TWI764121B - A method for activating a surface of a non-conductive or carbon-fibres containing substrate for metallization - Google Patents

Abstract

The present invention relates to a method for activating a surface of a non-conductive or carbon-fibres containing substrate for metallization, the method comprising the steps (a) providing said substrate, (b) providing an aqueous, palladium-free activation composition comprising (i) a first species of dissolved transition metal ions and additionally metal particles thereof, (ii) one or more than one complexing agent, (iii) permanently or temporarily one or more than one reducing agent, (iv) optionally one or more than one second species of dissolved metal ions being different from the first species, wherein - at least of the first species, the dissolved transition metal ions and the metal particles thereof are present in a reversible equilibrium, with the proviso that - the metal particles are formed from the dissolved transition metal ions through a continuous or semi-continuous reduction through the one or more than one reducing agent, - the dissolved transition metal ions are formed from the metal particles through continuous or semi-continuous oxidation of said particles, and - the dissolved transition metal ions and the metal particles thereof, respectively, are repeatedly involved in said reduction and said oxidation such that no precipitating agglomerates of said metal particles are formed, (c) contacting the substrate with said activation composition such that a transition metal or a transition metal alloy is deposited on the surface of said substrate and an activated surface for metallization is obtained.

Description

Method for activating the surface of a non-conductive or carbon fiber-containing substrate for metallization

The present invention is concerned with activating normally non-conductive or carbon fiber-containing substrate surfaces for subsequent metallization.

In particular, the present invention relates to a method of activating the surface of a non-conductive or carbon fiber-containing substrate for metallization, a method of metallizing the activated surface of a non-conductive or carbon fiber-containing substrate, preparation for activation for metallization A method for activating an aqueous palladium-free activation composition on the surface of a non-conductive or carbon fiber-containing substrate, and an aqueous palladium-free activation composition for activating a non-conductive or carbon fiber-containing substrate surface for metallization.

Often the metallization of such substrates is of high commercial interest. In many aspects of everyday life, such substrates are covered with metallic structures or layers for decorative or functional applications. For example, non-conductive plastic substrates are commonly used to make sanitary articles with glossy chrome layers. In addition, a large number of chrome-coated plastic substrates are used in the automotive industry.

In addition to such decorative items, functional metallization is necessary, for example, in the manufacture of printed circuit boards. In such boards, generally, a non-conductive resin-containing laminate is used as the base material for the circuit, which usually contains copper wires.

Carbon fiber-containing substrates have increasing potential as catalytically active surfaces in, for example, power-to-natural gas, power-to-fuel, and power-to-chemical applications and batteries.

All of these applications require the usual multi-step preparation of non-conductive or carbon fiber-containing substrates to make them acceptable for subsequent metallization.

In the first step, cleaning of the surface of the non-conductive or carbon fiber-containing substrate is usually carried out, eg, to remove grease or impurities.

In the second step, a pretreatment or conditioning of the surface is typically performed to render the surface acceptable for subsequent activation. For example, such pretreatment in some cases includes etching to create pores and enlarge the surface.

In the third step, significant activation is performed. In such activation, typically a very thin seed or activation layer is deposited/anchored on the non-conductive or carbon fiber-containing substrate surface, serving as the starting point for the subsequent first metallization layer. As a result, an activated surface for metallization is obtained. A seed layer or activation layer typically acts as an intermediary between the non-conductive or carbon fiber-containing substrate surface and one or more subsequent metallization layers. Typically, the seed/activation layer is formed by depositing metal nanoparticles on the surface, eg, by a colloidal activation composition.

In a fourth step, the first metallization layer is typically deposited on the seed/activation layer, most typically by electroless plating. In some cases, the electroless plating includes immersion plating, ie, depositing a more noble metal on the seed/activation layer by means of an exchange reaction and in the absence of a reducing agent. In other cases, it includes the deposition of metals or metal alloys by autocatalytic deposition, which means deposition facilitated by means of reducing agents.

In a fifth step, a second metallization layer is deposited on the first metallization layer, usually again by autocatalytic deposition or by electrolytic deposition.

Basically, the skilled person is very familiar with this series of steps. Typically, in common colloidal activation compositions, precious metal nanoparticles, and very often palladium nanoparticles, are used. However, precious metals are generally expensive and wastewater treatment is a high concern in order to recover residual precious metals. Alternatively, cheaper metal ions are also increasingly used in individual activation compositions.

Another common disadvantage is that such activating compositions naturally undergo a form of decay or decomposition. Typically, the nanoparticles coalesce and form insoluble, precipitated agglomerates, rendering the composition largely inoperable. Therefore, it is generally desirable to stabilize the nanoparticles after they have been formed by reduction of the respective metal ions. For this purpose, stabilizer compounds are often used to alter the charge distribution of the particles, limit particle size, and/or prevent particle oxidation. In many cases, polymers and/or antioxidants and/or metal ions (eg, tin ions) are used for these purposes.

For example, CN 107460459 A relates to a simple nano-copper activated liquid using stabilizers and reducing agents to prevent nanoparticle agglomeration and oxidation, respectively.

US 4,278,712 discloses a method for activating weakly reactive colloidal dispersions which can be used to prepare non-conductors prior to electroless plating. The method is based on the controlled oxidation of otherwise weakly reactive colloids by treatment with suitable gases and/or chemical agents, which enables the controlled oxidation. However, at least one colloidal stabilizer must be present. In this way, a reversible equilibrium cannot be maintained.

Such methods as described in the present technology generally suffer from the disadvantage that they are susceptible to coalescence and precipitation sooner or later, mainly because the stabilizer compound does not sufficiently stabilize the particles over time. Therefore, product service life is strongly dependent on production date, delivery time and stable quality.

Furthermore, it appears that such stabilizer compounds often reduce the ability of the nanoparticles to effectively activate the respective surfaces. It appears that the additives on the one hand (at least to a certain extent) avoid agglomeration, but on the other hand prevent such particles from being quickly and strongly adsorbed on the surface. Object of the present invention

It is therefore an object of the present invention to provide a method for activating the surface of a non-conductive or carbon fiber-containing substrate for metallization, and a respective activation composition, which method on the one hand is simple and highly effective, and on the other hand is particularly effective for polymerizing Insensitive to junction and precipitation to ensure long service life. Furthermore, such methods and respective compositions should be inexpensive.

Another object of the present invention is to provide a respective method with a reduced burden on the environment (eg, with less complex wastewater treatment and reduced effective concentrations of chemicals).

Furthermore, the object of the present invention is to provide a respective method of prolonging the service life, especially for the activating composition used.

The above-mentioned objectives are solved by a method of activating the surface of a non-conductive or carbon fiber-containing substrate for metallization, the method comprising the following steps: (a) providing the substrate, (b) providing an aqueous palladium-free activation composition comprising (i) dissolved transition metal ions of the first species and further metal particles thereof, (ii) one or more than one complexing agent, (iii) permanently or temporarily, one or more than one reducing agent, (iv) a dissolved metal ion other than one of the first species or more than one second species, as required, in - At least these first species, the dissolved transition metal ions and their metal particles exist in a reversible equilibrium, with the restriction that - the metal particles are formed from the continuous or semi-continuous reduction of dissolved transition metal ions by one or more than one reducing agent, - the dissolved transition metal ions are formed from metal particles by continuous or semi-continuous oxidation of the particles, and - the dissolved transition metal ions and their metal particles participate repeatedly in the reduction and the oxidation, respectively, so that precipitation agglomerates of the metal particles are not formed, (c) contacting a substrate with the activation composition such that a transition metal or transition metal alloy is deposited on the surface of the substrate and an activated surface for metallization is obtained.

Our experiments have demonstrated that in the present invention, a very simple and effective activation can be achieved even without complex stabilization/antioxidation of the particles formed. In contrast to common activation compositions, stabilization/antioxidation of the particles formed proved to be completely unnecessary. This means that in the present invention the particles are not formed with the goal of maintaining their identity for as long as possible but rather to establish an equilibrium between the dissolved transition metal ions and their respective particles, allowing the particles to be intentional/purposeful Its individual ions are formed again and again by oxidation. Typically, in common activation compositions, oxidation is considered detrimental and is therefore minimized and/or inhibited. In contrast, in the present invention, oxidation is advantageously utilized, is necessary, and is considered to be of great benefit. It turns out that, contrary to common belief, it is not necessary to maintain the particles in the respective activation composition for a long period of time.

This brings many advantages. For example, in a very simple manner, by simply adding the desired reducing agent, the respective activation composition is easily set up/activated where it is needed. This means that the product delivery time is independent of the product/method lifetime.

The present invention relies on the fact that the particles are formed in situ again and again, which makes any stabilizing or stabilizer compounds eliminated. To this end, the dissolved transition metal ions and their metal particles exist in a reversible equilibrium. As a result, very effective and robust activation can be achieved due to the formation of freshly prepared particles with a surrounding shell of stabilizer-free compound having a relatively short lifetime. Subsequently, they are returned to their ionic form by oxidation. After the addition of other reducing agents, fresh granules are formed again (ie in situ).

In the method of the present invention (for activation), a transition metal or transition metal alloy is deposited on the surface of the substrate and an activated surface is obtained for subsequent metallization. This means that the concentration of dissolved metal ions of the first species decreases with time due to deposition. However, replenishment of the first species can be easily achieved by simply adding ions of that species. Therefore, replenishment is extremely easy and simple. Furthermore, this significantly increases the useful life of the respective activation composition and its associated methods.

Furthermore, the respective methods and activation compositions do not necessarily require expensive precious metals but can be performed with low priced transition metals.

In the context of the present invention, "continuously," "continuously," and "continually," respectively, mean the continuous continuation of the respective action while, for example, performing the respective method or aspect of the present invention. without significantly interrupting the action.

In the context of the present invention, "semi-continuously," "semi-continuously," and "semi-continuously," respectively, mean, for example, while carrying out the respective method or aspect of the present invention. One or more than one action of each action even significantly interrupts the progress of the action. In some cases, the interruption time is longer than the time during which the action is being performed. It even only includes temporary and brief actions.

In the context of the present invention, a "species" (eg, a first species or a second species) denotes a chemical element. Thus, "dissolved transition metal ion of the first species" refers to a dissolved metal ion of a transition metal element of Groups 3 to 12 of the periodic table (eg, copper).

In the context of the present invention, "dissolved transition metal ions of the first species and further metal particles thereof" means dissolved metal ions of the first species and further metal particles of the first species, eg in aqueous palladium-free in the activation composition. Substrate:

In step (a) of the method of the present invention (for activation), a non-conductive or carbon fiber-containing substrate and surface are provided. This substrate inherently cannot be successfully metallized and therefore requires activation.

Activation, in the context of the present invention, means modifying the surface of a non-conducting or carbon fiber-containing substrate in such a way that it comprises a transition metal or transition metal alloy after the respective activation step, with sufficient strength for subsequent metallization stickiness. In addition, the deposited transition metals and transition metal alloys, respectively, adhere sufficiently to the surface that subsequent metallization layers (i) can be deposited thereon and (ii) together also adhere sufficiently to the surface of the non-conductive or carbon fiber-containing substrate.

Preferably is a method of the present invention (for activation) wherein the non-conductive substrate comprises (preferably selected from the group consisting of) plastics, resin-containing laminates, glass, ceramics, semiconductors and mixtures thereof.

Preferred plastics include (preferred series) thermoplastics, more preferably (preferred series) polyacrylates, polyamides, polyimides, polyesters, polycarbonates, polyalkylenes, polyphenylenes, polystyrene, polyvinyl or mixtures thereof.

Preferred polyacrylates include poly(methyl methacrylate) (PMMA).

Preferred polyimides include polyetherimides (PEI).

Preferred polyesters include polylactic acid (PLA).

Preferred polycarbonates include polycarbonates (PC) obtained with bisphenol A.

Preferred polyalkylenes include polyethylene (PE), polypropylene (PP), polytetrafluoroethylene (PTFE), polyoxymethylene (POM) or mixtures thereof.

Preferred polyphenylenes include poly(phenylene ether) (PPO), poly(phenylene ether) (PPE) or mixtures thereof.

Preferred polystyrenes include polystyrene (PS), acrylonitrile butadiene styrene (ABS), styrene/butadiene rubber (SBR), styrene-acrylonitrile (SAN).

Preferred polyvinyl groups include polyvinyl chloride (PVC), poly(ethylene-vinyl acetate) (PEVA), polyvinylidene fluoride (PVDF), or mixtures thereof.

Preferred resin-containing laminates include (preferably) fiber-reinforced resin-containing laminates, most preferably glass fiber-reinforced laminates.

Desirably, the resin-containing laminate comprises one or more than one polymer (preferably epoxy resin) resin, imide or mixture thereof) as resin.

An excellent resin-containing laminate comprises (preferably) FR4.

Preferred glasses include (preferably) quartz glass, soda lime glass, float glass, fluoride glass, aluminosilicate glass, phosphate glass, borate glass, borosilicate glass, chalcogenide glass, alumina glass or mixtures thereof.

Preferred ceramics include (preferably) glass ceramics, alumina ceramics, or mixtures thereof.

Preferred semiconductors include (preferably) silicon-based semiconductors, more preferably silicon-based semiconductors including silicon dioxide and/or silicon.

Excellent semiconductor wafers.

Preferably, the method of the present invention (for activation), wherein the carbon fiber-containing substrate comprises (preferably) an arrangement of carbon fiber composites and/or carbon fiber filaments.

Preferred carbon fiber composites comprise (preferably) carbon fiber reinforced polymers and/or carbon fiber-containing fabrics, more preferably carbon fiber reinforced polymers and/or woven carbon fiber-containing fabrics.

Preferred arrangements of carbon fiber filaments include (preferably) fabrics made of carbon fibers, most preferably woven fabrics made of carbon fibers.

A particularly preferred carbon fiber-containing substrate is a carbon fiber-containing felt. Preprocessing:

In some cases, pretreatment of the non-conductive or carbon fiber-containing substrate surface is preferred. Therefore, a method of the present invention (for activation) is preferred, which method comprises, prior to step (c), the step of pre-treating the substrate: (a-1) The substrate is treated with a pretreatment solution containing a nitrogen-containing compound.

Preferably the method of the present invention (for activation), wherein the pretreatment solution has an alkaline pH, preferably in the range of 9.0 to 14.0, more preferably in the range of 10.0 to 13.5, even more preferably in the range of 10.5 to In the range of 13.0, the optimum pH is in the range of 11.0 to 12.5.

Preferably, the method of the present invention (for activation), wherein the nitrogen-containing compound in the pretreatment solution is a polymer, preferably a water-soluble polymer.

Even more preferred is the method of the present invention (for activation) wherein the nitrogen-containing compound in the pretreatment solution is a polymer comprising a pyrrolidine moiety.

Preferably, the polymer is cationic.

Preferably, the nitrogen-containing compound is composed of carbon atoms, nitrogen atoms and hydrogen atoms.

Preferably, the method of the present invention (for activation), wherein the nitrogen-containing compound in the pretreatment solution contains quaternary nitrogen atoms.

Most preferred is the method of the present invention (for activation) wherein the nitrogen-containing compound comprises (preferably) polyquaternary ammonium 6.

Preferably the method of the present invention (for activation), wherein the temperature of the pretreatment solution during step (a-1) is in the range of 20°C to 90°C, preferably in the range of 25°C to 80°C, More preferably in the range of 30°C to 70°C, most preferably in the range of 40°C to 60°C.

It is preferably the method of the present invention (for activation), wherein step (a-1) is performed for 1 minute to 10 minutes, preferably 2 minutes to 8 minutes, more preferably 3 minutes to 6 minutes, and optimally performed for 3.5 minutes. minutes to 5 minutes. Aqueous palladium-free activation composition:

In step (b) of the method of the present invention (for activation), an aqueous palladium-free activation composition is provided.

The aqueous composition used in the method of the present invention (for activation) is an aqueous composition, which means an aqueous main component. Thus, based on the total weight of the aqueous composition, more than 50% by weight of the composition is water, preferably at least 70% by weight, even more preferably at least 90% by weight, and most preferably 95% by weight or more. Only in rare instances, preferably, the composition comprises one or more than one water-miscible solvent (other than water). However, optimal (for ecological reasons) is a method in which water is the only solvent and therefore, optimally, the composition contains substantially no or no organic solvent at all.

In the context of the present invention, the term "substantially free of or not comprising" a subject matter (eg, compound, chemical, material, etc.) independently means that the subject matter is not present at all ("does not contain") or is not present in the present invention It is present ("substantially free") in only minor and non-interfering amounts (ranges) for its intended purpose. For example, such targets may be unintentionally added or utilized, eg, as unavoidable impurities. "Substantially free or free" preferably means 0 (zero) ppm to 5 ppm (based on, for example, the total weight of the activating composition), preferably 0 ppm to 3 ppm, more preferably 0 ppm to 1.5 ppm, Even better is 0 ppm to 1 ppm, best is 0 ppm to 0.5 ppm, even best is 0 ppm to 0.1 ppm. The same principle applies to other targets, eg relative to the total weight of the transition metal or transition metal alloy obtained in step (c) of the method of the invention (for activation).

The activation composition has an acidic pH, a neutral pH or an alkaline pH, preferably an acidic or neutral pH, and most preferably an acidic pH.

Preferably the method of the present invention (for activation), wherein the pH of the activation composition is in the range of ≥ 2.0 to ≤ 13.0, preferably in the range of ≥ 3.0 to ≤ 12.0, more preferably in the range of ≥ 4.0 to ≤ Within the range of 11.0, the best is within the range of ≥4.5 to ≤10.0.

In some cases, the method of the present invention (for activation) is preferred, wherein the pH of the activation composition is in the range of > 3.0 to < 6.5, preferably > 4.0 to < 6.0. Preferably, this applies with the limitation that the one or more than one reducing agent comprises a borohydride.

The pH in the activation composition is generally the result of the presence of (i) to (iv). If pH adjustment is required, this is done by typical methods. Preferred acids are inorganic acids and organic acids. The preferred inorganic acid is sulfuric acid. Preferred organic acids are the acid forms of one or more than one complexing agent. Preferred alkaline compounds are alkaline hydroxides (preferably NaOH), alkaline carbonates (preferably sodium carbonate) and ammonia.

In the context of the present invention, pH is determined at a temperature of 20°C, ie pH as defined refers to 20°C. Therefore, for pH determination purposes only, the temperature of the activation composition was 20°C. This does not mean that the activation composition itself is limited to a specific temperature of 20°C. See below for preferred temperatures for the activation composition.

If the pH is significantly lower than 2 or higher than 13, little sufficient activation is obtained. If the pH is too acidic, the acid-sensitive reducing agent typically decomposes too quickly. Conversely, if the pH is too basic, the alkali-sensitive reducing agent decomposes too quickly.

The aqueous compositions used in the method of the present invention (for activation) are palladium-free. Thus, the activation composition is substantially free or free of palladium ions. This means that neither palladium containing compounds nor palladium atoms/particles or palladium ions are present. Advantageously, the present invention is an excellent alternative to palladium-containing activation methods, with the same or at least nearly the same results in terms of activation.

Preferably, other precious metals or at least expensive/rare metals are also not required in the activation composition. Therefore, preferably the method of the present invention (for activation), wherein the activation composition is substantially free or free of platinum ions, gold ions, silver ions, rhodium ions, ruthenium ions and iridium ions, preferably substantially Contains no or no platinum, gold, silver, rhodium, ruthenium and iridium.

The aqueous composition used in the method of the present invention (for activation) comprises (i) dissolved transition metal ions of the first species and additional metal particles thereof.

Preferred are activation compositions wherein the metal particles are nanoparticles. Preferably, the metal particles comprise one or more than one elemental metal ( ^Me0 ), preferably consist (substantially) of one or more than one elemental metal ( ^Me0 ).

Even better is an activation composition, wherein the particle size of the metal particles of the first species is in the range of 0.1 nm to 500 nm, preferably in the range of 0.5 nm to 200 nm, more preferably in the range of 1.0 nm to 100 nm , preferably in the range of 3 nm to 50 nm, and even optimally in the range of 5 nm to 15 nm.

More preferably is the method of the present invention (for activation) wherein the metal particles of the first species in the activation composition are colloidal metal particles.

Therefore, the method of the present invention (for activation) is preferred, wherein the activation composition is a colloid, preferably a colloidal suspension. However, depending on the coloring effect caused by the dissolved ions of the predominant first species, the activation composition is still a clear but colored solution.

In the activation composition, the dissolved transition metal ions of the first species and the metal particles together form the total amount of metals of the first species. Preferably the method of the present invention (for activation), wherein the metal ions of the first species and their metal particles in the activation composition are formed in the range of 0.05 g/L to 30.0 g/L, preferably 0.07 g /L to 18.0 g/L, more preferably 0.09 g/L to 12.0 g/L, even more preferably 0.11 g/L to 8.0 g/L, most preferably 0.15 g/L Total concentrations in the range of L to 6.0 g/L, even optimally in the range of 0.2 g/L to 3.0 g/L (based on the total volume of the activation composition and based on the ionic, non-particulate form). This means that to determine the total concentration, the transition metal particles of the first species are considered/calculated as dissolved metal ions.

Although the method of the present invention (for activation) can be substantially carried out with relatively high concentrations of the first species, surprisingly, very low concentrations have been shown to be sufficient to obtain very effective and excellent results (see Examples). This is particularly advantageous in terms of wastewater treatment and is therefore cost- and eco-friendly.

Preferably the method of the present invention (for activation) is wherein the first species is copper or cobalt, preferably copper. Copper and cobalt are cost-effective metals compared to commonly used palladium, but achieve sufficient activation on non-conductive or carbon fiber-containing substrate surfaces. The aforementioned concentrations are most suitable for copper and cobalt, and most suitable for copper.

Preferably the method of the present invention (for activation) wherein the source of dissolved copper ions is selected from the group consisting of copper sulfate, copper chloride, copper nitrate, copper fluoroborate, copper acetate, copper citrate, copper phenylsulfonate , copper p-toluenesulfonate and copper alkyl sulfonate group. The preferred copper alkyl sulfonate is copper methanesulfonate. The best copper source is copper sulfate, and the best one is CuSO ₄ * 5 H ₂ O.

Optionally, the aqueous palladium-free activation composition comprises (iv) one or more than one dissolved metal ion of a second species different from the first species. Preferably, the second species is substantially free or free of alkali metals.

Preferably the method of the present invention (for activation) wherein the one or more than one second species is selected from the group consisting of transition metals and magnesium, preferably nickel, cobalt, iron and magnesium, preferably nickel and cobalt, more preferably nickel group. For the dissolved metal ions of the second species, the respective transition alloy is preferably deposited in step (c) of the method of the present invention (for activation).

Preferably the method of the present invention (for activation) is wherein the one or more than one second species is substantially free or free of tin.

In addition to the first species and optionally the second species, the aqueous palladium-free activation composition comprises (ii) one or more than one complexing agent. Preferably, the one or more than one complexing agent is adapted to form a complex with at least the dissolved transition metal ion of the first species.

Preferably the method of the present invention (for activation), wherein the one or more than one complexing agent comprises or is an organic complexing agent, preferably a carboxylic acid and/or its salt, more preferably a di- or tricarboxylic acid and/ Or its salt, even more preferably tricarboxylic acid and/or its salt, most preferably hydroxytricarboxylic acid and/or its salt, even most preferably citric acid, its structural isomer and/or its salt. The preferred structural isomer system is isocitrate and its salts. Optimally, the one or more than one complexing agent as defined above, including preferred variants, is the only complexing agent in the activating composition.

Preferably the method of the present invention (for activation), wherein in the activation composition - based on the total volume of the activation composition and based on the ionic, unspecified form, the metal ions of the first species and their metal particles together constituting the total concentration, and - one or more than one complexing agent in the total concentration It is in the range of 1.0:0.2 to 1.0:100.0, preferably in the range of 1.0:0.5 to 1.0:50.0, more preferably in the range of 1.0:0.85 to 1.0:25.0, even more preferably in the range of 1.0:0.95 to Molar ratios exist in the range of 1.0:15.0, and even better in the range of 1.0:1.0 to 1.0:10.0, most preferably in the range of 1.0:1.1 to 1.0:5.0. This applies particularly well if one or more than one complexing agent comprises tricarboxylic acids and/or salts thereof, more preferably hydroxytricarboxylic acids and/or salts thereof, most preferably citric acid, structural isomers and/or salts thereof .

Preferably the method of the present invention (for activation), wherein the one or more than one complexing agent in the activation composition is in the range of 0.01 mol/L to 0.5 mol/L (based on the total volume of the activation composition) , preferably in the range of 0.015 mol/L to 0.35 mol/L, more preferably in the range of 0.02 mol/L to 0.3 mol/L, and most preferably in the range of 0.023 mol/L to 0.275 mol/L quantity exists.

In addition to the first species, the optional second species, and one or more than one complexing agent, the aqueous palladium-free activation composition permanently or temporarily comprises (iii) one or more than one reducing agent. The one or more reducing agents are necessary for the formation of metal particles from dissolved transition metal ions of at least the first species. To this end, the dissolved transition metal ions are chemically reduced (continuously or semi-continuously) to form the particles. Thus, the particles are formed continuously or semi-continuously, respectively, depending on the presence of one or more than one reducing agent (either permanently or temporarily) in the activating composition. However, when one or more than one reducing agent is present, the particles will generally be formed until the reducing agent is used up or deficient. Preferred are methods of the present invention (for activation) wherein oxidation affects the particles and continuously competes with reduction. Typically, oxidation begins as soon as the one or more reducing agents have been used up, which is expressly desired in the context of the present invention.

If, in the process of the invention (for activation), after one or more than one first step (c), the process is interrupted for a relatively long period of time, the oxidation is additionally highly relevant. To prevent the precipitation of agglomerates during this period of time, the oxidation is carried out in the activation composition until no more particles are present but only dissolved transition metal ions. Preferably, oxidation is promoted by adding an oxidizing agent, more preferably a peroxide, most preferably hydrogen peroxide. After resumption of operation, the particles are formed by continuously or semi-continuously adding one or more than one reducing agent to reformulate the particles. Afterwards, the method of the present invention (for activation) is resumed.

Thus, preferably, the one or more than one reducing agent is suitable for reducing at least the dissolved transition metal ions of the first species.

In some cases, the method of the present invention (for activation) is preferred, wherein the one or more reducing agents comprise one or more than one hydrogen atom such that hydrogen is released immediately upon reduction of the transition metal ion, the transition metal Ions are at least partially adsorbed on the activated surface.

Preferably the method of the present invention (for activation), wherein the one or more than one reducing agent comprises a boron-containing reducing agent, preferably a borohydride. Preferred borohydrides include inorganic borohydrides and/or organic borohydrides. Preferred organoborohydrides include alkylaminoboranes, most preferably dimethylaminoborane. Preferred inorganic borohydrides include basic borohydrides, most preferably sodium borohydride. In the method of the present invention (for activation), the most preferred is an alkaline borohydride, preferably sodium borohydride. This allows the weakly acidic pH and temperature in step (c) of the method of the present invention (for activation) to be within an appropriate range (preferably 15°C to 30°C). These are excellent room temperature conditions. Therefore, no additional and cost-intensive heating is required. In addition, hydrogen is produced.

Preferably, boron-containing reducing agent, preferably borohydride, more preferably basic borohydride and/or alkylaminoborane, preferably sodium borohydride and/or dimethylaminoborane-based activation The only reducing agent in the composition.

As a result of the use of borohydride as one of the one or more than one reducing agents in the activation composition, boric acid and/or its salts are typically formed.

In some cases, preferably the method of the present invention (for activation), wherein the one or more than one reducing agent comprises an aldehyde (preferably formaldehyde), glyoxylic acid, a salt of glyoxylic acid or mixtures thereof, most preferably as the only reducing agent. In this case, the formation of boric acid is avoided.

In some cases, the method of the present invention (for activation) is preferred, wherein the one or more than one reducing agent includes hydrazine, most preferably as the sole reducing agent. Furthermore, in this case, the formation of boric acid is avoided.

Preferably the method of the present invention (for activation), wherein the activation composition comprises a total concentration in the range of 0.2 mmol/L to 500.0 mmol/L (based on the total volume of the activation composition), preferably 0.4 mmol/L L to 350.0 mmol/L, more preferably 0.6 mmol/L to 250.0 mmol/L, even more preferably 0.8 mmol/L to 150.0 mmol/L, most preferably 1.0 mmol/L One or more than one reducing agent in the range to 80.0 mmol/L. The optimal total concentration is in the range of 0.9 mmol/L to 50.0 mmol/L, the best is in the range of 1.0 mmol/L to 30.0 mmol/L, the best is in the range of 1.1 mmol/L to 10.0 mmol/L . Optimally, this applies to the aforementioned preferred, better, etc. reducing agents; optimally applies to borohydrides.

In general, preferred is the method of the present invention (for activation) wherein the activation composition is - based on the total volume of the activation composition and based on the ionic, unspecified form, the metal ions of the first species and their metal particles together constituting the total concentration, and - one or more than one reducing agent (if added semi-continuously, at the time of addition) in the total concentration It exists in a molar ratio of more than 0.5, preferably 1 or more, more preferably 2 or more, even more preferably 3 or more, and most preferably 3.5 or more. Excellent is a molar ratio in the range of 1 to 20. Thus, in the activation composition, the one or more reducing agents are preferably present in some total concentration (permanently or temporarily) such that the dissolved transition metal ions of the first species are not quantitatively reduced to the respective particles. Furthermore, preferred is the method of the present invention (for activation) wherein the activation composition does not primarily exhibit a reducing environment to prevent oxidation of the metal particles. Rather, as already mentioned, oxidation is required and desired. Therefore, the method of the present invention (for activation) is preferred wherein the activation composition is primarily maintained under oxidizing conditions to allow oxidation of the metal particles.

Particularly preferred is the method of the present invention (for activation), wherein in the activation composition - based on the total volume of the activating composition and on the basis of the ionic, non-specific forms of the metal ions of the first species and their metal particles which together constitute the total concentration, and - One or more than one reducing agent in total concentration (if added semi-continuously, at the time of addition) It is in the range of 0.3 to 60.0, preferably in the range of 0.5 to 30.0, more preferably in the range of 1.0 to 20.0, even more preferably in the range of 1.5 to 10.0, most preferably in the range of 1.8 to 3.0 Morbi exists.

In some cases, the method of the present invention (for activation) is preferred, wherein the one or more reducing agents are permanently present in the aqueous palladium-free activation composition. Thus, it is preferred to continuously add one or more than one reducing agent to the activation composition, preferably by permanently flowing the respective liquids comprising the one or more than one reducing agent. In this process, oxidation and reduction occur simultaneously over time during step (c) of the process of the present invention (for activation). As a result, the metal particles are present in a relatively constant concentration.

Alternatively, and preferably, the method of the present invention (for activation), wherein the one or more than one reducing agent is temporarily present in the aqueous palladium-free activation composition. Thus, preferably, the one or more than one reducing agent is added semi-continuously; for example in successive portions, with time interruptions between each portion. This means that fresh granules are formed when one or more than one reducing agent is added. During the interruption, however, it is extremely important that the oxidation produces dissolved transition metal ions. Thus, the metal particles are present in substantially variable concentrations. However, depending on the length of time interruption and ensuring that the interruption is not too long, this method is quite sufficient to successfully activate even the surfaces of multiple non-conductive or carbon fiber-containing substrates. Therefore, this method is particularly preferred.

In either case, however, the method of the present invention (for activation) is preferred wherein the one or more reducing agents are present in such a way that the equilibrium remains reversible. Therefore, reversible equilibrium is not only a side reaction or an undesired side reaction.

After oxidation, due to reversible equilibrium, the total concentration of the dissolved transition metal ions in the activation composition substantially increases, wherein the total amount of metal particles decreases. For better process control, the reversible equilibrium is preferably monitored. Therefore, the method of the present invention (for activation) is preferred, wherein the reversible equilibrium is monitored by UV/VIS inspection. Preferably, the dissolved transition metal ions are in the range of 700 nm to 800 nm, preferably in the range of 710 nm to 780 nm, more preferably in the range of 720 nm to 760 nm, most preferably in the range of 730 nm Monitor at wavelengths in the 750 nm range. Also preferably, the metal particles are monitored at wavelengths in the range of 400 nm to 600 nm, preferably in the range of 450 nm to 550 nm. This allows determining when to add the one or more than one of the reducing agents to form (preferably reformulate) the metal particles to increase their total amount.

Thus, preferably the method of the present invention (for activation) wherein the one or more than one reducing agent is continuously or semi-continuously added to the activation composition such that the dissolved transition metal ions from the first species, respectively, is continuous Or other metal particles are formed semi-continuously, preferably added after performing the one or more than one step (c).

Preferably the method of the present invention (for activation), wherein the metal particles of the first species are continuously or semi-continuously formed in situ by the reduction after and/or during one or more than one step (c) in the activation composition. This is preferably defined as, in the method of the present invention (for activation), step (c) is performed more than once, preferably the method comprising step (c) is performed repeatedly. Preferably, after one, more than one or each step (c) of the method of the invention (for activation), the metal particles are newly formed by this reduction. This is possible because the oxidation is allowed and desired, preferably continuously, but at least semi-continuously, resulting in freshly prepared dissolved transition metal ions ready for re-reduction. This is in contrast to conventional methods, where metal particles are formed (and stabilized) before activation is performed, which is followed by stabilization of the particles for as long as possible until the respective activation composition is unstable and inoperable.

As mentioned throughout, in the context of the present invention it is preferably necessary to add the reducing agent at least semi-continuously. Typically, the reducing agent used for this reduction reacts with the dissolved transition metal ions and produces a reducing agent degradation product, preferably boric acid and/or its salts. Often, such degradation products accumulate in the activation composition, which is not preferred in the context of the present invention. Therefore, the method of the present invention (for activation) is preferred, wherein the method is carried out by bleed and feed. In this method, a volume of the activation composition is removed (eg, by extraction; thereby also removing degradation products) and replaced by a displacement volume in such a way that the necessary components in the activation composition have a sufficiently constant concentration ( For example, by means of supplements). This means that the displacement volume generally contains no boric acid and/or its salts, preferably no reducing agent degradation products. It is also beneficial to stabilize the pH to a substantially constant pH.

Preferably the method of the present invention (for activation), wherein the activation composition comprises a total concentration of 5 g/L or less (based on the total volume of the activation composition), preferably 3 g/L or less, More preferably 2 g/L or less, most preferably 1.2 g/L or less of boric acid and/or its salts. This preferably applies with the following limitations: (1) one or more than one reducing agent includes a borohydride and (2) step (c) is performed more than once.

Preferred is the method of the present invention (for activation) wherein the reversible equilibrium is not largely deviated to the metal particles during most of the time step (c) is carried out.

Preferred is the method of the present invention (for activation) wherein during and/or after step (c) a majority of the metal particles undergo the oxidation. Most preferably represent more than 50% particles.

Preferably, the one or more than one reducing agent is substantially free or free of hypophosphite ions, preferably substantially free or free of phosphorus-containing reducing agents. Our experiments have shown that, in some cases, activation with such reducing agents is too weak or even incomplete.

As already outlined above, the activation composition does not additionally require a stabilizing compound. Therefore, preferably the method of the present invention (for activation) is wherein the activation composition is substantially free or free of compounds that prevent oxidation of metal particles and/or is substantially free or free of compounds that stabilize metal particles stabilizer compound. Preferably, the activation composition is substantially free or free of stabilizer compounds that stabilize the metal particles by preventing agglomeration of the metal particles. In the context of the present invention, the one or more than one reducing agent (temporarily or permanently present in the activation composition) and the compounds involved in oxidation (preferably ambient air and/or oxygen (ie, optimal molecular oxygen) ) are not considered to be such compounds. Rather, one or more than one reducing agent is required in order to form the metal particles, which includes reforming the particles. This means that the activating composition is substantially free or free of stabilizer compounds and/or compounds that prevent oxidation of the metal particles other than the one or more reducing agents and compounds involved in oxidation. Therefore, it is preferred that the method of the present invention (for activation), wherein the one or more than one reducing agent is not present in an amount to prevent oxidation, preferably not to prevent after one or more than one step (c) or The total amount of oxidation is present during the period. As outlined, oxidation, preferably by oxidation of ambient air, is required to reform the dissolved transition metal ions so that precipitation agglomerates of the metal particles are not formed.

Preferably the method of the present invention (for activation) is wherein the activation composition is substantially free or does not contain compounds that fully or partially encapsulate metal particles or that are fully or partially adsorbed to the surface of the particles. It is believed that some stabilizer compounds are based on this function. In the context of the present invention, this is not desired.

In general, preferred are methods of the present invention (for activation) wherein the activation composition is substantially free or free of compounds that prevent reversibility of equilibrium and/or is substantially free or free to complete equilibrium Compounds that deviate towards metal particles. Likewise, the one or more reducing agents are not considered to be such compounds for the reasons outlined above.

Preferably the method of the present invention (for activation) wherein the activation composition is substantially free or free of tin ions, preferably substantially free or free of tin ions, lead ions, germanium ions, gallium ions , antimony ions, bismuth ions and aluminum ions, and more preferably substantially free or free of metal ions of main groups III, IV and V of the periodic table of elements. In the context of the present invention, "metal ions of main group III" do not include the respective boron-containing ions. In particular, tin ions are well known to prevent oxidation of copper particles, such as in copper-tin activation compositions without palladium, respectively, thereby preventing the equilibrium from being reversible. Such tin ions generally form a reducing environment, which is by no means contemplated in the context of the present invention.

Preferably the method of the present invention (for activation), wherein the activation composition is substantially free or free of polyvinylpyrrolidone, preferably substantially free or free of polyvinyl compounds, more preferably Substantially free or free of organic polymers containing vinyl moieties, most preferably substantially free or free of dissolved organic polymers.

Preferably the method of the present invention (for activation) is wherein the activation composition is substantially free or free of proteins, agar, gum Arabic, sugars and polyols.

Preferably the method of the present invention (for activation) is wherein the activation composition is substantially free or free of glycerol.

Preferably the method of the present invention (for activation) is wherein the activation composition is substantially free or free of gelatin.

Preferably the method of the present invention (for activation), wherein the activation composition is substantially free or free of thiourea, preferably substantially free or free of sulfur-containing compounds with divalent sulfur, more preferably A sulfur-containing compound with an oxidation number of +5 or less that is substantially free or free of sulfur.

Preferably, the method of the present invention (for activation), wherein the activation composition is substantially free or free of compounds containing aromatic rings and sulfonic acid groups (including salts thereof), preferably substantially free or Does not contain sulfonic acid or its salts.

Preferably the method of the present invention (for activation) is wherein the activation composition is substantially free or free of a compound known as Orzan-S.

Preferably the method of the present invention (for activation) is wherein the activation composition is substantially free or free of urea.

Preferably the method of the present invention (for activation) is wherein the activation composition is substantially free or free of dispersants.

Preferably the method of the present invention (for activation), wherein the activation composition is substantially free or free of polyethyleneimine, preferably substantially free or free of polyalkyleneimine, most preferably are substantially free or free of organic polymers containing imine moieties.

In particular, polymers as mentioned above are often used as stabilizer compounds to stabilize metal particles. However, in the context of the present invention, polymers are not necessary. Furthermore, it is believed that without such molecules forming a shell around the particles, the metal particles are significantly more effective/active.

Preferably the method of the present invention (for activation) wherein the activation composition is substantially free or free of sodium dodecyl sulfate, preferably substantially free or free of having 8 to 20 carbon atoms The alkyl sulfates are more preferably substantially free or free of alkyl sulfates, and most preferably substantially free or free of surfactants.

Preferably the method of the present invention (for activation) wherein the activation composition is substantially free or free of hydroquinone, pyrogallol and/or resorcinol, preferably substantially free or without hydroxybenzene. In many cases, such hydroxybenzenes are commonly used as antioxidants, preventing the equilibrium from being reversible, which is not desired in an activating composition.

Preferably the method of the present invention (for activation) is wherein the activation composition is substantially free or free of quinones.

Preferably the method of the present invention (for activation) is wherein the activation composition is substantially free or free of fatty alcohols.

Preferably the method of the present invention (for activation) is wherein the activation composition is substantially free or free of alkanediols, preferably substantially free or free of glycols.

Preferably the method of the present invention (for activation) is wherein the activation composition is substantially free or free of manganese ions.

Preferably the method of the present invention (for activation) is wherein the activation composition is substantially free or free of zinc ions.

Thus and in particular, although the activation composition does not include stabilizing compounds and/or compounds that prevent oxidation of the metal particles, preferably the method of the present invention (for activation) is wherein the activation composition is substantially free or free of Precipitated agglomerates comprising these metal particles. This is achieved because the oxidation is not inhibited (ie not avoided), but at least the dissolved transition metal ions of the first species and their metal particles are repeatedly involved in the reduction and the oxidation, respectively.

Preferably the method of the present invention (for activation), wherein "repetitive participation" specifically includes at least more than once, preferably more than two times, even more preferably more than three times, most preferably more than four times, and even optimally the activation of the composition. throughout the service life.

Our experiments have shown, in particular, that it prevents the oxidation of coalescence. The metal particles are oxidized back to their ionic/dissolved form. This means that there is not enough time for the particles to form higher aggregates and even agglomerates. While basically every suitable oxidant is suitable, ambient air has proven to be an excellent choice. It's strong enough and ubiquitous. Preferred is the method of the present invention (for activation) wherein by the oxidation, preferably by oxidation of ambient air and/or oxygen, the formation of precipitation agglomerates of the metal particles is prevented. Preferred is the method of the present invention (for activation) wherein the dissolved transition metal ions are formed from metal particles by oxidation of ambient air and/or oxygen. In both cases, the preferred oxidant is molecular oxygen. Best is the method of the present invention (for activation) wherein most of the dissolved transition metal ions are formed from the oxidation of most metal particles by ambient air and/or oxygen.

In some cases, the method of the present invention (for activation) is preferred, wherein the continuous or semi-continuous oxidation is by an oxidizing agent that is not molecular oxygen, more preferably by peroxide, most preferably hydrogen peroxide, additionally or achieved individually. In particular, in addition to ambient air, this preferably promotes oxidation of the particles if this is desired, eg, if the activating composition must be inactivated and stored for longer periods of time.

To adequately promote oxidation in an activation composition, the method of the present invention (for activation) is preferred, wherein the activation composition is preferably circulated continuously or semi-continuously by shaking, stirring and/or pumping. This preference ensures that the oxidation is evenly distributed throughout the activation composition. In other words, this ensures that the metal particles are in equal contact with the oxidizing agent, which promotes oxidation.

The very best system (for activation) method for metallization of non-conductive or carbon fiber-containing substrate surfaces, the method comprising the following steps (a) providing the substrate, (b) providing an aqueous palladium-free activation composition comprising (i) dissolved transition metal ions of a first species and other colloidal metal particles thereof, wherein the first species is copper, (ii) one or more than one complexing agent comprising hydroxytricarboxylic acids and/or salts thereof, preferably citric acid, structural isomers and/or salts thereof, (iii) permanently or temporarily, one or more than one boron-containing reducing agent, preferably a borohydride, (iv) dissolved metal ions different from one of the first species or more than one second species, preferably nickel, as desired, in - the activating composition is a colloidal suspension, and - At least these first species, the dissolved transition metal ions and their metal particles exist in a reversible equilibrium, with the restriction that - the metal particles are formed from the continuous or semi-continuous reduction of dissolved transition metal ions by one or more than one reducing agent, - these dissolved transition metal ions are formed from the continuous or semi-continuous oxidation of metal particles by oxidation of the surrounding air, - the dissolved transition metal ions and their metal particles participate repeatedly in the reduction and the oxidation, respectively, so that precipitation agglomerates of the metal particles are not formed, and (c) contacting a substrate with the activation composition such that a transition metal or transition metal alloy is deposited on the surface of the substrate and an activated surface for metallization is obtained, wherein the metal particles are subjected to one or more than one The reduction is continuously or semi-continuously formed in situ in the activation composition after and/or during step (c).

The present invention also relates to a preparation of an aqueous palladium-free activation composition for activating the surface of a non-conductive or carbon fiber-containing substrate for metallization (preferably activation as used in the method of the present invention (for activation) composition) method, the method comprises the following steps (1) Provide an aqueous starting solution containing - the dissolved transition metal ion of the first species, - one or more than one complexing agent, and - as required, a dissolved metal ion other than one of the first species or more than one second species, (2) continuously or semi-continuously adding one or more than one reducing agent to the starting solution such that metal particles of dissolved transition metal ions of at least the first species are formed in the solution continuously or semi-continuously, respectively, The limitation is that the metal particles are continuously or semi-continuously oxidized to form dissolved transition metal ions of the first species.

The foregoing about the method of the present invention (for activation) preferably applies equally to the method of the present invention for the preparation of an aqueous palladium-free activation composition, most preferably, as defined above.

The present invention also relates to continuous or semi-continuous reduction of dissolved transition metal ions of the first species in reversible equilibrium combining continuous or semi-continuous oxidation of metal particles of the first species for continuous or semi-continuous oxidation in aqueous palladium-free activation compositions Use for continuous in-situ formation of metal particles.

The foregoing with respect to the method of the present invention (for activation) preferably applies equally to the use of the present invention, most preferably, as defined above.

The present invention also relates to an aqueous palladium-free activation composition for activating the surface of a non-conductive or carbon fiber-containing substrate for metallization, the composition comprising (i) dissolved transition metal ions of the first species and further metal particles thereof, (ii) one or more than one complexing agent, (iii) permanently or temporarily, one or more than one reducing agent, (iv) dissolved metal ions other than one of the first species or more than one second species, as required, in - At least these first species, the dissolved transition metal ions and their metal particles exist in a reversible equilibrium, with the restriction that - the metal particles are formed from the continuous or semi-continuous reduction of dissolved transition metal ions by one or more than one reducing agent, - the formation of the dissolved transition metal ions from the metal particles by continuous or semi-continuous oxidation of the particles, and - The dissolved transition metal ions and their metal particles repeatedly participate in the reduction and the oxidation, respectively, so that precipitation agglomerates of the metal particles are not formed.

The foregoing with regard to the method of the present invention (for activation) preferably applies equally to the aqueous palladium-free activation composition of the present invention, most preferably, as defined above.

Preferably, the activation composition of the present invention is in the range of 10°C to 90°C, preferably in the range of 14°C to 75°C, more preferably in the range of 16°C to 65°C, most preferably in the range of 18°C to 45°C. This temperature can be obtained and/or possessed at a temperature in the range of °C, even optimally in the range of 20°C to 32°C. Specifically, the temperature is preferably in the range of 18°C to 45°C, preferably in the range of 20°C to 32°C, and the limitation is that one or more than one reducing agent is borohydride, preferably sodium borohydride. . In particular, this also preferably applies to the method of the present invention (for preparing the activation composition) and the method of the present invention (for activation).

More preferably, the activation composition of the present invention is not obtained at and/or does not have a temperature above 110°C, preferably above 100°C, more preferably above 95°C. Optimally, the activation compositions of the present invention are not obtained at temperatures above 110°C. The same preferably applies to the method of the present invention (for preparing the activation composition) and the method of the present invention (for activation). activation:

In step (c) of the method of the present invention (for activation), the substrate is brought into contact with an aqueous palladium-free activation composition in order to obtain by depositing a metal or metal alloy, ie depositing a seed or an activation layer, for Metallized activated surface.

Preferably the method of the present invention (for activation), wherein in step (c) the contact is in the range of 10°C to 90°C, preferably in the range of 14°C to 75°C, more preferably in the range of 10°C to 90°C It is carried out at a temperature in the range of 16°C to 65°C, preferably in the range of 18°C to 45°C, and even optimally in the range of 20°C to 32°C. In particular, preferably in step (c), a temperature in the range of 18°C to 45°C, preferably in the range of 20°C to 32°C, and wherein the reduction by one or more than one reducing agent It is borohydride, preferably sodium borohydride.

Preferably, the method of the present invention (for activation), wherein in step (c), the contacting is carried out in the range of 1 minute to 10 minutes, preferably 2 minutes to 8 minutes, more preferably 3 minutes to 10 minutes. 6 minutes, preferably 3.5 minutes to 5 minutes.

Preferred is the method of the present invention (for activation) wherein step (c) is followed by a rinsing step. In this case, a rinsed activated surface for metallization is obtained. Preferably, rinsing is performed with water.

Preferably the method of the present invention (for activation), wherein the method is carried out for 10 days or more without replacing most of the activation composition (i.e., more than 50% by volume of the composition) in one step, compared to Preferably 50 days or longer, better 200 days or longer, even better 1 year or longer, best 2 years or longer, even better 5 years or longer. Metalization:

The present invention further relates to a method of metallizing the activated surface of a non-conductive or carbon fiber-containing substrate, the method comprising the steps of (A) providing a non-conductive or carbon fiber-containing substrate with an activated surface for metallization obtained by the method of the present invention (for activation), preferably, preferably as defined in the text, (B) metallizing the activated surface by contacting the activated surface with a first metallization solution such that a first metallization layer is deposited on the activated surface.

In step (A) of the method of the invention (for metallization), a non-conductive or carbon fiber-containing substrate with an activated surface as obtained by the method of the invention (for activation) is provided; for details, see above. The foregoing with respect to the method of the present invention (for activation) preferably applies to the method of the present invention for metallization, most preferably, as described.

Preferably the method of the present invention (for metallization), wherein in step (B) the first metallization layer is deposited on the transition metal obtained in step (c) of the method of the present invention (for activation) or different layers on transition metal alloys.

Preferably the method of the present invention (for metallization), wherein in step (B), the first metallization solution is substantially free or free of reversible equilibrium between metal ions and their particles; more preferably substantially is free or free of metal/metal alloy particles, and most preferably is substantially free or free of any particles.

Preferably the method of the present invention (for metallization), wherein in step (B) the first metallization solution contains or does not contain a reducing agent.

Preferably the method of the present invention (for metallization), wherein step (B) is in the range of 10°C to 95°C, preferably 15°C to 85°C, more preferably 20°C to 65°C °C, even better in the range of 25°C to 55°C, most preferably at a temperature in the range of 30°C to 45°C.

Preferably the method of the present invention (for metallization), wherein step (B) is carried out for 30 seconds to 180 minutes, preferably 45 seconds to 120 minutes, more preferably 1 minute to 60 minutes, and most preferably 1.5 minutes to 45 minutes .

It is preferably the method of the present invention (for metallization), wherein in step (B), the first metallization solution does not contain a reducing agent and is an immersion metallization solution, preferably containing palladium ions, platinum ions One or more than one species of ions of the group consisting of , silver ions, gold ions and mercury ions, preferably palladium ions, and preferably palladium ions with a total concentration in the range of 0.05 mg/L to 20 mg/L.

More preferably, the method of the present invention (for metallization), wherein in step (B), the first metallization solution is an acidic palladium impregnated metallization solution.

Preferably, the method of the present invention (for metallization), wherein in step (B), the first metallization solution is an immersion metallization solution containing a total concentration of 0.09 mg/L to 10.0 mg/L range (based on the total volume of metallization solution), preferably in the range of 0.1 mg/L to 5.0 mg/L, more preferably in the range of 0.12 mg/L to 3.0 mg/L, even better in the range of 0.15 mg /L to 2.0 mg/L, preferably in the range of 0.2 mg/L to 1 mg/L, and even optimally in the range of 0.22 mg/L to 0.75 mg/L of palladium ions. This is especially true if the metallization solution is acidic. In combination with the method of the present invention (for activation), such metallization solutions require surprisingly low concentrations of palladium ions compared to known prior art metallization solutions, but in the context of the present invention, without damaging the metal results/quality.

Alternatively, preferably the method of the present invention (for metallization), wherein in step (B) the first metallization solution contains a reducing agent and is an autocatalytic metallization solution, preferably containing one or more than one species The transition metal ions preferably include copper ions and/or nickel ions.

Regardless of the type, however, the first metallization solution is, preferably, a clear solution free of particles.

Preferably the method of the present invention (for metallization) comprises the following steps (A) providing a non-conductive or carbon fiber-containing substrate with an activated surface for metallization obtained by the method of the present invention (for activation), preferably, preferably as defined in the text, (B) metallizing the activated surface by contacting the activated surface with a first metallization solution, the first metallization solution being an autocatalytic metallization solution comprising copper ions and a reducing agent such that a first metallization solution comprising copper or a copper alloy A metallization layer is deposited on the activated surface.

Alternatively, preferably the method of the present invention (for metallization) comprises the following steps (A) providing a non-conductive or carbon fiber-containing substrate with an activated surface for metallization obtained by the method of the present invention (for activation), preferably, preferably as defined in the text, (B) metallizing the activated surface by contacting the activated surface with a first metallization solution, the first metallization solution being an impregnated metallization solution containing palladium ions (preferably as previously described) such that the palladium containing solution a first metallization layer is at least partially deposited on the activated surface, and subsequently (C) metallizing the first metallization layer by contacting the first metallization layer with a second metallization solution such that the second metallization layer is deposited on the first metallization layer.

Preferably, the method of the present invention (for metallization), wherein in step (C), the second metallization solution contains a reducing agent, preferably a reducing agent and nickel ions.

Therefore, preferably the method of the present invention (for metallization), wherein in step (C), the second metallization layer comprises nickel; preferably a nickel or nickel alloy layer.

However, in other cases, the method of the present invention (for metallization) is preferred, wherein in step (C) the second metallization solution comprises a reducing agent, preferably a reducing agent and copper ions.

Therefore, preferably the method of the present invention (for metallization), wherein in step (C), the second metallization layer comprises copper; preferably a copper or copper alloy layer.

In other cases, the method of the present invention (for metallization) is preferred, wherein in step (C), the second metallization solution contains a reducing agent, preferably a reducing agent and cobalt ions.

Therefore, preferably the method of the present invention (for metallization), wherein in step (C), the second metallization layer comprises cobalt; preferably a layer of cobalt or a cobalt alloy.

Preferably the method of the present invention (for metallization), wherein in step (C), the second metallization layer is within 8 seconds to 30 seconds, preferably within 10 seconds to 25 seconds, most preferably within 12 seconds Deposition begins within seconds to 20 seconds. This works best if the second metallization layer contains nickel. Thus, our experiments have shown that the first metallization layer comprising palladium acts as a reinforcing agent for the second metallization layer of nickel or nickel alloys.

The present invention is described in more detail by the following non-limiting examples. Examples provide substrates:

In all experiments, substrates of FR4 (Substrate 1, resin-containing laminate, 5 x 5 cm test panel) or ABS (Substrate 2, plastic, 3 cm diameter test panel) were used. Preprocessing:

Unless otherwise specified, each substrate was treated with a pretreatment solution comprising a nitrogen-containing compound, particularly polyquaternary ammonium 6, for at least 4 minutes at a temperature of about 50°C. Subsequently, the pretreated substrate was rinsed with water. Activating composition and activation:

The substrate is contacted with the activation composition (the composition according to the invention, hereinafter abbreviated AC, and the comparative activation composition, hereinafter abbreviated cAC) for a period of time sufficient to obtain an activated surface for subsequent metallization (contact time) .

The activation composition according to the present invention contains citric acid as a complexing agent. The first species is copper. The total starting volume of each activation composition was about 0.5 L.

Specific and individual parameters and results for the respective activation compositions are summarized in the table below. Each activation composition according to the present invention contains no (ie, is completely free of) palladium, a compound that intentionally prevents oxidation of the copper particles and a stabilizer compound that stabilizes the copper particles and prevents agglomeration. In fact, these activating compositions consist essentially of the ingredients mentioned herein and their reaction products.

First set of examples: Table 1 : Specific and individual parameters of the first set of examples; concentration and molar ratio are initial, ie before first step (c) AC#1 AC#2 AC#3 Cu ²⁺ [mol/L] 0.02 0.02 0.02 Cu ²⁺ [g/L] 1.27 1.27 1.27 Ni ²⁺ [mol/L] -- 0.005 -- Ni ²⁺ [g/L] -- 0.29 -- Citric acid [mol/L] 0.025 0.03 0.05 Citric acid [g/L] 4.8 5.8 9.6 NaBH ₄ * [mL]/[mmol/L] 25/2.6 25/2.6 25/2.6 Molbi Cu ²⁺ : NaBH ₄ 7.6 7.6 7.6 Molar ratio Cu ²⁺ : citric acid 0.80 0.67 0.40 pH 4.8 4.8 4.8 T [°C] twenty two twenty two twenty two Contact time [s] 240 240 240 Substrate 1 FR4 FR4 FR4 Substrate 2 ABS ABS ABS activation Yes Yes Yes Backlight Test [D] 8 to 9 9 7 to 8 *NaBH solution with c = ₂ g/L and containing NaOH

With regard to this first set of examples, in a first step, a starting aqueous solution is provided comprising dissolved copper ions, citric acid, and optionally dissolved nickel ions. The solution was clear and had a typical blue/light blue color.

After the initial amount of NaBH4 (see Table ₁ ) was added at moderate speed with stirring, the boron-containing reducing agent was temporarily present and a portion of the dissolved copper ions were immediately reduced to form copper nanoparticles. Typically, in this initial reduction, not all copper ions are reduced. During reduction, hydrogen gas is formed. When gas formation ends, reduction is substantially complete. After particle formation (approximately 10 nm in size), the starting solution became a colloidal activation composition. The color was dark brown and no precipitated agglomerates were observed. The composition was continuously agitated and continuously contacted with ambient air. Consequently, oxidation of the formed particles is not prevented at all, especially after reduction is complete. The respective activation compositions were further agitated and ready to be used for the first activation while the copper particles were still exposed to oxidation.

Subsequently, step (c) of the method of the invention (for activation) is carried out for the first time. For each substrate, well-adhered copper and copper alloys that could not be removed by rinsing were deposited on the surface of the respective substrate. In each case, the activation was excellent and sufficient for subsequent metallization.

Subsequently, AC#1 to AC#3 were stored under stirring for 2 days (initial +2). An onset of discoloration was observed, ie from dark brown to light brown, with an increase in bluishness. This indicates that the total amount of copper particles decreases and the total concentration of dissolved copper ions increases due to reversible equilibrium. However, repeated activation with AC#1 to AC#3 was successful and achieved a second set of substrates (FR4 and ABS) with very similar backlight results (see below for additional information on backlight testing).

After activation of the second set of substrates, ie after initial +2, ₅ ml of NaBH4 solution (c = 2 g/L) were added to each of AC#1 to AC#3 to reformulate copper particles. A small amount was isolated from samples AC#1 and AC#2 as controls (cAC#1 and cAC# ₂ ) prior to the addition of NaBH4. No NaBH ₄ was added to cAC#1 and cAC#2 and no stirring was applied, so that continuous or semi-continuous oxidation was almost prevented therein. After adding this amount of NaBH ₄ to AC#1 to AC#3, a third set of substrates (FR4 and ABS) with very similar backlight results were successfully activated.

After three days (initial +3), a fourth group of substrates (FR4 and ABS) with very similar backlight results were successfully activated again. Subsequently, 2.5 ml of NaBH ₄ solution (c = 2 g/L) was added to each of the compositions AC#1 to AC#3, and the fifth set of substrates (FR4 and ABS) were successfully activated again with very similar backlight results. After 4 days (initial +4), this procedure was repeated with the sixth and seventh sets of substrates, respectively.

After nine days (initial +9), 10 ml of NaBH4 solution (c = ₂ g/L) was added to each composition AC#1 to AC#3 and the eighth group of substrates (FR4 and ABS) were successfully activated again.

After the addition of NaBH ₄ , the pH eventually increased slightly up to 6 without manual readjustment.

Regarding the control sample, cAC#1 showed light blue/light green and precipitated agglomerates after 5 days (initial + 5 days). After initial +5, cAC#2 appeared blue and was a particle free solution. Basically, such an activating composition can be stored and returned to use after adding another portion of the reducing agent. However, under this condition, activation could not be obtained with it.

As a final result, AC#1 to AC#3 do not additionally require any antioxidant compounds and/or specific stabilizer compounds to prevent coalescence. Rather, these activating compositions remain active over time by maintaining a reversible equilibrium, particularly by maintaining even primarily an oxidative environment.

A test with AC#3, which contained 5.2 mmol/L sodium borohydride instead of 2.6 mmol/L, was again excellent.

Backlight test (metal coverage on substrate surface): Coverage was assessed using an industry standard backlight test in which individual substrates were slit to allow areas of incomplete coverage to be detected as bright spots when viewed under strong light sources (compare US 2008/0038450 A1 and WO 2013/050332) . The quality of the covering is determined by the amount of light observed under a conventional optical microscope. Results are given on the order of D1 to D10, where D1 (little, incomplete coverage) means the worst result and D10 (complete, strong coverage) means the best result.

The second set of examples: In a second set of examples, activation and subsequent metallization were tested. For this purpose, the specific and individual parameters used are summarized in Table 2. The same general parameters as outlined above for the first set of examples apply. Table 2: Specific and individual parameters of the second set of examples; concentrations and molar ratios were initial, ie before the first step (c) AC#4 AC#5 AC#6 AC#7 Cu ²⁺ [mol/L] 0.010 0.010 0.005 0.010 Cu ²⁺ [g/L] 0.65 0.65 0.30 0.65 Ni ²⁺ [mol/L] -- 0.005 0.010 0.0005 Ni ²⁺ [g/L] -- 0.30 0.60 0.03 Citric acid [mol/L] 0.025 0.030 0.030 0.025 Citric acid [g/L] 4.8 5.78 5.78 4.8 NaBH ₄ * [mL]/[mmol/L] 50/5.28 50/5.28 50/5.28 50/5.28 Molbi Cu ²⁺ : NaBH ₄ 1.9 1.9 0.9 1.9 Molar ratio Cu ²⁺ : citric acid 0.40 0.33 0.17 0.40 pH 5.2 5.2 5.2 5.2 T [°C] twenty two twenty two twenty two twenty two Contact time [s] 240 240 240 240 Substrate 1 FR4 FR4 FR4 FR4 activation Yes Yes Yes Yes first metallization layer Cu Cu Cu Cu first metallization layer Not tested Ni Ni Ni *NaBH₄ solution with c = 2 g/L and containing NaOH

Regarding the second set of examples, the contacting according to step (c) of the method of the invention (for activation) is carried out after the preparation of the activation composition.

Subsequently, in a first method, the method of the invention (for metallization) is carried out with a first metallization solution to obtain a first metallization layer. The first metallization solution was an electroless autocatalytic copper plating bath containing copper ions (about 2 g/L Cu ²⁺ ) and aldehyde as a reducing agent, wherein the metallization parameters were as follows: pH 11, 35°C, 20 minutes. After activation, a well-adhered first metallized copper layer covering the entire activated surface was obtained (no jump plating was observed).

In each of AC#4 to AC#7, the reversible equilibrium was maintained by intentionally not preventing oxidation by ambient air. In addition, if necessary, the NaBH4 solution was added semi _- continuously to reformulate the particles. No precipitated agglomerates were observed.

In a second method, FR4 samples activated with AC#5 to AC#7, respectively, were subjected to the method of the present invention (for metallization), using a first metallization solution containing nickel instead of copper to deposit a nickel-phosphorus layer; the metal Chemical parameters: 85°C for more than 5 minutes, pH about 5.0. After activation, it is directly feasible to deposit a nickel phosphorous layer as the first metallization layer.

Typically, boric acid is present at a total concentration of less than 0.2 g/L after preparation of the activation composition (eg, AC#4). To study the effect of boric acid, in addition, AC#4 was used with additional modifications with intentional addition of boric acid to total concentrations of 1 g/L (AC#4-1) and 10 g/L (AC#4-10). In each case the pH was increased to about 5.5. However, no differences were observed in activation and metallization.

The third group of examples: In the third set of examples, NaBH was replaced by dimethylaminoborane (DMAB)₄ Repeat AC#4. As a result, AC#8 was obtained. Other specific and individual parameters are summarized in Table 3. Table 3: Specific and individual parameters of the third set of examples; concentrations and molar ratios were initial, ie before the first step (c) AC#8 Cu ²⁺ [mol/L] 0.010 Cu ²⁺ [g/L] 0.65 Ni ²⁺ [mol/L] -- Ni ²⁺ [g/L] -- Citric acid [mol/L] 0.025 Citric acid [g/L] 4.8 DMAB* [mL]/[mmol/L] 8/27.2 Molbi Cu ²⁺ : DMAB 0.37 Molar ratio Cu ²⁺ : citric acid 0.40 pH 4.0 T [°C] 60 Contact time [min] 30 Substrate 1 FR4 activation Yes copper metallization Yes * DMAB solution, where c = 100 g/L

Activation with AC#8 was performed with or without pretreatment with equal success. However, higher temperatures are required to obtain sufficient activation compared to the example using sodium borohydride.

Also in AC#8, the reversible equilibrium is maintained by intentionally not preventing oxidation by ambient air. In addition, the DMAB solution was added semi-continuously to reformulate the particles, if desired. No precipitated agglomerates were observed.

The fourth group of examples: In the fourth set of examples, other parameters were changed as outlined in Table 4. Table 4: Specific and individual parameters of the fourth group of examples; concentrations and molar ratios were initial, ie before the first step (c) AC#9 AC#10 AC#11 AC#12 AC#13 Cu ²⁺ [mol/L] 0.005 0.010 0.020 0.041 0.610 Cu ²⁺ [g/L] 0.325 6.50 1.30 2.60 3.90 Citric acid [mol/L] 0.025 0.250 0.050 0.100 0.150 Citric acid [g/L] 4.8 48.0 9.6 19.2 28.8 NaBH ₄ * [mL]/[mmol/L] 50/5.28 NaBH ₄ ** [mL]/[mmol/L] 50/10.6 NaBH ₄ *** [mL]/[mmol/L] 50/21.1 NaBH ₄ ^# [mL]/[mmol/L] 50/31.7 NaBH ₄ ^## [mL]/[mmol/L] 50/52.8 Molbi Cu ²⁺ : NaBH ₄ 0.95 0.19 1.89 1.94 19.23 Molar ratio Cu ²⁺ : citric acid 0.20 0.04 0.40 0.41 4.07 pH 5.95 4.62 4.9 5.2 4.8 T [°C] twenty two twenty two twenty two twenty two twenty two Contact time [s] 240 240 240 240 240 Substrate 1 FR4 FR4 FR4 FR4 FR4 activation Yes Yes Yes Yes Yes Cu metallization Yes Yes Yes Yes Yes Backlight Test [D] Not tested 10 10 9 to 10 10 *NaBH₄ Solution, c = 2 g/L and contains NaOH, **NaBH₄ solution, c = 4 g/L and contains NaOH, ***NaBH₄ Solution, c = 8 g/L and contains NaOH,^# NaBH₄ Solution, c = 12 g/L and contains NaOH,^## NaBH₄ Solution, c = 20 g/L and contains NaOH

Also in AC#9 to AC#13, a reversible equilibrium was maintained by intentionally not preventing oxidation by ambient air and if necessary a reducing agent was added semi-continuously to reformulate the particles. No precipitated agglomerates were observed. Excellent activation of FR4 was obtained, and backlight test results were excellent.

Fifth group of examples: In the fifth group of examples (details not shown), the activation composition according to the present invention comprising 0.005 mol/L Cu ²⁺ , 0.05 mol/L citric acid and 1.3 mmol/L sodium borohydride was used Activation was tested on FR4 and ABS. Again, fully activated FR4 and ABS were obtained with excellent backlight test results.

Sixth set of examples: In a sixth set of examples (details not shown), carbon fiber-containing felts (4.6 mm thick; Activation was tested on approximately 450 g/m ² areal weight, BET surface area 0.4 m ² /g). Likewise, fully nickel-activated felts were obtained in each case. Furthermore, these activated surfaces exhibit significant catalytic activity in electrolysis to form hydrogen and oxygen.

Claims (15)

A method of activating the surface of a non-conductive or carbon fiber-containing substrate for metallization, the method comprising the steps of: (a) providing the substrate, (b) providing an aqueous palladium-free activation composition comprising (i) Dissolved transition metal ions and metal particles thereof of the first species, (ii) one or more than one complexing agent, (iii) one or more than one reducing agent, permanently or temporarily, (iv) optionally different from the first Dissolved metal ions of one species or more than one second species, wherein- at least the first species, the dissolved transition metal ions and their metal particles are present in reversible equilibrium, with the proviso that- the metal particles are Formed from the dissolved transition metal ions by continuous or semi-continuous reduction of the one or more than one reducing agent, - the dissolved transition metal ions are formed from metal particles by continuous or semi-continuous oxidation of the particles, and - the dissolved transition metal ions and their metal particles are repeatedly involved in the reduction and the oxidation, respectively, so that precipitation agglomerates of the metal particles are not formed, (c) contacting the substrate with the activating composition such that the transition A metal or transition metal alloy is deposited on the surface of the substrate and an activated surface for metallization is obtained. The method of claim 1, wherein during and/or after step (c), a majority of the metal particles are subjected to the oxidation. The method of claim 1 or 2, wherein the first species is copper or cobalt. The method of claim 1 or 2, wherein the metal particles of the first species in the activation composition are colloidal metal particles. The method of claim 1 or 2, wherein the other metal particles of the first species are continuously or semi-continuously formed in situ on the activation by the reduction after and/or during one or more than one step (c) is performed in the composition. The method of claim 1 or 2, wherein the one or more than one reducing agent comprises a boron-containing reducing agent. The method of claim 1 or 2, wherein the activation composition is substantially free or free of tin ions. The method of claim 1 or 2, wherein the activation composition is substantially free or free of compounds that prevent oxidation of the metal particles and/or is substantially free or free of stabilizer compounds that stabilize the metal particles . The method of claim 1 or 2, wherein the one or more than one reducing agent is continuous or semi-continuous Continuously added to the activation composition such that the dissolved transition metal ions from the first species, respectively, form other metal particles continuously or semi-continuously. The method of claim 1 or 2, wherein the dissolved transition metal ions are formed from the metal particles by oxidation of ambient air and/or oxygen. The method of claim 1 or 2, comprising a pretreatment step of the substrate prior to step (c): (a-1) treating the substrate with a pretreatment solution comprising a nitrogen-containing compound. A method of metallizing the activated surface of a non-conducting or carbon fiber-containing substrate, the method comprising the steps of: (A) providing a method for activation obtained by the method for activation as claimed in any one of claims 1 to 11 with Metallizing the non-conductive or carbon fiber-containing substrate of the activated surface, (B) metallizing the activated surface by contacting the activated surface with a first metallization solution such that a first metallization layer is deposited on the activated surface . A method of preparing an aqueous palladium-free activation composition for activating the surface of a non-conductive or carbon fiber-containing substrate for metallization, the method comprising the steps of: (1) providing an aqueous starting solution comprising - a first Solubilized transition metal ions of species, - one or more than one complexing agent, and - as desired, one or more than one solubilized second species different from the first species dissolved metal ions, (2) continuously or semi-continuously adding one or more than one reducing agent to the starting solution such that at least one of the dissolved transition metal ions of the first species is continuously or semi-continuously formed in the solution, respectively A metal particle, provided that the metal particle is continuously or semi-continuously oxidized to form dissolved transition metal ions of the first species. Continuous or semi-continuous reduction of dissolved transition metal ions of a first species is combined with continuous or semi-continuous oxidation of metal particles of the first species in reversible equilibrium to continuously or semi-continuously in an aqueous palladium-free activation composition. The purpose of forming metal particles in situ. An aqueous palladium-free activation composition for activating the surface of a non-conductive or carbon fiber-containing substrate for metallization, the composition comprising (i) dissolved transition metal ions of a first species and metal particles thereof, ( ii) one or more than one complexing agent, (iii) one or more than one reducing agent, permanently or temporarily, (iv) one or more than one reducing agent, as desired, a dissolved metal ion other than one of the first species or more than one second species , wherein - at least the first species, the dissolved transition metal ions and their metal particles are present in reversible equilibrium, with the limitation that - the metal particles are derived from the dissolved transition metal ions by the one or more The continuous or semi-continuous reduction of a reducing agent forms, - the dissolved transition metal ions are formed from the metal particles by continuous or semi-continuous oxidation of the particles, and - the dissolved transition metal ions and their metal particles repeatedly participate in the reduction and the oxidation, respectively, so that no Precipitated agglomerates of the metal particles are formed.