EP0087135A1

EP0087135A1 - A powder for use for dry activation of a substrate for electroless metallization

Info

Publication number: EP0087135A1
Application number: EP83101561A
Authority: EP
Inventors: Gunnar Sorensen; Leo Gulvad Svendsen
Original assignee: LK POWER SYSTEMS AS; Neselco AS
Current assignee: Cessione platonec Aps
Priority date: 1982-02-18
Filing date: 1983-02-18
Publication date: 1983-08-31
Also published as: FI833778A0; AU1163183A; FI73243C; EP0087135B1; FI73243B; DK70582A; FI833778A; NO833723L; DK153572C; JPS59500221A; DE3367628D1; CA1212660A; DK153572B; WO1983002960A1; NO160452B; ATE23572T1; AU556818B2; IL67963A; IE55891B1; NO160452C

Abstract

A catalytically active powder, its preparation, and its use for activating insulating substrates to receive electrolessly deposited metal in a coherent metal layer are described. The powder of the invention comprises a plastic powder containing catalyzing/activating chemical compounds allowing that the acceleration of the catalyst is not carried out until the powder is melted down onto the substrate. The substrate need not be etched prior to the metallization since the plastic melted down ensures a good adhesion between metal and plastics and between plastics and substrate. Furthermore, the colloidal nature of the catalyzing compounds is stabilized in a particular and especially durable manner by the plastic powder. The use of the powder causes less risk to the environment since the catalyst may be applied as a dry powder, and since the etching of the substrate is avoided.

Description

The invention relates to a catalytically active powder, its preparation, as well as a method using said powder to make insulating substrates active for receiving electrolessly deposited metal in a coherent metal layer.
Catalytically active powders directly suitable foractivat- ing a substrate for electroless metallization were not known previously.
In deposition of metal on insulating substrates such as for instance plastics, the following methods may be employed: deposition of metal under vacuum, application of conductive paints followed by electrolytical metal deposition as well as electroless metallization, the latter in addition possibly being followed by an electrolytical metallization.
Electroless metallization has gained a widespread use within electrotechnics as well as for metallizing finished plastics. A disadvantage of the known methods for electroless metallization is the series of wet process steps used within the commercial utilization in order to achieve a sufficient adhesion of the metal layer to the surface of the substrate. The process steps are frequently carried out in the following sequence: Etching, neutralizing, sensibilization, activation, acceleration, and electroless metal deposition. In a great number of processes, sensibilization and activation constitute one process step since the purpose thereof is to situate the catalyzing seeds on the surface of the substrate, said seeds catalyzing the metal deposition from the bath in a metallizing bath. Such a catalyst sensitizes and activates an insulating surface for electroless metallization in one step and consists for instance of a mixture of SnCl₂ and PdCl₂, the so-called palladium-tin system. This system usually includes an aqueous solution of a colloidal nature since it is important to stabilize the system as precipitation reactions otherwise occur involving aging and destruction of the catalyzing effect.
The patent literature refers to both organic and aqueous solutions, which by influencing an insulating substrate may make said substrate receptive to electroless metal deposition. Danish printed accepted specification No. 132,801 describes how a compound of an element from group 8 or 1B of the periodic system or mixtures thereof in an oraanic solvent,which in addition may contain an adhesive, may wet a substrate and make it catalytically active. German Offenlegungsschrift No. 26 36 457 also states an aqueous catalytic lacquer for the production of printed circuits and comprising a binder, a metal compound, a complex builder, and a reducing agent. Upon the application and drying¡ said metal compound is present as metal seeds which may be additionally reinforced through electroless metallizing. Aqueous solutions have previously been encumbered with the draw-back that hydrophobic plastic substrates can only be wetted with difficulty. This feature was especially recognized by the so-called two-step process with separated sensibilization and activation steps, cf. e.g. US patent specification No. 4,042,730, or more detailed "Metallic Coating of Plastics" . by William Golde, Vol. I, especially Chapter V. The Danish patent applications _Nos. 1507/79, 4277/80, and 3300/81 state a method and powders for a dry sensibilization of the surface of an insulating substrate possessing several advantages compared to the state of the art, inter alia concerning the distribution of the adhesion of the metal and concerning reduced expenses by the metal deposition. It should in this connection be stated that the sensibilization is a process step in which a chemical "sensitizer" is applied to the surface of a substrate. This chemical compound provides good adherence for an activator/catalyst to the substrate which is deposited'in a galvanic process by contact with an aqueous solution containing said activator/catalyst.
Another manner of making substrates catalytically active for electroless metal deposition includes adhering solid particles to the surface of the substrate, said solid particles being catalytical towards electroless metal deposition. Most suitable are the systems including particles of a colloidal nature, and systems are known including precious metals, as well as other systems having an effect with non-precious metals. The aqueous SnCl₂/PdCl₂ catalyst is the most frequently used since a reasonable stability of the aqueous solution is obtainable. US patent specification No. 3,011,920 describes a process for preparing such a colloidal catalyst, which before the use is accelerated through addition of acid or base. Solid catalyst mixtures - used for the preparation of an optically transparent liquid - have been described in US patent specification No. 3,672,923. Such systems are generally encumbered with the problem of a lacking long-term stability, and the literature within the field describes aging effects and the importance of the use of an accelerator solution. Within electroless metallizing, an accelerator solution means a solution of chemicals with an acid or alkaline reaction, the influence of which on the activated substrate promotes the initiation of an electroless metal deposition. In the present connection, the catalyst solution may in addition have an activating effect on the catalytic powder melted down, which corresponds to the fact that the catalyst solution in the hitherto known commercial utilization is activated before use through addition of a chemical. There is still doubt about the actual functioning of these systems, and a discussion thereof appears inter alia from "An Electon Diffraction Study on Mixed PdCl₂/SnCl₂ Catalysts for Electroless Plating" by T. Osaka et al. in Jour. Electrochem. Soc.', Nov. 1980, p 2443ff and "A Study on Activation and Acceleration by Mixed PdCl₂/SnCl₂ Catalysts for Electroless Metal Deposition" by R. Zeblenski in the same journal, December 1980, p 2652ff.
It has long been desired to obtain an improved stability of the PdCl₂/SnCl₂ catalysts which have gained a widespread use for processes within electrotechnics, cf. inter alia US patent specification No. 4,187,198 and US patent specification No. 4,212,768. Regarding the effect of these cata- . lysts it is considered probable that the precious metal (e. g.Pd) in the elemental form is stabilized by tin compounds in the solution.
As described in US patent specification No. 3,993,799 it has turned out that systems including colloidal particles of non-precious metals are also catalytic for electroless metal deposition when appropriate baths are employed. It has in connection with such systems been difficult to obtain a high catalytic activity simultaneously with a good stability. US patent specification No. 3,958,048 describes how the colloidal nature could disappear in less than 24 hours. US patent specification No. 4,167,596 describes the use of hydro-oxides understood as a mixture of oxides and hydroxides of cobalt, nickel, iron, copper, and mixtures thereof while adding stabilizers, surfactants, and reactivity-modifying compounds. Upon immersion of the substrate into such a col- loidal system, following rinsing a further immersion is carried out in a solution with a reducing compound. Apart from the wetting of the substrate such a process has the drawback that it cannot be carried out selectively. It has been decribed in the patent literature how an improved adhesion can be obtained, cf. inter alia US patent specification No. 4,233,344, wherein hydrazine hydrate is used as adhesion-improving agent. A change of the pH in the colloidal system, cf. US patent specification No. 4,220,678, changes the charge on the colloidal particles, which has an influence on the adhesion of said particles to the substrate.
It is the object of the invention to provide a powder for use for dry activation of a substrate for electroless metallization which after being melted down in a prescribed pattern on the substrate results in improved adhesion between the colloidal, catalyzing/activating systems and the insulating substrate.
It is a further object of the invention to provide a powder of the type mentioned above which contains the catalyzing/ activating chemical compounds for use in electroless metallization in a very stable form.
These objects are achieved by the powder according to the invention which is characterized in that it comprises fine-grained particles of a plastic material and at least one chemical compound which is a catalyst for electroless metallization, as well as a surfactant, whereby said chemical compound and said surfactant are present in an amount of 0.2 - 20 % by weight and 0.01 - 10 % by weight, respectively, both parts being calculated on the plastic material. Preferably the catalytically active chemical compound is contained in the powder in an amount of 1 to 5 % by weight and the surfactant in an amount of 0.1 to 1 % by weight.
After being melted down onto a substrate and if desired after a suitable acceleration step the substrate can be electrolessly metallized. The use of the powder according to the invention results in a metal layer adhering very well to the melted down plastic powder and showing limits (meaning edges or borders) which are well defined by the distribution (pattern) of the melted down plastic powder.
Claim 2 deals with catalytically active compounds which have proved particularly suitable as ingredients of a powder active for electroless metallizing.
Claim 3 deals with hydro-oxides of metals capable of activating for electroless metallizing when unstable metallizing baths may be used.
Claim 4 deals with a commercial catalyst of the PdCl_2/SnCl₂ type which may be used as an ingredient in a powder according to the invention.
Claim 5 deals with a powder where the active chemical compounds for electroless metallizing have been dispersed in the plastic material as colloidal particles.
Claim 6 deals with a composition of a surfactant which as an ingredient in the powder ensures a good contact with the metallizing bath, whereby a coherent metal layer is obtained.
Claim 7 indicates that a magnetic material may be incorporated into the powder in such a manner that the powder may be transferred magnetostatically or charged electrostatically in a controlled manner by means of a magneticbrush arrangement.
Claim 8 deals with a method for the preparation of the powder according to the invention, said method ensuring a homogenous distribution of the catalytically active compounds on each powder particle.
Claim 9 indicates that the plastic suspension is spray dried, whereby a powder having a uniform particle size is obtained.
Claim 10 states that prior to the drying of the plastic suspension, a reducing compound is added, the reaction of said reducing compounds with the catalytically active compounds improving the deposition of metal.
Claim 11 states that the powder melted down onto a substrate is treated in a salt-acid or alkaline medium with the purpose of improving the deposition of metal and obtaining an improved adhesion of the metal to the plastic powder melted down.
Claim 12 states that the powder is suitable for obtaining metallizing of an insulating substrate.
Claim 13 indicates that the powder is electrostatically transferable to a substrate.
Claim 14 states that magnetic compounds built in may ensure a magnetostatic transfer. 5
The powder according to the invention comprising a plastic powder which contains the well-known PdCl₂/SnCl₂ catalysts or another precious metal catalyst of colloidal nature or hydro-oxides of non-precious metals as well as a sur-0 factant, has the advantage that after melting down the powder onto a substrate and suitable acceleration, metallization of the substrate with a good adhesion of the deposited metal and sharp metallizing limits becomes possible.
Such a powder provides an essential improvement compared to 5 the prior art. Thus the stability of the catalyzing compounds has been considerably increased, not the least due to the fact that the acceleration is not being carried out until the powder has been melted down onto the substrate, contrary to the conventional wet process where acceleration of the catalyst is carried out prior to immersion of the substrate into the solution or suspension of the catalyst. It has not previously been recognized that by using catalysts in the form of catalyzing plastic powder, whether said powder contains precious metal systems or non-precious metal compounds, considerable advantages can be obtained. For instance etching of the substrate in order to form cavities in which the catalyzing compound may be sucked up so as to ensure a good adhesion is avoided. Furthermore,the colloidal nature of the catalyzing compounds is stabilized in the powder according to the invention in a particular manner by the use of a fine-grained plastic powder.
The catalytic compounds in the powder according to the invention may include any desired compound of the metals from group VIII of the periodic system, for instance iron, cobalt, nickel, ruthenium, rhodium, palladium and/or iridium, in addition to a tin compound, the tin compound to as large an extent as possible being present in the oxidation number +2 or in addition to another reducing compound of inorganic or organic nature. Alternatively, the catalytically active compound may be a compound of a metal from group IB of the periodic system, as copper, silver or gold.
When the catalyzing compounds are complex compounds, it may be necessary to use an accelerator for the metallization which accelerator may be an acid or an alkaline substance. When commercial catalysts of the PdCl₂/SnC'₂ type are used, an aqueous hydrochloric acid solution (conc. HC1 to H₂0 e.g. 1:2) is a suitable accelerator. In this manner the stabilizing alkaline halides are removed from the melted down catalyzing powder, whereby a more water permeable surface is achieved in addition. At the following metallization process, this increased surface porosity causes an extremely good adhesion of the metal to be deposited to the melted down plastic powder.
For the preparation of a powder according to the invention including an Sn-Pd catalyst it may under certain circumstances be undesired that alkaline halides are used to form a complex compound with PdCl₂, since this can result in a very fatty powder. However, U.S. patent specification No. 4,212,768 states that other halides are applicable, e.g. CaCl₂·6H₂O, and LaCl₃·7H₂O. It was found particularly advantageous for a powder according to the invention to utilize a double salt of CaCl₂·6H₂O and PdCl₂, since a very electrostatic powder is thereby obtained. Another manner of avoiding undesired properties of the powder including a conventional Sn-Pd catalyst, such as e.g. 9F from Shipley Corp., is to use a plastic emulsion in stead of a jet-ground powder. In this manner the concentration of the double salt is reduced, said double salt containing the catalytically active metal.
In the field of conventional electroless metallization, surfactants have usually been added to the baths used. It was not previously recognized that an improved effect can be obtained if the powder which is capable of activating the surface of a substrate for electroless metallization includes a surfactant. The hydrophobic part of this surfactant adheres to the hydrophobic plastic material being the main ingredient of said powder, whereas at the same time the hydrophilic part of the surfactant ensures a good contact between the melted down powder and an aqueous medium.
Especially in case of the use of a commercial catalyst of the PdClZ/SnClz type the invention brings about an important advantage because said catalyst is not activated for electroless metal deposition until the powder according to the invention has been melted down and the substrate with the melted down powder is treated, if necessary, with an acid or alkaline medium. As a result, both the powder and the plastic film formed of said melted down powder demonstrate a durability not previously known.
A method for the preparation of a powder according to the invention includes the steps of mixing the plastic material in fine-grained form or prepared by an emulsion polymerisation in an aqueous medium with an aqueous dispersion of a surfactant, whereafter the catalyzing compounds are added and dried upon adjustment of the desired pH value, e.g. through spray drying. The method according to the invention is characterized in that it is carried out in an aqueous medium, and that the colloidal particles present therein or precursors for such particles, inter alia as a consequence of the influcence of the surfactant, adhere strongly to the plastic particles which act as stabilizer as well as a cement during the melting down of the dry powder, said cement binding the activating/catalyzing compounds for the electroless metallization to the surface of the substrate. The aqueous medium furthermore has the advantage that partly hydrolysed and oxide-containing compounds are present, which on heating, for instance during the spray drying process, are melted in the surface of the powder particles and thereby improve the wetting characteristics of the melted down powder.
The preparation of a powder according to the invention including non-precious catalyst compounds may be carried out on the basis of commercially available solutions with stabilizers present therein and which may be accelerated in a suitable manner, or the colloidal particles may be precipitated prior to the drying process through the addition of reducing surface active and precipitating reagents. At the subsequent drying process, the colloidal nature is in a particular manner stabilized-on the surface of each powder grain as islands of catalytically active compounds.
The powder according to the invention may be applied to an insulating substrate through sprinkling, electrostatic or magneto= static transfer directly to the substrate or via a light-sensitive master, cf. the prior art. The powder is melted down in order to obtain a suitable adhesion to the substrate. If the catalyzing compounds are so stable that they cannot directly iniate an electroless metallizing, an acceleration can be carried out., Such an acceleration may include treating the powder melted down
on the substrate in an acid or alkaline medium. As a result the catalyzing compounds are made active for electroless metallizing. In addition, a more porous structure is obtained, which additonally improves the adhesion of the electrolessly deposited metal. With a later- galvanic process it is possible to increase the thickness of the metal layer.
Within the neighboring field, photocopying, the magnetic one-component toners have gained increasing use. For use in equipment using this principle, it is possible to prepare a powder which in accordance with claim 7 includes a magnetic material in each powder particle, e.g. oxides of iron, the particle size of which is usually less than 2.5 µ. In addition it is possible to precipitate a thin layer of palladium on these grains of magnetic material, e.g. by reducing a palladium salt dissolved in a slurry of said grains onto their surface, e.g. by addition of formaldehyde. Whether these grains of magnetic material have a thin layer of palladium on the surface or not or are commercial powders such as for instance Bayferrox 8600 (Bayer Chemie), a powder according to the invention can be prepared, which in each powder grain includes grains of magnetic material. It is most advantageous that these grains are slurried in a plastic can- sion, to which one or more of the catalytically active compounds as well as a surfactant are added, said surfactant improving the hydrophilic properties of the ponder prepared when said powder is melted down onto an insulating substrate.
The particulate plastic material used in the powder of the invention may be any polymer resin having appropriate surface characteristics as known in the art. Preferred plastic materials are styrene/acryl-copolymer resins, but for example polyester resins, polyimide resins or ABS-resins may equally be used.
The invention thus provides a catalytically active powder which can be used directly to initiate electroless metallization, and which shows the advantage of achieving a good adhesion to the substrate as well as a pore-free merging.
The stability of the powder prepared has proved to be surprisingly good, and it is of great environmental importance that using the powder according to the invention a catalyst for electroless metallization is applied in form of a stable powder in stead of liquids detrimental to environment.
For further explanation of the powder according to the invention, its preparation and use, the following examples are given:

Example 1.

A powder including the following ingredients

Example 2.

A powder as stated in Example 1 is prepared by 100 g of plastic material (Piccolastic D 125) upon crushing being ground on a Trost jet mill. The finely ground powder is slurried in an aqueous dispersion containing the surfactant in an amount corresponding to 0,4%by weight of the plastic material. 5 g of SnCl₂· 2H₂0 are weighed out and heated to 95°C, whereafter 0.1 g of PdCl₂ is added. Upon cooling this mixture is crushed and dissolved in water, whereafter this solution is added to the plastic suspension. Upon adjustment of the pH to 8 by means of ammonia water, the plastic suspension is dried on a spray drier (NIRO Atomizer model Minor) with a rate of rotation on the atomizer wheel of 35,000 r.p.m. and with a feeding velocity and supply of hot air adapted in such a manner that the input temperature and the output temperature werel80°C and 80^oC, respectively.

Example 3.

A powder including the following ingredients:

Example 4.

A powder as stated in Example 3 is prepared by 100 g of Piccotoner.1200 upon crushing being added to an aqueous dispersion containing 0.3 g of Atmer 122, which is a surfactant, in 1 liter of liquid. An amount corresponding to 5 g of solid matter of Catalyst 9_F, which is a commercial catalyst of the PdCl2/SnCl2 type produced by Shipley Inc.,. is diluted into a volume of 1 liter and pH is adjusted by means of a 6 N NaOH solution to about 6. Under heavy stirring the diluted catalyst solution is added to the plastic suspension. By 6N NaOH pH is adjusted to 7, and the mixture is dried on a spray drier (NIRO Atomizer model Minor) with a rate of rotation on the atomizer wheel of 35,000 r.p.m. and a feeding velocity and supply of hot air adapted in such a manner that the input temperature and the output temperature were 180°C and 80 C, respectively.

Example 5.

The use of powder as stated in Example 3 is performed by applying it to an insulating substrate completely or partly, the powder being sprinkled through a serigraphic mask, transferred electrophotographically or in another manner, whereafter it is melted down at a temperature of 140°C. The substrate with the powder melted down is immersed into a solution of concentrated hydrochloric acid and water in the ratio 1:3 for a period of 8 minutes. Subsequently it is treated in an accelerator solution (Shipley 19H) for 3 minutes in order upon rinsing to be metallized in a Shipley 328 electroless copper bath at room temperature.

Example 6.

A powder including the ingredients

Example 7.

A powder including the ingredients

Example 8.

A powder as stated in Example 6 is prepared by 100 g of plastic material upon crushing being ground on a Trost jet mill. The finely ground powder is slurried in an aqueous dispersion containing the surfactant (Atmer 114) in an amount corresponding t00,3% by weight of the plastic material. An aqueous solution of the metal salt is added in the desired amount, whereafter pH is adjusted to 8 by 6N NaOH. Subsequently, the plastic suspension is dried on a spray drier (NIRO Atomizer model Minor) with a rate of rotation on the atomizer wheel of 35,000 r.p.m. and a feeding velocity and supply of hot air adapted in such a manner that the input temperature and the output temperature were 170°C and 70°C, respectively.

Example 9.

Analogous with Example 8, a powder as stated in Example 7 was prepared.

Example 10.

A powder of a plastic material containing hydro-oxides of a metal present in one or more oxidation steps was prepared by 100 g of plastic material (Piccotoner 1200) being slurried in a dispersion of a surfactant (Atmer 122 from ICI-Atlas), the amount of which corresponded to0,3% by weight of the plastic powder. An aqueous solution was admixed which contained 8 g of CuCl₂, and during heavy stirring an aqueous solution of 2g of KBH₄ was additionally added, whereafter a 6_{N N}aOH solution was added until a pH of about 9 was reached. The resulting plastic suspension was dried on a spray drier (NIRO Atomizer model Minor) with a rate of rotation on the atomizer wheel of 35,000 r.p.m. and a feeding velocity and supply of hot air adapted in such. a manner that the temperature and the output temperature were 200°C and 80°C, respectively.

Example 11.

An aqueous plastic emulsion (Dresinol from Hercules _Inc.) corresponding to 100 g of solid matter was added to an aqueous dispersion of 0.3g of surfactant (Span 60 from ICI-Atlas). During heavy stirring 30 g of Fe₃O₄ of a particle size of less than 0.5 p were added to the above. Furthermore an aqueous solution of Catalyst 9F (Shipley Inc.) was added in an amount corresponding to 4% of solid matter, and the pH was adjusted to 8 by 6N NaOH, whereafter a spray drying was carried out on a NIRO Atomizer model Minor with a rate of rotation on the atomizer wheel of 35, 000 r.p.m. and a feeding velocity and supply of hot air adapted in such a manner that the input temperature and the output temperature were 160°C and 65°C, respectively.

Example 12.

A powder including the following ingredients

Example 13.

A method for the preparation of a powder as stated in Example 12 included the following steps: 0.4 g of PdCl₂ were dissolved in 2.8 g of CaCl₂ 6H₂O, which were kept melted at 95°C. After 15 minutes 2.8 g of SnCl₂· 2H₂0 were added. This solution was now added to a plastic suspension, where 100 g of Piccotoner 1200, which in avance had been jet-ground, were slurried into 500 ml of distilled water, wherein 300 mq of surfactant Atmer 121 (ICI-Atlas) were dispersed. Thealkali- nity was adjusted to pH = 8 by 6_N NaOH, and a NIRO Atomizer model Minor was used for the spray drying. The atomizerwheel was adjusted to 35,000 r.p.m., and the feeding velocity and supply of hot air were adjusted in such a manner that the input temperature and the output temperature were 180°C and 80°C, respectively.

Example 14.

A powder as'prepared by the method described in Example 11 was transferred in a device for photocopying, whereby powders containing magnetic matter are electrostatically transferred to a light-sensitive master, said master optionally being a polyester film coated with a light-sensitive material. A picture obtained electrostatically by illumination on the light-sensitive surface charged to a positive high voltage of 2.8 kV was produced by said powder by means of a conventional magnet brush arrangement kept at ground potential. Transfer of the resulting electrostatic picture to an insulating substrate was carried out by charging said substrate.

Example 15.

A powder as prepared by the method described in Example 11 was used for developing a magnetically structured Cr0₂-coated polyester film, on which a magnetostatic picture was produced by illumination with a Xenon-flash lamp. During this procedure, said CrO₂-coated magnetized film was illuminated through a photographic film where the light penetrated the bright areas of the film and heated the magnetized film to more than its Curie point. The developing was carried out by a "powder cloud" technique (powder cloud in flow of air). The powder grains adhering to the magnetized film were subsequently transferred to an insulating substrate by said substrate being brought to a positive potential of about 20 kV.

Example 16.

Powders as stated in Examples 1, 3, 6, 7, and 11 were in turn transferred electrostatically as follows: The powder was charged electrostatically to a voltage of 2.2 kV in a conventional device for electrostatic powder transfer. By means of a flow of air the powder was transferred to a substrate whereafter it was melted down by heating to the melting temperature.

Example '17.

A powder with a composition as stated in Example 12 and prepared as stated in Example 13 was mixed in the weight ratio 2 to 100 with iron powder of a particle size of 50 to 100 µ (a conventional carrier for use in magnet brushes). By such a developing mixture in a conventional magnet brush arrangement, latent electrostatic pictures were developed 'on a photo-sensitive master, which through conventional corona-discharge had been charged to a negative high voltage of 3.2 kV and subsequently illuminated selectively by means of a pattern. Transfer from said photo-sensitive master was carried out by charging an insulating substrate so that the particles were transferred by attraction. In a conventional manner the particles were fixed to the isolating substrate and electroless metallizing was carried out.

Claims

1. A powder for use for dry activation of a substrate for electroless metallization, characterized in that it comprises fine-grained particles of a plastic material and at least one chemical compound which is a catalyst for electroless metallization, as well as a surfactant , whereby said chemical compound and said surfactant are present in an amount of 0.2 - 20 % by weight and 0.01 - 10 % by weight, respectively, both parts being calculated on the plastic material.

2. A powder as claimed in claim 1, characterized in that the catalytically active compounds are compounds of the metals of group VIII of the periodic system, such as iron, cobalt, nickel, ruthenium, rhodium, palladium, iridium, in addition to a tin compound containing tin in the oxidation number +2.

3. A powder as claimed in claim 1, characterized in that the catalytically active compounds are compounds of iron, cobalt, nickel, copper, and silver, said compounds being present as hydro-oxides understood as mixtures of hydroxides and oxides.

4. A powder as claimed in claims 1 - 2 , characterized in that a commercial one-component catalyst of the PdCl₂/SnCl₂ type is used as catalyzing compound.

5. A powder as claimed in claims 1-4, characterized in that the plastic material is a styrene/acryl-copolymer resin, the catalyzing compound being colloidal particles dispersed in said plastic material.

6. A powder as claimed in claims 1-5, character-ized in that the surfactant consists of a mixture of glycerolmonostearate and glyceroldistearate, said mixture constituting 0.1 to 1 % by weight of the plastic material.

7. A powder as claimed in claims 1-6, characterized in that it additionally contains a fine-grained magnetic material.

8. A method for the preparation of a powder as claimed in claims 1-7, characterized by mixing the plastic material in finely divided form or prepared through emulsion polymerisation in an aqueous medium with an aqueous solution or dispersion of 0.01 - 10 % by weight of at least one surfactant, calculated on the amount of plastic material, adding the catalyzing compund or compounds in an amount of 0.2 - 20 % by weight, calculated on the amount of plastic material, and drying the completed mixture upon adjustment of the desired pH value.

9. A method as claimed in claim 8, characterized in that the drying is carried out through spray drying.

10. A method as claimed in claims 8-9, characterized in that a reducing agent is added to the catalyzing compounds before the drying.

11. The use of a powder as claimed in claims 1-8, characterized in that the powder upon melting down onto a substrate is subjected to an acceleration treatment in an acid or alkaline medium.

12. The use of a powder as claimed in claims 1-8 and-11, characterized in that the entire surface of the substrate or the part which is desired to be metallized is provided with the powder, which upon melting down and acceleration is metallized through a subsequent electroless metallization known per se.

13. The use as claimed in claim 12, characterized in that the powder is electrostatically transferred to a substrate.

14. The use as claimed in claim 12 of a powder as claimed in claim 7, characterized in that the powder is applied to the substrate magnetostatically under the influence of magnetic poles provided on the substrate in advance.