DE4203577A1 - SELECTIVE METHOD FOR THE PREPARATION OF PRINTPLATTEN - Google Patents

Description

Process for the production of metal layers on non lei substrates such as plastics and kera mik, are known since the 60s and exist in the Application of a palladium catalyst to the substrate with subsequent electroless metallization.

The types of application are naturally very different Lich. These include the metallization of plastic counter stances, such as motor vehicle accessories, furniture pieces, housewares, etc., or the production of Printed circuit boards and electromagnetic shielding.

These methods usually consist of deposition a thin layer of copper or electroless nickel a previously catalyzed substrate with subsequent amplification kung of the metallized layer via an electrolytic Plating. The deposition of the electroless plating is commonly referred to as additive process, while the subsequent electrolytic plating as a semi-additive Method is known.  

There are many variants today, especially for the production of printed circuit boards by Subtraktiv-Ver proceed to completely additive procedures. at a subtractive process is a metal coating or a Metal layer usually by etching the metal layer removed from a non-metallic layer.

Various printed circuit boards can be used to produce multilayer plates are laminated together. In such more layered boards is the circuit of a plate with the scarf tion of one or more of the other plates of the More interconnected layer system. This is achieved by contacting a point or points on the track or the lei strip the plate cushion or circular areas Metal shapes. These pillows can also be opposite the ladder be isolated. The other plate or the others Plates that are to be connected to it are in ent speaking manner provided with metallic areas, and When laminating, the areas of the different Plates aligned one above the other.

The multilayer board is then pressed and cured, according to which the metallic areas of the multilayer panels are made be drilled to form through holes. The through diameter of a hole is much lower than the through diameter of the metallic area, the ratio of the Diameter between the metallic area and the Bore is about 2: 1 or more, so that the total at least a portion of a plate comprising with the help of a through hole, which passes through the Be rich stretches across one area from another Plate is aligned. Since the through hole in the section in Ideally, an area of alternating layers of Be rich of the individual printed circuit boards, which are not the lei  tende base are separated, must represent one electrically conductive element used in the through hole be an electrical connection between the metal produce chemical areas. This is about a procedure achieved, known as through hole plating (PTH) is.

Such methods also find the connection of two conductive metal surfaces use a single not one have conductive or dielectric plate which between the conductive surfaces is arranged to a printed circuit board manufacture. Plates of such type and the manufacturer Through holes in such plates lie in the Within the scope of the present invention and are of the here used term printed boards, which covers the whole Description is used with covered.

Before the through-hole plating is performed can, soils in the hole must be removed.

After removing soiling, the passageway becomes hole plated. Electroless copper is called PTH plating used material. For this purpose, known power used loose standard copper plating solutions. To the electroless deposition of copper on a non-conductive To promote surface, the non-conductive surface is covered with a Treated tin (II) chloride activator solution, after which a Superactivator solution of divalent palladium chloride follows. The stannous chloride becomes stannic chloride oxidized and the palladium chloride to zerovalent palladium reduced.

A preferred method is to use an activator using colloidal palladium comprising tin (II)  contains. Tin (II) forms a protective colloid around the metal palladium, and the solution implants a site zerovalent palladium on the nonconductive surface for Initiate the deposition of copper by chemical Reduction. A post-activator, usually an acid, becomes then used to solubilize the protective colloid and to release the palladium.

The subsequently applied electroless Kupferabscheidungslö solution contains metal ions, d. H. Copper (II) ions, and a Reducing agents, such as formaldehyde, the Copper (II) ions in the solution to metallic copper redu when it reacts in the presence of the palladium catalyst Ver finds application. The copper metal will be on the surface of the Through hole plated and provides an electrical con clock with the walls of the metallic cushions in through outgoing hole.

The plate is then transferred to the electrolytic process leads, in which the copper deposit amplified and a Etching resist (tin, tin-lead, gold, organic polymers u. a.) Is applied. mask removal (Demetallization), Etching, Sn / Pb reflux (if present) and final operations are the next steps.

After etching, additional process steps can be carried out be led, the removal of tin / lead, the choice wise application of a solder mask and the optional Aufbrin Soldering via "hot air leveling" or other include similar process steps.

With respect to the metallization and image transfer process are various embodiments with more or less success been tested. These include:

• a) The use of a catalyst based on colloidal copper instead of palladium (LEA RONAL),
• b) the use of an ionic palladium catalyst without tin (SHEARING),
• c) the use of an electroless copper solution containing the "Accelerator" after catalysis with the classical Mixed catalysts releases (SHIPLEY),
• d) perforated metal carried out in the electrolytic copper bath tion via a modified preparation treatment treatment / catalysis to eliminate electroless copper (EE-1 method of PCK, Morrissey et al., U.S. Patent No. 4,683,036 and GB-PS 21 23 036),
• e) hole metallization over colloidal carbon (OLIN HUNT'S BLACK HOLE PROCESS).

Most of these modifications and new procedures (the EE1 procedure is the exception) but include in Basically the traditional approach, with the consequences to apply the basic steps:

• 1) Chemical metallization
• 2) image transmission
• 3) Electrolytic metallization.

Efforts have been made for ways for many years show, according to which the holes after the image transfer can be metallized, d. H. through the scheme of a

• 1) image transmission
• 2) metallization.

The difficulties of such a process are twofold Nature:

• a) The current trend for an almost exclusive use masks (plating resists), which are in one  aqueous solution developable and in an alkaline aqueous environment are removable, requires that all Liche baths in the metallization sequence are acidic (and not only in electrolytic metallization tion). This separates the classic degreasing medium / treatment agent as well as with formaldehyde redu graced electroless copper baths.
• b) The catalysts to be used must be se be more than that they sen the surface of the holes without having to sensitize the surface of the mask awareness.

However, none of the methods described so far allows such a selective approach.

LEA RONAL, in collaboration with E.I. YOU PONT DE NEMOURS and CO.INC. developed a selective process that halfway aqueous dry films which are soluble in solvents and in an alkaline aqueous environment are removable, be is restricted, being electroless copper-plated. This Ver However, driving is relatively complex and its use is great Subject to restrictions. It was therefore not used.

In 1989, SCHLOTTER introduced a selective process called SLOTOPOSIT characterized by the following steps: a preconditioning step (before image transfer) using a SO ₃ -containing gas phase, a reduction step after catalysis, and an electroless plating step Nickel at a pH of about 5.5 at a temperature of 40 ° C. This process is compatible with all types of dry films, including those processed in an aqueous environment.

The invention is based on the object, the ge above called and other difficulties of the prior art to avoid and a method and compositions for To create metallization of a nonconductive substrate, where fewer process steps than in the process of the prior art find use.

According to the invention, a method and together for the application of metallic coatings to a non-conductive substrate through the basic steps of the image Transmission with subsequent metallization available be put.

Furthermore, a method and compositions for Coating a non-metallic substrate over a Selective process are created in which a Coating mask and a catalyst find use, the non-conductive substrate for subsequent Aufbrin sensation of metal coating compositions without sensitizing the surface of the mask.

According to the invention, a method and together for applying a metal coating to a non-conductive substrate by a selective process not on semi-aqueous dry film ver driving is limited.

Finally, a method and compositions for selectively coating a non-metallic substrate with metal coatings should be provided without the use of highly corrosive compounds, ie SO ₃ .

The above object is achieved by a method so as a solution with the features of the claims ge solves.

Further developments of the invention will become apparent from the dependent claims out.

The invention is described below with reference to Ausführungsbei explain in detail.

The present invention relates to novel methods and Compositions for pretreatment of substrates The use of catalysts and compositions for Stromlo However, metallization is primarily novel Catalyst compositions for applying a metal Composition directed to a non-conductive substrate.

The invention relates both to a method and to a composition for metallizing a not me metallic substrate with a metal coating by Kombina tion of a catalyst with the substrate, wherein the cataly on the oxides of a Group VIII noble metal Periodic table of elements based. The substrate will open catalyzes this way, and an electroless or electro Lytic metal composition is then applied to the catalyzed substrate applied to a substrate on the substrate Form metal coating. It was inventively Festge represents that after the catalytic treatment with the oxide precious metal of group VIII the following Coating with the metal composition easier and faster when the oxide becomes zero Group VIII noble metal is reduced. This Re production can be carried out in various ways. Where the electroless coating also contains a reducing agent,  the noble metal of group VIII is in particular to egg The zero-valent metal reduces when the reducing agents Hypophosphites, borohydrides, hydrazines or aminoboranes. If the Me used to form the metal coating A composition containing an aldehyde will have a certain Reduction of the oxide of Group VIII noble metal enough; however, the more effective reducing agents are above-mentioned aldehyde-free materials. additionally finds some reduction of the oxide of the precious metal Group VIII takes place when an electrolytic metal together Applied to the catalyzed substrate and the Metal is deposited electrolytically.

The reduction can also be carried out as a separate step be, d. H. after the deposition of the oxide of the precious metal Group VIII can be a chemical reducing agent on the catalytically treated substrate are applied, namely especially such an agent, acting on the hypophosphites, Borohydrides, hydrazines or amine boranes and in some cases len aldehydes or the various equivalent means thereof based. It is also possible that the catalytically treated Electrolytically reduce substrate by placing it in a electrolytic bath emerges as the cathode and in known Way to let an electric current flow through the bath.

One of the essential features of the invention is in the Discovery that the oxides of Group VIII noble metals either not adhere to the coating mask or to egg nem much larger measure selectively on the non metal metallic substrate, for example a plastic substrate (Printed circuit boards), a ceramic or anodized aluminum top surfaces are applied as to any coating mask, also on such a substrate may be present, so that an optional application of a  electroless or electrolytic metal coating on the consisting of the substrate and the coating mask Ein means that the non-metallic substrate in the we is substantially coated while the coating mask essentially not be with the metal composition is layered.

It was found that by carrying out the inventions to the invention process and use of the invention Compositions printed circuit boards, in particular those print plates, which optionally contain through holes, in one essentially two-stage process with image transmission and subsequent metallization can be plated.

Precious metals of group VIII, prepared according to the present Invention can include Ru, Rh, Pd, Os, Ir and Pt, the preferred metals being Rh, Pd, Ir and Pt and in particular Pd.

The novel catalysts of the present invention um consider a colloidal oxide of a noble metal of the group VIII, as described herein, in combination with a lower molecular weight organic acid, one Salt of a group IA or IIA metal of the period systems of elements that interact with an organic acid lower molecular weight or a halo acid ba Siert, and optionally a nonionic or anionic Surfactant, nicotinic acid or hydrogen peroxide.

The invention further relates to a pre-rinse composition, before the application of the above-mentioned cata- is applied to a non-metallic substrate and on a lower molecular weight organic acid a metal salt of group IA or IIA of an orga  lower molecular weight or lower acidic acid Halogenic acid and optionally a nonionic or anionic surfactant, nicotinic acid, coumarin, adenine, guanidine or hydrogen peroxide based.

According to the invention also a novel electroless over Zugszusammensetzung found that a nickel salt in Kombina tion with a group IA or IIA metal of the period system of elements and an organic acid with low gerem molecular weight. The coating composition also contains an amine borane and a lead II or lead IV-salt stabilizer.

The invention also relates to a novel solution for cleaning of a non-metallic substrate, the alkali metal or alkaline earth metal phosphates and an alkali metal salt of EDTA in combination with various surfactants and a fluoride contains salt.

The various non-metallic substrates erfindungsge can be provided with a coating include plastic substrates, ceramic substrates and anodized aluminum. egg nige of the plastic materials according to the invention be can be coated, in particular include printed circuit boards, and especially those printed circuit boards, the one not lei tende or dielectric base, from a Fa material such as glass fibers, paper and the like, was prepared and with a resin material, for example an epoxy resin or a phenolic resin is. These printed circuit boards are generally known as rigid Plates, although according to the invention also flexible plates be can be coated, and include thermoplastic dielectric layers, such as fluorocarbons fabric polymers, nylon polymers, polyimides, with kevlar  (Trademark) reinforced polymers, polyparabanic acids and polyester. In addition to the coating of non-metal metallic substrates based on the aforementioned Mate based on whether or not they are dielectric Plates or not, can also other polymers be coated, for example, polyolefins, as in For example, polyethylene, polypropylene and copolymers there of, ABS polymers (acrylonitrile-butadiene-styrene-Polymeri sate) and the like.

The metals that are coated with electroless processes may include all metals that are electroplated can be, in particular nickel, copper, cobalt, gold or silver and their various alloys. When the stream loose bath containing a hypophosphite reducing agent also obtained alloys of the metal and phosphorus, so that these types of alloys also in the context of the inventions lie. In addition to the unpowered Edelme Gold and silver can also be used for other applications Precious metals are deposited, such as Palla dium, platinum and the like.

Furthermore, nickel-molybdenum-boron and nickel-tungsten-boron can be removed divorced, in some cases as partial or complete replacement for gold in electronic application serve cases. Cobalt-phosphorus and nickel-cobalt-phosphorus Alloys can also be used as metal coatings the. These alloys have good magnetic properties and are suitable for use cases which are such need to work.

As explained above, the catalyst is the present invention also for the application of electro lytic coatings directly on the non-metallic coatings  Substrate treated with this catalyst regardless of whether the catalyst with a chemical reducing agent, such as an amine borane, reduced or not reduced. The direct electrolytic plating of the catalyst with the above underlying invention treated non-metallic Subtrates is performed in a manner consistent with the EE-1 Ver drive of PCK and corresponding state of the art Technology is similar. Any metal that is electrolytic can be deposited in any way be. Such metals are known.

One of the advantages of the present invention is that these are both a method and a composition for the application of a catalyst to a printed circuit board, in particular a printed circuit board, the optional passage has holes provided, wherein the invention can be applied to every printed circuit board, whether they are have such through holes or not.

Other additives may be used to coat and verifying the catalytic properties of the composition including nicotinic acid, coumarin, adenine, Guanidine and other compounds containing nitrogen, that via single, double or triple bonds Carbon is bound (examples of singly bound Nitrogen: piperidine, gramine, tryptamine; for two times bound nitrogen: pyridine, papaverine, caffeine, folic acid; for triply bonded nitrogen: alkyl cyanides with the general formula RC N (i.e., acetonitrile).

The various salts of the group IA or IIA metals the basis of halogen acids which in the inventive  Composition find use include the acids of Fluorine, chlorine and bromine, but not iodine.

As previously explained, include in the inventive Verwen method and the composition of the invention verwen chemical reducing agents hypophosphites, borohydrides, Hydrazines or amine boranes.

The hypophosphites that can be used in this regard include hypophosphites of the metals of group IA or IIA, how these metals are defined here.

The borohydrides include Groups IA, IIA, IIIA and Over transition metal borohydrides, organoamine borohydrides, cyanoborhy dride, alkoxiborhydrides, but in particular borohydrides of Group IA and IIA. Examples of these borohydrides include the following connections:

LiBH₄
NaBH₄
KBH₄
Be (BH₄) ₂
Mg (BH₄) ₂
Ca (BH₄) ₂
Zn (BH₄) ₂
Al (BH₄) ₃
Zr (BH₄) ₄
Th (BH₄) ₄
U (BH₄) ₄
(CH₃) ₄NBH₄
(C₂H₅) ₄NBH₄
(C₄H₉) ₄NBH₄
(C₈H₁₇) ₃CH₃NBH₄
C₁₆H₃₃ (CH₃) ₃NBH₄
NaBH₃CN
NaBH (OCH₃) ₃

The hydrazines which can be used according to the invention own the formula:

in which mean:
R _{1 is} an alkyl, cycloalkyl, aryl, alkaryl, aralkyl, alkoxy, aryloxy or nitrogen-containing hetero-cyclic radical and
R ₂ , R ₃ and R _{4 are} hydrogen or the same as R₁, where at least one of the radicals R ₁ , R ₂ , R ₃ , R _{4 is} hydrogen, the alkyl radicals contain the alkyl portion of the alkaryl radical, the cycloalkyl radicals are aralkyl and alkoxy radicals which are from 1 to containing about 10 carbon atoms including the isomeric configurations thereof and the ring structure of the cycloalkyl, aryl, alkaryl, aralkyl, aryloxy and hetero cyclic moieties contains from 3 to about 17 carbon atoms including the fused ring structures.

The various hydrazines and hydrazine compounds, which can be used in this regard are further in the textbook Kirk-Othmer, Encyclopedia of Chemical Technology, 3rd Edition, Volume 12, pp. 734-771 which is hereby incorporated by reference.

The various amine boranes used in the invention include amine boranes with the following formula:

R ₃ -n H _n BH₃

Monoaminoboranes of the formula

R₂NBH₂

and bisaminoboranes of the formula

(R₂N) ₂BH

where R is alkyl, in particular a lower alkyl radical with up to 6 C atoms, aryl or haloaryl or alkaryl or aralkyl, wherein the alkyl group is a niedi gere alkyl group in the reproduced here Defini tion and the aryl group is in particular such having 6 C atoms. Examples of these are:

(C₂H₅) ₃N.HB₃
(CH₃) ₂NH.HB₃
tert-BuNH₂BH₃
C₆H₅ (C₂H₅) ₂N.HB₃
C₅H₅N · BH₃
(C₂H₅) ₃N · BCl₃
(P-BrC₆H₅) NH₂BCl₃
(CH₃) ₃N · BBr₃
(C₂H₅) NH₂ · BF₃
(C₂H₂) ₂NH₂ · BF₃
(C₂H₅) ₃N · BF₃
(CH₃) ₂NH.HB₂Cl
C₅H₅N · BH₂Cl
(CH₃) ₂NH.HB₂Br
(CH₂) ₂NH · BH₂I
(CH₃) ₃N · BHBr₂
(CH₃) ₃N · BHCl₂
(C₂H₅) ₂NH ·B (CH₃) ₃
(CH₃) ₂NH ·B (tert-Bu) ₃

The lower molecular weight organic acid comprises Acids with 1 to about 7 C atoms and can either alipha or cyclic (i.e., aromatic acids) and the various isomers thereof. Especially preferred Acids are those having up to about 3 carbon atoms.

The salts of the metals of group IA or IIA include preferably those based on lithium, sodium, potassium, Magnesium, calcium, strontium and barium, in particular Sodium, potassium and calcium. As explained above, k The catalysts optionally a nonionic or contain anionic surfactant.

The various anionic surfactants useful in this regard include:
Carboxylates based on straight-chain carboxylic acids having from about 9 to about 21 carbon atoms in combination with a metal ion or ammonium ion;
Polyalkoxycarboxylates prepared by the reaction of chloroacetate with an alcohol ethoxylate or an acrylic ester and an alcohol alkoxylate;
N-acyl sarcosinates;
Acylated protein hydrolysates;
Sulfonates comprising alkyl, aryl or alkaryl sulfonates;
lignosulfonates;
naphthalene;
Alpha-olefin;
petroleum;
dialkyl;
Amidosulfonates (N-acyl-N-alkyl taurates);
2-sulfoethyl ester of fatty acids (acyl isethionates);
ethoxylated and sulfated alcohols;
ethoxylated and sulfated alkylphenols (sulfated alkylphenol ethoxylates);
sulfated alkanolamides and sulfated triglycerides: sulfated natural oils and fats;
Phosphatester.

The nonionic surfactants that can be used to summarize:
Polyoxyethylene surfactants (ethoxylates);
Alkoholäthoxylate;
alkylphenol ethoxylates;
Carboxylic acid esters of polyols and the end hydroxyl groups of ethylene oxide chains;
Mono- and diglycerides of saturated fatty acids;
Polyoxyäthylenester of fatty acids and aliphatic carbonic acids;
Anhydrosorbitol esters of fatty acids;
Ethoxylated anhydrosorbitol esters of fatty acids;
Ethoxylated natural fats, oils and waxes;
Glycol esters of fatty acids;
Condensation products of fatty acids and hydroxyethylamines;
Distearoylamine condensates of fatty acids (fatty acid diethanolamides);
Monoalkanolamine condensates of fatty acids;
Polyoxyethylene fatty acid amides;
Polyalkyleneoxide block copolymers;
Poly (oxyethylene) -co-oxypropylene.

The amphoteric surfactants include, for example:
alkyltrimethylammonium;
alkylpyridinium;
Imidazoline derivatives prepared from 2-alkyl-1- (2) -hydroxyethyl-2-imidazolines and sodium chloroacetate;
alkylbetaines;
Amidopropylbetaines.

The above enumerated surfactants, which are among the above as The given definitions fall in detail in the Textbook Kirk-Othmer, Encyclopedia of Chemical Technology, 3rd Edition, Volume 22, pages 332-432, to the is hereby incorporated by reference.

The process according to the invention further overcomes, in particular, the main drawback of the SLOTOPOSIT process, which consists in the pretreatment carried out in the presence of an extremely aggressive gas (SO ₃ ), which is essentially a discontinuous process, only difficult to operate as a continuous Ver drive.

Unlike mixed catalysts, the tin and palladium contain the catalysts of the present Er find only palladium compounds and are free of tin.

The novel catalysts can be done in different ways be prepared, with some palladium compounds is started. Some manufacturing methods are better for Ar work in the laboratory, while others are better for Manufacturing process in the industrial frame suitable. The catalyst ren can by known methods, such as diving (i.e., dip coating), spray coating, roll coating and the like, are applied to a variety of substrates.

The following examples serve for a better explanation.

example 1

PdCl ₂ was dissolved in a NaCl-containing hot solution. After the palladium chloride had dissolved, sodium acetate was added. Thereafter, it was heated from room temperature to 90 ° C.

The concentration of the components of the catalyst may vary within wide ranges, which are given below:
PdCl ₂ of about 0.05 to about 1 g / l
NaCl from about 1 to about 100 g / l
NaCH ₃ COO from about 0.5 to about 100 g / l.

During heating, the solution took on a brown-red color on. The production time varied from one minute (at 90 ° C) up to 24 h (at room temperature). The pH was with Acetic acid adjusted to about 3.5 to about 6.0.

A good example of a catalyst composition within this catalyst family is the following:
PdCl ₂ 0.25 g / l
NaCl 10 g / l
Close to ₃ COO 15 g / l
Heat 50 ° C for 10 min
pH 4.9, adjusted with acetic acid.

When applying this catalyst composition (as well as the other catalyst compositions of the invention) Substrate may be the composition at a temperature of  about room temperature (20 ° C) to about 60 ° C, in particular about 40 ° C, wherein the substrate is about a Minute to about 20 minutes, especially about 2 minutes, with the composition can be brought into contact.

In order to prevent entrainment of previous solutions, in particular rinse water, it is advisable to contact the substrate to which the catalyst is applied with a pre-dip composition in a solution having the same composition but no palladium. For this particular catalyst, the pre-dip composition used has the following formula:
NaCl 10 g / l
Close to ₃ COO 15 g / l
pH 4.9, adjusted with acetic acid.

This pre-dip composition may be like the catalyst together Compositions by dipping, spray coating or Rollbe layers are applied to the substrate. The procedure the application of the pre-dip composition is not on the term "pre-diving" is limited.

Example 2

The catalysts of this example were also from Pal made of ladium chloride. The catalyst solution was ever but first prepared as a concentrate, with the recommended Ranges in terms of concentrations, times, tempera and the pH for the catalyst composition den in Example 1.

An example of a related catalyst composition is shown below:
PdCl ₂ 0.25 g / l
NaCl 1.5 g / l
NaCH ₃ COO 20 g / l.

The three components were dissolved in agitated water at a temperature of 55 ° C. The solution remained under these conditions for 16 h. The heating was discontinued and the pH of the solution was lowered to 4.9 with HCH ₃ COO.

After cooling to room temperature, the ge made precipitation. The solution was then carefully drained or decanted to the precipitate and part to win the solution. The winning part can be between less than about 1% up to about 100% of the initial volume vary. The use of about 1/8 of the initial volume is recommended so that the preparation of the concentrate is not very critical and a high Palladiumkonzentra remains therein. For example, if 1 ltr. Solution too was prepared, the volume of precipitation and the remaining solution 125 ml after decanting.

When the concentrate was ready, the catalyst solution was prepared by combining the following ingredients:
Concentrate (as prepared above) about 12.5 ml / l to about 500 ml / l
NaCH ₃ COO 0 to about 100 g / l
pH (adjusted with HCH ₃ COO) about 3.5 to about 6.0.

The preferred composition had the following ingredients:
Concentrate 125 m / l
Close to ₃ COO 17.5 g / l
pH (adjusted with HCH ₃ COO) 4.5.

The catalyst must be prepared under agitation. After the solution described above became homogeneous, the pH was adjusted to 4.5 with acetic acid.

As with the catalysts of Example 1, these work Good catalysts in wide temperature ranges and immersion or contact time ranges. However, it is preferred to room temperatures (about 20 ° C) and contact times of about 15 min to use.

As in Example 1, the pre-dip solution contains the same ingredients as the catalyst except for the palladium salts, and is applied to the substrate in the same manner as the catalyst in Example 1. As an example, the pre-dip solution of this embodiment may have the following composition:
NaCl 1.25 g / l
NaCH ₃ COO about 20 g / l
pH (adjusted with HCH ₃ COO) 4.5.

Example 3

The catalysts of this embodiment were prepared from palladium acetate. It is possible to make the catalysts directly without going through a concentrate as described in connection with Example 1 using PdCl ₂ . An industrial-scale production process in which the catalyst is prepared from a concentrate and maintained is of particular interest and is therefore explained below.

Preparation of the concentrate

The concentrate was prepared by adding about 0.1 to about 15 g / l and in particular 3.16 g / l palladium acetate with from about 0.5 to about 150 g / L, and more preferably about 50 g / L Sodium acetate combined.

The sodium acetate was dissolved in distilled or deionized Water was dissolved, and palladium acetate was added under agitation Solution added.

As stated in Example 1, the manufacturing changes time with the temperature, taking the time of about 30 min to varies for about 24 hours and is in particular about 5 hours, while the temperature is from about room temperature (20 ° C) to varies about 90 ° C and in particular is about 55 ° C.

After preparation, the pH was calculated from Initial value adjusted to 3.5 with acetic acid. The final The preferred preferred pH for the concentration is 5.0.

Preparation of the catalyst from the concentrate

The concentrate described above was used for the preparation a catalyst used by about 10 to about 950 ml / l of this concentrate together with 0 to about 100 g / l Sodium acetate was used and the pH to a value of from about 1.0 to about 6.5. The catalysts can be used to heat a substrate at room temperature  from about room temperature (20 ° C) to about 60 ° C clock, with the contact time as a minimum about half Minute is.

Two optimized formulations of those described above Catalysts were recovered from the catalyst concentration of the Example 3 developed. These formulations were like follows:

Formulation 1

Concentrate of Example 3 about 50 to about 150 ml / l
NaCH ₃ COO about 0 to about 20 g / l
pH (adjusted with acetic acid) about 3.5 to about 4.9 temperature about 40 ° C
Contact time about 1 to about 10 min.

Formulation 2

Concentrate of Example 3 about 50 to about 150 ml / l
pH (adjusted with acetic acid) about 1.0 to about 4.6
Temperature about 20 ° C
Contact time about 1 to about 10 min.

Formulation 2 is considered to be optimum for the manufacturing conditions considered.

The pre-dip solution for the above-described Kataly was prepared as described above, d. H. by omitting the catalyst salt from the mixture setting. Thus, the pre-dip solution for the catalysts of this example have a concentration somewhere is between about 2.5 and about 7.5 g / l. The pH was with  Acetic acid to any value between about 1.0 and about 4.6 set.

Addition of other substances to the formulations of the case games

The catalysts described in Examples 1-3 and Concentrations can be a great variety of compounds be added without their properties, behavior and Catalyst mechanism to change considerably.

Among the possible substances here are only a few specified. Many anionic and nonionic (but none cationic) surfactants, coumarin, nicotinic acid, adenine, Guanidine and compounds containing nitrogen, the via a single, double or triple bond on the coal fabric is bound.

The addition of hydrogen peroxide (H ₂ O ₂ ) is preferred in commercial processes. The substance is usually added once every two or four weeks to the catalyst and / or the pre-dip solution in an amount of about 5 ml / l, wherein the concentration of the hydrogen peroxide carries 1.5 g / l be.

Absolute purity of H ₂ O ₂ is required since hydrogen peroxide stabilized with Sn ²⁺ and Sn ^{4+ is abundant} and such ions can not be tolerated in the catalyst or concentrate mentioned.

In addition to the addition of H ₂ O ₂ or instead can be used with air agitation.

Other examples of substances that the catalyst or should not be added to the concentrate are salt acid, sulfuric acid and nitric acid (although these are in ge concentrations can be tolerated).

Alkali metal halides show a very different Behavior. So fluoride will tole in every concentration while chlorides and bromides are concentrated in low concentrations tions (<10 ion g / l) are well tolerated. Iodide always leads but to the decomposition of the catalyst.

Characterization of the new selective catalyst Definition of selectivity

The method described here and / or described here bene selective catalyst meet all of the following conditions listed below:

• 1 - they allow one or more consecutive Metal cladding on selected and given Areas of the substrate.
• 2 - The areas of the substrate resulting from this deposition are to be kept free, with a resist Mask covered with respect to the plating. in this connection it can be a liquid photoresist, a Trockenfilmfotoresist or act a screen printing ink.
• 3 - Between the catalytic treatment and Plattie tion of one or more metallic coatings If there is no interruption in the procedure or an Ent distance of the plating resist mask. The Plattie It is therefore at least from the beginning of the kataly  table treatment until the end of the desired metal plating available.
• 4 - The procedure is with all previously known plat resident families, for example liquid photos resists and screen printing inks, compatible. These include Plating resists complete in aqueous solutions are dig processable, d. H. those in aqueous Solutions are developable and demetallizable.

Proof of selectivity

All of the catalysts described above be sit selective properties. Below are two ge tested catalyst formulations with additives wiedergege ben:

example 1 Preferred concentrate | 50-150 ml sodium fluoride 0.2-1 g / l niacin 5-10 mg / l pH (adjusted with acetic acid) 4.3-4.6 temperature room temperature dive time 2-5 min

Example 2 Preferred concentrate 50-150 ml / l Octylphenol with 40 epoxy units nonionic surfactant (i.e., TRITON X-405) 0.1-0.5 ml / l pH (adjusted with acetic acid) 4.3-4.6 temperature room temperature dive time 2-5 min

You can use various substrates (i.e., epoxy resin glass fiber ser-composites, the entire field of thermoplastic and thermosetting resins and ceramics whose surfaces are in have been adequately prepared) activate, but do not activate the plat mentioned here tierungsresistflächen. Selectivity is given insofar than that a metallic deposit (electroless deposition, combined electroless and electrolytic deposition or electrolytic deposition) over previously activated Be takes place while no deposition over Be takes place rich with the plating resist were covered. As previously explained, this takes place without Removal of plating resist between catalysis and the completion of the metal deposition process.

It is by photoelectron X-ray spectroscopy (XPS) possible differences between the new mixed catalysts determine the reasons for the selectivity stand.

It was an ESCA-XPS analysis of the catalytically treated Substrates performed with the catalysts. The used substrate was FR-4 (laminate for printed circuit boards, be written in NEMA LI- / 75). The substance RISTON (trademark the company E.I. DuPont) 3615 was used as a plating resist selected. The catalytically treated samples were passed through Degreasing and treating (solution according to Example 2) of the sub strates prepared. The substrate was then poured into an aqueous Submixed solution of sodium acetate (5 g / l) dipped and with Acetic acid for about 1 minute to a pH of 4.5  provides. The substrate was then removed from the pre-dip solution removed and immersed in a catalyst solution. The cata- Tor was obtained from a concentrate containing 3.1 g / l of palla dium acetate and 50 g / l sodium acetate according to Example 3 contained. This concentrate was then distilled Water diluted to a concentration of 100 ml / l, and the pH was adjusted to 4.50 with acetic acid to give the catalyst to form a sator. The substrate then became at room temperature (20 ° C) over a period of 5 minutes in this Kataly dipped, after which the substrate from the catalyst abgezo and rinsed with distilled water for one minute has been.

The samples tested were electrical non-conductive glass / epoxy substrates with or without photo resist. In the ESCA-XBS analysis, the respective sample was irradiated with X-rays, and the energy of the freige set photoelectrons was measured. Because the electrons carry a negative charge, this charge tends to become to accumulate on the surface of the nonconductive sample, where changed by the energy of the subsequent photoelectrons becomes. The sample is electrified in this way, and it there must be a correction with respect to the measured binding energies be performed to meet this phenomenon become.

In Figs. 1 and 2, the comparison between the XPS spectra of the FR-4 substrate before and after the catalytic treatment is shown (wide scan). The detectable differences are given by the Pd-Piks and the occurrence of fluoride traces (caused by the use of Ammoni umbifluorid in the degreaser / conditioner).

A detailed analysis of the spades as a result of the third elec Tration of Pd was possible via both the FR-4 substrate and over the dry film surface between 330 and 350 eV carried out.

After making corrections due to the electrification of the sample, the following binding energies were averaged:
FR-4 substrate - 337.7 eV
Dry film - 335.8 eV

Metallic Pd is not present on any of the surfaces. The method of the Auger parameter was performed for both surfaces. It confirmed the non-metallic properties of the existing palladium. The Auger method measures the energy difference between the Pd 3d ESCA lines and the corresponding Pd-Auger PiK. These additional determinations confirmed the non-metallic state of Pd and the shift to PdO ₂ .

The binding energy over the FR-4 substrate turned up even to a value of 337.6 eV, that of PdO2 equivalent. Put on the surface of the dry film The binding energy of Pd does not affect any of the PHI manual or in the well-known manuals of Briggs and Seah (Practical Surface Analysis by Auger Electron Spectroscopy and Photoelectron Spectroscopy, Ed. Ed. D. Briggs and M.P. Seah, John Wiley & Sons, Chichester, New York, 1985).

The result obtained corresponded to an oxidation state of Pd under + 4, but did not put the value exactly of 336.1 eV for PdO.  

Taking into account the current state of knowledge, it can be stated that a mixture of PdO and PdO ₂ is most likely present over the surface of the photoresist Pd, with more PdO present than PdO ₂ .

The following results were obtained from a quantitative analysis:
Pd concentration above FR-4 6.0-8.2% (atomic percent)
Pd concentration over photoresist RISTON 3615 1.1-2.3% (atomic percent).

The same substrates treated with a conventional Pd / Sn mixed catalyst (the catalyst was a Shipley CATAPOSIT 44 catalyst, temperature 50 ° C., concentration 3%, immersion time 3 minutes) led to the following results:
Pd concentration above FR-4 about 6% (atomic percent)
Pd concentration over photoresist RISTON 3615 about 15% (atomic percent).

From the above observations, the following became Conclusions drawn:

• 1 - The on the surfaces of the substrate and on the Mask of the plating resist adsorbed palladium can not be found in the metallic state.
• 2 - There is a Pd adsorption on the surface of the plat tierungsresists available.
• 3 - Unlike a mixed catalyst (non-selective) The novel catalysts arrange five times more Pd on the substrate than on the dry film mask  (Atomic percent of about 5: 1 vs. 6: 15 with a Mishka talysator).
• 4 - There is an obvious chemical difference between the on the surface of the substrate and up the mask adsorbed species. With a mixed kata however, no differences can be detected become.

These results remained qualitatively the same as themselves the conditions changed (diving times, temperatures etc.), even as small quantitative changes occurred.

The selective nature of the novel catalysts is thus clearly proven.

Use of the novel catalyst in the chemical Production line metallization

As stated above, the PTH process is a metal procedure, which involves a series of steps which is used to coat the through holes of a print plate with a metallic deposit (normally Copper) lead. These process steps find between the Drilling and image transfer instead.

Even without using the real selective potential of this Invention can Kata reproduced in the examples be advantageously used. This novel Ka Thus, catalysts lead to extremely significant changes gen, when used in traditional and traditional sequences and methods are used.

Table 8 shows a comparison between the traditional one Method in which a mixed catalyst is used  (Method 1), the RONAMET (trademark of the company Lea- Ronal) method (method 2) and three other difference method (methods 3-5), in which the novel Catalyst family use found.

As shown in Table 8, the figures given in Ver 3-5 times used procedures 1 and 2 or are worse than these. You also own the Advantage, a smaller number of steps (12 versus 14) to need. Nevertheless, the new catalyst offers (Step 7 in Procedures 3-5) Other Benefits Made Table 8 does not show.

As further evident from Table 8, is by the fact thing that the catalysts of the present invention at a pH between 4 and 5 work compared to a pH <1 in process 1 and a pH of 3.5 in process 2, the treatment of the wastewater easier. Furthermore be the novel catalysts sit a long life, which is as large as that of a conventional Mischkatalysa tors. Equally important is the ability to work with a catalyser To be able to work, which is free of chlorides, and with a weak pH, which eliminates the possibility is that silanes are attacked. These silanes pose the binder between the resin and the glass fibers in Epoxy-bonded. The "backplating problem" (Penetration into the interior of the material), which in very dense circuits with holes of small diameter occurs, is thus eliminated.  

Table 8

Comparison between five methods of chemical metallization of printed circuit boards

Common Conditions for Procedures 3-5 in Table 8

The degreasing / conditioning operations (step 1) and the microetching step (step 4) can be carried out with any marketable products. To name just a few examples, Step 1 may be performed using Shipley's Cleaner / Conditioner 231 and Step 4 using LEA RONAL's Ronetech PS (based on persulfate) or Shipley's Pre-Etch 746 (on the base of H ₂ SO ₄ / H ₂ O ₂ ). Of course, dive times and temperatures (including rinses) must always be adhered to depending on the product type and recommended delivery.

The "Preparation for Catalytic Treatment" (Step 6) and the "catalytic treatment" (step 7) will always be with the catalysts mentioned in Example 3 or with any derivatives thereof. there has been a Dive time of 1 min in step 6 and a time for the kata lytic treatment for 4 min (i.e., using the Formulation 2 in Example 3).

Common conditions for procedures 3 and 4 in Table 8

The electroless copper deposition (step 11) can with belie marketable solutions.

High deposition rate baths are preferred because they allow production in baskets rather than hangers (this would be the case if impact plating were used). It is understood that the electroless copper solutions of Table 8 with formaldehyde as reducing agents work in an alkaline environment. The novel catalyst is not fully effective in initiating electroless deposition in formaldehyde reduced baths unless the adsorbed palladium compound has previously been reduced to Pd ⁰ .

In method 3, this previous reduction does not carried out. In such conditions, the first must strom loose metallization (step 9) performed in baths who those treated with hypophosphite, borohydride, hydrazine, alkylamine boron or their derivatives have been reduced. The Ni, Co, Au and Ag solutions for electroless plating fit all or part of these categories. Ni poses obviously the best choice, since nickel with the mentioned th reducing agents in a wide range of pH values is working. The reducing agents in these baths seem to cause a reduction of the palladium compound to Pd °.

If you take all the costs into account, the best solution is the use of hypophosphite reduced electroless nickel at a slightly acidic pH (4-5) or in the alkaline range (8-10). Precautions that require low temperatures and other conditions, which are too low concentrations of the deposited with Phosphorus are preferred.

There are a lot of publications and godparents with respect to the electroless deposition of nickel, in which thoroughly explains these problems.

An embodiment of an alkaline Ni-P solution under This is the number of successful formulations tested the following:

NiCl₂ · 6 H₂O - 30 g / l
Sodium citrate - 100 g / l
Ammonium chloride - 20 g / l
Sodium tetraborate - 15 g / l
Sodium hypophosphite - 30 g / l
Purified gum arabic - 2 g / l
2-ethylhexylsodium sulphate (40%) - 0.5 ml / l
pH (adjusted with ammonia) - 8-10
air agitation
Continuous filtration
Temperature - 50-80 °

In Method 3, there is no need for an activity tion step between electroless nickel and de-energized or electrolytic copper. It only has a one-minute Rinsing can be done in tap water.

There is neither between Ni nor the laminated copper yet between the deposited copper and Ni adhesion problems. The dreaded passivation of electroless Ni does not occur on, even then, as the printed circuit boards of a violent Replacement and thermal shock tests were subjected to off assumption of some currentless Ni / P deposits at high Temperatures (90 ° C) and some baths based on Borohydride. In these cases, there was little adhesion pro problems. It must therefore Compatibility always done who when certain electroless nickel species are used.

Although Ni-P formulations give excellent metallization results, it should not be forgotten that after a dive time of one minute a continuous homogeneous layer of Ni over the laminated copper to for starts. This Ni layer can only be 0.1 μm thick However, sufficient to remove a copper during the  to prevent ammoniacal etching. This represents the Main reason why the use of electroless Ni never become popular instead of electroless Cu that is. This problem can be solved by using any electroless Ni formulations are solved here as "Hypophosphite reduced electroless nickel" described become. With these baths, the nickel deposition is above the Copper laminate (i.e., the other area of the printed circuit board than the through holes) even at dive times of 30 mins insignificant, that there is no difficulty, copper with the customary etching solutions, in particular ammoniacal solution conditions to remove. This aspect also represents a we significant innovation dar.

The conditions described above are also on reversible when a conventional catalyst is used (i.e., a Sn / Pd mixed catalyst).

Method 4 allows the reduction of the palladium compound to Pd °, and any formaldehyde-reduced stream Loose copper speaks to the catalytically treated Areas.

The reduction can be a chemical reduction with Help is achieved from a solution that consists of hydrazine, hypo phosphite, borohydride, alkylamine boranes and their derivatives within large ranges of concentrations, working temp temperatures, dipping times and pH values. In the Indeed, this step is not very critical as it is extreme it is easy to reduce Pd (IV) or Pd (II) to Pd °. Below is an example of a reduction solution again given that can be used in this regard:

Dimethylamine borane: range about 1 to about 40 g / L, preferably about 5 g / L
Temperature: about room temperature (20 ° C)
Dive time: about 1 to about 2 minutes.

The reduction to Pd ° occurs almost immediately. If ge If desired, surfactants (as indicated herein) may be added , and / or the pH may be in the range of about 4.0 be set to about 13.0.

Reduction solutions based on borohydride and / or Hydrazine are also effective at room temperature.

The subsequent hot reduction is with sodium hypo Phosphite recommended:

Sodium hypophosphite: range about 5 to about 100 g / l, preferably about 30 g / l
Temperature: about 30 to about 90 ° C, preferably about 50 to about 60 ° C
Dive time: about 1 to about 5 minutes
pH: about 4.5 to about 10.

Conditions for Method 5 in Table 8

In method 5, no electroless solutions after catalytic treatment used to form a hole metallization achieve this. This procedure corresponds in a certain way Way the EE1 procedure, which by the patents of the company Kollmorgen Technologies (US-PS 46 83 036 and GB-PS 21 23 036) is covered.

Although the EE1 process is based on Sn / Pd mixed catalysts ba It should be used as the background for process 5 will see.  

After the catalytic treatment, a Pd ° reduction takes place in a "conditioner" instead of the thiourea or contains a derivative thereof and, for example, the following has the following formulation:

dimethylaminoboran from about 2 to about 50 g / L (10 g / L) thiourea from about 5 to about 50 g / L (25 g / L) Triton X-100 about 0 to about 20 g / l (10 ml / l) pH about 7 to about 12 (9-10) temperature about room temperature (20 ° C) dive time about 2 to about 15 minutes (5 minutes).

The preferred values are given in parentheses.

Obviously, dimethylamine borane can by any one Replaces the above-mentioned reducing agent become.

After immersion in the acidic electrolytic copper must the applied voltage is from about 0.8 to about 1.1 V over 3 until about 4 min. After that, the holes should metalli be siert, and the copper plating can at a usual current density for this method carried out who the.

Tolerance of acidic copper baths over thiourea fabric fluctuates. The implementation of two electrolytic Copper plating steps, separated by a rinse gear, is recommended. The first step is to hole metal (about 3 to about 4 minutes), and the second step serves to reinforce the copper layer. Whenever a bath has been contaminated with thiourea, it must decontaminated or a substitute must be used the.  

Use of the new catalyst in the chemical assembly line metallization

The new catalysts can also be used in other combinations be used, always after a conventional one chemical printed circuit metallization. Such a com Combination combines the use of a reducing agent with electroless nickel. In fact, not all behave electroless nickel solutions with respect to the novel kata lysator equally well. By using a reducing agent (as described in connection with step 9 of method 4) ben), the process is compatible with all stromlo sen nickel baths. Under these conditions (at least at Printed circuit boards) may indicate the use of a copper deposit, which has been carried out electrolessly or electrolytically, not be waived. For another combination fin det the new catalyst (with or without reducing agent) in Combined with hypophosphite reduced electroless Copper use. In this way, the chemical metal reduced to 10 steps as shown in Table 9 provides.

Table 9 Chemical metallization sequence using of the novel catalyst and of Hypo phosphite reduced electroless copper

1. degreasing / conditioning
2. Rinse
3. Rinse
4. Microetching
5. Rinse
6. Preparation for catalytic treatment
7. Catalytic treatment
8. Rinse
9. Electroless copper plating (reduced with hypophosphite)
10. Rinse

The novel selective metallization process

The traditional, for the production of printed circuit boards (under Consideration of all variants) used method is highly developed and widely used but has several disadvantages. A disadvantage is in Use of two metallization process lines that are used in Ver equal to the new method larger investments, more Needlework, more frequent manipulations during the manufacture cycle (quality) and require longer process times.

There are also problems associated with aging and aging Liability of the dry film (the waiting times between the the metallization process lines are relatively short, so that Difficulties in the production occur).

The newly proposed selective metallization process overcomes some of these disadvantages while allowing:
The use of a single metallization process line;
total compatibility with subtractive, semi-additive and fully additive processes and their corresponding minates;
the use of all types of masks (plating resists) and in particular of those which are workable in an aqueous environment;
a guaranteed quality of the final product, which still depends on the type of mask used. This dependency is recognizable with double-sided or multi-layer printed circuit boards.

Description of the new process

The new selective metallization process is in the Ta 10, 11 and 12.

For cleaning, any common technique that is in front of the picture transmission is used. The Ab Radiate with pumice powder is just one example The adaptation to multi-layer manufacturing techniques is a known and the expert.  

Table 10

Representation of the production sequence of double-sided PCBs using the new selective metallization sequence (without dirt removal)

Table 11

Representation of the manufacturing sequence of double-sided printed circuit boards using the new selective metallization sequence (with dirt removal)

Table 12

Simplified representation of the manufacturing sequence of multilayer printed circuit boards using the new selective metallization sequence

The surface preparation work depends on the type of used substrate (epoxy, polyimide, Teflon, etc.) from; However, the invention can be used independently of the Substrate always be carried out because the sequence of Ver driving, the introduction of a conditioning step somewhere between drilling and image transfer (Tables 11 and 12) and the sequence as well as the special properties of the Metallization be considered.  

Generally, for each successive example, assume go that all substrates from the popular Verbundma terial glass fiber / epoxy resin are made. application examples games with respect to other substrates, he below purifies.

Conditioning in the production of double-sided print plates without removing dirt

This method is described in Table 10. The Kondi tioning step is not absolutely necessary, but will especially recommended. As seen from the presentation of the selective Metallization follows, it is in the first step to a degreasing / conditioning step, which, of course, is done in an acidic environment. The conditioning carried out is a weakly acidic conditioning to a catalytic Be safely under optimal selective conditions put. The metallization sequence can be strong negative charges on the hole surface, caused by the Drilling process have been induced to be neutralized. Around to ensure an optimal manufacturing quality (independent from the optimal conditions of the baths), however, the Use of a strong conditioning agent in an alka especially before the image transfer recommended.

Almost any type of conditioner and alkaline Degreasing / conditioning agents that exist in the market is, can be successfully used, for example Shipley's Cuposit Conditioner 1160 (trademark) and Cleaner Conditioner 231 (trademark).  

Although these solutions were designed as immersion solutions, They can also be applied to machines with horizontal conveyors find a solution. In any case, all types of con be tested first, since the spray nozzles may cause uncontrolled foaming. The Ver use of a machine in which the treatment by Dipping, preferably by spraying, is done recommended. An example of a good preparation sequence for the plates after drilling with Shipley's Cleaner Conditioner 231 includes the cleaning or deburring of Plate with a known machine, which is the surface of the Brushed plate automatically and high pressure water jets ge towards the surface. Next is the cleaned or deburred plate arranged in a machine that has a submerged conveyor, which is characterized by a solution of Cleaning conditioner, d. H. Shipley's Cleaner Condi tioner 231, extends, and at a temperature of about 60 ° C, the dive time about five minutes be wearing. The plate is then removed from the submerged conveyor and cleaned with the help of a scrubber, after which ge is dried.

This sequence can be easily automated, with all machines working in tandem to a high To achieve productivity.

For the suppliers should be no problems, their Conditioner to adapt so that they are in any arbitrary working machine. You just have to use their surfactant formulation change the foam control settings.  

Conditioning in the production of multi-layer and double-sided PCB with the removal of contamination

There are four basic methods that are used to remove epoxy Impurities are used by the hole walls: Chromic acid, permanganate, sulfuric acid and plasma. each This method has variants, advantages and disadvantages.

With respect to the new selective metallization process he Demand the preferred steps to remove messiness usually effective conditioning prior to Image transmission. Without such conditioning can a bad catalytic treatment and thus an unzu reaching hole cover occur.

If already have process lines to remove impurities can be installed, conditioning to the end of the Process line are set.

Recommended surface preparation sequences for double-sided and multilayer printed circuit boards are shown in Tables 13 and FIG. 14.

Table 13

Recommended surface preparation sequences for double-sided PCBs with removal of impurities

For double-sided plates, the conditioning times in vary greatly depending on the method used for removing impurities and the used Kon conditioner or degreasing / conditioner. To op To achieve the best metallization results, the Dive times with respect to the conditioner of about 4 min to about 30 min.

Table 14

Recommended surface preparation sequence for multi-layer printed circuit boards

For multilayer printed circuit boards (Table 14) the Konditio tion in exactly the same way. The one The only difference is that due to the etching back usually stronger conditioning agents are required. Depending on the re-etching process and / or the Ver drive to remove impurities as well as the selected The conditioning agents reach optimal times of about 5 until about 30 min.  

Description of the metallization sequence of the new selective proceedings

After the preparation of the surface, the circuit board one after another immersed in a group of solutions, which commonly referred to as "selective metallization" becomes. This critical phase is described in Table 15.

Table 15

Metallization sequence of the new selective process

As shown in Table 15, there is a relevant property This method in its compatibility with all used plating resists, in particular those which are processable in an aqueous environment.  

Therefore, each step is carried out at a pH below 7 leads. Of course, at some steps (i.e., step 1 and 8) worked in a weakly alkaline range who when using other types of plating resists For example, RISTON I dry films, RISTON II and LAMINAR (trademark of Norton Thiokol, Inc.) H or Y. However, the procedure can only be defined here based on their selectivity, they can be used universally, when working in an acid environment.

As shown in Table 15, this leads to selective metallization proceed to a significant reduction in the number the process steps, such as a comparison with Table 16 shows.

Table 16

Conventional PCB metallization process compared to the novel process

New method / conventional method differences

Used solutions in selective metallization sequence Degreasing / conditioning

The degreasing and conditioning steps are with a bath performed as a degreasing or Ent  greasing / conditioning bath can be formulated. in the However, in the first case, it may be necessary to have a neuarti conditioning step prior to copper microetching vorzu see, which is disadvantageous.

In principle, this process can be acidic with any Degreasing / conditioning are performed. Many to However, available solutions can overcondition ning the sensitive surface of the plating resist cause and destroy the selectivity of the process. It Therefore, in some cases compatibility tests should be done between existing products and the selective process be performed.

The degreasing / conditioning solution must be as follows in the To be able to do:

• a) removal of fats, dirt and undeveloped Plating resist residues on the printed circuit board;
• b) removal of a minor oxidation layer of the copper surface;
• c) to apply glass fibers on the surface of the substrate grab and remove silanes (is not indispensable bar, but desirable that the solution for this Purpose is formulated);
• d) neutralization of excess negative upper surface charges in the substrate resin and in particular are present on the hole walls. The conditioning must be so weak that on the plating Resist surface existing electrical balance not changed.

Below are two examples of formulations on the same basis, with the first as a degreasing  medium and the second as degreaser / conditioner was formulated. The concentrations can over ± 10-15% can be varied; the reproduced below Concentrations are preferred values.

degreasing Sodium polyphosphate | 30 g / l Na₂ · EDTA or Na₄ · EDTA 1.5 g / l tripotassium 15 g / l Surfactant on the Antarox (trademark, GAF) BL series 1 g / l Ethoxylated (10 ethoxy) nonylphenol 1 g / l Ammonium 1 g / l pH (adjusted with H₂SO₄) 2.5 temperature 45 ° C dive time about 3 to about 6 minutes (preferably 5 minutes)

Degreasing / conditioner

Copper microetch

The copper microetch can be used with any market solution.

Thus, persulfate solutions, solutions based on H ₂ SO ₄ / H ₂ O ₂ and other solutions can be used. Examples of some products that can be used successfully include:

• - RONETCH BS (trademark, LEA RONAL)
• - PRE-ETCH 746 (trademark, SHIPLEY)
• - PRE-ETCH 748 (trademark, SHIPLEY)

The correct working conditions are specified by the supplier give. The dive times must be set so that one receives a copper microetch of 0.5 to 1 micron.

Preparation for the catalytic treatment (pre-catalytic treatment) and catalytic treatment

Step 9 (pre-catalytic treatment) is not indispensable but it is especially recommended. Through this step is an introduction of the components of the previous Lö avoided in the catalyst.

The solutions used must be exactly the same as in step 3 existing compositions and working conditions ent speak.  

Electroless nickel plating or copper plating

The ESCA EXPS results described here show that Some palladium is present over the plating resist mask that is partly different in one of the substrates oxidation state or the same Oxidationszu stood before, when a reduction to PD ° took place lies. The adsorption of small palladium concentrations on the plating resist surface means that the electroless solution contributes to the selectivity of the process. In fact, the electroless solution must be able to. Be rich with different oxidation states and / or different palladium concentrations to distinguish the. This selectivity ensures a successful Metalli sation on free areas, which is due to the removal of the Plating resist mask are present without an Ab divorce over the plating resist.

As previously explained, only current-reduced Hypo speak phosphite, alkylamine borane, hydrazine and borohydrin baths without a reduction step well on the newly proposed Catalyst on.

The selective process requires that the electroless solution at an acidic pH (preferably <5) works to the To extend compatibility to plating resists, which in an aqueous environment are machinable. Under these Be conditions are the only re-usable in practice hypophosphite and alkylamine boranes. The metals with a practical interest, that de-energized in this way can be divorced, Ni and Cu. At this point in the new selective processes involve the electroless baths preferably the four following groups:

• Ni reduced with alkylamine boranes
• - Cu reduced with alkylamine boranes,
• hypophosphite reduced Ni,
• - In the bath separating Cu / Ni alloys.

Alkylamine borane reduced electroless nickel

Many variants are possible, depending on the selected borane Derivative; Buffers, chelating agents, stabilizers, concentra conditions and operating conditions. With the selective process However, the bath must after completing the compatibility tests selected according to the plating resist used become. Below are three examples of such electroless baths listed:

Embodiment 4 nickel sulphate 25 g / l << Ni metal - 5.2 g / l Succinic acid 20 g / l dimethylamine 1.2 g / l 2-ethylhexylsulphate (40%) 0.5 ml / l Pb (NO₃) ₂ 2.6 mg / l or thiourea 1-2 mg / l or thiourea derivatives (i.e., diphenylthiourea) 2 mg / l pH (adjusted with H₂SO₄ or NaOH) 4.5 temperature 65 ° C

Embodiment 5 nickel sulphate 25 g / l << Ni metal - 5.2 g / l Sodium tetraborate 10 g / l dimethylamine 1.8 g / l to 2 g / l 2-ethylhexylsulphate (40%) 0.5 ml / l Lead acetate (II) 4 mg / l pH (adjusted with H₂SO₄ or NaOH) 4.5 temperature 60 ° C

Embodiment 6 nickel sulphate 25 g / l << Ni metal - 5.2 g / l sodium 15 g / l dimethylamine 2 g / l 2-ethylhexylsulphate (40%) 0.5 ml / l Lead acetate (II) 10 mg / l pH (adjusted with H₂SO₄ or NaOH) 4.5 temperature 55 ° C

All concentrations can be easily increased by ± 10% to be changed. Some attention is for the Steue the concentrations of dimethylamineborane (which in the hydrolyzed recommended pH) and the Sta stabilizer (lead salt or organic sulfur compound) conducive.  

The pH may be from about 4 to about 6, preferably from about 4.5 to about 5.0, and the temperature is around ± 5 ° C and preferably fluctuate by ± 2 ° C.

Embodiment 6 is the preferred formulation for this family of electroless baths, since these at the Her position and when working with lower temperatures can be controlled easily.

Some of the bathrooms have extremely good efficiency other stabilizers, such as:

• a) Other Pb (II) salts or Pb (IV) salts, these Salts on organic acids or mineral acids and especially organic acids;
• b) organic sulfur compounds, such as 2- Mercaptobenzothiazole, L-cysteine and equivalents thereof;
• c) polysaccharides such as gelatin and gum Arabic (the latter is preferred).

In any case, optimal concentrations need to be tested be found (especially with organic sulfur connections), which is one of the specialist knowledge of the average person skilled in the art belongs.

Alkylamine borane reduced electroless copper

The following embodiments show that these Bä which can be well stabilized with cyanide additives and currently the best solution for this aspect of the invention represent. The concentration of the stabilizer can be 30 ppm for solutions that work under heating. Out  obvious reasons are cyanide additives (even minor ones) Additives) not suitable for acidic baths.

Embodiment 7 CuSO₄ · 5 H₂O 2 to about 7 g / L (3 g / L) Quadrol (trademark of BASF WYANDOTTE) 50 to about 250 ml / l (150 ml / l) Tert-butylamineborane 1 to about 3 g / L (2 g / L) sodium cyanide 0 to about 50 mg / L (20 mg / L) pH (adjusted with H₂SO₄) 3.8 to about 5.5 (4.0) Temperature room (20 ° C): up to about 40 ° C (room)

The preferred conditions are given in parentheses.

Embodiment 8 Example 8 is identical to Example 7 except for the following changes Tert-butylamineborane 0.5 to about 2 g / l (especially 1 g / l) Dimethylphenantrolin 10 to about 200 mg / l (especially 100 mg / l)

This example has the advantage of a more consistent solution.

Hypophosphite reduced electroless nickel

In this case are also depending on the out chose concentrations and operating conditions many Variants possible.

Embodiment 9 nickel sulphate 10 to about 50 g / L (25 g / L) Ni - 5.2 g / L ammonium acetate 5 to about 15 g / l (7.5 g / l) Purified gum arabic 0.5 to about 4 g / L (2 g / L) Anionic surfactant (i.e., 2-ethylhexylsulphate, solution at 40%) 0 to about 2 ml / l (0.5 m / l) Lead (as salt, ie acetate) 1 to about 7 mg / L (5 mg / L) sodium 10 to about 20 g / L (15 g / L) pH (adjusted with H₂SO₄ or ammonium hydroxide) 4.0 to about 5.5 (4.5) temperature 60 ° to about 95 ° C (65 ° C)

The preferred values are given in parentheses.

Embodiment 10 nickel sulphate 10 to about 50 g / L (25 g / L) Ni - 5.2 g / L ammonium acetate 1 to about 100 g / L (15 g / L) sodium citrate 0 to about 10 g / L (5 g / L) sodium 25 to about 40 g / L (32 g / L) Purified gum arabic 0.5 to about 4 g / L (2 g / L) Nonionic or anionic surfactant (i.e., 2-ethylhexylsulphate, solution at 40%) 0 to about 2 ml / l (0.5 m / l) Lead (as salt, i.e., Pb (II) or (IV) acetate 1 to about 7 mg / L (5 mg / L) pH (adjusted with H₂SO₄ or NaOH) 4.0 to about 5.5 (4.6) temperature 45 ° to about 70 ° C (55 ° C)

In each of these two examples (reduced with hypophosphite nickel electroless nickel) may be gum arabic by others Polysaccharides, for example various glycogenes, Gelatin, alginates, etc., to be replaced. In the selective However, gum arabic is the easiest to metalize use.

Electroless Ni / Cu baths

The following examples are currently the best Solutions in relation to this aspect of the invention.

Embodiment 11

The composition of Example 6 was the following added components:

CuSO₄ · 5 H₂O | 4 g / l sodium citrate 20 g / l pH 4.5 temperature 40 to about 50 ° C

Embodiment 12

In contrast to Example 11 (reduced with dimethylamine borane tes Bad) gives example 12 a reduced with hypophosphite Solution again.

CuSO₄ · 5 H₂O | 6 g / l NiSO₄ · 7 H₂O 0.6 g / l sodium hypophosphite 30 g / l oxalic acid 12 g / l pH (adjusted with H₂SO₄ or NaOH) 4.5 to about 5.0 temperature 60 to about 65 ° C

The compositions of Examples 11 and 12 may contain surfactants and / or various stabilizers are added.

As explained above, there are many nickel, Nickel / copper or acid electroless copper formulations, which are capable after the catalytic treatment with the catalyst of the invention, the first metallization train.

Nevertheless, the preferred embodiments are for commercial commercial use with alkylamine boranes and with hypophosphite reduced electroless nickel. When alkylamine boranes ver applies, one should pay attention to the following:

• a) Alkylamine boranes are much more expensive than sodium hypo Phosphite (DMAB is about ten times more expensive than Hypo phosphite).
• b) Alkylaminborane be at pH 4.5 to 5.0 hydrolyzed so that in addition to the high cost even in the baths become unstable.
• c) Nickel solutions reduced with alkylamine boranes In some cases, significant Ni deposition occurs over laminated copper so that on Cu (laminate) / Ni (Deposition) / Cu (Deposition) interfaces some Adhesion problems can occur.

However, the latter problems can be caused by burning the Coatings are dissolved after metallization (about 120 ° C over 1 h).

Hypophosphite-reduced nickel is not hydrolysis exposed and thus requires no burning.

For these reasons are reduced with hypophosphite Nickel compositions preferred in commercial Ver drive particularly well reproducible and especially efficient are economical.

Horizontal processing

All the principles set forth above, Formulie ments and process times are based on a vertical verar processing of the plates, as in the metallization of Printed circuit boards is common practice. The ones described here however, new procedures and baths have also been partially tested subjected to horizontal processing. Nor This usually reduces the times considerably Lich, for example, periods of 1 min for the catalytic treatment were achieved.

The new solutions, especially the catalyst, can be used in Promising way within a wide Range of other use cases beyond the range the printed boards go out, are used.

Metallization of plastics

The metallization of plastics (thermosets and thermo plastic) is mainly a problem of adequate Surface preparation to ensure good catalytic treatment  tion and adhesion of the metallic deposits to he rich.

Assuming a correctly performed upper Surface preparation was the novel described here Catalysts on d 07516 00070 552 001000280000000200012000285910740500040 0002004203577 00004 07397iverse plastics with great success tested. They can work in the same way as the cata- Prior art in plastics application Find. Among the tested plastics were the following Epoxy, polyurethanes (RIM), PVC, acrylic resins, polyethers ketone, PTFE, polyimide, polycarbonate and polyacetal. In In some cases, resins were used with or without glass fiber tested. The metallizations were made with Ni or Cu or Ni + Cu or Cu + Ni.

The results show that the solutions in all kinds of plastics can be applied when the upper surface preparation is appropriate.

With the novel catalysts is the selective and not selective metallization of plastics for the following Use cases suitable:

• a) metallization of plastic objects for dekora tive purposes.
• b) metallization of equipment, boxes, components, etc. made of plastics or composite materials, including those for electromagnetic shielding and / or interference suppression.
  The possibility of selective metallization is of great interest.
• c) Many electroless cobalt-phosphorus and nickel-cobalt Phosphorus alloys have good magnetic properties and can with the help of the invention  Procedure for computer storage or magnetic storage drawing media are used.
• d) The selective or non-selective metallization of Printed circuit boards with any plastic or composite substrates that include plastic. Which also includes the metallization of injection molded thermo plastic substrates, the increasing importance he reached.
• e) With the inventive method can be based on electroless Paths gold or palladium for the electronic Industry be applied where a pore-free over train is required. In a similar way can Nickel-molybdenum-boron and nickel-tungsten-boron alloys as a complete or partial replacement for gold the electronic sector.

Metallization of ceramics and glass

The novel catalyst families have also been successful for the metallization of various technical ceramics tested.

In particular, experiments with steatite, alumina, Beryl, borosilicate glass and GREEN TAPE (trademark of Company E.I. DUPONT DE NEMOURS) substrates after curing carried out. As with plastics, metallization hangs adhesion of an appropriate surface preparation for each case.

The results obtained with the novel catalysts show that these are selective or non-selective metals lisierungsverfahren with ceramics or glass substrates can be set. Examples of possible application cases len are:

• a) metallization of ceramic or glassware for decorative purposes.
• b) Metallization of ceramic or glass parts from Aus armor for electromagnetic shielding and / or the suppression of interference.
• c) plating of conductors and even some resistors in the thick film hybrid production.
• d) Production of conductors and resistors in the case of position of thin-film hybrid circuits.

Selective deposition of precious metals

Selective deposition on a currentless path. The novel Catalysts make selective metallization with di Show precious metals, such as Au, Ag, Pd, Pt, pos Lich.

All electroless baths are possible. The plating however, depending on the type, resist masks must pH and the temperature of the solution used become. In addition, it may be necessary to low To enter amounts of stabilizers in the electroless baths lead to a perfect selectivity. Such stabilizers may be Pb, Cd, Hg or Sn salts and / or organic compounds containing sulfur, be, depending on the components of the bath.

One application is the selective gold plating of Silica pads during the manufacture of integrated Circuits. It is therefore possible to use gold "cushions" for the purpose Connecting gold or aluminum wires are used to produce with a small number of steps. SämT Liche formulations can be used for such gold plating baths  used, namely the Okinaka formulations, as well as Modifications like those of Ali and Christie's with little Additions of lead salts (2-10 ppm).

Metallization of anodized aluminum

As explained above, work the novel cata in acidic environments, d. H. at a pH between 4 and 6.5, so that they therefore in Metallisierungsver driving can be used for anodized aluminum, whether these methods are selective or not.

As is known, an anodized layer is chemically pretty sensitive and undergoes extremely rapid decomposition and Dissolution when exposed to extreme pH levels. in the Principle, the anodized layer should not have any pH solutions be exposed outside the range 4.5-9.5. In tradi The metallization of anodized Aluminum by physical processes (vacuum, vaporization etc.) or chemical processes, such as CVD, carried out. The new catalysts make the wet Me Metallization of anodized aluminum is possible with the additional advantage that they have a selective metallization enable (which by physical methods or CVD not easily achieved).

For the metallization of anodized aluminum is the the following sequence of steps is recommended:  

Table 17 Metallization sequence for anodized aluminum

As shown, a degreasing in aqueous solution or by solvents (chlorinated, chlorofluorinated solvents or others). Although not required it is recommended to add cationic surfactants based on the conditioning properties of the degreaser.  

A recommended formulation for this degreasing / Conditioner is reproduced below:

Sodium polyphosphate | 50 g / l sodium 30 g / l EDTA or sodium gluconate 2 g / l to about 10 g / l Triton X-100 2 ml / l Basotronic BVI 2 ml / l pH (adjusted with H₂SO₄) 8.5 temperature Room (20 ° C) up to about 45 ° C

The steps to prepare the catalytic treatment and the catalytic treatment are the same as before Her described compositions. However, a pH Recommended setting between 5.0 and 5.5, which is slightly above the PCB substrates. The first Metallization layer must be de-energized with a nickel or Copper bath or another metal to be deposited, where operated in the bath in a pH range between 5 and 8 becomes. The best results (in terms of cost) were achieved with hypophosphite reduced nickel solutions.

Claims (30)

A process for metallizing a non-metallic substrate with a metal coating, characterized in that a catalyst is combined with the substrate based on the oxides of a noble metal of Group VIII of the Periodic Table to thereby obtain a catalytically treated substrate erhal th, and that the catalytically treated substrate is electrolessly or electrolytically coated with a metal composition to prepare the metal coating on the substrate. 2. The method according to claim 1, characterized ge indicates that it is the step of Reduction of the oxide to a zero valent noble metal Group VIII of the Periodic Table. 3. The method of claim 1 or 2, wherein the substrate partially covered with a coating mask, characterized in that the Catalyst substantially and selectively with the substrate combined while the outer surface of the coating mask is essentially not combined with the catalyst  wherein the metal composition is a selective Me tallüberzug essentially on the areas of Substra tes that have been combined with the catalyst forms while the coating mask is not substantially coated with the metal. 4. The method according to claim 3, characterized ge indicates that it is the step of Re production of the oxide to a zerovalent noble metal Group VIII of the Periodic Table. 5. The method according to any one of the preceding claims, characterized in that the Catalyst a colloidal noble metal oxide based on Oxides of Pd, Pt, Rh or Ir. 6. The method according to any one of the preceding claims, characterized in that the Substrate plastic, ceramic or anodised aluminum is. 7. The method according to any one of claims 2 to 6, characterized in that the Reduction of the oxide to the zerovalent metal durchge This is accomplished by combining the oxide with the metal putting it into contact with the metal Composition around an electroless metal plating bath which contains an aldehyde-free reducing agent. 8. The method according to claim 7, characterized ge indicates that the reducing agents Hypophosphites, borohydrides, hydrazines or aminoboranes.   9. The method according to claim 2, characterized ge indicates that the oxide with the help of reducing chemical reducing agents, these being Reducing agents hypophosphites, borohydrides, hydrazines or Aminoboranes are. 10. The method according to claim 3, characterized ge indicates that the catalyst is such based on the oxides of palladium. 11. The method according to claim 6, characterized ge indicates that the catalyst is such based on the oxides of palladium. 12. The method according to claim 7, characterized ge indicates that the catalyst is such based on the oxides of palladium. 13. The method according to claim 8, characterized ge indicates that the catalyst is such based on the oxides of palladium. 14. The method according to claim 9, characterized ge indicates that the catalyst is such based on the oxides of palladium. 15. The method according to any one of the preceding claims, characterized in that the Substrate is a printed circuit board, the optional passage contains holes. 16. The method according to claim 3, characterized ge indicates that the substrate is a print is plate, which optionally contains through holes.   17. The method according to claim 5, characterized ge indicates that the substrate is a print plate is that optionally contains through holes that the Catalyst such based on the oxides of Palladium is and that the catalytically treated substrate is electrolessly coated with a copper deposit. 18. The method according to claim 5, characterized ge indicates that the substrate is a print plate is that optionally contains through holes that the Catalyst such based on the oxides of Palladium is and that the catalytically treated substrate de-energized with a nickel, copper, cobalt, gold or Silver coating composition or alloys thereof Hypophosphites, borohydrides, hydrazines or amine boranes as Contains reducing agent is coated. 19. The method according to claim 5, characterized ge indicates that the substrate is a print plate is that optionally contains through holes that the Catalyst such based on the oxides of Palladium is and that the catalytically treated substrate is reduced with reducing agents which are Hypophosphites, borohydrides, hydrazines or lower alkyl amine borane, and that the substrate after reduction is electrolytically coated with copper. 20. A catalyst for electroless or electrolytic coating of a non-metallic substrate with a metal composition comprising a colloidal oxide of a Group VIII noble metal of the Periodic Table in combination with

• a) an organic acid of lower molecular weight;
• b) a salt of a Group IA or IIA metal of the Periodic Table of a lower molecular weight organic acid or a halo acid based on fluorine, chlorine or bromine;
• c) optionally a nonionic or anionic surfactant, nicotinic acid, coumarin, adenine, guanidine or hydrogen peroxide;

includes. 21. Catalyst according to claim 20, characterized ge indicates that the noble metal belongs to the group VIII is Pd, Pt, Rh or Ir. 22. A catalyst according to claim 20 or 21, characterized characterized in that it is a colloidal Suspension of an oxide of a Group VIII noble metal of the periodic table in a concentration of about 0.5 to about 2 g / l, with the salt of group IA or IIA in is present in an amount of about 0.5 to about 150 g / l and the pH of the suspension ranges from about 1.0 to about 8.5. 23. Pre-rinse composition for a non-metallic Substrate before the application of a catalyst for a electroless or electrolytic metal coating, in which the catalyst on an oxide of a noble metal of the group VIII of the Periodic Table, thereby ge indicates that it is an organic acid lower molecular weight, a Group IA salt or IIA of lower molecular weight organic acid weight or a halogen acid in a concentration of about 0.5 to about 150 g / l, wherein the acid in a  Amount present, which is sufficient to the pH of the Adjust solution to about 1.0 to about 8.5. 24. A process for preparing a catalyst comprising an oxide of a Group VIII noble metal of the Periodic Table characterized by the steps of:
Dissolving from about 0.5 to about 2.6 g / l of a Group VIII noble metal salt in an aqueous solution, adding a lower molecular weight organic acid group IA or IIA salt in an amount of about 0.5 to about 100 g / l and heating to a temperature of about room temperature to about 100 ° C for a time sufficient for the solution to acquire a brownish-reddish color, and after heating, adjusting the pH to a range of about 1, 0 to about 8.0 with a lower molecular weight organic acid. 25. A process for the preparation of a catalyst concentrate comprising an oxide of a Group VIII noble metal of the periodic table, characterized by the following steps:
Dissolving from about 1.0 to about 30 g / L of a Group VIII noble metal salt in an aqueous solution, adding a lower molecular weight organic acid of a Group IA or IIA salt in an amount of from about 0.5 to about 200 grams and heating to a temperature of from about room temperature to about 100 ° C for a time sufficient for the solution to assume a brown-reddish color, and after heating, adjusting the pH to a range of about 1.0 to about 8.0 with a lower molecular weight organic acid. 26. An electroless nickel coating composition containing Nickel salt in a concentration of about 10 to about 50 g / l, a salt of a group IA or IIA metal of the Periodic table and an organic acid with lower Molecular weight, the salt in a concentration is present, which ranges from about 5 to 50 g / l, and an amine  borane in an amount of about 1.5 to about 3 g / l and a Lead II or lead IV salt stabilizer in an amount of about 2 to about 15 g / l. 27. The composition according to claim 25, characterized characterized in that it optionally a nonionic surfactant or an anionic surfactant in one Amount of about 0.1 to about 1 ml / l contains and a pH from about 4.5 to about 5.2. 28. A solution for cleaning a non-metallic substrate for the subsequent application of a metal coating, characterized in that it contains the following components:

• a) sodium polyphosphate of from about 10 to about 50 g / l,
• b) Na _x EDTA, where x = 2 or 4, from 0 to about 5 g / l,
• c) tripotassium phosphate from about 5 to about 20 g / l,
• d) Antarox BL 300 from about 0.5 to about 2 g / l,
• e) poly (lower alkoxy) nonylphenol surfactant from 0 to about 2 g / l and
• f) Ammonium bifluoride from 0 to about 2 g / l.

29. A solution for cleaning and conditioning a non-metallic substrate prior to the application of a metallic coating on the substrate, characterized in that it contains the following constituents Be:

• a) sodium polyphosphate of from about 10 to about 50 g / l,
• b) Na _x EDTA, where x = 2 or 4, from 0 to about 5 g / l
• c) tripotassium phosphate from about 5 to about 20 g / l,
• d) Antarox BL 300 from about 0.5 to about 2 g / l,
• e) Synperonic MP-10 from 0 to about 2 g / l,
• f) a quaternary ammonium compound based on an imidazole derivative of about 1 to about 5 g / l and
• g) ammonium bifluoride from 0 to about 2 g / l, wherein the pH of the solution is adjusted with a mineral acid in a range of about 1.0 to about 4.0.