WO2012022660A1

WO2012022660A1 - Process for the electroless copper plating of metallic substrates

Info

Publication number: WO2012022660A1
Application number: PCT/EP2011/063752
Authority: WO
Inventors: Michael Kleinle
Original assignee: Chemetall Gmbh
Priority date: 2010-08-17
Filing date: 2011-08-10
Publication date: 2012-02-23
Also published as: US20130143071A1; EP2606162A1; MX2013001838A; DE102011080745A1; MX344173B; BR112013003430A2

Abstract

The invention relates to a process for treating a metallic surface of an object with an aqueous copper-plating solution, with which a first copper-plating solution, which is free of cyanide and free of strong reducing agent, is electrolessly applied to clean metallic surfaces of the object, or after pretreatment to cleaned metallic surfaces, to form a first copper layer or copper alloy layer as a barrier layer and/or as a conductive layer, and also to the use of the objects produced by the process according to the invention.

Description

METHOD FOR ELECTRICALLY PROCESSING METALLIC COPPER

SUBSTRATES

The invention relates to methods of treating a metallic surface of an article - in particular for treating the metallic surface of an article having a surface of a ferrous material, of a zinc material or / and of a tin material, e.g. from zinc and / or from a zinc alloy - with an aqueous copper plating solution for applying a copper layer as a barrier layer and / or as a conductive layer, in particular for simpler, less expensive and more environmentally friendly processes. However, the article may also consist of at least one non-metallic or / and at least one metallic material, which is provided with at least one metallic layer.

Plating in metalworking refers to the application of a metal layer of a more noble metal to another metal of lower potential, for example by rolling, welding, casting, spraying or / and dipping. If galvanic processes are used, the expert speaks of electroplating.

Galvanizing is a significant technology for protecting and refining metallic and other objects. The galvanic treatment includes any type of electrolytic treatment, that is, coating or / and treating a metal in an aqueous solution under electric current flow. These may be, for example, copper plating, spattering, nickel plating, cadmium plating, chrome plating, lead plating, silver plating, rhodium plating, platinizing or gold plating. In many cases, copper plating, nickel plating, chrome plating, silver plating or gold plating are used. Often, several successive galvanic layers result. On a nickel can then, for example, a chrome plating, silvering, Platinieren, rhodium plating and / or gilding consequences. Only in rare cases, there is only a single cover layer of copper. In almost all cases, at least one nickel covering layer follows today on a copper cover layer. In almost all cases, today at least one different cover layer, such as at least one covering layer of gold, platinum, rhodium, silver or chromium, follows on a nickel covering layer, whereby all covering layers are usually applied electrolytically and mostly from acidic aqueous solutions. The cover layers may comprise, for example, bright copper layers with layer thicknesses usually in the range from 3 to 50 .mu.m and preferably in the range from 5 to 20 .mu.m, thick copper layers having layer thicknesses usually in the range from 50 to 5000 m, and preferably in the range from 80 to 500 .mu.m, bright nickel layers Layer thicknesses usually in the range of 3 to 20 pm or / and thick nickel layers with layer thicknesses usually be in the range of 30 to 250 pm. If no external power source is used as the supplier for the electrons required in the metal deposition, and this plating is carried out without containing a strong reducing agent, the person skilled in the art will speak of electroless plating, coating or treatment. The addition and use of at least one strong reducing agent to the bath used without electrical current means that the electrons necessary for the metal deposition are supplied by at least one strong reducing agent present in the bath, which is then referred to as chemical or electroless plating, coating or treatment. The terms "chemically copper" and "chemically nickel" also mean that at least one strong reducing agent is used in the bath.

Weak reducing agents are not used in electroplating for metal deposition because they do not achieve the potential required for deposition, because a chemical (= electroless) copper bath or a chemical nickel bath does not work with weak reducing agents alone. All reductants used in chemical copper or nickel baths therefore, they have a potential with values of at most -0.6 V or preferably of at most -0.8 V and particularly preferably of at most -1 V. The data on the potential relate to measurements with a standard hydrogen electrode. And these reducing agents are considered to be strong reducing agents, ie have potential values of at most -0.6 V and often values in the range of -3 to -1V.

Electroless baths are usually the galvanic = electrolytic o- / / and the electroluminescent = chemical = strong reducing agent containing baths preferable because they lead to a faster layer formation at a lower workload and a lower energy consumption than in electrolytic and electroless baths, so far Such layers can be formed without power at all. However, in many cases the desired metal layers of suitable layer quality can only be produced electrolytically, e.g. in an alkaline, cyanide electrolytic copper plating, in an alkaline, cyanide-free electrolytic copper plating or in an acid electrolytic nickel strike process. Therefore, today almost always electrolytic, d. H. energetically and technically very complex, worked because no suitable electroless and usually no suitable electroless plating process are known.

All of the baths mentioned here and below are aqueous compositions, which is why water is not always mentioned in concrete compositions. A copper plating or nickel plating bath contains the aqueous copper plating or nickel plating solution. In many cases, a barrier layer on the surface of a workpiece is necessary if it has a base metal in order then to be able to be further processed electrolytically in an aqueous medium. A barrier layer is required, for example, to cause an uncontrolled, generally poorly adhering deposition on the workpiece, for example with a surface of one To avoid metal with more electronegative potential than copper from a solution with higher potential. Treating a workpiece with a surface such as iron, an iron alloy, zinc and / or a zinc alloy in a sulfuric acid copper sulfate solution, which corresponds to the gloss and / or Dickschichtverkupferung of the prior art and is applied electrolytically by various Galvanofachfirmen, so go iron or / and analogously, for example, zinc after the redox reaction

Oxidation: Fe Fe ²⁺ + 2e ^"

Reduction: Cu ²⁺ + 2e ^" Cu with electron donation in solution Then, metallic copper precipitates on the surface in a non-stick coating, because so far only very thin, spongy, porous, hardly to not adhering layers can be deposited , the use of such layers for further processing in the decorative or functional field of electroplating is out of the question.

Without applied barrier layer therefore takes place in acidic electrolytic copper plating baths a disturbing pickling attack on the clean or cleaned metallic surface. The pickling attack then sets off the south deposit. In this case, in particular iron or / and zinc ions are leached out of the object to be coated. They go into solution. As a result, electrons are released, which in turn are absorbed by the ions of the subsequent acidic plating bath. The corresponding metals are deposited as non-adherent cementation on the base material. In part, this pickling attack also leads to the destruction of the base material. As a result, however, the subsequent plating baths are polluted. Registered impurities, optionally including foreign ions, are deposited uncontrolled during electrolysis and preferably in the range of low current density as metal precipitation. They cause dull, gray, streaky, rough or / and po Roughened layers which are not suitable for further processing, in particular in the technical or decorative field. The foreign substances introduced into the bath can only be removed by selective cleaning, partial scraping or throwing of the galvanizing bath. If the non-adhering precipitate formed by cementation in the subsequent plating baths is broken down, for example as a result of the movement of the articles or / and the bath, the precipitated metal is likewise partially re-incorporated into the layer to be deposited. It causes significant defects, pores, roughness and / or elevations. Such metal crumbs can only be removed by very intensive filtering. In principle, the entry of foreign substances into the subsequent plating bath will result in process disruptions, losses in quality, additional costs and / or additional expenditure, regardless of whether the foreign substances are present as ions, as metallic crumbs and / or as thin skins. A barrier layer is used to coat workpieces of any part geometry from a base material with a low electrochemical potential such as iron, zinc, tin or / and one of their alloys, to pickle attack and destruction on the base material, carryover of foreign ions in the galvanic Bad, contamination of the successor baths, Sudabscheidung, non-adherent, vapourous or porous layers and subsequent coating defects such as dull, gray or streaky layers to avoid.

Barrier layers of copper or nickel prior to further galvanic treatment are known in principle. Baths with which such barrier layers are produced are also called stop baths by the person skilled in the art.

To date, for the production of a barrier layer in industrial practice, either 1) a cyanidic, alkaline, electrolytic copper plating bath, 2) an alkaline, complexing agent-containing electrolytic copper bath or 3.) used an acidic electrolytic nickel strike bath. Preferably, in more than 85% of cases, a cyanide-containing alkaline electrolytic copper plating bath 1) is used in industrial practice in Central Europe. At least one metal coating of a metal having a higher potential than the base material of the original metallic surface can then be applied electrolytically directly to the copper or nickel barrier layer formed in these baths. This can then be at least one metal or / and at least one alloy coating such. B. based on Cu, Ni, Cd, Cr, Ag, Au, Rh and / or Pt, the copper over a copper plating, nickel plating, Vercadmung chrome plating, silver plating, gold plating, rhodium plating or / and platination in particular from acidic, cyanide-free and Reductant-free electrolyte is applied electrolytically, for example, as at least one gloss and / or as at least one thick film. The barrier layers should have excellent adhesion to the base material of the substrate, a high ductility and a high degree of purity and should be free of pores. However, this succeeds only partially in the case of a content of foreign substances in the bath. In addition, at least one subsequent surface treatment such as electroplating, painting, coating with a powder coating or with a cathodic dip coating (KTL) or joining with another object should be made possible in each treatment stage.

In addition to the purposes generally described above, a copper blocking layer according to the invention also serves workpieces of any partial geometry and optionally also with cuts and backstitches made of a base material with a low electrochemical potential, such as iron and / or zinc and / or one of these Alloys, environmentally friendly, de-energized and high quality and cost-effective, effective and fast to coat the corresponding process of the state of the art. When applying a barrier layer and preventing sedimentation, it is therefore still necessary today, and even before further electroplating, to workpieces which are made of a material with a very low potential and, in particular, decorative or technical, first electrolytically ie using current, with a coating of a cyanidic alkaline electrolyte 1.) or rarely instead of a pure alkaline complexing agent-containing bath 2.) to coat. Since the metal deposition takes place from a metal-cyano complex in 1) or 2), for example, from a phosphorus complex, which has extremely high internal molecular binding forces, a sedimentation is avoided when immersing the part to be coated in the bath. Under Sud here is an uncontrolled electroless deposition of copper, nickel and / or other metals understood by electron exchange. This uncontrolled electroless or electroless deposition usually results in non-adherent or poorly adhering precipitates that are powdery, porous, gritty (= rough, grainy, and removable), and / or grainy.

A conductive layer is a layer which is used to increase the electrical conductivity of an object, as it has on its own. For example, a thin layer of copper deposited on a steel wire can reduce its contact and / or line resistance by up to 20 times. This is used, for example, to reduce the electrical line resistance in the welding wire production o- to reduce the contact resistance in connectors in the electronics sector.

In acidic copper baths, the bath constituents usually decompose into the corresponding ions. Therefore, in acidic copper baths, a base material of more electronegative potential than copper can not be copper-plated without electricity and also not with electricity, since the nobler metal acts as a brew in of a non-adhesive layer on the base material. A deposited by beating copper layer is not commercially applicable.

In cyanide alkaline copper baths as in 1.) The copper cyanide complex is so stable that it does not decompose into ions. Therefore, a base material of more electronegative potential than copper can not be electrolytically copper plated without power, but in several process variants. For this reason, electrolytic copper baths are usually used in alkaline cyanide for applying a barrier layer or conductive layer.

These cyanidic, alkaline electrolytic processes are today process-safe and manageable. An electrolytic coating process always requires more effort than an electroless plating process. They are due to the metal deposition under high power consumption and due to the heating of the electrolyte to often 60 to 85 ° C energetically consuming. Cyanide-containing baths are highly toxic, dangerous and environmentally unfriendly. Therefore, they require separate waste water handling and treatment as well as certain storage conditions. It is not uncommon for fatal work-related accidents to occur occasionally due to the cyanide content.

Instead of the highly toxic, dangerous and environmentally unfriendly cyanide complex, there are many attempts to use less harmful complexing agents and complexes for coppering baths. Weak complexes such as e.g. a citrate, hydroxo, ammonium, acetate, phosphate and diphosphate complex decompose in acidic and alkaline solutions. Strong complexes such as e.g. Ethylenediaminetetraacetate (EDTA) are stable in acidic and alkaline solutions, but are environmentally unfriendly because of their risk of wastewater. They are therefore rarely used commercially.

The most important baths and coating processes of the prior art used in this case are described below: 1.) Cyanide Electrolytic Copper Plating: Usually, in more than 85% of cases, these barrier layers are still made of cyanide alkaline copper plating electrolytes today, especially for the basic materials iron, zinc or their alloys applied. Their aqueous compositions and treatment conditions are often as follows:

The copper plating bath contains about 50 g / L CuCN, about 75 g / L NaCN, about 40 g / L NaOH and, if necessary, gloss-forming additives, but usually no reducing agents and no acid. Its pH is about 12. It is worked at about 40 ° C and at a current density of about 1 A / dm ² for about 10 minutes

Metal deposition takes place according to the following equations: [Cu (CN) ₃ ] ² - [Cu (CN)] + 2CN ^"

[Cu (CN)] + e ^" (from external power source, rectifier) Cu + CN ^"

However, such cyanide-containing alkaline electrolytic copper plating baths may also be used to alter the technical properties of a base material for particular uses, e.g. for the production of a barrier layer prior to nitriding steel or for the production of a layer with lower electrical resistance, as e.g. for a conductive heating of workpieces such as e.g. Screws is needed. The advantage here is a better corrosion protection o- / and better electrical conductivity than the base material has of its own.

A disadvantage of the cyanide-containing baths is that they are problematic because of their toxicity and hazardousness for wastewater, the environment and disposal that they must be heated to at least 50 ° C and that necessary for metal deposition electrons through an external rectifier (= energy-intensive ) must be delivered. 2.) Cyanide-free, alkaline, electrolytic copper plating: Cyanide-free, alkaline baths are not highly toxic. In cyanide-free alkaline copper baths, the bath components usually also do not decompose into the corresponding ions. Therefore, a base material of more electronegative potential than copper can not be de-energized, but can only be copper-plated with difficult process control and after critical pretreatment with electricity. Therefore, nowadays electrolytic copper baths are occasionally used alkaline cyanide-free for the application of a barrier layer. However, the pretreatment of the base material as well as the process control are therefore much more critical or expensive than with 1). So far, not all base materials could be treated with it. Great care should be taken in the pretreatment of the workpieces.

Their aqueous compositions and treatment conditions are often as follows: The copper plating bath contains about 15 g / L Cu, about 50 g / L pyrophosphate, dilute KOH or H ₃ P0 ₄ if necessary to adjust the pH to about pH 9 and if necessary gloss-forming additives. It may sometimes be free of reducing agent, free of pickling agent and / or free of acid. It is used at least 60 ° C and at about 1 A / dm ² current density over about 10 minutes.

A disadvantage of the cyanide-free, alkaline, complexing agent-containing baths is that their process management is very critical, that their bath parameters are to be kept very tight, that their pre-treatment has to be carried out carefully and that the input of foreign substances is critical. If foreign substances are introduced as an impurity in the bath, they are deposited in the layer to be deposited and impair their quality. These barrier layers can then be schlierig, gray, matte and / or porous, but then are no longer necessarily closed, fine crystalline, non-porous, ductile and well-adherent. Remedy could only create a Verwurf or Teilverwurf and new approach of the bath. In addition, parts made of die-cast zinc can not because of their poor conductivity in the galvanic drum process, but only galvanically coated in the complex frame process. In addition, these baths are again to temper at least 60 ° C. The electrons required for metal deposition are also supplied by an external rectifier (= energy-intensive).

3.) Electrolytic, galvanic nickel strike bath: For workpieces made of iron and / or their alloys, so-called nickel strike baths are also used today for applying a barrier layer.

Rarely, in about 3% of cases, are nickel strike baths used today for barrier layers in industrial practice, in particular for the basic materials iron or their alloys. Their aqueous compositions and treatment conditions are often as follows:

In addition to at least one nickel compound, they always contain acid and often at least one brightener. If appropriate, they contain, for example, NaCl as pickling booster and / or, if necessary, luster-forming additives. They are usually free of alkalis and reducing agents. Depending on the base material, they often operate at concentrations of 200 to 250 g / l NiCl ₂ and from about 200 g / l HCl at pH values below 0.5 or at concentrations of 200 to 250 g / l NiCl ₂ and of about 40 g / LH ₃ B0 ₄ at pH's of about 4 at about 40 ° C for about 5 minutes.

A disadvantage of such nickel strike baths is that it comes here by the very high proportion of chloride to a strong pickling attack on the base material, whereby its embrittlement can hardly be avoided and where it sometimes comes even to the destruction of the base material. In addition, the strong corrosive effect of chlorides affects the entire system and the entire building. The sulfamate stop baths, which are sometimes used as an alternative, can reduce the high level of corrosion around the baths due to the lower chloride content However, the corrosion does not completely prevent. In addition, it is imperative to extract the gases above the baths due to the possibility of chlorine gas formation. The baths are due to the entrained impurities, optionally including foreign ions, continuously clean eg by filtering to remove foreign substances such as metal particles. By the pickling attack on the base material foreign substances are registered. In this case, in these baths, it is also necessary to operate selectively with lower electric currents than required for the deposition of the noble metal in order to deposit the dissolved foreign substances, including foreign ions, on the object to be coated and to thereby clean the bath. Alternatively, discard a dirty bathroom.

4.) Although no barrier layer can be produced with an acidic glaze or thick copper plating, it is used to form high-quality copper layers. It has long been used in electroplating, in particular for the production of decorative and / or electroformed coatings used. However, workpieces made of a base material with more electro-negative potential than copper without a barrier layer can not be treated due to the onset of sebum deposition therein.

Bright nickel plating can only be carried out electrolytically in an acidic bath. Bright copper plating can only be carried out electrolytically in an acidic bath. A much more uneconomical alternative to this could be a cyanide alkaline electrolytic copper plating 1) serve. However, the coppered articles must then be polished by hand or by machine to achieve the required gloss. As an even less economical alternative could be a cyanide-free, alkaline, complexing agent-containing copper plating 2.) serve, in which the objects must also be polished afterwards. Finally, even more uneconomical would be a chemical copper plating due to the necessary high working temperature, the high costs of the necessary, high-purity chemicals, their disposal problem, their critical hand- tion and process control, the very slow rate of deposition and the low ductility and gloss level of the copper layers

A thick copper plating or thick nickel plating can only be carried out electrolytically in an acidic bath economically. As a much more uneconomical alternative could serve a chemical Dickvernickelung, however, requires a much slower deposition rate, very long treatment times and very high costs for their complicated wastewater treatment and for the necessary high-purity chemicals.

In the case of workpieces coated with an electrolytically produced barrier layer, this results in better corrosion protection, better electrical conductivity and / or esthetically and visually better layers than the base material itself has. Further advantages of acidic electrolytic copper baths are high-gloss ductile, fine-pored coatings, which have good hiding power and metal distribution, as well as the high deposition rate and high efficiency. They are therefore clearly preferable to the alkaline, cyanide-free, complexing agent-containing copper plating baths and / or the cyanide copper plating baths and / or nickel strike baths with existing barrier layer on materials with lower noble potential.

A disadvantage of such Glanzverkupferungen is still that base metals and alloys with electronegativerem potential as copper such as iron, steel, zinc, tin or zinc die casting can not be coated directly in these baths, because they must be previously provided with a barrier layer ,

A disadvantage of all four variants described above, that for applying the necessary barrier layer according to one of the variants 1) to 3.) and then in the glossy or thick copper 4.) for metal deposition Electricity is required: Depending on the process, application and base material, between 0.5 and 5 A / dm ² current density is used, exceptionally up to 50 A / dm ² . For a gloss or thick nickel bath, the current density is usually about 2 to 5 A / dm ² . For an often additionally used Vercadmung, chrome plating, silver plating, gold plating, rhodium plating or / and platination, the current density is about, depending on the method, in the range of 1 to 10 A / dm ^second In addition, treatment times between 5 and 30 minutes are needed. Therefore, these barrier layers are as described under variants 1.) To 3), after a comparatively complex, energy-consuming and slow and often produced by a very environmentally friendly process.

A process still common today in the galvanic treatment, in particular of steel, zinc or / and zinc die-cast parts, is the following: a) hot degreasing in aqueous solution of 10 g / l NaOH, 30 g / l sodium pyrophosphate and 5 g / L Wetting agent at 60 - 95 ° C for 5 - 10 minutes, b) cascade rinsing in demineralised water,

c) pickling depending on the application and base material - iron parts: 15% HCl and 1 g / l wetting agent, without pickling inhibitor

Room temperature over 5 - 15 minutes,

Zinc parts: 3% HF and 1 g / l wetting agent, without pickling inhibitor, at room temperature over 5 - 60 seconds,

d) cascade rinsing in demineralised water,

e) Electrolytic degreasing with cathodic switching of the article:

10 g / L KOH, 30 g / L sodium silicate, 10 g / L pyrophosphate and 1 g / L wetting agent at 0.5-2 A / dm ² , 1-5 V and 15-60 ° C above 0.5 - 5 minutes, f) cascade rinsing in demineralised water,

g) cyanidic copper plating in aqueous solution at 0.3-1.5 A / dm ² , 1-3 V, 60 ° C., efficiency of the current η 70% and max. 0.3 pm / min over 5 - 15 minutes with:

50 g / L CuCN, 50 g / L NaCN, 40 g / L NaOH, 1 g / L wetting agent, 3 g / L brightener or

Alkaline copper plating in aqueous solution at 0, 1 - 1, 0 A / dm ² , 15 - 20 V, 60 ° C, efficiency of the current η 90% and max. 0.25 pm / min for 5 - 15 minutes with:

15 g / L Cu, 50 g / L pyrophosphate, 1 g / L wetting agent, 3 g / L brightener and if necessary diluted KOH or diluted H ₃ P0 ₄ for pH adjustment to pH values in the range of 8.5 to 9.5,

h) cascade rinsing in deionised water.

With this treatment, all kinds of workpieces and also all base materials based on iron, zinc materials and / or tin can be copper-plated.

As a rule, these impact-brazed workpieces are then acid-coated or sour-coated thick. A bright copper plating usually has a layer thickness in the range of 5 to 50 pm. It can be applied electrolytically, but in industrial practice without electricity of suitable quality. A thick copper plating may have a layer thickness in the range of more than 50 μm to about 5 mm, but may possibly lead to several weeks of electrolytic or electroless copper deposition. Workpieces with a complicated geometry of the part to be treated are rarely treated again in an electroless immersion bath, such as in DE 20 26 698 A1, to subsequently apply a glossy or thick layer after an electrolytic cyanide copper plating. However, even in the plating baths described there, a strong complexing agent such as, for example, cyanide, gluconate or ethylenediaminetetraacetate (EDTA) with corresponding environmental, toxicity, wastewater treatment and treatment problems is always necessary. Examples of such complexing agents are amines and carboxylic acids such as, for example, gluconic acid, lactic acid, tartaric acid and derivatives thereof, such as, for example, sodium umgluconate, Rochelle salts, ethylenediamine, diethylenetriamine, diethanol-glyoxime, ethylenediaminetetraacetic acid, lactonitrile, ethylenedinitrilotetra-acetic acid (EDTA), hydroxyethylethylenediaminetriacetic acid (HEDTA), diethylenetrinitrilopenta-acetic acid (DTPA), nitrilotriacetic acid (NTA), triethanolamine, Tetrakis (2-hydroxypropyl) ethylenediamine (THPED), pentahydroxypropyldiethylenetriamine and their derivatives. Their wastewater treatment is very problematic. An alternative to an electrolytic plating bath could be an electroless plating bath or even an electroless plating bath. Preferably, a copper plating solution, in particular for the formation of a barrier layer should be free of strong complexing agents or free of complexing agents, free of toxic ingredients, without external electrical energy for metal deposition and bath heating, and without questionable wastewater treatment.

DE 20 26 698 A1 teaches a production process

a) 1. Copper layer electrolytic with cyanide,

b) rinsing,

c) 2. copper layer produced in an electroless alkaline immersion bath, with cyanide or with another strong complexing agent,

d) rinse and

e) Continue to galvanize.

In contrast, in the present invention, by contrast, the process steps a), b) and c) are replaced by an electroless cyanide-free copper plating.

Since the precipitates obtained in the electroless immersion bath described in DE 20 26 698 A1 are still relatively porous, since the previously known electrolytes in the alkaline pH range are very sensitive to inadequate parts cleaning and also to bad contaminants and are still added for adhesion purposes a galvanic, alkaline, cyanide or other alkaline pre-bath as an Impact bath is necessary and only in parts with difficult part geometries an improvement compared to a treatment in a cyanidic, electrolytic copper bath is detected without dip intermediate treatment, found the dip baths described there no greater use. Therefore, in textbooks and very little or nothing is described about electroless dip baths.

An electroless metal deposition takes place, if no further reducing agent was added to the solution, by cementation or by precipitation. The deposition principle is based on the series of metals, whereby the electrons of the nobler metal required for the reduction and the concomitant deposition are supplied by the more noble metal through an oxidation process.

As can be seen from N. Kanani: Copper layers: deposition, properties, applications, Eugen-G.-Leuze-Verlag Bad Saulgau 2000, p. 73/74, it is not possible to date, workpieces made of the basic materials iron, zinc or / and their alloys directly with a copper coating of acidic glossy and / or thick-film copper bath to provide. Therefore, today it is still necessary to workpieces, e.g. from the base materials iron, zinc or / and their alloys with a barrier layer, so that contact between the bath solution and the workpiece can be avoided. Depending on the base material, either 1) a cyanide alkaline electrolytic copper plating bath, 2.) an alkaline complexing agent-containing electrolytic copper plating bath, or 3.) an acidic electrolytic nickel strike bath are usually used.

Without a barrier layer, an acidic bath, such as an acidic copper plating or nickel plating bath, will exert a troublesome pickling attack on the clean or cleaned metallic surface based on iron and / or zinc, anytime a submerged metal is immersed in it The solution of a nobler metal, a Sudabscheidung takes place, because then iron or / and zinc ions in particular are herausgeizizt from the object to be coated, go into solution and electrons are released, which then in turn by the ions of the acidic see galvanic bath recorded be and require a Sudabscheidung.

The aim of every galvanic (= with current) treatment is to electrolytically deposit a cover layer on the metallic object from an acidic aqueous solution, since the acid electrolyte has significant advantages in terms of deposition rate, gloss, metal distribution, compared to an alkaline electrolyte. Opacity, porosity and efficiency offers. In addition, acidic electrolytes are less sensitive and more stable to contamination than cyanide-free alkaline electrolytes. Because alkaline electrolytes often cause several disadvantages. Therefore, cyanide-free alkaline electroplating processes are used only in rare cases, e.g. when the number of baths is e.g. for space reasons, not sufficient for removal to an acidic galvanic treatment. These baths then operate at pH's greater than 10, with a number of disadvantages, such as, e.g. Degree of gloss, sensitivity to impurities and foreign matter, slower deposition and, depending on the current density, poorer metal distribution and correspondingly poorer depth dispersion. Such an acidic aqueous solution, however, requires a barrier layer on metallic surfaces, especially of iron and zinc materials, so as not to pick up impurities, ions and electrons from the metallic substrate which interfere with the acidic aqueous solution, and the electrodeposition process and the quality of the electrodepositing layer affect.

DE 39 14 180 C2 discloses compositions of electroless copper sulfate based on copper sulfate and cyanide, which at operate at a pH of at least 9.5 and get the electrons necessary for metal deposition from a reducing agent, usually formaldehyde. In addition, this bath contains strong complexing agents such as EDTA and / or cyanide. DE 15 21 200 A1 describes alkaline electroless nickel baths which operate at a pH of at least 8.5 and which receive the electrons necessary for metal deposition from the reducing agent sodium hypophosphite. In addition, these baths contain stabilizing agents such as sodium citrate and / or ammonium chloride. No. 3,715,793 discloses electroless nickel and cyanide-free nickel thick films prepared from solutions having a pH of 3.5 or 7.5 to 9 at about 55 to 95 ° C or at a pH of 7.5 to 10 be deposited at 40 to 95 ° C.

A disadvantage of these electroless methods is that all metallic objects and also the foreign substances in the bath, constantly, as long as they are in the bath, are coated. Purely chemical, ie electroless copper and nickel baths, which enable the metal deposition with the aid of a strong reducing agent, have due to the necessary working temperature, the very high cost of the required, high-purity chemicals, their wastewater and disposal problems, their critical handling and litigation, the low ductility and gloss level and the very slow deposition rate in practice not enforced stronger.

So far, a workpiece made of iron materials including steels and stainless steels can only be adhered to copper and acid-free with layers suitable for further processing if at least one strong reducing agent such as hypophosphite or / and pyrophosphite is added to the bath and / or if a barrier layer is used in advance an eyanidi alkaline electrolytic copper bath, was deposited from an eyanid-free, alkaline complexing agent-containing electrolytic copper bath or from an acidic nickel-strike bath.

Heretofore, a workpiece made of zinc materials can not be acid-adhered and can be acid-plated with current-usable layers without current, or be acid-plated or alkaline-plated without current, without the bath having at least one strong reducing agent, such as e.g. Hypophosphite and / or pyrophosphite is added and / or without previously a copper barrier layer of a cyanide alkaline electrolytic bath or an eyanid-free, alkaline, complexing agent-containing electrolytic bath was deposited.

Until now, a workpiece made of iron or zinc materials can not be adhered to an alkaline state and can be alkaline-plated with current-usable layers without current or nickel-plated without current, without the bath having at least one strong reducing agent, such as e.g. Hypophosphite and / or pyrophosphite is added.

EP 1 495 157 B1 teaches an aqueous, freeze-thawing and thawing concentrate for coppering based on basic copper carbonate and complexing agent (s). It was the task of proposing a method in which a barrier layer and / or conductive layer can be applied by coppering in a simple, cost-effective, environmentally friendly and faster manner, in particular on iron and zinc materials.

The object was to propose methods for coating in which cover layers, such as, for example, gloss and / or thick layers, are applied electrolytically, without a cyanide alkaline bath, such as, for example, a copper coating, before the formation of the electrolytic cover layer (s). mung, copper plating, nickel plating or galvanizing bath or an electroless bath for the formation of a barrier layer is used.

Another object was to propose coating processes that are as cost-effective, fast, of high quality and environmentally friendly as possible. In doing so, it would be preferable to propose methods which are widely and easily applicable.

It has now surprisingly been found that electroless copper plating is also possible without difficulty on iron, zinc or / and tin workpieces including workpieces made of steels and stainless steels, with a simple process and with high quality of the barrier layer to be formed. This process is even surprisingly simple, inexpensive, reliable, fast, environmentally friendly and non-toxic. It can even be used free of added reducing agents.

The object is achieved with a method for treating a metallic surface of an article with an aqueous coppering solution in which on clean metallic surfaces of the article or after pretreatment on cleaned metallic surfaces a first copper plating solution which is free of cyanide and the is free of intentionally added strong reducing agent having a potential with values of less than -0.6 V, or which is free from intentionally added reducing agent, used to form a first copper layer or copper alloy layer as a barrier layer and / or as a conductive layer without current becomes. In such processes, however, can not be excluded that z. B. by entraining reductant from another process step and / or area within the plant and / or from the air is entered and / or that a registered foreign substance in the process according to the invention reacts to a reducing agent. Particularly preferably, the first copper plating solution is cyanide-free and free of strong reducing agent, which has a potential with values less than -0.6 V, or even free of reducing agent.

In particular, metallic surfaces of iron, zinc, tin or / and their alloys can be copper-plated with the method according to the invention. Preferably, an article is treated from a ferrous material, zinc and / or a zinc alloy.

Preferably, a first copper plating solution is used cyanide-free electrolessly for the formation of a barrier layer and / or a conductive layer on a less noble metallic surface than copper. With the copper plating solution according to the invention, that is to say with the copper plating bath according to the invention, it is possible with appropriate chemical composition of the bath, that is to say with content of at least one alloying element, such as, for example, Zinc and / or tin, also a copper alloy layer are formed. For the sake of simplicity, however, only copper layer and copper plating will be referred to below, even if a layer of a copper alloy is formed. In this sense, indications such as "nickel" in the baths are intended to include both nickel and nickel with alloying elements and nickel and nickel alloy layers, respectively.

In a particularly preferred embodiment, an article of ferrous material, zinc, zinc alloy or / and a tin material is treated with the proviso that the first copper plating solution in the treatment of an article of iron or steel, optionally with the exception of stainless steel, no Contains complexing agent. For the coppering of stainless steel, a weak complexing agent is particularly advantageous.

The object is also achieved with an article having a barrier layer and / or a conductive layer, which is produced according to the invention. The barrier layer and / or conductive layer is preferably completely free of pores. If appropriate, at least one galvanic cover layer, for example based on copper, nickel or one of its alloys, is also applied electrolytically to the electrolessly applied barrier layer and / or conductive layer. In particular, it is the use of a method for treating a metallic surface of an article with an aqueous copper plating solution according to the invention and / or articles coated according to the invention for electroless formation of a first copper layer or copper alloy layer as a barrier layer and / or as a conductive layer, especially on surfaces of iron. Materials, zinc materials or / and tin.

The copper plating solution used according to the invention can therefore be free of strong complexing agents, such as e.g. Complexing agents and / or complexes based on cyanide, diethylenetriamine, diethanolglyoxime, ethylenediamine, ethylenediaminetetraacetic acid, hydroxyethylethylenediaminetriacetic acid (HEDTA), diethylenetrinitrilopenta-acetic acid (DTPA), gluconic acid, lactonitrile, nitrilotriacetic acid (NTA), Rochelle salts , Triethanolamin, tetrakis (2-hydroxypropyl) ethylenediamine (THPED), Pentahydroxypropyldiethylen- triamine and derivatives thereof, in particular free of ethylenediaminetetraacetate (EDTA) with appropriate environmental, Toxizitäts-, Abwasserbehandlungsoder / and treatment problems, held.

The copper plating solution used in accordance with the invention is preferably also kept free of weak complexing agents such as complexing agents and / or complexes based on lactic acid, acetic acid, tartaric acid, citric acid and derivatives thereof and mixtures thereof. In contrast, an environmentally friendly weak complexing agent such as based on citric acid, lactic acid, acetic acid, tartaric acid and / or derivatives thereof does not interfere with copper plating solutions of the invention nor with the disposal of copper plating solution residues. An addition of citric acid or / and one of its derivatives, such as a citrate, for example sodium citrate, potassium nitrate and / or ammonium citrate, can be of advantage, in particular in the case of metallic surfaces which are difficult to be coppered, for example those made of stainless steel, in particular in the bath in the range from 0.1 to 120 g / L, from 1 to 80 g / L, from 3 to 60 g / L, from 6 to 35 g / L or from 12 to 20 g / L.

However, the copper plating solution used according to the invention can also be kept free from strong reducing agents, since these are also environmentally unfriendly and hazardous to sewage and sometimes also toxic. Because complexing agents and strong reducing agents require additional treatment in wastewater. Preferably, the first coppering solution contains no intentionally added complexing agent, more preferably no complexing agent.

Since Sn ²⁺ ions have a potential of -0, 14 V, since Fe ²⁺ ions have a potential of -0.44 V, and since Zn ²⁺ ions have a potential of -0.76 V based on measurements with a standard hydrogen electrode Although, inter alia, these ions also have a reducing effect, these ions are not considered as reducing agents in the sense of this definition. To distinguish weaker reducing agents with a small potential, which is on the order of +0.2 V or 0 V, ie comparatively large values of the voltage, the strong reducing agents according to this definition should have a potential of -0.6 V. or even lower negative values of the voltage, such as values in the range of -0.8 to -1.8 V. Therefore, either no reducing agents or no strong reducing agents are added to the copper plating solution according to the invention. But the herausgebeizten from the metallic surface and / or dissolved ions such as Fe ²⁺ , Sn ²⁺ , Zn ²⁺ or / and other ions such as alloying constituents and / or other metallic materials of the treated metallic surface, often values in the range from -0, 1 to -3 V also act as a reducing agent. Therefore, the inventive method requires a content of such ions, which are inevitably obtained by pickling and / or leaching out of the metallic surface and act reducing. Therefore, the copper plating solution of the present invention does not require a strong reducing agent, and particularly no reducing agent, which is intentionally added to the copper plating solution. Preferably, the first copper plating solution contains no added reducing agent and no strong complexing agent except for the ions dissolved out and / or leached out of the surfaces.

The herausgebeizten from the metallic surface and / or dissolved out ions such. As Fe ²⁺ , Sn ²⁺ , Zn ²⁺ or / and other ions serve as native reducing agent. Because the surface z. B. the iron material is angeizizt, so that the herausgeizizizten or / and dissolved out, for example, iron ions can act as a reducing agent. Therefore, the electroless coppering used according to the invention works at least immediately after the first contact with a base metal or material with ions such as Fe ²⁺ in its solution. For iron-containing surfaces, it is preferred to operate at a pH of less than 5, preferably less than 3, more preferably less than 2 or less than 1, to allow pickling on the metallic surface. In the case of surfaces of zinc and / or other base metals, preference is given to working in the weakly acidic, in the neutral or in the alkaline range. Then no zinc goes through pickling from the zinc surface in solution. The pH for zinc-rich surfaces is preferably at least 4, otherwise zinc would be seeded and otherwise it could easily lead to the destruction of the base material. Because the pickling attack on zinc is many times stronger than iron. At pH values in the range of 4 to 8, and especially 6.5 to 8, zinc-rich surfaces can be well worked with zinc being due to the potential difference between Zinc and copper go into solution and not because of the pickling attack. The thus dissolved zinc ions and / or ions of other base metals that have been leached out and / or dissolved out, apparently act as native reducing agents. Therefore, no reducing agent must be added. The minimum potential of the native reducing agent is -0.44 V for iron and -0.76 V for zinc when measured with a standard hydrogen electrode. Preferably, the first copper plating solution contains ions having values of potential in the range of -0.1 to -2.5 V or -0.4 to -2 V. In the method according to the invention, the barrier layer and / or conductive layer produced according to the invention can also be applied to iron and zinc materials including stainless steel and to tin in a simple, inexpensive, environmentally friendly and faster manner than by prior art methods. Preferably, this method does not involve expensive additional process steps such as, for example, a necessary electropolishing or a necessary electrolytic degreasing.

When steps before the coppering according to the invention may be necessary if necessary:

1 . An alkaline or pH neutral hot degreasing, e.g. Remove residues of grease, oil, dust, etc., and then rinse with water.

2. Activation of the particular oxidically contaminated metallic surface, for example by acidic or rarely even alkaline pickling and / or by mechanical processing such as lapping, grinding, blasting and by subsequent rinsing with water. In the case of alkaline pickling or omitting any kind of such activation step, pickling with a highly diluted, slightly acidic aqueous liquid is common. With the barrier layer according to the invention a pickling attack of the subsequent acidic electrodeposition bath is avoided on the base material, since the copper barrier layer is not or not materially attacked by the subsequent galvanic bath. The copper barrier layer or / and Kupferkonduktivschicht invention consists either only of copper or substantially copper, and optionally of a low content of alloying constituents for copper, optionally from a low content of brighteners, other additives and / or minor other addition of the copper plating in the Layer of built-in components.

The copper plating solutions used according to the invention for electroless formation of a barrier layer and / or conductive layer are aqueous compositions which can vary widely with regard to their concentrations and their additives. They contain at least one copper compound such as a copper sulphate hydrate. The copper content of the copper plating solution as a bath solution may be in the range of 0.5 to 120 g / L Cu, preferably in the range of 1 to 100 or 2 to 80 or 5 to 60 or 7 to 40 or 9 to 25 or from 1 to 18 g / L Cu. In contrast, the other additives to the coppering solution used in the invention can vary a lot, so that no kind of addition moreover necessarily must be included in each bath. If desired, it may in each case comprise at least one / one / one mordant, pickling inhibitor, pickling agent, chelate, chelating agent, brightener, complex, weak or complexing agent, wetting agent, buffer substance, a weak reducing agent, acid, adjusting agent for the pH and / or optionally have further additives. It preferably contains ions and in particular leached or / and leached ions such as Fe ²⁺ , Zn ²⁺ or / and other ions which have been leached out of alloying constituents and / or from other metallic materials of the treated metallic surface and / or dissolved out and the values of Potentials in the range of -0.4 to -1, 8V. The total content of the coppering solution as a bath solution of solids and active ingredients is often in the range from 1 to 400 g / L and preferably in the range from 2 to 300 or from 5 to 250 or from 10 to 200 or from 20 to 150 or from 30 to 125 or from 40 to 100 or from 60 to 80 g / L. The largest contents usually have the at least one copper compound and optionally also at least one acid or / and at least one weak complexing agent.

It has now been found that the leached or / and leached ions, in particular of Fe ²⁺ , Sn ²⁺ and Zn ^{2+ have} the same effect as added strong reducing agents. Because it has been found that the herausgeizizizten or / and dissolved ions are necessary for the inventive method, if no strong reducing agent is added. Even at the beginning of the work, it is usually not necessary to add such ions to the bath, because the copper plating begins on metallic surfaces even without the addition of eg Fe ²⁺ , Sn ²⁺ and Zn ²⁺ , so that when immersing the object to be treated base metallic material in the usually acidic or neutral copper plating solution are automatically liberated ions, which then act as a reducing agent. In particular, ions of relatively non-noble metals such as Fe ²⁺ or / and Zn ²⁺ can serve as native reducing agents.

The copper plating solution according to the invention can contain acids such as, for example, sulfuric acid, hydrochloric acid, nitric acid and / or hydrofluoric acid, in particular in amounts ranging from 0.1 to 200 g / L, more preferably from 5 to 130 g / L or from 50 up to 80 g / L. Preferably, the total acid content is in the range of 0.1 to 400 g / L or 10 to 200 g / L or 30 to 130 g / L. The copper plating solution according to the invention may be added as a pickling inhibitor, for example an amine such as tributylamine, butynediol, cyclohexanol, nitrobenzenesulfonic acid, propynol, putindiol or / and one of its derivatives. As a pickling booster, it is often preferred to use at least one alkali metal halide such as sodium chloride and / or sodium fluoride in acidic solutions.

Complexing agents such as e.g. Citric acid and its derivatives as well as chemically related carboxylic acids and their derivatives are regarded as weak complexing agents in electroplating. Many compositions for electroless copper plating do not require the addition of complexing agents. It is often beneficial to add no complexing agent, because this is beneficial for wastewater treatment, because even weak complexing agents can solve salts such as nickel and cause environmental damage. The stronger a complexing agent contained in the bath, the greater the required outlay for wastewater treatment. The copper plating solution according to the invention is preferably free of strong complexing agents, e.g. free of cyanides, amines, carboxylic acids and their derivatives, as these cause a corresponding environmental, toxicity, Abwasserbehandlungs- o- / / and treatment problems. They are preferably not intentionally added in many embodiments. Examples of such complexing agents are e.g. Gluconic acid, lactic acid, tartaric acid and their derivatives, e.g. Sodium gluconate, Rochelle salts, ethylenediamine, diethylenetriamine, diethanolglyoxime, ethylenediaminetetraacetic acid, lactonitrile, ethylendinitrilotetra-acetic acid (EDTA), hydroxyethylethylenediaminetri-acetic acid (HEDTA), diethylenetrinitrilopenta-acetic acid (DTPA), nitrilotri-acetic acid (NTA ), Triethanolamine, tetrakis (2-hydroxypropyl) ethylenediamine (THPED), pentahydroxypropyldiethylenetriamine and their derivatives.

But a subsequent electrolytic topcoat need not be made with an electrolyte that is free of strong chelating agents - regardless of their composition and a content of, for example, Ag, Cu, Ni or / and Cr.

For example, ethylenedinitrilotetraacetic acid (EDTA), triazole, ascorbic acid, porphine, heme, chlorophyll or / and derivatives thereof, and in particular ethylenedinitrilotetraacetic acid dinitrate, dialkylaminoethyltolyltriazole or / and sodium ascorbate can be used in the copper plating solution according to the invention as chelating agents or as corresponding chelates. The total content of chelating agents or / and of corresponding chelates in the coppering solution according to the invention is preferably in the range from 0.001 to 100 g / L, more preferably in the range from 0.1 to 20 g / L or from 0.5 to 5 g / L.

As a brightener, the copper plating solution according to the invention may comprise, for example, at least one compound based on alkylsulfonic acids, on amines, e.g. Reaction products with propylamines, of benzenesulfonic acids, of coumarins, of esters of (meth) acrylic acids, of melilotric acid, of saccharines, of sulfonamines, of sulfonimides or / and of sulfinic acids.

As wetting agent, for example, multiple alcohols, ether compounds, ethoxylates, carboxylates, sulfonates, sulfates, quaternary ammonium compounds, ethane compounds, surfactants or / and derivatives thereof can be used in the copper plating solution according to the invention. The total content of wetting agents in the coppering solution according to the invention is preferably in the range from 0.001 to 100 g / L, more preferably in the range from 0.1 to 20 g / L or from 0.5 to 5 g / L. Boric acid, ammonia, carbonic acid, acetic acid, sodium carbonate, amines, aminomethane, sulfonic acids, citric acid, acetates, borates, ammonium compounds and / or derivatives thereof can be used as buffer substances in the copper plating solution according to the invention. the. The total content of buffer substances in the copper plating solution according to the invention is preferably in the range from 0.001 to 100 g / L, more preferably in the range from 0.1 to 20 g / L or from 0.5 to 5 g / L.

As setting agents, for example, acids and bases or / and their derivatives can be used in the copper plating solution according to the invention. The total content of setting agents in the coppering solution according to the invention is preferably in the range from 0.001 to 100 g / L, more preferably in the range from 0.1 to 20 g / L or from 0.5 to 5 g / L.

For the electroless formation of the barrier layer and / or conductive layer, the copper plating solution according to the invention preferably contains at least one copper compound and at least one brightener, at least one acid or / and at least one mordant. With particular preference, it additionally contains at least one pickling inhibitor and optionally also a pickling agent. Alternatively or additionally, it may particularly preferably also contain at least one brightener.

The copper plating solution according to the invention is free of deliberately added strong reducing agent, ie free of reducing agent, which has potential values of at most -0.6 V and in particular values in the range of -3 to -1 V. It is preferred to keep the copper plating solution according to the invention free or as free as possible of stabilizing agents for the copper plating solution on an organic and / or inorganic basis. For example, diethylenetriaminepentaacetic acid, phosphonic acid, thioglycolic acid, thiourea or / and derivatives thereof can be used as organic stabilizers. As inorganic stabilizers, for example, compounds based on cadmium, lead, vanadium or / and mercury can be used. Usually, such stabilizers are poorly biodegradable. Because the organic stabilizers can dissolve metals from sediments and, where appropriate, cause their transport into waters, whereas the inorganic stabilizers are toxic and environmentally unfriendly. In general, it is preferred to keep the copper plating solution according to the invention free or as free of toxic heavy metal ions as possible.

The pH of the copper plating solution according to the invention is preferably adapted to the materials of the metallic surfaces which are to be copper-plated. At a low pH value of the copper plating solution according to the invention, a pickling attack occurs on a ferrous material such as on a steel sheet. As a result, Fe ^{2+ is leached} out and goes into solution. As a result, electrons are released, which are absorbed by the copper. As a result, metallic copper is deposited. For the copper plating of metals that are less noble than, for example, iron, and for their alloys, the pH of the copper plating solution is often preferably in a range of about 4 to 8 or 5 to 8. For the copper plating of zinc or zinc-containing Alloys, the pH of the copper plating solution is more preferably in a range of 4.5 to 7 or from 6 to 7.5. The pH value of the copper-plating solution is particularly preferably in the range from 0 to 2 in the case of iron-rich workpieces, more preferably in the range from 4.5 to 7.5 or from 6.5 to 7 in the case of zinc-rich workpieces. Particular preference is given to pH Value of the first copper plating solution for zinc-rich or tin-rich metallic surfaces in the range of 4.5 to 8.5 or from 6 to 8 or for iron-rich metallic surfaces at less than 5. The electroless copper plating according to the invention or / and a subsequent electrolytic Coating can be done by dipping, spraying, rolling, brushing, casting, by sponge application, by pad application or / and in a similar manner. Usually work is done in diving. Preferably by dipping, spraying, rolling, brushing, Casting, by sponge job and / or by padding order without power and / or electrolytically coated afterwards. Preferably, the article provided with a barrier layer and / or conductive layer undergoes at least one subsequent surface treatment. For successful electroless copper plating, it is important to ensure that the metallic surfaces for electroless copper plating are metallically bright and free of grease. It must also be ensured that the copper concentration in the copper plating solution, the bath temperature, the treatment time, the content of pickle inhibitor or / and the content of brightener in the copper plating solution are coordinated.

The temperature at which electroless copper plating according to the invention is preferably in the range from 15 to 95.degree. C., particularly preferably in the range from 20 to 85.degree. C. or from 30 to 70.degree. C., is preferred. If coppering takes place at temperatures above 50 ° C, the treatment time is considerably shorter. But when working at higher temperatures, care should be taken that the concentration and / or treatment time are not too high to avoid spongy, poorly adherent layers. On the other hand, it is also possible to copper at temperatures below 50 ° C., paying attention to sufficiently high concentrations and / or sufficiently long treatment times, to porous copper layers and thus to the lack of blocking effect of the barrier layer or the insufficient conductivity of the conductive layer and the contamination of the bath and to avoid problems in subsequent process steps. Working at room temperature is also possible, if sufficient concentration of the copper solution and / or sufficient treatment time is taken into account.

Preferably, over a time in the range of 0.05 to 30 minutes, from 0.2 to 10 minutes or preferably over 0.5 to 2 minutes electroless copper plating to a copper layer according to the invention as a barrier layer and / or as Conductive layer form. If the bath has a lower concentration than, for example, 0.5 g / L copper in the copper plating solution, then a higher bath temperature and / or longer treatment time should be taken into account. If the copper plating bath has a higher concentration than, for example, 100 g / L Cu in the copper plating solution, attention must be paid to lower bath temperature, shorter treatment time, higher levels of pickle inhibitor and / or higher levels of brightener. However, if the copper concentration in the bath, bath temperature, treatment time, pickling inhibitor content and / or brightener content in the copper plating solution are not matched, then either porous copper layers or spongy, poorly adherent copper layers may be formed. In the case of electroless copper plating according to the invention, a copper layer thickness in the range of, for example, from 0.1 to 8 μm or in the range from 1 to 5 μm, in particular within 0.5 to 2 minutes, preferably forms. By electroless copper plating a much faster coppering is possible than with electricity or by an electroless copper plating with the aid of a reducing agent. It is also significantly more energy efficient. The time saved in electroless plating is around 20 to 90% compared to electrolytic or electroless plating. The energy savings in the electroless deposition is about 90 to 100% compared to the electrolytic deposition. It amounts to about 40 to 70% in electroless plating compared to the electroless, chemical deposition, because the chemical copper deposition is very slow, and it is always above 60 ° C and sometimes working at more than 90 ° C. Because at high copper contents, the copper plating solution becomes unstable and, in addition, spongy, poorly adhering copper layers can then form. Advantageously, there is also a better corrosion protection o- / / and a better electrical conductivity than the base material itself has.

The at least one electrolessly produced copper layer according to the invention can, if required, be further electrolytically copper-plated or / and further electrolytically nickel-plated, e.g. to apply in each case at least one bright copper layer, thick copper layer, bright nickel layer or thick nickel layer. Preferably, after the formation of the barrier layer and / or conductive layer, at least one cover layer is applied chemically or electrolytically as a galvanic luster layer or at least one layer as a thick layer. These coatings can be of good quality, but are particularly expensive to produce. Chemical thick films are particularly advantageous in difficult-to-workpieces, since they have the same layer thicknesses regardless of the workpiece geometry. Because the current is unevenly distributed in holes, cavities, edges, etc. having workpieces and leads to different layer thicknesses proportional to the current. On top of this, if necessary, in each case at least one electrolytic silver, chromium, gold, cadmium, platinum or / and rhodium layer can be additionally applied, in particular from acidic, cyanide-free and reducing agent-free electrolytes, e.g. as at least one gloss and / or at least one thick layer.

The object provided with an electrolessly produced copper layer can be electroplated at least once after application of the barrier layer and / or the conductive layer, can be coated at least once, can be coated at least once with at least one powder coating, with at least one cathodic dipcoat (KTL) or / and can be combined with at least one other item. Joining can be achieved, for example, by gluing, clinching or / and joining rolling under pressure and optionally also at high temperature. Preferably, the object provided with an electrolessly produced copper layer is treated galvanically at least once, painted at least once or coated with a powder coating or with a cathodic dip coating (KTL) or joined together with another object.

It has been found that with the method according to the invention surfaces of iron, steel, zinc and zinc alloys can be well coppered. For example, zinc die-casting alloys such as. B. ZnAIMg and ZnAIMgCu alloys (ZAMAK alloys) well electroless copper according to the invention.

Copper plating could not be achieved with very inhomogeneous or superficially heavily soiled zinc alloys, e.g. When aluminum halos in the alloy undergo deposition due to the potential difference between, e.g. AI and Zn have prevented. If electrolytically galvanized in these situations, rinsed with water and then copper-plated according to the invention electroless, this problem could be solved.

The electroless copper plating according to the invention of stainless steel surfaces is more difficult than with steel surfaces, in particular because of the natural oxide skin on the stainless steel surfaces. Stainless steel surfaces, for the pickling, at least one non-oxidizing acid for previous activation, and for the electroless copper plating optionally also an electrically conductive contact of a less noble metal than stainless steel such as aluminum, aluminum alloy, low-alloyed iron and steel materials, Zinc and / or zinc alloy was used to stainless steel surface, for example via a contact wire, could be successfully copper in several attempts. In the method according to the invention stainless steel surfaces are electrolessly copper-plated by pickling before the copper plating at least one non-oxidizing acid is used for the previous activation and by additionally using an electrically conductive contact of a less noble metal as stainless steel to the stainless steel surface for coppering, if necessary. Because stainless steel often behaves differently than the other iron and steel materials and often can not be easily stained in sulfuric acid. An electrically conductive contact with a less precious metal than stainless steel appears to be necessary in the case of stainless steel surfaces, which contain a higher content of steel refiners such as Cr, Ni or / and V, for example. For at low levels of steel refiners, the degreased and pickled stainless steel surfaces could be well copper even without using an electrically conductive contact with a less noble metal than stainless steel. Such electrically conductive contact of a sacrificial metal eg of aluminum, aluminum alloy, low alloyed ferrous and steel materials, zinc and / or zinc alloy to a stainless steel surface allows the sacrificial metal in the copper plating solution to provide electrons for metal deposition. This is a pickling attack on the sacrificial metal, which goes into solution. The released electrons migrate via the electrically conductive contact to the stainless steel surfaces. Due to a sufficient number of free electrons, the stainless steel surfaces can then be copper-plated. For higher-alloyed stainless steels, the so-called sedimentation in the dipping process only works when it is used in the contact and dipping process. In the case of stainless steels with a low content of steel finishers, the release of electrons appears to be hindered less than with higher-alloyed stainless steels. Therefore, it is possible for some stainless steel alloys to successfully copper even without electrically conductive contact of the stainless steel surface with a sacrificial metal stainless steel surface. In the case of low alloyed stainless steels, the so-called sedimentation in the dipping process already works when it is used in the immersion process. The copper plating quality does not suffer from this. The bath contents and the thermal conditions for coppering precious metals Steel surfaces are the contact and dipping method as well as the

Dipping process almost the same as when coppering steel surfaces.

Furthermore, it has now been found that also tin surfaces can be copper-plated according to the invention. The bath contents and the thermal conditions for copper-plating tin surfaces are almost the same as when coppering zinc surfaces.

It has now been found, surprisingly, that on with the products Gardobond ^® CU 7600 and Gardobond ^® CU 7602 Chemetall GmbH, Frankfurt am Main, easily high-quality copper barrier layers normally in particular of materials as iron, steel, zinc, tin and even Zinc diecasting can be applied in an environmentally friendly way. They enable a high-quality primer for decorative or / and functional further processing in galvanic coating technology. In some cases, as explained in more detail in the examples or comparative examples 6 to 9, this also allows extensive electrolytic processes to be replaced. The high adhesion of the obtained coatings was confirmed. Thus, it is possible to dispense in electroplating in the decorative and / or functional coating of workpieces such as iron, steel, zinc, zinc die-cast or tin on an electrolytic pre-copper plating or electrolytic nickel plating to form a barrier and by an electroless plating process in an acidic Bad to replace.

It has now surprisingly been found that it is possible to apply a barrier layer and / or conductive layer on metallic objects with a cyanide-free, for example electroless, copper plating solution. Here it was surprising that it is possible, then an acidic electroplating on surfaces of Iron- or / and zinc-rich metallic objects or to apply tin - because to date surface coaters learn that a layer deposited on an object with a surface based on iron and / or zinc from an acidic copper electrolyte, not suitable for further processing is.

Here it was surprising that it is possible to apply directly to the copper barrier layer according to the invention without subsequent copper or copper thick copper layer subsequent nickel gloss or nickel thick layer, without suffering a loss of quality. Surprisingly, however, it was also found that with the method described in the invention, for example, barrier layers for nitriding steel, even partially, or layers for increasing the electrical conductivity of a component, can also be produced selectively on only a part of the surface. In addition, it has surprisingly been found that it is also possible to deposit bright copper layers with the method according to the invention, so that even in some cases a subsequent acid gloss copper plating or subsequent acid luster nickel plating can be dispensed with and, if required and depending on the application, thereafter directly galvano-plated. nickel-plated, galvanically bright gold-plated, galvanically bright silver-plated or / and galvanically bright chrome-plated.

At least one electrolytic luster or electrolytic thick nickel layer can be applied directly to the barrier layer and / or conductive layer applied according to the invention without the objects provided with a barrier layer having to be previously additionally coated with an acidic, electrolytic, lustrous copper layer. This is independent of whether electroless with a cyanide-containing copper plating solution or with a copper plating solution used according to the invention was worked. It is also independent of whether the barrier layer was applied to a surface, for example made of an iron material, a zinc material, a tin material or / and on a nobler surface. The coated with a conductive layer according to the invention coated article can be used for the production of a more electrically conductive object such as a wire, profile, pipe, rod or intricately shaped object, for conductive heating and / or curing of the metallic article Der with a barrier layer according to the invention or / Conductively coated article can be used as a wire, profile, pipe or rod, as a welding wire, as a fitting, element or connecting element eg for windows, doors or furniture such as a roll or a screw, as an element of an apparatus, a machine, a Household appliance, an electronic article, an electronics article or toy such as a switch or button, as a jewelry item such as a candle holder, as an element for a clock, as a housing, linkage, bracket, mounting plate or paneling, as an element in apparatus construction, mechanical engineering, automotive or for Ve means of transport, as a mechanical functional part or for a metallic object to be hardened, such as a drill, an element subject to wear, in particular in apparatus construction, in vehicle construction, in mechanical engineering or in tool making or as a screw.

Examples and Comparative Examples:

The following examples and comparative examples are intended to illustrate the invention by way of example.

A hull cell sheet is a sheet that can be inserted into a Hull cell. The Hull cell has a cross-section in the form of a trapezoid. Due to the trapezoidal layout of the Hull Cell varies the distance between anode and cathode. As a result, the current density between the cathode and anode is varied, wherein the smallest distance between the two electrodes, the highest current density and the largest distance of the two electrodes corresponds to the smallest current density. However, the current density distribution is not linear, but increases faster as the distance becomes smaller. Therefore, it is possible to test an electrolyte such as an acidic high-gloss copper bath on a single Hull cell sheet over a wide current density range important for metal deposition. The adhesion of the applied layers was checked by means of crosshatch, wipe and bending tests in accordance with DIN EN ISO 2409, according to DIN EN ISO 1519 and according to ASTM 2794 and confirmed to be well adhering with these tests in all examples according to the invention.

Inventive Example 1 to electroless copper barrier layer: Two commercially available Hullzellenbleche steel ST2 were degreased in 10 g / L NaOH, 30 g / L sodium pyrophosphate and 5 g / L wetting agent at 70 ° C for 3 minutes alkaline hot, rinsed thoroughly with city water, 10 Decanted in 5% sulfuric acid (= briefly pickled to activate the surface) and rinsed again in city water. As a result, the metallic surfaces were excellently cleaned. Subsequently, the cleaned sheets were immersed in an electroless bath to form a barrier layer. The bath of the first coppering solution had the following aqueous composition:

100 g / L Gardobond ^® CU 7602 Chemetall GmbH and

150 g / LH ₂ SO ₄ technically pure and other additives.

Gardobond ^® CU 7602 is sold by Chemetall GmbH as a freeze-stable and thaw-stable concentrated aqueous solution. The solution diluted with city water from Gardobond ^® CU 7602 from Chemetall GmbH points an aqueous composition based on basic copper carbonate, weakly basic buffer substance, weak complexing agent and brightening agent. The copper plating solution according to the invention prepared with sulfuric acid was used at a temperature of 30 ° C. and at a pH of less than 0.5 over 0.5 minutes. This was followed by rinsing with city water at room temperature.

Due to the low pH of the electroless bath solution, a pickling attack took place on the steel sheet. As a result, Fe ^{2+ was leached} out and passed into the solution, releasing electrons. The electrons were in turn taken up by the copper ions present in the solution. Metallic copper struck the iron part. The special formulation and combination of raw materials of the product Gardobond ^® CU 7602 made it possible to achieve particularly adherent copper barrier layers by the chemical bonding of the layer with the base material. The coated with a copper barrier layer sheets already showed a high adhesion and clear gloss, even without a bright copper layer was applied. The layer thickness of the barrier layer was 1, 4 - 1, 5 pm and was evenly distributed on the front and back of the sheet. The copper barrier layers could not be scraped off with a fingernail. The crosshatch adhesion test was passed with GT0. A bending of the Hullzellenbleches over 180 ° was possible without Schich- tabplatzungen at Biegeinnen- and Biegeaußenkante. The applied barrier layer was extremely ductile, non-porous, fine crystalline and without internal layer stresses. Subsequently, the sheets were in a conventional acidic high-gloss copper bath at 2 A / dm ² and at a temperature of 35 ° C for 15 minutes or for thick films over 60 minutes electroplated or thickly coppered. Then they were rinsed with city water again and dried. On the electrolessly applied copper barrier layer would also directly followed by a bright nickel plating instead of Glanzverkupferung so that then both the cyanide copper plating, as well as the acid Glanzverkupferung the conventional manufacturing process could have been omitted. The sheets also showed smooth, high gloss and over the entire current density range of 0.1 to 20 A / dm ² in acidic under varied pretreatment conditions and under varied conditions for forming the barrier layer such as temperature, concentration and immersion time based on Gardobond ^® CU 7602 , glossy copper electroplated very well adhering copper barrier layers, the good adhesion was confirmed by tests in the crosshatch and bending test.

The bright copper and thick copper layers were high gloss. They showed excellent adhesion. All properties of all copper layers were high quality and impeccable. The inventive method was particularly fast, easy, inexpensive, without much energy and effortless.

Thereafter, if required, it would then be possible further to electrolytically copper-plating, electrolytically nickel-plating or otherwise electrolytically depositing or chemically coating colored electrolessly coatings. Furthermore, after each of these coatings, it would also have been possible to apply lacquer or adhesive instead of further coatings produced galvanically or without electricity.

Inventive example 2 to electrolessly and chemically varied produced copper barrier layer: Two Hullzellenbleche steel ST2 were pretreated and coppered as in Example 1, but an electroless dip bath was carried out in 100 g / L Gardoboncf CU 7600 of Chemetall GmbH and

150 g / LH ₂ S0 ₄ of technically pure quality.

Gardobond ^® CU 7600 is sold by Chemetall GmbH in powder form. The aqueous solution of Gardobond ^® CU 7600 contains copper sulfate hydrate, pickling inhibitor, pickling agent and wetting agent. The Hull cell plates were treated at a temperature of 30 ° C at a pH <1, in particular at pH values of about 0.5, for 0.5 minutes. Then it was flushed with city water.

Due to the low pH, a pickling attack took place on the steel sheets. As a result, Fe ^{2+ was leached} out and went into solution. As a result, electrons were released, which were absorbed by the copper. As a result, metallic copper fell on the sheet.

Subsequently, the sheets were in a conventional acidic high-gloss copper bath at a current density of 2 A / dm ² and at a temperature of 35 ° C for 15 minutes or for thick films over 60 minutes electroplated or thickly coppered. Then they were rinsed with city water again and dried. This electrolessly applied copper barrier layer could also have been followed directly by a bright nickel plating instead of the bright copper plating, so that then both the cyanide copper plating and the acid copper plating could have been omitted.

The sheets showed under varied pretreatment conditions and varied conditions for electroless formation of the barrier layer using Gardobond ^® CU 7600 as concentrations, temperatures and immersion times smooth, high gloss and very good adhesion over the entire current densities te-area copper barrier layers. The thickness of the applied barrier layer was 1, 6 - 1, 7 pm and was evenly distributed on the front and back of the sheet. The uniformity was confirmed by crosshatch and bending test. The copper barrier layers could not be scraped off with a fingernail. The crosshatch adhesion test was passed with GTO. A bending of the Hullzel- lenbleches over 180 ° was possible without Schichtabplatzungen at Biegeinnen- and Biegeaußenkante. The applied barrier layer was particularly ductile, nonporous, fine crystalline and without internal layer stresses.

Thereafter, if required, it would then be possible to continue to be electrolytically copper-plated, electrolytically nickel-plated or otherwise electrolytically deposited, and / or electrolessly chemically colored coatings to be deposited. Furthermore, after each of these coatings, it would also have been possible to apply lacquer or adhesive instead of further coatings produced galvanically or without electricity.

Comparative Example 3 for acid plating without barrier layer:

Two further Hullzellenbleche were pretreated as in Example 1 and then brightly coated or dickverkupfert, but without forming a barrier layer in an electroless copper immersion bath. It was intended to demonstrate the importance of electroless copper plating and the copper barrier layer, as well as the need for a copper barrier layer for further galvanic treatment. On the cleaned sheets, a high-gloss bright copper layer or high-gloss thick copper layer could be deposited, which, however, showed no base material adhesion. Already after the removal of the sheets from the acidic electrolyte a clear blistering was to be recognized. The Copper layers peeled off during subsequent drying with compressed air at 2 bar over a large area. The remainder of the copper layers could then be scraped off with a fingernail. Therefore, no further coating was done. These copper layers were not commercially usable. Comparative Examples 4 and 4a for costly copper plating with conventionally produced barrier layer:

Two further Hullzellen sheets 4 and 4a were first pretreated as in Example 1. The sheet 4a of Comparative Example 4a was additionally pickled after hot degreasing and rinsing with water and cathodically degreased to readjust the conventional process used in industry: The pickling of the second sheet was carried out with 5% sulfuric acid at room temperature for 30 seconds , After pickling, the sheet was rinsed again in city water and then degreased electrolytically. The degreasing was carried out cathodically in aqueous solution of 10 g / L KOH, 30 g / L sodium silicate, 10 g / L pyrophosphate and 1 g / L wetting agent at 2 A / dm ² and 30 ° C for 3 minutes. As a result, an additional cleaning effect compared to the sheet 4 was achieved.

Thereafter, the two cleaned sheets were not subjected to an electroless dip treatment, but in a galvanic process with a commercially available cyanide alkaline copper electrolyte of about 15 g / L Cu, about 50 g / L sodium cyanide, about 50 g / L sodium hydroxide solution, wetting agent, Brightener and other additives treated. The galvanic copper plating to form a barrier layer was carried out at 1 A / dm ² and 50 ° C for 5 minutes. This required approximately five times the time for the formation of the galvanically produced barrier layer for a specific layer thickness, as in the case of the electroless copper plating of the barrier layer according to the invention. The coated with a copper barrier layer sheets showed high adhesion, with sheet 4 and sheet 4a after cyanidic copper plating a matte surface without gloss showed without a bright copper layer was applied. The layer thickness of the barrier layers was on the side facing the anode, depending on the prevailing in the Hull cell anode distance extension 1, 2 - 2.5 pm. The copper barrier layers could not be scraped off with a fingernail. The crosshatch adhesion test was passed with GTO. A bending of the Hullzellenbleches over 180 ° was possible without Schichtabplatzungen at the Biegein- nen- and Biegeaußenkante. The applied barrier layer was ductile, almost nonporous, crystalline, and showed slight internal tensile layer stresses.

The layer thickness of the barrier layers was on the rear side facing away from the anode, which can be achieved barely or not by the field lines of the current, depending on the prevailing in the Hull cell anode distance extension and scattering ability of the cyanide, galvanic Verkupfer- rungsbad 0.06 and 1, 4 pm, but increased to the outer edges of the sheet. In the middle of the sheet was on the back of an area of about 2.3 x 1, 8 cm, which had not been coated with copper at all, so that a bare spot was visible. Even on the back, the copper barrier layers could not be scraped off with a fingernail.

Subsequently, the sheets were galvanized in a conventional acidic high-gloss copper bath at 2 A / dm ² at a temperature of 35 ° C for 15 minutes. It was striking that immediately after the galvanic bright copper plating, the area in the middle of the back of the sheet, which had not previously been provided with a cyanidically produced barrier layer, had a dull, gritty, streaky, slightly blackish copper layer. Since no barrier layer was present in this area, a pickling attack on the base material took place in the acidic bright copper plating bath at this point and in turn initiated a sedimentation. Thereafter, the sheets were rinsed again with city water and dried. This cyanidically produced copper barrier layer could also be followed directly by a bright nickel plating instead of the bright copper plating. The sheet 4 thus treated showed on the front side a shiny copper layer which had excellent adhesion. The additionally treated sheet 4a showed on the front a high-gloss copper layer, which also had excellent adhesion. On the back side of both sheets, the applied glossy copper layer also exhibited excellent adhesion at the points which could previously be provided with a cyanidically prepared copper barrier layer. In the central area on the back of the sheet, where due to the field line distribution of the current no barrier layer could be applied, peeled off the resulting copper layer in the subsequent drying with compressed air at 2 bar over a large area. The remainder of the copper layer in this area could then be easily scraped off with a fingernail. Therefore, no further coating was done. This copper layer on the back of the sheet was not commercially usable. The sheet 4a showed despite complex production no advantages compared to the plate 4th

Examples 5 and Comparative Examples 5 to influence the range of parts: To test the performance of the pretreatment products Gardobond ^® CU 7600 and Gardobond ^® CU Chemetall GmbH barriers scored 7602 to the the in a Electroplating operating range of parts to be treated and especially to thereby Due to the better handling, different sections of various machine, construction and spring steel alloy specimens for the purpose of increasing the corrosion protection and / or optical finishing according to the methods of Examples 1 and 2 or treated according to the methods of Comparative Examples 3, 4 and 4a. In the treatment according to the invention of the various parts according to the methods of Examples 1 and 2, the same high-quality properties and advantages were obtained in all parts as in Examples 1 and 2. Here, the parts after the galvanic treatment in the bright copper electrolyte or thick copper electrolyte well adhering and well-formed glossy high-gloss copper layers or high-gloss thick copper layers. In the interior of the pipe, where galvanic coating could not be successful, the currentless use of Gardobond ^® CU 7600 or Gardobond ^® CU 7602 for the production of barrier layers prevented uncontrolled cementation during the electroplating process with corresponding layer flaking. Also in the interior of the pipe were high-gloss, well-adhering copper layers. The dip was not polluted. All properties of all copper layers were high quality and impeccable. The processes were also particularly fast, simple, inexpensive, without much energy and without problems.

Again, in the treated by the method of Comparative Example 3 parts, a completely insufficient adhesion of the bright copper layer or the thick copper layer on all alloys. In hollow parts such as pipe sections, which can not be achieved due to the effect of a Faraday see cage inside with electricity, in addition, showed a very rough, grainy and gritty non-stick copper layer. This partly dissolved already during the electroplating process in the electrolyte and polluted it accordingly.

In the case of the parts treated according to the methods of Comparative Examples 4 and 4a, this was also to a lesser extent apparent: Depending on the scattering power of the cyanide electrolyte and on the depth of part o- the geometry or length of the pipe section. At the sites not accessible by electricity, due to the effect of a Faraday cage, such as inside the tube, a barrier layer could not be produced with a cyanide electrolyte for treatment in an acidic high gloss copper bath. As a result, when immersed in the acidic acid electrolyte or thick-film electrolyte in places without barrier again uncontrolled sedimentation initiated, which in turn had a non-adhesion of the layer at these points result and the electrolyte heavily soiled and subsequent electroplating baths such as a high gloss nickel bath could have been polluted. The treated according to Example 4 workpiece sections showed a shiny, according to Example 4a a high-gloss copper surface.

In addition, in all of Examples 1, 2, 4 and 4a, the cross-cut adhesion test, as far as possible by the part geometry, was passed with GT0. Bending of the test section sections over 180 °, also as far as it was possible by the part geometry, was possible without layering of the inner and outer edges of the bend. The applied barrier layer according to Examples 1 and 2, regardless of the geometry of the parts had a layer thickness, depending on the base material, between 1, 1 and 1, 6 pm, wherein the copper plating distributed evenly at all points of the parts. The barrier layers were extremely ductile, pore-free, fine-crystalline and without internal layer stresses.

Depending on the geometry of the parts, the barrier layer applied according to Examples 4 and 4a had a layer thickness of 0 m at locations where, owing to the action of the Faraday cage, the current required for the deposition was not provided and therefore no copper deposition took place. A layer thickness of up to 4.6 pm was deposited on sites which were well supplied with electrolysis, the copper plating being distributed unevenly on the workpieces, depending on the anode spacing and correspondingly increasing current density. In addition, those of Examples 4 and 4a applied barrier layers ductile, almost free of pores, crystalline and showed slight internal tensile layer stresses.

Comparative Example 6 for Conventional Screw Production:

High-grade steel screws are partially conductively heated to set certain strength parameters and then hardened by quenching. To increase the electrical conductivity, it is therefore necessary to provide the screws with a highly electrically conductive copper layer as a conductive layer, which should have a layer thickness in the range of 1 to 5 μm. Sample parts of such screws were treated in the process of mass production of such screws according to the prior art as follows:

1 . Hot / decoction greases in 10 g / L NaOH, 30 g / L sodium pyrophosphate and 5 g / L wetting agent at 70 ° C for 3 minutes,

2. rinse in deionised water,

3. pickling in HCl of about 15%, at room temperature over 3 minutes,

4. Rinse in demineralised water,

5. Electrolytic degreasing in 10 g / L KOH, 30 g / L sodium silicate, 10 g / L pyrophosphate and 1 g / L wetting agent at 2 A / dm ² and 30 ° C for 3 minutes for cathodic cleaning,

6. rinse in demineralised water,

7. pickling in 3% HN0 ₃ at room temperature for 10 seconds,

8. Rinse in demineralised water and

9. Cyanide alkaline electrolytic copper plating with aqueous

Solution based on about 15 g / L Cu, about 50 g / L sodium cyanide, about 50 g / L sodium hydroxide, wetting agents, brighteners and other additives

1 A / dm ² and 50 ° C for 10 minutes, with a layer thickness of 3 - 5 pm was achieved. All parts treated in this case had a very well-adhering copper layer, with the copper pad a conductive heating at low and greatly reduced resistance was easily possible. The screws treated according to Comparative Example 6 showed a matte copper surface. Bending of the test screws over 90 °, as far as it was possible by the geometry of the parts, was also possible without layer flaking at the inside and outside edges of the bend. The conductive layer, which was galvanically applied from a cyanidic bath, was ductile, almost free from pores, crystalline and showed slight internal tensile stresses in the copper layer. Inventive Example 7 for screw production according to the invention:

Just such screws were hot degreased, rinsed, pickled, rinsed again as in Comparative Example 6 and then treated without further steps directly without current with the coppering bath based on Gardobond ^® CU 7602 as in Example 1 for 0.5 minutes at 30 ° C. Unlike Comparative Example 6 was not rinsed here with demineralised water and not degreased electrolytically and not dekapiert. Instead of cyanide alkaline electrolytic copper plating, the electroless copper plating bath of Example 1 was used. Nevertheless, the screws were provided with an adherent, clearly shining copper layer of 1, 6 to 1, 8 pm thick. The conductive heating of the copper-plated screws succeeded without any problems since the copper layer had a particularly low electrical resistance. The treated according to Example 7 screws showed a shiny copper surface. Bending the test screws over 90 °, as far as it was possible by the part geometry, was possible without Schichtabplatzungen on Biegeinnen- and Biegeaußenkante. The applied by the novel process conductive layer was particularly ductile, non-porous, fine crystalline and without internal stresses. All properties of all copper layers were high quality and impeccable. The manufacturing process was particularly fast, particularly simple, particularly safe, inexpensive, without much energy, easily and in a non-toxic and environmentally friendly manner compared to prior art methods. The copper layer, in contrast to the cyanide electrolytic copper layers of the prior art, completely free of pores and therefore higher quality and more electrically conductive.

Inventive Example 8 for chemically varied screws preparation: high screws were treated as in Example 7, but with the difference that was used as an electroless dip Gardobond ^® CU 7600 with a composition and 0.5 minutes at 30 ° C as in Example 2. FIG.

All parts treated in this way had a very well-adhering copper layer of light gloss, from 1, 3 to 1, 5 pm thick and with a low electrical resistance as in the copper-plated screws of Example 7. With this copper layer, a conductive heating of the screws was easily and well possible. Bending of the test screws over 90 °, as far as it was possible by the geometry of the parts, was also possible without layer plaque on the inside and outside edges of the bend. The applied by the novel process conductive layer was particularly ductile, non-porous, fine crystalline and without internal stresses.

All properties of all copper layers were high quality and impeccable. The manufacturing process was particularly fast, particularly simple, cost-effective, without much energy and without problems. The conductive layer could be applied in a particularly safe, non-toxic and environmentally friendly manner compared to prior art methods. The copper layer is in contrast to the cyanide electrolytic See copper coatings of the prior art non-porous and therefore high-quality and electrically conductive.

Comparative Example 9 for an attempt to make a conductive layer on steel screws with a conventional, acid bright copper plating process:

Additional screws were treated as in Example 6, however, the cyanide alkaline electrolytic copper plating step was performed by a cyanide-free and reducing agent-free acidic electrolytic luster coating step based on about 200 g / L CuS0 ₄ x 5 H ₂ O and about 60 g / LH ₂ S0 ₄ technically pure and about 80 mg / L NaCl and other leveling and gloss-forming organic additives at 2 A / dm ² and a deposition rate of about 0.5 pm / min at 30 ° C for 5 minutes replaced. The composition was identical to that of the bright copper plating bath, which was also used in further examples for further processing to apply a bright copper layer to an existing barrier layer.

All parts of Comparative Example 9 showed a high-gloss copper layer, but had no liability. Conductive heating with low resistance was not possible. A further processing of the screws resulting from Comparative Example 9 was also not possible because the deposited copper layers already detached during drying in a drum. Thus, the required low electrical resistance of the screws for subsequent curing by conductive heating to about 680 ° C could not be achieved. Hardening and quenching these screws was not possible. Comparative Example 10 for a Conventional Method of Manufacturing Printing Rollers:

A steel roller was treated as follows: 1 . Degreasing in 10 g / L NaOH, 30 g / L sodium pyrophosphate and 5 g / L wetting agent at 70 ° C for 3 minutes,

2. rinse in deionised water,

3. rinse in deionised water,

4. Electrolytic nickel plating by impact nickel strike with 200-250 g / l NiCI ₂ and 200 g / L HCl at 2 A / dm ² and 30 ° C over 40 minutes, for a layer thickness of 30 to 40 pm, from the inside increasingly outward

5. rinse in demineralised water,

6. rinse in demineralised water,

7. Electrolytic acidic thick copper plating as 350 pm thick engraving pad at 5 A / dm ² and 30 ° C for 240 minutes.

A further processing of the treated according to Comparative Example 10 roll was easily performed. The applied with the conventional method nickel barrier layer generated a very good primer for the following Dickverkupferung. The Dickverkupferung could not be scraped off with the fingernail. The crosshatch adhesion test was passed with GT0. As an additional stress test, the applied thick copper layer of the gravure roll was ground on a cylindrical polishing machine of the manufacturer Sanko Kokai with a 1000 grit and then polished to a high gloss. An engraving and engraving a gravure pattern in the polished thick copper plating was easily possible. The applied Dickverkupferung was pore-free and fine crystalline.

Inventive Example 1 1 for the copper plating of printing cylinders: a roller was treated as in Example 10, but the presence was schlagvernickelungsprozess of Comparative Example 10 by electroless Kupfertauchbadbehandlung based on Gardobond ^® CU 7602 with a bath preparation, and with a process sequence as in Example 1 replaced. In addition, after degreasing and stop coupons only once again flushed and thus achieved a reduction of Spülwasserverbrauchs by 40%. The treatment time of the printing roller could be reduced to 0.5 minutes for applying the barrier layer of 40 minutes as described in Comparative Example 10. The applied copper barrier layer had uniformly distributed over the entire roll a layer thickness of 0.8 to 0.9 pm. The applied copper barrier layer was also shiny. Thus, the treatment time was reduced by 80 times and the amount of metal applied by 40 times. It is thus shown that it is possible with the method according to the invention to replace a conventional, complex, toxic nickel plating process by a significantly more environmentally friendly, only slightly harmful, significantly simpler and faster copper plating process.

A further processing of the treated according to Comparative Example 1 1 pressure roller was easy to carry out. The copper barrier layer applied by the method according to the invention provided an outstanding primer for the subsequent thick copper plating. The thick copper plating could not be scraped off with the fingernail. The cross hatch adhesion test was passed with GT0. As an additional stress test, the applied thick copper layer of the gravure roll was ground on a cylindrical polishing machine of the manufacturer Sanko Kokai with a 1000 grit and then polished to a high gloss. An engraving and engraving a gravure pattern in the polished thick copper plating was easily possible. The applied Dickverkupferung was pore-free and fine crystalline. To re-examine the adhesion of the coating on the base material, the pressure roller was then turned off on a test print on a lathe with a feed of 0, 1 mm. The applied copper-plating layer could be cut without any cuts, section by section, without losing any adhesion. Inventive Example 12 on chemically varied copper-plated pressure roll:

A roller was treated as in Example 10, but was in this case, the Anschlagvernickelungsprozess of Comparative Example 10 by electroless Kupfertauchbadbehandlung in Gardobond CU ^® 7600 with a bath preparation described in Example 2 and with a process sequence as in Example 2 replaced. In addition, after degreasing and stop copper plating only once rinsed, thus achieving a reduction of Spülwasserverbrauchs by 40%. The treatment time of the pressure roller could be reduced to 0.5 minutes for applying the barrier layer of 40 minutes as described in Comparative Example 10. The applied copper barrier layer had a layer thickness of 0.7 to 0.9 pm, which was distributed evenly throughout the entire roll. The applied copper barrier layer showed a slight sheen. Here, the treatment time was reduced by 80 times and the amount of metal applied by 40 times. It is thus shown that it is possible with the method according to the invention to replace a conventional, complex, toxic nickel plating process by a significantly more environmentally friendly, only slightly harmful, significantly simpler and faster copper plating process.

A further processing of the treated according to Comparative Example 12 pressure roller was easily performed. The copper barrier layer applied by the method according to the invention provided an outstanding primer for the subsequent thick copper plating. The thick copper plating could not be scraped off with the fingernail. The cross hatch adhesion test was passed with GT0. As an additional stress test, the applied thick copper layer of the gravure roll was ground on a cylindrical polishing machine from Sanko Kokai with a 1000 grit and then polished to a high gloss. An engraving and pricking A gravure pattern in the polished Dickverkupferung was easily possible. The applied Dickverkupferung was pore-free and fine crystalline.

To recheck the coating adhesion to the base material, this pressure roller was then turned off on a rotary press on a rotary machine with a feed of 0.1 mm. The applied copper-plating layer could be cut off section by section without any problems, without losing adhesion.

Comparative Example 13 for Copper Plating a Pressure Roller Without a Barrier Layer

Another cylinder was used without the application of a precoat such as e.g. a barrier layer according to Comparative Example 3 directly after the degreasing and rinsing acidic electrodeposited thick.

Since a barrier layer was missing, when immersed in the acidic thick copper plating electrolyte, uncontrolled sedimentation started, so that the layer did not adhere and heavily contaminated the electrolyte. The copper layer partially dissolved already during the coating. Further processing of the treated pressure roller was therefore not possible.

Example 14 According to the Invention for Coppering Zinc Die Castings:

Various zinc die castings such as e.g. Press studs, pushbuttons, switches, window fittings and model articles made of different zinc alloys such as ZL0400, ZL0410 or ZL0430 were subjected to the treatment described below in order to simulate the part and especially the alloy spectrum of a galvanizing plant to be treated:

1 . Mild alkaline degreasing in 10 g / L Na ₂ C0 ₃ , 5 g / L sodium pyrophosphate and 5 g / L wetting agent at 70 ° C for 3 minutes,

2. rinse in city water, 3. picking in 5% HF at room temperature for 10 seconds,

4. rinse in city water,

5. Electroless copper plating neutral in 200 g / L Gardobond ^® 7602 CU without sulfuric acid, but with 10-fold increased amount of brightener, at pH values ranging from 6.5 to 7 and 30 ° C for 30 seconds,

6. rinse in city water,

7. Acid glaze copper at 2 A / dm ² and 35 ° C over 15 minutes.

The applied barrier layer had a layer thickness of between 0.3 and 0.4 μm, regardless of the part geometry, with the copper plating being distributed uniformly over the workpiece surfaces. The barrier layers were very ductile, nonporous, finely crystalline and free of internal layer stresses. The zinc die-castings coated with the copper barrier layer according to the invention showed a high adhesion and a clearly glossy surface, without a bright copper layer being applied. The copper barrier layers could not be scraped off with the fingernail. The crosshatch adhesion test was passed with GT0. Bending of the parts over 90 ° was possible without Schichtabplatzungen at Biegeinnen- and Biegeaußenkante.

Subsequently, the zinc die castings were electroplated in a conventional acid high gloss copper bath at 2 A / dm ² at a temperature of 35 ° C for 15 minutes. The zinc die castings previously provided with the barrier layer applied in accordance with the present invention exhibited a high gloss glossy copper layer which had excellent adhesion, as confirmed by crosshatching and bending tests. In addition, by using tap water instead of the demineralized water used in the conventional cyanide electroplating copper plating process, the process of the present invention has been able to reduce the cost of flushing by more than 60%. In the inventive treatment of the various parts by the method of Example 14 resulted in all parts the same high quality properties as in Examples 1.

All properties of all copper layers were high quality and impeccable. The processes were also particularly fast, simple, inexpensive, without much energy and without problems. In addition, a pickling attack and a Sudabscheidung was avoided by the acidic copper bath on the base material.

Comparative Example 15 for the Copper Plating of Zinc Die Castings Without Barrier Layer:

Similar zinc die castings as in Example 14 were treated as in Example 14 except that the electroless copper plating in the dipping bath was omitted without substitution, so that no barrier layer was formed.

These zinc die castings did not show a deposited copper layer after the bright copper plating process. Since no barrier layer was present, the metallic surface was very strongly pickled during plating in the acidic bright copper electrolyte, which made metal deposition in the galvanic copper plating impossible. In addition, all workpieces were destroyed by very strong pickling. The introduction of zinc foreign ions into the electrolyte led to the deterioration and finally the destruction of the bright copper electolyte.

Comparative Example 16 for conventional alkaline copper plating of zinc die castings:

Similar die-cast zinc parts were coated as in Example 14, but the electroless plating treatment by a conventional alkaline cyanide copper plating process became 1 A / dm ² and 55 ° C 5 minutes to replicate the prior art zinc die casting manufacturing process.

Depending on the geometry of the part, the applied barrier layer had a layer thickness between 0 and 3.9 μm, whereby the copper plating was distributed unevenly over the workpiece surfaces depending on the anode distance and correspondingly increasing current density. Due to Faraday's cage and the geometry of the parts, copper deposition did not occur at sites that could not be reached with the necessary current for the deposition of copper from cyanide electroplated electrolytes. In addition, the barrier layers applied were ductile, almost nonporous, crystalline, and exhibited slight internal tensile layer stresses. The zinc die-cast parts coated with a copper barrier layer exhibited high adhesion, but after the cyanidic electrodeposition, a matte surface without gloss since no bright copper layer had been applied yet. The copper barrier layers could not be scraped off with the fingernail. The crosshatch adhesion test was passed with GTO. Bending of the parts over 90 ° was possible without Schichtabplatzungen on Biegeinnen- and Biegeaußenkante.

Subsequently, the zinc die castings were electroplated in a conventional acid high gloss copper bath at 2 A / dm ² at a temperature of 35 ° C for 15 minutes. It was striking that at locations which had not been provided with a copper barrier layer due to the geometry of the parts and the Faraday cage, gassing began immediately after immersion in the galvanic bright copper plating bath. Here, a pickling attack on the base material was carried out by the acidic solution of the bright copper bath. He led to its destruction. After higher throughput, the introduction of zinc foreign ions led to the destruction of the acidic copper bath. The zinc die-cast parts, which had been previously provided with a copper barrier layer, showed a high-gloss copper layer, which had excellent adhesion. This was confirmed by crosshatching and bending tests.

By using deionized water instead of used in the present process Gardobond ^® CU 7602 favorable urban water high-gloss flawless bright copper layers could be deposited with excellent adhesion as well.

This procedure is also more stressful and, due to more process steps, significantly longer plating times and significantly increased energy expenditure much more complex than in a process according to the invention.

Example 17 According to the Invention and Comparative Examples 17 and 17a for Galvanized Steel Sheets

Zinc-coated steel sheet sections were treated by the methods as in Examples of the Invention and Comparative Examples 14 to 16.

It was found that a composition based on the product Gardobond ^® CU 7602 could be used to achieve excellent results in a simple and fast manner without current. The copper layers were adherent, clearly glossy and ideal for further processing. However, when cyanidic electrolytic copper plating of the prior art was used instead (Comparative Example 17), this environmentally unfriendly poisonous method made it possible to obtain good copper plating with increased expense, which gave adherent matte and readily processable copper layers. The adhesion of the applied layers was determined by cross-cut, wipe and bending tests according to DIN EN ISO 2409, according to DIN EN ISO 1519 or ASTM 2794 checked. The coatings of Example 17 and Comparative Example 17 showed good adhesion.

In the electrolytic use of an acidic bright copper bath (Comparative Example 17a) was due to the low pH of about 1, a pickling attack on the galvanizing, which was completely dissolved and destroyed. This led to the entry of foreign ions in the coppering bath and also led to its heavy contamination. The bathroom could not be used thereafter. No copper layer was formed. The sheet metal sections had to be discarded. This process is particularly complex and does not work.

Example 18 according to the invention to different composition copper plating baths

Coppering baths were used as in Examples 1 and 2, but more varied chemically in their composition. Hull cell sheets made of ST2 steel were then cleaned and treated as in Examples 1 and 2.

Table 1: Variation of bath composition and bathing conditions, with the total amount being e.g. be given to copper, sulfuric acid, brightener or Beizinhibitor

GB ^ stands for Gardobond ¹⁰ of Chemetall GmbH.

^* ) The trial times were too short to notice significant changes in Fe ²⁺ content.

Table 1 illustrates the wide range of chemical composition and bath temperature of the copper plating solution as well as treatment times to produce good copper layers. In the coating of ferrous materials, the pH value could be varied between 0, 1 and 1 without negative influences, while it could be varied between 6.5 and 7.0 without negative influences for zinc-rich materials. The bath temperature could be varied without negative influences between 15 and 95 ° C, if the bath composition, or / and the treatment time were adjusted. The duration of the electroless plating could be varied between 3 seconds and more than 30 minutes without negative influences, if the bath composition and / or the bath temperature were adjusted. The adhesion of the applied layers was checked by crosshatch, wipe and bending tests according to DIN EN ISO 2409, according to DIN EN ISO 1519 or according to ASTM 2794. All examples showed good adhesion.

It was found in these experiments that lower concentrations or / and shorter coating times are sufficient for higher concentrations, in particular for copper and / or for acid. Conversely, it was found that for lower concentrations, in particular of copper or / and of acid, higher temperatures or / and longer coating times, temperatures of at least 15 ° C. or / and coating times of at least one minute are advantageous in order to form pore-free and well-adhering copper layers. It was surprising how successful and flexible electroless copper could be. It was always not only process advantages over copper coatings of the prior art, especially in hollow bodies.

Table 2: Tabular data for Examples and Comparative Examples 1 to 17 / 17a: *) strong pickling attack on the parts that did not have a closed cyanidically electrolytically produced copper barrier layer due to the Faraday cage

The layer thickness in the electrolytic coating shows a large range of variation, depending on how the current density distributed due to the existing part geometry on the workpiece and accordingly power is available for Metallab divorce.

A thick layer may alternatively be applied to the gloss layer. However, this results in significant differences in ductility, brittleness, gloss level and layer thickness of the electrolytically applied layer.

Claims

Claims:

1 . A method of treating a metallic surface of an article with an aqueous copper plating solution, characterized in that on clean metallic surfaces of the article or after pretreatment on cleaned metallic surfaces a first copper plating solution which is free of cyanide and free of intentionally added strong copper Reducing agent which has a potential with values of less than -0.6 V, or which is free from intentionally added reducing agent, is used for forming a first copper layer or copper alloy layer as a barrier layer and / or as a conductive layer without current.

2. The method according to claim 1, characterized in that an article made of a ferrous material, zinc, from a zinc alloy o / / and is treated from a tin material.

3. The method according to claim 1 or 2, characterized in that stainless steel surfaces are copper-plated, wherein for pickling before the coppering at least one non-oxidizing acid is used for the previous activation and wherein for coppering, if necessary, additionally an electrically conductive contact with a less precious metal than Stainless steel is used.

4. The method according to any one of the preceding claims, characterized in that an article made of a ferrous material, zinc, a zinc alloy and / or a tin material is treated with the proviso that the first copper plating solution in the treatment of an article of iron or steel, optionally with the exception of stainless steel, contains no complexing agent.

5. The method according to any one of the preceding claims, characterized in that a first copper plating solution cyanide-free for the formation of a barrier layer and / or a conductive layer on a less noble metallic surface is used as copper.

6. The method according to any one of the preceding claims, characterized in that the first copper plating solution contains no intentionally added reducing agent and no strong and possibly also no weak complexing agent with the exception of dissolved out of the surfaces and / or leached out ions.

7. The method according to any one of the preceding claims, characterized in that the first coppering solution contains no intentionally added complexing agent or no complexing agent.

The method of claim 6, characterized in that the first copper plating solution contains ions having potential values in the range of -0.4 to -1.8V.

9. The method according to any one of the preceding claims, characterized in that the copper plating solution for electroless formation of

Barrier layer and / or conductive layer at least one copper compound and at least one brightener, at least one acid o- / / and at least one pickling agent.

10. The method according to any one of the preceding claims, characterized in that the copper plating solution for electroless formation of

Barrier layer and / or conductive layer additionally contains at least one pickling inhibitor and optionally also a pickling amplifier.

1 1. Method according to one of the preceding claims, characterized in that the copper plating solution for electroless formation of the barrier layer and / or conductive layer additionally contains at least one brightener.

12. The method according to any one of the preceding claims, characterized in that the pH of the first copper plating solution for zinc rich or tin-rich metallic surfaces in the range of 4 to 8.5 or for iron-rich metallic surfaces is less than 5.

13. The method according to any one of the preceding claims, characterized in that after the formation of the barrier layer and / or conductive layer at least one cover layer as a glossy layer is applied electrolytically or at least one layer as a thick layer chemically or electrolytically.

14. The method according to any one of the preceding claims, characterized in that electrolessly by dipping, spraying, rolling, brushing, casting, by sponge application and / or by tampon application and / or thereafter coated.

15. The method according to any one of the preceding claims, characterized in that the object provided with a barrier layer undergoes at least one subsequent surface treatment.

16. The method according to claim 13, characterized in that the object provided with an electroless copper layer is at least once treated by electroplating, painted at least once or coated with a powder coating or with a cathodic dip (KTL) or is joined together with another object.

17. An article with a barrier layer and / or a conductive layer, which is prepared according to one of claims 1 to 16.

18. Use of a provided with a barrier layer and / or a conductive layer article, produced according to one of claims 1 to 16, as wire, profile, pipe or rod, as a welding wire, as Be shock, element or connecting element, as an element of an apparatus, a machine, a household appliance, an electronic article, an electronics article or toy, as an ornament, as an element for a clock, as a housing, linkage, bracket, mounting plate or cladding, as an element in the apparatus construction, Mechanical engineering, automotive or transport, as a mechanical functional part or for a metallic object to be hardened or as a screw.

19. Use of a provided with a conductive layer article for producing a more electrically conductive article, for conductive heating and / or curing of the metallic article.