EP2835446A1 - Metallisation method with protective layer - Google Patents

Abstract

The invention relates to a method for metallizing a component surface, wherein after a sulfonation for preparation, a protective layer is deposited on a part of the surface and then a nucleation and subsequent metallization is carried out on the part not covered by the protective layer.

Description

The present invention relates to a method for metallizing a component surface.

Methods for metallizing component surfaces are used extensively. An example to which the present invention is also preferably directed is the metallization of plastic components, in particular vehicle interior components. It may be z. B. act delusions or buttons in a car. Often, a metal surface is desired here for aesthetic reasons or to improve the cleaning properties or for other reasons.

The invention is based on the object of specifying in such a metallization a simple way to exclude a certain part of the surface of the metallization.

1. 1) Sulfonieren der Oberfläche zur Vorbereitung einer Bekeimung,
2. 2) Abscheiden einer auf einen Teil der Oberfläche begrenzten nicht metallischen und nicht leitfähigen Schutzschicht,
3. 3) Bekeimung der sulfonierten Oberfläche mit einem Metall, insbesondere Palladium, wobei die Bekeimung wegen der Abdeckung durch die Schutzschicht nicht auf dem von der Schutzschicht eingenommenen Teil der Oberfläche erfolgt,
4. 4) chemische Abscheidung einer Metallschicht auf der bekeimten Oberfläche, wobei auch die chemische Abscheidung nicht auf dem von der Schutzschicht eingenommenen Teil der Oberfläche erfolgt.

The solution is a procedure with the following steps:

1. 1) sulfonating the surface to prepare a germination,
2. 2) depositing a non-metallic and non-conductive protective layer bounded on a part of the surface,
3. 3) seeding of the sulfonated surface with a metal, in particular palladium, whereby the germination does not take place on the part of the surface occupied by the protective layer because of the covering by the protective layer,
4. 4) chemical deposition of a metal layer on the germinated surface, wherein also the chemical deposition does not take place on the part of the surface occupied by the protective layer.

In the metallization of the present invention, the surface (usually cleaned) is prepared for nucleation by sulfonation (optionally followed by a rinsing step), e.g. for a known seeding with palladium. The area to be kept clear is then covered with a protective layer that is non-metallic and non-conductive. In this case, "non-conductive" denotes the absence of a metallic conductivity; It is about preventing a subsequent metallization in a preferred subsequent galvanic process.

As a result of the protective layer, part of the surface is not accessible to germination. In addition, in many cases, even on the protective layer, there will be no seeding, at least not germination comparable to the rest of the surface, because the sulphonation pretreatment is lacking.

After seeding, a metal layer is then deposited by means of a chemical process, that is, without external current. This metal layer may separate selectively, ie not on the protective layer, because there, as I said, there is no or no equivalent germination. Even if it deposits on the protective layer, it can later be removed with the protective layer. Typical layer thicknesses are 0.1 to 1 μm.

In many cases, one will reinforce the chemically deposited layer, preferably by a galvanic metallization of a few to a few tens of microns. Preferred examples are a chemical nickel layer and thereon e.g. a galvanic nickel layer and possibly a final chrome layer.

For the germination, a treatment with palladium ions is preferred, ie in particular no seeding with colloidal palladium.

In many cases, practically suitable protective layer materials dissolve in the chemical metallization step or at the latest in the galvanic metallization step. However, suitable cleaning steps can also be included. It has proven useful to deposit the protective layer using a printing process. Concretely, for example, an inkjet printer can be used become. The printer ink already forms a suitable protective layer. The process according to the invention works particularly well on plastic components, preferably on those whose plastic has double bonds. These double bonds are good sites for sulfonation. For sulfonation is treated in gaseous sulfur trioxide, for example with oleum (fuming sulfuric acid). A preferred group of materials are the polyaryl plastics.

Preferred field of application of the invention is the consideration of windows in the component, in particular for visible light, in special cases but also for infrared radiation. Then, e.g. a light signal or a light source for illumination or a sensor functioning with corresponding radiation use the corresponding translucent window.

For this purpose, the plastic may have a glass fiber portion for mechanical reinforcement and to improve the translucency (wherein translucency basically includes the transparency). Preferably, the glass fiber content is at least 50 percent by weight. In this form, different material thicknesses are conceivable, from quite thin covered by the metallization and kept free through the window wall sections with a thickness in the tenth of a millimeter range up to a few millimeters. A particular advantage lies in the fact that, especially with a glass fiber reinforcement, thick (and therefore stable) materials with thicknesses of more than 2 or even more than 3 mm are possible.

The plastic component coated in accordance with the invention may in particular also be a two-component injection-molded component in which one of the injection-molding operations has produced a transparent or generally translucent plastic window in a component which is otherwise designed according to criteria other than translucency. In the translucent area then a window according to the invention can be arranged.

Regardless of the translucency, the part of the surface covered by the protective layer can also form an opening in a planar metallization, that is to say an opening in an all-round and in comparison to the one Dimensions of the opening significantly larger area metal layer. Such an opening can also serve for aesthetic design or leave a lying below the metal layer material for other reasons.

In the manufacturing process, the application of the protective layer prior to seeding is also advantageous because the process can thus be carried out particularly simply. In particular, the parts can be hung on a conventional galvanic rack and remain, so go through the various stages of the process (such as in the claims so numbered steps 3 to 5 and if necessary further) without further changing or remounting. For the sulfonation, however, another frame is advantageous anyway, which is why a subsequent capping can hardly be avoided here. In that regard, the application of the protective layer according to the invention produces no significant additional expense.

The invention relates, as explained above, to a manufacturing method, but also to a finished vehicle interior component or another manufactured product, in whose production, inter alia, the inventive method has been applied, with a further processing is not excluded. The invention also relates to the use of a sulfonated and partially covered with the protective layer according to claim 1 component for metallizing according to claim 1, that is, by seeding and subsequent chemical deposition. The various features and retraction positions should also be disclosed for this purpose.

In the following the invention will be explained in more detail with reference to an embodiment.

In a manner known per se, a switch or pushbutton for a motor vehicle interior is produced in a two-component injection molding process. This component consists of glass fiber reinforced polyaryl plastic with a glass fiber content of 60 percent by weight and a translucent part.

This component to be coated is first cleaned and then sulfonated in gaseous sulfur trioxide for one minute. Basically, treatment times of between 10 seconds (preferably 20, 30, 40 or 50 seconds) and 10 minutes (preferably 9, 8, 7, 6 or 5 minutes) make sense for the sulfonation.

The sulfonated surface is first rinsed with water and then printed in the translucent portion with an ink jet printer, the ink jet printer, under the control of a computer, printing a particular symbol corresponding to the button actuated function in the vehicle, e.g. a seat heating symbol. The printer ink stops processing and protects the underlying sub-surface from the next steps.

This is followed by seeding in an ionic palladium solution. In this case, palladium ions are deposited on the surface and can be reduced in a subsequent reducing solution to metallic palladium nuclei.

The palladium nuclei can then deposit a nickel layer in a conventional chemical nickel deposition step. This is again reinforced with nickel in a second galvanic step. Subsequently, a so-called acidic copper layer can be electrodeposited and finally the component can be galvanically covered with a chromium layer.

Experience has shown that the printer ink already dissolves during the chemical nickel step and at the latest at the galvanic nickel step. Since there is no metallic base in the surface part covered by the ink and no conductivity is given, the remaining metal layers do not separate there but remain a neatly defined window. Through this window, e.g. the light of an LED indicates the operating state of the switch, e.g. light up when the seat heating is switched on.

In principle, however, a sensor operating in the visible or infrared range behind the window would also be conceivable in the same form, or even viewing a more complex display as a simple luminous symbol.

During the sulfonation step, the component hangs with other type-like components in a stainless steel frame and is then transferred after printing in a PVC-coated electroplated rack. In this, it remains for the remainder of the process up to and including the chrome coating, so that the printing step insignificantly complicates the metallization process.

Claims (15)

A method of metallizing a surface of a component, comprising the following steps in the following order: 1) sulfonating the surface to prepare a germination, 2) depositing a non-metallic and non-conductive protective layer bounded on a part of the surface, 3) seeding of the sulfonated surface with a metal, in particular palladium (Pd), whereby the germination due to the covering by the protective layer does not take place on the part of the surface occupied by the protective layer, 4) chemical deposition of a metal layer on the germinated surface, wherein also the chemical deposition does not take place on the part of the surface occupied by the protective layer. The method of claim 1, wherein step 4) follows: 5) Galvanic deposition of a metal layer on the chemically deposited metal layer. A method according to claim 1 or 2, wherein the Pd nucleation is carried out with ionic Pd and the deposited Pd ions are chemically reduced following and before the chemical deposition of the metal layer in step 4). Method according to one of the preceding claims, wherein in step 4) a nickel layer is deposited. Method according to one of the preceding claims, in which the protective layer is deposited in step 2) by a printing process. The method of claim 5, wherein the protective layer consists of printing ink. Method according to one of the preceding claims, in which the protective layer dissolves in the chemical deposition in step 4) and / or in the electrodeposition in step 5). Method according to one of the preceding claims, wherein the component consists of a plastic, in particular a plastic having a polymer structure having double bonds, preferably a polyaryl plastic. The method of claim 8, wherein the plastic is glass fiber reinforced, in particular with a glass fiber content of at least 50 weight percent. Method according to claim 8 or 9, wherein the component in the part of its surface covered by the protective layer has a thickness perpendicular to the surface of between 0.1 mm and 10 mm. Method according to one of the preceding claims, in which the part of the surface covered by the protective layer after removal of the protective layer and after step 4) is or belongs to a translucent part of the component. Method according to one of the preceding claims, in which the part of the surface covered by the protective layer and after step 4) is an opening in a planar metallization on the surface. Method according to one of the preceding claims, in which, after the sulfonation in step 1, all further steps are carried out when the component is attached to one and the same electroplating rack. Method according to one of the preceding claims, in which a vehicle interior component is produced. An interior vehicle component comprising a metal layer made by including a method according to any one of the preceding claims.