USE OF AN AQUEOUS ALKALINE COMPOSITION FOR THE ELECTROLESS DEPOSITION OF A METAL OR METAL ALLOY ON A METAL SURFACE OF A SUBSTRATE

Abstract

An aqueous alkaline deposition composition for the electroless deposition or metal or metal alloy on a metal surface, the composition comprising: (a) functionalized urea derivatives and/or salts thereof selected from the group comprising compounds having formula I and/or salts thereof:

##STR00001## wherein X is selected as oxygen; R.sup.1 and R.sup.2 are independently selected as nitrogen-comprising heteroaromatic compounds; wherein R.sup.1 and R.sup.2 can be identical or different; m is an integer from 1 to 6; and n is an integer from 1 to 6; wherein m and n can be identical or different; (b) one source of metal ions to be deposited onto the metal surface of the substrate wherein the deposited metal or metal alloy is different from the metal or metal alloy of the metal surface; and (c) optionally one source of alloying metal ions; and a method for the electroless deposition.

Claims

1. A method of electroless deposition of a metal or metal alloy on a metal surface of a substrate, comprising immersion of the substrate into an aqueous alkaline deposition composition comprising: (a) functionalized urea derivatives and/or salts thereof selected from the group comprising compounds having formula I and/or salts thereof: ##STR00004## wherein X is selected as oxygen; R.sup.1 and R.sup.2 are independently selected as nitrogen-comprising heteroaromatic compounds; wherein R.sup.1 and R.sup.2 can be identical or different; m is an integer from 2 to 6; and n is an integer from 2 to 6; wherein m and n can be identical or different; (b) at least one source of metal ions providing metal ions to be deposited as metal onto the metal surface of the substrate wherein the deposited metal or metal alloy is different from the metal or metal alloy of the metal surface; (c) optionally at least one source of alloying metal ions; and wherein the compounds having formula I and/or salts thereof are present in the composition at a total concentration from 1 wt.-% to 20 wt.-% based on the total weight of the composition.

2. The method according to claim 1 wherein the at least one source of metal ions is selected from a group consisting of (ii) a metal anode material which is in contact with the aqueous alkaline deposition composition, wherein said metal anode material is oxidized by applying an electric current to said anode, to enable an anodic oxidation method, resulting in a release of metal ions into the aqueous alkaline deposition composition; and (iii) a solid metal piece which is in contact with the aqueous alkaline deposition composition, wherein said solid metal piece is oxidized by an oxidizing agent dissolved the aqueous alkaline deposition composition, to enable an oxidation process, resulting in a release of metal ions into the aqueous alkaline deposition composition.

3. The method according to claim 1, wherein R.sup.1 and R.sup.2 is selected as substituted and/or unsubstituted imidazole, optionally comprising at least one substituent selected as C.sub.1-C.sub.6 alkyl.

4. The method according to claim 1, wherein n is an integer from 2 to 3 and/or m is an integer from 2 to 3.

5. The method according to claim 1, wherein the aqueous alkaline deposition composition has a pH value from 7.1 to 13.

6. The method according to claim 1, wherein the functionalized urea derivatives and/or salts thereof are selected as compounds having formula I and/or salts thereof, wherein m is 3, wherein n is 3, wherein R.sup.1 is imidazole, optionally comprising at least one substituent selected as C.sub.1-C.sub.6 alkyl; and wherein R.sup.2 is imidazole, optionally comprising at least one substituent selected as C.sub.1-C.sub.6 alkyl.

7. The method according to claim 1, wherein the compounds having formula I and/or salts thereof are present in the composition at a total concentration from 2 wt.-% to 15 wt.-%.

8. The method according to claim 2, wherein the oxidizing agent for oxidizing the solid metal piece of the aqueous alkaline deposition composition comprises oxygen dissolved in the aqueous alkaline deposition composition.

9. The method according to claim 1, wherein the at least one source of metal ions providing metal ions is selected from the group consisting of manganese, silver, copper, cobalt, and nickel.

10. The method according to claim 1, wherein the at least one source of metal ions providing metal ions is present in the composition at a total concentration from 0.1 wt.-% to 15 wt.-% based on the total weight of the composition.

11. The method according to claim 1 wherein the composition does not comprise a reducing agent and/or an anionic agent.

12. A method for the electroless deposition of a metal or metal alloy on a metal surface of a metal substrate, the method comprising the steps: (A) providing an aqueous alkaline deposition composition for the electroless deposition of a metal or metal alloy on a metal surface of a metal substrate according to claim 1, and (B) contacting the substrate with said aqueous alkaline deposition composition such that the metal or metal alloy is deposited on the metal surface of the metal substrate in an electroless way.

13. The method according to claim 12 wherein the substrates to be treated comprise metals or metal alloys selected from the group consisting of aluminum, copper, nickel, cobalt, manganese, zinc, lead, antimony, tin, rare earth metals, copper-zinc alloy, copper-tin alloy, copper-nickel alloy, and aluminum-magnesium alloy.

14. The method according to claim 12 wherein the metal ions to be deposited are selected from the group consisting of silver ions, nickel ions, manganese ions, cobalt ions and copper ions.

15. The method according to claim 12, wherein the method comprises the further step: (C) recycling the aqueous alkaline deposition composition after method step (B), wherein step (C) comprises the steps: (C1) Optionally increasing the temperature of the aqueous alkaline deposition composition to obtain a temperature-increased aqueous alkaline deposition composition, (C2) Filtering the aqueous alkaline deposition composition or the optionally temperature-increased aqueous alkaline deposition composition to obtain a filtered aqueous alkaline deposition composition; and (C3) Adding a source of metal ions and reapplying the filtered aqueous alkaline deposition composition to method step (A).

16. The method according to claim 1, wherein the composition comprises (c) at least one source of alloying metal ions.

17. The method according to claim 3, wherein the R1 or the R2 or both the R1 and the R2 are substituted imidazole comprising at least one substituent selected as C1-C6 alkyl.

18. The method according to claim 6, wherein the R1 or the R2 or both the R1 and the R2 are substituted imidazole comprising at least one substituent selected as C1-C6 alkyl.

19. The method according to claim 15, wherein step (C) comprises the steps: (C1) Increasing the temperature of the aqueous alkaline deposition composition to obtain a temperature-increased aqueous alkaline deposition composition, and (C2) Filtering the temperature-increased aqueous alkaline deposition composition to obtain a filtered aqueous alkaline deposition composition.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0072] In the context of the present invention, the term at least one or one or more denotes (and is exchangeable with) one, two, three or more than three.

[0073] The term C.sub.x-C.sub.y according to the present invention refers to a substance comprising a total number from X carbon atoms to Y carbon atoms. For example, the term C.sub.1-C.sub.6 alkyl refers to alkyl compounds comprising a total number from 1 carbon atom to 6 carbon atoms.

[0074] The present invention according to the first aspect provides a use of an aqueous alkaline deposition composition for the electroless deposition of a metal or metal alloy on a metal surface of a substrate, the composition comprising: [0075] (a) functionalized urea derivatives and/or salts thereof selected from the group comprising compounds having formula I and/or salts thereof:

##STR00003## [0076] wherein [0077] X is selected as oxygen; [0078] R.sup.1 and R.sup.2 are independently selected as nitrogen-comprising heteroaromatic compounds; [0079] wherein R.sup.1 and R.sup.2 can be identical or different; [0080] m is an integer from 2 to 6, more preferred 2 or 3; and [0081] n is an integer from 2 to 6, more preferred 2 or 3; [0082] wherein m and n can be identical or different; [0083] (b) at least one source of metal ions providing metal ions to be deposited as metal onto the metal surface of the substrate wherein the deposited metal or metal alloy is different to the metal or metal alloy of the metal surface; and [0084] (c) optionally at least one source of alloying metal ions; and wherein the compounds having formula I and/or salts thereof are present in the composition at a total concentration from 1 wt.-% to 20 wt.-% based on the total weight of the composition.

[0085] It is clear to the skilled person that at least one source of alloying metal ions is needed if a metal alloy shall be deposited on the metal surface of a substrate, instead of a single metal. Those alloying metals are preferred which have similar electrochemical potentials if complexed by compound (a) of the present invention and which are different to the metal of the metal surface to be treated.

[0086] According to the first and/or second aspect R.sup.1 and R.sup.2 are independently selected as nitrogen-comprising heteroaromatic compounds, wherein said nitrogen-comprising heteroaromatic compounds are preferably 4- to 10-membered heteroaromatic compounds comprising from 1 to 4 nitrogen atoms.

[0087] One advantage, which is achieved by the use of the aqueous alkaline deposition composition according to the first and/or second aspect of the present invention, results in an efficient deposition, for a variety of metals and/or metal alloys, in particular silver, nickel, manganese, cobalt, or copper, in particular resulting in a homogenous metal deposit. If one of these metals is used as the source of metal ions, two or more of the remaining sources can be used as alloying metal ions.

[0088] By using said aqueous alkaline deposition composition according to the first and/or second aspect of the present invention an effective roughness of the obtained metal deposits can be achieved, which allows for an efficient adhesion of any additional layer deposited on the metal deposit.

[0089] In particular, the used aqueous alkaline deposition composition can be regenerated so that the material consumption is limited, and a cost-effective and environmentally friendly process can be ensured.

[0090] Moreover, due to the nitrogen functionalities present in the functionalized urea derivatives having formula I, a highly efficient stabilization of metal ions in the composition can be achieved by chelating of said metal ions, which results in a reduced precipitation tendency of said metal ions.

[0091] In the following, advantageous embodiments of the deposition composition to be used according to the present invention will be explained in more detail.

[0092] According to the inventive use, the deposition composition is an aqueous alkaline deposition composition, which preferably comprises more than 50 vol.-% water, based on the total volume of the aqueous alkaline deposition composition, more preferably comprises 75 vol.-% or more water, even more preferably comprises 85 vol.-% or more water, even more preferably comprises 90 vol.-% or more water, even more preferably comprises 95 vol.-% or more water, and most preferably comprises 99 vol.-% or more water. Preferably, water is the only solvent in the aqueous alkaline deposition composition.

[0093] Preferably, the oxidizing agent for oxidizing the at least one metal for the deposition composition, which is present preferably in a solution in a separate tank to provide metal ions to be deposited, comprises oxygen dissolved in said solution.

[0094] Preferably the oxygen dissolved in the solution originates from atmospheric oxygen diffusing from the ambient air into the solution.

[0095] An aqueous alkaline deposition composition is preferred, wherein at least one of R.sup.1 and R.sup.2 is selected as substituted and/or unsubstituted 4- to 10-membered heteroaromatic compounds, optionally comprising from 1 to 4 nitrogen atoms, optionally comprising at least one substituent selected from the group comprising OR.sup.6 and C.sub.1-C.sub.4 alkyl, wherein R.sup.6 is selected from the group comprising hydrogen and C.sub.1-C.sub.3 alkyl; [0096] wherein preferably at least one of R.sup.1 and R.sup.2 is selected as substituted and/or unsubstituted 4- to 8-membered heteroaromatic compounds comprising from 1 to 3 nitrogen atoms, optionally comprising at least one substituent selected from the group comprising OR.sup.6 and C.sub.1-C.sub.3 alkyl, wherein R.sup.6 is selected from the group comprising hydrogen and C.sub.1- or C.sub.2 alkyl; [0097] wherein more preferably at least one of R.sup.1 and R.sup.2 is selected as substituted and/or unsubstituted 5- to 6-membered heteroaromatic compounds comprising from 1 to 2 nitrogen atoms, optionally comprising at least one substituent selected from the group comprising OR.sup.6 and C.sub.1-C.sub.6 alkyl, wherein R.sup.6 is selected from the group comprising hydrogen and C.sub.1-C.sub.6 alkyl; [0098] wherein even more preferably at least one of R.sup.1 and R.sup.2 is selected as substituted and/or unsubstituted imidazole, optionally comprising at least one substituent selected as C.sub.1-C.sub.6 alkyl; and wherein most preferably both of R.sup.1 and R.sup.2 are selected as unsubstituted imidazole.

[0099] An aqueous alkaline deposition composition is preferred, wherein both of R.sup.1 and R.sup.2 is selected as substituted and/or unsubstituted 4- to 10-membered heteroaromatic compounds, optionally comprising from 1 to 4 nitrogen atoms, optionally comprising at least one substituent selected from the group comprising OR.sup.6 and C.sub.1-C.sub.4 alkyl, wherein R.sup.6 is selected from the group comprising hydrogen and C.sub.1-C.sub.3 alkyl; [0100] wherein preferably both of R.sup.1 and R.sup.2 is selected as substituted and/or unsubstituted 4- to 8-membered heteroaromatic compounds comprising from 1 to 3 nitrogen atoms, optionally comprising at least one substituent selected from the group comprising OR.sup.6 and C.sub.1-C.sub.3 alkyl, wherein R.sup.6 is selected from the group comprising hydrogen and C.sub.1- or C.sub.2 alkyl; [0101] wherein more preferably both of R.sup.1 and R.sup.2 is selected as substituted and/or unsubstituted 5- to 6-membered heteroaromatic compounds comprising from 1 to 2 nitrogen atoms, optionally comprising at least one substituent selected from the group comprising OR.sup.6 and C.sub.1-C.sub.6 alkyl, wherein R.sup.6 is selected from the group comprising hydrogen and C.sub.1-C.sub.6 alkyl; [0102] wherein even more preferably both of R.sup.1 and R.sup.2 is selected as substituted and/or unsubstituted imidazole, optionally comprising at least one substituent selected as C.sub.1-C.sub.6 alkyl; and wherein most preferably both of R.sup.1 and R.sup.2 are selected as unsubstituted imidazole.

[0103] An aqueous alkaline deposition composition is preferred, wherein n is an integer from 2 to 3.

[0104] An aqueous alkaline deposition composition is preferred, wherein m is an integer from 2 to 3.

[0105] An aqueous alkaline deposition composition is preferred, wherein the functionalized urea derivatives and/or salts thereof are selected as compounds having formula I and/or salts thereof, wherein m is 3, wherein n is 3, [0106] wherein R.sup.1 is selected as substituted and/or unsubstituted 4- to 10-membered heteroaromatic compounds, preferably 5- to 6-membered heteroaromatic compounds, more preferably imidazole, optionally comprising at least one substituent selected as C.sub.1-C.sub.6 alkyl; [0107] and wherein R.sup.2 is selected as substituted and/or unsubstituted 4- to 10-membered heteroaromatic compounds, preferably 5- to 6-membered heteroaromatic compounds, more preferably imidazole, optionally comprising at least one substituent selected as C.sub.1-C.sub.6 alkyl.

[0108] An aqueous alkaline deposition composition is preferred, wherein for the compounds having formula I and/or salts thereof, X is selected as oxygen, m and n are both selected as 3, and R.sup.1 and R.sup.2 are both selected as imidazole, preferably unsubstituted imidazole.

[0109] An aqueous alkaline deposition composition is preferred, wherein the compounds having formula I and/or salts thereof are present in the composition preferably at a total concentration from 2 wt.-% to 15 wt.-%, more preferably from 5 wt.-% to 15 wt.-%, even more preferably from 7 wt.-% to 15 wt.-%, and most preferably from 10 wt.-% to 15 wt.-%.

[0110] By selecting the concentration of the compounds having formula I of compound (a) in the preferred concentration ranges an efficient deposition process can be ensured.

[0111] An aqueous alkaline deposition composition is preferred, wherein the composition does not comprise any additional oxidizing agent, wherein preferably the composition does not comprise any peroxide and/or persulfate compound. A use of an aqueous alkaline deposition composition according to the second aspect of the present invention is preferred, wherein the at least source of metal ions comprises at least one metal salt, for example copper chloride. Therefore, due to the addition of the metal salt no oxidation of any elemental metal in the deposition composition is necessary.

[0112] A use of an aqueous alkaline deposition composition according to the second aspect of the present invention is preferred, wherein the at least one source of metal ions is derived from a metal anode material, which is in contact with the aqueous alkaline deposition composition, wherein said metal anode material is oxidized by applying an electric current to said anode, to enable an anodic oxidation process. Therefore, due to the anodic oxidation no addition of any metal salt or oxidizing agent to the deposition composition is necessary. Preferably the deposition composition comprises an anionic agent as carboxylic acids and/or alkyl sulfonic acids and their salts.

[0113] In a preferred embodiment of the invention, the source of metal ions is a nickel anode which is dissolved within the deposition composition by applying an electrical current to obtain nickel ions. Preferable in this embodiment the deposition composition comprises citric acid. The current can be applied continuously or semi-continuously. The aqueous deposition composition is an aqueous alkaline deposition composition. In the context of the present invention, the term alkaline denotes alkaline, i.e. having a pH above 7. The pH is preferably ranging from 7.1 to 13. An aqueous alkaline deposition composition of the present invention is preferred, wherein the aqueous alkaline deposition composition comprises a pH from 8 to 13, preferably from 9 to 12, more preferably from 9 to 11, and most preferably from 9.5 to 10.5.

[0114] By selecting the pH in the preferred ranges an efficient deposition process can be ensured.

[0115] An aqueous alkaline deposition composition is preferred, wherein the at least one metal, which is to be deposited onto the metal surface, is selected from the group consisting of manganese, silver, copper, cobalt, or nickel. In case, the at least one metal is selected from the group consisting of manganese, copper, cobalt, or nickel, the metal of the metal surface to be treated cannot be manganese, copper, cobalt, or nickel at the same time, because the metal of the metal surface must be less noble than the metal to be deposited.

[0116] An aqueous alkaline deposition composition according to the second aspect is preferred, wherein the at least one metal source comprises manganese, silver, copper, cobalt, or nickel, in particular in ionic form, if the at least one metal source comprises a metal salt or if the at least one metal source is released into the deposition composition by anodic oxidation.

[0117] An aqueous alkaline deposition composition is preferred, wherein the at least one metal is present in the composition at a total concentration from 0.1 wt.-% to 15 wt.-% based on the total weight of the composition, preferably at a total concentration from 1 wt.-% to 12 wt.-%, more preferably from 0.75 wt.-% to 5 wt.-%, even more preferably from 1 wt.-% to 3 wt.-%, and most preferably from 1 wt.-% to 2 wt.-%.

[0118] In respect to the use of the aqueous alkaline deposition composition according to the second aspect, the above concentrations within the deposition composition also apply to the at least one metal derived from the at least one metal source either by adding the salt into the deposition composition or by releasing the corresponding metal ions into the deposition composition by anodic oxidation.

[0119] A use of an aqueous alkaline deposition composition of the present invention is preferred, wherein the substrate is a metal substrate wherein the metal provides the metal surface to be treated or substrate comprising a metal surface, which more preferably comprises metals or metal alloys selected from the group comprising copper, nickel, aluminum, cobalt, manganese, zinc, lead, antimony, tin, rare earth metals, for example neodymium, copper-zinc alloy, copper-tin alloy, copper-nickel alloy, and aluminum-magnesium alloy.

[0120] A use of an aqueous alkaline deposition composition of the present invention is preferred, wherein the substrate comprises copper, nickel, aluminum, zinc, or zinc coated steel.

[0121] An aqueous alkaline deposition composition is preferred, wherein the composition does not comprise an anionic agent. It could be found by own experiments that the addition of an acid, as hydrochloric acid, sulfuric acid, bromic acid, carboxylic acids as mono-, di- or tricarboxylic acid, e.g. acetic acid or citric acid, alkyl sulfonic acid as methane sulfonic acid, methane-disulfonic acid, methane-trisulfonic acid, aryl sulfonic acid as tosylate compounds, and metal salts thereof have a deteriorate effect of the deposition. It was observed that the addition of an anionic agent will prevent or defer the release of the metal ions to be deposited from functionalized urea derivativesmetal ion complex.

[0122] According to a third aspect the present invention is further directed to a method for the electroless deposition of a metal or metal alloy on a metal surface of a metal substrate, the method comprising the steps: [0123] (A) providing an aqueous alkaline deposition composition for the electroless deposition of a metal or metal alloy on a metal surface of a metal substrate according to the first aspect, and [0124] (B) contacting the substrate with said aqueous alkaline deposition composition such that the metal or metal alloy is deposited on the metal surface of the metal substrate in an electroless way.

[0125] According to a fourth aspect the present invention is further directed to a method for the electroless deposition of a metal or metal alloy on a metal surface of a substrate, the method comprising the steps: [0126] (A) providing an aqueous alkaline deposition composition for the electroless deposition of a metal or metal alloy on a metal surface of a substrate according to the second aspect, and [0127] (B) contacting the substrate with said aqueous alkaline deposition composition such that the metal or metal alloy is deposited on the metal surface of the substrate in an electroless way.

[0128] The method according to the third and fourth aspect ensures an efficient deposition process.

[0129] A method of the present invention is preferred, wherein the method is performed at a temperature from 20 C. to 100 C., preferably from 30 C. to 80 C., more preferably from 40 C. to 70 C., or 40 C. to 60 C., most preferably at 50 C. to 60 C., or at 50 C.

[0130] By performing the method at the preferred temperature ranges, a highly efficient deposition reaction can be ensured.

[0131] A method of the present invention is preferred, wherein the substrates to be treated comprise metal substrates, wherein preferably the metal substrates or substrates comprising metal surfaces comprise all metals and metal alloys used for immersion deposition (e.g. silicon, titanium, tantalum and zirconium therefore are excluded) which are less noble than gold and less noble than the metal to be deposited according to their electrochemical standard potential (measured against hydrogen by known methods), preferably with the exception of iron, chromium, and nickel-chromium steel alloys.

[0132] A method of the present invention is preferred, wherein the substrates to be treated comprise metals or metal alloys selected from the group consisting of aluminum, copper, nickel, cobalt, manganese, zinc, lead, antimony, tin, rare earth metals, for example neodymium, copper-zinc alloy, copper-tin alloy, copper-nickel alloy, and aluminum-magnesium alloy.

[0133] A method of the present invention is preferred, wherein the metal or metal surfaces of the substrates to be treated comprise copper, nickel, zinc, aluminum, zinc-coated steel and/or cobalt.

[0134] Thereby, the deposition efficiency of the method is adjusted to allow for an efficient deposition of a huge variety of metal substrates.

[0135] In some cases, a method of the present invention is particularly preferred, wherein the substrate and the metal surface thereof comprise, preferably are, aluminum or an aluminum alloy. This is most preferred if the metal and metal alloy, respectively, for electroless deposition comprises, preferably is, nickel, manganese, copper, and/or alloys thereof.

[0136] A method of the present invention is preferred, wherein during method step (B) no voltage is applied to the substrate. This means that no electrical current is involved as electron donor for reducing metal ions to the metal or metal alloy upon electroless deposition.

[0137] Furthermore, a method of the present invention is preferred, wherein the aqueous alkaline deposition composition is substantially free of, preferably does not comprise, a reducing agent for the electroless deposition of the metal and metal alloy, respectively, most preferably if the metal and metal alloy, respectively, is or comprises nickel and/or manganese. This preferably also applies generally to the aqueous alkaline deposition composition of the present invention. Thus, a conventional, e.g. chemical compound for reducing the metal and metal alloy, respectively, is preferably not needed.

[0138] Instead, a method of the present invention is most preferred, wherein the electroless deposition is an immersion deposition. This means that said deposition comprises a redox reaction involving said metal or metal alloy (preferably the metals or metal alloys as defined throughout the present text, more preferably nickel, manganese, and respective alloys thereof) and the surface of the substrate (preferably aluminum or aluminum alloy). In other words, the immersion deposition includes an electron transfer between at least two metals, meaning an electron transfer from a less noble metal to a more noble metal. more noble metal means view of the electrochemical series in this context that the redox potential of the complex of metal ions to be deposited and the functionalized urea derivatives is more noble than the metal of the metal surface, e.g. manganese ions complexed by the inventive functionalized urea derivatives are found to be more noble than the metallic zinc substrate. In the context of the present invention, the substrate (including its surface) and its metal surface thereof, is not considered as a reducing agent, but is part of the redox reaction between metal of metal surface and metal ions to be plated. Typically, such type of metal deposition is called immersion deposition. Also typically, such a metal deposition is preferably self-limiting because the more metal or metal alloy is deposited and thereby covering the substrate surface, the less access is provided to the surface metal to drive the process forward.

[0139] Thus, preferred is a method of the present invention, wherein the metal and metal alloy for deposition is different from the substrate, more specially from the metal or metal surface of the substrate.

[0140] During the use of the deposition composition to deposit metal on the metal surface, the concentration of the metal ions of the metal surface of the substrate rises in the deposition composition while the concentration of the metal ions derived from the source of metal ions declines. The accumulates metal ions derived from the metal surface of the substrate (or metal substrate) build precipitates and sink to the button of the depositing tank.

[0141] A method of the present invention is therefore preferred, wherein the method comprises the further step: [0142] (C) recycling the aqueous alkaline deposition composition after method step (B), wherein step (C) comprises the steps: [0143] (C1) Optionally, increasing the temperature of the aqueous alkaline deposition composition to obtain a temperature-increased aqueous alkaline deposition composition, [0144] (C2) Filtering the aqueous alkaline deposition composition or the optionally temperature-increased aqueous alkaline deposition composition to obtain a filtered aqueous alkaline deposition composition; and [0145] (C3) Adding a source of metal ions and reapplying the filtered aqueous alkaline deposition composition to method step (A).

[0146] The occurring precipitate can be removed from the solution by filtration or other comparable methods.

[0147] Additionally the decrease in metal concentration in the deposition composition due to the deposition of metal on the surface of the substrate can be counterbalanced by adding more metal source into the deposition composition, for example by adding elemental metal (solid metal pieces) in case of the method according to the third aspect, or for example by addition metal salt or by applying anodic oxidation in case of the method according to the fourth aspect.

[0148] A method of the present invention is preferred, wherein precipitates formed in the aqueous alkaline deposition composition during optionally method step (C1) are removed from the aqueous alkaline deposition composition during method step (C2) to obtain a precipitate-reduced filtered aqueous alkaline deposition composition after method step (C2). The increased temperature promotes the building of the precipitates.

[0149] If temperature is optionally increased, a method of the present invention is preferred, wherein the method is performed at a temperature from 20 C. to 100 C., preferably from 30 C. to 80 C., more preferably from 40 C. to 70 C. or 40 C. to 60 C., even more preferably at 50 C. to 60 C., most preferably at 50 C.

[0150] By removing the precipitates from the aqueous alkaline deposition composition, the metal ions, which have been removed from the treated metal surface, can be efficiently recovered.

[0151] By adding a source of metal ions according to method step (C3) the aqueous alkaline deposition composition can be replenished with metal ions to be deposited. The replenished and filtered aqueous alkaline deposition composition is than reapplied to method step (A).

[0152] A method of the present invention is preferred, wherein the metal substrate provided during step (A) is formed as a flexible metal substrate, preferably as a flexible copper substrate, more preferably as a flexible copper-coated polymer.

[0153] In some other cases, a flexible foil is preferred, most preferably an aluminum foil. This is most preferred, if the metal and metal alloy, respectively, for electroless deposition is or comprises nickel.

[0154] A method of the present invention is preferred, wherein the substrate provided during step (A) is formed as a copper-coated laminate or resin, or a uniform copper substrate.

[0155] By depositing metal or metal alloys on different kind of substrates with different chemical and physical properties the method can be applied in a wide scope of applications and is therefore generally usable.

[0156] For example, for printed circuit boards (PCBs) a copper-coated resin, in particular polymer, can be used or a copper-coated glass can be used as substrates. Alternatively, for general manufacturing goods, copper-coated plastics or copper-coated sheet metal can be used as substrates.

[0157] A method of the present invention is preferred, wherein step (A) and/or (B) is performed under stirring, preferably at a stirring rate from 20 rpm to 1.000 rpm, more preferably from 50 rpm to 500 rpm, and most preferably at 100 rpm.

[0158] A method of the present invention is preferred, wherein step (B) is performed for a duration less than 2 hours, preferably less than 1 hour, more preferably less than 45 min, even more preferably less than 30 min, and most preferably less than 15 min.

[0159] A method of the present invention is preferred, wherein step (B) is performed for a duration from 1 min to 2 hours, preferably from 5 min to 1.5 hours, more preferably from 15 min to 1 hour and most preferably from 50 min to 15 min.

[0160] The preferred stirring and time intervals of the method allow for an efficient deposition, which can be individually adjusted according to the used metal substrate.

[0161] A method of the present invention is preferred, wherein the method comprises a step (P), which is performed prior to step (B), wherein step (P) comprises: [0162] (P1) pre-rinsing the substrate with an acidic solution, preferably comprising sulfuric acid to obtain a pre-rinsed substrate, [0163] (P2) washing the pre-rinsed substrate with a wash solution, preferably comprising desalted water, to obtain a washed substrate, and [0164] wherein the washed substrate is contacted with said aqueous alkaline deposition composition during step (B).

[0165] By pre-rinsing the substrate with the acidic solution and a subsequent washing step, an efficient cleaning of the surface on which the metal is deposited during step (B) can be ensured, thereby increasing the effectivity of the method. By pre-rinsing the substrate any potential corrosion of the substrate and/or surface contaminations of the substrate can be efficiently removed before transferring the substrate into the aqueous alkaline deposition composition.

[0166] However, method step (P) is an optional method step, and the method according to the third and/or fourth aspect the present invention can be also performed without method step (P).

[0167] Preferably, the aforementioned regarding the aqueous alkaline deposition composition according to the first and second aspect of the present invention, preferably what is described as being preferred, applies likewise to the method according to the third and fourth aspect of the present invention.

[0168] In a very preferred specific aspect, the method of the present invention refers to an electroless immersion nickel deposition (i.e. without an individual reducing agent), wherein the aqueous alkaline deposition composition comprises nickel ions for electroless depositing nickel or a nickel alloy on aluminum or an aluminum alloy.

[0169] Preferably, in this specific aspect, the method of the present invention does not include a pre-treatment of the aluminum and aluminum alloy, respectively, with a pre-treatment composition comprising fluoride prior to step (B), [0170] or does only include a single treatment step of the aluminum and aluminum alloy, respectively, with a pre-treatment composition comprising fluoride prior to step (B). Most preferably, no pre-treatment with fluoride is carried out.

[0171] Preferably, in this specific aspect, the method of the present invention does not include a pre-treatment of the aluminum and aluminum alloy, respectively, with a pre-treatment composition comprising zinc prior to step (B), [0172] or does only include a single treatment step of the aluminum and aluminum alloy, respectively, with a pre-treatment composition comprising zinc prior to step (B). Most preferably, no pre-treatment with zinc is carried out.

[0173] Own experiments have shown that this specific aspect allows a significant reduction in pre-treatment effort compared to common plating on aluminum/aluminum alloy procedures. In many cases, an otherwise typical pre-treatment including more than one contacting with a pre-treatment composition comprising fluoride and/or zinc, typically known as zincate-pre-treatment, can be avoided. Rather, the compounds of formula I and salts thereof allow not only for an effective stabilization of the nickel ions in the aqueous alkaline deposition composition but also provide a pre-treatment effect on the aluminum/aluminum alloy surface by at least partly dissolving the detrimental passivation layer thereon.

[0174] Preferably, in this specific aspect, the method of the present invention does not include a pre-treatment of the aluminum and aluminum alloy, respectively, with a pre-treatment composition comprising nitric acid prior to step (B).

[0175] In this specific aspect, a method of the present invention is preferred, wherein in step (B) the deposited nickel or nickel alloy has a layer thickness ranging from 4 nm to 100 nm, preferably from 7 nm to 80 nm, more preferably from 10 nm to 60 nm, even more preferably from 15 nm to 40 nm, most preferably from 20 nm to 30 nm.

[0176] In this specific aspect, a method of the present invention is preferred, wherein step (B) is carried out for a time ranging from 1 minutes to 120 minutes, preferably from 1.5 minutes to 100 minutes, more preferably from 2 minutes to 80 minutes even more preferably from 2.5 minutes to 70 minutes, most preferably from 5 minutes to 15 minutes.

[0177] In this specific aspect, preferred is a method of the present invention comprising after step (B), step [0178] (B-1) contacting the substrate obtained in step (B) directly or in a subsequent step with a plating composition comprising nickel ions and a reducing agent for nickel or nickel alloy deposition.

[0179] Thus, in step (B-1) a further nickel or nickel alloy is electroless deposited on the nickel and nickel alloy, respectively, deposited by immersion deposition in step (B).

[0180] As a result, in steps (B) and (B-1) two consecutive nickel layers are deposited on each other.

[0181] Preferably, the aforementioned regarding the first and second aspect of the present invention applies likewise to the aforementioned specific aspect.

[0182] Preferably, the nickel and nickel alloy to be electroless deposited are either from nickel ions or metallic nickel as nickel source, most preferably from metallic nickel. Since compounds (a) dissolve metallic nickel such that nickel ions are formed, no additional counterion are added to the aqueous alkaline deposition composition. This is of great benefit.

[0183] According to a fifth aspect the present invention is further directed to a metal substrate with a deposited metal or metal alloy layer on the surface of the substrate, wherein the deposited metal or metal alloy layer has been obtained by a method for the electroless deposition of a metal or metal alloy on a surface of a substrate according to the third of fourth aspect.

[0184] Preferably, the aforementioned regarding the use of the aqueous alkaline deposition composition according to the first and second aspect of the present invention and the method according to the third and fourth aspect of the present invention, preferably what is described as being preferred, applies likewise to the substrate according to the fifth aspect of the present invention.

EXAMPLES

1. Silver Deposition on Surfaces of Substrates

Preparation of the Aqueous Alkaline Silver Deposition Composition 25.00 g (0.232 mol) of silver powder and a magnetic stir bar were placed in a 2000 ml beaker. Then 200.00 g (0.724 mol) of 1,3-bis(3-(1H-imidazol-1yl)propyl)urea was added and was dissolved in 1775 ml of deionized water. Stirring was carried out for 5 hours at 50 C. at a speed of 150 rpm. At the end of the reaction time, the liquid portion had turned blue-violet. Small amounts of undissolved silver powder were still at the bottom of the beaker. Water, which was evaporated during the 5 hours reaction time, was replenished with deionized water. The obtained yield is 2000.00 g (100.00%). After preparation, the aqueous alkaline silver deposition composition has a pH between 9 and 11 and is ready for the electroless deposition of silver on surfaces of substrates.

Electroless Deposition of Silver on a Surface of a Copper-Plated ABS Substrate

[0185] 2000 g of the aqueous alkaline silver deposition composition as prepared above was heated to 50 C. in a 2000 ml beaker for 20 minutes at a stirring rate of 150 rpm. The aqueous alkaline silver deposition composition was then transferred to a 2000 ml graduated cylinder with a magnetic stir bar. The copper-plated ABS substrate was immersed in 5% sulfuric acid for 10 seconds, then rinsed with plenty of deionized water and immediately coated by immersing the copper-plated ABS substrate in the aqueous alkaline silver deposition composition at 50 C. for 15 minutes. The composition was stirred at about 150 rpm during coating. After coating, the copper-plated ABS substrate was rinsed clear with deionized water and dried with compressed air. XRF analysis determined the silver layer thickness as 0.084 m.

Electroless Deposition of Silver on a Surface of a Copper Sheet

[0186] 2000 g of the aqueous alkaline silver deposition composition as prepared above was heated to 50 C. in a 2000 ml beaker for 20 minutes at a stirring rate of 150 rpm. The copper sheet was immersed in 5% sulfuric acid for 10 seconds, then rinsed with plenty of deionized water and immediately coated by immersing the copper sheet in the aqueous alkaline silver deposition composition at 50 C. for 15 minutes. The composition was stirred at about 150 rpm during coating. After coating, the copper sheet was rinsed clear with deionized water and dried with compressed air. XRF analysis determined the silver layer thickness as 0.089 m. The silver surface did not tarnish over time. After 12 weeks no tarnishing could be found. Also fingerprints did not remain on the surface or could be wiped away easily.

Electroless Deposition of Silver on a Surface of a Brass Sheet

[0187] 2000 g of the aqueous alkaline silver deposition composition as prepared above was heated to 50 C. in a 2000 ml beaker for 20 minutes at a stirring rate of 150 rpm. The brass sheet was immersed in 5% sulfuric acid for 10 seconds, then rinsed with plenty of deionized water and immediately coated by immersing the brass sheet in the aqueous alkaline silver deposition composition at 50 C. for 15 minutes. The composition was stirred at about 150 rpm during coating. After coating, the brass sheet was rinsed clear with deionized water and dried with compressed air. XRF analysis determined the silver layer thickness as 0.128 m.

Electroless Deposition of Silver on a Surface of a Copper-Plated FR4 Panel

[0188] 2000 g of the aqueous alkaline silver deposition composition as prepared above was heated to 50 C. in a 2000 ml beaker for 20 minutes at a stirring rate of 150 rpm. The copper-plated FR4 panel was immersed in 5% sulfuric acid for 10 seconds, then rinsed with a lot of deionized water and coated immediately by immersing the copper-plated FR4 panel in the aqueous alkaline silver deposition composition at 50 C. for 15 minutes. The composition was stirred at about 150 rpm during coating. After coating, the copper-plated FR4 panel was rinsed clear with deionized water and dried with compressed air. XRF analysis determined the silver layer thickness as 0.775 m.

Electroless Deposition of Silver on a Surface of a Copper-Plated HMP Panel

[0189] 2000 g of the aqueous alkaline silver deposition composition as prepared above was heated to 50 C. in a 2000 ml beaker for 20 minutes at a stirring rate of 150 rpm. The copper-plated HMP panel was immersed in 5% sulfuric acid for 10 seconds, then rinsed with plenty of deionized water and immediately coated by immersing the copper-plated HMP panel in the aqueous alkaline silver deposition composition for 15 minutes at 50 C. with an immersion depth of 25%, for another 15 minutes with an immersion depth of 50% and for another 15 minutes at 50 C. with an immersion depth of 75%. The composition was stirred at about 150 rpm during coating. After coating, the copper-plated HMP panel was rinsed clear with deionized water and dried with compressed air. XRF analysis determined the silver layer thicknesses after 15 minutes as 0.087 m, after 30 minutes as 0.141 m and after 45 minutes as 0.178 m.

Electroless Long-Term Deposition of Silver on a Surface of a Copper-Plated HMP Panel

[0190] 2000 g of the aqueous alkaline silver deposition composition as prepared above was heated to 50 C. in a 2000 ml beaker for 20 minutes at a stirring rate of 150 rpm. The copper-plated HMP panel was immersed in 5% sulfuric acid for 10 seconds, then rinsed with a lot of deionized water and immediately coated by immersing the copper-plated HMP panel in the aqueous alkaline silver deposition at 50 C. for 20 hours at an immersion depth of 75%. The composition was stirred at about 150 rpm during coating. After coating, the copper-plated HMP panel was rinsed clear with deionized water and dried with compressed air. XRF analysis determined the silver layer thickness as 0.428 m.

Electroless Deposition of Silver on a Surface of a Copper-Plated Glass Panel

[0191] 2000 g of the aqueous alkaline silver deposition composition as prepared above was heated to 50 C. in a 2000 ml beaker for 20 minutes at a stirring rate of 150 rpm. The copper-plated glass panel was immersed in 5% sulfuric acid for 10 seconds, then rinsed with plenty of deionized water and immediately coated by immersing the copper-plated glass panel in the aqueous alkaline silver deposition composition at 50 C. for 5 minutes. The composition was stirred at about 150 rpm during coating. After coating, the copper-plated glass panel was rinsed clear with deionized water and dried with compressed air. XRF analysis determined the silver layer thickness as 0.059 m.

Electroless Deposition of Silver on a Surface of a Copper-Plated Piece of a Wafer

[0192] 2000 g of the aqueous alkaline silver deposition composition as prepared above was heated to 50 C. in a 2000 ml beaker for 20 minutes at a stirring rate of 150 rpm. A copper-plated piece of a wafer was immersed in 5% sulfuric acid for 10 seconds, then rinsed with a lot of deionized water and immediately coated by immersing the copper-plated piece of the wafer in the aqueous alkaline silver deposition composition at 50 C. for 5 minutes. The immersion depth was 95%. The composition was stirred at approximately 150 rpm during coating. After coating, the wafer piece was rinsed clear with deionized water and dried with compressed air. XRF analysis determined the silver layer thickness as 0.137 m.

Electroless Deposition of Silver on a Surface of a High-Frequency Aluminum Socket

[0193] 2000 g of the aqueous alkaline silver deposition composition as prepared above was heated to 50 C. in a 2000 ml beaker for 20 minutes at a stirring rate of 150 rpm. The high-frequency aluminum socket was immersed in 5% sulfuric acid for 15 seconds until an area-wide gas evolution started. The high-frequency aluminum socket was then rinsed with plenty of deionized water and immediately coated by immersing the high-frequency aluminum socket in the aqueous alkaline silver deposition composition for 5 minutes at 50 C., while the composition was stirred at approximately 150 rpm during coating. After coating, the high-frequency aluminum socket was rinsed clear with deionized water and dried with compressed air. XRF analysis determined the silver layer thickness as 0.085 m.

Electroless Deposition of Silver on a Surface of a High-Frequency Aluminum Socket

[0194] 2000 g of the aqueous alkaline silver deposition composition as prepared above was heated to 50 C. in a 2000 ml beaker for 20 minutes at a stirring rate of 150 rpm. The high-frequency aluminum socket was immersed in 5% sulfuric acid for 15 seconds until an area-wide gas evolution started. The high-frequency aluminum socket was then rinsed with plenty of deionized water and immediately coated by immersing the high-frequency aluminum socket in the aqueous alkaline silver deposition composition for 15 minutes at 50 C., while the composition was stirred at approximately 150 rpm. After coating, the high-frequency aluminum socket was rinsed clear with deionized water and dried with compressed air. XRF analysis determined the silver layer thickness as 0.352 m.

[0195] The aqueous alkaline silver deposition composition as prepared above deposits translucent to opaque, matte to shiny silver layers on a variety of different substrates as used above, which do no longer tarnish over time. Silver deposit layers of 0.05 m to 0.75 m are obtained at temperatures between 30 C. to 50 C. after a coating time from 5 minutes to 60 minutes.

Use and Recycling of the Aqueous Alkaline Silver Deposition Composition

[0196] During the use of the deposition composition the concentration of the metal ions of the metal surface of the substrate (as explained in the example above) rises in the deposition composition while the concentration of the available silver ions derived from the source of silver ions declines.

[0197] For recycling of the deposition composition or parts thereof, the deposition composition was filtered to separate precipitates of the metal ions derived from the metal surface. The filtered aqueous alkaline deposition composition was replenished by adding silver powder in principle as described under preparation of the aqueous alkaline silver deposition composition above. In consequence, the silver powder is dissolved and thus provides the silver ions. The silver ions will be complexed by the compound as mentioned above. Finally, the replenished and filtered aqueous alkaline deposition composition will be used again in method step (A).

2. Nickel Deposition on a Surface of a Substrate

Preparation of the Aqueous Alkaline Nickel Deposition Composition

[0198] 25.00 g (0.426 mol) of nickel anode spheres (diameter approximately 8 mm) and a small magnetic stir bar were carefully placed at the bottom of a 2000 ml beaker. Then 200.00 g (0.724 mol) of 1,3-bis(3-(1H-imidazol-1yl)propyl)urea was added and was dissolved in 1775 ml of deionized water. The composition was stirred for 168 hours at 50 C., at a speed of 150 rpm such that the nickel anode spheres are not moved. At the end of the reaction time, the composition had turned blue-green. Small amounts of undissolved nickel anode spheres were still at the bottom of the beaker. Water, which was evaporated during the 168 hours reaction time, was replenished with deionized water. The obtained yield was 2000.00 g (100.00%). After preparation, the aqueous alkaline nickel deposition composition has a pH between 9 and 11 and is ready for the electroless deposition of nickel on a surface of a substrate.

Electroless Deposition of Nickel on a Zinc Surface of a Galvanized Steel Sheet

[0199] 2000 g of the aqueous alkaline nickel deposition composition as prepared above were heated to 40 C. in a 2000 ml beaker for 60 minutes at a stirring rate of 150 rpm. The zinc galvanized steel sheet was immersed in 5% sulfuric acid for 15 seconds until an area-wide gas evolution started. The zinc galvanized steel sheet was then rinsed with plenty of deionized water and immediately coated by immersing the zinc galvanized steel sheet in the aqueous alkaline nickel deposition composition at 40 C. for 60 minutes. The composition was stirred at approximately 150 rpm during coating. After coating, the zinc galvanized steel sheet was rinsed clear with deionized water and dried with compressed air. XRF analysis determined the nickel layer thickness as 0.018 m.

Electroless Deposition of Nickel on a Zinc Surface of a Galvanized Steel Sheet

[0200] 2000 g of the aqueous alkaline nickel deposition composition as prepared above were heated to 60 C. in a 2000 ml beaker for 50 minutes at a stirring rate of 150 rpm. The zinc galvanized steel sheet was immersed in 5% sulfuric acid for 15 seconds until an area-wide gas evolution started. The zinc galvanized steel sheet was then rinsed with plenty of deionized water and immediately coated by immersing the zinc galvanized steel sheet in the aqueous alkaline nickel deposition composition at 60 C. for 60 minutes. The composition was stirred at approximately 150 rpm during coating. After coating, the zinc galvanized steel sheet was rinsed clear with deionized water and dried with compressed air. XRF analysis determined the nickel layer thickness as 0.029 m.

Electroless Deposition of Nickel on a Surface of an Aluminum Connector

[0201] 1000 g of the aqueous alkaline nickel deposition composition as prepared above were heated to 60 C. in a 2000 ml beaker for 38 minutes at a stirring rate of 150 rpm. The aluminum connector was directly coated, by immersing the aluminum connector in the aqueous alkaline nickel deposition composition at 60 C. for 15 minutes. The composition was stirred at approximately 150 rpm during coating. After coating, the aluminum connector was rinsed clear with deionized water and dried with compressed air. FIB analysis determined the nickel layer thickness as 0.013 m.

Electroless Deposition of Nickel on a Surface of an Aluminum Connector

[0202] Electroless deposition of nickel on a surface of an aluminum connector, followed by a chemical deposition (i.e. with the help of a reducing agent) of nickel on a surface of an aluminum connector.

[0203] 1000 g of the aqueous alkaline nickel deposition composition as prepared above were heated to 60 C. in a 2000 ml beaker for 38 minutes at a stirring rate of 150 rpm. The aluminum connector was directly coated, by immersing the aluminum connector in the aqueous alkaline nickel deposition composition at 60 C. for 15 minutes. The composition was stirred at approximately 150 rpm during coating. After coating, the aluminum connector was rinsed clear with deionized water and dried with compressed air.

[0204] 500 g of an aqueous chemical nickel deposition composition (Nichem MP 1188 available by Atotech Deutschland GmbH) were heated to 88 C. in a 1000 ml beaker for 44 minutes at a stirring rate of 150 rpm. The nickel immersion coated aluminum connector was directly coated, by coating the nickel immersion coated aluminum connector in the aqueous chemical nickel deposition composition at 88 C. for 20 minutes. The composition was not stirred during coating. After coating, the nickel immersion and chemical nickel coated aluminum connector was rinsed clear with deionized water and dried with compressed air. FIB analysis determined the immersion nickel layer thickness as 0.016 m.

Comparative ExampleElectroless Deposition of Nickel on a Surface of an Aluminum Connector

[0205] In a 1000 ml beaker with magnetic stirring bar, 250 ml deionized water was added, then with vigorous stirring, first 5.50 g nickel(II)sulfate and then 15.00 g ammonium chloride were added. The light green solution was stirred at approximately 150 rpm. The light green solution was mixed with deionized water to a volume of 500 ml and heated to 60 C. for 37 minutes. The aluminum connector was directly coated, by immersing the aluminum connector in the aqueous chemical nickel deposition composition at 60 C. for minutes. The composition was stirred at approximately 150 rpm during coating. After coating, the aluminum connector was rinsed clear with deionized water and dried with compressed air. FIB analysis determined the nickel layer thickness as 0.032 m. The obtained Ni immersion layer shows poor homogeneity and defects.

[0206] The aqueous alkaline nickel deposition composition deposits translucent to opaque, matte to bright nickel layers on aluminum, zinc, and tin substrates. Depending on the surface properties of the base material, these can be matte to highly polished. Nickel deposit layers of 0.02 m to 0.03 m are obtained in 60 minutes, at temperatures from 40 C. to 60 C., which do no longer tarnish over time.

Use and Recycling of the Aqueous Alkaline Nickel Deposition Composition

[0207] During the use of the deposition composition the concentration of the metal ions of the metal surface of the substrate (as explained in the example above) rises in the deposition composition while the concentration of the available nickel ions derived from the source of nickel ions declines.

[0208] For recycling of the deposition composition or parts thereof, the deposition composition was filtered to separate precipitates of the metal ions derived from the metal surface. The filtered aqueous alkaline deposition composition was replenished by adding nickel powder in principle as described under preparation of the aqueous alkaline nickel deposition composition above. In consequence, the nickel powder is dissolved and thus provides the nickel ions. The nickel ions will be complexed by the compound as mentioned above.

[0209] Finally, the replenished and filtered aqueous alkaline deposition composition will be used again in method step (A).

3. Manganese Deposition on a Surface of a Substrate

Preparation of the Aqueous Alkaline Manganese Deposition Composition

[0210] 25.00 g (0.455 mol) of manganese pieces and a small magnetic stir bar were carefully placed on the bottom of a 2000 ml beaker. Then 200.00 g (0.724 mol) of 1,3-bis(3-(1H-imidazol-1yl)propyl)urea was added and was dissolved in 1775 ml of deionized water. Stirring was carried out for 60 hours at 30 C. at a speed of 150 rpm. It was prevented that the temperature of the composition rises above 40 C., to avoid an uncontrollable autocatalytic reaction, in which the manganese would dissolve exothermically with strong hydrogen evolution. At the end of the stirring, the liquid composition had turned light blue. Small amounts of undissolved manganese pieces were still at the bottom of the beaker. Water, which was evaporated during the 60 hours reaction time, was replenished with deionized water. The obtained yield was 2000.00 g (100.00%). After preparation, the aqueous alkaline manganese deposition composition has a pH between 9 and 11 and is ready for the electroless deposition of manganese on a surface of a substrate.

Electroless Deposition of Manganese on a Zinc Surface of a Galvanized Steel Sheet

[0211] 2000 g of the aqueous alkaline manganese deposition composition as prepared above were heated to 30 C. in a 2000 ml beaker for 35 minutes at a stirring rate of 150 rpm. A zinc galvanized steel sheet measuring 70120.2 mm was immersed in 5% sulfuric acid for 15 seconds until an area-wide gas evolution started. The zinc galvanized steel sheet was then removed, rinsed with plenty of deionized water and immediately coated by immersing the zinc galvanized steel sheet in the aqueous alkaline manganese deposition composition at 30 C. for 60 minutes. The composition was stirred at approximately 150 rpm during coating. After coating, the zinc galvanized steel sheet was rinsed clear with deionized water and dried with compressed air. XRF analysis determined the manganese layer thickness as 0.012 m.

Electroless Deposition of Manganese on a Zinc Surface of a Galvanized Steel Sheet

[0212] 2000 g of the aqueous alkaline manganese deposition composition as prepared above were heated to 30 C. for 18 minutes in a 2000 ml beaker at a stirring rate of 150 rpm. A zinc galvanized steel sheet measuring 7070 mm was immersed in 5% sulfuric acid for 10 seconds until gas evolution started over the entire area. The zinc galvanized steel sheet was then removed, rinsed with plenty of deionized water and immediately coated by immersing the zinc galvanized steel sheet in the aqueous alkaline manganese deposition composition at 30 C. for 90 minutes. The composition was stirred at approximately 150 rpm during coating. After coating, the zinc galvanized steel sheet was rinsed with deionized water and dried with compressed air. XRF analysis determined the manganese layer thickness as 0.111 m.

Electroless Deposition of Manganese on a Surface of an Aluminum Connector

[0213] 500 g of the aqueous alkaline manganese deposition composition as prepared above were heated to 30 C. in a 1000 ml beaker for 12 minutes at a stirring rate of 150 rpm. The aluminum connector was directly coated, by immersing the aluminum connector in the aqueous alkaline manganese deposition composition at 30 C. for 15 minutes. The composition was stirred at approximately 150 rpm during coating. After coating, the aluminum connector was rinsed clear with deionized water and dried with compressed air. FIB analysis determined the manganese layer thickness as 0.019 m.

Electroless Deposition of Manganese on a Surface of an Aluminum Connector, Followed by a Chemical Deposition of Nickel on a Surface of an Aluminum Connector

[0214] 500 g of the aqueous alkaline manganese deposition composition as prepared above were heated to 30 C. in a 1000 ml beaker for 12 minutes at a stirring rate of 150 rpm. The aluminum connector was directly coated, by immersing the aluminum connector in the aqueous alkaline manganese deposition composition at 30 C. for 15 minutes. The composition was stirred at approximately 150 rpm during coating. After coating, the aluminum connector was rinsed clear with deionized water and dried with compressed air.

[0215] 500 g of an aqueous chemical nickel deposition composition (Nichem MP 1188 available by Atotech Deutschland GmbH) were heated to 88 C. in a 1000 ml beaker for 44 minutes at a stirring rate of 150 rpm. The nickel immersion coated aluminum connector was directly coated, by coating the nickel immersion coated aluminum connector in the aqueous chemical nickel deposition composition at 88 C. for 20 minutes. The composition was not stirred during coating. After coating, the manganese immersion and chemical nickel coated aluminum connector was rinsed clear with deionized water and dried with compressed air. FIB analysis determined the nickel layer thickness as 0.015 m.

[0216] The aqueous alkaline manganese deposition composition deposits translucent to opaque, gray to pinkish manganese layers on aluminum and zinc, which become silver-colored when heated strongly. Depending on the surface condition of the aluminum or zinc surface, the deposit layers can be dull to highly polished. Manganese layers of 0.01 m are obtained at 30 C. in 60 minutes.

Use and Recycling of the Aqueous Alkaline Manganese Deposition Composition

[0217] During the use of the deposition composition the concentration of the metal ions of the metal surface of the substrate (as explained in the example above) rises in the deposition composition while the concentration of the available manganese ions derived from the source of manganese ions declines.

[0218] For recycling of the deposition composition or parts thereof, the deposition composition was filtered to separate precipitates of the metal ions derived from the metal surface. The filtered aqueous alkaline deposition composition was replenished by adding manganese powder in principle as described under preparation of the aqueous alkaline manganese deposition composition above. In consequence, the manganese powder is dissolved and thus provides the manganese ions. The manganese ions will be complexed by the compound as mentioned above. Finally, the replenished and filtered aqueous alkaline deposition composition will be used again in method step (A).

4. Cobalt Deposition on Surfaces of Substrates

Preparation of the Aqueous Alkaline Cobalt Deposition Composition

[0219] 10.10 g (0.170 mol) of cobalt powder and a magnetic stir bar were placed in a 1000 ml beaker. Then, 100.00 g (0.289 mol) of 1,3-bis(3-(1H-imidazol-1yl)propyl)urea (80% wt.-% dissolved in water) was added and was dissolved in 700 ml of deionized water. Stirring was carried out for 24 hours at 50 C. at a speed of 150 rpm. At the end of the reaction time, the composition had turned pink. Small amounts of undissolved cobalt powder were still at the bottom of the beaker. Water, which was evaporated during the 24 hours reaction time, was replenished with deionized water. The obtained yield was 810.10 g (100.00%). After preparation, the aqueous alkaline cobalt deposition composition has a pH between 9 and 11 and is ready for the electroless deposition of cobalt on surfaces of substrates.

Electroless Deposition of Cobalt on a Surface of Aluminum Perforated Plate

[0220] 2000 g of the aqueous alkaline cobalt deposition composition as prepared above was heated to 50 C. in a 2000 ml beaker at a stirring rate of 150 rpm in 36 minutes. The aluminum perforated plate was immersed in 5% sulfuric acid for 10 seconds, then rinsed with plenty of deionized water and was immediately coated by immersing the aluminum perforated plate in the aqueous alkaline cobalt deposition composition for 15 minutes at 50 C. with an immersion depth of 90%, for another 15 minutes with an immersion depth of 60% and for another 15 minutes with an immersion depth of 30%. The composition was stirred at about 150 rpm during coating. After coating, the aluminum perforated plate was rinsed clear with deionized water and dried with compressed air. XRF analysis determined the cobalt layer thicknesses as follows: a cobalt layer after 15 minutes was not detectable; a cobalt layer after 30 minutes has a thickness of 0.003 m and a cobalt layer after 45 minutes has a thickness of 0.011 m.

Electroless Deposition of Cobalt on a Zinc Surface of Galvanized Steel Sheet

[0221] 2000 g of the aqueous alkaline cobalt deposition composition as prepared above was heated to 50 C. for 39 minutes in a 2000 ml beaker at a stirring rate of 150 rpm. The zinc galvanized steel sheet was immersed in 5% sulfuric acid for 10 seconds, then rinsed with plenty of deionized water and immediately coated by immersing the zinc galvanized steel sheet in the aqueous alkaline cobalt deposition composition for 15 minutes at 50 C. with an immersion depth of 90%, for another 15 minutes with an immersion depth of 60% and for another 15 minutes with an immersion depth of 30%. The composition was stirred at about 150 rpm during coating. After coating, the zinc galvanized steel sheet was rinsed clear with deionized water and dried with compressed air. XRF analysis determined the cobalt layer thicknesses as follows: cobalt layer after 15 minutes: 0.017 m, cobalt layer after 30 minutes: 0.024 m and cobalt layer after 45 minutes: 0.028 m.

[0222] The aqueous alkaline cobalt deposition composition deposits translucent to opaque cobalt layers on aluminum and zinc, which no longer tarnish. The shiny layers shine in all spectral colors depending on the incidence of light. This effect persists even after six months of storage under atmospheric conditions. Depending on the surface condition of the aluminum or zinc surface, the cobalt deposit layers can be matte to highly glossy. Uniformly closed cobalt deposit layers of 0.003-0.028 m are obtained at 50 C. for 5 minutes to 60 minutes.

Use and Recycling of the Aqueous Alkaline Cobalt Deposition Composition

[0223] During the use of the deposition composition the concentration of the metal ions of the metal surface of the substrate (as explained in the example above) rises in the deposition composition while the concentration of the available cobalt ions derived from the source of cobalt ions declines.

[0224] For recycling of the deposition composition or parts thereof, the deposition composition was filtered to separate precipitates of the metal ions derived from the metal surface. The filtered aqueous alkaline deposition composition was replenished by adding cobalt powder in principle as described under preparation of the aqueous alkaline cobalt deposition composition above. In consequence, the cobalt powder is dissolved and thus provides the cobalt ions. The cobalt ions will be complexed by the compound as mentioned above. Finally, the replenished and filtered aqueous alkaline deposition composition will be used again in method step (A).

5. Copper Deposition on Surfaces of Substrates

Preparation of the Aqueous Alkaline Copper Deposition Composition

[0225] 26.411 g (0.416 mol) of copper foil pieces (approximately 11 cm) and a magnetic stir bar were placed in a 3000 ml beaker. Then, 211.29 g (0.765 mol) of 1,3-bis(3-(1H-imidazol-1yl)propyl)urea was added and was dissolved in 2139.31 ml of deionized water. Stirring was carried out for 60 hours at 50 C. at a speed of 150 rpm. At the end of the reaction time, the composition had turned bright blue. Small amounts of undissolved copper foil pieces were still at the bottom of the beaker. Water, which was evaporated during the 60 hours reaction time, was replenished with deionized water. The obtained yield was 2377.01 g (100.00%). After preparation, the aqueous alkaline copper deposition composition has a pH between 9 and 11 and is ready for the electroless deposition of copper on surfaces of substrates.

Electroless Deposition of Copper on a Surface of an Aluminum Perforated Plate

[0226] 2000 g of the aqueous alkaline copper deposition composition as prepared above was heated to 50 C. in a 2000 ml beaker at a stirring rate of 150 rpm for 39 minutes. The aluminum perforated plate was immersed in 5% sulfuric acid for 10 seconds, then rinsed with plenty of deionized water and immediately coated by immersing the aluminum perforated plate in the aqueous alkaline copper deposition composition for 15 minutes at 50 C. with an immersion depth of 90%, for another 15 minutes with an immersion depth of 60% and for another 15 minutes with an immersion depth of 30%. The composition was stirred at about 150 rpm during coating. After coating, the aluminum perforated plate was rinsed clear with deionized water and dried with compressed air. XRF analysis determined the copper layer thicknesses as follows: copper layer after 15 minutes: 0.004 m, copper layer after 30 minutes: 0.006 m and copper layer after 45 minutes: 0.007 m.

Electroless Deposition of Copper on a Surface of an Aluminum Foil

[0227] 2000 g of the aqueous alkaline copper deposition composition as prepared above was heated to 60 C. in a 2000 ml beaker at a stirring rate of 150 rpm in 38 minutes. The aluminum foil was immersed in 5% sulfuric acid for 10 seconds, then rinsed with plenty of deionized water and immediately coated by immersing the aluminum foil in the aqueous alkaline copper deposition composition for 15 minutes at 60 C. with an immersion depth of 90%, for another 15 minutes at an immersion depth of 60% and for another 15 minutes at an immersion depth of 30%. The composition was stirred at about 150 rpm during coating. After coating, the aluminum foil was rinsed clear with deionized water and dried with compressed air. XRF analysis determined the copper layer thicknesses as follows: copper layer after 15, 30 and 45 minutes: 0.007 m.

Electroless Deposition of Copper on a Surface of an Aluminum Connector

[0228] 500 g of the aqueous alkaline copper deposition composition as prepared above were heated to 50 C. in a 1000 ml beaker for 25 minutes at a stirring rate of 150 rpm. An aluminum connector measuring 30.729.5 mm was rinsed with deoinized water and immersed in 5.00% sulfuric acid for 60 seconds. After 20 seconds an area-wide gas evolution started. The aluminum connector was then removed, rinsed with plenty of deionized water and immediately coated by immersing the aluminum connector in the aqueous alkaline copper deposition composition at 50 C. for 15 minutes. The composition was stirred at approximately 150 rpm during coating. After coating, the aluminum connector was rinsed clear with deionized water and dried with compressed air. A homogenous Cu layer was obtained. A copper layer thickness of 16.97 m was determined by FIB analysis.

Electroless Deposition of Copper on an Aluminum Surface of an Aluminum Panel

[0229] 1000 g of the aqueous alkaline copper deposition composition as prepared above were heated to 50 C. in a 1000 ml beaker for 25 minutes at a stirring rate of 150 rpm. An aluminum panel measuring 12744.30.6 mm was rinsed with deionized water and immersed in 5.00% sulfuric acid for 60 seconds. After 20 seconds an area-wide gas evolution started. The aluminum panel was then removed, rinsed with plenty of deionized water and immediately coated by immersing the aluminum panel in the aqueous alkaline copper deposition composition at 50 C. for 15 minutes. The composition was stirred at approximately 150 rpm during coating. After coating, the aluminum panel was rinsed clear with deionized water and dried with compressed air. An inhomogeneous and porous Cu layer was obtained. A copper layer thickness of 121.92 m was determined by FIB analysis.

Electroless Deposition of Copper on a Zinc Surface of a Galvanized Steel Sheet

[0230] 2000 g of the aqueous alkaline copper deposition composition as prepared above was heated to 60 C. in a 2000 ml beaker for 35 minutes at a stirring rate of 150 rpm. The zinc galvanized steel sheet was immersed in 5% sulfuric acid for 10 seconds, then rinsed with plenty of deionized water and immediately coated by immersing the zinc galvanized steel sheet in the aqueous alkaline copper deposition composition for 15 minutes at 60 C. with an immersion depth of 90%, for another 15 minutes at an immersion depth of 60% and for another 15 minutes at an immersion depth of 30%. The composition was stirred at about 150 rpm during coating. After coating, the zinc galvanized steel sheet was rinsed clear with deionized water and dried with compressed air. XRF analysis determined the copper layer thicknesses as follows: copper layer after 15 minutes: 0.023 m, copper layer after 30 minutes: 0.037 m and copper layer after 45 minutes: 0.042 m.

Electroless Deposition of Copper on a Surface of an Aluminum Connector

[0231] 500 g of the aqueous alkaline copper deposition composition as prepared above were heated to 50 C. in a 1000 ml beaker for 26 minutes at a stirring rate of 150 rpm. The aluminum connector was directly coated, by immersing the aluminum connector in the aqueous alkaline copper deposition composition at 50 C. for 15 minutes. The composition was stirred at approximately 150 rpm during coating. After coating, the aluminum connector was rinsed clear with deionized water and dried with compressed air. FIB analysis determined the copper layer thickness as 0.017 m.

Electroless Deposition of Copper on a Surface of an Aluminum Connector, Followed by an Electrochemical Deposition of Copper on a Surface of an Aluminum Connector

[0232] 500 g of the aqueous alkaline copper deposition composition as prepared above were heated to 50 C. in a 1000 ml beaker for 26 minutes at a stirring rate of 150 rpm. The aluminum connector was directly coated, by immersing the aluminum connector in the aqueous alkaline copper deposition composition at 50 C. for 15 minutes. The composition was stirred at approximately 150 rpm during coating. After coating, the aluminum connector was rinsed clear with deionized water and dried with compressed air.

[0233] 500 g Cupracid UP600 (available by Atotech Deutschland GmbH) without brightener were added to the 1000 ml beaker under gentle stirring. A 50702 mm titanium grid was used as anode. The aluminum connector was attached to an aluminum wire and immersed for 20 minutes at 20 C. in an acidic copper bath at 3A/dm.sup.2. The distance between the aluminum connector and titanium grid was 4 cm. After plating, the immersion copper-coated and electrochemical copper plated connector was rinsed with deionized water and dried with compressed air. The obtained copper layer thickness was very homogeneous and closed.

[0234] The aqueous alkaline copper deposition composition deposits translucent to opaque copper layers on aluminum and zinc, which no longer tarnish. Depending on the surface condition of the aluminum or zinc surface, the copper layers can be matte to high-gloss. Uniformly closed layers 0.004-0.042 m at 50 C. to 75 C. can be obtained from 5 minutes to 60 minutes.

Use and Recycling of the Aqueous Alkaline Copper Deposition Composition

[0235] During the use of the deposition composition the concentration of the metal ions of the metal surface of the substrate (as explained in the example above) rises in the deposition composition while the concentration of the available copper ions derived from the source of copper ions declines.

[0236] For recycling of the deposition composition or parts thereof, the deposition composition was filtered to separate precipitates of the metal ions derived from the metal surface. The filtered aqueous alkaline deposition composition was replenished by adding copper powder in principle as described under preparation of the aqueous alkaline copper deposition composition above. In consequence, the copper powder is dissolved and thus provides the copper ions. The copper ions will be complexed by the compound as mentioned above. Finally, the replenished and filtered aqueous alkaline deposition composition will be used again in method step (A).