DE19538531A1 - Process for the deposition of metal layers - Google Patents

Description

The invention relates to a supplementary method for deposition Low-carbon and low-oxygen metal layers due to volatile decomposition metal connections on electrically non-conductive substrate surfaces according to patent application P 44 38 791.1.

The adhesive metal coating of electrically non-conductive substrates for example of plastics, creates considerable problems in many cases me. In particular, a full-surface and double-sided metal coating Of plastic films often fails because the metal layers if the thermal load on the substrate / metal composite is too high easily peel off again. This disadvantage arises in particular with diversi against epoxy resin substrates and in some manufacturing processes for coated polyimides.

Epoxy resin, fluoropolymers, thermoplastics in general and Polyimides have long been used as a substrate material in the electronics industry  strie for the production of printed circuit boards, hybrid circuits, semiconductor bear (chip carrier, multi-chip modules) and other components used. Polyimide has many advantages. For example whose mechanical resistance is higher, so that the linear expansion of the material under thermal stress is less than with other coating materials. Furthermore, polyimide substrates have bes our electrical insulation values.

For use as a substrate material in semiconductor carriers, Vorpro products of the polyimide on a suitable support by a spin coating Process applied in a thin layer and then to polyimide be implemented. In the layers formed in this way, simple and reproducibly finest holes can be etched to connect several Metallization levels serve.

For the production of polyimide laminates, for example for the printed circuit board in the past, mostly copper foils were not used Sheer polyimide films used. The copper layers become the Conductors mostly formed by etching processes. This will be procedural techniques used in the literature (for example in the manual of printed circuit board technology, ed. G. Herrmann, volume 2, Eugen G. Leuze Verlag, Saulgau 1991). Such methods are used to manufacture of printed circuit boards is basically suitable, but the width is finest conductor tracks that can be reproducibly produced with such techniques in the range of about 100 µm. The copper foils are more traditional Way connected by gluing to the polyimide surfaces. However softens the adhesive layer during thermal treatment, for example when soldering the circuit boards, and is also opposite to the chemical ones Baths for the metallization of holes in the polyimide laminates are used, not sufficiently resistant.  

To avoid the adhesive layers, the expert was familiar "Cast-on" technology for the production of adhesive-free polyimide laminates in the liquid polyamic acid solution before dehydration and cyclization to polyimide is poured onto a copper foil. After the polyimide has formed on the copper foil, it is formed on it Way an adhesive polymer / metal composite.

However, this method has the disadvantage that only relatively thick, for example 17 µm thick copper foils can be used. Furthermore are these foils are extremely expensive.

Polyimide laminates coated with thinner copper foils were indeed already made; however, the effort involved in making these laminates extremely high and therefore the prices are also considerable. The handha Exercise of the laminates coated with thin copper foils is above problematic because the copper foils are very sensitive to mecha nical influence. In the case of the "cast-on" technique, such thin copper foils are not used at all because the lami would strongly discard nat in the manufacture.

Finer conductor tracks can therefore only be generated by the fact that none with Laminates with copper foils on the surface as starting material lien can be used. In this case, the conductor tracks are created by Me tall deposit formed directly on the surfaces. By sputtering or Metal evaporation or kle. Manufactured by chemical methods Over-free polyimide substrates have been used in circuit board manufacture for a long time. Especially when using chemical Methods occurs the disadvantage of the greater water absorption of polyimide in the foreground compared to other polymers. It has, for example showed that the adhesive strength of the entire surface on polyimide films Electroless and electrolytically deposited copper layers for polyimide  surface during thermal treatment, for example during soldering Lich reduced or completely canceled. To the appearance of bla to avoid sen-shaped withdrawals during thermal treatment, It is generally proposed to use the coated polyimide films after Annealing deposition.

However, the annealing treatment is not enough to prevent blisters, if polyimide is provided on both sides and all over with copper layers foils are exposed to excessive thermal treatment. In In this case, the trapped moisture from the chemical The metallization process no longer occurs during the annealing give way, so that they explode during thermal treatment emerges from the polyimide foil and the copper coating from the polyi mid surface stands out.

For the reasons mentioned above, other methods have become adherent Metallization of polyimide substrates developed. Because of the requirement tion, sufficient adhesive strength of the deposited metal layers also during and after thermal stress on the To achieve substrates, vacuum processes were used for metallization set. Metal deposition by decomposing volatile metal ver Glow discharge bonds are a successful alternative. In DE 35 10 982 A1, such a method for manufacturing is electrical conductive structures on non-conductors, for example polyimide films Deposition of metallic films on the non-conductive surfaces by cerium settlement of organometallic compounds in a glow discharge zone disclosed. The deposited metal films preferably serve as kata lytically active seed layers for subsequent electroless metallization of the surfaces.

DE 37 44 062 A1 describes a process for producing metallic  Structures on fluoropolymers or thermoplastics by decomposing organometallic compounds in a glow metal described.

DE 38 06 587 A1 describes a process for producing metallic Structures on polyimide through decomposition of organometallic compounds gene shown in more detail in a glow discharge.

Other processes and organometallic compounds are described in the Publications DE 37 16 235 A1 and DE 38 28 211 C2 are disclosed.

With these methods it is possible to apply adhesive metal layers to poly to produce imide surfaces when on the first by means of Glimmentla metal layer produced further metal layers from currentless and electrolytic metallization baths are deposited. In the ge State-of-the-art documents are used for the de-energized Metallization usual copper or nickel baths specified.

In order to achieve the purest possible metal layers with the glow discharge method to manufacture, d. H. Metal layers without significant carbon and Oxygen admixtures, the substrate must during the metal separation be heated to the highest possible temperature. The coal Additives containing substances come from the organic components the most volatile organometallic used in the deposition Connections. The influence of the substrate temperature on the coals substance content of the metal deposited with the glow discharge method Layers are described, for example, in E. Feurer and H. Suhr, "Thin palladium films prepared by metal-organic plasma-enhanced chemical vapor depo sition ", Thin Solid Films, 157 (1988), 81, 84 the carbon content of the layers with increasing substrate temperature from. From this publication it can also be seen that the palladium layer  ten at room temperature contain almost 30 wt .-% carbon. First when heating the substrate to temperatures above 100 ° C Carbon content can be reduced to negligible levels.

If the metal layer contains too much carbon due to sufficient decomposition of the metal compounds in the glow discharge or due to insufficient desorption of the only partially decomposed ligan connections from the substrate surfaces, so is the conductivity of the deposited metal layers only slight, and also their catalytic activity to start electroless metal deposition on the Surfaces also not sufficient.

For many applications, heating the substrates is not the case wishes, since these are not sufficiently stable thermally. Therefore Attempts have been made to determine the carbon content of the metal layers other way to lower. For example, in the aforementioned print written by E. Feurer and H. Suhr proposed the separated Me post-treat layers with an oxygen plasma. Another According to experiments by these authors, the alternative is to use the Me tallabscheid argon commonly used as a carrier gas To replace oxygen. This will replace palladium with palladium oxide deposited by a subsequent treatment in one Hydrogen plasma in turn reduced to a metallic palladium film can be decorated. However, this procedure is very complicated and complex. In addition, the organometallic compounds decompose already when the oxygen is passed through the storage vessel, the contains these compounds, so that only a small part of the Glimmentla zone reached.

The present invention is therefore based on the problem that  Avoid disadvantages of the prior art and a godfather application P 44 38 791.1 to find a supplementary procedure with which it succeeds in adhering to low-carbon and low-oxygen metal layers Surfaces, electrically non-conductive substrates at low temperatures separating doors without further treatment of the deposited NEN metal layers is required. It is also intended to be a simple process with which it is possible to produce metallized substrates len, which is also used for the production of electrical circuit carriers can be.

The problem is solved by claims 1, 2 and 10. Preferred Embodiments of the invention are specified in the subclaims ben.

Low-carbon and low-oxygen metal layers can with a Ver drive are obtained, in which the volatile metal compounds in Presence of oxygen on the substrate surfaces in a glow discharge can be decomposed. The oxidizing gas mixture also contains the volatile metal compounds and oxygen inert gases chooses from the group consisting of nitrogen and noble gases. As a noble gas is preferred for reasons of cost argon.

Due to the oxidizing ability of the oxygen in the gas mixture the substrate surfaces after a possible cleaning and radio tionalization of the surfaces also during the metal deposition white ter cleaned, here preferably from the glow discharge standing organic fragments of organometallic compounds gen. By using a gas mixture that in addition to oxygen Contains inert carrier gases, the formation of metal oxide can also layers are largely prevented, their electrical conductivity  and catalytic activity for electroless metal deposition would be high enough. It also prevents the metallorga African compounds before the glow discharge is initiated decompose zone as the carrier gas for the compounds is not pure acid material but a gas mixture with the inert gases is used through which mostly liquid metal compounds are passed.

To a large extent in a particularly suitable gas mixture for formation carbon and oxygen free metal layers the ratio of Partial pressure of oxygen to that of the inert gases in the gas medium to a value between 2: 1 and 1: 8, preferably between 1: 3 and 1: 4. Assuming that oxygen Ligands in the organometallic compounds to carbon dioxide and Water will be oxidized when a partial pressure ratio is set from 1: 3 to 1: 4 below the theoretical (stoichiometric) Consumption of oxygen lying value determined. For example, who that when setting the ratio of 1: 3 in the evaporation of about 300 mg of π-allyl-π-cyclopentadienyl-palladium- (II) at 45 ° C an average of about 150 standard cm³ of oxygen is used. For the full however, constant oxidation of the ligands in the compound would result in 330 Standard cm³ are required. Experiments have shown that usually between 20 and 70% of the stoichiometric oxygen amount needed.

The total pressure of the gas mixture in the reaction vessel in which the Decomposition of the metal compounds takes place, is preferably between between 1 Pa and 50 Pa.

As volatile metal compounds are palladium, copper, gold or Platinum compounds or mixtures thereof are used. Other metal Connections can also be used in principle, provided that the one created  Metal layer catalytic for the subsequent electroless metallization is. Become metal during metal deposition using glow discharge layers with sufficiently high electrical conductivity for direct subsequent electrolytic metallization, so can also use other metal compounds to form the first metal layer Det are, for example molybdenum compounds.

Palladium has been found to be particularly advantageous because it is Etch easily removed and another metal layer on top of it can be deposited without current from a copper bath. Will be on other metals as palladium to deposit the first metal layer turns, the substrate is turned into an electroless metallization Activation solution, for example a palladium chloride solution, immersed.

By creating a thin layer of palladium for the subsequent electroless metal deposition of catalytically active metal layers, so that further activation of these metal layers, at for example with solutions containing precious metals, is not required. With The process according to the invention uses carbon and oxygen poor metal layers formed by means of glow discharge, so that they do not need further treatment, for example in a glow charge in the presence of reducing gases such as hydrogen.

As volatile metal compounds come according to the state of the art known compounds, for example dimethyl-π-cyclopentadienyl Platinum, dimethyl gold acetylacetonate and in particular π-allyl-π-cyclopen tadienyl-palladium (II). The in the previous publication The specified deposition conditions are based on the generation of the Metal layers according to the inventive method accordingly transferable.  

Before the metal deposition by means of glow discharge, the substrate surfaces in a glow discharge process with an oxidizing Gas mixture containing oxygen and inert gases, pretreated. This The gas mixture naturally does not contain any volatile metal compounds gene, since no metal layers were deposited in this process step should be.

Then a first metal layer according to the aforementioned Ver drive down on the substrate surfaces. After that, too a reinforcement of the metal layer thickness on a second metal layer the surfaces are deposited with an electroless plating bath will. For this purpose, an electroless plating bath is preferably used Nickel, copper, cobalt or palladium bath or a bath for deposition of alloys of these metals.

Electroless deposition is used to create adhesive metal layers a nickel / boron alloy is particularly well suited because it supply of metal structures of an electrical circuit carrier from a all-over metal layer can be easily etched out.

The method can also be advantageous for the deposition of the metal layer ten on polyimide surfaces because the substrate material is treated gently.

When coating polyimide films, the second metal layer is in a preferred process variant from a neutral or acidic provided electroless plating bath deposited. Part of the means Glow discharge deposited metal layer shows only a slight Adhesion to the substrate surface. This part is followed by the subsequently electrolessly deposited metal layer from a neutral or acidic metallization bath solidified, so that the overall composite  has good adhesive strength. The adhesive strength of such metal layers is not reduced even by contact with aqueous alkaline solutions device.

In addition, polyimide decreases when using neutral or acidic Electroless metallization baths have significantly less moisture than in Use of alkaline electroless plating baths, so that after the Treatment also leaves less hydroxyl ions in the material hydrolytically (dis can have a sociating effect and weaken the bond. It was found that the best results with electroless metallization baths with a pH between 2 and 7 can be achieved.

The following are exemplary embodiments of the invention described:

Various materials can be considered as substrates: firstly Polyimide, but also epoxy resins and their composites with glass or carbon fibers, paper layers or other fillers, Polyetherimide, ceramics and other substrate materials. Polyimide is used in various forms of trade and semi-finished products: Ne ben polyimide films as such can also be pressed with others Backing materials, such as FR4 material (epoxy resin / glass fiber) and copper foils can be used in a layered laminate. Furthermore, plate-shaped polyimide substrates as well as spin coating layers are coated by the process according to the invention. Under Polyi mid is also to be understood as material that consists of dissolved and / or post-cured polyimide is produced. In addition, you can Polyimides with different chemical structures can be used. The material called KAPTON H, trademark of DuPont de Ne  mours, Inc., Wilmington, Del., USA, is a condensation polymer tion product of pyromellitic dianhydride (PMDA) with diamino diphenyl ether (DDE). The material called UPILEX, trademark of the company UBE Industries, Tokyo, Japan, on the other hand, is from a condensation pro derives from 3,4,3 ′, 4′-biphenyl-tetracarboxylic acid dianydride (BPDA) with DDE (UPlLEX-R) or with p-phenylenediamine (PPD) (UPlLEX-S).

To manufacture electrical circuit carriers are before the Abschei formation of the first metal layer by means of glow discharge, if necessary Holes punched, drilled or etched into the substrate. After that it will perforated substrate cleaned, for example with a wetting agent tend aqueous solution.

The surfaces to be coated can then be coated with glow pre-treated discharge. For example, the surfaces etched, cleaned and / or functionalized with reactive groups by the gases react with the chemical groups on the polyimide surface Ren. For the pretreatment, the substrate is in a normal plasma reactor, for example introduced into a parallel plate reactor, which as Tube or tunnel reactor is formed. The glow discharge of about 1000 watts for pretreatment can be used with both direct current and Alternating current (high frequency in the kHz or MHz range) are generated.

The surfaces are preferably in oxygen or in an acid Etched substance / argon or oxygen / nitrogen mixture. For example becomes an oxygen / argon mixture with a partial pressure ratio of 1: 1 used at a total pressure in the reactor of about 8 Pa. The In this case the exposure time is typically 30 minutes. In a Another variant is pure oxygen with a pressure of 0.25 hPa used. With a glow discharge power, the substrate becomes inside cleaned by 90 seconds.  

The first metal layer that is also catalytically active and adherent has a telend effect on the surfaces pretreated in this way by decomposition zen volatile metal compounds applied. For this, an inert Carrier gas through a reservoir that is the mostly liquid metal organ contains African connection, passed through. The inert gas can additionally Lich contain oxygen. Will pass through to the carrier gas the liquid metal compound in the storage container is not supplied with oxygen mixes, this is introduced separately into the plasma reactor and ge reaches the glow discharge zone in this way. When decomposing the Metal compounds are formed depending on the coating conditions gene, a thin high-purity metal layer with a layer thickness of 0.01 µm to 0.1 µm.

Normal parallel plate reactors are used for the metallization, which are designed as tunnel or tube reactors. With the metallization the pressure in the treatment chamber is generally 1 Pa to 50 Pa. Usually a temperature close to room temperature becomes wide below 100 ° C in the laminate by varying the electrical power of the Glow discharge set. For thermal protection of the substrate additional heating of the substrate is avoided. This is too not mandatory.

On this base metal layer, the second metal layer, for example a palladium, a nickel / boron alloy or a nickel / phosphorus Alloy layer, by electroless metallization from an acid or neutral bath can be applied. However, the metals also come Gold and cobalt or their alloys as well as pure nickel or others Cobalt alloys. It becomes a fully additive metal structure preferably electrolessly deposited palladium.

If palladium is used to generate the conductor tracks according to a different procedure  as the additive technique, such as the semi-additive Process, applied as a second metal layer, must be taken into account be that this palladium layer abge only in a small layer thickness will be divorced. This is necessary because palladium is difficult to etch and therefore can only be easily removed from the surfaces, when the etchant penetrates the layer through pores and the palla layer can lift off from below.

The following are preferred as electroless plating baths Bathroom solutions used:

• - Electroless nickel bath with hypophosphite as a reducing agent Production of nickel / phosphor layers (instead of nickel sal Cobalt salts can also be used to separate cobalt / phos layers or a mixture of nickel and cobalt salts Deposition of nickel / cobalt / phosphor layers used will);
• - Electroless nickel baths with dimethylaminoborane as a reduction agent for the production of nickel / boron layers (as reducing agent tel is also diethylaminoborane instead of dimethylaminoborane suitable);
• - Electroless palladium baths with formic acid or its derivatives as a reducing agent;
• - Electroless copper bath with hypophosphite as a reducing agent.

In addition to the baths mentioned, other bath types or baths can also be used can be used to deposit other metals. These baths should be acidic or neutral, d. H. preferably a pH between 2 and 6 max. 7 have.

Further metal layers made of electroless can be placed on the second metal layer  or electrolytic metallization baths. If the second metal layer already has a sufficient layer thickness has so that it is pore-free, the deposited on it Metal layers are also created with alkaline metallization baths the. In principle, all separable metals can be used for this. It the usual electroless and electrolytic baths are used.

The substrates are treated with the aqueous treatment baths, for example wise in electroless or electrolytic metallization, through thawing chen in the treatment solutions, but also in so-called horizontal Treatment plants in which the treatment solutions by gushing brought into contact with the substrates.

The carbon and oxygen content of the metal layers deposited by means of glow discharge can be determined, for example, by means of ESCA (Electron Spectroscopy for Chemical Application). For this purpose, the coated substrate is placed in an ultra-high vacuum chamber and exposed to X-rays (Al-K _α or Mg-K _α ). The uppermost atomic layers of the metal layer are excited and ionized by the high-energy radiation, so that electrons emerge from the material. Their energy is measured so that an element-specific quantitative analysis of the composition of the metal layer is possible.

The following examples serve to explain the invention. The following conditions were met in all examples:
Reactor type: parallel plate reactor, high-frequency voltage at the substrate electrode,

Frequency: 13, 56 MHz,
Substrate temperature: 35-45 ° C.

Example 1 (deposition of palladium on KAPTON H film)

1. Pretreatment:
Gas: oxygen,
Pressure: 0.25 hPa,
Gas flow: 100 standard cm³ / min,
High frequency power: 1000 watts,
Power density: 0.8 W / cm²,
Treatment time: 90 seconds;

2. Palladium deposition using glow discharge:
Organometallic compound: π-allyl-π-cyclopentadienyl-palladium- (II),
Gas: Ar / O₂ in a 3: 1 mixture (volume ratio),
Pressure: 0.1 hPa,
Gas flow: 25 standard cc / min,
High-frequency power 600 watts,
Power density: 0.5 W / cm²,
Evaporator temperature: 45 ° C.

300 mg (Δ 1.4 mmol) of the organometallic compound were ver evaporates and transferred to the reactor. A total of 60 Standard cc of oxygen consumed in the argon / oxygen mixture. In In another experiment, 230 standard cm³ of oxygen were used needs. In both cases, largely carbon-free palladium get layers. Assuming that the Ligan that of the organometallic compound to carbon dioxide and water oxi 330 standard cc of oxygen would be dated in the present case to be required.  

Example 2 (deposition of palladium on KAPTON H film with subsequent gender electroless and electrolytic metallization)

1. Pretreatment:
Gas: oxygen,
Pressure: 0.25 hPa,
Gas flow: 100 standard cm³ / min,
High frequency power: 1000 watts,
Power density: 0.8 W / cm²,
Treatment time: 90 seconds;

2. Palladium deposition using glow discharge:
Organometallic compound: π-allyl-π-cyclopentadienyl-palladium- (II),
Gas: Ar / O₂ or N₂ / 0₂, each in a 3: 1 mixture (volume ratio),
Pressure: 0.1 hPa,
Gas flow: 25 standard cc / min,
High-frequency power 600 watts,
Power density: 0.5 W / cm²
Evaporator temperature: 45 ° C,
Treatment time: 10-15 minutes,

3. Deposit the nickel / boron layer from a weakly acidic nickel / boron bath with dimethylaminoborane as the reducing agent:
Composition, for example:
Nickel sulfate (NiSO₄.5 H₂O) 40 g / l,
Dimethylaminoborane 4 g / l,
Sodium citrate 20 g / l,
Lactic acid (85% by weight) 10 g / l
in an aqueous solution pH 7.0
Temperature: 40 ° C,
Treatment time: 2 minutes.

4. Electrolytically deposit copper from a sulfuric acid copper bath (CUPRACID BL from Atotech Deutschland GmbH, Berlin, DE):
Current density: 2 A / dm²,
Layer thickness: 25 µm.

5. Coating the metal layers with a dry film resist (for example Riston type from DuPont de Nemours, Inc.):
Expose,
Develop in 1 wt .-% Na₂CO₃ solution.

6. Etching the copper and the nickel / boron layer:
Etching solution: CuCl₂ / HCl,
(Total copper content: 1 20 g / l,
1.5% by weight HCl, 40 ° C, NaCl saturated).

7. Etching off the palladium layer:
Etching solution: HNO₃ conc. / HCl conc. 1: 3, 1: 1 diluted with water, room temperature,
Treatment time: 15 seconds.

8. Remove the dry film resist in acetone.

Example 3 (deposition of palladium on UPILEX S film followed by electroless and electrolytic metallization)

1. Pretreatment:
Gas: oxygen,
Pressure: 0.25 hPa,
Gas flow: 100 standard cm³ / min,
High frequency power: 1000 watts,
Power density: 0.8 W / cm²
Treatment time: 90 seconds;

2. Palladium deposition using glow discharge:
Organometallic compound: π-allyl-π-cyclopentadienyl-palladium- (II),
Gas: Ar / O₂ or N₂ / O₂, each in a 4: 1 mixture (volume ratio),
Pressure: 0.1 hPa,
Gas flow: 25 standard cc / min,
High-frequency power 600 watts,
Power density: 0.5 W / cm²
Evaporator temperature: 45 ° C,
Treatment time: 10-15 minutes,

3. Deposit the nickel / boron layer from a weakly acidic nickel / boron bath with dimethylaminoborane as the reducing agent:
Composition, for example:
Nickel sulfate (NiSO₄.5H₂O) 50 g / l,
Dimethylaminoborane 2.5 g / l,
Sodium citrate 25 g / I,
Lactic acid (85% by weight) 25 g / l,
Thiodiglycolic acid 1.5 mg / l,
in an aqueous solution pH 6 to 7,
Temperature: 40 ° C,
Treatment time: 2 minutes.

4. Electrolytically deposit copper from a sulfuric acid copper bath (CUPRACID BL from Atotech Deutschland GmbH):
Current density: 2 A / dm²,
Layer thickness: 25 µm.

5. Coating the metal layers with a dry film resist (for example Riston type from DuPont de Nemours, Inc.)
Expose,
Develop in 1 wt .-% Na₂CO₃ solution.

6. Etching the copper and the nickel / boron layer:
Etching solution: CuCl₂ / HCl,
(Total copper content: 120 g / l, 1.5% by weight HCl, 40 ° C, NaCl saturated).

7. Etching off the palladium layer:
Etching solution: HNO₃ conc. / HCl conc. 1: 3, 1: 1 diluted with water, room temperature,
Treatment time: 15 seconds.

8. Remove the dry film resist in acetone.

After performing the procedures of Examples 2 and 3, adherent Get metal layers that both thermal treatments, such as for example a soldering process, or the treatment in aqueous al withstand potassium solutions without reducing the adhesive strength.

The adhesive strength of the metal layers on the substrate surface is in particular by heat treatment after the deposition of the Electrolessly and electrolytically deposited metal layers increased (at for example, one-hour annealing at 120 ° C).  

Instead of argon, another noble gas, For example, neon can be used, the same experimental results nisse are preserved.

Instead of the oxidizing gas mixture in the examples in the Process steps 2. only inert gas mixtures without oxygen used, for example pure nitrogen or pure argon hen carbon-containing palladium layers during the deposition by means Glow discharge. The in the electroless and electrolytic Metallab Metal layers obtained by separation also have a high level of adhesion strength to the substrate surface. However, this drops to very small Values if the polyimide film provided with copper structures is in process Step 5 is immersed in an alkaline developer solution.

Claims (10)

1. Process for depositing low-carbon and low-oxygen metal layers on surfaces of electrically non-conductive substrates at temperatures close to room temperature by decomposing volatile metal compounds on the substrate surfaces by means of a glow discharge process in the presence of inert gases, according to patent 4438 791 (patent application P 4438791.1), characterized in that that the volatile metal compounds are decomposed in the additional presence of oxygen. 2. Process for the metallization of electrically non-conductive surfaces of the substrates at temperatures close to room temperature with the essential process steps:

• - pretreating the surfaces by means of a glow discharge process with an oxidizing gas mixture containing oxygen and inert gases,
• Depositing a first metal layer on the surfaces by decomposing volatile metal compounds on the substrate surfaces by means of a glow discharge process in the presence of inert gases and oxygen,
• - Deposition of a second metal layer on the surfaces with an electroless metallization bath.

3. The method according to any one of the preceding claims, characterized characterized in that the inert gases are nitrogen and noble gases be applied. 4. The method according to any one of the preceding claims, characterized ge indicates that the ratio of the partial pressure of oxygen to which the inert gases in the gas mixture to a value between 2: 1 and 1: 8, preferably between 1: 3 and 1: 4 is posed. 5. The method according to any one of the preceding claims, characterized ge indicates that the partial pressure of the gas mixture during the decomposition volatile metal compounds to a value between 1 Pa and 50 Pa is set. 6. The method according to any one of the preceding claims, characterized ge indicates that as volatile metal compounds Palladiumver bindings are used. 7. The method according to any one of the preceding claims, characterized ge characterizes that as an electrically non-conductive substrate polyimide is used. 8. The method according to any one of the preceding claims, characterized ge  indicates that a nickel, Copper, cobalt, palladium or alloy bath of these metals ver is applied. 9. The method according to any one of the preceding claims, characterized ge indicates that a nickel / boron alloy is used as the second metal layer is deposited without current. 10. Use of a method according to one of claims 1 up to 9 metallized substrates for the production of electrical scarf executives.