Title of Invention	A PROCESS FOR APPLYING A METAL COATING TO A NON-CONDUCTIVE SUBSTRATE AND SOLUTION FOR USE IN SAID PROCESS
Abstract	Described is a new process for applying a metal coating to a non-conductive substrate comprising the steps of (a) contacting the substrate with an activator comprising a noble metal/group TVA metal sol to obtain a treated substrate, (b) contacting said treated substrate with a composition comprising a solution of: (i) a Cu(II), Ag, Au or Ni soluble metal salt or mixtures thereof, (ii) 0.05 to 5 mol/1 of a group IA metal hydroxide and (iii) a complexing agent for an ion of the metal of said metal salt, wherein an iminosuccinic acid or a derivative thereof is used as said complexing agent.

Title of Invention

A PROCESS FOR APPLYING A METAL COATING TO A NON-CONDUCTIVE SUBSTRATE AND SOLUTION FOR USE IN SAID PROCESS

Abstract

Described is a new process for applying a metal coating to a non-conductive substrate comprising the steps of (a) contacting the substrate with an activator comprising a noble metal/group TVA metal sol to obtain a treated substrate, (b) contacting said treated substrate with a composition comprising a solution of: (i) a Cu(II), Ag, Au or Ni soluble metal salt or mixtures thereof, (ii) 0.05 to 5 mol/1 of a group IA metal hydroxide and (iii) a complexing agent for an ion of the metal of said metal salt, wherein an iminosuccinic acid or a derivative thereof is used as said complexing agent.

Full Text	Process for applying a metal coating to a non-conductive substrate Field of the Disclosure The invention relates to a process for applying a metal coating to a non- conductive substrate and to a composition used in this process. Background of the Invention Various methods are known of coating non-conductive surfaces. In wet chemi- cal methods, the surfaces to be metallised are, after an appropriate preliminary treatment, either firstly catalysed and then metallised in an electroless manner and thereafter, if necessary, metallised electrolytically, or are directly electrolyti- cally metallised. Methods according to the first variant with electroless metallisation have, how- ever, proved disadvantageous, as process management of the electroless met- allising bath is difficult, treatment of the waste water from this bath is complex and expensive, and the process is lengthy and thus likewise expensive due to the low deposition speed of the metallising bath. Especially for metal coating of plastic parts, for example for sanitary fittings and for the automobile industry, and of parts which are used as casings for electrical appliances which are screened against electromagnetic radiation, the elec- troless metallising methods are problematic. In treatment of such moulded parts, generally relatively large volumes of the treatment solutions are carried over from one treatment bath into the next, as these have a shape by means of which the treatment solution is transported out of the baths when the parts are lifted out. As electroless metallising baths normally contain considerable quanti- ties of toxic formaldehyde and complex formers which are only removable with difficulty, in their treatment large quantities of these baths are lost and must be disposed of in a complicated manner. For this reason a series of metallising methods was developed, by means of which the non-conductive surfaces could be directly coated with metal without electroless metallisation (see, for example, EP 0 298 298 A2, US 4,919,768, EP 0 320 601 A2, US 3,984,290, EP 0 456 982 A1 and WO 89/08375 A1). In EP 0 616 053 A1 there is disclosed a method for direct metallisation of non- conductive surfaces, in which the surfaces are firstly treated with a cleaner/conditioner solution, thereafter with an activator solution, for example a palladium colloidal solution, stabilised with tin compounds, and are then treated with a solution which contains compounds of a metal which is more noble than tin, as well as an alkali hydroxide and a complex former. Thereafter the surfaces can be treated in a solution containing a reducing agent, and can finally be elec- trolytically metallised. WO 96/29452 concerns a process for the selective or partial electrolytic metalli- sation of surfaces of substrates made from electrically non-conducting materials which for the purpose of the coating process are secured to plastic-coated hold- ing elements. The proposed process involves the following steps: a) preliminary treatment of the surfaces with an etching solution containing chromium (VI) ox- ide; followed immediately by b) treatment of the surfaces with a colloidal acidic solution of paNadium-/tin compounds, care being taken to prevent prior contact with adsorption-promoting solutions; c) treatment of the surfaces with a solution containing a soluble metal compound capable of being reduced by tin (II) com- pounds, an alkali or alkaline earth metal hydroxide, and a complex forming agent for the metal in a quantity sufficient at least to prevent precipitation of metal hydroxides; d) treatment of the surfaces with an electrolytic metallisation solution. The processes described in EP 0 616 053 A1 and WO 96/29452 are disadvan- tageous in that they require the use of a noble metal such as palladium which is a very expensive metal. Hence, it is the object underlying the present invention to provide a process re- quiring a reduced amount of a noble metal such as palladium to activate the surface of the non-conductive substrate to be metal-coated. Summary of the Disclosure This object is achieved by a process for applying a metal coating to a non- conductive substrate comprising the steps of (a) contacting the substrate with an activator comprising a noble metal/group IVA metal sol to obtain a treated substrate, (b) contacting said treated substrate with a composition comprising a solution of: (i) a Cu(ll), Ag, Au or Ni soluble metal salt or mixtures thereof, (ii) 0.05 to 5 mol/l of a group IA metal hydroxide and (iii) a complexing agent for an ion of the metal of said metal salt, wherein iminosuccinic acid or a derivative thereof is used as said complexing agent. Detailed Description of the Invention It has been surprisingly found that the use of iminosuccinic acid or a derivative thereof makes it possible to substantially reduce the amount of noble metal such as palladium in the activator. Suitable iminosuccinic acid derivatives for use in the present invention include those having the formula (I) shown below: wherein R^ is selected from the group consisting of H, Na, K, NH4, Ca, Mg, Li and Fe, R2 is selected from the group consisting of -CH2-COOR1, -CH2-CH2-COOR1, -CH2-CH2-OH, -CH2-CHOH-CH3 and -CH2-CHOH-CH2OH, and R3 is selected from the group consisting of H, -CH2-COOR1, -CH2-CH2-COOR1, -CH2-CH2-OH, -CH2-CHOH-CH3 and -CH2-CHOH-CH2OH. The above mentioned compounds are described in DE 198 50 359 A1. WO 00/26398 describes a method of producing compounds of formula (I) and their mixtures on the basis of carbohydrates by fermentation in the presence of mi- croorganisms. Preferably, the iminosuccinic acid derivative is the iminosuccinic acid sodium salt having the following structural formula: The non-conductive substrates to be coated according to the process of the present invention are not particularly limited. These substrates include plastic parts which are intensely structured, such for example as combs or articles de- signed with a substantial extension in the third dimension, e.g. coffee pots, tele- phone handsets, water pipe fittings, etc. However, also other non-conductive substrates such as ceramic substrates or other metal oxide non-conductive substrates can be coated according to the present invention. In addition, small surfaces such as through-hole walls of printed circuit boards can be coated. The substrate may then optionally be micro-etched with a chemical etchant, where the substrate comprises a non-conductive material having a metal layer on it such as a copper-clad substrate which is employed in the manufacture of circuit boards. An example of such a chemical etchant includes standard etch- ing agents containing a mixture of chromic and sulphuric acid. The micro- etching step is employed in order to prepare the metal layer such as the copper layer portion of the substrate for subsequent electroplating. Acid dips and water rinses may be included after etching. Prior to treating the substrate with an activator, it may be immersed in a com- mercial pre-dip containing NaCI, SnCl2 and HCI, the pH of which is below about 0.5. The substrate then treated with an activator comprising a noble metal/Group IVA metal sol. Noble metals comprise Ag or Au or Group VIII noble metals in- cluding Ru, Rh, Pd, Os, Ir, Pt, or various mixtures of such noble metals. The preferred noble metals are the Group VIII noble metals and especially a metal comprising palladium. The activator of the present invention is prepared in such a fashion so that there is excess Group IVA metal compound reducing agent present, i.e., a stoichiometric excess of reducing agent (e.g., divalent tin) compared to the no- ble metal compound (e.g., divalent Pd) from which the activator is made. In this way the activator such as the Pd/Sn sol has residual divalent Sn that can func- tion as a reducing agent. The Group IVA metals that may be employed include, for example, Ge, Sn and Pb, or mixtures thereof Sn being preferred. The activator preferably will contain a stoichiometric excess of the Group IVA metal as compared to the noble metal. The Group IVA metal is substantially in its lowest oxidation state so that it will be available to reduce the more noble metal salts that are employed in forming the activator. Because it is also em- ployed in a stoichiometric excess based on the salts of the noble metal that are employed to form the activator, the excess of the Group IVA metal in combina- tion with the activator will also be substantially in its lowest oxidation state. The activator thus prepared with the excess of the Group IVA metal in its lowest oxi- dation state will also be available to reduce the Group IB or other more noble metal salts that are subsequently brought into contact with the activator, such as the salts of copper as described herein. The Group IVA metal is preferably employed as a salt, such as a halide and especially a chloride, but in any event, will be present in an amount so that the molar ratio of the Group IVA metal to the noble metal of the activator is from 4:1 to 95:1, especially 10:1 to 55:1 and preferably from 15:1 to 50:1. Some specific Group IVA metal salts that may be used in this regard comprise PbCI2, SnCI2 or a mixture of GeCI2 and GeCI4 dis- solved in dilute hydrochloric acid. The preferred Group IVA metal comprises tin and especially tin in the form of stannous chloride. The preparation of the activator is conventional and is disclosed in United States Patent No. 3,011,920 and United States Patent No. 3,682,671. The treated substrate, after the activator solution has been applied, is rinsed and then treated with the above mentioned composition comprising the Cu(ll), Ag, Au or Ni soluble metal salt, the group IA metal hydroxide and the iminosuc- cinic acid (derivative) as a complexing agent for the ions of the metal of the aforementioned metal salts, comprising Ag+, Ag2+, Au+, Au2+ and Ni2+ salts. Preferably, the metal salt is a Cu(ll) salt. Anywhere from 0.0002 to 0.2 mols/l and especially from 0.004 to 0.01 mols/l of the said metal salt may be employed in the bath where the solvent preferably comprises water. The bath includes a Group IA metal hydroxide in an amount from 0.05 to 5 mol/l, preferably 1 to 3 mol/l and most preferred 1.5 to 2 mol/l. The Group IA metals in this regard comprise Li, Na, K, Rb, Cs or mixtures thereof, especially Li, Na, K and mixtures thereof and preferably a metal comprising Li. The composition used in the process for applying a metal coating to a non- conductive substrate further includes iminosuccinic acid or salt thereof or a de- rivative thereof according to formula (l) above as a complexing agent. The iminosuccinic acid sodium salt can form pentacoordinated complexes. The complex is formed via the nitrogen atom and all four carboxylic groups. Some complex formation constants for various metal ions are shown in the table be- low: The complexing agent is employed in an amount sufficient for the bath to form a thin, dense metal-rich catalytic film on the substrate with sufficient electrical conductivity for subsequent electroplating and at the same time produce rela- tively clean metal surfaces. In general, the complexing agent is used in an amount of 0.005 to 1 mol/l, preferably 0.01 to 0.3 mol/l and most preferably 0.03 to 0.15 mol/l. In addition to the iminosuccinic acid or iminosuccinic acid derivative complexing agent further complexing agents may be used. These further complexing agents are used in general in an amount of 0.05 to 1.0mol/l and preferably 0.2 to 0.5 mol/l. Suitable additional complexing agents include complexing agents se- lected from the group consisting of acetate, acetylacetone, citric acid, 1,2- diaminocyclohexane-N,N,N',N'-tetraacetic acid, dimethylglyoxime (50% diox- ane), 2,2'-dipyridyl, ethanolamine, ethylenediamine, ethylenediamine N.N.N'.N'- tetraacetic acid, glycine, N'-(2-hydroxyethyl)ethylenediamine-N,N,N,-triacetic acid, 8-hydroxy-2-methylquinoline (50% dioxane), 8-hydroxyquinoline-5-sulfonic acid, lactic acid, nitrilotriacetic acid, 1-nitroso-2-naphthol (75% dioxane), ox- alate, 1,10-phenanthroline, phthalic acid, piperidine, propylene-1,2-diamine, pyridine, pyridine-2,6-dicarboxylic acid, 1-(2-pyridylazo)-2-naphthol (PAN), 4-(2- pyridylazo)resorcinal (PAR), pyrocatechol-3,5-disulfonate, 8-quinolinol, sali- cyclic acid, succinic acid, 5-sulfosalicyclic acid, tartaric acid, thioglycolic acid, thiourea, triethanoiamine, triethylenetetramine (trien), 1,1,1-trifluoro-3-2'- thenoylacetone (TTA). The preferred additional complexing agent for copper ions is an alkanolamine comprising for example monoethanolamine. Alkanolamines in addition to monoethanolamine that may be employed in this regard include the following lower alkanolamines: diethanolamine, triethanoiamine, monoisopropanolamine, diisopropanolamine, triisopropanolamine, mono-sec-butanolamine. di-sec- butanolamine, 2-amino-2-methyl-1-propanediol, 2-amino-2-ethyl-1,3-propane- diol, 2-dimethylamino-2-rnethyl-1-propanol, tris(hydroxymethyl)aminomethane, and various mixtures of the alkanolamines. Other weak complexing agents can be used such as other amines, including aliphatic and cyclic, e.g., aromatic amines having up io 10 carbon atoms ali of which are described in Kirk-Othmer, Encyclopedia of Chemical Technology un- der "Amines". Additionally, mono and poly carboxylic acids having up to 8 car- bon atoms and their salts can be used and include amino acids. These acids are also defined in Kirk-Othmer, Id. under "Carboxylic Acids" and "Amino Acids". The preferred acids in this regard include gluconic acid, lactic acid, acetic acid and tartaric acid. The composition for use in the process according to the present invention may preferably be obtained from a kit-of-parts, said kit-of-parts comprising composi- tion (A) and (B) wherein composition (A) comprises: (A1) said iminosuccinic acid or a derivative thereof, (A2) said soluble metal salt and wherein composition (B) comprises: (B1) said group IA metal hydroxide. The use of two components (A) and (B) is advantageous in that component (A) comprises the essential compounds for use in the process according to the pre- sent invention, whereas component (B) is an alkaline solution adjusting the pH of the final composition. The use of such a separate alkaline solution makes it easier to control the alcalinity of the bath under operating conditions. The various anions of the above mentioned water-soluble metal salt include inorganic acid anions or mixtures thereof such as the halogen anions, i.e., F-, CI-, Br- or I-, CI- being especially preferred, sulfate or carbonate anions, lower molecular weight organic acid anions such as formate or acetate anions or sali- cylate anions and the like. Additionally, mixtures of the foregoing anions can be employed as well as salt-like anions such as CuCl22KCI.2H2O, CuCI22NaCI.2H2O and the various art known equivalents thereof. As mentioned above, the use of iminosuccinic acid or a derivative thereof makes it possible to substantially reduce the amount of noble metal such as palladium in the activator. According to the present invention, the activator comprises at least 10 mg/l of palladium as noble metal, preferably 30 - 50 mg/l. According to the prior art processes, such as described in EP-A-0 538 006 or EP-A-0 913 502, the activator requires a much higher concentration in the range of at least 200 mg/l, e.g. 250 mg/l palladium. After contacting with the activator, the substrates are treated with the composi- tion comprising a solution of the Cu(ll), Ag, Au or Ni soluble metal salts or mix- tures thereof, the group IA metal hydroxide and the iminosuccinic acid complex- ing agent, for example, about 10 minutes with the temperature above 60°C. Bath temperature may vary from 49°C to 82°C. Treatment time ranges from 4 to 12 minutes or more which is typical for production purposes, however, may vary out of this range depending on the temperature and condition of the bath. The time used is actually the time necessary to provide the best metal coverage for the formation of the conductive film or to provide minimum required coverage. The conductive film is then electrolytically coated by methods well known in the art. Subsequent electroplating is best achieved if the coating is microetched in an acidic oxidising medium so that the adhesion and morphology of the electrolyti- cally applied metal coating (e.g. copper) is optimised. Microetching is effected by an acidic oxidising agent which is conventional in the art, however, it has been found that even short exposures (e.g. about one-half minute) to the micro- etch solution causes a loss in conductivity and if microetching is carried out over a period of time for about two minutes the coating loses substantially all of its conductivity which indicates it is most likely entirely removed from the substrate. Accordingly, after the substrate has been treated with the copper bath, for ex- ample, it is then preferably rinsed with water and subjected to a neutralisation and reducing bath to eliminate this problem. The neutralisation and reducing bath neutralises the residual alkali on the treated surfaces and also improves the resistance of the conductive film to oxidising chemical micro-etchants. The neutralisation and reducing steps may be conducted separately, i.e., in separate steps employing a first acid neutralisation bath and a second reducing bath. Reducing agents that may be employed in this regard are generally disclosed in United States Patent No. 4,005,051 and EP-A-0 616 053. The treated substrate may then be coated electrolytically with a further or a final metal coating. In other words, the application of the composition as described above to the substrates as defined herein comprises the first step (in a two-step process) for the application of a metal coating to a non-metallic substrate. In this first step, a coating is obtained on the surface of the substrate which signifi- cantly lowers the resistivity of the substrate as compared to the conductivity of the substrate prior to the application of the composition according to the present invention. Thus, the present invention is directed to a two-step process wherein the conductivity is increased initially by applying a very thin metal coating hav- ing a resistivity in the range of about 0.04 to 12 kO/cm and especially 0.8 to 6 kO/cm. The present invention is further illustrated by the following examples. Example 1 Two compositions (A) and (B) were prepared as shown below: Composition (A): (A1) according to Table 1 below, (A2) about 4.0% by weight CuSO4- 5H2O, (A3) according to Table 1 below, (A4) optionally about 0.01% by weight of a tenside, the remainder being water. Composition (B): (B1) 6.0% by weight sodium hydroxide, (B2) 9.0% by weight lithium hydroxide, the remainder being water. The pH of composition (A) was 4.1 and its density 1.2053 g/cm3. The pH of composition (B) was 13 and its density 1.12 g/cm3. 90 ml/l of composition (A) and 300 ml/I of composition (B) were mixed to obtain a bath comprising the above mentioned components and ingredients. In total, four baths were prepared comprising the amounts of complexing agents as shown in Table 1 below. Plates made of ABS (Novodur P2MC) were treated with an etching solution containing chrome (VI) oxide for 10 minutes at a temperature of 70°C. After a rinsing treatment, chrome (VI) compounds adhering to the substrate surfaces were reduced to chrome (III) compounds by treating the substrate with a reduc- ing agent for one minute at room temperature. After a further rinsing treatment, the substrate was treated in a solution for three minutes at 40oC, the solution being composed as follows: Activator: Colloidal solution containing 40 mg/l palladium as palladium chloride (much less than conventionally used: 200 gm/l Pd), 35 g/l stannous chloride (18.5 g/l Sn) and 350 ml/l hydrochloric acid with a pH of 1 or less for 4 minutes. After the activator treatment, the substrate was again rinsed. After the rinsing treatment, the substrate was immersed into the bath obtained from compositions (A) and (B) described above comprising the complexing agent in the amounts described in Table 1 below. Table 1 also lists the results of measurements relating to the amount of palladium, tin and copper adsorbed onto the surface of the substrate depending upon the amount of complexing agent used. The experiments further showed that the use of the iminosuccinic acid complex- ing agent made it possible to obtain fully metal-coated HBS plates at the palla- dium concentrations mentioned above. Further, a comparison between the solutions obtained by removing the metal coatings from the ABS surfaces shows that the surface that has been treated with the iminosuccinic acid complexing agent has a significantly higher copper concentration at a reduced palladium concentration in the activator as well as a lower tin concentration. Finally, a comparison between compositions with and without iminosuccinic acid complexing agent added shows that those substrate surfaces which have not been treated with the complexing agent have less copper so that a complete coating is not obtained. The results obtained in Example 1 are summarised in Table 1 below. Table 1: Results of adsorption measurements on surfaces obtained with activa- tor AKI (40 mg/l palladium) It is apparent from the experimental results described above that the use of the iminosuccinic acid complexing agent results in a significant higher deposition of copper metal on the substrate surface in the Cu-Link step. In this experiment the overall molar content of complexing agent is kept constant to better com- pare the results. The metallic copper is deposited by a redox reaction in ex- change of Sn: The oxidised Sn2+ ions are dissolved in the solution. Therefore, a increase deposition of Cu(0) results in a decreased amount of absorbed Sn(0), which also becomes apparent from Table 1. The process involving the use of this complexing agent can be carried out at a concentration as low as 40 to 50 mg/l of Pd in the activator. According to the prior art processes, a concentration of at least 150 mg/l Pd in the activator is required. The solution comprising the iminosuccinic acid complexing agent can be pre- pared more easily than the prior art complexing solutions and, finally, their long- term stability in respect of carbonate formation is increased. The higher amount of metallic Cu (0) absorbed on the substrate surface results in an excellent final metal coating deposited thereon. A treatment using baths 1 and 3 shown in Table 1 in contrast does not result in a completely metallised surface of the non-conductive surface. Example 2 The following experiment was performed to show the superior metallisation re- sults: The substrates treated with the baths listed in Table 1 were washed with water and then subjected to a subsequent copper electroplating step. A commercially available copper electroplating bath Cupracid® HT (Atotech Deutschland GmbH) was used, which contains 250 g/l copper sulfate, 50 g/l sulphuric acid, 50 ppm chloride ions and a brightening agent. The electroplating operation was performed at a plating solution temperature of 25°C and a current density of 3 A/dm2 for 15 min. Metallisation result: Bath 1: Poor: Incomplete coverage of the surface with copper Bath 2: Good: Complete coverage of the surface with copper Bath 3: Poor: Incomplete coverage of the surface with copper Bath 4: Good: Complete coverage of the surface with copper CLAIMS 1. A process for applying a metal coating to a non-conductive substrate com- prising the steps of (a) contacting the substrate with an activator comprising a noble metal/group IVA metal sol to obtain a treated substrate, (b) contacting said treated substrate with a composition comprising a so- lution of: (i) a Cu(ll), Ag, Au or Ni soluble metal salt or mixtures thereof, (ii) 0.05 to 5 mol/l of a group IA metal hydroxide and (iii) a complexing agent for an ion of the metal of said metal salt, characterised in that iminosuccinic acid or a derivative thereof is used as said complexing agent. 2. The process according to claim 1 wherein the composition further com- prises a second complexing agent in addition to the iminosuccinic acid or its derivative. 3. The process according to claim 1 wherein the complexing agent is used in an amount of 0.005 to 1 mol/l. 4. The process according to claim 2 or 3 wherein the second complexing agent is used in an amount of 0.05 to 1.0 mol/l. 5. The process according to claim 4 wherein the second complexing agent is used in an amount of 0.2 to 0.5 mol/l. 6. The process according to claim 5 wherein the second complexing agent is selected from the group consisting of gluconic acid, lactic acid, acetic acid and tartaric acid and salts thereof. 7. The process of claim 1 wherein the composition is obtained from a kit-of- parts, said kit-of-parts comprising composition (A) and (B) wherein compo- sition (A) comprises: (A1) said iminosuccinic acid or a derivative thereof, (A2) said soluble metal salt and wherein composition (B) comprises: (B1) said group IA metal hydroxide. 8. A composition for use in a process for applying a metal coating to a non- conductive substrate comprising (i) a Cu(ll), Ag, Au or Ni soluble metal salt or mixtures thereof, (ii) iminosuccinic acid or a derivative thereof. 9. The composition according to claim 8 further comprising 0.05 to 5 mol/l of a group IA metal hydroxide. 10. The composition according to claim 8 or 9 wherein the iminosuccinic acid derivative has the formula (I): wherein R1 is selected from the group consisting of H, Na, K, NH4, Ca, Mg, Li and Fe, R2 is selected from the group consisting of -CH2-COOR1, -CH2-CH2-COOR1, -CH2-CH2-OH, -CH2-CHOH-CH3 and -CH2-CHOH-CH2OH, and R3 is selected from the group consisting of H, -CH2-COOR1, -CH2-CH2-COOR1, -CH2-CH2-OH, -CH2-CHOH-CH3 and -CH2-CHOH-CH2OH. 11. The composition according to claims 8 to 10 further comprising a second complexing agent selected from the group consisting of acetate, acetylace- tone, citric acid, 1,2-diaminocyclohexane-N,N,N',N'-tetraacetic acid, di- methylglyoxime (50% dioxane), 2,2'-dipyridyl, ethanolamine, ethylenedia- mine, ethylenediamine N.N.N'.N'-tetraacetic acid, glycine, N'-(2- hydroxyethyl)ethylenediamine-N,N,N'-triacetic acid, 8-hydroxy-2-methyl- quinoline (50% dioxane), 8-hydroxyquinoline-5-sulfonic acid, lactic acid, ni- trilotriacetic acid, 1 -nitroso-2-naphthol (75% dioxane), oxalate, 1,10- phenanthroline, phthalic acid, piperidine, propylene-1,2-diamine, pyridine, pyridine-2,6-dicarboxyiic acid, 1-(2-pyridylazo)-2-naphthol (PAN), 4-(2- pyridylazo)resorcinal (PAR), pyrocatechol-3,5-disulfonate, 8-quinolinoi, salicyciic acid, succinic acid, 5-sulfosalicyclic acid, tartaric acid, thioglycolic acid, thiourea, triethanolamine, triethylenetetramine (trien), 1,1,1-trifluoro- 3-2'-thenoylacetone (TTA) in an amount of 0.05 to 1.0 mol/l. 12. The composition according to claim 11 comprising the further complexing agent in an amount of 0.2 to 0.5 mol/l. 13. The composition according to claim 12 wherein the further complexing agent is selected from the group consisting of gluconic acid, lactic acid, acetic acid and tartaric acid and salts thereof. Described is a new process for applying a metal coating to a non-conductive substrate comprising the steps of (a) contacting the substrate with an activator comprising a noble metal/group TVA metal sol to obtain a treated substrate, (b) contacting said treated substrate with a composition comprising a solution of: (i) a Cu(II), Ag, Au or Ni soluble metal salt or mixtures thereof, (ii) 0.05 to 5 mol/1 of a group IA metal hydroxide and (iii) a complexing agent for an ion of the metal of said metal salt, wherein an iminosuccinic acid or a derivative thereof is used as said complexing agent.

Full Text

Process for applying a metal coating to a non-conductive substrate
Field of the Disclosure
The invention relates to a process for applying a metal coating to a non-
conductive substrate and to a composition used in this process.
Background of the Invention
Various methods are known of coating non-conductive surfaces. In wet chemi-
cal methods, the surfaces to be metallised are, after an appropriate preliminary
treatment, either firstly catalysed and then metallised in an electroless manner
and thereafter, if necessary, metallised electrolytically, or are directly electrolyti-
cally metallised.
Methods according to the first variant with electroless metallisation have, how-
ever, proved disadvantageous, as process management of the electroless met-
allising bath is difficult, treatment of the waste water from this bath is complex
and expensive, and the process is lengthy and thus likewise expensive due to
the low deposition speed of the metallising bath.
Especially for metal coating of plastic parts, for example for sanitary fittings and
for the automobile industry, and of parts which are used as casings for electrical
appliances which are screened against electromagnetic radiation, the elec-
troless metallising methods are problematic. In treatment of such moulded
parts, generally relatively large volumes of the treatment solutions are carried
over from one treatment bath into the next, as these have a shape by means of
which the treatment solution is transported out of the baths when the parts are
lifted out. As electroless metallising baths normally contain considerable quanti-
ties of toxic formaldehyde and complex formers which are only removable with
difficulty, in their treatment large quantities of these baths are lost and must be
disposed of in a complicated manner.
For this reason a series of metallising methods was developed, by means of
which the non-conductive surfaces could be directly coated with metal without
electroless metallisation (see, for example, EP 0 298 298 A2, US 4,919,768, EP
0 320 601 A2, US 3,984,290, EP 0 456 982 A1 and WO 89/08375 A1).
In EP 0 616 053 A1 there is disclosed a method for direct metallisation of non-
conductive surfaces, in which the surfaces are firstly treated with a
cleaner/conditioner solution, thereafter with an activator solution, for example a
palladium colloidal solution, stabilised with tin compounds, and are then treated
with a solution which contains compounds of a metal which is more noble than
tin, as well as an alkali hydroxide and a complex former. Thereafter the surfaces
can be treated in a solution containing a reducing agent, and can finally be elec-
trolytically metallised.
WO 96/29452 concerns a process for the selective or partial electrolytic metalli-
sation of surfaces of substrates made from electrically non-conducting materials
which for the purpose of the coating process are secured to plastic-coated hold-
ing elements. The proposed process involves the following steps: a) preliminary
treatment of the surfaces with an etching solution containing chromium (VI) ox-
ide; followed immediately by b) treatment of the surfaces with a colloidal acidic
solution of paNadium-/tin compounds, care being taken to prevent prior contact
with adsorption-promoting solutions; c) treatment of the surfaces with a solution
containing a soluble metal compound capable of being reduced by tin (II) com-
pounds, an alkali or alkaline earth metal hydroxide, and a complex forming
agent for the metal in a quantity sufficient at least to prevent precipitation of
metal hydroxides; d) treatment of the surfaces with an electrolytic metallisation
solution.
The processes described in EP 0 616 053 A1 and WO 96/29452 are disadvan-
tageous in that they require the use of a noble metal such as palladium which is
a very expensive metal.
Hence, it is the object underlying the present invention to provide a process re-
quiring a reduced amount of a noble metal such as palladium to activate the
surface of the non-conductive substrate to be metal-coated.
Summary of the Disclosure
This object is achieved by a process for applying a metal coating to a non-
conductive substrate comprising the steps of
(a) contacting the substrate with an activator comprising a noble metal/group
IVA metal sol to obtain a treated substrate,
(b) contacting said treated substrate with a composition comprising a solution
of:
(i) a Cu(ll), Ag, Au or Ni soluble metal salt or mixtures thereof,
(ii) 0.05 to 5 mol/l of a group IA metal hydroxide and
(iii) a complexing agent for an ion of the metal of said metal salt,
wherein iminosuccinic acid or a derivative thereof is used as said complexing
agent.
Detailed Description of the Invention
It has been surprisingly found that the use of iminosuccinic acid or a derivative
thereof makes it possible to substantially reduce the amount of noble metal
such as palladium in the activator.
Suitable iminosuccinic acid derivatives for use in the present invention include
those having the formula (I) shown below:

wherein R^ is selected from the group consisting of H, Na, K, NH4, Ca, Mg, Li
and Fe,
R2 is selected from the group consisting of

-CH2-COOR1, -CH2-CH2-COOR1, -CH2-CH2-OH, -CH2-CHOH-CH3 and
-CH2-CHOH-CH2OH, and
R3 is selected from the group consisting of H, -CH2-COOR1, -CH2-CH2-COOR1,
-CH2-CH2-OH, -CH2-CHOH-CH3 and -CH2-CHOH-CH2OH.
The above mentioned compounds are described in DE 198 50 359 A1. WO
00/26398 describes a method of producing compounds of formula (I) and their
mixtures on the basis of carbohydrates by fermentation in the presence of mi-
croorganisms.
Preferably, the iminosuccinic acid derivative is the iminosuccinic acid sodium
salt having the following structural formula:

The non-conductive substrates to be coated according to the process of the
present invention are not particularly limited. These substrates include plastic
parts which are intensely structured, such for example as combs or articles de-
signed with a substantial extension in the third dimension, e.g. coffee pots, tele-
phone handsets, water pipe fittings, etc. However, also other non-conductive
substrates such as ceramic substrates or other metal oxide non-conductive
substrates can be coated according to the present invention. In addition, small
surfaces such as through-hole walls of printed circuit boards can be coated.
The substrate may then optionally be micro-etched with a chemical etchant,
where the substrate comprises a non-conductive material having a metal layer
on it such as a copper-clad substrate which is employed in the manufacture of
circuit boards. An example of such a chemical etchant includes standard etch-
ing agents containing a mixture of chromic and sulphuric acid. The micro-
etching step is employed in order to prepare the metal layer such as the copper
layer portion of the substrate for subsequent electroplating. Acid dips and water
rinses may be included after etching.
Prior to treating the substrate with an activator, it may be immersed in a com-
mercial pre-dip containing NaCI, SnCl2 and HCI, the pH of which is below about
0.5.
The substrate then treated with an activator comprising a noble metal/Group
IVA metal sol. Noble metals comprise Ag or Au or Group VIII noble metals in-
cluding Ru, Rh, Pd, Os, Ir, Pt, or various mixtures of such noble metals. The
preferred noble metals are the Group VIII noble metals and especially a metal
comprising palladium.
The activator of the present invention is prepared in such a fashion so that there
is excess Group IVA metal compound reducing agent present, i.e., a
stoichiometric excess of reducing agent (e.g., divalent tin) compared to the no-
ble metal compound (e.g., divalent Pd) from which the activator is made. In this
way the activator such as the Pd/Sn sol has residual divalent Sn that can func-
tion as a reducing agent.
The Group IVA metals that may be employed include, for example, Ge, Sn and
Pb, or mixtures thereof Sn being preferred.
The activator preferably will contain a stoichiometric excess of the Group IVA
metal as compared to the noble metal. The Group IVA metal is substantially in
its lowest oxidation state so that it will be available to reduce the more noble
metal salts that are employed in forming the activator. Because it is also em-
ployed in a stoichiometric excess based on the salts of the noble metal that are
employed to form the activator, the excess of the Group IVA metal in combina-
tion with the activator will also be substantially in its lowest oxidation state. The
activator thus prepared with the excess of the Group IVA metal in its lowest oxi-
dation state will also be available to reduce the Group IB or other more noble
metal salts that are subsequently brought into contact with the activator, such
as the salts of copper as described herein. The Group IVA metal is preferably
employed as a salt, such as a halide and especially a chloride, but in any event,
will be present in an amount so that the molar ratio of the Group IVA metal to
the noble metal of the activator is from 4:1 to 95:1, especially 10:1 to 55:1 and
preferably from 15:1 to 50:1. Some specific Group IVA metal salts that may be
used in this regard comprise PbCI2, SnCI2 or a mixture of GeCI2 and GeCI4 dis-
solved in dilute hydrochloric acid. The preferred Group IVA metal comprises tin
and especially tin in the form of stannous chloride.
The preparation of the activator is conventional and is disclosed in United
States Patent No. 3,011,920 and United States Patent No. 3,682,671.
The treated substrate, after the activator solution has been applied, is rinsed
and then treated with the above mentioned composition comprising the Cu(ll),
Ag, Au or Ni soluble metal salt, the group IA metal hydroxide and the iminosuc-
cinic acid (derivative) as a complexing agent for the ions of the metal of the
aforementioned metal salts, comprising Ag+, Ag2+, Au+, Au2+ and Ni2+ salts.
Preferably, the metal salt is a Cu(ll) salt.
Anywhere from 0.0002 to 0.2 mols/l and especially from 0.004 to 0.01 mols/l of
the said metal salt may be employed in the bath where the solvent preferably
comprises water.
The bath includes a Group IA metal hydroxide in an amount from 0.05 to
5 mol/l, preferably 1 to 3 mol/l and most preferred 1.5 to 2 mol/l. The Group IA
metals in this regard comprise Li, Na, K, Rb, Cs or mixtures thereof, especially
Li, Na, K and mixtures thereof and preferably a metal comprising Li.
The composition used in the process for applying a metal coating to a non-
conductive substrate further includes iminosuccinic acid or salt thereof or a de-
rivative thereof according to formula (l) above as a complexing agent.
The iminosuccinic acid sodium salt can form pentacoordinated complexes. The
complex is formed via the nitrogen atom and all four carboxylic groups. Some
complex formation constants for various metal ions are shown in the table be-
low:

The complexing agent is employed in an amount sufficient for the bath to form a
thin, dense metal-rich catalytic film on the substrate with sufficient electrical
conductivity for subsequent electroplating and at the same time produce rela-
tively clean metal surfaces. In general, the complexing agent is used in an
amount of 0.005 to 1 mol/l, preferably 0.01 to 0.3 mol/l and most preferably 0.03
to 0.15 mol/l.
In addition to the iminosuccinic acid or iminosuccinic acid derivative complexing
agent further complexing agents may be used. These further complexing agents
are used in general in an amount of 0.05 to 1.0mol/l and preferably 0.2 to
0.5 mol/l. Suitable additional complexing agents include complexing agents se-
lected from the group consisting of acetate, acetylacetone, citric acid, 1,2-
diaminocyclohexane-N,N,N',N'-tetraacetic acid, dimethylglyoxime (50% diox-
ane), 2,2'-dipyridyl, ethanolamine, ethylenediamine, ethylenediamine N.N.N'.N'-
tetraacetic acid, glycine, N'-(2-hydroxyethyl)ethylenediamine-N,N,N,-triacetic
acid, 8-hydroxy-2-methylquinoline (50% dioxane), 8-hydroxyquinoline-5-sulfonic
acid, lactic acid, nitrilotriacetic acid, 1-nitroso-2-naphthol (75% dioxane), ox-
alate, 1,10-phenanthroline, phthalic acid, piperidine, propylene-1,2-diamine,
pyridine, pyridine-2,6-dicarboxylic acid, 1-(2-pyridylazo)-2-naphthol (PAN), 4-(2-
pyridylazo)resorcinal (PAR), pyrocatechol-3,5-disulfonate, 8-quinolinol, sali-
cyclic acid, succinic acid, 5-sulfosalicyclic acid, tartaric acid, thioglycolic acid,
thiourea, triethanoiamine, triethylenetetramine (trien), 1,1,1-trifluoro-3-2'-
thenoylacetone (TTA).
The preferred additional complexing agent for copper ions is an alkanolamine
comprising for example monoethanolamine. Alkanolamines in addition to
monoethanolamine that may be employed in this regard include the following
lower alkanolamines: diethanolamine, triethanoiamine, monoisopropanolamine,
diisopropanolamine, triisopropanolamine, mono-sec-butanolamine. di-sec-
butanolamine, 2-amino-2-methyl-1-propanediol, 2-amino-2-ethyl-1,3-propane-
diol, 2-dimethylamino-2-rnethyl-1-propanol, tris(hydroxymethyl)aminomethane,
and various mixtures of the alkanolamines.
Other weak complexing agents can be used such as other amines, including
aliphatic and cyclic, e.g., aromatic amines having up io 10 carbon atoms ali of
which are described in Kirk-Othmer, Encyclopedia of Chemical Technology un-
der "Amines". Additionally, mono and poly carboxylic acids having up to 8 car-
bon atoms and their salts can be used and include amino acids. These acids
are also defined in Kirk-Othmer, Id. under "Carboxylic Acids" and "Amino Acids".
The preferred acids in this regard include gluconic acid, lactic acid, acetic acid
and tartaric acid.
The composition for use in the process according to the present invention may
preferably be obtained from a kit-of-parts, said kit-of-parts comprising composi-
tion (A) and (B) wherein composition (A) comprises:
(A1) said iminosuccinic acid or a derivative thereof,
(A2) said soluble metal salt
and wherein composition (B) comprises:
(B1) said group IA metal hydroxide.
The use of two components (A) and (B) is advantageous in that component (A)
comprises the essential compounds for use in the process according to the pre-
sent invention, whereas component (B) is an alkaline solution adjusting the pH
of the final composition. The use of such a separate alkaline solution makes it
easier to control the alcalinity of the bath under operating conditions.
The various anions of the above mentioned water-soluble metal salt include
inorganic acid anions or mixtures thereof such as the halogen anions, i.e., F-,
CI-, Br- or I-, CI- being especially preferred, sulfate or carbonate anions, lower
molecular weight organic acid anions such as formate or acetate anions or sali-
cylate anions and the like. Additionally, mixtures of the foregoing anions can be
employed as well as salt-like anions such as CuCl22KCI.2H2O,
CuCI22NaCI.2H2O and the various art known equivalents thereof.
As mentioned above, the use of iminosuccinic acid or a derivative thereof
makes it possible to substantially reduce the amount of noble metal such as
palladium in the activator.
According to the present invention, the activator comprises at least 10 mg/l of
palladium as noble metal, preferably 30 - 50 mg/l.
According to the prior art processes, such as described in EP-A-0 538 006 or
EP-A-0 913 502, the activator requires a much higher concentration in the
range of at least 200 mg/l, e.g. 250 mg/l palladium.
After contacting with the activator, the substrates are treated with the composi-
tion comprising a solution of the Cu(ll), Ag, Au or Ni soluble metal salts or mix-
tures thereof, the group IA metal hydroxide and the iminosuccinic acid complex-
ing agent, for example, about 10 minutes with the temperature above 60°C.
Bath temperature may vary from 49°C to 82°C. Treatment time ranges from 4 to
12 minutes or more which is typical for production purposes, however, may vary
out of this range depending on the temperature and condition of the bath. The
time used is actually the time necessary to provide the best metal coverage for
the formation of the conductive film or to provide minimum required coverage.
The conductive film is then electrolytically coated by methods well known in the
art.
Subsequent electroplating is best achieved if the coating is microetched in an
acidic oxidising medium so that the adhesion and morphology of the electrolyti-
cally applied metal coating (e.g. copper) is optimised. Microetching is effected
by an acidic oxidising agent which is conventional in the art, however, it has
been found that even short exposures (e.g. about one-half minute) to the micro-
etch solution causes a loss in conductivity and if microetching is carried out over
a period of time for about two minutes the coating loses substantially all of its
conductivity which indicates it is most likely entirely removed from the substrate.
Accordingly, after the substrate has been treated with the copper bath, for ex-
ample, it is then preferably rinsed with water and subjected to a neutralisation
and reducing bath to eliminate this problem. The neutralisation and reducing
bath neutralises the residual alkali on the treated surfaces and also improves
the resistance of the conductive film to oxidising chemical micro-etchants.
The neutralisation and reducing steps may be conducted separately, i.e., in
separate steps employing a first acid neutralisation bath and a second reducing
bath.
Reducing agents that may be employed in this regard are generally disclosed in
United States Patent No. 4,005,051 and EP-A-0 616 053.
The treated substrate may then be coated electrolytically with a further or a final
metal coating. In other words, the application of the composition as described
above to the substrates as defined herein comprises the first step (in a two-step
process) for the application of a metal coating to a non-metallic substrate. In this
first step, a coating is obtained on the surface of the substrate which signifi-
cantly lowers the resistivity of the substrate as compared to the conductivity of
the substrate prior to the application of the composition according to the present
invention. Thus, the present invention is directed to a two-step process wherein
the conductivity is increased initially by applying a very thin metal coating hav-
ing a resistivity in the range of about 0.04 to 12 kO/cm and especially 0.8 to
6 kO/cm.
The present invention is further illustrated by the following examples.
Example 1
Two compositions (A) and (B) were prepared as shown below:
Composition (A):
(A1) according to Table 1 below,
(A2) about 4.0% by weight CuSO4- 5H2O,
(A3) according to Table 1 below,
(A4) optionally about 0.01% by weight of a tenside,
the remainder being water.
Composition (B):
(B1) 6.0% by weight sodium hydroxide,
(B2) 9.0% by weight lithium hydroxide,
the remainder being water.
The pH of composition (A) was 4.1 and its density 1.2053 g/cm3. The pH of
composition (B) was 13 and its density 1.12 g/cm3.
90 ml/l of composition (A) and 300 ml/I of composition (B) were mixed to obtain
a bath comprising the above mentioned components and ingredients.
In total, four baths were prepared comprising the amounts of complexing agents
as shown in Table 1 below.
Plates made of ABS (Novodur P2MC) were treated with an etching solution
containing chrome (VI) oxide for 10 minutes at a temperature of 70°C. After a
rinsing treatment, chrome (VI) compounds adhering to the substrate surfaces
were reduced to chrome (III) compounds by treating the substrate with a reduc-
ing agent for one minute at room temperature.
After a further rinsing treatment, the substrate was treated in a solution for three
minutes at 40oC, the solution being composed as follows: Activator: Colloidal
solution containing 40 mg/l palladium as palladium chloride (much less than
conventionally used: 200 gm/l Pd), 35 g/l stannous chloride (18.5 g/l Sn) and
350 ml/l hydrochloric acid with a pH of 1 or less for 4 minutes.
After the activator treatment, the substrate was again rinsed.
After the rinsing treatment, the substrate was immersed into the bath obtained
from compositions (A) and (B) described above comprising the complexing
agent in the amounts described in Table 1 below. Table 1 also lists the results
of measurements relating to the amount of palladium, tin and copper adsorbed
onto the surface of the substrate depending upon the amount of complexing
agent used.
The experiments further showed that the use of the iminosuccinic acid complex-
ing agent made it possible to obtain fully metal-coated HBS plates at the palla-
dium concentrations mentioned above.
Further, a comparison between the solutions obtained by removing the metal
coatings from the ABS surfaces shows that the surface that has been treated
with the iminosuccinic acid complexing agent has a significantly higher copper
concentration at a reduced palladium concentration in the activator as well as a
lower tin concentration.
Finally, a comparison between compositions with and without iminosuccinic acid
complexing agent added shows that those substrate surfaces which have not
been treated with the complexing agent have less copper so that a complete
coating is not obtained.
The results obtained in Example 1 are summarised in Table 1 below.
Table 1: Results of adsorption measurements on surfaces obtained with activa-
tor AKI (40 mg/l palladium)

It is apparent from the experimental results described above that the use of the
iminosuccinic acid complexing agent results in a significant higher deposition of
copper metal on the substrate surface in the Cu-Link step. In this experiment
the overall molar content of complexing agent is kept constant to better com-
pare the results. The metallic copper is deposited by a redox reaction in ex-
change of Sn:

The oxidised Sn2+ ions are dissolved in the solution. Therefore, a increase
deposition of Cu(0) results in a decreased amount of absorbed Sn(0), which
also becomes apparent from Table 1.
The process involving the use of this complexing agent can be carried out at a
concentration as low as 40 to 50 mg/l of Pd in the activator. According to the
prior art processes, a concentration of at least 150 mg/l Pd in the activator is
required.
The solution comprising the iminosuccinic acid complexing agent can be pre-
pared more easily than the prior art complexing solutions and, finally, their long-
term stability in respect of carbonate formation is increased.
The higher amount of metallic Cu (0) absorbed on the substrate surface results
in an excellent final metal coating deposited thereon. A treatment using baths 1
and 3 shown in Table 1 in contrast does not result in a completely metallised
surface of the non-conductive surface.
Example 2
The following experiment was performed to show the superior metallisation re-
sults:
The substrates treated with the baths listed in Table 1 were washed with water
and then subjected to a subsequent copper electroplating step. A commercially
available copper electroplating bath Cupracid® HT (Atotech Deutschland
GmbH) was used, which contains 250 g/l copper sulfate, 50 g/l sulphuric acid,
50 ppm chloride ions and a brightening agent.
The electroplating operation was performed at a plating solution temperature of
25°C and a current density of 3 A/dm2 for 15 min.
Metallisation result:
Bath 1: Poor: Incomplete coverage of the surface with copper
Bath 2: Good: Complete coverage of the surface with copper
Bath 3: Poor: Incomplete coverage of the surface with copper
Bath 4: Good: Complete coverage of the surface with copper
CLAIMS
1. A process for applying a metal coating to a non-conductive substrate com-
prising the steps of
(a) contacting the substrate with an activator comprising a noble
metal/group IVA metal sol to obtain a treated substrate,
(b) contacting said treated substrate with a composition comprising a so-
lution of:
(i) a Cu(ll), Ag, Au or Ni soluble metal salt or mixtures thereof,
(ii) 0.05 to 5 mol/l of a group IA metal hydroxide and
(iii) a complexing agent for an ion of the metal of said metal salt,
characterised in that iminosuccinic acid or a derivative thereof is used as
said complexing agent.
2. The process according to claim 1 wherein the composition further com-
prises a second complexing agent in addition to the iminosuccinic acid or
its derivative.
3. The process according to claim 1 wherein the complexing agent is used in
an amount of 0.005 to 1 mol/l.
4. The process according to claim 2 or 3 wherein the second complexing
agent is used in an amount of 0.05 to 1.0 mol/l.
5. The process according to claim 4 wherein the second complexing agent is
used in an amount of 0.2 to 0.5 mol/l.
6. The process according to claim 5 wherein the second complexing agent is
selected from the group consisting of gluconic acid, lactic acid, acetic acid
and tartaric acid and salts thereof.
7. The process of claim 1 wherein the composition is obtained from a kit-of-
parts, said kit-of-parts comprising composition (A) and (B) wherein compo-
sition (A) comprises:
(A1) said iminosuccinic acid or a derivative thereof,
(A2) said soluble metal salt
and wherein composition (B) comprises:
(B1) said group IA metal hydroxide.
8. A composition for use in a process for applying a metal coating to a non-
conductive substrate comprising
(i) a Cu(ll), Ag, Au or Ni soluble metal salt or mixtures thereof,
(ii) iminosuccinic acid or a derivative thereof.
9. The composition according to claim 8 further comprising 0.05 to 5 mol/l of
a group IA metal hydroxide.
10. The composition according to claim 8 or 9 wherein the iminosuccinic acid
derivative has the formula (I):

wherein R1 is selected from the group consisting of H, Na, K, NH4, Ca, Mg,
Li and Fe,
R2 is selected from the group consisting of

-CH2-COOR1, -CH2-CH2-COOR1, -CH2-CH2-OH, -CH2-CHOH-CH3 and
-CH2-CHOH-CH2OH, and
R3 is selected from the group consisting of H, -CH2-COOR1,
-CH2-CH2-COOR1, -CH2-CH2-OH, -CH2-CHOH-CH3 and
-CH2-CHOH-CH2OH.
11. The composition according to claims 8 to 10 further comprising a second
complexing agent selected from the group consisting of acetate, acetylace-
tone, citric acid, 1,2-diaminocyclohexane-N,N,N',N'-tetraacetic acid, di-
methylglyoxime (50% dioxane), 2,2'-dipyridyl, ethanolamine, ethylenedia-
mine, ethylenediamine N.N.N'.N'-tetraacetic acid, glycine, N'-(2-
hydroxyethyl)ethylenediamine-N,N,N'-triacetic acid, 8-hydroxy-2-methyl-
quinoline (50% dioxane), 8-hydroxyquinoline-5-sulfonic acid, lactic acid, ni-
trilotriacetic acid, 1 -nitroso-2-naphthol (75% dioxane), oxalate, 1,10-
phenanthroline, phthalic acid, piperidine, propylene-1,2-diamine, pyridine,
pyridine-2,6-dicarboxyiic acid, 1-(2-pyridylazo)-2-naphthol (PAN), 4-(2-
pyridylazo)resorcinal (PAR), pyrocatechol-3,5-disulfonate, 8-quinolinoi,
salicyciic acid, succinic acid, 5-sulfosalicyclic acid, tartaric acid, thioglycolic
acid, thiourea, triethanolamine, triethylenetetramine (trien), 1,1,1-trifluoro-
3-2'-thenoylacetone (TTA) in an amount of 0.05 to 1.0 mol/l.
12. The composition according to claim 11 comprising the further complexing
agent in an amount of 0.2 to 0.5 mol/l.
13. The composition according to claim 12 wherein the further complexing
agent is selected from the group consisting of gluconic acid, lactic acid,
acetic acid and tartaric acid and salts thereof.

Described is a new process for applying a metal coating to a non-conductive substrate comprising the steps of (a)
contacting the substrate with an activator comprising a noble metal/group TVA metal sol to obtain a treated substrate, (b) contacting
said treated substrate with a composition comprising a solution of: (i) a Cu(II), Ag, Au or Ni soluble metal salt or mixtures thereof,
(ii) 0.05 to 5 mol/1 of a group IA metal hydroxide and (iii) a complexing agent for an ion of the metal of said metal salt, wherein an
iminosuccinic acid or a derivative thereof is used as said complexing agent.

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Patent Number

269607

Indian Patent Application Number

3506/KOLNP/2009

PG Journal Number

44/2015

Publication Date

30-Oct-2015

Grant Date

29-Oct-2015

Date of Filing

08-Oct-2009

Name of Patentee

ATOTECH DEUTSCHLAND GMBH

Applicant Address

ERASMUSSTRASSE 20, 10553 BERLIN GERMANY

Inventors:

#	Inventor's Name	Inventor's Address
1	DYRBUSCH, BRIGITTE	HARTMANNSTRASSE 22, 12207 BERLIN GERMANY
2	SCHADOW, SIGRID	NUTHESTRASSE 34, 14513 TELTOW GERMANY
3	FELS, CARL, CHRISTIAN	HABERSAATHSTRASSE 27, 10115 BERLIN GERMANY

PCT International Classification Number

C25D5/54; C23C18/28; C23C18/30

PCT International Application Number

PCT/EP2008/003345

PCT International Filing date

2008-04-24

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1	07008950.3	2007-05-03	EUROPEAN UNION