DE102011080745A1 - Process for the metallic coating of metallic surfaces by electroless copper plating - Google Patents

Abstract

The invention relates to methods for treating a metallic surface of an object with an aqueous copper plating solution, with which a first copper plating solution, which is cyanide-free and free of strong reducing agent, is formed on clean metallic surfaces of the object or after pretreatment on cleaned metallic surfaces first copper layer or copper alloy layer is used as a currentless barrier layer and / or as a conductive layer, and the use of the articles produced by the method according to the invention.

Description

The invention relates to methods for treating a metallic surface of an article - in particular for treating the metallic surface of an article having a surface made of a ferrous material, a zinc material or / and a tin material such. As zinc and / or 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, cheaper and more environmentally friendly method. 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, sputtering, nickel plating, cadmium plating, chrome plating, staining, 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. Nickel plating can then be followed, for example, by chrome plating, silver plating, platinizing, rhodium plating or gold plating. 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 follow on a nickel topcoat at least one other type of topcoat such. B. at least one cover layer of gold, platinum, rhodium, silver or chromium, wherein all cover layers are usually applied electrolytically and mostly from acidic aqueous solutions. The cover layers can, for example, usually be bright copper layers with layer thicknesses in the range of 3 to 50 μm and preferably in the range of 5 to 20 μm, thick copper layers with layer thicknesses usually in the range of 50 to 5000 μm and preferably in the range of 80 to 500 μm, bright nickel layers with layer thicknesses in the range of 3 to 20 microns and / or thick nickel layers with layer thicknesses usually be in the range of 30 to 250 microns.

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 skilled person speaks 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" 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. Therefore, all reducing agents used in chemical copper or nickel baths have potentials of at most -0.6 V, or preferably at most -0.8 V, and more preferably at most -1 V. The potential data refer to measurements with one standard hydrogen electrode. And these reducing agents are considered strong reducing agents, i. H. have potential values of at most -0.6V and often values in the range of -3 to -1V.

Electroless baths are usually the galvanic = electrolytic and / or the electroless = chemical = strong reducing agent containing baths preferable because they lead to faster film formation at a lower workload and lower energy consumption than in electrolytic and electroless baths, as far as such layers can be formed at all powerless. But in many cases, the desired metal layers in a suitable layer quality can only be produced electrolytically, such as. Example, in an alkaline, cyanide electrolytic coppering, in an alkaline, cyanide-free electrolytic copper plating or in an acidic electrolytic nickel-strike process. Therefore, today almost always electrolytic, ie energetic and process engineering very much consuming, 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 z. B. required to an uncontrolled, usually poorly adhering sedimentation on the workpiece such. B. to avoid having a surface of a metal with more electronegativerem potential than copper from a solution with higher potential. Treating a workpiece with a surface z. 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 galvanizing companies, so go iron and / or analog z. As well as zinc after the redox reaction Oxidation: Fe → Fe ²⁺ + 2e ^- Reduction: Cu ²⁺ + 2e ^- → Cu with electron donation in solution. Then, metallic copper deposits on the surface in a non-adherent coating. Since so far only very thin, spongy, porous, hardly to not adherent layers can be deposited in this way, 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 the Sudabscheidung in motion. 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 thereby cause dull, gray, streaky, rough or / and porous 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, 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 used for the production of a barrier layer in industrial practice. Preferred, in in more than 85% of cases, 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, z. B. as at least one gloss and / or 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 barrier according to the invention also serves workpieces of any part geometry and possibly also with cuts and backstitches of a base material having a low electrochemical potential, such as iron and / or zinc and / or one of their alloys, Environmentally friendly, de-energized and high quality and cost-effective, effective and fast to coat the corresponding process of the prior art.

Therefore, when applying a barrier layer and preventing sedimentation, it is still necessary today, and even before further galvanization, to make workpieces that are made of a material having a very low potential and, in particular, decorative or technical, first electrolytically, d. H. using electricity, with a coating of a cyanide alkaline electrolyte 1.) or rarely instead of a bath of a purely alkaline complexing agent 2.) to coat. Since the metal deposition of a metal-cyano complex at 1.) or at 2.) z. B. 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 gives no or poorly adhering precipitates which 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 production of welding wire or 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 because the nobler metal precipitates as a brew in a non-adherent 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 coppered 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-reliable 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. You therefore need a separate sewage system and - treatment and 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, attempts are made repeatedly to use less harmful complexing agents and complexes for coppering baths. Weak complexes such. As a citrate, hydroxo, ammonium, acetate, phosphate and diphosphate complex disintegrate in acidic and in alkaline solutions. Strong complexes such. B. Ethylenediaminetetraacetat (EDTA) are stable in acidic and alkaline solutions, but are environmentally unfriendly because of their wastewater hazard. They are therefore rarely used commercially.

• 1.) Cyanidische alkalische elektrolytische Verkupferung: Üblicherweise, in mehr als 85% der Fälle, werden diese Sperrschichten heute in der großindustriellen Praxis insbesondere für die Grundmaterialien Eisen, Zink oder/und deren Legierungen noch immer aus cyanidischen alkalischen Verkupferungselektrolyten aufgebracht. Deren wässerige Zusammensetzungen und Behandlungsbedingungen sind oft folgendermaßen: Das Verkupferungsbad enthält etwa 50 g/L CuCN, etwa 75 g/L NaCN, etwa 40 g/L NaOH und falls nötig glanzbildende Additive, aber üblicherweise keine Reduktionsmittel und keine Säure. Sein pH-Wert liegt bei etwa 12. Es wird bei etwa 40°C und bei einer Stromdichte von etwa 1 A/dm² über etwa 10 Minuten gearbeitet.

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 applied today from cyanide alkaline copper plating in large industrial practice, especially for the base materials iron, zinc and / or their alloys. 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.

A metal deposition takes place according to the following equations: [Cu (CN) ₃ ] ² - → [Cu (CN)] + 2CN ^- [Cu (CN)] + e ^- (from external current source, rectifier) → Cu + CN ^-

Such cyanide-containing alkaline electrolytic copper plating baths can also be used to change the technical properties of a base material for certain uses, eg. B. for the production of a barrier layer before nitriding steel or for the production of a layer with lower electrical resistance as z. B. for a conductive heating of workpieces such. B. screws is needed. The advantage here is a better corrosion protection and / or a better electrical conductivity than the base material has on its own.

• 2.) Cyanid-freie, alkalische, elektrolytische Verkupferung: Cyanid-freie, alkalische Bäder sind nicht hochgiftig. In Cyanid-freien alkalischen Kupferbädern zerfallen die Badbestandteile üblicherweise ebenfalls nicht in die entsprechenden Ionen. Daher kann ein Grundwerkstoff von elektronegativerem Potenzial als Kupfer nicht stromlos, jedoch nur bei schwieriger Prozessführung und nach kritischer Vorbehandlung mit Strom verkupfert werden. Daher werden heute vereinzelt elektrolytische Kupferbäder alkalisch Cyanid-frei zum Auftragen einer Sperrschicht eingesetzt. Die Vorbehandlung des Grundmaterials sowie die Prozessführung sind deshalb jedoch wesentlich kritischer oder aufwändiger als bei 1.). Bisher ließen sich auch nicht alle Grundwerkstoffe damit behandeln. Auf die Vorbehandlung der Werkstücke ist größte Sorgfalt zu legen.

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 these must be heated to at least 50 ° C and that the electrons required for metal deposition must be supplied by an external rectifier (= energy-intensive).

• 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 critical pretreatment. 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 in 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 PO ₄ if necessary to adjust the pH to about 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.

• 3.) Elektrolytisches, galvanisches Nickel-Strike-Bad: Für Werkstücke aus Eisen oder/und deren Legierungen werden heute auch sogenannte Nickel-Strike-Bäder zum Auftragen einer Sperrschicht verwendet.

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, then parts of zinc die casting due to their poor conductivity not in the galvanic drum process, but only galvanically coated in the elaborate frame method. 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 to apply a barrier layer.

Rarely, in about 3% of cases, nickel strike baths are 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. They may contain z. B. NaCl as pickling and / or if necessary gloss-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 less than 0.5 or at concentrations of 200 to 250 g / L NiCl ₂ and about 40 g / LH ₃ BO ₄ at pH's of about 4 at about 40 ° C for about 5 minutes.

• 4.) Mit einer sauren Glanz- oder Dickverkupferung kann zwar keine Sperrschicht erzeugt werden, sie wird jedoch genutzt, um hochwertige Kupferschichten zu bilden: Sie wird seit langem in der Galvanotechnik insbesondere für die Herstellung von dekorativen oder/und galvanoplastischen Beschichtungen verwendet. Werkstücke aus einem Grundmaterial mit elektronegativerem Potenzial als Kupfer ohne Sperrschicht können aufgrund der einsetzenden Sudabscheidung darin jedoch nicht behandelt werden.

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 on the entire system and the entire building has an effect. The sulfamate stop baths, which are sometimes used separately, reduce the high level of corrosion around the baths a little because of the lower chloride content, but they can not completely prevent the corrosion. 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 foreign substances, optionally including foreign ions, continuously z. B. by filtering to remove foreign substances such as metal particles to clean. 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 it is not possible to produce a barrier layer with acidic or thick copper plating, it is used to form high-grade copper layers. It has long been used in electroplating, in particular for the production of decorative and / or electroformed coatings. However, workpieces made of a base material with a more electronegative potential than copper without a barrier layer can not be treated due to the onset of sedimentation.

A bright nickel plating can only be done electrolytically in an acidic bath. A Glanzverkupferung can only be done electrolytically in an acidic bath economically. As 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 cost of the necessary, high-purity chemicals, their disposal problems, their critical handling and litigation, the very slow deposition rate and the low ductility and gloss level of the copper layers.

A Dickverkupferung or thick nickel plating can be done only 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 less 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 power is necessary: Depending on the method, application and base material approximately between 0.5 and 5 A / dm ² current density 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 Platinierung 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 the variants 1) to 3), produced by a comparatively complex, energy-consuming and slow and often after a very environmentally unfriendly process.

• a) Heißentfetten in wässeriger Lösung von 10 g/L NaOH, 30 g/L Natriumpyrophosphat und 5 g/L Netzmittel bei 60–95°C über 5–10 Minuten,
• b) Kaskadenspülen in VE-Wasser,
• c) Beizen je nach Anwendung und Grundmaterial – Eisenteile: 15%ige HCl und 1 g/L Netzmittel, ohne Beizinhibitor, bei Raumtemperatur über 5–15 Minuten, Zinkteile: 3%ige HF und 1 g/L Netzmittel, ohne Beizinhibitor, bei Raumtemperatur über 5–60 Sekunden,
• d) Kaskadenspülen in VE-Wasser,
• e) Elektrolytisches Entfetten mit kathodischer Schaltung des Gegenstandes: 10 g/L KOH, 30 g/L Natriumsilicat, 10 g/L Pyrophosphat und 1 g/L Netz-Mittel bei 0,5–2 A/dm², 1–5 V und 15–60°C über 0,5–5 Minuten,
• f) Kaskadenspülen in VE-Wasser,
• g) Cyanidisches Verkupfern in wässeriger Lösung bei 0,3–1,5 A/dm², 1–3 V, 60°C, Wirkungsgrad des Stroms η 70% und max. 0,3 μm/min über 5–15 Minuten mit: 50 g/L CuCN, 50 g/L NaCN, 40 g/L NaOH, 1 g/L Netzmittel, 3 g/L Glanzbildner oder Alkalisches Verkupfern in wässeriger Lösung bei 0,1–1,0 A/dm², 15–20 V, 60°C, Wirkungsgrad des Stroms η 90% und max. 0,25 μm/min über 5–15 Minuten mit: 15 g/L Cu, 50 g/L Pyrophosphat, 1 g/L Netzmittel, 3 g/L Glanzbildner und bei Bedarf verdünnter KOH oder verdünnter H₃PO₄ zur pH-Wert-Anpassung auf pH-Werte im Bereich von 8,5 bis 9,5,
• h) Kaskadenspülen in VE-Wasser.

A process still common today in the galvanic treatment, in particular of steel, zinc and / or 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 application and base material - iron parts: 15% HCl and 1 g / L wetting agent, without pickling inhibitor, at room temperature for 5-15 minutes, zinc parts: 3% HF and 1 g / L wetting agent, without pickling inhibitor 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 over 0.5-5 minutes,
• f) cascade rinsing in demineralised water,
• g) cyanide 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 μm / min for 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 μm / 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 PO ₄ for pH Value 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 microns. 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 microns to about 5 mm, but may u. U. several weeks electrolytic or electroless (= chemical) copper deposition condition. Workpieces with a complicated geometry of the part to be treated are rarely in an electroless dip such. In DE 20 26 698 A1 then treated again to subsequently apply a gloss or thick layer after an electrolytic cyanide copper plating. However, in the plating baths described there is always a strong complexing agent such. As cyanide, gluconate or ethylenediaminetetraacetate (EDTA) with appropriate environmental, Toxizitäts-, Abwasserbehandlungs- and treatment problems of needs. Examples of such complexing agents are amines and carboxylic acids such. As gluconic acid, lactic acid, tartaric acid and derivatives thereof such. Sodium gluconate, Rochelle salts, ethylenediamine, diethylenetriamine, diethanolglyoxime, 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 else 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 separation and bath heating, and without questionable wastewater treatment.

• a) 1. Kupferschicht elektrolytisch mit Cyanid,
• b) Spülen,
• c) 2. Kupferschicht hergestellt im stromlosen alkalischen Tauchbad, mit Cyanid oder mit einem anderen starken Komplexbildner,
• d) Spülen und
• e) Weitergalvanisieren.

DE 20 26 698 A1 teaches a production process

• a) 1. Copper layer electrolytically 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 in the in DE 20 26 698 A1 precipitation still obtained are relatively porous, since the previously known electrolytes in the alkaline pH range are very sensitive to inadequate parts cleaning and Badverunreinigungen and there for adhesion purposes still in addition a galvanic, alkaline, cyanide or a different alkaline prebath than Slip is necessary and only in parts with difficult part geometries an improvement compared to a treatment in a cyanide, 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.

Electroless metal deposition occurs when no further reducing agent is added to the solution by cementation or by flash 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.

How out N. Kanani: Copper layers: deposition, properties, applications, Eugen-G.-Leuze-Verlag Bad Saulgau 2000, p. 73/74 can be removed, it is still not possible to provide workpieces made of the basic materials iron, zinc and / or their alloys directly with a copper coating of acidic glossy and / or thick-film copper. Therefore, it is still necessary today, workpieces z. B. from the base materials iron, zinc and / or their alloys with a barrier layer, so that contact between the bath solution and the workpiece can be avoided. Usually, 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 used.

Without a barrier layer is an acidic bath such. B. an acidic copper plating or nickel plating a disturbing pickling attack on the clean or cleaned metallic surface based on iron and / or zinc exert, which then always occurs when immersing a less noble metal in the solution of a nobler metal a sedimentation, because then in particular Iron or / and zinc ions are leached out of the object to be coated, go into solution and electrons are released thereby, which in turn are taken up by the ions of the acid plating bath and cause a sedimentation.

The aim of every galvanic (= with current) treatment is to electrolytically apply a cover layer from an acidic aqueous solution to the metallic object, since the acidic electrolyte has significant advantages in terms of deposition rate, gloss, metal distribution, opacity, compared to an alkaline electrolyte. 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 galvanic processes are used only in rare cases, eg. B. if the number of bathrooms z. B. for reasons of space not sufficient for expansion to an acidic galvanic treatment. These baths then work at pH values greater than 10, with several disadvantages to be taken into account, such. As gloss level, sensitivity to impurities and foreign substances, slower deposition and a worse depending on the current density metal distribution and accordingly inferior depth dispersion. However, such an acidic aqueous solution requires a barrier layer on metallic surfaces, especially of iron and zinc materials, so as not to interfere with the acidic aqueous solution to absorb interfering impurities, ions and electrons from the metallic substrate and to affect the electrolytic deposition process and the quality of the galvanic cover layer.

DE 39 14 180 02 discloses compositions of electroless copper sulphate and cyanide based copper baths which operate at a pH of at least 9.5 and which receive the electrons necessary for metal deposition from a reducing agent, mostly 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.

US 3,715,793 discloses off-current 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 at 40 be deposited 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 only adherent and copper-plating with layers suitable for further processing without electricity, if the bath at least one strong reducing agent such. B. hypophosphite and / or pyrophosphite is added and / or if a barrier layer of a cyanide, alkaline electrolytic copper bath, a cyanide-free, alkaline, complexing agent-containing electrolytic copper bath or acidic nickel strike bath was previously deposited.

So far, a workpiece made of zinc materials are not adherent and copper-plating with no further usable for further processing without power or nickel-free acid or alkaline nickel-plated, without the bath at least one strong reducing agent such. As hypophosphite and / or pyrophosphite is added and / or without previously a copper barrier layer of a cyanide alkaline electrolytic bath or a cyanide-free, alkaline, complexing agent-containing electrolytic bath was deposited.

So far, a workpiece made of iron or zinc materials are not adherent and can be alkaline-copper-plated with current usable for further processing without power or nickel-plated without electricity, without the bath at least one strong reducing agent such. B. hypophosphite and / or pyrophosphite is added.

EP 1 495 157 B1 teaches an aqueous, freeze-thawing and thawing concentrate 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.

It was the task of proposing methods for coating, in which cover layers such. B. glossy and / or thick films are applied electrolytically, without prior to forming the electrolytic cover layer (s) a cyanide alkaline bath such. For example, a cadmium, copper plating, nickel plating or galvanizing bath or electroless bath is used to form a barrier layer.

In addition, the object was to propose methods of coating that are as cost-effective, fast, high quality and environmentally friendly. 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 method 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 of treating a metallic surface of an article with an aqueous copper plating solution wherein on clean metallic surfaces of the article or after pretreatment on cleaned metallic surfaces a first copper plating solution which is free from cyanide and which is free from intentional added strong reducing agent having 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. 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. More preferably, the first copper plating solution is cyanide-free and free of strong reducing agent having a potential of 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, with the copper plating according to the invention, with suitable chemical composition of the bath, that is content of at least one alloying element such. As zinc and / or tin, and 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, such as. For example, "nickel" in the baths include both nickel and nickel with alloying elements, and in the layers nickel and nickel alloys.

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.

Optionally, at least one galvanic cover layer z. For example, on the electrolessly applied barrier layer and / or conductive layer. B. based on copper, nickel or one of their alloys electrolytically.

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. 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, triethanolamine , Tetrakis (2-hydroxypropyl) ethylenediamine (THPED), Pentahydroxypropyldiethylentriamin and derivatives thereof, in particular free of ethylenediaminetetraacetate (EDTA) with appropriate environmental, Toxizitäts-, Abwasserbehandlungs- and / or treatment problems held.

The copper plating solution used according to the invention is preferably also 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 and / or one of its derivatives such as a citrate such. For example, sodium citrate, potassium citrate or / and ammonium citrate may be particularly difficult to be coppered metallic surfaces such. As those made of stainless steel be advantageous, especially in a content of the bath in the range of 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 there 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. 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 of the present invention. But the herausgebizizten from the metallic surface and / or dissolved ions such. As Fe ²⁺ , Sn ²⁺ , Zn ²⁺ or / and other ions z. Example of alloying constituents and / or other metallic materials of the treated metallic surface, which often have values in the range of -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 leached from the surfaces and / or leached out.

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. of the iron material is angeizizt, so that herausgebizizt or / and dissolved out z. B. iron ions can act as a reducing agent. Therefore, the invention used electroless copper plating operates at least immediately after the first contact with a base metal or material with ions such. B. 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 pHs in the range of 4 to 8, and more preferably 6.5 to 8, zinc-rich surfaces work well, with zinc going into solution because of the potential difference between zinc and copper, and not because of the pickle 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 needs to 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 potential values in the range of -0.1 to -2.5V or -0.4 to -2V.

In the method according to the invention, the barrier layer and / or conductive layer produced according to the invention can also be based on iron and zinc materials including stainless steel and tin in a simple, cost-effective, environmentally friendly and faster manner than according to prior art methods be applied. Preferably, this method has no complicated additional process steps such. As a necessary electropolishing or a necessary electrolytic degreasing.

• 1. Ein alkalisches oder pH-neutrales Heißentfetten, um z. B. Reste von Fett, Öl, Staub usw. zu entfernen, und danach Spülen mit Wasser.
• 2. Ein Aktivieren der insbesondere oxidisch verunreinigten metallischen Oberfläche z. B. durch saures oder selten auch alkalisches Beizen oder/und durch mechanische Bearbeitung wie z. B. Läppen, Schleifen, Strahlen sowie durch anschließendes Spülen mit Wasser. Im Falle des alkalischen Beizens oder beim Weglassen jeder Art eines solchen Aktivierungsschritts ist ein Dekapieren mit einer stark verdünnten, leicht sauren wässerigen Flüssigkeit üblich.

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

• 1. An alkaline or pH-neutral hot degreasing to z. B. remove residues of grease, oil, dust, etc., and then rinse with water.
• 2. Activation of the particular oxidically contaminated metallic surface z. B. 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 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. B. 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 11 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 / and strong complexing agent, wetting agent, buffer substance, a weak reducing agent, acid, pH adjusting agent or / and optionally have further additives. It preferably contains ions and in particular herausgeizizizte and / or dissolved out ions such. B. Fe ²⁺ , Zn ²⁺ or / and other ions, the z. Example of alloying constituents and / or other metallic materials of the treated metallic surface or leached / / were dissolved and the values of the potential in the range of -0.4 to -1.8 V have. 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 additive z. Fe ²⁺ , Sn ²⁺ and Zn ²⁺ , so that upon immersion of the object to be treated of base metallic material in the usually acidic or neutral copper plating solution ions are automatically released, 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 here as a native reducing agent.

The copper plating solution according to the invention may contain acids such as sulfuric acid, hydrochloric acid, nitric acid and / or hydrofluoric acid as mordant, in particular in amounts ranging from 0.1 to 200 g / L, more preferably from 5 to 130 g / L or from 50 to 80 g / L. Preferably, the total acid content ranges from 0.1 to 400 g / L or from 10 to 200 g / L or from 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. When pickling is often in acidic solutions, preferably at least one alkali halide such. For example, sodium chloride or / and sodium fluoride used.

Complexing agents such. As citric acid and its derivatives and chemically related carboxylic acids and their derivatives are considered in the electroplating as a weak complexing agent. 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 amount of wastewater treatment required. The copper plating solution according to the invention is preferably free of strong complexing agents such. B. free of cyanides, amines, carboxylic acids and their derivatives, since they cause a corresponding environmental, toxicity, Abwasserbehandlungs- and / or treatment problems. They are preferably not intentionally added in many embodiments. Examples of such complexing agents are, for. As gluconic acid, lactic acid, tartaric acid and derivatives thereof such. Sodium gluconate, Rochelle salts, ethylenediamine, diethylenetriamine, diethanolglyoxime, 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.

But a subsequent electrolytic topcoat need not be prepared with an electrolyte that is free of strong chelating agents, regardless of their composition and content, eg. B. of 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 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, for example, at least one compound based on alkyl sulfonic acids, of amines such as. B. reaction products with propylamines, of benzenesulfonic acids, of coumarins, of esters of (meth) acrylic acids, of melilotic acid, of saccharines, of sulfonamines, of sulfonimides or / and of sulfinic acids are added / be.

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, bristles, ammonium compounds and / or derivatives thereof can be used as buffer substances in the copper plating solution according to the invention. 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, particularly preferably in the range from 0.1 to 20 g / l or from 0.5 to 5 g / l.

As an adjusting agent, for example, acids and bases or / and derivatives thereof 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 intentionally added strong reducing agent, d. H. free of reducing agent, which has values of the potential 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. As organic stabilizers z. As diethylenetriaminepentaacetic acid, phosphonic acid, thioglycolic acid, thiourea or / and derivatives thereof. As inorganic stabilizers z. B. compounds based on cadmium, lead, vanadium or / and mercury can be used. Usually, such stabilizers are poorly biodegradable. Because the organic stabilizers can solve the heavy metals from sediments and possibly cause their transport into water, while 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 as possible of toxic heavy metal ions.

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 of the copper plating solution according to the invention, a pickling attack on a ferrous material such. B. 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 coppering of metals that are less noble than z. As iron, and for their alloys, the pH of the copper plating solution is often preferably in a range of about 4 to 8 or from 5 to 8. For the copper plating of zinc or zinc-containing alloys, the pH of the copper plating solution is particularly preferred 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 6 to 8 or for iron-rich metallic surfaces less than 5.

The electroless copper plating according to the invention and / or a subsequent electrolytic coating can be effected by dipping, spraying, rolling, brushing, casting, by sponge application, by padding or / and in a similar manner. Usually work is done in diving. It is preferred to electrolessly coat by dipping, spraying, rolling on, brushing on, casting on, by sponge application or / and by padding application and / or thereafter. 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 attention is paid to the concentration of copper solution and / or sufficient treatment time.

Preferably, electroless copper plating 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 to form a copper layer according to the invention as a barrier layer and / or as a conductive layer. If the bath is a lower concentration than z. B. has 0.5 g / L copper in the copper plating solution, then pay attention to a higher bath temperature and / or longer treatment time. If the Verkupferungsbad a higher concentration than z. B. has 100 g / L Cu in the copper plating solution, then lower bath temperature, lower treatment time, higher levels of Beizinhibitor and / or higher levels of brighteners to pay attention. However, if the copper concentration in the bath, the bath temperature, the treatment time, the level of pickle inhibitor or / and the level of brightener in the copper plating solution are not matched, then either porous copper layers or spongy, poorly adherent copper layers can be formed. In the inventive electroless copper plating preferably forms a copper layer thickness in the range z. B. from 0.1 to 8 microns or in the range of 1 to 5 microns, in particular within 0.5 to 2 minutes.

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. Because the time saved in the electroless deposition is about 20 to 90% compared to the electrolytic or electroless deposition. 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, this results in a better corrosion protection and / or a better electrical conductivity than the base material itself has.

On the at least one inventively electroless copper layer can be further electrolytically coppered if necessary and / or further electrolytically nickel-plated, z. B. to apply 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. Then, if necessary, in each case additionally at least one electrolytic silver, chromium, gold, cadmium, platinum or / and rhodium layer can be applied in particular from acidic, cyanide-free and reducing agent-free electrolytes, eg. B. as at least one gloss and / or at least one thick film.

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. The joining can z. B. by gluing, clinching and / or rolling together 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. ZnAlMg- and ZnAlMgCu alloys (ZAMAK alloys) well electroless copper according to the invention.

A sputtering could not be achieved isolated in very inhomogeneous or superficially heavily contaminated zinc alloys, z. Example, if aluminum halos in the alloy deposition due to the potential difference between z. B. Al 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 of stainless steel surfaces according to the invention 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 electroless copper plating optionally in addition an electric conductive contact of a less noble metal than stainless steel such as aluminum, aluminum alloy, low-alloyed iron and steel materials, zinc or / and zinc alloy to stainless steel surface z. B. was used via a contact wire, could be successfully copper in several attempts. In the process according to the invention, stainless steel surfaces are electroless copper-plating by using at least one nonoxidizing acid for previous activation before pickling and by additionally using an electrically conductive contact of a less noble metal as stainless steel to the stainless steel surface for coppering. 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 on the current level of knowledge in the stainless steel surfaces as necessary, the higher content of steel refiners such. B. Cr, Ni or / and V included. 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 an electrically conductive contact of a sacrificial metal z. 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. For low-alloy stainless steels, the so-called sedimentation in the dipping process already works when it is applied in the dipping process. The copper plating quality does not suffer from this. The bath contents and the thermal conditions for copper plating of stainless steel surfaces are almost the same during the contact and dipping process as well as during the dipping process as in the copper plating of steel surfaces.

Furthermore, it has now been found that also tin surfaces can be coppered 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 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 die-cast zinc in an environmentally friendly manner can be applied. 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 in the electroplating in the decorative or / and functional coating of workpieces z. Example of iron, steel, zinc, zinc die-casting or tin on an electrolytic pre-copper plating or electrolytic nickel plating to form a barrier layer and replace it with an electroless plating process in an acidic bath.

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. It was surprising that it is then possible to apply an acidic electroplated coating on surfaces of iron- or / and zinc-rich metallic objects or on tin - because until today, surface coaters learn that a layer deposited on an object with a Surface based on iron and / or zinc from an acidic copper electrolyte, is not suitable for further processing.

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 has also been 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.

Moreover, 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 luster coppering or subsequent acid luster nickel plating can be dispensed with and If required and depending on the application, then directly galvanically nickel plated, galvanized, gold plated, galvanized, and / or 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 bright copper layer. This is independent of whether it was carried out without current with a cyanide-containing copper plating solution or with a copper plating solution used according to the invention. It is also independent of whether the barrier layer while on a surface z. B. from a ferrous material, a zinc material, a tin material and / or was applied to a nobler surface.

The coated with a conductive layer according to the invention coated article can be used to produce a more electrically conductive object such. As a wire, profile, pipe, rod or intricately shaped object can be used for conductive heating and / or curing of the metallic article

The object coated with a barrier layer and / or conductive layer according to the invention can be used as a wire, profile, pipe or rod, as a welding wire, as a fitting, element or connecting element z. B. for windows, doors or furniture such. As a role or a screw, as an element of an apparatus, a machine, a household appliance, an electrical appliance, an electronics article or toys such. B. as a switch or button, as a decorative item such. B. as a candle holder, as an element for a clock, as a housing, linkage, bracket, mounting plate or panel, as an element in the apparatus, engineering, automotive or transportation, as a mechanical part or for a metallic object to be cured such. As a drill, a subject subject to wear, especially in apparatus, in vehicle, in engineering or tooling 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. The trapezoidal layout of the Hull cell varies the distance between the anode and the 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 use an electrolyte such. For example, to test an acidic high gloss copper bath on a single Hull cell sheet over a wide current density range important to metal deposition.

The adhesion of the applied layers was detected by crosshatching, wiping and bending tests DIN EN ISO 2409 , to DIN EN ISO 1519 and after ASTM 2794 checked and confirmed with these tests in all examples of the invention as well adherent.

Inventive Example 1 to electroless copper barrier layer:

Two commercially available ST2 steel sheath plates were degreased alkaline hot in 10 g / L NaOH, 30 g / L sodium pyrophosphate and 5 g / L wetting agent at 70 ° C. for 3 minutes, thoroughly rinsed with city water, and decanted for 10 seconds in 5% sulfuric acid ( = briefly stained 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 diluted with city water solution of Gardobond ^® 7602 CU of Chemetall GmbH comprises an aqueous composition based on basic copper carbonate, weakly basic buffer substance, a weak complexing agent and a brightener. The prepared with sulfuric acid The copper plating solution according to the invention 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 microns 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 Hullzellenbleches over 180 ° was possible without Schichtabplatzungen 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. The 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 of the conventional production process could have been omitted.

The sheets also exhibited under varied pretreatment conditions and under varied conditions for forming the barrier layer, such as temperature, concentration and immersion time on the basis of Gardobond ^® CU 7602 smooth, glossy, and over the entire current density range from 0.1 to 20 A / dm ² in an acid , 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 to continue to be electrolytically copper-plated, electrolytically nickel-plated or otherwise electrolytically deposited or / and electrolessly deposited by chemical means to form colored 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 treatment was carried out in
100 g / L Gardobond ^® CU 7600 Chemetall GmbH and
150 g / LH ₂ SO ₄ of technically pure quality.

Gardobond ^® CU 7600 is sold by Chemetall GmbH in powder form. Gardobond ^® CU 7600 aqueous solution contains copper sulphate 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 would also have a direct Instead of the bright copper plating, it would be possible to follow the process of bright nickel plating, so that both the cyanide copper plating and the acid copper plating could have been omitted.

The sheets showed smooth under varied pretreatment conditions and varied conditions for electroless formation of the barrier layer using Gardobond ^® Cu 7600 as concentrations, temperatures and immersion times, high gloss and very good adhesion over the entire current density range copper barrier layers. The thickness of the applied barrier layer was 1.6-1.7 microns 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 GT0. A bending of Hullzellenbleches 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.

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 to continue to be electrolytically copper-plated, electrolytically nickel-plated or otherwise electrolytically deposited or / and electrolessly deposited by chemical means to form colored 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.

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 the 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 the hot degreasing and rinsing with water and cathodically degreased to readjust the conventional process used in the 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. As a result, about five times the time was required for the formation of the galvanically produced barrier layer for a certain layer thickness as in the inventive electroless copper plating of the barrier layer.

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 1.2-2.5 μm on the side facing the anode, depending on the anode distance extension prevailing in the Hull cell. The copper barrier layers could not be scraped off with a fingernail. The crosshatch adhesion test was passed with GT0. A bending of Hullzellenbleches over 180 ° was possible without Schichtabplatzungen at Biegeinnen- 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 hardly or not be reached by the field lines of the current, depending on the prevailing in the Hull cell anode distance extension and throwing power of the cyanide, galvanic copper plating bath 0.06 and 1.4 microns, took but towards the outer edges of the sheet too. In the middle of the sheet was on the back of an area of about 2.3 × 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 on the influence of the part spectrum:

In order to test the performance of the barrier coatings achieved with Chemetall GmbH Gardobond ^® CU 7600 and Gardobond ^® CU 7602 pretreatment products, in order to cope with the range of parts to be treated in a batch electroplating shop and, above all, to cope with the spectrum of treated alloys Handling various sections of various vending machine, construction, and spring steel alloy samples for the purpose of enhancing corrosion protection and / or optical finishing according to the methods of Examples 1 and 2 and treated by the methods of Comparative Examples 3, 4 and 4a, respectively.

In the treatment according to the invention of the various parts according to the processes of Examples 1 and 2, the same high-quality properties and advantages were obtained in all parts as in Examples 1 and 2.

In this case, the parts after galvanic treatment in bright copper electrolyte or thick copper electrolyte had well-adhering and well-formed high-gloss glossy copper layers or high-gloss thick copper layers. In the interior of the pipe, where galvanic plating 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 plating 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 cage inside with electricity, in addition, showed a very rough, granular and gritty non-stick copper layer. This partly dissolved already during the electroplating process in the electrolyte and polluted it accordingly.

In 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 depending on the part depth or geometry or length of the pipe section. At the sites not accessible by current, 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 acidic 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 plating baths such. B. a high gloss nickel bath could have 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 GTO. A bending of the test sections over 180 °, also as far as it was possible by the part geometry, was possible without Schichtabplatzungen on Biegeinnen- and Biegeaußenkante. The applied barrier layer according to Examples 1 and 2, regardless of the part geometry, a layer thickness, depending on the base material, between 1.1 and 1.6 microns, with 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 .mu.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 .mu.m was deposited at locations which were well supplied with electrolytic material, with the copper-plating being distributed unevenly, depending on the anode spacing and, correspondingly, increasing current density, on the workpieces. In addition, the barrier layers coated according to Examples 4 and 4a were ductile, almost nonporous, crystalline, and exhibited slight internal tensile layer stresses.

Comparative Example 6 for Conventional Screw Production:

High-quality 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 good electrically conductive copper layer as a conductive layer, which should have a layer thickness in the range of 1 to 5 microns.

• 1. Heiß/Abkochentfetten in 10 g/L NaOH, 30 g/L Natriumpyrophosphat und 5 g/L Netzmittel bei 70°C über 3 Minuten,
• 2. Spülen in VE-Wasser,
• 3. Beizen in HCl von ca. 15%, bei Raumtemperatur über 3 Minuten,
• 4. Spülen in VE-Wasser,
• 5. Elektrolytisches Entfetten in 10 g/L KOH, 30 g/L Natriumsilicat, 10 g/L Pyrophosphat und 1 g/L Netzmittel bei 2 A/dm² und 30°C über 3 Minuten zur kathodischen Reinigung,
• 6. Spülen in VE-Wasser,
• 7. Dekapieren in 3%iger HNO₃ bei Raumtemperatur über 10 Sekunden,
• 8. Spülen in VE-Wasser und
• 9. Cyanidisches alkalisches elektrolytisches Verkupfern mit wässeriger Lösung auf Basis von ca. 15 g/L Cu, ca. 50 g/L Natriumcyanid, ca. 50 g/L Natronlauge, Netzmittel, Glanzbildner und weiteren Additiven bei 1 A/dm² und 50°C über 10 Minuten, wobei eine Schichtdicke von 3–5 μm erzielt wurde.

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 fats 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% HNO ₃ at room temperature for 10 seconds,
• 8. Rinse in demineralised water and
• 9. Cyanidic 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 solution, wetting agent, brightener and other additives at 1 A / dm ² and 50 ° C for 10 minutes, with a layer thickness of 3-5 microns 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 the test screws over 90 °, as far as it was possible by the part geometry, was possible without Schichtabplatzungen on Biegeinnen- and Biegeaußenkante. 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 μm thickness. 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 screw production:

Quality screws were treated as in Example 7, but with the difference that the electroless dip Gardobond CU ^® 7600 was used 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 luster, from 1.3 to 1.5 μm 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 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, very simple, inexpensive, without much energy and effortless. The conductive layer could be applied in a particularly safe, non-toxic and environmentally friendly manner compared to prior art methods. The copper layer, in contrast to the prior art cyanide electrolytic copper layers, is non-porous and therefore of higher quality and more 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, but the cyanide alkaline electrolytic copper plating step was performed by a cyanide-free and reducing agent-free acidic electrolytic bright copper plating step based on about 200 g / L CuSO ₄ .5H ₂ O and about 60 g / LH ₂ SO 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 microns / 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:

• 1. Entfetten in 10 g/L NaOH, 30 g/L Natriumpyrophosphat und 5 g/L Netzmittel bei 70°C über 3 Minuten,
• 2. Spülen in VE-Wasser,
• 3. Spülen in VE-Wasser,
• 4. Elektrolytisch Vernickelung durch Anschlag-Nickel-Strike mit 200–250 g/L NiCl₂ und 200 g/L HCl bei 2 A/dm² und 30°C über 40 Minuten, für eine Schichtdicke von 30 bis 40 μm, von innen nach außen zunehmend
• 5. Spülen in VE-Wasser,
• 6. Spülen in VE-Wasser,
• 7. Elektrolytisches saures Dickverkupfern als 350 μm dicke Gravurauflage bei 5 A/dm² und 30°C über 240 Minuten.

A steel roller was treated as follows:

• 1. degrease 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 NiCl 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 microns, from the inside increasingly outward
• 5. rinse in demineralised water,
• 6. rinse in demineralised water,
• 7. Electrolytic acidic thick copper plating as 350 μm 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.

Example 11 According to the Invention for the Coppering of Pressure Rollers:

A roller was treated as in Example 10, but the Anschlagvernickelungsprozess 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 was 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 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 microns. 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 11 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 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.

To recheck the adhesion of the coating to the base material, the pressure roll was then turned off a trial 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 microns, 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 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 from 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 recheck the coating adhesion to the base material, this 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.

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

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

Since a barrier layer was missing, when immersed in the acidic thick copper electrolytes an 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:

• 1. Mild alkalisches Entfetten in 10 g/L Na₂CO₃, 5 g/L Natriumpyrophosphat und 5 g/L Netzmittel bei 70°C über 3 Minuten,
• 2. Spülen in Stadtwasser,
• 3. Dekapieren in 5%iger HF bei Raumtemperatur über 10 Sekunden,
• 4. Spülen in Stadtwasser,
• 5. Stromloses neutrales Verkupfern in 200 g/L Gardobond^® CU 7602 ohne Schwefelsäure, aber mit 10-fach erhöhter Menge an Glanzbildner, bei pH-Werten im Bereich von 6,5 bis 7 und 30°C über 30 Sekunden,
• 6. Spülen in Stadtwasser,
• 7. Saures Glanzverkupfern bei 2 A/dm² und 35°C über 15 Minuten.

Various Zinkdruckgußteile such. As push buttons, buttons, switches, window fittings and model articles made of different zinc alloys such as ZL0400, ZL0410 or ZL0430 were subjected to the treatment described below to readjust the part and especially the alloying spectrum of a Lohngalvanikbetriebes:

• 1. Mildly alkaline degreasing in 10 g / L Na ₂ CO 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 between 0.3 and 0.4 μm, regardless of the part geometry, whereby the copper plating spread evenly 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 a 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 Zinkdruckgußteile were plated in a conventional acidic high-gloss copper bath at 2 A / dm ² at a temperature of 35 ° C for 15 minutes galvanically bright. 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 a 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 cyanide copper plating of zinc die castings:

Similar die-cast zinc parts were coated as in Example 14, but the electroless dip treatment was replaced by a conventional alkaline cyanide copper plating process at 1 A / dm ² and 55 ° C for 5 minutes to simulate 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 spread unevenly over the workpiece surfaces depending on the anode distance and correspondingly increasing current density. Due to the Faraday 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 castings coated with a copper barrier layer exhibited high adhesion, but after cyanidic copper plating, a dull surface without gloss because no glossy copper layer had yet been 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 on Biegeinnen- and Biegeaußenkante.

Subsequently, the Zinkdruckgußteile were plated in a conventional acidic high-gloss copper bath at 2 A / dm ² at a temperature of 35 ° C for 15 minutes galvanically bright. 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 destruction of the acid polished copper bath. The zinc die castings 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 cheaper city water high-gloss flawless bright copper layers could be deposited with excellent adhesion as well.

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

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

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

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 a cyanide electrolytic copper plating according to the prior art was used instead (Comparative Example 17), this environmentally friendly toxic process was a good copper plating with increased effort to achieve adherent matte and easily processed copper layers.

The adhesion of the applied layers was detected by crosshatching, wiping and bending tests DIN EN ISO 2409 , to DIN EN ISO 1519 or after 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.

Inventive Example 18 to different composite copper plating baths

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

Table 1: Variation of the bath composition and bath conditions, in each case the total amount z. B. copper, sulfuric acid, brightener or Beizinhibitor be given

• GB ^® stands for Gardobond ^® of Chemetall GmbH.

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. The pH value could be varied in the coating of ferrous materials between 0.1 and 1 without negative influences, while it could be varied in zinc-rich materials between 6.5 and 7.0 without negative influences. 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 detected by crosshatching, wiping and bending tests DIN EN ISO 2409 , to DIN EN ISO 1519 or after ASTM 2794 checked. 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

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 2026698 A1 [0036, 0037, 0039]
• DE 391418002 [0045]
• DE 1521200 A1 [0046]
• US 3715793 [0047]
• EP 1495157 B1 [0052]

Cited non-patent literature

• N. Kanani: Copper Coatings: Deposition, Properties, Applications, Eugen-G.-Leuze-Verlag Bad Saulgau 2000, p. 73/74 [0041]
• DIN EN ISO 2409 [0109]
• DIN EN ISO 1519 [0109]
• ASTM 2794 [0109]
• DIN EN ISO 2409 [0178]
• DIN EN ISO 1519 [0178]
• ASTM 2794 [0178]
• DIN EN ISO 2409 [0181]
• DIN EN ISO 1519 [0181]
• ASTM 2794 [0181]

Claims (19)

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 which is free from intentionally added strong 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. A method according to claim 1, characterized in that an article is treated from a ferrous material, zinc, a zinc alloy and / or a tin material. A method according to claim 1 or 2, characterized in that stainless steel surfaces are copper-plated, wherein for pickling before coppering at least one non-oxidizing acid is used for the previous activation and wherein for coppering, if necessary, additionally using an electrically conductive contact with a less precious metal as stainless steel becomes. Method according to 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. Method according to one of the preceding claims, characterized in that a first copper plating solution is used cyanide-free electroless for the formation of a barrier layer and / or a conductive layer on a less noble metallic surface than copper. Method according to one of the preceding claims, characterized in that the first copper plating solution contains no intentionally added reducing agent and no strong and optionally also no weak complexing agent with the exception of ions leached out of the surfaces and / or leached out. Method according to one of the preceding claims, characterized in that the first coppering solution contains no intentionally added complexing agent or no complexing agent. A method according to claim 6, characterized in that the first copper plating solution contains ions having potential values in the range of -0.4 to -1.8 volts. 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 contains at least one copper compound and at least one brightener, at least one acid or / and at least one pickling agent. 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 pickling inhibitor and optionally also a pickling amplifier. 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. A 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 is in the range of 4 to 8.5 or for iron-rich metallic surfaces is less than 5. Method according to one of the preceding claims, characterized in that after the formation of the barrier layer and / or conductive layer at least one cover layer is applied as a glossy layer electrolytically or at least one layer as a thick layer chemically or electrolytically. Method according to one of the preceding claims, characterized in that is electrolessly coated by dipping, spraying, rolling, brushing, casting, by sponge application and / or by tampon application and / or thereafter. Method according to one of the preceding claims, characterized in that the object provided with a barrier layer undergoes at least one subsequent surface treatment. A method according to claim 13, characterized in that the object provided with an electroless copper layer is at least once treated electroplated, at least once painted or coated with a powder coating or with a cathodic dip (KTL) or is joined together with another object. An article having a barrier layer and / or a conductive layer made according to any one of claims 1 to 16. Use of a barrier layered and / or conductive layered article made according to any one of claims 1 to 16, as a wire, profile, pipe or rod, welding wire, fitting, element or connecting element, element of an apparatus, a machine, a machine 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 panel, as an element in apparatus construction, engineering, automotive or transport, as a mechanical part or for a to be hardened metallic object or as a screw. 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.