EP0690934B1 - Process and device for electrolytic precipitation of metallic layers - Google Patents

Abstract

PCT No. PCT/DE94/01542 Sec. 371 Date Apr. 22, 1996 Sec. 102(e) Date Apr. 22, 1996 PCT Filed Dec. 23, 1994 PCT Pub. No. WO95/18251 PCT Pub. Date Jul. 6, 1995A process and apparatus for electrolytically depositing a uniform metal layer onto a workpiece is provided. The workpiece, for example a circuit board, serves as a cathode. The anode is insoluble and dimensionally stable. Both anode and cathode are immersed in a plating solution contained in an electrolytic container. The solution includes (a) ions of the metal to be deposited on the workpiece, (b) an additive substance for controlling physical-mechanical properties of the metal to be deposited, such as brightness, and (c) an electro-chemically reversible redox couple forming oxidizing compounds when contacting the anode. A metal-ion generator is provided, supplying metal parts of the metal to be deposited onto the workpiece; The plating solution is circulated between the container and the ion generator for maintaining a reaction between the oxidizing compounds and the metal parts for forming metal ions. The plating solution is controllably re-circulated into the container so that a low concentration of the oxidizing compounds is present in the plating solution adjacent to the workpiece.

Description

The invention relates to a method and an apparatus for electrolytic deposition of uniformly thick metal layers, preferably made of copper, with certain physico-mechanical properties Characteristics.

Electrolytic metallization, for example with copper, of at least superficially electrically conductive workpieces has been known for a long time. For this, the ones to be coated Workpieces connected as cathode and together with anodes in contact with the electrolytic deposition solution brought. An electrical current flow is used for the deposition generated between anode and cathode.

Anodes of the metal that are made of are usually used the deposition solution is deposited. In this case the amount of metal deposited in the solution fed again by dissolution at the anodes. in the In the case of copper, the amount deposited and the anodic dissolved quantity for a given charge throughput approximately equal. This procedure is easy to do because at least in the case of copper, only a sporadic measurement and regulation of the metal ion concentrations of the deposition solution is required.

When performing the process with these soluble anodes however, disadvantages have emerged. Should the Thickness of the deposited metal layers on the surface of the workpiece must be very even at all points, so the soluble anodes are only suitable for the stated purpose due to the fact that this changes its shape over time change so that the field line distribution in the electrolytic Bad also changed. Even the use of smaller, for example spherical, metal pieces as anodes in Insoluble metal baskets is only of limited use in solving the problem suitable because the metal parts often interlock wedge and often gaps due to the dissolution process form when slipping in the metal part fill.

There have therefore been several attempts instead of soluble metal anodes insoluble and therefore dimensionally stable To use anodes. For example, come as materials Titanium or stainless steel. By using this Anode materials form gases, such as Oxygen or chlorine during electrolytic deposition, since the anodic metal dissolution no longer takes place. The The resulting gases attack and release the anode materials this gradually on.

In the German patent DD 215 589 B5 is a method for electrolytic metal deposition when in use Insoluble metal anodes described in the deposition solution Reversible electrochemically convertible substances as an additive be given by intensive forced convection with the deposition solution to the anodes of a deposition device transported, there by the electrolysis current electrochemically implemented, after their sales by intensive forced convection led from the anodes into a regeneration room, in the regeneration room on regeneration metal located in it with simultaneous external currentless metal dissolution of the Regeneration metal in its initial state electrochemically reset and in this initial state again using intensive forced convection of the separator be fed. With this procedure, the specified Disadvantages avoided when using insoluble anodes. Instead of the corrosive gases become those of the separation solution added substances oxidized at the anode, so that the anodes not be attacked.

The dissolution of the metal in the regeneration room is independent of the process of metal deposition on the material to be treated. Therefore the concentration of the metal ions to be deposited due to the effective metal surface in the regeneration room and regulated by the flow rate in the circuit. If there is a lack of metal ions, the effective metal surface and / or the flow rate from the deposition space to the regeneration room or with excess metal ions reduced accordingly. So this procedure requires that a high concentration of the reversible electrochemically implementable substance is contained in the deposition solution. This leads to the oxidized compounds of the additives (Redox system) at the cathode can be reduced again, so that the current efficiency is reduced.

In the German patent application DE 31 10 320 A1 a Process for cation reduction through anode-supported Electrolysis of cations in the cathode compartment of a cell, wherein the anode space iron (II) ions as a reducing agent contains and the anodes relative to that of the anodes surrounding anolytes are moved.

In the German patent application DE 31 00 635 A1 a method and an apparatus for completing a plating solution with a metal to be deposited in one Electroplating device described, wherein the galvanically deposited Metal in one in a plating tank electroplated solution and a stock of the to be deposited Metal within an enclosed space is provided in the electroplating tank as it progresses of the electroplating process produced gases together with the electroplating solution headed into the enclosed space and there be applied to the metal supply for its dissolution and then the dissolved metal supply back to the electroplating solution is added in the electroplating container. The device required for performing the method however, it is very complex since, among other things, it is gastight have to be.

The methods mentioned have the disadvantage that the regenerating separation solutions no additive compounds included, but usually for controlling the physical-mechanical Properties of the metal layers to be deposited are needed. These substances are mainly organic substances.

It is only through these additive compounds that the required physico-mechanical layer properties, such as sufficient gloss, high elongation at break and Layer resistance to cracks during solder shock tests. Without adding these compounds, the layers are dark, matt and rough.

In the document DD 261 613 A1 a method for electrolytic copper deposition from acidic electrolytes with dimensionally stable anode using certain additives for the production of copper layers with defined physical-mechanical Properties described, the Deposition electrolyte also the aforementioned electrochemical contains reversibly implementable additives.

It has been found that the quality of such Deposition solutions of deposited metal layers initially meets the requirements, especially with regard to the physical-mechanical properties, according to longer deposition time but layers of poor quality can be obtained even if the substances in the deposition solution their concentration is supplemented by consumption was reduced when separating. From aged separation solutions little ductile copper plating is left, so that such layers on circuit boards in the area of Tear holes when subjected to a solder shock test will. In addition, the metal layer surface then changes disadvantageous in that it becomes dull and rough.

The present invention is therefore based on the problem the disadvantages of the methods and arrangements according to the Avoid prior art and an economical process and the suitable device for electrolytic Deposition of metal layers, in particular of copper, to find, according to the procedure and by means of Device deposited metal layers predetermined physical-mechanical Have properties by using the deposition solution for controlling the metal layer properties Additive compounds are added and the metal layer properties even after a long separation period do not change adversely. Furthermore, the metal layer thickness should at all points on the surface of the material to be treated almost the same and the deposition with high current efficiency to be possible.

The problem is solved by the features of claims 1 and 8. Preferred Embodiments of the invention are in the subclaims specified.

To ensure sufficiently uniform layer thicknesses on the surface of the material to be treated becomes insoluble, dimensionally stable Anodes used. To complement the by deposition spent metal ions, in a preferred application Copper ions, a metal ion generator is used, containing parts of the metal to be deposited are. In addition to the metal ions, the deposition solution contains compounds of an electrochemically reversible redox system. For Regeneration of those depleted by the consumption of metal ions The deposition solution is guided past the anodes, whereby the oxidizing compounds of the redox system are formed. Then the solution is generated by the metal ion generator passed through, the oxidizing compounds with the Metal parts react to form metal ions. At the same time become the oxidizing compounds of the redox system converted into the reduced form. By the formation of the metal ions becomes the total concentration in the separation solution contained metal ion concentration kept constant. The deposition solution comes from the metal ion generator back in contact with the cathodes and anodes standing electrolyte space.

The solution also contains additive compounds for control the physical-mechanical layer properties. For Maintaining the layer properties even after a long time Deposition times from the deposition solution are according to the invention Means are provided with which the concentration of the oxidizing Connections of the redox system in the immediate vicinity the cathode can be minimized, preferably to one Value below about 0.015 mol / liter.

Apparently, the additive compounds through the oxidizing Compounds of the redox system are decomposed. Thereby on the one hand would be the concentration of additive compounds reduce in an uncontrolled manner. Because the concentration determination these compounds are generally very expensive However, the content of the compounds is very sensitive on the physical-mechanical properties of the Layers, only layers could inevitably fluctuating properties are reflected as a sufficiently fast-acting and precise analysis technology for such requirements is not available.

This problem would also be exacerbated by the fact that reaction products in the decomposition of the additive compounds form that adversely change the layer properties, so that after a long period of electrolysis even with maintenance the content of the additive compounds Enrichment of the harmful reaction products only Layers could be deposited, their properties would not meet the requirements.

The inventive agents with which the concentration of oxidizing compounds near the cathode are minimized can be, preferably to a value below about 0.015 mol / liter are shown below:

The total amount of compounds added to the deposition solution of the redox system is such that practically the total amount of the metal ion generator with the deposition solution supplied oxidizing compounds of the redox system to dissolve the metal parts there with formation of metal ions is needed.

The quantity of metal ions supplied by the dissolution must just add that part of the separation solution Deposition is lost. To maintain the metal ion concentration and to completely reduce the Metal ion generator introduced amount of the oxidizing Connections therefore becomes a minimum size of the metal part surface needed in the metal ion generator. This surface can be enlarged upwards, in particular but it does not need to be variable. That is the refill the metal parts in the metal ion generator in any Technical quantities above the minimum quantity mentioned easy to implement.

The spatial distance between the anodes and the metal ion generator must be small, the connections to the flyover the deposition solution flowing to the anodes to the metal ion generator and back in from the metal ion generator the electrolyte compartment briefly. This ensures that the dwell time of the oxidizing compounds in the electrolyte compartment briefly is. Through the rapid transfer of the oxidizing compounds containing deposition solution in the metal ion generator these connections also have a short lifespan until they are in the reduced connections of the redox system being transformed.

In addition, the flow rate of the deposition solution especially when transferring from the anodes to the metal ion generator be as large as possible.

To the concentration of the oxidizing compounds as possible to keep it low, there is also the possibility of another Introduce oxidizing agents directly into the metal ion generator. The is particularly suitable for this purpose Air contains oxygen. When oxygen reacts with the metal parts only water is created, which is the deposition process unaffected.

To introduce air into the metal ion generator are in the lower area of the generator means for blowing in atmospheric oxygen intended.

Another way to complement that is by deposition metal ions removed from the deposition solution basically exist in it, the metal ions in the form of their compounds or add salts to the separation solution. However, in this If the concentration of the inevitably with the anionic proportions added to the metal ions of the compounds or salts by the continuous addition of connections increases continuously so that the Solution must be discarded after a certain time. Becomes in the present case only a small proportion of those to be supplemented Metal ions by adding the appropriate compounds or salts added, the time until discarding the Solution be quite long. By combining the addition of Metal ions by adding the salts with the regeneration of the Solution in the metal ion generator can add the compounds or salts up to a few percent of the supplementary requirement be lowered.

In this case, the possibility of the metal ion concentration is advantageous in the separation solution on control technology easy and quick way to influence.

By the reduction achieved by means of the aforementioned measures the life of the oxidizing formed on the anode Connections of the redox system and the minimization of Concentration of the compounds becomes a possible decomposition of the additive compounds avoided or at least clearly decreased.

The metal ion concentration in the electrolyte space can also be due to a special circulation of the separation solution influence. The reduced ones are in the cathode compartment Connections of the redox system, which on the anodes through the Electrolysis current electrochemically returns to the oxidizing Connections are implemented. The amount of oxidizing Compounds and thus the metal ion concentration can be reduced if only part of the separation solution from the space near the cathode to the anodes and from there into the metal ion generator. The other Part of these do not contain the oxidizing compounds In contrast, solution is directly in the metal ion generator headed. For this there are separate processes for the separation solution, which are located near the cathode. The solution branched off via the processes passes through suitable piping in the metal ion generator.

The surface of the metal to be dissolved is again so plentiful dimensioned that all introduced into the metal ion generator oxidizing compounds electrochemically implemented can be.

This measure makes it easy to control the metal ion concentration in the separation solution and therefore one Automation of the control that is technically easy to implement enables. By regulating the volume flows of the separation solution from the cathode via the anode to the metal ion generator on the one hand and from the cathode directly into the Metal ion generator on the other hand can change the metal ion concentration can be set easily.

The flow rate can also be used for control purposes the separation solution in the circuit and the tension between Cathode and anode can be adjusted.

The flow conditions in the electrolyte compartment are to be designed that on the one hand a flow of the separation solution from the cathode is directed towards the anode and the other is the Initially, however, the deposition solution flows directly onto the cathode becomes. The latter is required to be even Layers with sufficiently high current densities and with specified ones physico-mechanical properties economical to be able to generate. These flows are direct Inflow to the cathode using nozzle sticks or surge nozzles and by subsequently redirecting this flow to the anodes accomplished.

The for carrying out the method according to the invention In addition to the cathodes, the preferred arrangement comprises insoluble, preferably perforated, dimensionally stable anodes, devices to flow onto the cathodes and anodes with the deposition solution (Nozzle sticks, surge nozzles), means for deflecting the Flow to the anodes and connecting lines for transfer the deposition solution flowing to the anode to the metal ion generator as well as to transfer the metal ion generator escaping deposition solution back into the electrolyte compartment. In a preferred embodiment, you can increase the flow velocity when transferring the Deposition solution from the anodes to the metal ion generator too Means for sucking off the separation solution can be provided.

To avoid mixing the parts of the separation solution, which are in the vicinity of the cathode or the anode, the electrolyte compartment can also be separated by ion permeable walls (Ion exchangers, diaphragms) divided into several compartments be.

The metal ion generator is preferably a fillable from above tubular device that in the lower area with a floor and for electrolyte inflow with at least one Pipe socket with side openings and in the upper area with an overflow opening in an electrolyte container is provided. In a particularly favorable embodiment are inclined inside the metal ion generator, preferably perforated plates attached.

The method is preferably suitable for metallization of printed circuit boards. In this case, copper in particular deposited on the surfaces and lateral surfaces of the boreholes.

There can be common diving arrangements in which the circuit boards are immersed in the deposition solution from above be or horizontal systems where the circuit boards recorded horizontally and by suitable means in horizontal Direction through the system.

In addition to copper, which is preferred with the inventive method deposited from the arrangement also claimed can basically be other metals, such as for example nickel, deposited in the manner according to the invention will.

The basic composition of a copper bath can vary within relatively wide limits when using the method according to the invention. An aqueous solution of the following composition is generally used: Copper sulfate (C _u SO ₄ · 5 H ₂ O) 20 - 250 g / liter preferably 80 - 140 g / liter or 180 - 220 g / liter Sulfuric acid, conc. 50 - 350 g / liter preferably 180 - 280 g / liter or 50 - 90 g / liter Iron (II) sulfate (FeSO ₄ · 7 H ₂ O) 0.1 - 50 g / liter preferably 5 - 15 g / liter Chloride ions (added for example as NaCl) 0.01-0.18 g / liter preferably 0.03-0.10 g / liter.

Instead of copper sulfate, you can at least partially other copper salts can be used. Even the sulfuric acid can be partially or entirely by fluoroboric acid, methanesulfonic acid or other acids are replaced. The chloride ions are used as alkali chloride, for example sodium chloride, or in the form of hydrochloric acid, p.A. admitted. The addition of sodium chloride can be omitted in whole or in part if in the Additives already contain halogen ions.

The effective Fe ²⁺ / Fe ³⁺ redox system is formed from iron (II) sulfate heptahydrate. It is ideally suited for the regeneration of copper ions in aqueous acidic copper baths. However, other water-soluble iron salts, in particular iron (III) sulfate nonahydrate, can also be used, provided the salts do not contain any biodegradable (hard) complexing agents in the compound, since the latter cause problems in the rinsing water disposal (for example iron ammonium alum).

In addition to iron salts, other redox systems are compounds of the elements titanium, cerium, vanadium, manganese, chrome and others also suitable. Connections that can be used are in particular Titanyl sulfuric acid, cerium (IV) sulfate, sodium metavanadate, Manganese (II) sulfate and sodium chromate. For special applications are also combinations of the aforementioned redox systems usable.

The method according to the invention can otherwise be used known and proven electrolytic metal deposition Elements are retained. So the separation solution for example, usual brighteners, levelers and wetting agents be added. To copper deposits with predetermined maintain physical-mechanical properties, become at least one water-soluble sulfur compound and added an oxygen-containing, high molecular compound. Additive compounds, such as nitrogen-containing sulfur compounds, polymeric nitrogen compounds and / or polymeric phenazonium compounds can also be used.

The additive compounds are contained in the deposition solution within the following concentration ranges: usual oxygen-containing, high-molecular compounds 0.005 - 20 g / liter preferably 0.01 - 5 g / liter usual water soluble organic sulfur compounds 0.0005 - 0.4 g / liter preferably 0.001 - 0.15 g / liter

Thiourea derivatives and / or polymeric phenazonium compounds and / or polymeric nitrogen compounds as additive compounds are used in the following concentrations: 0.0001 - 0.50 g / liter preferably 0.0005 - 0.04 g / liter

To form the deposition solution, the additive compounds are added to the basic composition given above. The conditions for copper deposition are given below: PH value: <1 Temperature: 15 ° C - 50 ° C preferably 25 ° C - 40 ° C cathodic current density: 0.5 - 12 A / dm ² preferably 3 - 7 A / dm ² Some oxygen-containing, high-molecular compounds are listed in Table 1 below: (Oxygenated high molecular compounds) Carboxymethyl cellulose Nonylphenol polyglycol ether Octanediol bis (polyalkylene glycol ether) Octanol polyalkylene glycol ether Oleic acid polyglycol ester Polyethylene propylene glycol + polyethylene glycol Polyethylene glycol dimethyl ether Polyoxypropylene glycol Polypropylene glycol Polyvinyl alcohol Stearic acid polyglycol ester Stearyl alcohol polyglycol ether β-naphthol polyglycol ether (Sulfur compounds) 3- (benzothiazolyl-2-thio) propyl sulfonic acid, sodium salt 3-mercaptopropan-1-sulfonic acid, sodium salt Ethylene dithiodipropyl sulfonic acid, sodium salt Bis (p-sulfophenyl) disulfide, disodium salt Bis (ω-sulfobutyl) disulfide, disodium salt Bis (ω-sulfohydroxypropyl) disulfide, disodium salt Bis- (ω-sulfopropyl) disulfide, disodium salt Bis (ω-sulfopropyl) sulfide, disodium salt Methyl (ω-sulfopropyl) disulfide, disodium salt Methyl (ω-sulfopropyl) trisulfide, disodium salt O-ethyl-dithiocarbonic acid S- (ω-sulfopropyl) ester, potassium salt Thioglycolic acid Thiophosphoric acid-O-ethyl-bis- (ω-sulfopropyl) ester, disodium salting over Thiophosphoric acid tris (ω-sulfopropyl) ester, trisodium salt

In Table 2 above are some sulfur compounds with suitable functional groups to generate the Water solubility listed.

The separation solution becomes by blowing air into the electrolyte space emotional. By additional flow to the anode and / or the cathode with air, the convection in the area of the respective surfaces increased. This is the mass transfer optimized near the cathode or anode, so that greater current densities can be achieved. If necessary, in small amount of aggressive oxidizing agents, such as for example oxygen and chlorine, are thereby by the Anodes dissipated. Also a movement of the anodes and cathodes causes an improved mass transfer to the respective Surfaces. This ensures a constant diffusion controlled Deposition achieved. The movements can be horizontal, vertically, with even lateral movement and / or through Vibration occur. A combination with the air flow is particularly effective.

Inert material is used for the anodes. Anode materials that are chemically and electrochemically stable with respect to the deposition solution and the redox system used are suitable, for example titanium or tantalum as the base material, coated with platinum, iridium, ruthenium or their oxides or mixed oxides. Titanium anodes with an iridium oxide surface, which was irradiated with spherical bodies and thereby compacted without pores, were sufficiently stable and therefore had a long service life. The amount of aggressive reaction products formed at the anode is determined by the anodic current density or the anode potential regulated by the voltage between cathode and anode. Below 2 A / dm ² , their formation rate is very small. In order not to exceed this value, large effective anode surfaces are sought. Therefore, perforated anodes, for example anode meshes or expanded metal, with a corresponding coating are preferably used in the case of limited spatial dimensions. This combines the advantage of the large effective surface area with the simultaneous possibility of intensive flow through the anodes with the deposition solution, so that any aggressive reaction products that may arise can be removed. Anode nets and / or expanded metal can also be used in several layers. This increases the effective surface area accordingly, so that the anodic current density is reduced for a given electroplating current.

Metal is in a separate container, the metal ion generator, which is traversed by the separation solution. The metal ion generator is in the case of Copper deposition of metallic copper parts, for example in Form of pieces, balls or pellets. That for regeneration Metallic copper does not need phosphorus contain, but also does not interfere with phosphorus. With the conventional The composition is the use of soluble copper anodes of the anode material, however, of great importance: In in this case the copper anodes must contain about 0.05% phosphorus. Such materials are expensive, and the addition of phosphorus causes residues in the electrolytic cell that are to be removed by additional filtering.

Since according to the inventive method also metallic copper parts Can be used with no additives usually contains electrolytic copper, including copper scrap, used. An interesting variant exists in that the copper-coated PCB waste, how they are produced in large quantities in the production of printed circuit boards, can also be used for this, provided that does not contain other metals. This waste, consisting from the polymeric base material and the applied copper layers, are because of the adhesive bond between the both materials in a conventional manner only at high costs disposable. After the beneficial dissolution of the copper this waste in a suitable metal ion generator sorting of the base material is possible. Similarly, reject boards can also be used be used.

In the circuit of the separation solution can also Filters for separating mechanical and / or chemical residues be inserted. However, their needs are in comparison to electrolytic cells with soluble anodes less, because of the addition of phosphorus to the anodes Anode sludge does not arise.

Fig. 1 - Prinzip einer Vorrichtung zur Tauchbehandlung,

Fig. 2 - Prinzip einer Vorrichtung ohne und mit Diaphragma,

Fig. 3 - Prinzip einer Vorrichtung mit serieller Führung der Abscheidelösung,

Fig. 4 - Prinzip einer Vorrichtung mit horizontalem Transport des Behandlungsgutes,

Fig. 5 - Metallionen-Generator an einer Vorrichtung zur Tauchbehandlung,

Fig. 6 - Metallionen-Generator an einer Vorrichtung zum horizontalem Transport des Behandlungsgutes.

The following schematic figures serve to further explain the invention and further preferred embodiments.

1 - principle of a device for immersion treatment,

2 - principle of a device without and with a diaphragm,

3 - principle of a device with serial guidance of the separation solution,

4 - principle of a device with horizontal transport of the material to be treated,

5 - metal ion generator on a device for immersion treatment,

Fig. 6 - metal ion generator on a device for the horizontal transport of the material to be treated.

In Fig. 1, the inventive method is based on a schematic device shown. The electrolyte room 1 is in the container 3. The metal ion generator 2 is constructed and arranged with respect to the container 3 that short distances when feeding the separation solution from the Anodes 5 to the metal ion generator and back from there result in the electrolyte space. This is why the metal ion generator in the present case shown in two parts and each located near the insoluble anodes. However, this division into two is not mandatory. So can for example as a one-piece unit on the side or be arranged below the bath tank. The ones to be resolved Copper parts 8 are in bulk in the metal ion generator introduced to allow easy passage of the To enable separation by the generator. In this on the other hand, however, a minimum loading with copper parts not fall below. The pump 11 promotes the Separation solution in the circuit through the arrangement. Essential is that the treatment material 6 connected as cathode, such as indicated by the arrows 14, with that enriched with copper ions Separation solution via nozzle assemblies or surge nozzles, which are not shown here. Thereby it is achieved that the copper layers on the surfaces of the material to be treated with the required quality and Speed to be deposited. Furthermore arises within of the electrolyte space is another flow of which in the vicinity of the material to be treated 15 in the direction to the rooms near the anodes 16. Die deposition solution flowed to the anodes passes through them if the anodes are perforated, and passes with the progressive flow in the drain 4, the leads into the metal ion generator. This ensures that a transport of anodically formed oxidizing compounds of the redox system (iron (III) ions) into the cathode compartment 15 is minimized. This in turn reduces the harmful decomposition of the additive compounds with simultaneous Increasing the cathodic current efficiency.

Along the transport route from the anodes to the drain in the metal ion generator becomes the additive compounds probably through a chemical degradation reaction involving decomposes the oxidizing compounds of the redox system. Therefore, one outside of the electrolyte space 1 is as possible short connection with high flow velocity the separation solution to the metal ion generator.

The minimum loading of the metal ion generator with copper parts ensures that the oxidizing compounds formed fully implemented within the metal ion generator and the concentration of these compounds on Output of the metal ion generator to a value of approximately Be reduced to zero. This means that with the separation solution contacting copper surface in the metal ion generator for complete reduction of the oxidizing Connections to the reduced compounds (iron (II) ions) with simultaneous external currentless dissolution of copper leads to the formation of copper ions. The reduced connections of the redox system do not contribute to the decomposition of the additive compounds at.

• niedrige anodische Stromdichte
• inerter Anodengrundwerkstoff
• inerte Anodenbeschichtung
• Anodenoberflächenverdichtung
• flüssigkeitsdurchlässige Anodengeometrie.

By targeted flow to the cathode surfaces, the anodes are subject to less electrolyte exchange for a given total circulation capacity. As a result, the aggressive gases that may develop at the anodes are removed correspondingly more slowly, so that the corrosion of the anodes increases on the one hand, but is limited on the other hand by the following measures:

• low anodic current density
• inert anode base material
• inert anode coating
• Anode surface compaction
• liquid-permeable anode geometry.

These measures ensure that the additive compounds, to control the physico-chemical properties of the metal layer be added to the separation solution, also in arrangements with insoluble dimensionally stable anodes can be used. Special mixtures of additive compounds are not necessary for this. It will be high cathodic current efficiency and a long service life of the insoluble Anodes reached.

A further device according to the invention is shown in FIG. On the one hand, this differs from the arrangement according to Figure 1 by a modified management of the separation solution inside the electrolyte space that comes from one in the Area 15 of the material to be treated, the cathode area, and the spaces 16 in the vicinity of the anodes, the anode compartments. These spaces are in the graphic Representation separated by dashed lines 17. The deposition solution in the metal ion generator 2 at Reduction of Fe (III) - to Fe (II) ions enriched with copper ions flows into each room separately and arrives by nozzle sticks or surge nozzles, not shown, accordingly the arrows 12 and 14 to the anodes 5 and the cathodic material to be treated 6. A mixing of the deposition solution in the anode compartment 16 with that in the cathode compartment 15 can only take place on a small scale, especially because the deposition solution from the anode compartment via own processes 4 can drain off and separate the separating solution in the cathode compartment Has 18. In this embodiment, the Fe (III) - Ion concentration in the cathode compartment kept low, the immediate connected to the inlet to the metal ion generator 2 is, so that a short guide path from the anode compartment to Metal ion generator results. In contrast, the transport routes from the cathode compartment via the outlet 18 to the generators be long since there are no harmful interactions between the reduced compound that is in the cathode compartment deposition solution is contained, and the additive compounds consists. To avoid even a minor one Electrolyte mixing of the deposition solutions in the cathode and in the anode compartment, these compartments can be taken along lines 17 through an ion-permeable partition (diaphragm), which in turn not chemically changed by the deposition solution will be separated. The partitions are only one small dimensions or not at all for the deposition solution permeable, so that it may only be a slow one Compensation of different hydrostatic pressures in the Allow rooms 15 and 16. For example, are suitable Polypropylene fabric or other membranes with a permeability for metal ions and their corresponding counterions (for example Nafion from DuPont de Nemours, Inc., Wilmington, Del., USA). By separating the rooms with partitions it is ensured that the separation solution, for example by swirling not from the anode to the cathode compartment can reach. This measure leads equally a further decrease in the concentration of oxidizing Redox system connections near the cathode. Therefore These measures also result in advantageous effects with regard to the aging resistance of the deposition solution.

The deposition solution in the anode compartment, the one there formed Fe (III) ions, is again on the shortest Paths transferred into the metal ion generator and under there Formation of the Fe (II) ions enriched with copper again. in the practical operation is a state of equilibrium between the copper dissolution in the metal ion generator and the copper deposition set on the item to be treated.

A further embodiment of the invention is shown in FIG shown a two-part metal ion generator. The in Metal ion generator 2 deposition solution enriched with copper ions is only introduced into the cathode compartment 15. This solution also contains only Fe (II) ions and none Fe (III) ions. The deposition solution becomes serial from the cathode compartment 15 passed to the anode compartment 16. The one in the metal ion generator Fe (II) ions formed therefore reach the Passing through the cathode compartment with the deposition solution via a pump 19 into the anode compartment. The supply of the separation solution is in the cathode compartment via another pump 11 accomplished. A hydrodynamic is advantageous Constancy and the resulting constant transport conditions for the electrochemically active additives of the redox system.

Furthermore, this serial guidance of the separation solution allows a division of those withdrawn from the cathode compartment Separation solution. To regulate the concentration of copper ions in electrolyte room 1, comprising the cathode and anode rooms, part of the solution is shown in dashed lines Lines 43 passed directly into the metal ion generator. This subset contains almost no oxidizing agents Connections of the redox system, so that by admixing this Portion in the solution stream coming in from the anode compartment the metal ion generator is initiated, the copper dissolution rate is reduced. By control and / or regulation of the subsets of the two streams by not shown three-way valves can thus the copper ion concentration adjust in the separation solution. In the in Figure 2 arrangement shows these possibilities not used, although two separate processes 4 and 18 for the deposition solutions from the cathode and anode area available. The solutions of both rooms are brought together there and passed together into the metal ion generators. The regenerated emerging from the metal ion generators Solutions are supplied to rooms 15 and 16. The procedure according to FIG. 3 is advantageous if the deposition solutions of the anode and cathode compartments in the electrolyte compartment cannot be mixed in processes 4 and 18 a complete one from the anode and cathode compartments However, separation of the running solutions is not guaranteed is.

In Figures 1 to 3 is the introduction of copper ions enriched separation solution in the container 3 as an example shown from below and in the metal ion generator 2 from above. The discharges through processes 4 are correspondingly and 18 from container 3 above and from the metal ion generator 2 shown below. Separation solution cycles in other directions are also possible, such as the initiation of the solution into the metal ion generator from below.

Another embodiment of the invention, in particular for electrolytic metallization of plate-like items to be treated, preferably of printed circuit boards, horizontally Pass through the arrangement is shown in Figure 4. The plant shown in sections in the side view from the electrolytic part 20 and one below shown metal ion generator 21 with copper filling. The electrolytic part 20 consists of several electrolytic Single cells. Four of these individual cells are shown in FIG. 4 with the reference numerals 22, 40, 41, 42 shown, namely each with an insoluble anode 23 for the top and for the underside of the item to be treated 24. The item to be treated is electrical with a rectifier, not shown connected and polarized cathodically. It is in Direction of arrow 25 guided by rollers or disks 26 transported through the plant. The transport elements 26 are located is evenly distributed along the entire system. For the sake of simplifying the illustration, these are here reproduced only at the beginning and at the end of the transport route. There are also in the electrolytic cells evenly distributed surge nozzles or flood pipes 27, 39. This correspond to the nozzle sticks already mentioned.

The flood pipes 27, 39 is 28 separation solution via the pipes coming from the metal ion generator 21 by means of Pumps 29 supplied fed. Through the outlet openings the separator solution flows onto the flood pipes or surge nozzles the surfaces of the material to be treated 24. Thereby copper ions reduced to metallic copper and on the material to be treated deposited as a metallic layer, and the Iron (II) ions that are also present are mixed with the effluent Electrolytes promoted towards the anodes 23. To avoid backflow from the anodes to the cathodes Various measures are planned, their implementation is shown schematically in Figure 4. The one with copper enriched separation solution becomes the flow of the Cathode (material to be treated) used. From the plate-shaped material to be treated the solution flow is then redirected so that it, as indicated by the arrows 30, in the direction the anodes move. In the case of the preferred ones perforated anodes, the solution passes through them and then passes through suction pipes 31 and pipes 32 back into the metal ion generator. The anodes can, for example consist of expanded metal or nets. Culverts 33 support the flow-through process. To avoid Vortex formation can on the intake manifolds 34, the extend in the direction of the material to be treated, attached will. The remaining gap 35 between the guide walls and the material to be treated can be a few millimeters. This forms From a fluidic point of view, almost closed electrolytic Cells with favorable flow conditions. Also the flood pipes 27 can be provided with guide walls 36 prevent further possible turbulence.

In the electrolytic cells of the arrangement in Figure 4 are examples of different flood pipes in different numbers shown. The cycle of the separation solution is like this led that in the electrolytic part of the plant Level 37 sets, which is above the intake manifolds. In the Electrolytic cell 42 shown on the right are each Partitions 38 between the anodes 23 and the material to be treated 24 drawn. This will replace the separation solutions directly minimized in the cathode and anode compartment. By using ion-permeable partitions on the other hand enables an ion exchange between the chambers. The solution in the cathode compartment can escape from the front. Additional flood tubes 39 are provided in the anode compartment. The solution this chamber exits through the suction pipes 31. For one such a cell is in turn suitable for serial flow control, as has already been described with reference to FIG. 3.

The derivation of the deposition solution from the anode compartment via the Intake pipes 31 in the metal ion generator 21 can be on the shortest Ways are made to determine the lifespan of the iron (III) ions to keep it as low as possible. Hence the metal ion generator 21 here as close as possible to the electrolytic Part 20 arranged. This results in short connection paths and short transport times. The construction principle can advantageously be chosen so that the parts 20th and 21 form an overall system. Several flood pipes 27 are each fed by a pump 29, as shown in FIG 4 is shown. But it can also be a single pump be used. This would result in longer communication routes between the flood tubes 27, 39 and the metal ion generator 21 lead. The separation solution in these connecting lines contains practically no oxidizing compounds of the redox system. The protection of the additive compounds is therefore also in guaranteed this area.

The electroplating system is shown in FIG. 4 in a side view. The parts shown (anodes, tubes) are elongated into the depth of the drawing, i.e. across the Direction of transport over the material to be treated. The one in the electrical Field between the anode and cathode parts, such as for example, the flood pipes 27 are made of electrical non-conductive plastic. Your electrical anti-glare is not annoying here because the material to be treated is slowly moving moved through the plant and thus continuously the different is exposed to electrical fields.

In Figure 5 is an inventive arrangement with two metal ion generators 44, an electrolyte room 1 and two more Electrolyte containers 45 shown. This arrangement will operated in the immersion process. The cell is in this case Electroplating the front and back of the material to be treated 6 symmetrical. The two shown in the figure Metal ion generators 44 and the electrolyte containers 45 can also be provided individually and in this Case assigned to both sides of the material to be treated.

The metal ion generator 44 consists of one round tubular body 46 with an upper opening 47. All for this The materials used are resistant to the deposition solution and the additives contained in the solution. At least protrudes through the bottom 48 of the metal ion generator a pipe socket 49 into the interior of the metal ion generator inside. This pipe socket has side openings 50. This form a sieve, which on the one hand penetrates metallic Prevents copper in the piping system and to others the passage of the deposition solution into the metal ion generator allowed. A small protruding roof closes the pipe socket upwards. The roof holds at the same time the side openings 50 are free of fine copper granules, which is in this area of the metal ion generator. There is a mixing and collecting chamber below the floor 51. It contains copper particles and impurities, that could pass through the sieve. After Opening the base plate 52 is the chamber for cleaning purposes accessible. During operation, it flows out of the anode compartment 16 pumped-out deposition solution containing copper-dissolving Fe (III) ions is enriched. In addition, air can also contains oxidizing oxygen, via lines 56 in the Metal ion generator to be blown in. In this case the chamber 51 also serves as a mixing chamber. Through the holes 50 of the pipe socket 49 reaches the separation solution and optionally air into the interior of the metal ion generator. The lower part of the generator is predominantly fine copper granulate, which is obtained by dissolving the metallic Copper was created. It has a very large specific Surface, which is the inflow and with Fe (III) ions enriched deposition solution immediately for copper dissolution offers. The Fe (III) ions therefore quickly become Fe (II) ions reduced with simultaneous dissolution of copper. Inside the metal ion generator the amount increases the Fe (III) ions rapidly decrease towards the top. This causes the electrolyte copper introduced as granules or sections 53 upwards to an ever smaller extent becomes. The dimensions of the granules remain in the upper range of the metal ion generator large. This also leaves the permeability received for the deposition solution. Through the overflow 54 the solution runs from the metal ion generator without pressure into the electrolyte tank 45. Inside the metal ion generator the overflow 54 bends downwards in such a way that from the top sliding copper granules 53 not for constipation of the generator can lead. As a result of each other coordinated enough large dwell time in the generator flowed in separation solution and at the same time sufficiently large The copper surface offered for dissolution contains the Separation solution, which overflow 54 in the electrolyte tank 45 flows, practically no more Fe (III) ions. A such oversizing of the regeneration unit thus certain that the attack of the Fe (III) ions on the additive compounds the separation solution already in the middle range of the generator has ended.

The filling and refilling of the metal ion generator with Metallic copper 53 takes place from above through, for example funnel-shaped opening 47. This can be with a lid be closed. The area above the overflow 54, because there is no separation solution, it is used for storage of metallic copper in the metal ion generator to be resolved. The filling and refilling can done manually. The arrangement is due to the lack of pressure at the filling opening 47 and the vertical or oblique Installation excellent for automation of the filling process suitable. This can be continuous or discontinuous happen. Known from conveyor technology, not here Transport the illustrated conveyor belts or vibratory conveyors the metallic copper in the openings 47 of the generators.

The advantage of the invention is that in the metal ion generator Copper parts of different geometric shapes dissolved can be. Different shapes have different ones Bulk behavior. To maintain the Permeability of the bed for the separation solution and for Ensuring a sufficiently large and accessible solution Copper surface are additional individual Measures possible:

Downwardly sloping plates 55 inside the generator prevent excessive compression of the copper in the lower Area. The plates are provided with openings, whose Dimensions of the size of the filled metallic copper parts is adjusted. The breakthroughs are going from plate to Plate according to the copper resolution from top to bottom chosen smaller. Likewise, the dimensions of the plates increase from top to bottom. The angles of the inclinations can also be adapted to the conditions in the Adjust the metal ion generator filled copper pieces.

The inclination of the metal ion generator itself can do that effect the same. Through the air injection 56 in the lower Area of the metal ion generator or in the mixing and Collection chamber 51 also becomes a copper-dissolving substance, in this case oxygen. It also increases the associated swirling of the copper granules in the metal ion generator the reduction of Fe (III) ions and the copper resolution. At the same time, the permeability for the deposition solution increased by the copper parts. At mutually interlocking copper fillings it can be useful be the metal ion generator temporarily or permanently to shake. The shaking motion can preferably be from one Vibratory conveyor, with the automatic filling concerned is derived. All of the above Measures for trouble-free continuous operation of the metal ion generator can also be combined with each other.

The electrolyte containers shown in Figures 5 and 6 45, 67 serve the dependence of the flow of the separation solution to the material to be treated 6, 69 by the flow by the metal ion generator 44, 66. This has the advantage that the amount of separation solution in both circuits and their speed individually adjustable are. These processes are described below with reference to FIG. 5 described.

The separation solution is removed from the electrolyte container by means of a pump 57 45 promoted in the electrolyte room 1. By the flood pipes 58 arranged there flow the solution to the Treatment material 6 and from the flood pipes 59 to the liquid-permeable insoluble anodes 5. The division of the Solution flow to the flood pipes 58 and 59 takes place through here adjustable valves, not shown. From the cathode compartment 15, the separation solution flows through the outlet 18 through pipes 60 and the outlet 61 back into the electrolyte container 45 back. Are located just behind the anodes 5 Suction pipes 62 through which the pump 63 uses Fe (III) ions enriched separation solution suctioned off and with high Speed is promoted in the metal ion generator. From there the Fe (II) and Cu (II) ions enriched The solution is then returned to the electrolyte container 45.

The distribution of the streams on the flood pipes 58 and 59 becomes as follows set that there is an excess in the cathode chamber 15. This balances out towards the anode compartment 16. Are the both rooms by a partition 17, as shown in Figure 5, separated, so ensures at least one opening 64 in the Partition for ensuring that the separation solutions in both rooms can take place in the direction of the arrow. To avoid a mixing of the solutions in electrolyte room 1 and convective transport of Fe (III) ions from the anode to the Accordingly, the cathode compartment can only be ensured that a higher hydrostatic pressure in the deposition solution in the cathode compartment 15 compared to that in the anode compartment 16. This with a corresponding setting of the partial flows through the flood tube 58 and through the flood tubes 59 of the circuit the pump 57 ensured. In addition, the Circuits of pumps 57 and 63 are independent of one another.

In the metal ion generator all are introduced with the flow Fe (III) - reduced to Fe (II) ions. Still can it cannot be ruled out that a very small, barely measurable Number of Fe (III) ions passes the metal ion generator and gets into the electrolyte container 45. To in this Containers that have passed Fe (III) ions to reduce Fe (II) ions copper parts 65 are also placed in this container. This can also be copper scrap.

Another embodiment of the device according to the invention to carry out the method is shown in Figure 6. This is one shown in cross section horizontal circuit board electroplating system. In the Figure is the metal ion generator 66, an electrolyte tank and a plating cell 68 is shown. The one to be metallized PCB 69 is in the arrangement of brackets 70 gripped and conveyed horizontally through the plant. The Contacting the circuit board with the negative pole of one is not Rectifier shown is also done via this Parentheses. In another embodiment, the contacting could also done via contact wheels. A pump 71 delivers the separation solution via flood pipes 72, 73 to the printed circuit boards and to the insoluble perforated anodes 74. Via Processes 75 is the deposition solution from the cathode compartment in the electrolyte container 67 is returned. From the anode room Pump 86 conveys the deposition solution enriched with Fe (III) ions through suction pipes 76 at high speed the metal ion generator. A flow 77 for level control is designed as an overflow, ensures that excess Separation solution from the upper area of the anode compartment also in the circuit to the metal ion generator 66 and does not get into the electrolyte container 67. The metal ion generator is constructed as described using FIG. 5 has been. The separation solution passes through the overflow 78 back into the electrolyte container 67. Also in this are copper parts 79, which are a reduction of in this area there may be stray Fe (III) ions to Fe (II) ions. Partitions 80 are also provided provided between the anode and cathode spaces. openings 81 in these partitions also provide a balance here the flows of the deposition solution from the cathode to the anode compartment. These flow directions are also set when there are no partitions.

Horizontal working lines, as in the figures 4 and 6, and vertical electroplating equipment have dimensions of several meters in length of the electrolytic Cells. Therefore, in practice, preferably several Metal ion generators arranged along the plant. This allows them to be installed in close proximity to the electrolytic one Cell or a partial or complete nesting of electrolytic cell, electrolyte container and metal ion generator.

During the passage of a printed circuit board through the electroplating system, the clamps 70 are also metallized in the area of their contacts 82. This layer must be removed before the clips can be used again. This is done in a known manner during the return of the clips to the beginning of the electroplating system. The returning brackets 83 pass through a separate compartment 84 which is connected to the deposition solution in the electrolytic cell 68. For demetallization, the clamps 83 are connected to the positive pole of a rectifier (not shown) via sliding contacts. The negative pole of this rectifier is connected to a cathode plate 85. During the electrolytic demetallization process, copper deposits on the insulating layers of the clamps 83 lose electrical contact with the power supply before they are completely dissolved. Therefore, annoying copper deposits remain in these areas. According to the invention, the parameters for demetallization current and time are therefore set such that, for example, only 70% of the demetallization section is required to remove the metal layer. In the remaining section, Fe ³⁺ ions are generated by the electrolysis current on the metallic and contacted parts of the clamps. These are located exactly where there may still be contactless copper deposits. You dissolve this copper without external current. This does not result in a noticeable increase in Fe (III) ions in the electrolytic cell, because only very small currents and areas are involved in comparison to the metallization of the material to be treated.

To maintain a functional metal separation the copper content in the deposition solution must be determined in certain Limits are kept. This assumes that the consumption rate and the rate of copper ion tracking. The absorbency can be used to check the copper content the separation solution at a wavelength of about 700 nm can be measured. Even the use of an ion sensitive Electrode has proven itself. The measured variable obtained serves as the actual value of a controller, the manipulated variable for maintenance the copper ion concentration in the respective described embodiments of the invention are used becomes.

For analytical tracking of the concentrations of the compounds a potential measurement can be carried out on the redox system will. For this purpose, a measuring cell is used which consists of a platinum electrode and a reference electrode is. By appropriate calibration of the measured potential position with the concentration ratio of the oxidizing and the reduced connections of the redox system for a given Total concentration of the compounds can be the respective Concentration ratio can be determined. The measuring electrodes can be used in the anode and cathode compartments as well as in the pipes the arrangement can be installed.

To control the anode processes, such as the oxidation the redox system required for copper production and a possible anodic decomposition of the additive compounds can be provided a further measuring device in which the Anode potential measured against a reference electrode becomes. For this purpose, the anode is connected to a potential measuring device connected to the corresponding reference electrode.

The continuous or discontinuous metrological Determination of further galvanotechnical parameters is advisable such as determining the content of additive compounds using cyclic voltammetry. So can Temporary postponements after longer breaks Concentrations occur. Knowing the current sizes can be used to incorrectly dose the supplement Avoid chemicals.

The following examples serve to further explain the Invention:

example 1

In an arrangement according to FIG. 2 and using the measures according to the invention (large specific surface area of the copper parts in the metal ion generator, high flow velocity in the entire arrangement, guiding the flow so that the oxidizing compounds of the redox system formed on the anode by oxidation do not adhere to the A copper bath with the following composition was used: 80 g / liter Copper sulfate (C _u SO ₄ · 5 H ₂ O) 180 g / liter Sulfuric acid conc. 10 g / liter Iron as iron (II) sulfate (FeSO ₄ · 7 H ₂ O) 0.08 g / liter Sodium chloride with the following gloss agents: 1.5 g / liter Polypropylene glycol 0.006 g / liter 3-mercaptopropan-l-sulfonic acid, sodium salt 0.001 g / liter N-acetylthiourea

A current yield of 84% was determined. The consumption was determined over 100 Ah / liter to: Polypropylene glycol 3-mercaptopropan-1-sulfonic acid, 3.3 g / kAh Sodium salt 0.3 g / kAh N-acetylthiourea 0.04 g / kAh

The elongation at break of the deposited layers was on End of trial 17%.

Example 2

The experiment in Example 1 was repeated in the arrangement shown in FIG. 3, the deposition solution being passed serially through the cathode and anode compartments. A current efficiency of 92% was achieved. The consumption, again averaged over 100 Ah / liter, was: Polypropylene glycol 2.0 g / kAh 3-mercaptopropan-1-sulfonic acid, sodium salt 0.2 g / kAh N-acetylthiourea 0.02 g / kAh

The elongation at break improved to 20%. In this attempt the coated printed circuit boards survived a double Soldering shock test (10 seconds at 288 ° C soldering temperature) without cracks in the area of the drill holes. The deposition was evenly shiny.

Example 3

In a horizontal system according to FIG. 4, printed circuit boards were copper-plated in a deposition solution of the following composition: 80 g / liter Copper sulfate (C _u SO ₄ · 5 H ₂ O) 200 g / liter Sulfuric acid conc. 8 g / liter Iron as iron (III) sulfate (Fe ₂ (SO _{4) 3} · 9 H ₂ O) 0.06 g / liter Sodium chloride

As brighteners 1.0 g / liter Polyethylene glycol 0.01 g / liter 3- (benzothiazolyl-2-thio) propyl sulfonic acid, sodium salt 0.05 g / liter Acetamide admitted. At an electrolyte temperature of 34 ° C., shiny metal layers were obtained on a scratched copper laminate at a current density of 6 A / dm ² . The PCB metallized in this way passed a five-time solder shock test (10 seconds at 288 ° C soldering temperature). The current yield was 91%. There were no problems with the management (replenishment of the used additives) of the separation solution.

Example 4 (comparative example )

The one described in Example 1 was carried out in an electrolysis cell Experiment carried out. The measures according to the invention were not set, especially not the invention Inflow to the cathodes and anodes.

At a temperature of the plating solution of 30 ° C resulted in a scraped copper laminate surface at a current density of 4 A / dm ² shiny metal layers. The cathodic current yield was only 68%. The consumption of the additive compounds averaged over 100 Ah / liter without dragging the deposition solution by lifting the material to be treated from the bath tank: Polypropylene glycol
3-mercaptopropan-1-sulfonic acid, 5 g / kAh Sodium salt 1.6 g / kAh N-acetylthiourea 0.2 g / kAh

The elongation at break of the deposited layers was on Only 14% end of the trial.

Example 5 (comparative example )

According to Example 1, copper layers were on printed circuit boards deposited after having been on for a long period of time copper had been deposited from the solution on a substrate (2000 Ah / liter).

The circuit boards passed a two-time solder shock test (10 seconds at 288 ° C soldering temperature) no longer without cracks. Uneven copper layers were also obtained. In Examples 1 to 3 could do with good copper layers until very good fracture elongation is deposited. Also the cathodic current efficiency and the consumption of additive compounds, that of the separation solution for controlling the physical-mechanical Layer properties were added, were satisfactory. The appearance of the copper layers was flawless and passed the application tests was standing.

After prolonged loading of the separation solution at Electrolytic deposition of copper, however, were not get flawless results more.

Claims (16)

1. Method for the electrolytic deposition of uniformly thick metal layers of specific physical-mechanical properties, more especially copper layers, having a high electrolytic efficiency, from a deposition solution, containing ions of the deposited metal, compounds of an electrochemically reversible redox system and additive compounds for controlling the physical-mechanical properties of the metal layers, wherein the following are used:

   cathodes;

   insoluble, dimensionally stable anodes;

   a metal ion generator, by means of which the metal ions are formed by dissolving appropriate metal parts whilst the deposition solution, formed by anodic oxidation and containing oxidising compounds of the redox system, are conducted through said generator;

   means, whereby the concentration of the oxidising compounds in the immediate vicinity of the cathode is minimised, preferably to a value below substantially 0.015 mol/litre; and

   means, which bridge a short spacing, for transferring the deposition solution, which flows against the anodes, to the metal ion generator.
2. Method according to claim 1, characterised in that the concentration of the compounds of the redox system is kept slightly below a value which is required to maintain the metal ion concentration.
3. Method according to one of the preceding claims, characterised in that the surface of the metal parts is selected to be so large that the concentration of the oxidising compounds is reduced to a value of substantially zero as they are conducted through the metal ion generator.
4. Method according to one of the preceding claims, characterised in that the deposition solution flows against the anodes at a high velocity of flow and from there is transferred at a high velocity to the metal ion generator.
5. Method according to one of the preceding claims, characterised in that at least a second oxidising compound, preferably oxygen, is additionally introduced to the metal ion generator.
6. Method according to one of the preceding claims, characterised in that a portion of the solution situated in the cathode chamber is transferred directly to the metal ion generator without flowing against the anodes.
7. Method according to one of the preceding claims, characterised in that the deposition solution, conducted through the metal ion generator, flows directly against the cathode and subsequently against the anodes as a result of a deflection of the direction of flow.
8. Apparatus for the electrolytic deposition of uniformly thick metal layers of specific physical-mechanical properties, more especially copper layers, having a high electrolytic efficiency, from a deposition solution which is in contact with cathodes (6, 24, 69) and insoluble, preferably perforated, dimensionally stable anodes (5, 23, 74), comprising

   an electrolyte chamber (I) disposed between the cathodes and anodes;

   devices for causing the deposition solution to flow against the cathodes and anodes;

   a metal ion generator (2, 21, 44, 66);

   a first means for transferring the deposition solution, which flows against the anodes, to the metal ion generator;

   this means bridging a small spatial distance between the anodes and the metal ion generator;

   a second means for transferring the deposition solution, emerging from the metal ion generator, to the electrolyte chamber; and

   additional means, whereby the concentration of oxidising compounds, contained in the deposition solution, is minimised in the immediate vicinity of the cathode.
9. Apparatus according to claim 8, characterised in that means (31, 62, 76) are provided, whereby the deposition solution, situated in the vicinity of the anodes, is evacuated at high velocity or removed via outlets (4, 61, 77) and transferred to the metal ion generator (2, 21, 44, 66).
10. Apparatus according to one of claims 8 or 9, characterised in that the electrolyte chamber (1) is divided into a plurality of compartments by ion-permeable dividing walls (17, 38, 80).
11. Apparatus according to one of claims 8 to 10, characterised in that outlets (18, 75) are provided, whereby the deposition solution, situated in the vicinity of the cathodes, is removed from the electrolyte chamber (I) and transferred to the metal ion generator (2, 21, 44, 66).
12. Apparatus according to one of claims 8 to 11, characterised in that a tubular device, fillable from above, is provided as the metal ion generator (2, 21, 44, 66), said tubular device being provided, in the lower region, with a base (48) and with at least one connection pipe (49) with lateral apertures (50) for the induction of the deposition solution and, in the upper region, with an overflow (54, 78) extending into an electrolyte container (45, 67).
13. Apparatus according to one of claims 8 to 12, characterised by inclined, preferably perforated plates (55) in the interior of the metal ion generator (2, 21, 44, 66).
14. Apparatus according to one of claims 8 to 13, characterised by means for the injection of air (56) disposed in the lower region of the metal ion generator (2, 21, 44, 66).
15. Apparatus according to one of claims 8 to 14, characterised by means (26, 70, 82) for the horizontal picking-up, electrical contacting and displacing of the cathodes in the horizontal direction.
16. Method according to one of claims 1 to 7 for metallising printed circuit boards.

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