloride or copper chloride become. The exact composition is the Material of the movement part adapted, the Compatibility with the masking lacquer must be observed. For example, the PEPR 2400 lacquer cannot provide basic solutions be used as this is replaced by basic solutions becomes.

Instead of the material-removing engraving or etching material-applying processes can also be used. On such a process is electroforming, in which a galvanic process relatively thick metal layers can be applied. Another option is there in the application of the known methods for deposition the vapor phase, e.g. B. PVD (Physical Vapor Deposition) and CVD (Chemical Vapor Deposition). It is also possible to do this three processes as well as other conceivable processes in Use combination.

After finishing the surface design, the paint replaced by a conventional method, e.g. B. by means of a Sodium hydroxide solution as suggested by the manufacturer.

The figures illustrate the properties of the coating of watch parts according to the invention.

FIG. 1 shows a surface 1 with strong elevations 2, e.g. in the order of 1 mm and more. The Lacquer layer 3 follows the topography of the surface almost constant thickness. Typical layer thicknesses are in Range 3 µm - 5 µm.

In the case of a varnish that is immersed or otherwise conventional method is applied, one observes in contrast, a significantly reduced thickness at the convex Edges 4. This creates the risk that the paint layer at these edges 4 too thin and therefore too little resistant for the following processing steps or no longer exists.

Another, unfavorable quirk of conventional Paint coatings is that the layer depends on Application technology is uneven, e.g. in part 5 between the elevations 2 is very thick. This will make a high-precision exposure of finely structured patterns photographic process difficult because of different Thickness etc. different exposure times become necessary.

Figure 2a shows a conventional paint layer 7 in the Surrounding a hole 8, which has a thread. The hole 8 is completely filled with the paint 7. Nevertheless the lacquer layer at the edge 9 of the hole falls much thinner from, which results in the above-mentioned dangers.

The complete filling of the hole 9 with paint 7 leads to protect the perforated wall from further processing, however, this complete filling is with conventional techniques neither controllable nor reproducible feasible. It is rather a poet Closure, but not complete filling of hole 9 to observe. It would therefore have all the holes still on it checked whether they are adequately coated with the protective lacquer filled and closed tightly at all openings.

On the other hand, only so little varnish is used that the hole remains consistent and only the walls with one layer then the layer falls at the tips 10 the threads again very thin with the risk that the threads are not protected (Figure 2b).

Figure 3 shows the same situation as Figure 2, but with a lacquer layer 3 according to the invention clarifies that the lacquer layer 3 is not just a layer uniform thickness that also forms burrs (e.g. on Thread) and edges, but also much thinner can be held, increasing the precision of the imaging Procedure is increased.

FIG. 4 shows the layer 3 according to the invention in the Surrounding a ruby 11, which is in a metallic watch part 12 is inserted. Layer 3 runs with constant Thickness up to the hole 14 and forms a tight seal 15 at the transition from ruby 11 to part 12.

With conventional coatings there is because of different surface properties of the ruby in the Compared to the material of the watch part there is a risk that none the layer on the ruby is sealed and thus the edge zone of the watch part 12 is not perfectly protected. At most, a conventional coating could do that too covering the ruby safely. This However, it would have to be relatively thick, which means that again Problems with the exposure of structured surface parts of the clock part 12 result.

Figure 5 illustrates the problems in coating a Rotors 20, as used in automatic watches. The Inertia 20 usually consists of a rotor carrier, 21, on the periphery of which a flywheel 23 is attached, which consists of a heavy metal. The rotor carrier 21 e.g. made of brass, the flywheel 23 made of tungsten. The two parts are by rivets 24 or one Bolted together. That remains however, inevitably a thin gap 26. This gap has a variable width, e.g. 0.1 mm - 0.3 mm. But also between the actually abutting surfaces 27 of the rotor carrier 21 and the flywheel 23 can still be small and smallest Form joints.

With conventionally applied paints, here a gap-free cover, in particular in the gap 26 consistent quality cannot be guaranteed.

With the method according to the invention, however, was problem-free with high reliability a high quality, complete coating obtained as in the figure shown.

In general, the superiority of the process according to the invention in the very low Reject rate that is below 5%, usually in the range of 1 is up to 2% and is equivalent or even better than is the one with manual, mechanical processing.

It should be noted that the invention is not based on the specified electrophoretic lacquer is limited. Rather, it can be assumed that everyone electrophoretic paint can be used, especially if its use in the field of multilayer circuit boards is known is. The photosensitivity is not essential necessary, as other methods of exposing covered Batches are usable, e.g. B. by laser beam. The Can be exposed using a laser beam or other methods of course also in combination z. B. with the described Exposure methods are used.

Electrophoretic lacquers are not photosensitive already known in a colorless version for protection metallic surfaces against oxidation or browning and colored for combined coloring and protection of metals, e.g. B. automobile bodies.

The procedures for applying the electrophoretic lacquers and Z. T. pretreat the surface, as well as for the Detachment after finishing the surface design can be done in usually take place according to the information provided by the manufacturer, such as this is also essentially the case in the exemplary embodiment is. The pretreatment of the surfaces of the clockwork parts (Degreasing, deoxidation, etc.) is also different conceivable if the special shown Approach has proven particularly successful.

The structuring method according to the invention is regularly together with other procedures for Surface design used, such as mechanical Machining (grinding, polishing, sandblasting, etc.) and in particular applying a galvanic coating to the are known.

For simply shaped parts, especially without openings and holes, is another way of applying the top coat conceivable, e.g. B. dipping, spraying or laminating.

Claims (7)

Process for the surface design of clockwork parts, characterized in that
that a film-forming lacquer is applied to the clockwork parts as a closed cover by electrophoresis in order to be able to form a mask for a surface design process by deliberately removing or changing the cover locally. Method according to claim 1,
characterized,
that the clockwork parts are subjected to at least one of the following process steps before the film-forming material is applied: Cleaning in an ultrasonic bath, preferably at temperatures between 50-90 ° C and particularly preferably at about 70 ° C; chemical deoxidation, in particular by the action of reducing agents and / or solvents for oxide layers; Cathodic, electrolytic degreasing, preferably at temperatures of 30-70 ° C, more preferably 40-60 ° C and particularly preferably at about 50 ° C, and / or preferably at currents of 200-500 A / m ² based on the surface the clockwork parts; and Neutralization and activation of the surface; in the case of the application of two or more of the steps mentioned, the specified sequence is preferably followed. Method according to one of claims 1 or 2, characterized in that
that the film-forming material is sensitive to an orientable form of radiation, in particular light, the film-forming material being selectively detachable at the irradiated points by irradiation and the clockwork parts covered with film-forming material being irradiated by an imaging method on the surfaces to be exposed for the formation of the mask. Method according to one of claims 1 to 3, characterized in that
that parts of the closed cover are removed from the film-forming material by the action of mechanical and / or thermal means and / or radiation, in particular lasers. Process for the surface design of clockwork parts which are covered with a cover covering the entire surface and leaving only the parts to be designed, this cover preferably being obtained according to the process according to one of Claims 1 to 4,
characterized,
that one or more of the following surface design processes are or will be used on the exposed areas: chemical ablation, in particular etching; electrochemical material removal; galvanic material application, in particular electroforming; Material application from the vapor phase, especially by chemical reaction (CVD) or in a physical way (PVD). Application of the method according to one of claims 1 to 5, characterized in that according to the method at least one galvanic coating of the surface takes place and preferably before and / or after the implementation of the Process a mechanical processing, such as grinding, Polishing and / or sandblasting takes place. Watch parts with surface design, in particular Inscription decorations that are raised or recessed are obtained according to one of claims 1 to 5 or Application of the method according to claim 6.

Images