WO1998040538A2

WO1998040538A2 - Method for electrolytic deposition of a smooth surface metal on a substrate using graphite dispersion

Info

Publication number: WO1998040538A2
Application number: PCT/DE1998/000667
Authority: WO
Inventors: Jürgen Otto BESENHARD; Heinrich Meyer; Hanna Samy; Christoph Hagg
Original assignee: Besenhard Juergen Otto; Heinrich Meyer; Hanna Samy; Christoph Hagg
Priority date: 1997-03-13
Filing date: 1998-03-02
Publication date: 1998-09-17
Also published as: WO1998040538A3

Abstract

It is difficult to obtain regular metallization during metallization of the total surface of electrically non-conductive substrates covered by a carbon coating. The problem thus arising is that during electrolysis the metal coating can only be developed slowly on the surface of the substrate starting from the electrical contact surfaces. The problem is solved by a method according to which the substrate is initially covered with an electrically conductive base coating and then brought into contact with a dispersion containing graphite particles, surface-active materials used to disperse said particles and a liquid dispersing agent, whereby a fast metallizing graphite layer is formed on the substrate with the graphite dispersion during treatment lasting 30 seconds or less. A metal coating is electrolytically deposited on the graphite layer after said treatment.

Description

Method for electrolytically depositing a metal layer with a smooth surface on a substrate using a graphite dispersion

Description:

The invention relates to a method for the electrolytic deposition of a metal layer with a smooth surface on a substrate.

The metallization of electrically non-conductive or poorly conductive substrates presents difficulties in many cases. In particular, large non-conductive or poorly conductive surfaces cannot be metallized well or only with insufficient quality.

Thin conductive starting layers as the basis for the electrolytic deposition on non-conductive substrates have found widespread technical applications, particularly in the manufacture of printed circuit boards in which the perforated walls have to be metallized to connect several conductors, and in the application of decorative or functional galvanic metal layers over the entire surface on non-conductors, like

Plastic parts.

For example, processes have long been known in which a thin metal layer, for example made of copper or nickel, is first electrolessly deposited in order to produce an electrolytically metallizable surface by adding a reducing agent to the metallizing solution and metal being deposited on suitably catalyzed surfaces with the aid of this reducing agent. This procedure is for a number of years ^¬ the tenth for the metallization of the hole walls of circuit boards and used for decora- tive metallization of plastic components. For example, also for the production of lead-coated plastic grids for lead-acid batteries, in which these are used as electrodes, driving applied (DE-A 39 1 6 71 3), since the electrolytic metal separating fertilizer did not proceed sufficiently quickly according to other pretreatment methods.

However, the use of electroless metallization baths has several disadvantages: Among other things, it is very difficult to monitor these baths, to achieve a uniform quality of the deposited metal layers and to dispose of the large quantities of waste chemicals that arise.

Therefore, processes have been developed that enable direct electrolytic metallization of non-conductive substrates without electroless metallization. For example, intrinsically conductive polymers such as polypyrrole (DE 38 06 884 CD or polyaniline (EP 0 41 3 109 A2) or electrically conductive layers which contain noble metal sulfide (EP 0 320 601 A2) or semiconducting oxides, such as, for example, were used as the first electrically conductive layers Ti0 _2. _X , Pb0 ₂ and Fe ₃ O ₄ .

Other conductive starting layers, including those for the production of printed circuit boards whose plated-through holes are metallized after drilling, can be produced by immersing the cleaned and conditioned printed circuit boards in carbon black and graphite dispersions.

In particular, graphite was selected very early for the production of such electrically conductive starting layers, for example for the electrolytic metal coating of art objects or ceramic building materials (US-A-1, 037,469, US-A-409,096).

It has been found that starting layers made of graphite can generally be galvanized well. However, with finely structured substrates, extremely fine-grained and therefore very expensive types of graphite be set in order to avoid leveling (leveling) of the substrate surface. For this reason, carbon black is used where possible in finely structured substrates, which is of a much finer quality than ordinary graphite and is therefore also significantly cheaper.

US Pat. No. 3,099,608 also states that graphite can be used for the electrolytic coating of perforated walls in printed circuit boards to form a conductive base. However, the publication also states that the graphite coating in particular would have resulted in nonuniform hole diameters, a non-reproducible graphite coating and a poor quality of the metal layers deposited thereon.

A major advantage of carbon black is that it is much easier to disperse in dispersants than graphite, an advantage which is related, for example, to the small particle size (typically 20 to 100 nm), but also to the surface chemistry of carbon black. The surface oxides, which are abundant on structurally disturbed black carbons, such as carbon black, are responsible for the dispersibility and facilitate the chemical interactions with dispersants

(J.O. Besenhard in: Inorganic Reactions and Methods, Vol. 1 7, ed. J.J. Zuckermann, A.P. Hagen, Verlag Chemie, Weinheim 1 990, pages 259 to 284).

For this purpose, EP 0 200 398 B1 describes a method for electroplating a conductive metal layer on the surface of a non-conductive material, a liquid carbon black dispersion being used to form an electrically conductive carbon black layer on the surfaces, and this is then electrolytically metallized.

Another method for producing an electrically conductive layer is specified in DE 41 41 41 6 A1. There is used to fix the soot particles a suitable combination of a high molecular weight substance in a pretreatment solution and a surfactant for stabilization and a salt for destabilizing the carbon black dispersion is used on the surface of the non-conductive substrate. This process has the advantage over the process specified in EP 0 200 398 B1 that the applied soot layer is no longer removed by subsequent rinsing processes, so that a special drying step after the soot coating can be dispensed with. Although the surface conductivity of the printed circuit boards pretreated according to the method according to DE 41 41 41 6 A1 would be sufficiently high for rapid galvanization, in view of the unfavorable surface morphology of the soot coating during the initial phase of the galvanization, a relatively low current density must be used until the the entire surface of the soot is covered with copper. This is especially true when coating larger, non-conductive surface areas, for example when coating plastic parts for decorative or functional purposes (sanitary fittings, electromagnetically shielded housings for electrical devices).

US Pat. No. 5,389,270 discloses an aqueous graphite dispersion which is also to be used for coating perforated walls in printed circuit boards and the subsequent electrolytic metallization.

With known carbon black and graphite dispersions, however, it is difficult to form carbon coatings with sufficient electrical conductivity in order to be able to metallize large, non-conductive substrate surfaces safely and with a uniform layer thickness. For example, very long coating times have to be accepted or the coating process has to be carried out several times. In addition, no known metallization results with satisfactory surface quality are achieved with the known carbon black coatings. With a soot coating, only rough metal layers can be deposited, in particular on rough substrate surfaces. A problem with the electrolytic metallization of large-area non-conductive substrates that are only coated with a thin conductive layer is that at the beginning of the process for forming the metal layer on the thin carbon layer, only relatively small currents can be used, because otherwise the voltage drop in the thin conductive layer creates a very uneven potential distribution over the surface of the substrate. This non-uniform potential distribution means that metal initially deposits only in the vicinity of the contact point and progresses slowly from there to surface areas further away from the contact point until the entire surface is coated with metal. This creates a wedge-shaped thickness profile of the metal layer.

Various measures are available for the formation of uniform metal layers even on large-area substrates: Usually, the problems mentioned are solved either by i) limiting the current densities in the electrolytic metallization or by ii) a correspondingly thicker coating with the conductive carbon around which

Decrease resistance of these starting layers.

However, various disadvantages result from these measures: i) a longer time required for the electrolytic metallization and ii) a possibly undesirable leveling effect, ie a flattening of existing contours of the substrate due to the thick starting layers formed. When thick carbon layers or other conductive layers are formed to produce a sufficiently high electrical conductivity, there are also adhesion problems of the applied carbon and metal films, an increased material consumption and finally also an increased time requirement in the treatment of the substrate with the carbon dispersion and / or the metallization bath. In order to solve the adhesion problem of the graphite layers on the substrate surfaces, it was proposed in EP 0 583 426 B1 to first apply a soot layer and then a graphite layer to the substrate surface. According to the information in the description of this invention, it is also stated that the metallizability of the conductive carbon layer is improved by the additional coating with graphite, since this measure increases the overall electrical conductivity of the layer. Accordingly, it is also proposed that the additional graphite layers be deposited in a layer so thick that the conductivity is generally many times higher than that of the carbon black layer underneath by means of a correspondingly long treatment time with the graphite dispersion (preferably 3 to 5 minutes). This is intended to achieve rapid metallizability of the non-conductive substrates.

Even if a double coating of the non-conductive substrates with carbon black and graphite enables faster metallization of the non-conductive surfaces, it has been found, however, that the inevitably relatively thick carbon layer consisting of carbon black and graphite in turn undesirably causes fine surface contours on the substrate. to be paved. In addition, graphite is relatively expensive

To produce fineness, so that this material is relatively expensive.

The invention is therefore based on the problem that, with the known methods for the direct electrolytic metallization of non-conductive substrates without the use of electroless metallization steps, it is either not possible to metallize even large substrates sufficiently quickly or, with a sufficiently thick conductive starting layer for the subsequent metallization, carbonized surface structures that are present and only a low adhesive strength of the applied layers can be achieved. The problem is solved by the method according to claim 1. Advantageous developments of the invention are specified in the subclaims.

For electrolytic deposition of a metal layer with a smooth surface on an electrically conductive body or one with a conductive one

The following inventive method is carried out as a layer-coated non-conductive body as substrate:

I. contacting the substrate for a treatment time of no more than 30 seconds with a dispersion containing a. Graphite particles, b. surface-active substances for dispersing the particles and c. liquid dispersant, wherein a graphite layer is formed on the substrate surface and

II. Then electrolytic deposition of a metal layer on the graphite layer.

Interestingly, it was found that sufficient metallizability of the substrate can be achieved even if a very thin graphite layer is formed within a very short coating time. The sufficient metallizability can be obtained even if a relatively poorly conductive base layer on a non-conductive body or a relatively poorly conductive body is coated with graphite. Consequently, the electrical conductivity of the graphite layer is not important. For example, the thickness of this graphite layer can generally be far below that of a soot layer, which is required in order to electrolytically deposit a metal layer on a non-conductive body. It is therefore sufficient in the method according to the invention to select a very short treatment time of not more than 30 seconds in order to enable the substrates to be metallized quickly. In most cases, treatment times of 1 5 seconds or less are sufficient, for example show from 2 to 1 0 seconds.

Since the function of the graphite layer is not to increase the electrical conductivity of the starting layer in order to ensure a minimum conductivity of the surface layer, the electrical conductivity of the electrically conductive layer is also irrelevant for the metallizability. Surprisingly, it was found that the function of the graphite layer is to accelerate the rate of propagation of the metal layer deposited on the starting layer by influencing the kinetics of the metal deposition rate.

A scaly or platelet-shaped morphology of the conductive graphite particles is important in order to produce the smoothest possible layer. Consequently, the thickness of the particles should also be small and on average be at least a factor of 5, preferably at least 10, below the diameter of the particles in the surface (thickness / diameter ratio). The average thickness / diameter ratio is understood to mean the number average of the ratio of the thickness of the particles to the diameter of the particles. The quality of the electrolytically deposited metal layers is also significantly increased by the relatively smooth outer layers formed by means of flaky particles compared to the quality that can be achieved on micro-rough substrates. This is due to the fact that a rough or smooth surface morphology of the substrate is at least partially imaged by the deposited metal layers, the memory of the morphology and topography of the substrate being retained even with thicker metal layers. In unfavorable cases, the roughness of the substrate can even be increased by the electrodeposition by the formation of dendrites in particularly exposed areas of the surface (over-leveling).

Even if the starting layer has insufficient electrical conductivity from soot or polypyrrole limits the technically possible maximum metallization speed in a number of cases, so that a sufficiently rapid metallization of even large substrates is only possible if necessary through very thick soot or polypyrrole layers, so even in cases of relatively high electrical conductivity the electrically conductive ones

Starting layers other factors exclusively or at least to a significant extent determining speed or also determining quality.

This becomes particularly clear when relatively thick and thus highly conductive starting layers or even micro-rough substrates that are conductive in volume, such as ceramic sintered bodies made of conductive oxides, such as Ti0 ₂ . _x , are to be electrolytically metallized, since in these cases the conductivity is far above the values required for the electrolytic metallization. In this case, different results with regard to metallizability can be clearly assigned to effects other than electrical conductivity. These effects are due to the improved surface properties of the starting layer, which are caused by the type of graphite particles according to the invention with which the substrate is coated, and the method by which the graphite particles are applied to the non-conductive surfaces.

In particular, the process of the beginning metal deposition is strongly determined by processes such as the formation of metal nuclei and the growth of metal nuclei (see, for example, the textbook Hamann / Vielstich, Elektrochemie II, Taschentext, Verlag Chemie - Physik Verlag, Weinheim, 1 981), the quality of the Substrate plays a crucial role. The main decisive factors are chemical interactions of the substrate with the metal to be electrolytically deposited, which are influenced, for example, by the density and distribution of defects in the starting layers, which facilitate nucleation, or by a suitable surface morphology, by means of which a rapid two-dimensional growth of those already formed Germs can be promoted. The properties of a conductive substrate or an electrically conductive starting layer that are important for the kinetics of electrolytic metal deposition are not necessarily linked to the level of electrical conductivity. Therefore, optimal results for the metallization of non-conductive large-area substrates can generally only be expected if the two most important functions of conductive starting layers for the electrolytic coating of non-conductive substrates are fulfilled at the same time. These properties are, on the one hand, a sufficiently high electrical conductivity of the starting layer and, on the other hand, the property of this layer to allow the highest possible rate of propagation during metallization. The starting layer side facing the metallization bath must in particular have the last-mentioned property. In order to be able to optimize both properties independently of one another, the respective optimal chemical and physical properties of the layers (electrical conductivity or promotion of rapid lateral layer growth) must be assigned to different materials. The technically usable deposition rate is thus optimized by decoupling the required properties by using different ones that are specially adapted to their determination

Materials used for the starting layer.

The concept of decoupling the two aforementioned main functions of the conductive composite starting layer is particularly advantageous if the layer that contributes the greater part of the electrical conductivity is made up of individual conductive particles, since such layers - unlike thin, coherent metal layers - due to their porosity and therefore large inner layers Surface and because of their roughness and numerous grain boundaries characterized to be galvanized interface mostly poor conditions for galvanic metal deposition. This decoupling of the surface properties or the electrical conductivity of the starting layers also enables further optimization, for example with regard to the adhesive strength of the inner contact surface (on the side of the non-conductive substrate) with respect to the substrate or also with regard to the cost of the entire conductive starting layer.

A conductive starting layer according to the invention can, for example, be a composite layer consisting of two or more conductive material layers. According to the invention, the conductive composite starting layers have the

Characteristic that the effect of the component accelerating the kinetics of the galvanic metal deposition on the speed of the spreading of the galvanic deposition is greater than its conductivity contribution.

In one embodiment of the invention, the starting layer consists of an inner layer adjacent to the substrate surface, which is characterized by good electrical conductivity and which is so thick that it has the required conductivity for the subsequent electrolytic metal deposition, and from an electrolyte-side outer layer made of graphite, the The task is to promote the rapid kinetics of the two-dimensional spread of metal deposition. In particular, this outer layer also has a great influence on the quality of the electrodeposited metal layer, since its topography, ductility, crystallinity etc. strongly depend on the type of immediate support, i.e. the graphite layer. Of course, the outer layer is also electrically conductive. However, the thickness of this layer can generally be far below that of the inner layer.

Another variant according to the invention consists in using electrically conductive materials in the volume, for example sintered bodies made of conductive oxides, and coating them with the graphite according to the invention. The surface properties of the conductive materials can be improved by such an outer layer.

The advantages according to the invention with regard to the deposition and spreading speed and in particular also to the quality of the electrolytically deposited metal layers can be achieved with the relatively smooth outer layers which are obtained by coating with flaky conductive graphite particles. Such a coating is achieved by treatment with surfactant-stabilized dispersions of such particles, for example by dipping, spraying or swelling.

Soot particles are preferably used to form the first electrically conductive coating of a non-conductive substrate body. A soot dispersion is used to form the soot layer on the body. For this purpose, an aqueous solution is usually used, which in addition to

Soot particles contain substances to stabilize the dispersion.

In a further preferred process alternative in which carbon black particles are used as the first electrically conductive coating, the process according to the invention further comprises a pretreatment step in which the substrate to be coated is initially coated with a solution of high molecular weight, preferably noticeably water-soluble, and for adsorption on the substrate and as a coagulation trigger suitable substances is treated in order to subsequently coagulate the soot particles on the substrate coated with the coagulation triggers (substrate-induced coagulation). In order to also effectively initiate substrate-induced coagulation, the carbon black dispersion also contains, in addition to the liquid dispersant, a surface-active substance for dispersing the particles and electrolytes as salts which destabilize the dispersion. As a result, the non-conductive surfaces can be electrolytically metallized without the soot layer having to be dried beforehand, since the soot layer is treated by treatment steps carried out after the application of this layer, for example wise rinsing in water is not rinsed off again. In addition, a very firmly adhering and defined soot layer is formed on the substrate surface, since the soot particles are bound to the surface by a high negative enthalpy of adsorption. This applies in an alternative method in which the graphite coating is also based on the principle of substrate-induced coagulation, also in the treatment with the graphite dispersion.

A large number of polymers have proven to be suitable as preferred high-molecular, noticeably water-soluble substances for the pretreatment of the substrates. Good results have been obtained with gelatin, as well as with polyacrylates, which may contain ammonium groups. Water-soluble peptides such as albumins can also be used. In addition, polyelectrolytes can also be used, for example copolymers of acrylamide or methacrylamide with salts or quaternization products of aminoacrylates or other polyelectrolytes which contain simple or substituted ammonium groups. Numerous compounds of this type are commercially available as flocculants. Uncharged polymers, such as polyvinylpyrrolidones, polyvinyl alcohols, polyethylene glycols and their ethers, epichlorohydrin-imidazole adducts, polyvinylimidazoles, polysaccharides and

Sugar polymers are used as well as anionically charged high-molecular substances, such as polycarboxylic acids, for example polyvinyl phosphoric acids.

The type of surfactant stabilizers used to disperse the soot and graphite particles is essential for the functioning of the substrate-induced ones

Coagulation is not critical. Almost all known types of surface-active stabilizers can be used. It is essential that the amount of this agent is so small that spontaneous coagulation on the substrate surface can take place, and is so high that sufficient dispersion stabilization against spontaneous coagulation in the

Volume does not take place. The carbon black and optionally also the graphite dispersion also contains an electrolyte for destabilizing the dispersion. There are also no special restrictions with regard to the type of this substance. Good results have been obtained with sodium acetate, potassium chloride and ammonium nitrate. Customary solvents, preferably water, can be used as the liquid dispersant.

The aforementioned procedure of substrate-induced coagulation makes it possible to carry out the soot coating without subsequent drying of the coated substrate and the electrolytic metallization after a rinsing step immediately after the graphite coating without drying the body coated with graphite. Without this treatment, the soot or graphite layer formed would have to be compressed by drying. Otherwise, the layer would be washed off again with a further wet chemical treatment.

Preferably, the graphite layer optimized for promoting the rate of propagation of the metal layer can be extremely thin, even if the additional electrical conductivity inevitably associated with the additional graphite coating is low compared to the conductivity of the soot layer underneath. This means not only the obvious advantage of saving material, but also the advantage of saving time during the coating process. This applies in particular to coating processes in which the achievable layer thickness depends on the contact time in the coating medium, for example in processes which are based on the adsorption of particles dispersed in the coating medium on a substrate. A short treatment time is advantageous, for example, in the treatment of printed circuit boards that are processed in a horizontal treatment system, since the shortest possible treatment time is desired in order to achieve a high throughput of printed circuit boards per unit of time. This should be well under a minute in the range.

In this preferred variant of the method according to the invention, only a very thin graphite layer formed by an extremely short contact time of the substrate with the graphite dispersion. In order to be able to achieve the advantages according to the invention, it is already sufficient, for example, to bring the substrate into contact with the graphite dispersion during the very short period of 1 to 30 seconds, preferably 2 to 15 seconds.

Even a 5 to 8 second treatment of the substrate with the graphite dispersion leads to very rapid two-dimensional front growth in the metal deposition, so that large-area non-conductive substrates can be electrolytically metallized very quickly. Even with a treatment time of 1 second, one will still be around that

Factor 2 reduced time for the complete coppering of non-conductive surfaces compared to the known methods. Accordingly, the invention is based in particular on the finding that rapid lateral metal growth can be achieved with the graphite particles according to the invention without a corresponding increase in the electrical conductivity of the layer being necessary.

The short treatment times in a graphite dispersion also make it possible to dispense with thorough fixing of the conductive base layer, for example by means of an annealing process. Especially at

Using the substrate-induced coagulation, a very short coating time with graphite can be selected, since a dense graphite coating forms very quickly even if the pretreatment required for the substrate-induced coagulation is carried out with a coagulation trigger only before the soot coating, since the graphite particles adhere particularly firmly to the substrate.

Although the layer optimized for the speed of spreading of the electrodeposition will generally be on the outside, the sequence of the first electrically conductive layer and the graphite particle layer does not necessarily have to be adhered to, as described above. The reverse order also leads to the goal if the electrolyte outer layer is porous to allow electrolyte access to the underlying inner layer. With this inverse constellation, too, the advantage of the faster spreading of the electrolytically deposited metal layer, for example by infiltration of the porous outer layer, can be considerable.

A special case of the inverse constellation in the composite starting layer is when, by means of an outer layer made of a material which is not itself characterized by a favorable influence on the rate of expansion of the metal deposition, an increase even on an inner layer made of graphite particles the spreading or Deposition speed is caused on the composite starting layer thus formed. This effect occurs, for example, when the speed of the electrolytic metal deposition is nevertheless increased because of the finely divided soot on an inner layer made of flaky graphite through an outer layer made of soot, ie a material on which metal layers spread relatively slowly during electrolytic deposition fills and bridges the gaps between the graphite scales.

The possibility of the inverse sequence of the two functional layers naturally offers further optimization possibilities, for example with regard to the adhesive strength of the conductive starting layer on the substrate surface.

The inverse sequence of the two functional layers, i.e. a thin graphite layer applied on the substrate side, which is supplemented by an outside thick soot layer, leads to a considerable acceleration of the technically usable electroplating speed compared to the pure soot layer (or also compared to the pure graphite layer).

The influence of the quality of the outer layers of flaky conductive graphite particles on the quality of electrolytically deposited metal layer can be demonstrated by profilometric measurements using the force microscopy method. For this purpose, the starting layer according to the invention is deposited on polished glass platelets and scanned using a silicon tip for profile height measurement (see Examples 1 2 and 1 3). The smoother character of the metal layers on a substrate, which was coated with graphite in addition to the carbon black coating, becomes very clear. The smoothing effect of the additional graphite coating is also visually recognizable by the significantly higher gloss.

The particle shape of the graphite particles can be determined by scanning electron microscopy (SEM). Furthermore, the ratio of the thickness to the diameter of the particles can also be determined on sieved graphite particles with almost the same particle diameter by a determination according to the BET method.

In a further embodiment, other materials can also be used to form an electrically conductive strat layer. Coatings made from intrinsically conductive polymers, preferably polypyrrole, polythiophene or polyaniline, are particularly suitable.

With the method according to the invention, both small-area and large-area non-conductive substrates can be metallized without problems. In particular, the method is suitable for the large-area metallization of plastic parts for decorative or functional applications, for example parts for the sanitary area, housings for electronic devices which have to be shielded from electromagnetic radiation, automotive parts and parts for the furniture industry and for coating reflectors for lamps. In addition, the method can also be used for the electrolytic metallization of the perforated walls of printed circuit boards and of semiconducting oxides or other conductive ones

Bodies are used. An interesting application is the metal coating of plastic carriers for electrodes in batteries. To reduce the weight of lead accumulators, plastic grids can be used instead of the known solid lead electrodes for the production of electrodes which are electrolytically coated with lead.

A basic distinction must be made between two different applications for the method according to the invention: i) The large-area electrolytic metal deposition is economical, i.e. with reasonable process speed, only possible with very good conductive substrates. Thick conductive coatings or sufficient conductivity in the volume of the body to be coated are thus required, ii) relatively poorly conductive starting layers are sufficient for the production of plated-through holes in printed circuit boards, since metal is electrolytically deposited only in the immediate vicinity of the contact by the copper cladding.

In particular in the examples of large-area metal deposition on very well-conductive substrates, however, it becomes clear that it is not only the conductivity of the substrates to be metallized that is important. A sufficient propagation speed of the metal can no longer be achieved with exclusively highly conductive starting layers. Rather, the morphological, topographical and chemical properties of the surface to be metallized are decisive for the achievable technically usable metal spreading rate.

In principle, any base materials can be coated as substrates, provided adequate adhesion of the metal film can be achieved by a suitable pretreatment process. For example, plastics, ceramics, semiconducting oxides or other chalcogenides can be coated. In principle, the materials that can be coated by electroplating are suitable as plastics: thermoplastics such as acrylonitrile-butadiene-styrene Copolymer (ABS), polyamide, polycarbonate, polyester, polyethylene, polypropylene, polyethylene terephthalate, polystyrene and mixtures thereof, and also thermosets such as epoxy resins, phenolic resins, polyimide, cyanate esters, polytetrafluoroethylene and other halogenated polyalkenes. In addition, inorganic materials can be coated, for example glass, silicon dioxide, aluminum oxide ceramic, titanium dioxide and indium / tin oxide (ITO).

The substrates are first made wettable with a suitable process for the subsequent chemical treatment agents. For

Plastics are usually used in etching solutions, for example chromic acid, chromosulfuric acid or sulfuric acid or alkaline permanganate solutions. If necessary, the plastic surfaces are additionally treated with a suitable organic swelling agent before the etching treatment, for example an alkylene glycol ether or ether ester or their aqueous solutions. After the etching treatment with solutions containing chromium (VI) or permanganate ions, the substrates are treated with suitable reducing agents, for example hydroxylamine or sulfite solutions, in order to remove residues of the etchant. Between the individual treatment steps, the substrates are rinsed, preferably in water.

The surfaces to be treated are then cleaned and conditioned (treatment with adsorption-promoting agents) in order to achieve a sufficient coating with soot. For this purpose, solutions are suitable which contain, among other things, wetting agents, organic solvents and complexing agents, such as nonionic wetting agents, monoethanolamine, ethylene glycol, cationic polyelectrolytes (in particular for conditioning) and other substances. A solution of nonylphenol polyglycol ether in sulfuric acid solution is preferably used. Then the

Rinsed substrate surfaces. In order to achieve substrate-induced coagulation of soot on the substrate, the substances described above can be used for the conditioning can be used. Gelatin, polyvinyl alcohol, for example Mowiof 8-88 (Hoechst AG, Germany), carboxymethyl cellulose sodium salt, polyacrylic acid amide, sodium alginate and polyvinyl pyrrolidone are particularly suitable. Gelatin with a high gel strength is particularly suitable as a coagulation trigger, for example gelatin type B, which is obtained from bovine rind in a basic process. Very good results were obtained in particular with gelatin type 280 B (high gel strength) (manufacturer: Deutsche Gelatinefabrik Stoess AG, Ebersbach, Germany). The substrates are then rinsed again.

Then soot is applied. Carbon blacks with a particle size of at most 3 μm are preferably used. The carbon black is dispersed in a dispersant, preferably water. The dispersion is stabilized by adding surface-active substances, for example hexadecyltrimethylammonium bromide or C ₈ H ₁₇ OOCCH ₂ CH (S0 ₃ Na) COOC ₈ H ₁₇ . to

Destabilization of the dispersion and support for substrate-induced coagulation of the soot on the substrate surfaces may contain an electrolyte, for example sodium acetate, potassium chloride, calcium chloride or potassium sulfate. In this case, the amount of the stabilizing surfactant is kept very short by that

To favor coagulation of the soot. Further, the dispersion may also contain other conventional additives, such as organic solvents Lö ^¬.

If the method for substrate-induced coagulation is used, rinsing can subsequently be carried out. Otherwise, the soot layer on the substrate surface is dried by exposing the substrate to an elevated temperature, for example 80 ^° C.

Then graphite is applied from a graphite dispersion. No further pretreatment is required for this. In particular, conditioning is no longer carried out. A spontaneous coagulation of the graphite on the substrate surface is achieved without using the principle for substrate-induced coagulation, so that the graphite layer is not washed off even during subsequent rinsing. If the graphite is to be deposited by substrate-induced coagulation, a further treatment step with a suitable polymer can also be carried out immediately before the graphite treatment. For the substrate-induced coagulation of the graphite on the soot layer, however, the conditioning agent coating applied before the soot coating is sufficient, which obviously penetrates through the soot layer.

For the graphite dispersion, graphite with particle sizes, preferably from 0.1 to 1.5 μm and a thickness / diameter ratio of at least 5, preferably at least 10, is used. The graphite is wet milled to form the fine particle size in the presence of surfactants. Nonionic surfactants are preferably used to stabilize the graphite dispersion. The same means can be used as for the carbon black dispersion. In addition to the substrate-induced coagulation, an electrolyte for graphite dispersion, for example sodium acetate, is preferably also added. Furthermore, the dispersion can also contain other customary additives, such as, for example, organic solvents.

After the graphite coating, the substrate can be rinsed, especially if the method of substrate-induced coagulation has been used. The graphite layer can then be solidified by drying.

If circuit boards are coated in the specified manner, the carbon layers must be removed from the copper surfaces by etching. Customary copper etching solutions, for example sulfuric acid solutions of hydrogen peroxide or sodium peroxodisulfate, are used for this purpose. After the formation of the double start layer from soot and graphite, the substrate is directly electrolytically metallized. For example, it can be coated with copper, nickel, gold, palladium, tin, lead, iron, cobalt or their alloys with one another or with other elements such as boron or phosphorus. All standard baths can be used for this.

If an intrinsically conductive polymer layer, for example a polypyrrole layer, is formed as the first conductive starting layer instead of carbon black, the plastic substrate to be coated is preferably first treated with an alkaline permanganate solution, so that a brown stone film is formed on the surface by reaction of the permanganate ions with the organic plastic surface . In acidic solution, this film acts as an oxidizing agent against pyrrole, so that when this film comes into contact with a weakly acidic solution of pyrrole, the polypyrrole layer forms, which has good electrical conductivity and good adhesive strength to the substrate surface. In this reaction, the manganese dioxide is reduced to water-soluble manganese salts and thereby removed from the surface. Phosphoric acid is preferably used as the acid in the pyrrole solution. After coating with polypyrrole, the surface can be treated with a conditioning agent to promote adsorption for the graphite coating.

Other electrically conductive base layers can consist of metal films or semiconducting chalcogenides. Good results with full-surface coating with metal are also achieved with ceramic substrates made from Ti0 ₂ . _x powders are sintered, or with substrates made of titanium metal, onto the conductive oxides made of Ti0 ₂ . _{x are} sintered on.

The substrates can be brought into contact with the treatment solutions in a conventional manner by immersion. In the case of printed circuit boards, they are in this case placed vertically in the treatment containers. sunk. Another possibility is to spray or wash the substrates with the treatment solutions. In this case, printed circuit boards in particular can be passed through treatment systems suitable for this purpose.

The invention is illustrated in the following examples:

A: Double-sided copper-clad FR4 (flame retardent) laminates were used to coat PCB holes. The circuit boards consisted of epoxy resin reinforced with glass fibers and had a thickness of 1.6 mm. The thickness of the copper cladding was 35 μm. The dimensions of the circuit board samples were 9.5 cm x 7 cm. Each plate had 54 elongated holes with a length of 4 mm and a width of 1 mm and 48 round holes with a diameter of 1 mm.

B: FR4 laminates laminated on one side with copper were used for coating examples on epoxy resin surfaces. The thickness of the copper cladding was 35 μm and that of the laminates was 1.6 mm.

C: Printed circuit boards with etched copper tracks according to FIG. 1 were used to record the two-dimensional propagation speed of the electrochemical metal deposition on carbon coatings. These test plates were made by exposing and etching one-sided copper-clad and photoresist-coated FR4 laminates

(B) received.

The structure of the etched conductor tracks included three different open, non-copper-covered squares with edge lengths of 3.6 and 10 mm (S3, S6 and S10), which were used to assess the electroplating speed. D: Commercial glass slides were used for coating examples on glass surfaces.

E: Polymer network structures (PNS) as carrier materials for electrodes in lead accumulators were made from two melt-spun ones

Polyester components are produced by knitting a mixed thread into an open-mesh textile fabric and then stiffening it with heat setting. Half of the mixed thread (1 050 dtex) consisted of multifilaments of unmodified, high-strength polyethylene terephthalate (PET) and half of multifilaments of low-melting PET modified with 1 2.5% by weight of isophthalic acid. As a result of the heat-setting of the knitted fabric produced therefrom in an infrared heating field, a rigid polymer grid with mesh openings of alternating 3 mm x 1 mm and 1 mm x 1 mm and a grid strand diameter of 0.5 mm was produced by melting the modified polyester yarn component. without melting the high-strength component. Battery electrode carriers with the dimensions 1 5 cm x 1 3 cm were cut out of this PNS material (manufacturer Hoechst Trevira, Bobingen, Germany).

G 1 to G3: PNS grid, as described under E., with an additional polypyrrole coating, which was applied by Milliken Research, Spartanburg, SC, USA after knitting and before heat setting. The three samples were coated to different extents and therefore differ in surface resistance (measured with a square one

Measuring electrode arrangement on the unfixed knitted fabric): 700 ohms (G 1), 200 ohms (G2) and 1 00 ohms (G3). This PNS material was also manufactured by Hoechst Trevira.

F: coated Ebonex ^® (company Atraverda Ltd., Sheffield, UK) titanium mesh (expanded metal; Supplier: Atraverda Ltd.): Coating with Ebonex ^* -Titanoxid was about 1 50 microns thick and had a average roughness of 3 μm.

The coatings were, if not specifically mentioned, carried out in a vertical immersion system with a horizontal movement of goods. (Stroke: 4 cm, frequency 40 min ^"1 )

Example 1 a:

A printed circuit board, as described under A. above, was prepared for copper metallization as follows: The printed circuit board was treated in the order of the following process steps and immersion baths (1 to 15) with the specified immersion times and temperatures (given in brackets).

Process steps:

1 . Cleaner (1 20 sec, 40 to 60 ° C)

2. Rinse with water (30 to 60 sec) 3. Cleaner to remove drilling dust (30 sec, room temperature)

4. Rinse with water (30 to 60 sec)

5. Solution of a coagulation trigger (60 sec, room temperature)

6. Rinse with water (1 20 sec)

7. Treat in a carbon black dispersion (1 20 sec, 25 to 35 ° C) 8. Rinse with water (30 to 60 sec)

9. Treatment in a graphite dispersion (1 5 sec, 25 to 35 ° C)

1 0. Rinse with water (30 to 60 sec)

1 1. Drying with hot air (60 to 90 sec, 65 to 95 ° C)

1 2. Treat in copper cleaning solution (1 5 sec, room temperature) 1 3. Rinse with water (30 to 60 sec)

1 4. Drying with hot air (60 to 90 sec, 65 to 95 ° C)

1 5. Electrolytic metallization Bath 1 was a cleaner consisting of an aqueous solution of a surfactant (5 g of surfactant and 10 g of concentrated sulfuric acid in one liter of distilled water). Nonionic nonylphenol polyglycol ethers (C ₉ H ₁₉ PhO (CH ₂ CH ₂ 0) ₁₅ H), which are available under the trade name Arkopaf from Hoechst AG, were used as surfactants. Arkopaf 1 10, 1 30 and 1 50 were used; Arkopaf 1 50 was preferably used. For cleaning, the circuit board was treated with ultrasound during the cleaning. After cleaning, the circuit board was rinsed with tap water. The cleaner in process step 3 was used to remove drilling dust from the end faces of the holes exposed in the holes

Inner copper layers. The composition of the bath was as follows:

Sodium peroxodisulfate 1 0.0% by weight conc. Sulfuric acid 2.0% by weight copper sulfate 0.5% by weight

Rest of dest. water

Then the circuit board was rinsed with tap water. The aqueous solution of a polyelectrolyte was used as the coagulation trigger. Gelatin type B 280 (manufacturer: Deutsche Gelatine-Fabrik Stoess AG) with a concentration of 0.2% by weight was used as a suitable polyelectrolyte. The gelatin was dissolved in distilled water at 60 ° C and then stored at a temperature between 4 to 7 ° C for about 20 hours. The gelatin solution was then heated to 20 ° C. and the pH was adjusted to 5.1 (approximately isoelectic point).

The circuit board was then rinsed again in tap water. In the subsequent step, insufficient rinsing would have caused the soot dispersion to coagulate due to the gelatin being carried over. Therefore, this flushing had to be carried out very carefully.

To prepare the aqueous soot dispersion, Printex "L6 (manufacturer: Degussa, Germany) used in water. The anionic surfactant Aerosol OT 1 00 (manufacturer: Cytec Industries BV, the Netherlands) served as stabilization, which was first dissolved in water with heating (40 ° C.) and constant stirring. The appropriate amount of carbon black and sodium acetate were then added. The composition of the

Bades was as follows:

Carbon black Printex ^® L6 1.00% by weight

Aerosol OT 100 surfactant 0.1 2% by weight sodium acetate 0.33% by weight

Rest of dest. water

The circuit board was then rinsed in tap water. Bath 9 was a commercially available aqueous graphite dispersion (Aquadag "from Acheson Industries Germany, Germany), which was diluted with distilled water in a volume ratio of 1 part dispersion to 9 parts water. According to the manufacturer, the average particle size of the graphite particles was between 0.4 and 0 , 6 μm, 0.04 mol / l of sodium acetate as an electrolyte was added to the diluted graphite dispersion with stirring, and then the solution was treated with ultrasound for 5 minutes.

After the circuit board had been treated in the graphite dispersion, it was rinsed with water (process step 10) and then dried with hot air (process step 11). This step was used to evaporate the water from the circuit boards and to increase the adhesion between the carbon particles and the circuit board.

The Scheretch "M etching solution (manufacturer: Atotech Deutschland GmbH, Germany) was used to remove the carbon particles from the copper lamination of the printed circuit boards in process step 1 2. Chen on the borehole walls not affected.

The circuit board was then rinsed again and then dried in process step 14.

Finally, the coated circuit board was electrolytically metallized in an acid copper bath. The bath temperature was 25 ° C and the current density 3 A / dm ² , based on the total surface of the plate. After a coating time of 90 seconds, the drill holes were completely copper-plated, ie the carbon layer was completely covered with copper. The

The composition of the copper bath was as follows:

Cupracid copper bath concentrate *) 250 ml / 1

H ₂ S0 ₄ , formerly pure 1 20 ml / 1 NaCI, formerly pure 40 mg / 1

Basic level Cupracid "BL-CT *) 1 5 ml / 1

Cupracid ^® * 3 ml / 1 gloss additive

Manufacturer: Atotech Deutschland GmbH

Example 1 b:

Example 1a was repeated. However, the samples were dried between steps 8 and 9 (rinsing with water and graphite coating) with hot air (duration 60 seconds). Finally, the coated circuit board was electroplated in an acid copper bath. The bath temperature was 25 ° C and the current density 3 A / dm ² , based on the total surface of the plate. After 75 seconds of metallization, the drill holes were completely copper-plated.

Example 1 c: Example 1a was repeated. However, instead of step 8 (rinsing), the circuit board was dried with hot air for 60 seconds.

Finally, the coated circuit board was electroplated in an acid copper bath. The bath temperature was 25 ° C and the current density 3 A / dm ² , based on the total area of the plate. After 60 seconds the drill holes were completely copper-coated, ie the carbon layer was completely covered with copper.

Example 2 (comparison):

Example 1a was repeated. However, the process was carried out without steps 9 to 11 (graphite coating, rinsing, drying) and the printed circuit board (type A) was prepared for copper metallization (two minutes of treatment time in the carbon black dispersion). The coated circuit board was then galvanically metallized in a copper bath. Only after four minutes (by a factor of 2.7 longer than the copper plating in Example 1 a) were the drill holes completely copper plated.

Example 3 (comparison):

Example 2 was repeated. However, process steps 5 to 8 were repeated (double soot coating with one minute each treatment time). Subsequently and without graphite coating, the coated circuit board was electrolytically metallized in a copper bath. In this case, the boreholes were completely copper-plated after 3 minutes, resulting in a reduction in the electroplating time of only 25% compared to the electroplating time of 4 minutes in Example 2. It follows that less the significant increase in conductivity leads to the increase in the electroplating rate than the surface change due to the graphite coating as in FIG Example 1 (two minutes electroplating time until fully covered).

Example 4:

Six epoxy resin printed circuit boards, as described under B., were treated according to the procedure given above (Example 1 a) up to step 6. The plates (B1 to B6) were then coated twice in the carbon black dispersion for one minute each (steps 7 to 8). The circuit boards (B2, B3, B4, B5 and B6) were then coated with graphite for 1 sec, 5 sec, 1 5 sec, 30 sec and 60 sec (step 9; see Table 1), then rinsed for 60 sec ( Step 1 0) and then dried (Step 1 1). The results are shown in Table 1 and Figure 2.

The circuit boards were then rinsed for 30 seconds and dried for 24 hours. The conductivity of the coated printed circuit boards was measured using the Van der Pauw method. The calculation of the electrical conductivity was therefore based on the following formula:

2 1n2

where σ = electrical conductivity, d = thickness of the layer,

R _{pQ RS} = resistance of the layer when the current is _supplied at P / Q and voltage measurement at R / S,

R _{QR SP} = resistance of the layer when the current is supplied at Q / R and voltage measurement at S / P, P, Q, R and S: there are four contact points near the edges of the sample. Example 5:

Six glass slides (type D) were, as described in Example 4, with

Carbon coated (see Table 2) and the electrical conductivities measured. The results are shown in Figure 3.

Examples 4 and 5 make it clear that the additional coating with graphite only makes a small additional contribution to conductivity.

Nevertheless, as Examples 1 and 2 show, treatment with the graphite dispersion for 15 seconds, which only increases the conductivity according to FIG. 2 by about 30%, can bring about a 100% increase in the electroplating rate.

Example 6:

Six test plates as described under C were treated according to the procedure up to step 6. Test plate C1 was coated with carbon black according to steps 7 and 8 for two minutes. The other plates (C2 to C6) were coated with carbon black twice for one minute each (steps 7 and 8 were repeated once, with a one minute immersion time in the carbon black dispersion). The plates C3 to C6 were additionally coated with graphite according to steps 9 to 11 (different immersion times in the graphite dispersion can be seen in table 3). Then they became two

Metallized in a copper bath at a current of 3 A / dm ² for minutes. The results are shown in Table 3 and Figure 4.

The results show very clearly that the speed of propagation of the copper layer improves drastically as a result of the brief aftertreatment with the graphite dispersion, although this aftertreatment has only minor effects on the electrical conductivity (according to FIG. 2 for example only about 27% after 5 seconds of aftertreatment in the graphite dispersion).

The following examples of large-scale metal deposition relate to grids for lead accumulators, which consist of a synthetic fiber (polyester) core, which can be galvanized with copper and / or lead, for example, after being coated with carbon materials.

The electrode carriers were primarily primarily with relatively high viscosity

Carbon pastes coated grids made of polyester fibers were used, which were then treated for a very short time with graphite dispersions, whereby the technically usable metal deposition rate could be doubled in many cases. The carbon pastes contained carbon black, graphite or graphitized carbon black. Similar drastic improvements have also been achieved with polyester grids coated with a thick layer of highly conductive polypyrrole particles.

Example 7:

A plastic grid in the form of a battery electrode for lead accumulators (PNS electrode), as described above under E., was treated as follows to prepare for copper metallization: The electrode was discontinuously coated with the conductive starting layer made of carbon by immersing the electrode in the corresponding baths. The electrode was coated with the specified immersion times in the order of the following baths (I. to III.):

I. cleaner (1 min) II. Rinsing with water (20 sec)

III. Conductive carbon black paste (60 sec), then dry with compressed air and warm air flow (30 sec) to remove the excess soot paste from the mesh and to dry the layer formed.

For cleaning, the plastic grid in step I (as step 1 above in

Example 1) treated for one minute in a 50 ° C solution of Arkopaf in an ultrasonic bath. After cleaning, the plastic grid was washed with distilled water (step II).

In step III, a paste made of conductivity carbon black Printex ⁸ L6 (10% by weight

Soot; Manufacturer Degussa), an organic water-soluble binder based on polyacrylate (7.5% by weight Basoplast "400 DS: anionic styrene-acrylate dispersion; manufacturer: BASF, Germany), an anionic surfactant (2% by weight aerosol OT100) and distilled water (80.5% by weight) was used to prepare the paste, the surfactant was dissolved in the appropriate amount of water with gentle heating (40 ° C.) with constant stirring, after which the carbon black was added in portions and for about 15 minutes The preparation was treated in an ultrasound bath for a further 10 minutes to deagglomerate and disperse the soot particles, and finally the proportionate amount of binder was added with stirring, and the soot paste was stabilized for a further 10 minutes The plastic grid was immersed in the stirred soot paste for a period of 60 seconds t and then with compressed air and a warm air stream (duration: 30 seconds) freed of excess soot paste in the mesh mesh while drying the soot coating on the mesh strands. The best coating results were obtained at a bath III temperature of 35 to 40 ° C. Example 8:

Coating of plastic grids (type E) with carbon black (treatment time one minute) and graphite (examples 8a to 8d: variation of the immersion times in the graphite dispersion, see table 4). The samples were treated as in Example 7; only after the coating in step III was the electrode 1 immersed in bath 9 (as described above) for 5 sec, 30 sec, 45 sec or 60 sec (examples 8a to 8d).

The plastic grids were then treated with compressed air and in a stream of warm air for 30 seconds in order to remove the excess soot paste from the grid mesh and to dry the coating. A measurement showed no significant increase in the electrical conductivity after a longer coating in bath 9 than 30 seconds (Examples 8b to 8c: approximately the same conductivity, see FIG. 5).

Example 9:

A plastic grid (type E) was coated twice with soot (twice for one minute each). In addition, the grid was held for 1 5 seconds

Graphite coated (according to the procedure according to Example 8a; only the coating in bath III was repeated). An improvement in the conductivity was obtained with double coating with carbon black.

Summary of the results of working examples 7 to 9:

The resistance [kΩ / square] of the coated plastic grids was determined by a two-point measurement on 4 cm x 4 cm pieces of grid which were contacted with conductive silver to avoid contact resistance at two opposite ends. The resistance values are shown in Table 4. The coated plastic electrodes obtained by the processes were metallized with copper by electrolytic deposition of copper using an acidic copper electrolyte bath (bath temperature 25 ° C.) at a current density of 3 A / cm ² .

Bath components content

CuS0 ₄ 5H ₂ 0 80 g / 1 H ₂ S0 ₄ 1 00 ml / 1

NaCI 100 mg / 1

Macuspec 9241 * 2 ml / 1 gloss additive

*) Macuspec 9241 is a product of MacDermid GmbH, Germany

The plastic grid was contacted on one side using conductive silver and dipped vertically into the copper bath with the contact above. The arrangement of the counter electrodes (sacrificial anodes) was parallel to the grid electrode. The criterion for the deposition rate was the

Velocity of propagation of the copper front [cm / min] measured. The results are shown in Table 5.

Examples 10a to 10c:

Plastic grids (PNS electrodes) treated with polypyrrole in the form of battery electrodes for lead accumulators, as described above under G 1 to G3, were immersed in bath 9 in preparation for copper metallization for 30 seconds with constant stirring in order to apply graphite to the grids. The excess graphite dispersion was then removed from the mesh using compressed air and in a hot air stream (treatment time: 30 seconds) and the coating was dried. The preparation and composition of bath 9 is described in Example 1. Results of measurements of the electrical resistance on the treated plastic grids are given in Table 6 and the respective propagation velocities of the copper coating during electrolytic copper plating are given in Table 7.

Examples 10d to 10f (comparison)

As comparative examples to 10a to 10c, the substrates described under G 1 to G3 were tested for their conductivity and their electrochemical deposition behavior without further coating. The results given in Tables 8 and 9 were obtained.

Examples 1 1 a and 1 1 b:

The titanium grids, coated with TiO _{2 ×,} described under F., were immersed in bath 9 for 30 seconds in preparation for copper metallization with constant stirring (Example 1 1 a). The substrate was characterized by a high metallic conductivity (0.3 ohm) with a very rough surface (roughness about 3μm). The coating with a graphite finish had no influence on the conductivity of this substrate.

The coating with graphite made a shiny deposition with copper possible. The comparison with an untreated substrate (Example 1 1 b) showed a deposition rate that was not significantly slower in view of the extremely high conductivity of the substrate, but the metal layer was of a much poorer quality, ie a matt, brownish copper layer compared to a red-gold, shiny one Metal layer (from Example 1 1 a) had. Examples 1 2a and 1 2b:

In order to demonstrate the roughness differences between a sample coated with carbon black and graphite and examined with the aid of force microscopy (AFM), "atomically smooth" graphite substrates (HOPG: Highly

Oriented Pyrolytic Graphite) with the dimensions 1 0 mm x 1 0 mm x 3 mm coated as follows: The coating with carbon black (Example 1 2a; treatment time 2 min) was carried out according to process steps 5 to 8. It was then dried (process step 11). The coating with graphite (example 1 2b; treatment time 1 5 sec) was carried out in accordance with the

Process steps 5, 6 and 9 to 1 1 performed. The samples coated in this way were examined with an AFM device (Nanoscope 3 from Digital Instruments GmbH, Mannheim, Germany) in tapping mode and the roughness profiles (see FIG. 6: carbon black Printex ^™ L6, FIG. 7: graphite Aquadag ") with the aid of the Section Analysis shown

Surfaces were used for silicon tapping mode tips (type TESPW-1).

Examples 1 3a and 1 3b:

To demonstrate the roughness differences of electrolytically deposited copper layers on carbon black (example 1 3a) or on graphite (example 1 3b), HOPG substrates were coated as follows:

The procedure for coating soot was as in Example 1 2a; however, steps 5 to 8 were run through twice (treatment with

Soot each 2 min). The coating with graphite was carried out as in Example 1 3a and the process sequence 9 to 11 was subsequently carried out twice as in Example 1 2b (treatment with graphite for 15 seconds each). The coated HOPG plates were masked on the back and on the side surfaces with paraffin and then with an acidic copper bath

MacDermid (as stated under "Summary of the Results of Examples 7 to 9") each with a current for 20 seconds copper of 1 5 mA. The roughness profiles were determined under the same conditions as specified in Example 12 (FIG. 8: copper deposition on carbon black Printex "L6, FIG. 9: copper deposition on carbon black Printex ^* L6 + graphite Aquadag").

Table 1: Immersion times of Type B PCBs in the carbon black or graphite dispersion

Sample number carbon black dispersion [sec] Graphite dispersion [sec]

B 1 2x60 0 B 2 2x60 1 B 3 2x60 5 B 4 2x60 15 B 5 2x60 30 B 6 2x60 60

Table 2: Immersion times of type D glass slides in the soot or

Graphite dispersion

Sample number carbon black dispersion [sec] Graphite dispersion [sec]

D 1 2x60 0

D 2 2x60 1

D 3 2x60 5

D 4 2x60 15

D 5 2x60 30

D 6 2x60 60 Table 3: The percentage area of the deposited copper in the respective square S3, S6 and S1 0 segment type (see Fig. 1)

Sample number soot disp. Graphite disp. Copper area [%] [sec] [sec] S3 S6 S1 0

C 1 120 0 70.0 50.6 33.0

C 2 2x60 0 81.5 59.5 35.2

C 3 2x60 5 100.0 99.3 78.5

C 4 2x60 15 100.0 98.6 78.2

C 5 2x60 30 100.0 97.7 76.5

C 6 2x60 60 100.0 97.1 74.7

Table 4: Resistance values Examples 7 to 9

Example soot coating graphite resistance

[sec] coating [sec] [kΩ / square]

7 60 - 1, 4

8 a 60 15 D2

8 b 60 30 1, 1 1

8 c 60 45 1, 1

8 8 dd 6 600 6 600 1, 07

9 2x60 15 0.8-0.9 Table 5: Speed of propagation of the copper front during electrolytic copper plating

Example of propagation speed

[cm / min]

7 0.8

8 a 1.5 8 b 1.5

8 c 1.5

8 d 1.6

9 1.7

Table 6: Electrical resistance of a plastic grid covered with a polypyrrole and a graphite layer

Example resistance

[Ω / square]

10 a 345

10 b 127 10 c 62 Table 7: Speed of propagation of the copper layer during electrolytic copper plating on a polypyrene / graphite layer

Example of propagation speed

[cm / min]

13 a 1.3 13 b 1.8 13 c 1.6

Table 8: Electrical resistance of a plastic grid covered with a polypyrrole layer (comparative test)

Example resistance

[Ω / square]

13 d 375

13 e 122

13 f 60

Table 9: Speed of propagation of the copper layer during electrolytic copper plating on a polypyrrole layer (comparative test)

Example of propagation speed

[cm / min]

13 d 0.6 13 e 0.7 13 f 0.6

Claims

Claims:

1 . Process for the electrolytic deposition of a metal layer with a smooth surface on an electrically conductive body or a non-conductive body coated with an electrically conductive coating as a substrate, with the following process steps:

1. contacting the substrate for a treatment time of not more than 30 seconds with a dispersion containing a. Graphite particles, b. surface-active substances for dispersing the particles and c. liquid dispersant, wherein a graphite layer is formed on the substrate surface and

II. Then electrolytic deposition of a metal layer on the graphite layer.

2. The method according to claim 1, characterized in that soot particles are used for the electrically conductive coating of the electrically non-conductive body.

3. The method according to claim 2, characterized in that the body for substrate-induced coagulation of the soot particles first with a solution of high molecular weight, suitable for adsorption on the electrically non-conductive body and as a coagulation trigger and then brought into contact with the soot dispersion, the soot dispersion additionally Contains electrolytes as the dispersion destabilizing salts.

4. The method according to any one of claims 2 and 3, characterized in that the graphite particles are applied to the electrically non-conductive body and the soot layer on the graphite layer.

5. The method according to claim 1, characterized in that intrinsically conductive polymers, preferably polypyrrole, are used as an electrically conductive coating for the electrically non-conductive body.

6. The method according to any one of the preceding claims for electrolytic

Metallization of perforated walls in printed circuit boards.

7. The method according to any one of claims 1 and 2 for the production of electrodes coated with lead for accumulators with a network structure knitted from melt-spun polyester fibers for the electrodes with the following process steps:

a. Cleaning the network structure with an aqueous solution of a wetting agent, b. Coating the cleaned network structure with a carbon-containing paste containing b1. Carbon particles with particle sizes of at most 3 μm, b2. surface-active substances for dispersing the carbon particles, b3. Binder to adjust the viscosity of the paste and b4. a liquid dispersant, c. Coating with the graphite dispersion for a treatment time of no more than 30 seconds, i. Drying the coated network structure, e. Electrolytic metallization of the coated network structure

Copper and then lead.

8. The method according to any one of claims 1, 2 and 5 for the production of electrodes coated with lead for accumulators with a network structure knitted from melt-spun polyester fibers for the electrodes with the following process steps: a. Cleaning the network structure with an aqueous solution of a nonionic wetting agent, b. Forming a layer of polypyrrole on the cleaned network structure, c. Coating the polypyrrole-coated network structure with the graphite dispersion during a treatment time of not more than 30 seconds, i. Drying the grid, e. electrolytic metallization of the coated network structure with copper and then with lead.

9. The method according to any one of the preceding claims, characterized in that the substrate is rinsed after the individual process steps.