US20160319448A1 - Method for electrolytic surface modification of flat metal workpieces in copper-sulfate treatment liquid containing sulfate-metallates - Google Patents

Method for electrolytic surface modification of flat metal workpieces in copper-sulfate treatment liquid containing sulfate-metallates Download PDF

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Publication number
US20160319448A1
US20160319448A1 US15/105,824 US201415105824A US2016319448A1 US 20160319448 A1 US20160319448 A1 US 20160319448A1 US 201415105824 A US201415105824 A US 201415105824A US 2016319448 A1 US2016319448 A1 US 2016319448A1
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Prior art keywords
metal workpiece
flat metal
copper
treatment liquid
electrolyte
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US15/105,824
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English (en)
Inventor
Fabian Distelrath
Thomas Booz
Andreas Seidel
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Schlenk Metallfolien GmbH and Co KG
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Schlenk Metallfolien GmbH and Co KG
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Assigned to SCHLENK METALLFOLIEN GMBH & CO. KG reassignment SCHLENK METALLFOLIEN GMBH & CO. KG ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: BOOZ, THOMAS, SEIDEL, ANDREAS, DISTELRATH, FABIAN
Publication of US20160319448A1 publication Critical patent/US20160319448A1/en
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    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
    • C25D3/00—Electroplating: Baths therefor
    • C25D3/02—Electroplating: Baths therefor from solutions
    • C25D3/38—Electroplating: Baths therefor from solutions of copper
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
    • C25D3/00—Electroplating: Baths therefor
    • C25D3/02—Electroplating: Baths therefor from solutions
    • C25D3/56—Electroplating: Baths therefor from solutions of alloys
    • C25D3/58—Electroplating: Baths therefor from solutions of alloys containing more than 50% by weight of copper
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
    • C25D7/00—Electroplating characterised by the article coated
    • C25D7/06—Wires; Strips; Foils
    • C25D7/0614—Strips or foils
    • C25D7/0628—In vertical cells
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
    • C25D7/00—Electroplating characterised by the article coated
    • C25D7/06—Wires; Strips; Foils
    • C25D7/0614—Strips or foils
    • C25D7/0664—Isolating rolls
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
    • C25D7/00—Electroplating characterised by the article coated
    • C25D7/06—Wires; Strips; Foils
    • C25D7/0614—Strips or foils
    • C25D7/0692—Regulating the thickness of the coating
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25F—PROCESSES FOR THE ELECTROLYTIC REMOVAL OF MATERIALS FROM OBJECTS; APPARATUS THEREFOR
    • C25F7/00—Constructional parts, or assemblies thereof, of cells for electrolytic removal of material from objects; Servicing or operating
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
    • C25D5/00—Electroplating characterised by the process; Pretreatment or after-treatment of workpieces
    • C25D5/34—Pretreatment of metallic surfaces to be electroplated

Definitions

  • the present invention relates to a method for the electrolytic surface modification of a flat metal workpiece by deposition of copper aggregates.
  • the invention further relates to the flat metal workpieces produced with this method and to the use of the metal workpieces as substrate for the formation of strong adhesive bonds with a plurality of materials.
  • the use of as few components as possible in the bonding zone is advantageous because here the release of disruptive substances is less likely and because the failure of the bond can be kept to a minimum.
  • the bonds are preferably produced from a brushed metal surface or one modified by treatment and the desired material to be rolled, pressed or drawn on.
  • the electrolytic coating of a metal surface with a metal or a metal alloy represents a known method for the surface treatment of a metal workpiece, such as for example a metal strip or a sheet.
  • a metal workpiece such as for example a metal strip or a sheet.
  • the strip is guided through one or more electrolytic cells.
  • the strip is usually brought into a solid-solid connection with the negative terminal of a rectifier via so-called current rolls.
  • the strip consequently serves as negative electrode, i.e. as cathode.
  • the positive electrode i.e. the anode, is formed as a pair of electrodes, wherein the strip runs through between the two electrodes.
  • the metal workpiece to be coated is provided with a substantially level metal coating uniformly on all sides. Even if metal workpieces having a relatively rough surface nature are used, the surface is leveled. However, for applications in which 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 a mechanical engagement in topographical features of the adhesion partners. If this is not or is not sufficiently the case, the adhesion deteriorates. Thus, poor adhesion between a metal surface and the same or a different material, for example a lacquer layer, a paint layer or an adhesive can lead to products which are of inferior quality or even unusable.
  • a lacquer layer for example a lacquer layer, a paint layer or an adhesive
  • Anodizing is known as an electrolytic process for improving the adhesion to metal surfaces.
  • a regularly structured, porous oxide layer is formed on the surface of a metal workpiece connected as anode using an acidic electrolyte, such as e.g. sulphuric, phosphoric or chromic acid.
  • the pores enable the mechanical engagement of the anodized metal workpiece with another material, such as a paint, lacquer or adhesive layer.
  • anodizing is limited to a few metal materials, such as for example aluminium, titanium and alloys thereof. Above all, anodizing aluminium is industrially significant (Eloxal process; electrolytic oxidation of aluminium).
  • an aluminium oxide layer with a porous structure forms on the surface of the aluminium material.
  • An improvement in the adhesion can also be achieved by inserting an earlier step for the electrolytic pre-treatment of the surface to be coated.
  • the metal workpiece before the actual cathodic deposition process, the metal workpiece can be subjected to an anodic treatment in which an erosion process is induced in which tiny particles and residues or impurities located on the surface of the metal foil are removed and a bright surface is obtained.
  • anodic and cathodic polarization can be effected in a similar way to the conventional galvanic coating through solid-solid contact or, in a further developed process according to the neutral conductor principle, be a contactless polarization.
  • the columnar shape of the deposited aggregates limits the adhesion in the bond.
  • the adhesion in the bond improves with the number of aggregates per unit of area. It always strives towards a threshold value which consists in the tear resistance/breaking strength of the aggregates themselves.
  • the adhesive bond is substantially dependent on the flow behaviour of the plastics to be pressed on, in particular when the flow behaviour is so poor that the plastic does not reach the base of the treatment and only undercuts form on the tips of the aggregates.
  • the bond can then be compared to a plastic plateau on metal stakes. Even if such an adhesive bond is sufficiently good, there remain cavities in the bond at the base of the conventional aggregates of the treatment, into which aggressive chemicals can penetrate and can damage or destroy the adhesive bond through corrosion.
  • a further object of the invention is the provision of a method for modifying/converting the surface of a flat metal workpiece by deposition of a copper layer doped with rare earth elements.
  • the method according to the invention provides a simple and efficient method for increasing the adhesive strength of flat metal workpieces.
  • the present invention provides a method for the electrolytic surface modification of a flat metal workpiece, in which at least one surface of the flat metal workpiece is anodically poled in a treatment liquid and an anodic dissolving process is thereby induced, and then the at least one surface of the flat metal workpiece is cathodically poled in the treatment liquid 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.
  • the treatment liquids used in the method according to the invention are conductive liquids based on sulphuric acid/sulphate solutions of copper. They are produced simply by dissolving suitable salts or oxides of copper in aqueous sulphuric acid.
  • the quantity of sulphuric acid used is preferably chosen such that a residual concentration of free sulphuric acid remains after the dissolving. This residual concentration of free sulphuric acid is preferably at least 0.664 mol/l.
  • the molar ratio (i.e. the ratio of the amount-of-substance fractions) between copper ions and free sulphuric acid is preferably in the range of from 1.05 to 1.25, more preferably 1.10 to 1.20, in particular in the range of from 1.15 to 1.17. In a specific embodiment, the ratio is approximately 1.16.
  • copper(II) sulphate pentahydrate, copper(II) oxide, copper(II) carbonate or basic copper(II) carbonate are suitable as copper source.
  • one or more conducting salts are added to the treatment liquid.
  • the element(III) oxides and the element(III) carbonates are suitable, among other things, as source for yttrium, lanthanum and the lanthanoids. Lanthanum oxide is particularly preferred.
  • the yttrium, lanthanum or lanthanoid salts are added to the treatment liquid in a quantity such that the molar ratio between (i) the sum of the amount-of-substance fractions of Y, La and/or Ln, where contained, and (ii) the amount-of-substance fractions of copper is 0.0182 or more, preferably 0.0182 to 0.127.
  • the concentration of the sum of yttrium, lanthanum or lanthanoid ions is preferably 0.014 mol/l or more, it is preferably in the range of from 0.014 mol/l to 0.35 mol/l, and in particular in the range of from 0.024 to 0.098 mol/l.
  • the sequence of solution of the components is decisive for the rapid preparation of the electrolyte: first of all, the aqueous sulphuric acid is put in, then the copper(II) compound is dissolved and optionally insoluble constituents are separated off in the case that oxides/carbonates of the copper are used. Then, the compound(s) of Y, La and/or Ln used are dissolved.
  • the carbonates and the lanthanum oxides/lanthanoid oxides must always be added with thorough stirring and in partial portions appropriate to the batch size in order to rule out excessive foaming or spattering of the forming electrolyte solution through the carbon dioxide released or otherwise occurring local overheating [La(III) and Ln(III) oxides react highly exothermically with acids].
  • the incorporation of the rare earth elements (Y, La and/or Ln) added as conducting salts into the copper layer was found as an additional effect in the deposition from the acidic copper(II) REE sulphate treatment liquids. While the diamagnetic REE(III) ions of the yttrium and the lanthanum are incorporated only loosely bound, the paramagnetic Ln(III) ions of neodymium, gadolinium or dysprosium for example are incorporated firmly anchored into the copper layer at the same concentration in the treatment liquid. This is shown in Table 2.
  • the structuring of the deposited layer and the incorporation of the REE metals in the copper layer not only depend in a causal way on the magnetic properties of the REE(III) ions but the solubility gradient of the sulphatometallates Cu 3 [REE(SO 4 ) 3 ] 2 has a significant influence in the transition from the comparatively readily soluble copper salts to the less soluble acids H 3 [REE(SO 4 ) 3 ] (cathodic process). Since the solubility of the sulphates increases significantly after neodymium, the effect of the heavy REE ions on the deposition process decreases.
  • the treatment liquid can contain further control additives and additives which influence the viscosity, thermal conductivity, electrical conductivity and/or the deposition of the metal aggregates.
  • the treatment liquid can comprise an additive of the general formula (I):
  • C 1-4 -alkyl is methyl, ethyl, n-propyl, iso-propyl, n-butyl, iso-butyl or sec-butyl, preferably methyl, ethyl, n-propyl, or n-butyl.
  • the additive of formula (I) is a compound of formula (II):
  • the additive is a compound of formula (I), in which:
  • the additive is a compound of formula (III):
  • a particularly preferred additive of the general formula (I) which can be used in the treatment liquid in the method according to the invention is 1,8-dihydroxy-3,6-dithiaoctane (DTO).
  • the additives of formula (I) are commercially available or can be obtained through known chemical synthesis methods or analogously to the latter.
  • additives can be used to influence the surface tension and the dissolution rate of the finest gas bubbles:
  • the possible surface-active substances are added individually or as a mixture, wherein the total concentration in the electrolyte must always lie below the saturation limit, as a rule below 0.05 wt.-%.
  • the use of the terminally-etherified polyethoxylates which are less sensitive to oxidation on the anode is advantageous.
  • the method according to the invention is carried out according to the neutral conductor principle, i.e. the flat metal workpiece is contacted neither cathodically nor anodically but is polarized anodically (positively) by at least one cathode and is then polarized cathodically (negatively) by at least one anode.
  • the current is transferred to the flat metal workpiece not by direct contacting of the flat metal workpiece via a contact element (e.g. a current roll) connected to a current source, but through the treatment liquid.
  • a contact element e.g. a current roll
  • an anodic dissolving or erosion process is induced on a surface of the flat metal workpiece in which tiny particles and residues or impurities located on the surface of the metal foil are removed, whereby a clean surface is obtained. Furthermore, the topographical features of the metal surface, in particular the roughness peaks, are leveled.
  • the anodic polarization or the anodic dissolving process induced thereby leads to an activated surface for the subsequent metal deposition.
  • the surface obtained with the method according to the invention exhibits structural similarity or structural identity with the metal aggregates deposited on the surface of the flat metal workpiece in the subsequent deposition process (epitaxy or syntaxy).
  • the cathodic polarization which follows, a cathodic deposition process is induced, in which a metal or a metal alloy (i.e. several different metals) is deposited on the surface of the flat metal workpiece.
  • the flat metal workpiece used within the framework of the present invention is preferably a metal workpiece with a thickness which is at least 100 times, preferably at least 1,000 times and particularly preferably at least 10,000 times smaller than the length and/or width of the metal workpiece. Consequently, as a rule, the term “surface of the flat metal workpiece” means the area defined by the length and width, not the area defined by the thickness and width or thickness and length.
  • the flat metal workpiece is preferably a metal strip or a metal foil.
  • the term “metal strip” herein refers to a flat metal workpiece with a given width and a thickness of from 100 ⁇ m to 1 mm.
  • metal foil refers to a flat metal workpiece with a given width and a thickness of 100 ⁇ m or less, preferably with a thickness in the range of from 10 ⁇ m to less than 100 ⁇ m.
  • the flat metal workpiece consists entirely of a single metal, in particular of copper, tin, silver or iron. However, it can also consist of a metal alloy, for example of at least two of the named metals, preferably of a copper wrought alloy, iron alloy, silver alloy and tin alloy.
  • a flat metal workpiece made of steel can also be used.
  • the flat metal workpiece is a copper foil, a copper strip, a silver foil, a silver strip, a tin-plated foil or a tin-plated strip, in particular a tin-plated copper foil or a tin-plated copper strip.
  • the flat metal workpiece can also consist of two or more layers of a metal or a metal alloy, wherein the layers can be the same or different. Furthermore, the flat metal workpiece can be formed in such a way that at least one and preferably both surfaces of the flat metal workpiece consist of a metal or a metal alloy and the remaining part of the flat metal workpiece can be made of any material, as long as this is suitable for use in the method according to the invention.
  • the flat metal workpiece Before use in the method according to the invention, the flat metal workpiece is usually pre-treated.
  • Appropriate pre-treatment methods are known in the state of the art and comprise, for example, degreasing, rinsing with water, aqueous surfactant solutions or solvents, and pickling with sulphuric acid.
  • the flat metal workpiece is preferably guided through the treatment liquid and past the at least one cathode and the at least one anode. This is carried out in such a way that the described anodic polarization and cathodic polarization and the anodic dissolving process and cathodic deposition process thereby induced take place.
  • these are usually guided through the treatment liquid using guiding elements (e.g. guide rollers). If a continuous foil installation is used to carry out the method according to the invention, several electrolysis baths (electrolytic cells) can also be connected in series.
  • the at least one cathode and the at least one anode are conceivable.
  • 1, 2, 3, 4 or more cathodes and 1, 2, 3, 4 or more anodes can be used per electrolytic cell or electrolyte bath.
  • These can be arranged differently (e.g. alternately cathode and anode, first all cathodes and then all anodes, several cathodes alternating with several anodes, cathodes and anodes arranged only on one side of the flat metal workpiece or on both sides, etc.).
  • At least one cathode pair and at least one anode pair are preferably 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 such that the flat metal workpiece is located between the two anodes and between the two cathodes.
  • Anodic or cathodic polarization consequently occurs on both sides of the flat metal workpiece.
  • Such a configuration permits the two-sided modification of the flat metal workpiece with deposited metal aggregates.
  • the flat metal workpiece is first of all anodically polarized by two cathodes which are arranged on the same side of the flat metal workpiece and then cathodically polarized by two anodes which are both arranged on the same side of the flat metal workpiece as the cathodes.
  • a separate rectifier is necessary for each side of the substrate (electrode pair).
  • 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.
  • the cycle “anodic polarization/cathodic polarization” is run through several times.
  • the flat metal workpiece can be polarized one or more times anodically and one or more times cathodically in any sequence, wherein typically the anodic dissolving process predominates first and then the cathodic deposition process predominates.
  • a phase with a dominating dissolving process can be interrupted by a short phase with the deposition process (dominating dissolving process, interrupted by deposition process) and vice versa (dominating deposition process, interrupted by dissolving process).
  • the one or more anodic polarizations and the one or more cathodic polarizations can, as already mentioned above, be achieved using a corresponding number of spatially separated anodes and cathodes. However, it is also possible to use electrodes which are connected (contacted) optionally positively or negatively and consequently function both as cathode and as anode.
  • the cathodes and anodes are operated with direct current or a pulsed current, usually a pulsed direct current. Rectifiers can be used for this. If the number of electrodes exceeds two (i.e. more than one cathode and/or more than one anode), the additional electrodes are preferably operated through an additional rectifier. Within the framework of the present invention it is also possible for each electrode to be supplied by another rectifier in at least one operating region (cathodic, anodic), while in another operating region several rectifiers can be connected to one electrode.
  • Insoluble or soluble anodes can be used as anodes in the method according to the invention.
  • the insoluble anodes typically consist of an inert material (or oxides thereof), such as, for example, lead, graphite, titanium, platinum and/or iridium (and/or oxides thereof).
  • Preferred insoluble anodes are made of titanium coated with platinum or iridium and/or ruthenium (and/or oxides thereof).
  • a titanium anode coated with iridium or iridium oxide is particularly preferred.
  • the soluble anodes consist of the metal to be coated or the metal alloys to be coated. Examples of suitable soluble anodes are anodes made of copper or tin.
  • Suitable cathodes can consist of the same material as the material of the anodes.
  • a copper cathode can be used, for example, as cathode.
  • copper electrodes are used both as anode and as cathode.
  • the working temperature of the treatment liquid is preferably between 10° C. and 60° C., particularly 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 recirculation of the treatment liquid depends on the current density used in the electrolytic deposition.
  • the recirculation is necessary in order to reduce to a sufficient minimum the thickness of the electric double layer.
  • the recirculation in the electrode chamber can be ensured, for example, by installing one or more pumps.
  • the recirculation serves above all to preserve the functional efficiency of the electrodes and to avoid salt spots on the foil to be treated.
  • the stacking effects occurring already in the currentless state through the sulphatometallates lead to an extreme primary voltage in order even to set the electrolytic process in motion.
  • This primary voltage can be reduced so much by targeted increase in the recirculation at the electrode surfaces and at the material to be treated in conjunction with a well-chosen time gradient of the current density increase that these electrolytes are available for technical use.
  • the necessary recirculation and the current density gradient depend directly on the REE/Cu ratio used and on the actual REE ion in the sulphate electrolyte.
  • Lanthanum(III) ions provide the greatest sensitivity and thus the best possible process adjustment.
  • the following data for the recirculation given in Table 3 relate to an electrolyte volume in the treatment chamber of 50 litres, an electrode-foil distance of 20-30 mm and a width and height of the polarization chamber of 240 mm (H) and 300 mm (W).
  • the circulation delivers 1.2 l/min. over the filtration bypass.
  • At least one cathode and/or at least one anode of the device is designed as flow electrode which comprises an electrode housing with a metal mesh 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 mesh.
  • the electrode housing further comprises an electrolyte feed for introducing an electrolyte and a flow opening out of which the electrolyte which has flowed through from the electrolyte feed between the metal balls to the flow opening exits.
  • the flow opening is arranged such that a sufficient flow takes place through the operating zone, i.e. the space between electrode and flat metal workpiece.
  • the flow opening is usually arranged so that the exiting electrolyte flows past the metal mesh.
  • the flowing past preferably takes place substantially parallel to the metal mesh.
  • the flat metal workpiece treated with the method according to the invention is usually subjected to an after-treatment.
  • Such after-treatment methods are known in the state of the art and comprise, for example, rinsing with water or solvents, passivation, for example with a chromium(VI)-containing solution, and drying.
  • a device for carrying out the method according to the invention, which comprises at least one container for receiving a treatment liquid, at least one cathode arranged in the container and at least one anode arranged in the container, wherein the at least one cathode and the at least one anode are connected to a current source and wherein the flat metal workpiece is not connected to a current source.
  • the electrode housing usually comprises a cover, in order to prevent the metal balls from falling out and to ensure a defined flow of electrolyte through the flow electrode.
  • the cover can be connected detachably, for example with knurled screws, to the electrode housing and furthermore comprise contacts for connecting to a current source.
  • the flow electrode is connected anodically or cathodically to a current source, wherein the metal mesh is usually contacted anodically or cathodically.
  • the electrolyte which has flowed through the metal balls is preferably collected in an electrolyte channel and then supplied to the flow opening.
  • the electrolyte channel and the flow opening are preferably located in the base of the electrode housing.
  • the flow opening is preferably designed as a flow lip which preferably extends over the entire length of the metal mesh in the base of the electrode housing. If a filter nonwoven arranged in front of the metal mesh is used as anode bag, the flow opening is arranged such that the electrolyte exits in front of the filter nonwoven and flows along the latter substantially laminar.
  • the electrode housing can, for example, consist of a plastic, such as polypropylene.
  • the metal balls can consist of the metals named above for the anode and cathode.
  • at least one anode is designed in the form of the flow electrode described above.
  • the metal balls preferably consist of the metal or the metals which are to be deposited on the flat metal workpiece.
  • the metal balls are preferably copper balls.
  • the metal mesh is preferably an expanded metal mesh (expanded metal screen area), in particular a titanium expanded metal.
  • FIG. 1 shows schematically an embodiment of a dissolving/deposition cell 30 for carrying out the method according to the invention for surface treatment of a flat metal workpiece 32 , in this case a metal foil.
  • the dissolving/deposition cell 30 has a trough-like container 31 , open at the top, in which a treatment liquid 36 is located.
  • the dissolving/deposition cell 30 further has a first, second and third guide roller 34 a , 34 b and 34 c and a first working electrode, which consists of two cathodes 40 a and 40 b arranged parallel, and a second working electrode, which consists of two anodes 44 a and 44 b arranged parallel.
  • 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 guide rollers 34 a , 34 c are arranged above the container 31 outside the treatment liquid 36 and above the first and second working electrodes, while the second guide roller is located on the base of the container 31 within the treatment liquid and below the working electrodes.
  • the dissolving/deposition cell 30 has a separating element 48 for reducing blind currents.
  • the flat metal workpiece 32 runs into the treatment liquid 36 via the first guide roller 34 a and through between the two cathodes 40 a , 40 b , with the result that the latter are located in each case on one of the two sides of the flat metal workpiece 32 passing through. Neither the flat metal workpiece 32 nor the first guide roller 34 a is connected to a current source.
  • the region 38 a of the flat metal workpiece 32 located between the two cathodes 40 a , 40 b is positively (anodically) polarized by the two cathodes 40 a , 40 b .
  • the two cathodes 40 a , 40 b define a dissolving region 42 .
  • the flat metal workpiece 32 After passing through the cathodes 40 a , 40 b , i.e. the dissolving region 42 , the flat metal workpiece 32 is guided via the second guide roller 34 b , which likewise is not connected to a current source, between the two anodes 44 a , 44 b , which are located in each case on one of the two sides of the flat metal workpiece 32 and form the second working electrode.
  • a region 38 b of the flat metal workpiece 32 is polarized negatively (cathodically) by the two anodes 44 a , 44 b .
  • the two anodes define a deposition region 46 .
  • the positively charged metal ions of the treatment liquid 36 migrate to the negatively polarized surface of the flat metal workpiece 32 and are deposited in a defined manner on the surface of the flat metal workpiece 32 .
  • the flat metal workpiece 32 runs out of the treatment liquid 36 and over the third guide roller 34 c which is not connected to a current source.
  • a further subject-matter of the present invention is a flat metal workpiece which was produced with the method according to the invention. It was surprisingly found that the method according to the invention leads to the formation of metal aggregates on the surface of the flat metal workpiece, wherein these metal aggregates have the shape of balls covered with vertical lamellae. They differ thereby from the columnar dendrites as are obtained with the usual methods of the state of the art.
  • FIG. 2 shows a dark field picture (Nikon Eclipse ME600 reflected-light microscope with dark-field unit, camera Leica DFC290, lenses 100 ⁇ ; 50 ⁇ ; 20 ⁇ ; 10 ⁇ ; 5 ⁇ ; software Leica Application Suite 2.6.0 R1; magnification 500 times) of a copper foil surface which was modified according to the method of the invention by deposition of La/Cu from sulphuric acid electrolyte with an La concentration of 14.0 g/l, a Cu concentration of 50.3 g/l and an [La]:[Cu] weight ratio of 0.127 (electrolyte 3) in the continuous foil installation described below. At this magnification, the spherical metal aggregates on the copper foil surface are clearly recognizable.
  • FIG. 3 shows an SEM photograph of a copper foil surface treated electrolytically according to the method according to the invention with sulphuric acid neodymium-copper electrolyte with an Nd:Cu weight ratio of 0.032 at a magnification of 10,000 times.
  • the photograph reproduces a section of a spherical metal aggregate on the copper foil surface and makes the lamella structure thereof visible.
  • FIG. 4 shows a dark field picture (Nikon Eclipse ME600 reflected-light microscope with dark-field unit, camera Leica DFC290, lenses 100 ⁇ ; 50 ⁇ ; 20 ⁇ ; 10 ⁇ ; 5 ⁇ ; software Leica Application Suite 2.6.0 R1; magnification 500 times) of a copper foil surface which was modified according to the method of the invention but by deposition of Cu from sulphuric acid electrolyte with a Cu concentration of 7.0 g/l (electrolyte) in the continuous foil installation described below. At this magnification, the columnar metal aggregates on the copper foil surface are clearly recognizable.
  • the average roughness values Ra and Rz determined in accordance with DIN EN ISO 4288:1998, are preferably in the range of from 0.22 to 0.32 ⁇ m and in particular in the range of from 0.24 to 0.28 ⁇ m for Ra, and preferably in the range of from 1.4 to 2.1 ⁇ m and in particular in the range of from 1.6 to 1.9 ⁇ m for Rz.
  • a copper foil has, for example, roughness values of approximately 0.20 ⁇ m for Ra and 1.3 ⁇ m for Rz.
  • the adhesive strength of the metal surface which is obtained through the deposition of aggregates in the form of balls covered with vertical lamellae on a surface of a flat metal workpiece according to the method according to the invention is surprisingly high.
  • the adhesive strength determined in accordance with the 180° peel test described below using an FR-4 epoxy resin and expressed as peel strength in N/mm, preferably lies at or over 1.5 N/mm.
  • the peel strengths are preferably 1.5 to 3.0 N/mm, in particular 1.8 to 3.0 N/mm.
  • the flat metal workpieces according to the invention can be used as substrate for the formation of strong adhesive bonds with a plurality of materials.
  • the metal aggregates on the surface of the flat metal workpiece lead to a strong adhesive bond on pressing or rolling (roll cladding) with the same or another material, on lacquering with or without subsequent curing/crosslinking or on gluing.
  • a plurality of materials come into consideration as adhesion partner for the metal workpiece according to the invention, for example thermoplastics such as PA 66, PI and PET, synthetic resins (epoxides), 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 according to the invention as substrate for the formation of strong adhesive bonds.
  • the flat metal workpieces according to the invention can be used for a plurality of applications.
  • Laminates of copper with PET for the shielding of cables and plug and appliance housings from electromagnetic interferences, in particular in signal transmission, can be named by way of example.
  • the use as electrical conductor in the production of MID (moulded interconnect devices) circuits is to be mentioned. These are circuits which are based on hot stamping of metallic foils on thermoplastic substrates.
  • a further application is as substrate for electrode material in battery technology.
  • the flat metal workpieces according to the invention can also be used in the production of stable connections required in circuit-board technology for the production of copper laminates.
  • the adhesive strength of the metallic conductor on the substrate e.g. FR-4
  • the process steps necessary in the production etching, drilling, pressing
  • the load on the circuit board in the end product itself.
  • Electrolyte 0 for comparison b) pH value determined for a concentration of the electrolyte of 10 g/l All La—Cu electrolytes (Electrolyte 1, 2 and 3) contain traces of in total less than
  • the continuous foil installation used is designed for foils and strips up to a width of 330 mm.
  • the machine has a pay-off reel and a pay-on reel with electronic tension control.
  • the control possibilities comprise current strength of the individual electrode segments, strip tension, strip speed and temperature of the electrolyte.
  • the rectifiers used originate from the company plating electronic, pe86CW-6-424-960-4 type with 4 outputs.
  • the maximum pulse current is 960 A, the maximum constant current is 424 A.
  • the course of the current with respect to time can be defined as the pulse sequence via the associated software.
  • the electrolytic cell of the continuous foil installation used comprises a cathode and an anode for one-sided electrolytic deposition.
  • the cathode and the anode are positioned parallel to the foil run and arranged such that, when the foil passes through, the same side or surface of the metal foil is opposite first the cathode and then the anode. Furthermore, the cathode and the anode are completely surrounded by electrolyte.
  • a plurality of different configurations can be used, for example a double cathode and a double anode for electrolytic deposition on both sides or two cathodes and anodes arranged one after the other.
  • either a three-part convection electrode or a flow electrode are used as electrodes (anode and cathode). These are connected to rectifiers (pe86CW-6-424-960-4 type with 4 outputs from the company plating electronic, maximum pulse current 960 A, maximum constant current 424 A). The course of the current with respect to time can be defined as the pulse sequence via appropriate software. Furthermore, the current strengths of the individual electrodes, the strip speed and tension as well as the electrolyte temperature are controllable.
  • 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, in the following tests all of the electrode segments were connected with the same polarity.
  • the electrode is located in an anode bag made of polypropylene fabric. The necessary flow is produced by means of a B2 rod pump from Lutz (in 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 screen surface made of titanium expanded metal which is packed behind with copper balls.
  • the electrode is located in an anode bag made of PP fabric.
  • the possible flow rate is 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 base of the housing of the electrode housing and is received by an electrolyte channel in the base 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 mesh.
  • the electrolyte reaches the electrolysis bath and from there via an overflow a reservoir, from which the electrolyte is then pumped again into the flow electrode.
  • This electrolysis arrangement was used in order to simulate the change in polarization of the same surface of the flat metal workpiece using little material which is typical for the method according to the invention.
  • the static electrolytic cell comprises a 1,000 ml glass beaker filled with an electrolyte (900 ml).
  • the glass beaker stands on a heated stirrer.
  • the heated stirrer is used to heat the electrolyte, wherein the temperature is constantly checked by a thermal element with a stainless steel sheath and is kept constant to within +/ ⁇ 2° C.
  • the stirring speed is kept at 1,000 rpm and the stirring is transferred to the electrolyte solution by a round magnetic stir bar (PTFE) with dimensions of 40 ⁇ d6.
  • PTFE round magnetic stir bar
  • Electrodes can consist of an inert material or be made of the material of the foil to be treated. Exchange is possible within a few minutes without problems.
  • These electrodes are flat sheets which are immersed parallel to each other and in each case perpendicularly into the electrolyte solution. The one-side, immersed surface area is between 60 mm ⁇ 80 mm and 60 mm ⁇ 100 mm per electrode. In the centre, the plastic plate was provided with an opening of 20 mm ⁇ 80 mm parallel to the inert electrodes, through which opening the flexible foil holder can be introduced into the cell.
  • This foil holder was therefore formed flexible so that the foil, once inserted, can then pass through the entire process, including the pre-treatment and after-treatment steps (e.g. cleaning/rinse/rinse, etching/pickling/rinse/rinse, electrolysis/rinse/rinse, passivation/rinse/DI rinse) in the same holder and only needs to be taken out of the holder after the last rinse for drying.
  • the foil holder consists of two PP frames with a window of 80 mm ⁇ 60 mm, into which the foil is clamped. The clamping screws are manufactured from PA6 plastic.
  • the lower clamping screws serve only to clamp the foil
  • the upper clamping screws serve in addition to produce a releasable press contact with a TiPt expanded metal mesh.
  • This contact point is immersed in the solution, with the result that the foil is completely immersed in the electrolyte and the contact point is blanked off from the field of the cell by the frame of the foil holder.
  • the expanded metal used for the contacting projects upwards out of the cell and is supplied with current via a crocodile clip.
  • a power unit of the Statron type with pre-selectable current strength and display of the corresponding voltage is used for the current supply.
  • a pole-inverter switch is located between the power unit and the electrolytic cell, whereby the polarity of the foil and of the electrodes can be reversed (switched) in any sequence and at any time during the test.
  • An adhesive strip (Tesafilm® Transparent 57404-00002) was placed over the electrolytically treated, dry, cold metal foil surface which had been stored for at least 15 min. and pressed firmly onto the surface with a soft roller. Care was taken that no air bubbles formed between the adhesive tape and the foil surface. After a period of 30 seconds after the adhesive strip had been pressed on, it was gripped at its projection and pulled off from the firmly held metal foil. A pulling speed of 2 to 3 seconds for a length of 8 cm was maintained.
  • the pulled off adhesive strip was then stuck to a white sheet of paper and the colour change caused by metal aggregates which are torn off from the foil surface and remain on the adhesive strip was assessed. Furthermore, it was assessed whether the adhesive layer of the Tesafilm remained either totally or partially on the surface of the metal foil after the pulling off.
  • the peel strength was determined in accordance with DIN EN 60249 on a Zwick BZ2/TN1S model peel device with an Xforce HP 500 N load cell and testXpert 12.3 software. For this, the samples were cut out of a pressed composite sheet and the foil was pulled off or peeled off at an angle of 180°.
  • the pressed composite sheet was produced by pressing the foil with a plastic substrate at a temperature of 160 ⁇ 10° C. under a pressing pressure of 120 ⁇ 5 bar over a period of 60 ⁇ 5 min. The results of the peel test are given in N/mm.
  • a copper foil with a thickness of 0.035 mm and a width of 300 mm in the hard-as-rolled structural state was first subjected to a pre-treatment which comprised the following steps in the stated sequence:
  • the copper foil pre-treated in this way was then surface-modified in the described continuous foil installation using the electrolytes of Table 4 (Electrolyte 0, Electrolyte 1, Electrolyte 2, Electrolyte 3) and with the following method parameters:
  • Pulse sequence 10 ms at 200 A, 10 ms rest,
  • Electrolyte temperature 50 ⁇ 2° C.
  • the surface-modified copper foil was subjected to an after-treatment which comprised the following steps in the stated sequence:
  • the surface-modified foils obtained with Electrolytes 1, 2 and 3 exhibited a uniform distribution of deposited spherical copper aggregates on the foil surface.
  • FIG. 2 shows this on the example of a surface obtained with Electrolyte 3.
  • FIG. 4 the surface with columnar buildups obtained with Electrolyte 0 is shown for comparison.
  • the adhesion between the modified metal foil surface and the adhesive on the adhesive strip is so high that, on pulling the adhesive strip off, the bond between adhesive and plastic carrier breaks and the adhesive layer of the Tesafilm remains on the foil surface.
  • the metal foil modified with Electrolyte 0 Cu electrolyte without La
  • columnar treatment the debonding of the treatment is observed on pulling off the adhesive strip.
  • a copper foil with a thickness of 0.035 mm and a width of 300 mm in the hard-as-rolled structural state was first of all subjected to a pre-treatment which comprised the following steps in the stated sequence:
  • the copper foil pre-treated in this way 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 :
  • the surface-modified copper foil was subjected to an after-treatment which comprised the following steps in the stated sequence:
  • the lanthanum in the treatment electrolyte Electrolyte 1 was replaced by equimolar quantities of yttrium, neodymium, gadolinium or dysprosium and the surface modification was repeated with otherwise identical parameters.
  • the layers deposited using the different electrolytes were analysed by means of ICP-OES from nitric acid solution (Argon-Plasma; Perkin Elmer, Optima 3000DV, axial registration emission; as standards in each case the concentrations of 0.1 mg/l, 1 mg/l and 10 mg/l of the respective RE metal were used). The results are shown in Table 6.

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US15/105,824 2013-12-19 2014-12-18 Method for electrolytic surface modification of flat metal workpieces in copper-sulfate treatment liquid containing sulfate-metallates Abandoned US20160319448A1 (en)

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DE102013022030.0A DE102013022030B4 (de) 2013-12-19 2013-12-19 Verfahren zur elektrolytischen Oberflächenmodifizierung von flächigen Metallwerkstücken in sulfatometallhaltigen Kupfersulfat-Behandlungsflüssigkeiten, flächiges Metallwerkstück und dessen Verwendung
DE102013022030.0 2013-12-19
PCT/EP2014/078569 WO2015091863A1 (de) 2013-12-19 2014-12-18 Verfahren zur elektrolytischen oberflächenmodifizierung von flächigen metallwerkstücken in sulfatometallathaltigen kupfersulfat-behandlungsflüssigkeiten

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US3666636A (en) * 1969-06-19 1972-05-30 Udylite Corp Electrolytic codeposition of fine particles with copper
US4097342A (en) * 1975-05-16 1978-06-27 Alcan Research And Development Limited Electroplating aluminum stock
FR2646174B1 (fr) * 1989-04-25 1992-04-30 Pechiney Aluminium Procede et dispositif de revetement en continu de substrats conducteurs de l'electricite par electrolyse a grande vitesse
AT406385B (de) * 1996-10-25 2000-04-25 Andritz Patentverwaltung Verfahren und vorrichtung zum elektrolytischen beizen von metallischen bändern
DE19951325C2 (de) * 1999-10-20 2003-06-26 Atotech Deutschland Gmbh Verfahren und Vorrichtung zum elektrolytischen Behandeln von elektrisch gegeneinander isolierten, elektrisch leitfähigen Strukturen auf Oberflächen von elektrisch isolierendem Folienmaterial sowie Anwendungen des Verfahrens
JP4799887B2 (ja) * 2005-03-24 2011-10-26 石原薬品株式会社 電気銅メッキ浴、並びに銅メッキ方法
CN101892502B (zh) * 2010-07-27 2012-02-01 华南理工大学 一种铜-铬-钼三元合金镀层及其制备方法

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