METHOD FOR PRODUCING A CONTROL ELEMENT MADE OF PLASTIC WITH BACKLIT IMAGERY THAT IS METALLIZED ON ONE SIDE, CONTROL ELEMENT WITH BACKLIT IMAGERY, AND MACHINE FOR CARRYING OUT A PLURALITY OF METHOD STEPS

Abstract

A method for producing a control element made of plastic with backlit imagery that is metallized on one side, particularly for a motor vehicle, and a machine that is configured to carry out the aforementioned method, as well as to a control element with backlightable imagery.

Claims

1. A method for producing a control element made of plastic with backlit imagery that is metallized on one side, particularly for a motor vehicle, the method comprising: a. Producing a plastic base body with i. a sub-body made of a non-electroplatable plastic A that is arranged on the rear side and ii. an electroplatable layer of an electroplatable plastic B that is arranged on the front side, b. applying a filler composition to at least a portion of the electroplatable layer; c. forming the imagery through laser-lithographic processing of the applied filler composition in the regions forming the imagery; d. removing filler composition outside of the imagery from the electroplatable layer; e. depositing at least one metal layer on the electroplatable layer of the plastic base body through i. chemical deposition or ii. electrochemical deposition or iii. chemical or physical deposition of at least one electrically conductive metal layer and subsequent electrochemical deposition of at least one additional metal layer on the electrically conductive metal layer.

2. The method as set forth in claim 1, wherein a non-electrodepositable filler composition is used.

3. The method as set forth in claim 1, wherein a filler composition is used which comprises a resist that can cure under irradiation, for example a transparent or colored photoresist.

4. The method as set forth in claim 1, wherein the filler composition is applied over the entire surface of the electroplatable layer.

5. The method as set forth in claim 1, wherein the filler composition is applied at least on those portions of the electroplatable layer in which the imagery is formed.

6. The method as set forth in claim 5, wherein the filler composition is selectively applied in a desired portion of the electroplatable layer using an applied mask.

7. The method as set forth in claim 4, wherein the filler composition is imprinted, sprayed, rolled, or brushed onto the electroplatable layer.

8. The method as set forth in claim 4, wherein the filler composition is applied to the electroplatable layer by submerging the electroplatable layer into a receiver vessel filled with the filler composition.

9. The method as set forth in claim 1, wherein the laser-lithographic processing can be carried out with a pulsed laser.

10. The method as set forth in claim 1, wherein, during the laser-lithographic processing, a focused laser beam of the laser is guided over the filler composition along a predetermined travel path.

11. The method as set forth in claim 1, wherein the plastic base body with the filler composition applied to the electroplatable layer is moved relative to a positionally fixed-focus laser beam during laser-lithographic processing.

12. The method as set forth in claim 1, wherein a laser is used whose wavelength is adapted to the wavelength necessary for initiating a photopolymerization of the filler composition.

13. The method as set forth in claim 1, wherein the radiation emanating from the laser undergoes slight absorption in the plastic A and plastic B.

14. The method as set forth in claim 1, wherein the filler composition cures at least partially in the treated locations as a result of the laser processing.

15. The method as set forth in claim 1, wherein the filler composition undergoes a secondary curing process in the laser-lithographically treated locations after processing in which the curing is completed.

16. The method as set forth in claim 1, wherein the filler composition cures completely in the treated locations as a result of the laser processing.

17. The method as set forth in claim 1, characterized in wherein the filler composition that is outside of the imagery or not cured is removed from the electroplatable layer with the aid of a solvent.

18. The method as set forth in claim 1, wherein the filler composition that is outside of the imagery or not cured is removed by means of a CO.sub.2 spray system.

19. The method as set forth in claim 1, wherein the filler composition that is outside of the imagery or not cured is removed by pickling with a mordant.

20. The method as set forth in claim 1, wherein the edges of the laser-lithographically processed bodies are reworked after complete or partial curing thereof with a laser in order to impart a sharp contour to the imagery.

21. The method as set forth in claim 1, wherein steps b and c of the method according to claim 1 are carried out in a machine that is provided with a plurality of stations, method steps b and c each being associated with a station.

22. The method as set forth in claim 21, wherein the machine has an additional station in which step d of the method takes place.

23. The method as set forth in claim 21, wherein method step b is associated with a first station and method step c is associated with a second station.

24. The method as set forth in claim 21, wherein method step d is associated with a third station.

25. The method as set forth in claim 21, wherein method steps b, c, and optionally d are carried out with a turntable machine.

26. The method as set forth in claim 1, wherein, in order to chemically deposit the metal layer, a layer of palladium seeds is applied to the electroplatable layer.

27. The method as set forth in claim 1, wherein the applied palladium seeds are protected by a protective tin colloid layer.

28. The method as set forth in claim 1, wherein the protective tin colloid layer is removed before the chemical deposition of the metal layer.

29. The method as set forth in claim 1, wherein the surface of the electroplating layer to be electroplated is roughened, for example by chemical treatment, before the deposition of the metal layer.

30. The method as set forth in claim 1, wherein the plastic B is a transparent or translucent polyamide, ABS, or an ABS/polycarbonate blend.

31. The method as set forth in claim 1, wherein the plastic A is a polycarbonate.

32. A control element with backlightable imagery, particularly for a motor vehicle, produced by means of a method as set forth in claim 1, comprising a plastic base body with a sub-body made of a non-electroplatable plastic A that is arranged on the rear side and an electroplatable layer of an electroplatable plastic B that is arranged on the front side, the imagery being formed by a filler composition that is applied to the electroplatable layer and processed by means of laser lithography, and at least one metal layer being deposited on the electroplatable layer.

33. A machine for carrying out at least method steps b and c of the method as set forth in claim 1, comprising: a station for applying a filler composition to at least a portion of the electroplatable layer and a station for forming the imagery through laser-lithographic processing of the applied filler composition in the regions forming the imagery.

34. The machine as set forth in claim 33, wherein an additional station in which the filler composition outside of the imagery is removed from the electroplatable layer.

35. The machine as set forth in claim 33, wherein the machine is a turntable machine.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0093] An advantageous embodiment of the method according to the disclosure will be explained in more detail in the following with reference to the accompanying drawing, in which

[0094] FIG. 1 shows a schematic illustration of the process flow of the method according to the disclosure;

[0095] FIGS. 2a-d show a schematic illustration of method steps c and d according to a first embodiment of the method on which the disclosure is based; and

[0096] FIGS. 3a-c show a schematic illustration of method steps c and d in a second embodiment according to the method on which the disclosure is based.

DETAILED DESCRIPTION

[0097] As shown in the schematic process diagram of FIG. 1, a sub-body made of a non-electroplatable plastic A (polycarbonate, for example) is produced in method step 1 by means of injection molding in an injection mold. The shape of the cast plastic is essentially defined by the mold, more particularly the cavity. In addition, other components can be placed into the mold against which the plastic composition A is cast.

[0098] In method step 2, an electroplatable layer of an electroplatable plastic B (e.g., ABS/polycarbonate blend) is injection-molded against the front side of this sub-body, whereby the base body of the control element according to the disclosure is formed as a two-component (2K) component. Method steps 1 and 2 can also be carried out in reverse order.

[0099] In the subsequent optional method step 3, at least the surface of the electroplatable layer of the control element undergoes a pickling process in which the butadiene fractions are eluted out of the surface of the ABS plastic part. This process step is preferably carried out in a chromosulfuric acid bath. Besides roughening the electroplatable surface of the plastic control element, contaminants, among other things, are removed from the electroplatable surface, particularly any adhered organic contaminants. This method step can be repeated after method step 5 or, in principle, represent method step 6.

[0100] According to method step 4, a filler composition is applied to the electroplatable layer of the plastic base body. The filler composition can be applied by imprinting, brushing, rolling, spraying, or by means of a dipping technique. The filler composition can be a paint, e.g., a UV paint, that comprises additional components such as particles for absorbing laser beams, for example.

[0101] In the illustrated method step 5, the imagery is formed, namely by laser-lithographic processingalso called laser writing. In the regions forming the imagery, i.e., those areas in which certain symbols are to be provided, a laser beam (preferably a UV laser) is moved over the filler composition along a predetermined path. In this case, the filler composition can cure completely or to a large degree. The laser can initiate photopolymerization in the filler composition and/or accelerate the curing through heat input, for example. After (partial) curing, uncured filler composition is removed according to method step 7, for example by washing or a pickling process.

[0102] For the sake of example, FIGS. 2a to 2d show the process of laser writing and the removal of the uncured filler composition. As illustrated in FIG. 2a, a filler composition 2 has been applied to the electroplatable layer 1 prior to laser-lithographic processing. In the present example, the electroplatable layer 1 is coated over its entire surface with the filler composition 2. In those regions of the filler composition 2 in which the imagery is to be formed, a laser beam 3 is moved over the filler composition 2 along a predetermined path (FIG. 2b). In the lateral direction, a region of the filler composition 2 corresponding to a writing width 4 of the laser beam 3 is exposed by means of the laser beam 3 to the laser radiation 3 or processed by the laser. The laser beam 3 can be moved multiple times along the same path. If the focus of the laser beam 3 is smaller than the desired writing width 4, then the laser beam 3 can be moved multiple times along mutually parallel paths in the lateral direction. As a result of the action of the laser beams 3, the filler composition 2 cures at least in the region of the writing width 4 of the laser and forms a cured region 5. After the uncured filler composition 2 has been removed, the cured region 5 remains on the electroplatable layer 1 and is raised in relation to the regions 6 that have been washed out or freed of filler composition 2 (FIG. 2d). The cured region 5 thus forms the imagery.

[0103] FIGS. 3a to 3c show a process that has been slightly modified in comparison to the process illustrated in FIGS. 2a to 2d. Instead of direct laser writing, the cured region 5 of the filler composition 2 (see FIG. 3b) is formed with the aid of a mask 7. The mask 7 is composed of a material that is impenetrable to the laser beams 3. As shown, however, the mask 7 has at least one opening 8 through which laser radiation 3 can pass in the direction of the filler composition 2. No positionally precise displacement of the laser beams 3 is required in this variant. However, in addition to the uncured filler composition 2, the mask 7 must also be removed from the substrate after the laser treatment. As shown in FIG. 3c, after the mask 7 is removed, imagery or a cured region 5 remains that is raised with respect to the regions 6 that have been washed out or freed of the filler composition 2.

[0104] After the laser-lithographic curing, a secondary curing process can take place.

[0105] Returning to the schematic process diagram of FIG. 1, the edges surrounding the imagery can undergo secondary processing in a method step 7 with one or more lasers in order to form clear outlines of the imagery. Excess filler composition is removed or lasered away.

[0106] In method step 8, the electroplatable surface of the base body is activated, i.e., the surface is seeded in a manner known from the prior art with palladium seeds from colloidal solution, the palladium seeds preferably being covered by a protective tin colloid. The protective tin colloid is removed by washing to form a surface with active palladium.

[0107] In method step 9, an electrically conductive first metal layer is applied to the activated surface of the base body by chemical means, i.e., without the use of an electroplating current. For this purpose, the base body is introduced into a suitable nickel bath, from which nickel is deposited on the activated surface of the base body (so-called chemical nickel). The resulting thin nickel layer has a thickness of about one micrometer. The nickel layer represents the (first) deposited metal layer.

[0108] In an alternative variant of the method, the electroplatable surface of the base body is activated in method step 8athat is, the surface is seeded with palladium seeds from colloidal solution, the palladium seeds preferably being covered by a protective tin colloid. This is replaced by copper in an alkaline solution in a method step that is not shown. The resulting copper layer offers a sufficiently high coverage and thus electrical conductivity in order to be electrochemically galvanized without additional intermediate steps (such as the deposition of chemical nickel/chemical copper, for example). This procedure is also referred to as direct metallization.

[0109] Furthermore, it is known that the sequence of the method steps that are not shown in the figuresourcing the plastic (ABS, ABS-PC, PC, PES, PEI, PEEK, etc.), pickling in an oxidizing solution (chromosulfuric acid, potassium permanganate, etc.), activation in a metal complex-containing solution, crosslinking by forming metal sulfides in an alkaline sulfide solution and, finally, electrochemical plating in a metal bathmakes it possible to dispense with a time-consuming electroless deposition of chemical nickel or chemical copper.

[0110] In optional method step 10, the layer thickness of the thin nickel layer is increased by several 100 nanometers through electrochemical deposition of nickel or copper at low current in order to increase the conductivity and/or current-carrying capacity of the first metal layer (nickel precursor, copper precursor).

[0111] In the next method step (not shown), the base body that is covered on the electroplatable surface with the first metal layer (i.e., a thin nickel layer and, optionally, a layer of nickel precursor or copper precursor) is removed from the electroplating process, washed, and dried.

[0112] The base bodies are then fed to the electroplating process. Here, in the next method step 11, a first metallic intermediate layer is electrodeposited in a first (or, if copper precursor or nickel precursor was applied: second) electrochemical electroplating step. This is usually made of copper and has a thickness of typically between 10 and 40 micrometers. This electroplating step is preferably carried out in such a way that a minimum layer thickness of the first copper intermediate layer of 20 micrometers is achieved regardless of the position of a control element on the holder.

[0113] In the subsequent method steps 12 and 13, a second intermediate layer of nickel is electrodeposited on the first intermediate layer of copper. This can be embodied as a single layer of matte nickel with a thickness of at least 10 micrometers. Alternatively, the second intermediate layer can also be embodied as a successions of layers of bright nickel, semi-bright nickel, matte nickel, microporous nickel, and/or cracked nickel. For example, a layered structure composed of about 5 micrometers of semi-bright nickel on which a layer of matte nickel or bright nickel (depending on the desired appearance of the finished metallized surface) with a thickness of about 5 micrometers is applied has been found to be advantageous in practice. This layered structure has a high corrosion resistance due to the positive properties of semi-bright nickel. If the metallized control elements are intended for use in a highly corrosive environment, then it has proven expedient to use at least one intermediate layer of cracked nickel, particularly a succession of layers of semi-bright nickel, bright or matte nickel, and cracked nickel for the second intermediate layer.

[0114] Finally, in method step 14, a layer of a decorative metal, which can be chromium, for example, is electrodeposited on the second intermediate layer of nickel. Typical layer thicknesses of this decorative layer are between 100 nanometers and a few micrometers, and preferably at least 300 nanometers in the case of chromium.

[0115] Optionally, after removal of the base body from the electroplating, which is followed by a cleaning and a drying step (not shown in the figure), a colorizing of the metallized surface can be performed in an additional method step (not shown) by means of PVD methods. In that case, a metal layer of gold, for example, with a thickness of between 100 nanometers and a few micrometers is applied. A wide range of colors can be achieved here.

[0116] Finally, in a final method step (not shown), a layer of lacquer can be applied which, for example, can alter or improve the appearance of the metal layer that is applied on the front side and/or the corrosion resistance thereof.

[0117] As will readily be understood, the method according to the disclosure can also be carried out without individual method steps illustrated in FIG. 1. For example, if steps 8 to 10 are omitted, then this is a method variant according to step e, ii of patent claim 1that is, the purely electrochemical deposition of at least one metal layer. Even a purely chemical deposition of at least one metal layer is conceivable.

[0118] The present disclosure is not limited to the exemplary embodiment that has been illustrated and described. Modifications are also possible within the scope of the claims, as is a combinations of the features, even if these are illustrated and described in different exemplary embodiments.