EP3084043B1 - Method for electrolytic surface modification of flat metal workpieces in copper-sulfate treatment liquid containing sulfate-metallates - Google Patents

Description

The present invention relates to a method for the electrolytic surface modification of a sheet metal workpiece by deposition of copper aggregates. The invention further relates to the flat metal workpieces produced by this method and the use of the metal workpieces as a substrate for the formation of solid adhesive bonds with a variety of materials.

As a condition of a binder-free pressing of surfaces of different materials, the generation of a large and rough surface is considered. Depending on the material combination, the surfaces are first cleaned and then structured. The structuring takes place in metal-metal composites by dry brushing or grinding. In metal-plastic composites, which are generally produced by extruding a plastic onto a metal surface, the metal surface is e.g. by conversion, such as phosphating, chromating, etc. pretreated, or the metal surface is modified by deposition of a highly in-depth ("rough") surface of a metal (treatment). In addition to these developments, especially bioadapted developments in plastics are of interest, leading to surfaces occupied by microdimensional adhesion islands (e.g., suction cups).

In electrically particularly sensitive and chemically extremely demanding composite systems, the use of as few components as possible in the bonding zone is advantageous because the release of interfering substances is less likely here and because the failure of the composite can be limited to a minimum.

For this reason, in the abovementioned fields of application, the composites are preferably produced from a brushed or treatment-modified metal surface and the desired material to be rolled on, to be pressed or wound up.

The production of flat endless material (tapes, films) with such a treatment is usually carried out according to the classical processes of strip electroplating. The technical difficulties of the processes used here - degreasing, electrolytic cleaning, pickling, coating - consist in the insufficient even stocking of the surface of films and tapes. The achievable "ordinary" cleanliness of the surface and the locally different roughness of the material allow only a locally preferred growth of aggregates of the treatment on the surface.

A known method for the surface treatment of a metal workpiece, such as a metal strip or a sheet, is the electrolytic coating of a metal surface with a metal or a metal alloy. For example, in the electrolytic strip coating, the strip is passed through one or more electrolytic cells. In each electrolytic cell, the band is usually brought via so-called power rollers in a fixed-solid connection to the negative pole of a rectifier. The band thus serves as a negative electrode, i. as a cathode. The positive electrode, i. the anode, is usually formed as a pair of electrodes, wherein the band passes between the two electrodes.

Due to the electrolytic coating, the metal workpiece to be coated is uniformly provided on all sides with a substantially flat metal coating. Even with the use of metal workpieces with a relatively rough surface finish, the surface is leveled. However, for applications where good adhesion to another material is required, a smooth surface may be undesirable. Good adhesion between two materials is achieved when there is a chemical interaction and / or mechanical interlocking in topographical features of the adhesion partners. If this is not or not sufficiently the case, the adhesion deteriorates. Thus, poor adhesion between a metal surface and the same or another material, such as a lacquer layer, a paint layer or an adhesive, can result in poor quality or even unusable products.
To improve the adhesion to metal surfaces, various technical solutions have been developed. As an electrolytic process for improving adhesion to metal surfaces, anodization is known. In anodizing, using an acidic electrolyte such as sulfuric, phosphoric or chromic acid on the surface of a metal workpiece connected as an anode becomes regular structured, porous oxide layer formed. The pores allow the anodized metal workpiece to mechanically interlock with another material, such as a paint, varnish or adhesive layer. However, anodizing is limited to a few metallic materials such as aluminum, titanium and alloys thereof. Above all, the anodizing of aluminum (anodizing process, electrolytic oxidation of aluminum) is of industrial importance. Here, an aluminum oxide layer having a porous structure is formed on the surface of the aluminum material.

An improvement in adhesion can also be achieved by preceding a step of electrolytic pretreatment of the surface to be coated. For example, prior to the actual cathodic deposition process, the metal workpiece may be subjected to an anodic treatment in which an ablation process is induced in which minute particles and contaminants on the surface of the metal foil are removed and a bare surface is obtained. In the subsequent cathodic treatment, a deposition / coating process is induced in which a metal from the treatment liquid at the cleaned and bare surface is usually deposited in the form of aggregates. The anodic and cathodic polarization can be carried out similarly to the classical galvanic coating by solid-solid contact or, in an advanced process management according to the central conductor principle, be a non-contact polarization.

In all the surface modification methods mentioned above, the columnar form of the deposited aggregates limits the adhesion in the composite. Bonding in the composite improves with the number of aggregates per unit area. It always strives for a limit, which consists in the resistance to breakage / breakage of the aggregates themselves. For example, due to the length of the aggregates of the adhesive bond is significantly dependent on the flow behavior aufzupressender plastics, especially if the flow behavior is so poor that the plastic does not reach the bottom of the treatment and only undercuts at the tips of the aggregates arise. The composite is then comparable to a plastic plateau on metal posts. Even if such an adhesive bond is sufficiently good, at the base of the classic aggregates of the treatment in the composite remain cavities into which aggressive chemicals can penetrate and corrosively damage or destroy the adhesive bond.

US 5 015 340 A discloses a process for the electrolytic coating of metal wires using a nickel bath.

DE 199 51 325 A1 describes the electrolytic treatment of film material in a treatment liquid.

EP 0 838 542 A1 deals with a process for the electrolytic pickling of stainless steel strips.

US 4 097 342 A discloses the electroplating of aluminum workpieces with zinc or tin containing baths.

CN 101 892 502 A and US Pat. No. 3,666,636 A describe electrolytic treatment liquids containing, inter alia sulfuric acid copper sulfate and lanthanum chloride or cerium oxide.

There is therefore a need for a method for improving the adhesion or adhesion to metal surfaces. It is therefore an object of the present invention to provide a simple and efficient method for increasing the adhesion of flat metal workpieces. Another object of the invention is to provide a method of modifying / converting the surface of a sheet metal workpiece by depositing a rare earth doped copper layer.

Brief description of the invention

• wenigstens eine Oberfläche des flächigen Metallwerkstücks in einer Behandlungsflüssigkeit anodisch gepolt wird und dadurch ein anodischer Auflösungsprozess induziert wird, und dann
• die wenigstens eine Oberfläche des flächigen Metallwerkstücks in der Behandlungsflüssigkeit kathodisch gepolt wird und dadurch ein kathodischer Abscheidungsprozess zur Abscheidung eines oder mehrerer Metalle auf der wenigstens einen Oberfläche des flächigen Metallwerkstücks induziert wird,
• dadurch gekennzeichnet, dass als Behandlungsflüssigkeit (Elektrolyt) eine leitende Flüssigkeit auf der Basis von Schwefelsäure/Sulfat-Lösungen des Kupfers verwendet wird und die Behandlungsflüssigkeit ferner ein oder mehrere Elemente, ausgewählt aus der Gruppe bestehend aus: Yttrium, Lanthan und Lanthanoiden, enthält. Das Verhältnis zwischen (i) der Summe der Stoffmengenanteile (in mol/l) von Yttrium, Lanthan und/oder der Lanthanoide und (ii) den Stoffmengenanteilen (im mol/l) von Kupfer beträgt 0,0182 oder mehr, vorzugsweise 0,0182 bis 0,127.

To achieve this object, a method for the electrolytic surface modification of a flat metal workpiece is provided according to the invention, in which

• at least one surface of the sheet metal workpiece is anodically poled in a treatment liquid, thereby inducing an anodic dissolution process, and then
• the at least one surface of the sheet metal workpiece is cathodically poled in the treatment liquid, thereby inducing a cathodic deposition process for depositing one or more metals on the at least one surface of the sheet metal workpiece,
• characterized in that a conductive liquid based on sulfuric acid / sulfate solutions of the copper is used as the treatment liquid (electrolyte) and the treatment liquid further contains one or more elements selected from the group consisting of: yttrium, lanthanum and lanthanides. The ratio between (i) the sum of the mole fractions (in mol / l) of yttrium, lanthanum and / or the lanthanoids and (ii) the mole fractions (in mol / l) of copper is 0.0182 or more, preferably 0.0182 to 0.127.

The method of the invention provides a simple and efficient method of increasing the adhesion of sheet metal workpieces.

Detailed description of the invention

The present invention provides a method of surface electrolytic modification of a sheet metal workpiece, wherein at least one surface of the sheet metal workpiece is anodized in a treatment liquid is poled and thereby anodic dissolution process is induced, and then the at least one surface of the sheet metal workpiece in the treatment liquid is cathodically poled and thereby a cathodic deposition process for depositing one or more metals on the at least one surface of the sheet metal workpiece is induced.

The treatment liquids used in the process according to the invention are conductive liquids based on sulfuric acid / sulfate solutions of copper. Their preparation succeeds simply by the dissolution of suitable salts or oxides of copper in aqueous sulfuric acid. The amount of sulfuric acid used is preferably chosen so that after dissolution remains a residual concentration of free sulfuric acid. Preferably, this residual concentration of free sulfuric acid is at least 0.664 mol / l.

The molar ratio (i.e., the ratio of mole fractions) between copper ions and free sulfuric acid is preferably in the range of 1.05 and 1.25, more preferably 1.10 to 1.20, more preferably in the range of 1.15 to 1.17. In a specific embodiment, the ratio is about 1.16. As copper source is u.a. Cupric sulfate pentahydrate, cupric oxide, copper (II) carbonate or basic cupric carbonate.

The treatment liquid is further added one or more conductive salts. Suitable conductive salts in the present invention are rare earth salts (SE) yttrium, lanthanum and lanthanides (Ln), which in the acidic treatment liquid form readily soluble sulfatometallates of the general formula Cu ₃ [SE (SO ₄ ) ₃ ] ₂ ( SE = rare earths). The sources of yttrium, lanthanum and lanthanides include the element (III) oxides and the elemental (III) carbonates. Lanthanum oxide is particularly preferred. The yttrium, lanthanum or lanthanoide salts are added to the treatment liquid in an amount such that the molar ratio between (i) the sum of the mole fractions of Y, La and / or Ln and (ii) the mole fractions of copper is 0.0182 or more, preferably 0.0182 to 0.127. The concentration of the sum of the yttrium, lanthanum or lanthanoid ions is preferably 0.014 mol / l or more, preferably in the range of 0.014 mol / l to 0.35 mol / l and in particular in the range of 0.024 to 0.098 mol / l.

Especially at high ratios between yttrium, lanthanum and / or lanthanides and copper (≥ 0.024), the sequence of the solution of the components for the rapid preparation of the electrolyte is crucial: first, the presentation of the aqueous sulfuric acid, then the dissolution of the copper (II) - connection and possibly the separation of insoluble constituents in the use of oxides / carbonates of copper. Subsequently, the solution of the used compound (s) of Y, La and / or Ln takes place. The addition of the carbonates and the lanthanum oxides / lanthanide oxides must always be carried out with good stirring and partial proportions appropriate to the batch amount, in order to overfill or squirt the resulting electrolyte solution by the released carbon dioxide or local overheating [La (III) and Ln (III) oxides react strongly exothermic with acids.

Examples of suitable copper sulfate-based acidic treatment liquids (electrolytes) are shown in Table 1 below. <b> Table 1. </ b> Aqueous sulfuric acid copper SE electrolytes prepared from the corresponding oxides of the lead ions (LaO, YO, NdO, GdO and DyO, respectively). electrolyte name Leition Conc. Cu ions in mol / l Conc. Free sulfuric acid in mol / l Conc., Lead ions in mol / l Counterion for Cu and lead ions Electrolyte 1 La 0.77 0.664 0.0245 sulfate Electrolyte 2 La 0.77 0.664 0.0490 sulfate Electrolyte 3 La 0.77 0.664 0.098 sulfate Electrolyte 4 Y 0.77 0.664 0.0245 sulfate Electrolyte 5 Nd 0.77 0.664 0.0245 sulfate Electrolyte 6 Gd 0.77 0.664 0.0245 sulfate Electrolyte 7 Dy 0.77 0.664 0.0245 sulfate

The addition of yttrium, lanthanum and / or lanthanide ions to the treatment liquid in the method according to the invention for surface modification means that the typical stalked aggregates (also referred to below as "dendrites") do not appear on the surface of the flat metal workpiece to be modified Separate balls occupied with standing slats. The adhesive bond (adhesive force per unit area) of these units over, for example, plastic increases depending on the specific circumstances to twice or nearly three times the bond of the classic treatment produced.

As an additional effect in the deposition from the acidic copper (II) S-sulfate treatment liquids, incorporation of the rare earths (Y, La and / or Ln) added as conducting salts into the copper layer was found. While the diamagnetic SE (III) ions of yttrium and lanthanum are incorporated only loosely bound, for example, the paramagnetic Ln (III) ions of neodymium, gadolinium or dysprosium deposit at the same concentration in the treatment liquid firmly anchored in the copper layer. This is shown in Table 2. <b> Table 2. </ b> Installation of rare earths (SE) from acid copper (II) S sulfate treatment liquids into the copper layer deposited on the surface of the sheet metal workpiece SE (III) ion Conc. In the treatment liquid (mol / l) Effective magnetic moment SE (III) (μb) Molar ratio in the layer n (SE) / n (Cu) yttrium 0.0246 0 0.0036 lanthanum 0.0246 0 0.0006 lanthanum 0.0492 0 0.0013 neodymium 0.0246 3.6 0.0058 gadolinium 0.0246 7.8 0.0024 dysprosium 0.0246 10.8 0.0021

The structuring of the deposited layer and the incorporation of the SE metals into the copper layer not only depend causally on the magnetic properties of the SE (III) ions, but the solubility gradient of the sulfometallates Cu ₃ [SE (SO ₄ ) ₃ ] has a significant influence. ₂ in the transition from the comparatively slightly soluble copper salts to the less soluble acids H ₃ [SE (SO ₄ ) ₃ ] (cathodic process). Since the solubility of the sulfates increases significantly after the neodymium, the effect of the heavy SE ions on the deposition process decreases. This crucial equilibrium for the deposition of the structured copper layer forces the high mass transfer in the area of the electrolytic processes in order to be able to rule out stationary, macroscopic precipitations of SE (III) sulfates (salt spots), especially at high molar SE-Cu ratios.

• n = eine ganze Zahl von 1 bis 11, insbesondere eine ganze Zahl von 1 bis 3,
• Z = S oder O, insbesondere S,
• R⁴ = H, C_1-4-Alkyl oder Phenyl,
• R⁵ = H, C_1-4-Alkyl oder Phenyl,
• R⁶ = H, C_1-4-Alkyl oder Phenyl,
• R⁷ = H, C_1-4-Alkyl oder Phenyl,
• R⁸ = H, C_1-4-Alkyl oder Phenyl, und
• R⁹ = H, C_1-4-Alkyl oder Phenyl.

The treatment liquid may additionally contain further control additives and additives which influence the viscosity, thermal conductivity, electrical conductivity and / or the deposition of the metal aggregates. For example, the treatment liquid may comprise an additive of the general formula (I):

HO-CHR ⁸ -CHR ⁹ -Z- (CHR ⁴ -CHR ⁵ -Z) _n -CHR ⁶ -CHR ⁷ -OH (I)

wherein:

• n = an integer from 1 to 11, in particular an integer from 1 to 3,
• Z = S or O, in particular S,
• R ⁴ = H, C _1-4 -alkyl or phenyl,
• R ⁵ = H, C _1-4 -alkyl or phenyl,
• R ^{6 is} H, C _1-4 -alkyl or phenyl,
• R ⁷ = H, C _1-4 -alkyl or phenyl,
• R ⁸ = H, C _1-4 alkyl or phenyl, and
• R ⁹ = H, C _1-4 alkyl or phenyl.

When the compound of formula (I) comprises enantiomers or diastereomers, both the pure enantiomers or diastereomers and the corresponding mixtures can be used.

In particular, in the context of the present invention, C _1-4 -alkyl is methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl or sec-butyl, preferably methyl, ethyl, n-propyl , or n-butyl.

• n = eine ganze Zahl von 1 bis 3,
• Z = S,
• R⁴ = H, Methyl, Ethyl, n-Propyl, oder n-Butyl,
• R⁵ = H, Methyl, Ethyl, n-Propyl, oder n-Butyl,
• R⁶ = H, Methyl, Ethyl, n-Propyl, oder n-Butyl,
• R⁷ = H, Methyl, Ethyl, n-Propyl, oder n-Butyl,
• R⁸ = H, Methyl, Ethyl, n-Propyl, oder n-Butyl, und
• R⁹ = H, Methyl, Ethyl, n-Propyl, oder n-Butyl.

Preferably, in the additive of formula (I):

• n = an integer from 1 to 3,
• Z = S,
• R ⁴ = H, methyl, ethyl, n-propyl, or n-butyl,
• R ⁵ = H, methyl, ethyl, n-propyl, or n-butyl,
• R ⁶ = H, methyl, ethyl, n-propyl, or n-butyl,
• R ⁷ = H, methyl, ethyl, n-propyl, or n-butyl,
• R ⁸ = H, methyl, ethyl, n-propyl, or n-butyl, and
• R ⁹ = H, methyl, ethyl, n-propyl, or n-butyl.

• n = eine ganze Zahl von 1 bis 11,
• Z = S oder O,
• R⁶ = H, Methyl oder Phenyl, und
• R⁷ = H, Methyl oder Phenyl,

wobei vorzugsweise n=1-3 und Z = S.Alternatively, the additive of formula (I) is a compound of formula (II):

HO- (CHR ⁶ -CHR ⁷ -Z) _n -CHR ⁶ -CHR ⁷ -OH (II)

wherein:

• n = an integer from 1 to 11,
• Z = S or O,
• R ⁶ = H, methyl or phenyl, and
• R ⁷ = H, methyl or phenyl,

preferably n = 1-3 and Z = S.

• n = 1 oder 2, insbesondere 1,
• Z = S,
• R⁴ = R⁵ = H oder Methyl,
• R⁶ = R⁹ = H oder Methyl, und
• R⁷ = R⁸ = H oder Methyl.

Most preferably, the additive is a compound of formula (I) wherein:

• n = 1 or 2, in particular 1,
• Z = S,
• R ⁴ = R ⁵ = H or methyl,
• R ⁶ = R ⁹ = H or methyl, and
• R ⁷ = R ⁸ = H or methyl.

• R⁶ = R⁹ = H oder Methyl, und
• R⁷ = R⁸ = H oder Methyl.

More preferably, the additive is a compound of formula (III):

HO-CHR ⁸ -CHR ⁹ -S-CH ₂ -CH ₂ -S-CHR ⁶ -CHR ⁷ -OH (III)

wherein

• R ⁶ = R ⁹ = H or methyl, and
• R ⁷ = R ⁸ = H or methyl.

A particularly preferred additive of the general formula (I) which can be used in the treatment liquid in the process according to the invention is 1,8-dihydroxy-3,6-dithiaoctane (DTO).

The additives of the formula (I) are commercially available or can be obtained by known chemical synthesis methods or analogously to these.

In addition, the following additives are applicable for influencing the surface tension and the dissolution rate of finest gas bubbles:

Surface-active substances of the general formula: C _n H _{2n + 1} (OC ₂ H ₄ ) _x -O- (H, C _m H _{2m + 1} ) with n = 8 to 18, and x = 3 to 9, m = 1 to 4 C _n H _{2n + 1} (OC ₃ H ₆ ) _y -OH with n = 8 to 16 and y = 1 to 3. C _n H _{2n + 1} (OC ₂ H ₄ ) _v - (OC ₃ H ₆ ) _w -OH with n = 10 to 16 and v = 4 to 5, w = 2 to 4, from w = 1 / 2v to w + 1 = v

The possible surfactants are added individually or in admixture, the total concentration in the electrolyte always having to be below the saturation limit, usually below 0.05 wt .-%. It is advantageous to use the end-etherified polyethoxylates which are less sensitive to oxidation at the anode.

In one embodiment of the invention, the method according to the invention is carried out according to the central conductor principle, ie, the flat metal workpiece is contacted neither cathodically nor anodically but is anodically (positively) polarized by at least one cathode and then cathodically (negatively) polarized by at least one anode. In this case, the current transfer to the flat metal workpiece does not take place by direct contacting of the flat metal workpiece via a contact element connected to a current source (eg a current roller), but through the treatment liquid. In anodic polarization, an anodic dissolution process is induced on a surface of the sheet metal workpiece by removing minute particles and residues or impurities present on the surface of the metal foil, thereby obtaining a clean surface. Furthermore, the topographic features of the metal surface, in particular the roughness peaks, are leveled.

Furthermore, the anodic polarization or the anodic dissolution process induced thereby leads to an activated surface for the subsequent metal deposition. In particular, the surface obtained by the method according to the invention exhibits structural similarity or structural identity to the metal aggregates deposited on the surface of the flat metal workpiece in the subsequent deposition process (epitaxy or syntaxie). Furthermore, due to the fact that the flat metal workpiece is completely covered by the treatment liquid during the entire electrolytic treatment, it can largely be avoided that the defined activation state of the surface is lost due to the contact with the ambient atmosphere. Subsequent cathodic polarization induces a cathodic deposition process in which a metal or metal alloy (i.e., several different metals) is deposited on the surface of the sheet metal workpiece.

The flat metal workpiece used in the present invention is preferably a metal workpiece having a thickness which is at least 100 times, more preferably at least 1000 times, and particularly preferably at least 10000 times smaller than the length and / or width of the metal workpiece. Consequently, the term "surface of the sheet metal workpiece" as a rule meant the area defined by the length and width, not the area defined by the thickness and width or thickness and length. Preferably, the sheet metal workpiece is a metal strip or a metal foil. The term "metal strip" herein refers to a sheet metal workpiece having a given width and a thickness of 100 μm to 1 mm. The term "metal foil" refers to a sheet metal workpiece having a given width and a thickness of 100 μm or less, preferably having a thickness in the range of 10 μm to less than 100 μm.

The flat metal workpiece is usually made entirely of a single metal, in particular copper, tin, silver or iron. However, it can also consist of a metal alloy, for example of at least two of the metals mentioned, preferably of a copper wrought alloy, iron alloy, silver alloy and tin alloy. Also, a flat metal workpiece made of steel can be used. The flat metal workpiece is particularly preferably a copper foil, a copper band, a silver foil, a silver band, a tinned foil or a tinned band, in particular a tinned copper foil or a tinned copper band.

Furthermore, the flat metal workpiece may also consist of two or more layers of a metal or a metal alloy, wherein the layers may be the same or different. Furthermore, the flat metal workpiece may be formed so that at least one and preferably both surfaces of the sheet metal workpiece consist of a metal or a metal alloy and the remaining portion of the sheet metal workpiece may be any material, if this is suitable for use in the inventive method ,

Before use in the method according to the invention, the flat metal workpiece is usually pretreated. Corresponding pretreatment processes are known in the art and include, for example, degreasing, rinsing with water, aqueous surfactant solutions or solvents, and pickling with sulfuric acid.

The sheet metal workpiece is preferably passed through the treatment liquid and past the at least one cathode and the at least one anode during the electrolysis. This is done in a manner that results in the described anodic polarization and cathodic polarization and the induced anodic dissolution process and cathodic deposition process. In the case of endless metal foils or strips, they are usually passed through the treatment liquid using guide elements (eg deflection rollers). If a film conveyor system is used to carry out the process according to the invention, several electrolysis baths (electrolysis cells) can also be connected in series.

In the context of the present invention, many arrangements of the at least one cathode and the at least one anode are conceivable. For example, 1, 2, 3, 4 or more cathodes and 1, 2, 3, 4 or more anodes per electrolysis cell or electrolyte bath can be used. These may be arranged differently (e.g., cathode and anode alternately, first all cathodes and then all anodes, multiple cathodes alternating with multiple anodes, cathodes and anodes disposed only on one side of the sheet metal workpiece or on both sides, etc.).

According to a preferred embodiment, preferably at least one Cathode pair and at least one anode pair used. The two cathodes of the cathode pair and the two anodes of the anode pair are arranged on opposite sides of the flat metal workpiece, so that the flat metal workpiece is located between the two anodes or between the two cathodes. Consequently, anodic or cathodic polarization occurs on both sides of the flat metal workpiece. Such a configuration allows the two-sided modification of the flat metal workpiece with deposited metal aggregates. According to another preferred embodiment, the sheet metal workpiece is first anodically polarized by two cathodes disposed on the same side of the sheet metal workpiece and then cathodically polarized by two anodes both located on the same side of the sheet metal workpiece as the cathodes. Each substrate side (electrode pair) requires a separate rectifier.

Usually, the at least one surface of the flat metal workpiece is first anodically polarized by the at least one cathode and then cathodically polarized by the at least one anode. However, it is also envisaged that the cycle "anodic polarization / cathodic polarization" will be run through several times. Furthermore, the flat metal workpiece can be polarized one or more times anodically and one or more times cathodically in any desired sequence, with the anodic dissolution process typically predominating first and then outweighing the cathodic deposition process. In this case, a phase with dominant dissolution process can be interrupted by a short phase with the deposition process (dominant dissolution process, interrupted by deposition process) and vice versa (dominant deposition process, interrupted by dissolution process). The one or more anodic polarization and the one or more cathodic polarization can, as already mentioned above, be achieved by using a corresponding number of spatially separated anodes or cathodes. However, it is also possible to use electrodes which are selectively switched to positive or negative (contacted) and thus function both as a cathode and as an anode.

The cathodes and anodes are operated with direct current or a pulsed current, usually a pulsed direct current. For this purpose, rectifiers can be used. If the number of electrodes exceeds two (ie more than one Cathode and / or more than one anode), the additional electrodes are preferably operated by an additional rectifier. In the context of the present invention, it is also possible that in at least one working area (cathodic, anodic) each electrode is supplied by a different rectifier, while in another working area a plurality of rectifiers can be connected to one electrode.

As anodes, insoluble or soluble anodes can be used in the process according to the invention. The insoluble anodes typically consist of an inert material (or oxides thereof) such as lead, graphite, titanium, platinum and / or iridium (and / or their oxides). Preferred insoluble anodes are titanium coated with platinum or iridium and / or ruthenium (and / or their oxides). Particularly preferred is an iridium or iridium oxide coated titanium anode. In contrast, the soluble anodes consist of the metal to be coated or the metal alloys to be coated. Examples of suitable soluble anodes are anodes of copper or tin.

Suitable cathodes may be made of the same material as the material of the anodes. As a cathode, for example, a copper cathode can be used. In a preferred embodiment, copper electrodes are used both as the anode and as the cathode.

The working temperature of the treatment liquid, hereinafter also referred to as electrolyte, is preferably between 10 ° C and 60 ° C, more preferably between 20 ° C and 50 ° C. In order to keep the treatment liquid in this temperature range, it can be continuously cooled or heated.

The necessary circulation of the treatment liquid depends on the current density used in the electrodeposition. The circulation is necessary to reduce the thickness of the electric double layer to a sufficient minimum. The circulation in the electrode chamber can be ensured for example by attaching one or more pumps. The circulation serves primarily to maintain the functionality of the electrodes and to avoid salt spots on the film to be treated. The stacking effects which occur due to the sulphatometallates already in electroless rest lead to an extreme primary stress in order to prevent the electrolytic process to start at all. This primary voltage can be lowered so much by the targeted increase in the circulation of the electrode surfaces and the treated material in conjunction with a well-chosen temporal gradient of Stromdichteerhöhung so that these electrolytes are a technical use accessible. The necessary circulation and the current density gradient depend directly on the SE / Cu ratio used and on the real SE ion in the sulfate electrolyte. The highest sensitivity and thus the best possible process adjustment provide lanthanum (III) ions.

The following circulation data given in Table 3 relate to an electrolyte volume in the treatment space of 50 liters, an electrode-foil distance of 20-30 mm and a width and height of the polarization space of 240 mm (H) and 300 mm ( B). In addition to the targeted circulation, the circulation via the filtration bypass delivers 1.2 l / min. <b> Table 3. </ b> Dependence of circulation and current density gradient on La / Cu molar ratio and current density gradient electrolyte La / Cu ratio Circulation in l / min Current density gradient A / dm ² s Pulse shape ^b) Current density in process A / dm ² Electrolyte 1 0.032 1.2 0.66 10001 3.3 Electrolyte 1 0.032 40 ^a) 2.25 10997 22.5 Electrolyte 2 0.064 40 1.13 10997 22.5 Electrolyte 3 0,127 40 0.38 10997 22.5 a) 40 l / min corresponds to a flow on the surfaces of the electrode chamber of approx. 2.65 l / (min * dm ² )
b) The pulse shapes / rates 10001 = 50 mS 1, 50mS = 0; leff = ½ l (1) 10997 = 50ms 1, 50ms 5, 50ms 1, 50ms 7 = 1 cycle; leff = 3.5 l (1)

Preferably, at least one cathode and / or at least one anode of the device is designed as a flow electrode, which comprises an electrode housing with a metal grid, through which the treatment liquid can enter the housing. The electrode housing is at least partially filled with metal balls, which are in contact with each other and with the metal grid. The electrode housing further includes an electrolyte supply for introducing an electrolyte and a flow opening from which the electrolyte that has flowed from the electrolyte supply between the metal balls to the flow opening exits. The flow opening is arranged so that sufficient flow of the working zone, i. of the space between the electrode and the sheet metal workpiece. For this purpose, the flow opening is usually arranged so that the exiting electrolyte flows past the metal grid. Preferably, the flow past substantially parallel to the metal grid.

The flat metal workpiece treated with the method according to the invention is usually subjected to an aftertreatment. Such aftertreatment processes are known in the art and include, for example, rinsing with water or solvents, passivation, for example, with a solution containing chromium (VI), and drying.

An example of a device for carrying out the method according to the invention is a device which has at least one container for receiving a treatment liquid, at least one cathode arranged in the container and at least one arranged in the container anode, wherein the at least one cathode and the at least one anode are connected to a power source and wherein the flat metal workpiece is not connected to a power source.

Usually, the electrode housing also includes a lid to prevent falling out of the metal balls and ensure a defined flow through the flow electrode with electrolyte. For example, the lid may be releasably connected to the electrode housing with thumbscrews and may further include contacts for connection to a power source. In operation, the flow electrode is connected anodically or cathodically to a current source, wherein usually the metal grid is contacted anodically or cathodically.

The electrolyte which has passed through the metal balls is preferably collected in an electrolyte channel and then supplied to the flow port. The electrolyte channel and the flow opening are preferably located in the bottom of the electrode housing. The flow opening is preferably designed as a flow lip, which preferably extends over the entire length of the metal grid in the bottom of the electrode housing. If a filter fleece arranged in front of the metal grid is used as anode bag, the flow opening is arranged such that the electrolyte emerges in front of the filter fleece and flows along it, substantially laminar.

The electrode housing may for example consist of a plastic, such as polypropylene. The metal balls may consist of the metals mentioned above for the anode and cathode. Preferably, at least one anode is designed in the form of the flow electrode described above. In the case of the anode, the metal balls are preferably made of the metal or metals to be deposited on the sheet metal workpiece. Preferably, the metal balls are copper balls. The metal grid is preferably an expanded metal grid (expanded metal blend surface), in particular a titanium expanded metal.

FIG. 1 schematically shows an embodiment of a dissolving / deposition cell 30 for carrying out the method according to the invention for the surface treatment of a flat metal workpiece 32, in this case a metal foil. The dissolving / separating cell 30 has a trough-like, upwardly open container 31, in which a treatment liquid 36 is located. The dissolution / separation cell 30 also has a first, second and third diverting rollers 34a, 34b and 34c and a first working electrode consisting of two parallel cathodes 40a and 40b and a second working electrode consisting of two parallel arranged anodes 44a and 44b. The cathodes 40 a and 40 b and the anodes 44 a and 44 b are connected to a current source 45. The first and third deflection rollers 34a, 34c are arranged above the container 31 outside the treatment liquid 36 and above the first and second working electrodes, while the second deflection roller is located at the bottom of the container 31 within the treatment liquid and below the working electrodes. Furthermore, the dissolution / deposition cell 30 has a separator 48 for reducing reactive currents.

The flat metal workpiece 32 enters the treatment liquid 36 via the first deflection roller 34a and passes between the two cathodes 40a, 40b so that they are located on one of the two sides of the continuous flat metal workpiece 32. Neither the flat metal workpiece 32 nor the first deflection roller 34a is connected to a power source. The region 38a of the flat metal workpiece 32 located between the two cathodes 40a, 40b is positively (anodically) polarized by the two cathodes 40a, 40b. The two cathodes 40a, 40b define a resolution region 42. In the enlarged and schematically illustrated section of the dissolution region 42, impurities present on the surface of the sheet metal workpiece 32 and any foreign metals present and / or certain (eg uneven) metal structures are largely eliminated. As a result, a contaminant-free, homogeneous and defined surface of the sheet metal workpiece 32 is obtained, which is suitable for obtaining defined metal structures in the subsequent deposition step.

After passing through the cathodes 40a, 40b, ie the dissolution region 42, the flat metal workpiece 32 is passed via the second deflection roller 34b, which is likewise not connected to a power source, between the two anodes 44a, 44b, which are each on one of the two sides of the flat metal workpiece 32 and form the second working electrode. Through the two anodes 44a, 44b, a region 38b of the flat metal workpiece 32 is negatively (cathodically) polarized. The two anodes define a deposition region 46. In the enlarged and schematically illustrated section of the deposition region 46, the positively charged metal ions of the treatment liquid 36 migrate to the negatively polarized surface of the deposition liquid flat metal workpiece 32 and divorced in a defined manner on the surface of the flat metal workpiece 32. After passing through the deposition region 46, the sheet metal workpiece 32 runs out of the treatment liquid 36 and over the third deflection roller 34c, which is not connected to a power source.
Another object of the present invention is a flat metal workpiece, which was produced by the method according to the invention. It has surprisingly been found that the method according to the invention results in the formation of copper aggregates on the surface of the flat metal workpiece, these metal aggregates being in the form of balls set with standing lamellae. This distinguishes them from the columnar dendrites obtained by the conventional methods of the prior art.
FIG. 2 shows a dark field image (Nikon Eclipse ME600 reflected light microscope with dark field unit, camera Leica DFC290, objectives 100x, 50x, 20x, 10x, 5x, software Leica Application Suite 2.6.0 R1, magnification 500 times) a copper foil surface, which according to the method of the invention by Deposition of La / Cu from sulfuric acid electrolyte with a La concentration of 14.0 g / l, a Cu concentration of 50.3 g / l and a [La]: [Cu] molar ratio of 0.127 (electrolyte 3) in the following film conveyor system has been modified.
At this magnification, the spherical metal aggregates are clearly visible on the copper foil surface.
FIG. 3 shows a SEM micrograph of an electrolytic with sulfuric acid neodymium-copper electrolyte having a Nd: Cu molar ratio of 0.032 according to the inventive process treated copper foil surface in 10000-fold magnification. The image reproduces a section of a spherical metal aggregate on the copper foil surface and makes visible its lamellar structure.
FIG. 4 12 shows a dark field image (Nikon Eclipse ME600 reflected light microscope with dark field unit, Leica DFC290 camera, objectives 100x, 50x, 20x, 10x, 5x, software Leica Application Suite 2.6.0 R1, magnification 500x) of a copper foil surface prepared according to the method of the invention by deposition of Cu from sulfuric acid electrolyte with a Cu concentration of 7.0 g / l (electrolyte) was modified in the film flow system described below. At this Magnification, the stalked metal aggregates on the copper foil surface clearly visible.

The roughness of the metal surface increases slightly due to the deposition of the metal aggregates. For example, after deposition of the metal aggregates on a copper foil, the mean roughness values Ra and Rz, determined in accordance with DIN EN ISO 4288: 1998, are preferably in the range from 0.22 to 0.32 μm and in particular in the range from 0.24 to 0.28 μm for Ra and preferably in the range of 1.4 to 2.1 μm and in particular in the range of 1.6 to 1.9 μm for Rz. On the other hand, for example, a copper foil before deposition has roughness values of about 0.20 μm for Ra and 1.3 μm for Rz.

It has surprisingly been found that the adhesion of the metal surface, which is obtained by the deposition of aggregates in the form of standing with lamellar balls on a surface of a flat metal workpiece according to the inventive method is surprisingly high. The adhesiveness, determined according to the 180 ° peel test described below using a FR-4 epoxy resin and expressed as peel strength in N / mm, is preferably at or above 1.5 N / mm. In a copper foil or a copper tape, the peel strengths are preferably 1.5 to 3.0 N / mm, more preferably 1.8 to 3.0 N / mm.

The sheet metal workpieces of the present invention, because of their excellent adhesiveness, can be used as a substrate for the formation of solid adhesives having a variety of materials. In particular, lead the metal aggregates on the surface of the sheet metal workpiece during pressing or rolling (roll cladding) with the same or a different material when painting with or without subsequent curing / crosslinking or bonding to a solid adhesive bond. Suitable adhesion partners for the metal workpiece according to the invention are a large number of materials, for example thermoplastics such as PA 66, PI and PET, synthetic resins (epoxies), adhesives, lacquers and pastes, such as graphite pastes.

The present invention therefore also relates to the use of the metal workpieces produced according to the method of the invention as a substrate for the formation of solid adhesive dressings. In this case, the flat metal workpieces according to the invention can be used for a variety of applications. exemplary For example, laminates of copper with PET can be cited for shielding cables and plug and device housings against electromagnetic interference, particularly in signal transmission. Furthermore, the use as an electrical conductor in the production of MID (Molded Interconnect Devices) circuits should be mentioned. These are circuits based on hot stamping of metallic foils on thermoplastic substrates. Another application is as a substrate for electrode material in battery technology. In particular, the flat metal workpieces according to the invention can also be used in the production of stable compounds required in printed circuit board technology for the production of copper laminates. Especially in the production of printed circuit boards, the adhesive strength of the metallic conductor on the substrate (eg FR-4) is of central importance. This is due, on the one hand, to the process steps required in the production (etching, drilling, pressing) and, on the other hand, to the stress on the printed circuit board in the final product itself.

EXAMPLES materials

As the electrolytes for use in the following examples, various sulfuric acid sulfate electrolytes of copper with or without the addition of lanthanum conducting salt were used. The composition of these electrolytes is shown in Table 4. <b> Table 4. </ b> Properties and composition of the electrolytes used in Examples Electrolyte 0 ^a) Electrolyte 1 Electrolyte 2 Electrolyte 3 Density (g / cm ³ ) 1.07 1.19 ± 0.02 1.21 ± 0.02 1.24 ± 0.02 pH value ^b) 1.9 ± 0.3 1.9 ± 0.3 1.9 ± 0.3 1.9 ± 0.3 Copper content (g / l) 7.0 48.9 49.5 50.3 Lanthanum content (g / l) 0 3.41 6.9 14.0 Sulphate content (g / l) 69.4 77.5 80.7 94.2 Sulfuric acid (g / l) 60.0 61.5 62.3 63.3 [La]: [Cu] 0 0.032 0.064 0,127 ^a) : electrolyte 0: for comparison
^b) : pH determined for a concentration of electrolytes of 10 g / l

All La-Cu electrolytes (Electrolytes 1, 2, and 3) contain less than 0.2 g / L of trace lanthanides such as praseodymium, neodymium, and samarium.

electrolyzers

In the examples described herein, on the one hand, a film pass line and, on the other hand, a static electrolysis set were used.

Sheet-through system

The film conveyor system used is designed for films or tapes up to a width of 330 mm. The system has a rewinder and a reel with electronic tension control. The control possibilities include the current intensity of the individual electrode segments, strip tension, belt speed and temperature of the electrolyte. The rectifiers used are from the company plating electronic type pe86CW-6-424-960-4 with 4 outputs. The maximum pulse current is 960 A, the maximum continuous current is 424 A. The temporal course of the current can be defined as a pulse sequence via the associated software.

The electrolytic cell of the film conveyor system used comprises a cathode and an anode for one-sided electrolytic deposition. The cathode and the anode are positioned parallel to the film run and arranged so that during the film run the same side or surface of the metal foil is opposite first to the cathode and then to the anode. Furthermore, the cathode and the anode are completely surrounded by electrolyte. Although only one cathode and one anode are used in the experiments described herein, a variety of different configurations may be used, for example, a dual cathode and a double anode for double-sided electrodeposition, or two sequentially arranged cathodes and anodes.

As electrodes (anode and cathode) either a tripartite convection electrode or a flow electrode are used in the experiments described below. These are connected to rectifiers (type pe86CW-6-424-960-4 with 4 outputs from plating electronic, maximum pulse current 960 A, maximum continuous current 424 A). The temporal course of the current is as a pulse sequence over a corresponding software definable. Furthermore, the current intensity of the individual electrodes, the belt speed and tension as well as the electrolyte temperature can be regulated.

The three-part convection electrode used has three electrode segments consisting of a copper sheet. Although the individual electrode segments can be controlled separately via a rectifier, all electrode segments were switched to the same pole in the following experiments. The electrode is located in an anodic bag made of polypropylene fabric. The necessary flow is generated by means of a B2 rod pump from Lutz (total 40 l / min distributed over 2 electrodes).

The flow electrode used comprises an electrode housing made of polypropylene and a high-current titanium contact frame with a covering surface made of titanium expanded metal, which is backfilled with copper balls. The electrode is located in an anode bag made of PP fabric. The flow rate is possible up to 20 l / min. The electrolyte is introduced into the flow electrode via an electrolyte feed, flows past the metal balls in the direction of the housing bottom of the electrode housing and is received by an electrolyte channel in the bottom of the electrode housing. The electrolyte then exits the electrolyte channel via a flow opening in the form of a flow lip and flows upwards past the metal grid. In the used film flow system, the electrolyte passes after passing through the flow electrode in the electrolytic bath and from there via an overflow into a reservoir, from which the electrolyte is then pumped again into the flow electrode.

The flow electrode described above and used in the following examples represents only one example of a flow electrode which can be used according to the invention. It will be clear to a person skilled in the art that numerous refinements, modifications and / or modifications are conceivable.

Static electrolysis device

This electrolysis device was used to simulate the typical change of the polarization of the same surface of the sheet metal workpiece with the economical use of material.

The static electrolytic cell comprises a 1000 ml beaker filled with an electrolyte (900 ml). The beaker stands on a stirrer. The stirrer is used to heat the electrolyte, the temperature is constantly checked by a thermocouple with stainless steel sheath and kept constant within +/- 2 ° C. Stirring speed is maintained at 1000 rpm and agitation is transferred to the electrolyte solution through a 40xd6 round magnetic stir bar (PTFE).

Above the beaker there is a cover plate made of PP, which is placed over the beaker and has one electrode each on each side at a distance of 30 mm. These electrodes may be made of inert material or of the material of the film to be treated. The replacement is possible within a few minutes without any problems. These electrodes are flat sheets that dive parallel to each other and each perpendicular to the electrolyte solution. The single-sided, immersed surface is between 60 mm x 80 mm and 60 mm x 100 mm per electrode. In the middle of the plastic plate was provided parallel to the inert electrodes with an opening of 20 mm x 80 mm, through which the flexible film holder can be inserted into the cell. This film holder was therefore designed to be flexible, so that the film, once clamped, then the entire process including the pre- and post-treatment steps (eg cleaning / sink / sink, pickling / pickling / sink / sink, electrolysis / sink / sink, passivation / sink / VE-sink) in the same holder and must be removed from the holder only after the last sink for drying. The film holder consists of two PP frames with a window of 80 mm x 60 mm, in which the film is clamped. The clamping screws are made of PA6 plastic. The lower clamping screws serve only to tension the film, the upper clamping screws additionally serve to produce a releasable press contact to a TiPt expanded metal grid. This contact point dips into the solution, so that the film is completely immersed in the electrolyte and the contact point is blinded by the frame of the film holder relative to the field of the cell. The expanded metal used for contacting protrudes at the top of the cell and is powered by a crocodile clip with power. For the power supply a power supply of the type Statron with preselectable current strength and indication of the corresponding voltage is used. Between the power supply and the electrolysis cell is a Polwendeschalter, whereby the polarity of the film and the electrodes during the experiment in any order and in any time can be turned (exchanged).

test method Test Procedure 1 - Adhesion Test

An adhesive tape (Tesafilm® Transparent 57404-00002) was placed over the electrolytically treated, dry, cold and at least 15min deposited metal foil surface and pressed with a soft roller firmly on the surface. Care was taken to ensure that no air bubbles formed between the adhesive tape and the film surface. After a period of 30 seconds after the adhesive strip was pressed on, it was caught on its projection and peeled off from the retained metal foil. In this case, a pulling rate of 2 to 3 seconds was observed for a length of 8 cm.

The peeled tape was then adhered to a white piece of paper and the color change caused by metal aggregates being torn from the film surface and remaining on the tape. Furthermore, it was judged whether the adhesive layer of the Tesafilms after peeling completely or partially remained on the surface of the metal foil.

Test method 2 - Peel strength test

The peel strength was determined according to DIN EN 60249 on a Zwick BZ2 / TN1 S peeling tool with Xforce HP 500 N load cell and software testXpert 12.3. For this purpose, the samples were cut from a pressed composite panel and peeled or peeled the film at an angle of 180 °. The pressed composite panel was produced by pressing the film with a plastic substrate at a temperature of 160 ± 10 ° C and a compression pressure of 120 ± 5 bar over a period of 60 ± 5 min. The results of the peel test are given in N / mm.

Example 1. Copper deposition on copper foil by means of a film flow system using various sulfuric copper electrolytes with or without the addition of La-Leitsalz

• Entfettung: Tauchdurchlauf mit elektrolytischer Unterstützung, 45°C, alkalischer Reiniger
• Spüle: Wasser, Tauchdurchlauf, 45°C
• Dekapierung: Schwefelsäure 4%ig in Wasser, Tauchdurchlauf, 30 - 35°C
• Spüle: Wasser, Tauchdurchlauf, Raumtemperatur
• Spüle: Wasser, Tauchdurchlauf, Raumtemperatur

A copper foil having a thickness of 0.035 mm and a width of 300 mm in a hard-rolling structural state was first subjected to a pretreatment comprising the following steps in the order given:

• Degreasing: immersion pass with electrolytic support, 45 ° C, alkaline cleaner
• Sink: water, dipping, 45 ° C
• Pickling: Sulfuric acid 4% in water, immersion run, 30 - 35 ° C
• Sink: water, immersion run, room temperature
• Sink: water, immersion run, room temperature

• Bandgeschwindigkeit: 1 m/min,
• Mittlere Stromstärke: 100 A,
• Pulssequenz: 10 ms bei 200 A, 10 ms Pause,
• Elektrolyttemperatur: 50 ± 2 °C,
• Umwälzung mittels Stabpumpe mit 40 l/min.

The thus pretreated copper foil was then surface-modified in the described film flow system using the electrolytes of Table 4 (electrolyte 0, electrolyte 1, electrolyte 2, electrolyte 3) and with the following process parameters:

• Belt speed: 1 m / min,
• Average current: 100 A,
• Pulse sequence: 10 ms at 200 A, 10 ms pause,
• Electrolyte temperature: 50 ± 2 ° C,
• Recirculation by means of a rod pump with 40 l / min.

• Spüle: Wasser, Tauchdurchlauf, Raumtemperatur
• Spüle: Wasser, Tauchdurchlauf, Raumtemperatur
• Passivierung: Chrom(VI)-haltige Lösung, Tauchdurchlauf, Raumtemperatur
• Spüle: Wasser, Tauchdurchlauf, Raumtemperatur
• Spüle: Vollentsalztes Wasser, Abnebeln, Raumtemperatur
• Trocknung mit Warmluft 90°C

After passing through the electrolysis apparatus, the surface-modified copper foil was subjected to a post-treatment comprising the following steps in the order given:

• Sink: water, immersion run, room temperature
• Sink: water, immersion run, room temperature
• Passivation: chromium (VI) -containing solution, immersion pass, room temperature
• Sink: water, immersion run, room temperature
• Sink: Demineralized water, misting, room temperature
• Drying with warm air 90 ° C

The surface-modified films obtained with the electrolytes 1, 2 and 3 showed a uniform distribution of deposited spherical copper aggregates on the film surface. FIG. 2 shows this with the example of an electrolyte 3 obtained Surface. In FIG. 4 For example, the surface obtained with the electrolyte 0 is shown with stalky growths for comparison.

Moreover, the film surfaces with lamellar spherical aggregates obtained with the electrolytes 1, 2 and 3 had excellent adhesive strengths of adhesives in the adhesion test by means of Tesafilm. The adhesion between the modified metal foil surface and the adhesive on the adhesive strip is so high that when the adhesive strip is peeled off, the bond between adhesive and plastic carrier breaks and the adhesive layer of the tesa film remains on the film surface. On the other hand, in the case of the metal foil modified with electrolyte 0 (Cu electrolyte without La) with stalked treatment, the detachment of the treatment is observed when the adhesive strip is removed.

Also in the peel test excellent adhesion strengths between 1.7 and 2.8 N / mm were obtained. The determined peel strengths correlated with increasing surface density of the deposited metal aggregates. The results of the peel tests are summarized in Table 5 below. <b> Table 5 </ b> Peel strengths of FR-4 pressed copper surfaces (V = film speed, I = average current, J = current density, Q = charge density) electrolyte V (m / min) I (A) J (A / dm ² ) Q (C / dm ² ) pulse shape Peel strength (N / mm) Electrolyte 2 2.5 100 13.9 80 10997 * 2.8 ± 0.2 Electrolyte 2 1 150 20.8 300 10997 * 2.8 ± 0.2 Electrolyte 2 1 100 13.9 200 10997 * 1.7 ± 0.2 Electrolyte 2 1 100 13.9 200 10001 ** 2.0 ± 0.2 Electrolyte 2 2 190 26.4 190 10997 * 2.0 ± 0.2 Electrolyte 3 1 100 13.9 200 10997 * 2.4 ± 0.2 Electrolyte 0 1 45 1.5 260 10001 * 1.2 ± 0.2 * Pulse shape 10997 means: pause for 50 ms; Power of magnitude A (namely 166 A, 250 A, 166 A, 317 A and 166 A, respectively) for 50 ms; Break for 50 ms; and current of magnitude B (greater than A) (namely, 233A, 350A, 233A, 443A, and 233A, respectively) for 50 ms (this gives a mean current (referenced to 50ms) of I = 100A, 150A , 100 A, 190 A or 100 A).
** Pulse shape 10001 means: current of magnitude C (here 200 A) for 50 ms; Pause for 10 ms.

Example 2. Incorporation of rare earths (SE) into the aggregates on the surface of copper foil modified with SE-Cu electrolytes

• Vorreinigung: Purax 6029PUS, 40 g/l, 60°C, stromlos, 10s.
• Spüle: Wasser
• Feinreinigung: Velocit 1127M, 25 g/l, 60°C, stromlos, 10s.
• Spüle: Wasser
• Beize/Dekapierung: Schwefelsäure (7%ig in Wasser), 25°C - 35°C.
• Spüle: Wasser

A copper foil having a thickness of 0.035 mm and a width of 300 mm in a hard-rolling structural state was first subjected to a pretreatment comprising the following steps in the order given:

• Pre-cleaning: Purax 6029PUS, 40 g / l, 60 ° C, de-energized, 10s.
• Sink: water
• Fine cleaning: Velocit 1127M, 25 g / l, 60 ° C, de-energized, 10s.
• Sink: water
• Pickling / pickling: sulfuric acid (7% in water), 25 ° C - 35 ° C.
• Sink: water

• Spüle: Wasser
• Passivierung: Lösung von 6 g Kaliumdichromat in Wasser bei Raumtemperatur.
• Spüle: Wasser
• Trocknung mit Warmluft zwischen 90°C und 120°C.

The thus pretreated copper foil was then surface-modified in the described static electrolysis arrangement using electrolyte 1 and electrolyte 2 at room temperature with a charge density of 541 C / dm ² :
After passing through the electrolysis apparatus, the surface-modified copper foil was subjected to a post-treatment comprising the following steps in the order given:

• Sink: water
• Passivation: Dissolve 6 g potassium dichromate in water at room temperature.
• Sink: water
• Drying with warm air between 90 ° C and 120 ° C.

In further investigations in the context of this example, the lanthanum was replaced by equimolar amounts of yttrium, neodymium, gadolinium or dysprosium in the electrolytic treatment electrolyte 1 and the surface modification was repeated with otherwise identical parameters.

The layers deposited using the various electrolytes were filtered by nitric acid solution ICP-OES (argon plasma, Perkin Elmer, Optima 3000DV, axial registration emission; the concentrations of 0.1 mg / l, 1 mg / l and 10 mg / l of the respective SE metal were used as standards). The results are shown in Table 6. <b> Table 6 </ b> Concentration of the found inert ions in the deposited layer, based on the treated surface in μmol / m <sup> 2 </ sup> (from acidic SE-Cu electrolyte). Inert Ion Concentration in the aggregates Lanthanum (electrolyte 1) 0 Lanthanum (electrolyte 2) 0 yttrium 0 neodymium 42.0 gadolinium 13.3 dysprosium 13.5

This example shows that lanthanum and yttrium are not incorporated into the deposited aggregates after electrolytic surface modification of a copper foil with La-Cu or Y-Cu electrolytes. On the other hand, with neodymium, gadolinium and dysprosium after the nitric acid decomposition of the deposited aggregates, these were recovered as paramagnetic inert ions.

Claims (12)

1. Method for the electrolytic surface modification of a flat metal workpiece (32), in which
   at least one surface of the flat metal workpiece (32) is anodically poled in a treatment liquid (36) and an anodic dissolving process is thereby induced, and then
   the at least one surface of the flat metal workpiece (32) is cathodically poled in the treatment liquid (36) and a cathodic deposition process is thereby induced for the deposition of one or more metals on the at least one surface of the flat metal workpiece,
   characterized in that
   a conductive liquid based on sulphuric acid/sulphate solutions of copper is used as treatment liquid (36) and the treatment liquid further contains one or more members selected from the group consisting of: yttrium, lanthanum and lanthanoids, wherein the ratio between (i) the sum of the amount-of-substance fractions of yttrium, lanthanum and/or the lanthanoids, and (ii) the amount-of-substance fraction of copper is 0.0182 or more, preferably 0.0182 to 0.127.
2. Method according to claim 1, wherein the flat metal workpiece (32) is anodically polarized by at least one cathode (40a, 40b) without direct contacting for the induction of the dissolving process, the flat metal workpiece (32) is cathodically polarized by at least one anode (44a, 44b) without direct contacting for the induction of the deposition process, and the cathode (40a, 40b) and the anode (44a, 44b) are arranged in such a way that treatment liquid (36) is located between anode (44a, 44b) and metal workpiece (32) and between cathode (40a, 40b) and metal workpiece (32).
3. Method according to claim 1 or 2, wherein the concentration of the sum of yttrium, lanthanum and lanthanoids in the treatment liquid (36) is 0.01 mol/l or more and is preferably in the range of from 0.014 mol/l to 0.35 mol/l, in particular in the range of from 0.02 mol/l to 0.125 mol/l.
4. Method according to one of claims 1 to 3, wherein the treatment liquid (36) contains lanthanum, and wherein the lanthanum is preferably supplied in the form of lanthanum oxide.
5. Method according to one of claims 1 to 4, wherein the treatment liquid (36) comprises an additive of the general formula (I):
   
           HO-CHR⁸-CHR⁹-Z-(CHR⁴-CHR⁵-Z)_n-CHR⁶-CHR⁷-OH     (I)
   
   in which:

   n = an integer from 1 to 11, in particular an integer from 1 to 3,

   Z = S or O, in particular S,

   R⁴ = H, C_1-4-alkyl or phenyl,

   R⁵ = H, C_1-4-alkyl or phenyl,

   R⁶ = H, C_1-4-alkyl or phenyl,

   R⁷ = H, C_1-4-alkyl or phenyl,

   R⁸ = H, C_1-4-alkyl or phenyl, and

   R⁹ = H, C_1-4-alkyl or phenyl.
6. Method according to claim 5, in which:

   n = an integer from 1 to 3,

   Z = S,

   R⁴ = H, methyl, ethyl, n-propyl, or n-butyl,

   R⁵ = H, methyl, ethyl, n-propyl, or n-butyl,

   R⁶ = H, methyl, ethyl, n-propyl, or n-butyl,

   R⁷ = H, methyl, ethyl, n-propyl, or n-butyl,

   R⁸ = H, methyl, ethyl, n-propyl, or n-butyl, and

   R⁹ = H, methyl, ethyl, n-propyl, or n-butyl.
7. Method according to claim 6, wherein the additive is 1,8-dihydroxy-3,6-dithiaoctane.
8. Method according to one of claims 1 to 7, wherein a metal strip or a metal foil is used as flat metal workpiece (32).
9. Flat metal workpiece obtained according to the method according to one of claims 1 to 8, wherein copper aggregates are located on the surface thereof.
10. Flat metal workpiece according to claim 9, further characterized in that lanthanoid ions are incorporated into the copper aggregates.
11. Use of the flat metal workpiece according to one of claims 9 to 10 as substrate for the formation of strong adhesive bonds with other materials.
12. Use according to claim 11, wherein the other materials are selected from thermoplastics, synthetic resins, adhesives, lacquers and pastes.

Images