Use of an aqueous alkaline composition for electroless deposition of metals or metal alloys on metallic surfaces of substrates - Patents.com

Abstract

The present invention relates to the use of an aqueous alkaline deposition composition for electroless deposition of metals or metal alloys on metal surfaces, the composition comprising: (a) a compound represented by formula (I), wherein X is selected as oxygen and R 1 and R 2 are independently selected as nitrogen-containing heteroaromatic compounds, R 1 and R 2 may be the same or different, m is an integer from 1 to 6, n is an integer from 1 to 6, and m and n may be the same or different), and / or salts thereof; (b) a source of metal ions to be deposited onto the metal surface of a substrate, wherein the deposited metal or metal alloy is different from the metal or metal alloy of the metal surface; and (c) optionally a source of alloying metal ions. JPEG2024543641000005.jpg32170

Description

[Technical field]

[0001] The present invention relates according to a first and a second aspect to the use of an aqueous alkaline deposition composition for the electroless deposition of a metal or metal alloy, in particular silver, nickel, manganese, cobalt or copper, on a metallic surface of a substrate.

[0002] According to a third aspect, the present invention is further directed to a method for electroless deposition of a metal or metal alloy, in particular silver, nickel, manganese, cobalt, or copper, on a metallic surface of a metal substrate with an aqueous alkaline deposition composition according to the first aspect.

[0003] According to a fourth aspect, the present invention is further directed to a method for electroless deposition of a metal or metal alloy, in particular silver, nickel, manganese, cobalt, or copper, on a metal surface of a substrate with an aqueous alkaline deposition composition according to the second aspect.

[0004] According to a fifth aspect, the present invention is further directed to a substrate having a deposited metal or metal alloy layer, in particular a silver, nickel, manganese, cobalt or copper layer, on a metallic surface of the substrate, wherein the deposited metal or metal alloy layer has been obtained by a method for electroless deposition of a metal or metal alloy on a metallic surface of a substrate according to the third or fourth aspect. [Background technology]

[0005] Substrates, such as metal-based substrates, can be coated with various metals or metal alloys to achieve a metal coating layer on the surface of the respective substrate. Depending on the type of metal or metal alloy and the material of the substrate surface, various applications are possible.

[0006] For example, US 3,472,742 relates to plating nickel on aluminum castings. Disclosed is a method which involves treating the aluminum with a relatively hot electroless nickel plating solution to apply a flash plate of nickel to the aluminum.

[0007] US 3,666,529 relates to a method for conditioning an alumina surface to receive electroless nickel plating.

[0008] EP3360988A1 relates to pyridinium compounds containing a building block -[AD)- having a moiety (A) urea or biuret structure with at least one pyridinium residue and nitrogen-containing residues X1 and X2, the urea or biuret structure being linked to a moiety (D) ether or thioether group. The pyridinium compounds are suitable as plating additives for copper deposition.

[0009] Firstly, said metal coating can serve as a functional layer on the surface of the respective substrate, enabling effective protection of said substrate from, for example, aggressive gases or liquids, by means of a corrosion-resistant metal coating, the type of which is essentially determined by the intended use of the article.

[0010] Secondly, the metal coating can serve as a decorative layer on the surface of the respective substrate, enabling desired optical surface properties.

[0011] Third, the metallization can provide conductive structures on the surface of the respective substrate, allowing for example the creation of electrical circuit boards.

[0012] Exemplary metal coatings according to the present application include silver, nickel, manganese, copper, or cobalt coatings and can be applied to a variety of substrates, such as metal substrates.

[0013] In order to apply said metal or metal alloy coating to the respective substrate, the corresponding metal must be stabilized in the respective deposition composition in order to avoid agglomeration of the metal precipitate in the deposition composition. [Prior art documents] [Patent documents]

[0014] [Patent Document 1] US3,472,742 [Patent Document 2] US3,666,529 [Patent Document 3] EP3360988A1 Summary of the Invention [Problem to be solved by the invention]

[0015] It was therefore a first object of the present invention to provide a use of a deposition composition and a method for electroless deposition of a metal or metal alloy onto a metallic surface of a substrate, which allows an efficient metal deposition, in particular a metal deposition resulting in a homogeneous and closed metal coating layer on the metallic surface of the substrate. This preferably includes providing a simplified method, for example, in which fewer pretreatment steps are required or even pre-treatment steps in general are no longer required, resulting in a method sequence with a generally reduced number of steps.

[0016] It was therefore a second object of the present invention to provide a method and a use of a deposition composition for electroless deposition of metals or metal alloys on the metallic surface of a substrate, which can be applied using a wide variety of metals or metal alloys, for example silver, nickel, manganese, cobalt or copper.

[0017] It was therefore a third object of the present invention to provide a method and use of a deposition composition for electroless deposition of metals or metal alloys on metal surfaces of substrates, which can be used for electroless deposition on a number of different metal surfaces, such as copper, brass, aluminum, zinc, and / or steel surfaces as well as zinc-coated steel.

[0018] It was therefore a fourth object of the present invention to provide a method and a use of a deposition composition for the electroless deposition of metals or metal alloys on the metallic surfaces of a substrate, which can be used for electroless deposition on a number of different metallic substrates, for example on large area metallic surfaces in the technical field of general manufacturing on the one hand and on microstructures on printed circuit boards in the technical field of electronics on the other hand.

[0019] Therefore, a fifth object of the present invention was to provide a method and use of a deposition composition for electroless deposition of a metal or metal alloy on a metallic surface of a substrate, which allows for the regeneration of the deposition composition to enable an environmentally friendly and cost-effective process, which most preferably includes realizing a longer life and utilization time of the respective deposition composition within the respective process.

[0020] It was therefore a sixth object of the present invention to provide a method and use of a deposition composition for electroless deposition of a metal or metal alloy on a metallic surface of a substrate, in which the metal ions are effectively stabilized in the deposition composition to prevent precipitation.

[0021] It was therefore a seventh object of the present invention to provide a use of a deposition composition and a method for electroless deposition of a metal or metal alloy on a metallic surface of a substrate, in which an additional layer subsequently deposited on the deposited metallic coating has excellent functional and / or decorative qualities.

[0022] It was therefore an eighth object of the present invention to provide a method and use of a deposition composition for electroless deposition of a metal or metal alloy on a metallic surface of a substrate, comprising chemical compounds with reduced toxicity.

[0023] Finally, an object was to provide an improved electroless deposition composition and method for the electroless deposition of metals or metal alloys on metallic surfaces of substrates, such that the use of an electric current for deposition can be avoided. [Means for solving the problem]

[0024] The aforementioned objects are solved by the present invention, in particular by the first to fifth aspects.

[0025] According to a first aspect, there is provided a use of an aqueous alkaline deposition composition for the electroless deposition of a metal or metal alloy on a metallic surface of a substrate, the composition comprising: (a) Formula I:

[0026] [ka]

[0027] (In the formula, X is selected as oxygen; R 1 and R 2 are independently selected as the nitrogen-containing heteroaromatic compound; R 1 and R 2 may be the same or different, m is an integer from 2 to 6, preferably 2 or 3; n is an integer from 2 to 6, preferably 2 or 3; m and n may be the same or different) and / or a salt thereof, (b) at least one metal ion source providing metal ions to be deposited as a metal on the metal surface of the substrate, the metal or metal alloy being deposited being different from the metal or metal alloy of the metal surface; (c) optionally at least one source of alloying metal ions; and wherein the compound having formula I and / or its salt is present in the composition in a total concentration of 1 wt.-% to 20 wt.-% relative to the total mass of the composition.

[0028] Preferably, the aqueous alkaline precipitation composition has a pH of from 7.1 to 13.

[0029] The aqueous alkaline deposition composition used for electroless deposition of metals or metal alloys on the metal surface of a substrate allows efficient deposition of a wide variety of metals or metal alloys on a wide variety of substrate metal surfaces (see examples below). The "metal surface of a substrate" in the context of the present invention includes substrates made of metals or metal layers having a metallic surface (wherein the metal or metal layer provides the metallic surface to be treated). Substrates also include any other (non-metallic) material such as resins, glass, composites thereof, including metallic surfaces to be treated onto non-metallic substrates. Both substrates will be used interchangeably therein unless otherwise stated.

[0030] When "functionalized urea derivatives" is mentioned below, it always includes the meaning of "and / or salts thereof", unless otherwise stated.

[0031] Surprisingly, it has been found that the functionalized urea derivatives defined in (a) realize a remarkable ability to dissolve, complex and deposit a wide variety of metals or metal alloys on the surface of the wide variety of substrate metals. Most interestingly, these compounds simultaneously fulfill this role. It has been found that the compounds of (a) can be utilized very flexibly and therefore reversibly. In many cases, such as the metal surfaces of Zn, Al, Sn and Mn, the compounds of (a) slightly dissolve the very metal surface of such substrates. This means, on the one hand, that the metal surface of the substrate is freshly prepared for subsequent metallization, and thus the typical pretreatment step can be omitted.

[0032] Moreover, it has been observed that such dissolved metals form precipitates in the deposition composition that can be simply removed by filtration. This means that the compound of (a) has the ability to dissolve these metals without too strong complex formation with them. This in turn means that at the same time, the compound of (a) can directly load the metal ions to be deposited by metal salts, dissolve solid metal pieces of metal by oxidation, or dissolve metal anodic materials by applying an electric current to provide the respective source of ions to be deposited for metal deposition. Moreover, such loaded ions are surprisingly directly deposited onto the metal surface of the substrate or onto a freshly prepared metal surface of the substrate. Also surprisingly, deposition onto the metal surface does not require an electric current or a reducing agent to reduce the metal ions. This means that a pure metal layer can be deposited onto the metal surface. "Pure" in this context means that no alloying elements such as boron or nitrogen have been co-precipitated (as would normally occur by using a boron or nitrogen containing reducing agent), and "pure" in this context means a metal content of the deposited metal layer of at least 98 wt.-%, more preferably 99 wt.-%, and most preferably 99.9 wt.-%.

[0033] As a consequence of the foregoing, the aqueous alkaline deposition composition is used according to the present invention for the electroless deposition of metals or metal alloys, the electroless deposition being so-called immersion deposition, in which the aqueous alkaline deposition composition does not contain any intentionally added reducing agent (see further details herein below).

[0034] In the composition, the functionalized urea derivative forms a complex with the metal ion to be deposited. When the composition is used, for example, when it is contacted with the metal or metal surface of a metal substrate, the redox potential of the complex formed is more noble than that of the metal or metal surface of the metal substrate. For example, it can be found that manganese, which is normally more noble (redox potential of -1.03 V vs. hydrogen), can be shifted to a more noble potential by forming a complex with the functionalized urea derivative of the present invention. As a result, manganese can be deposited on the normally larger zinc surface (redox potential of -0.77 V vs. hydrogen).

[0035] Compound (a) is available again after depositing the loaded metal ions (derived from the metal ion source) and can therefore participate again in the cycle. Despite the inevitable scooping out of very small amounts of compound (a) and partial film deposition on the deposited metal, the total amount of compound (a) remains relatively stable. Since there is no current, no electrolytic decomposition or destruction is observed.

[0036] As mentioned, the above cycle is most preferably applied to Zn, Al, Sn and Mn substrates and can be carried out for a very long time. Further explanations and preferred features are described throughout this specification. However, when the substrate is a Cu substrate, compound (a) still dissolves the very metal surface of the substrate, but copper is more significantly complexed by compound (a) as in the case of Zn, Al, Sn and Mn substrates. As a result, compound (a) becomes saturated with copper ions after some time. The principles of the present invention are still applicable, but compound (a) must be released from the copper ions at least after some time. Therefore, the cycle is relatively shorter compared to Zn, Al, Sn and Mn substrates. However, independent experiments have shown that such release can also be obtained by simply applying a temperature increase for a relatively short time to form the respective copper precipitate, which can be filtered in a subsequent step (see examples below).

[0037] In particular, the use of the aqueous alkaline deposition composition allows for the efficient deposition of silver, nickel, manganese, cobalt, or copper. From the above definition of "at least one source of metal ions", it becomes clear that, for example, copper cannot be deposited if it is also the metal of the metal surface being treated.

[0038] Furthermore, the aqueous alkaline deposition composition allows homogeneous deposition of the metal or metal alloy on the metal surface of the substrate during the deposition process, thus minimizing surface defects of the resulting metal coating. Such an efficient deposition process is particularly characterized by a constant deposition rate, which allows evenly distributed deposition of the metal or metal alloy on the substrate surface during the deposition process, thus resulting in a uniform and closed metal surface, which can be obtained after the deposition process. "Closed" in this context means that the resulting metal surface does not exhibit deposition errors, such as holes.

[0039] Furthermore, without being bound by theory, the aqueous alkaline deposition composition appears to achieve an effective roughness of the treated metal surface onto which the metal or metal alloy layer is deposited, which in turn improves the adhesion of the deposited layer as well as the adhesion of any additional layers subsequently deposited on the deposited metal coating. Such effective roughness of the treated metal surface can apparently be transferred to the additionally deposited layers, which also result in increased roughness, optimizing the functional and / or decorative properties of the resulting surface.

[0040] Furthermore, the deposited metal surfaces show good tarnish resistance properties. It has been found through independent experiments that the resulting metal surfaces do not tarnish over time, especially in the case of silver deposition, and furthermore, fingerprints do not remain on the surface or can be easily wiped off. Without being bound by theory, it appears that the compound (a) used in the aqueous alkaline deposition composition remains as a film on the resulting surface and reduces the improved tarnish resistance effect. Own experiments show tarnish resistance protection of, for example, deposited silver surfaces for several months up to one year. The deposited thin film of compound (a) also shows a positive effect on corrosion resistance.

[0041] Furthermore, the aqueous alkaline deposition composition can be applied for electroless deposition on a variety of different substrates, especially substrates with metal surfaces, such as foils, sheets, screws, bolts and the like, or larger metal surface areas on plastic parts in the general metal finishing technology field; or smaller metal surface areas, such as panels, foils, printed circuit boards (PCBs) or metal structures, such as conductive lines and vias, in the electronics technology field. Substrates that can be used with the present invention are substrates selected from the group consisting of, for example, copper-coated laminates or resins; copper-plated FR4 panels or HMP panels; PCBs or ABS resins with copper surfaces; glass panels or silicon wafers with at least one copper surface to be treated; sheets or foils made of copper, brass, zinc-coated steel parts; copper or copper-plated panels; connector or socket substrates, such as aluminum or copper sockets / connectors; and hinges and rims made of aluminum.

[0042] Furthermore, the functionalized urea derivatives and / or salts thereof selected from the group comprising the compounds having formula I of the aqueous alkaline deposition composition may allow an efficient stabilization, in particular by chelation (complexation), of the metal ions present in the deposition composition, thus minimizing the tendency of said metal ions to precipitate.

[0043] In particular, since the functionalized urea derivatives according to the present invention are capable of forming chelates of the resulting metal ions, thereby stabilizing the metal ions, the aqueous alkaline deposition composition does not require the addition of further stabilizing agents, and preferably the aqueous alkaline deposition composition does not explicitly comprise a stabilizing agent for stabilizing the metal ions in the deposition composition.

[0044] Furthermore, the compounds of formula I have low toxicity compared to other precipitating compounds previously used in the prior art.

[0045] An additional particular advantage of the aqueous alkaline precipitation compositions according to the invention is the possibility to regenerate the compounds of said compositions in order to enable an environmentally friendly and cost-effective process.

[0046] The first to eighth objects above are achieved by the present invention. The aqueous alkaline deposition composition preferably comprises: (i) at least one metal salt; (ii) a metallic anodic material in contact with the aqueous alkaline deposition composition, which is oxidized by applying an electric current to said anode to enable an anodization process, resulting in the release of metal ions into the aqueous alkaline deposition composition; (iii) a solid metal piece in contact with the aqueous alkaline deposition composition, the solid metal piece being oxidized by an oxidizing agent dissolved in the aqueous alkaline deposition composition to enable an oxidation process, resulting in the release of metal ions into the aqueous alkaline deposition composition; Preferably, at least one metal ion source is used, selected from the group consisting of:

[0047] Alternative (iii) is preferably provided in a separate tank, directly providing a solution of the complexes (a), (b) and optionally (c), with the oxidizing agent preferably being completely consumed. This solution is then added to the aqueous alkaline deposition composition to be used. This makes it possible to avoid the presence of an oxidizing agent in the aqueous alkaline deposition composition. The oxidizing agent, preferably only oxygen, is dissolved in the deposition composition and added to the deposition composition (e.g. by mixing and stirring the deposition composition) to allow only effective oxidation of the solid metal pieces in the deposition composition, thereby providing the metal ions to be plated in the deposition composition. More preferably, dissolved oxygen is the only oxidizing agent and no other oxidizing agents are added.

[0048] Preferably, the at least one source of metal ions is (i) at least one metal salt and / or (ii) a metal anodic material in contact with the aqueous alkaline deposition composition, which is oxidized by applying an electric current to said anode to enable an anodization process, resulting in the release of metal ions into the aqueous alkaline deposition composition. A more preferred source of at least one metal ion is (i) at least one metal salt.

[0049] In particular, the at least one metal ion source of the aqueous alkaline deposition composition according to the present invention can be applied directly to the deposition composition in ionic form, for example, by dissolving a metal salt directly in the deposition composition; therefore, oxidation of any elemental metal is not necessary.

[0050] Alternatively, or in addition, in particular, the at least one metal ion source of the aqueous alkaline deposition composition according to the invention may be derived from a metallic anodic material in contact with the aqueous alkaline deposition composition, which is oxidized by applying an electric current to said anode to enable an anodization process, resulting in the release of metal ions into the aqueous alkaline deposition composition, thus again not requiring oxidation of any elemental metal.

[0051] When the at least one metal ion source is selected from the group consisting of (i) and (ii), the composition does not include any additionally added oxidizing agent.

[0052] The object of the above is to provide a method for electroless deposition of a metal or metal alloy on a metallic surface of a metallic substrate, the metallic substrate providing said metallic surface to be treated, comprising: (A) providing an aqueous alkaline deposition composition for electroless deposition of a metal or metal alloy on a metal surface of a metal substrate according to a first aspect; (B) contacting a metal substrate with the aqueous alkaline deposition composition such that a metal or metal alloy is electrolessly deposited on the metal surface of the metal substrate; The problem is solved by a third aspect by a method comprising:

[0053] The object of the above is to provide a method for electroless deposition of a metal or metal alloy on a metallic surface of a substrate, comprising: (A) providing an aqueous alkaline deposition composition for electroless deposition of a metal or metal alloy on a metal surface of a substrate according to the second aspect; (B) contacting a substrate with the aqueous alkaline deposition composition such that a metal or metal alloy is electrolessly deposited on the metallic surface of the substrate; The problem is solved by a fourth aspect by a method, comprising:

[0054] The methods for electroless deposition according to the third and fourth aspects allow for excellent metal deposition on the treated substrate.

[0055] The above mentioned object is solved according to a fifth aspect by a substrate having a deposited metal or metal alloy layer on a metallic surface of the substrate, the deposited metal or metal alloy layer being obtained by a method for electroless deposition of a metal or metal alloy on a metallic surface of a substrate according to the third or fourth aspect. Said substrate, in particular a metallic substrate, comprises an effective metal deposit.

[0056] Surprisingly, it can be observed that during and after the deposition of metal from the deposited metal ions, the functionalized urea derivatives are partially coated as a thin film on the deposited metal surface. On the one hand, this film acts as a corrosion protection layer and a tarnish-resistant layer for, for example, silver deposits. On the other hand, the coated functionalized urea derivatives lose their complexing activity and redissolution of the deposited metal. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0057] In the context of the present invention, the terms "at least one" or "one or more" refer to (and are interchangeable with) "one, two, three or more than three".

[0058] C according to the present invention x ~C yThe term refers to a substance containing a total of X carbon atoms to Y carbon atoms. For example, the term C1-C6 alkyl refers to an alkyl compound containing a total of 1 carbon atom to 6 carbon atoms.

[0059] The present invention relates according to a first aspect to the use of an aqueous alkaline deposition composition for the electroless deposition of a metal or metal alloy on a metallic surface of a substrate, the composition comprising: (a) Formula I:

[0060] [ka] (I)

[0061] (In the formula, X is selected as oxygen; R 1 and R 2 are independently selected as the nitrogen-containing heteroaromatic compound; R 1 and R 2 may be the same or different, m is an integer from 2 to 6, more preferably 2 or 3; n is an integer from 2 to 6, more preferably 2 or 3; m and n may be the same or different) and / or a salt thereof, (b) at least one metal ion source that provides metal ions to be deposited as a metal on the metal surface of the substrate, the metal or metal alloy being deposited being different from the metal or metal alloy of the metal surface; (c) optionally at least one source of alloying metal ions; wherein the compound having formula I and / or a salt thereof is present in the composition in a total concentration of 1 wt.-% to 20 wt.-% relative to the total mass of the composition.

[0062] It will be clear to those skilled in the art that if, instead of a single metal, a metal alloy is deposited on the metal surface of the substrate, at least one source of alloying metal ions is required. Preferred is an alloying metal that has a similar electrochemical potential when complexed by the compound (a) of the present invention and is different from the metal of the metal surface to be treated.

[0063] According to the first and / or second aspect, R 1 and R 2 are independently selected as nitrogen-containing heteroaromatic compounds, and the nitrogen-containing heteroaromatic compounds are preferably 4- to 10-membered heteroaromatic compounds containing 1 to 4 nitrogen atoms.

[0064] One advantage achieved by the use of the aqueous alkaline deposition composition according to the first and / or second aspect of the present invention is that it provides efficient deposition, and in particular homogeneous metal deposits, for various metals and / or metal alloys, in particular silver, nickel, manganese, cobalt or copper. When one of these metals is used as a source of metal ions, two or more of the remaining sources can be used as alloying metal ions.

[0065] 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 deposit can be achieved, which allows efficient adhesion of any additional layers deposited on the metal deposit.

[0066] In particular, the used aqueous alkaline precipitation composition can be regenerated, thereby limiting material consumption and ensuring a cost-effective and environmentally friendly process.

[0067] Furthermore, due to the nitrogen functional groups present in the functionalized urea derivatives having formula I, a highly efficient stabilization of the metal ions in the composition can be achieved by chelation of said metal ions, which results in a reduction in the tendency of said metal ions to precipitate.

[0068] In the following, advantageous embodiments of the deposition compositions used according to the invention are explained in more detail.

[0069] According to the use of the present invention, the deposition composition is an aqueous alkaline deposition composition that preferably contains more than 50 vol.-% water, more preferably contains 75 vol.-% water or more, even more preferably contains 85 vol.-% water or more, even more preferably contains 90 vol.-% water or more, even more preferably contains 95 vol.-% water or more, and most preferably contains 99 vol.-% water or more, based on the total volume of the aqueous alkaline deposition composition. Preferably, water is the only solvent in the aqueous alkaline deposition composition.

[0070] Preferably, the oxidizing agent for oxidizing at least one metal for the deposition composition is preferably present in solution in a separate tank to provide the metal ions to be deposited and includes oxygen dissolved in said solution.

[0071] Preferably, the oxygen dissolved in the solution comes from atmospheric oxygen which diffuses into the solution from the surrounding air.

[0072] R 1 and R 2 At least one of the following is OR 6 and C1-C4 alkyl, optionally containing 1 to 4 nitrogen atoms, and optionally containing at least one substituent selected from the group consisting of substituted and / or unsubstituted 4- to 10-membered heteroaromatic compounds, 6 is selected from the group consisting of hydrogen and C1-C3 alkyl; Preferably R 1 and R 2 At least one of the following is OR 6 and C1-C3 alkyl, R 6 is selected from the group consisting of hydrogen and C1 alkyl or C2 alkyl; More preferably, R 1 and R2 At least one of the following is OR 6 and C1-C6 alkyl, R 6 is selected from the group consisting of hydrogen and C1-C6 alkyl; Even more preferably R 1 and R 2 at least one of which is selected as a substituted and / or unsubstituted imidazole optionally containing at least one substituent selected as a C1-C6 alkyl; Most preferably R 1 and R 2 are both selected as unsubstituted imidazoles; Aqueous alkaline deposition compositions are preferred.

[0073] R 1 and R 2 Both OR 6 and C1-C4 alkyl, optionally containing 1 to 4 nitrogen atoms, and optionally containing at least one substituent selected from the group consisting of substituted and / or unsubstituted 4- to 10-membered heteroaromatic compounds, 6 is selected from the group consisting of hydrogen and C1-C3 alkyl; Preferably R 1 and R 2 Both OR 6 and C1-C3 alkyl, R 6 is selected from the group consisting of hydrogen and C1 alkyl or C2 alkyl; More preferably, R 1 and R 2 Both OR 6 and C1-C6 alkyl, R 6is selected from the group consisting of hydrogen and C1-C6 alkyl; Even more preferably R 1 and R 2 are selected as substituted and / or unsubstituted imidazoles, optionally containing at least one substituent selected as C1-C6 alkyl; Most preferably R 1 and R 2 are both selected as unsubstituted imidazoles; Aqueous alkaline deposition compositions are preferred.

[0074] Aqueous alkaline deposition compositions in which n is an integer from 2 to 3 are preferred.

[0075] Aqueous alkaline deposition compositions in which m is an integer from 2 to 3 are preferred.

[0076] The functionalized urea derivative and / or salt thereof is selected as a compound having formula I and / or a salt thereof, wherein m is 3 and n is 3, R 1 is selected as a substituted and / or unsubstituted 4- to 10-membered heteroaromatic compound optionally containing at least one substituent selected as C1-C6 alkyl, preferably a 5- to 6-membered heteroaromatic compound, more preferably imidazole; R 2 is selected as a substituted and / or unsubstituted 4- to 10-membered heteroaromatic compound, optionally comprising at least one substituent selected as C1-C6 alkyl, preferably a 5- to 6-membered heteroaromatic compound, more preferably an imidazole.

[0077] 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 1 and R 2 are both selected as imidazoles, preferably unsubstituted imidazoles.

[0078] Preferred are aqueous alkaline precipitation compositions in which the compound having formula I and / or salts thereof are present in the composition in a total concentration of preferably from 2 wt.-% to 15 wt.-%, more preferably from 5 wt.-% to 15 wt.-%, even more preferably from 7 wt.-% to 15 wt.-%, most preferably from 10 wt.-% to 15 wt.-%.

[0079] By selecting the concentration of the compound having formula I of compound (a) within the preferred concentration range, an efficient precipitation process can be ensured.

[0080] Aqueous alkaline deposition compositions that do not contain any additional oxidizing agent, preferably do not contain any peroxide and / or persulfate compounds, are preferred. Aqueous alkaline deposition compositions according to the second aspect of the present invention are preferred, in which at least the source of metal ions comprises at least one metal salt, such as copper chloride. Thus, due to the addition of metal salts, oxidation of any elemental metal in the deposition composition is not necessary.

[0081] The use of the aqueous alkaline deposition composition according to the second aspect of the present invention is preferred, in which at least one source of metal ions is derived from a metal anodic material, which is in contact with the aqueous alkaline deposition composition, and said metal anodic material is oxidized by applying an electric current to said anode to enable the anodic oxidation process.Therefore, the addition of any metal salt or oxidizing agent to the deposition composition is not necessary for the anodic oxidation.Preferably, the deposition composition comprises an anionic agent such as carboxylic acid and / or alkylsulfonic acid and their salts.

[0082] In a preferred embodiment of the present invention, the metal ion source is a nickel anode that is dissolved in the deposition composition by applying an electric current to obtain nickel ions. A preferred deposition composition in this embodiment comprises citric acid. The electric 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 greater than 7. The pH is preferably in the range of 7.1 to 13. Aqueous alkaline deposition compositions of the present invention with a pH of 8 to 13, preferably 9 to 12, more preferably 9 to 11, most preferably 9.5 to 10.5 are preferred.

[0083] By selecting a pH within the preferred range, an efficient precipitation process can be ensured.

[0084] Aqueous alkaline deposition compositions are preferred in which the at least one metal deposited onto the metal surface is selected from the group consisting of manganese, silver, copper, cobalt, or nickel. The metal of the metal surface must be more noble than the metal being deposited, so that when the at least one metal is selected from the group consisting of manganese, copper, cobalt, or nickel, the metal of the treated metal surface cannot simultaneously be manganese, copper, cobalt, or nickel.

[0085] When the at least one metal source comprises a metal salt or when the at least one metal source is released in the deposition composition by anodic oxidation, 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, especially in ionic form.

[0086] Preferred are aqueous alkaline precipitation compositions in which the at least one metal is present in the composition in a total concentration of 0.1 wt.-% to 15 wt.-%, preferably 1 wt.-% to 12 wt.-%, more preferably 0.75 wt.-% to 5 wt.-%, even more preferably 1 wt.-% to 3 wt.-%, and most preferably 1 wt.-% to 2 wt.-% relative to the total mass of the composition.

[0087] With regard to the use of the aqueous alkaline deposition composition according to the second aspect, the above concentrations in the deposition composition also apply to at least one metal derived from at least one metal source, either by adding a salt to the deposition composition or by releasing the corresponding metal ion in the deposition composition by anodic oxidation.

[0088] Preferred is the use of the aqueous alkaline deposition composition of the present invention, where the substrate is a metal substrate, where a metal provides the metal surface to be treated, or a substrate comprising a metal surface, more preferably comprising a metal or metal alloy selected from the group comprising copper, nickel, aluminum, cobalt, manganese, zinc, lead, antimony, tin, rare earth metals, such as neodymium, copper-zinc alloys, copper-tin alloys, copper-nickel alloys, and aluminum-magnesium alloys.

[0089] Use of the aqueous alkaline deposition compositions of the present invention where the substrate comprises copper, nickel, aluminum, zinc, or zinc-coated steel is preferred.

[0090] Aqueous alkaline deposition compositions that do not contain anionic agents are preferred. It has been found through independent experiments that the addition of acids such as hydrochloric acid, sulfuric acid, bromic acid, mono-, di- or tricarboxylic acids, such as carboxylic acids, for example acetic acid or citric acid, alkylsulfonic acids, such as methanesulfonic acid, methane-disulfonic acid, methane-trisulfonic acid, arylsulfonic acids, such as tosylate compounds, and their metal salts, has an aggravating effect on deposition. It has been observed that the addition of anionic agents prevents or postpones the release of the deposited metal ions from the functionalized urea derivative-metal ion complex.

[0091] According to a third aspect, the present invention further provides a method for electroless deposition of a metal or metal alloy on a metallic surface of a metal substrate, comprising the steps of: (A) providing an aqueous alkaline deposition composition for electroless deposition of a metal or metal alloy on a metal surface of a metal substrate according to a first aspect; (B) contacting a metal substrate with the aqueous alkaline deposition composition such that a metal or metal alloy is electrolessly deposited on the metal surface of the metal substrate; The present invention relates to a method comprising the steps of:

[0092] According to a fourth aspect, the present invention further provides a method for electroless deposition of a metal or metal alloy on a metallic surface of a substrate, comprising the steps of: (A) providing an aqueous alkaline deposition composition for electroless deposition of a metal or metal alloy on a metal surface of a substrate according to the second aspect; (B) contacting a substrate with the aqueous alkaline deposition composition such that a metal or metal alloy is electrolessly deposited on the metallic surface of the substrate; The present invention relates to a method comprising the steps of:

[0093] The methods according to the third and fourth aspects ensure an efficient deposition process.

[0094] The process of the present invention is preferably carried out at a temperature between 20°C and 100°C, preferably between 30°C and 80°C, more preferably between 40°C and 70°C or between 40°C and 60°C, most preferably between 50°C and 60°C or at 50°C.

[0095] By carrying out the process in a preferred temperature range, a highly efficient precipitation reaction can be ensured.

[0096] Preferred is the process of the invention, in which the substrate to be treated comprises a metal substrate, preferably a metal substrate or a substrate comprising a metal surface comprises all metals and metal alloys used for immersion deposition which are more noble than gold and more noble than the metal to be deposited according to their standard electrochemical potential (measured against hydrogen by known methods), preferably excluding iron, chromium and nickel-chromium steel alloys (thus excluding, for example, silicon, titanium, tantalum and zirconium).

[0097] The method of the present invention is preferred, wherein the substrate to be treated comprises a metal or metal alloy selected from the group consisting of aluminum, copper, nickel, cobalt, manganese, zinc, lead, antimony, tin, rare earth metals such as neodymium, copper-zinc alloys, copper-tin alloys, copper-nickel alloys, and aluminum-magnesium alloys.

[0098] Preferred is the process of the present invention in which the metal or metal surface of the substrate being treated comprises copper, nickel, zinc, aluminum, zinc-coated steel and / or cobalt.

[0099] Thereby, the deposition efficiency of the method is tailored to allow efficient deposition of a wide variety of metal substrates.

[0100] In some cases, the method of the present invention is particularly preferred, where the substrate and its metal surface comprise aluminum or an aluminum alloy, preferably aluminum or an aluminum alloy. This is most preferred when the metal and metal alloy, respectively, for electroless deposition comprise, preferably are, nickel, manganese, copper, and / or alloys thereof.

[0101] The method of the invention is preferred, wherein no voltage is applied to the substrate during method step (B), meaning that no electric current is involved as an electron donor for reducing metal ions to metal or metal alloy during electroless deposition.

[0102] Moreover, the method of the present invention is preferred when the aqueous alkaline deposition composition is substantially free of, preferably free of, reducing agents for electroless deposition of metals and metal alloys, respectively, most preferably the metals and metal alloys, respectively, are or contain nickel and / or manganese.This also preferably applies to the aqueous alkaline deposition composition of the present invention in general.Therefore, conventional, e.g. chemical compounds for reducing metals and metal alloys, respectively, are preferably not required.

[0103] Instead, the method of the present invention is most preferred, in which the electroless deposition is immersion deposition. This means that the deposition involves a redox reaction involving the metal or metal alloy (preferably a metal or metal alloy as defined throughout this specification, more preferably nickel, manganese, and their respective alloys) and the surface of the substrate (preferably aluminum or aluminum alloy). In other words, immersion deposition involves an electron transfer between at least two metals, from a less noble metal to a more noble metal. By "more noble metal" is meant the view of the electrochemical series in this context that the redox potential of the complex of the metal ion to be deposited and the functionalized urea derivative is more noble than the metal of the metal surface, for example, it is found that the manganese ion complexed by the functionalized urea derivative of the present invention is more noble than the metallic zinc substrate. In the context of the present invention, the substrate (including its surface) and its metal surface are not considered as reducing agents, but are part of the redox reaction between the metal of the metal surface and the metal ion to be plated. Typically, such a type of metal deposition is called immersion deposition. Also typically, such metal deposition is preferably self-limiting, since the more metal or metal alloy is deposited thereby covering the substrate surface, the less access there is to the surface metal to drive the process forward.

[0104] Therefore, preferred is a process according to the invention, wherein the metals and metal alloys for deposition are different from the substrate, more particularly different from the metal or metal surface of the substrate.

[0105] During use of the deposition composition to deposit metal on a metal surface, the concentration of metal ions from the metal ion source decreases while the concentration of metal ions from the metal surface of the substrate increases in the deposition composition. The accumulated metal ions from the metal surface of the substrate (or metal substrate) form a precipitate and sink to the bottom of the deposition tank.

[0106] Therefore, further steps: (C) recycling the aqueous alkaline precipitation composition after process step (B), (C1) optionally increasing the temperature of the aqueous alkaline deposition composition to obtain an elevated temperature aqueous alkaline deposition composition; (C2) filtering the aqueous alkaline precipitation composition or the optionally elevated temperature aqueous alkaline precipitation composition to obtain a filtered aqueous alkaline precipitation composition; (C3) adding a source of metal ions and reapplying the filtered aqueous alkaline precipitation composition to process step (A); A method according to the invention comprising a step (C) comprising the steps of:

[0107] Any precipitate that forms can be removed from the solution by filtration or other equivalent methods.

[0108] Additionally, the decrease in metal concentration in the deposition composition due to deposition of the metal on the surface of the substrate can be balanced by adding more metal source to the deposition composition, e.g. by adding elemental metal (solid metal pieces) in the case of the method according to the third aspect, or by adding metal salts in the case of the method according to the fourth aspect, or by applying anodic oxidation.

[0109] The process of the invention is preferred, in which the precipitate formed in the aqueous alkaline precipitation composition during optional process step (C1) is removed from the aqueous alkaline precipitation composition during process step (C2) in order to obtain a filtered aqueous alkaline precipitation composition having reduced precipitate after process step (C2). The increase in temperature promotes the formation of the precipitate.

[0110] When the temperature is optionally increased, the process of the invention is preferably carried out at a temperature between 20°C and 100°C, preferably between 30°C and 80°C, more preferably between 40°C and 70°C or between 40°C and 60°C, even more preferably between 50°C and 60°C, most preferably at 50°C.

[0111] Removal of the precipitate from the aqueous alkaline deposition composition allows for efficient recovery of the metal ions removed from the treated metal surface.

[0112] The aqueous alkaline deposition composition can be replenished with precipitated metal ions by adding a source of metal ions according to process step (C3). The replenished and filtered aqueous alkaline deposition composition is then reapplied to process step (A).

[0113] Preferred is the process of the present invention, wherein the metal substrate provided in step (A) is formed as a flexible metal substrate, preferably as a flexible copper substrate, more preferably as a flexible copper-coated polymer.

[0114] In some other cases, a flexible foil is preferred, most preferably an aluminum foil. Most preferred is when the metal and metal alloy, respectively, for electroless deposition is or contains nickel.

[0115] The process of the present invention is preferred, in which the substrate realized during step (A) is formed as a copper clad laminate or resin, or a homogenous copper substrate.

[0116] By depositing metals or metal alloys on different types of substrates having different chemical and physical properties, the method can be applied in a wide range of applications and is therefore generally usable.

[0117] For example, for printed circuit boards (PCBs), copper-clad resins, especially polymers, can be used, or copper-clad glass can be used as the substrate. Alternatively, for general manufactured goods, copper-clad plastics or copper-clad sheet metal can be used as the substrate.

[0118] Preferred is the process of the invention, wherein steps (A) and / or (B) are carried out under stirring, preferably at a stirring speed of 20 rpm to 1,000 rpm, more preferably 50 rpm to 500 rpm, most preferably 100 rpm.

[0119] Preferred is a process according to the invention, wherein step (B) is carried out for a period of less than 2 hours, preferably less than 1 hour, more preferably less than 45 minutes, even more preferably less than 30 minutes, most preferably less than 15 minutes.

[0120] Preferred is the method of the invention, wherein step (B) is carried out for a period of from 1 minute to 2 hours, preferably from 5 minutes to 1.5 hours, more preferably from 15 minutes to 1 hour, most preferably from 50 minutes to 15 minutes.

[0121] The preferred stirring and time intervals of the method allow efficient deposition and they can be individually adjusted according to the metal substrate used.

[0122] The method includes a step (P) performed before the step (B), and the step (P) is (P1) pre-rinsing the substrate with an acidic solution, preferably comprising sulfuric acid, to obtain a pre-rinsed substrate; (P2) washing the pre-rinsed substrate with a washing solution preferably comprising demineralized water to obtain a washed substrate; wherein the washed substrate is contacted with said aqueous alkaline deposition composition during step (B); The method of the present invention is preferred.

[0123] The step of pre-rinsing the substrate with an acidic solution and subsequent washing step can ensure efficient cleaning of the surface onto which the metal is deposited during step (B), thereby enhancing the effectiveness of the method. Pre-rinsing the substrate can efficiently eliminate any potential corrosion of the substrate and / or surface contamination of the substrate prior to transferring the substrate into the aqueous alkaline deposition composition.

[0124] However, method step (P) is an optional method step and the method according to the third and / or fourth aspect of the invention may also be carried out without method step (P).

[0125] Preferably, what has been stated above in relation to the aqueous alkaline precipitation compositions according to the first and second aspects of the invention applies equally to the processes according to the third and fourth aspects of the invention.

[0126] In certain highly preferred embodiments, the method of the present invention relates to electroless immersion nickel deposition (i.e., without a separate reducing agent) in which the aqueous alkaline deposition composition comprises nickel ions for electrolessly depositing nickel or nickel alloys onto aluminum or aluminum alloys.

[0127] Preferably, in this particular embodiment, the method of the present invention does not include a pretreatment of the aluminum and aluminum alloy, respectively, with a fluoride-containing pretreatment composition prior to step (B), or includes only a single treatment step of the aluminum and aluminum alloy, respectively, with a fluoride-containing pretreatment composition prior to step (B). Most preferably, no pretreatment with a fluoride is performed.

[0128] Preferably, in this particular embodiment, the method of the present invention does not include a pretreatment of the aluminum and aluminum alloy, respectively, with a pretreatment composition comprising zinc prior to step (B), or includes only a single treatment step of the aluminum and aluminum alloy, respectively, with a pretreatment composition comprising zinc prior to step (B). Most preferably, no pretreatment with zinc is performed.

[0129] Own experiments have shown that this particular embodiment allows a significant reduction in pretreatment effort compared to typical plating in aluminum / aluminum alloy procedures. In many cases, other typical pretreatments, including more than one contact with a pretreatment composition containing fluoride and / or zinc, commonly known as zincate pretreatment, can be avoided. Rather, the compound of formula I and its salts not only allow effective stabilization of nickel ions in the aqueous alkaline deposition composition, but also realize a pretreatment effect on the aluminum / aluminum alloy surface by at least partially dissolving the harmful passivation layer thereon.

[0130] Preferably, in this particular embodiment, the method of the present invention does not include pretreatment of the aluminum and aluminum alloy, respectively, with a pretreatment composition comprising nitric acid, prior to step (B).

[0131] In this particular embodiment, the method of the invention is preferred, in step (B), wherein the deposited nickel or nickel alloy has a layer thickness in the range of 4 nm to 100 nm, preferably 7 nm to 80 nm, more preferably 10 nm to 60 nm, even more preferably 15 nm to 40 nm and most preferably 20 nm to 30 nm.

[0132] In this particular embodiment, the method of the invention is preferred, wherein step (B) is carried out for a time in the range of from 1 minute 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, and most preferably from 5 minutes to 15 minutes.

[0133] In this particular embodiment, preferred is a process of the invention comprising, after step (B), a step (B-1) of 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.

[0134] Thus, in step (B-1) further nickel or nickel alloy is electrolessly deposited onto the nickel and nickel alloy, respectively, deposited by immersion deposition in step (B).

[0135] As a result, in steps (B) and (B-1), two successive nickel layers are deposited one on top of the other.

[0136] Preferably, what has been said above regarding the first and second aspects of the invention applies equally to the specific aspects discussed above.

[0137] Preferably, the electrolessly deposited nickel and nickel alloys are derived from either nickel ions or metallic nickel as the nickel source, most preferably metallic nickel. Since compound (a) dissolves metallic nickel so that nickel ions are produced, no additional counter ions are added to the aqueous alkaline deposition composition. This is highly beneficial.

[0138] According to a fifth aspect, the present invention further relates to a metallic substrate having a deposited metal or metal alloy layer on a surface of the substrate, the deposited metal or metal alloy layer being obtained by a method for electroless deposition of a metal or metal alloy on a surface of a substrate according to the third or fourth aspect.

[0139] Preferably, what has been stated above, preferably as preferred, with respect to the use of the aqueous alkaline deposition compositions according to the first and second aspects of the invention and the methods according to the third and fourth aspects of the invention applies analogously to the substrate according to the fifth aspect of the invention. EXAMPLES

[0140] 1. Silver deposition on the surface of the substrate Preparation of Aqueous Alkaline Silver Deposition Compositions 25.00g (0.232mol) of silver powder and a magnetic stir bar were placed in a 2000ml beaker. Then, 200.00g (0.724mol) of 1,3-bis(3-(1H-imidazol-1yl)propyl)urea was added and dissolved in 1775ml of deionized water. Stirring was performed at 50°C for 5 hours at a speed of 150 rpm. At the end of the reaction time, the liquid part turned blue-purple. A small amount of undissolved silver powder was still at the bottom of the beaker. Water evaporated during the 5 hours of reaction time and was replenished with deionized water. The yield obtained is 2000.00g (100.00%). After preparation, the aqueous alkaline silver deposition composition has a pH between 9-11 and is ready for electroless deposition of silver on the surface of the substrate.

[0141] Electroless Deposition of Silver on the Surface of Copper-Plated ABS Substrates 2000 g of the aqueous alkaline silver deposition composition prepared above was heated to 50° C. for 20 minutes in a 2000 ml beaker with a stirring speed of 150 rpm. The aqueous alkaline silver deposition composition was then transferred to a 2000 ml graduated cylinder containing a magnetic stir bar. The copper-plated ABS substrate was immersed in 5% sulfuric acid for 10 seconds, then rinsed with copious amounts 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 thoroughly with deionized water and dried with compressed air. The silver layer thickness was determined to be 0.084 μm by XRF analysis.

[0142] Electroless deposition of silver on the surface of copper sheets. 2000g of the aqueous alkaline silver deposition composition prepared above was heated to 50°C for 20 minutes in a 2000ml beaker with a stirring speed of 150 rpm. A copper plate was immersed in 5% sulfuric acid for 10 seconds, then rinsed with a large amount of deionized water, and directly coated by immersing the copper plate 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 plate was thoroughly rinsed with deionized water and dried with compressed air. The silver layer thickness was determined to be 0.089 μm by XRF analysis. The silver surface did not tarnish over time. No tarnish could be found after 12 weeks. Furthermore, fingerprints did not remain on the surface or could be easily wiped off.

[0143] Electroless deposition of silver on the surface of brass plates. 2000 g of the aqueous alkaline silver deposition composition prepared above was heated to 50° C. for 20 minutes in a 2000 ml beaker with a stirring speed of 150 rpm. A brass plate was immersed in 5% sulfuric acid for 10 seconds, then rinsed with copious amounts of deionized water, and directly coated by immersing the brass plate 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 plate was rinsed thoroughly with deionized water and dried with compressed air. The silver layer thickness was determined to be 0.128 μm by XRF analysis.

[0144] Electroless Deposition of Silver on the Surface of Copper-Plated FR4 Panels 2000 g of the aqueous alkaline silver deposition composition prepared above was heated to 50° C. for 20 minutes in a 2000 ml beaker with a stirring speed of 150 rpm. A copper-plated FR4 panel was immersed in 5% sulfuric acid for 10 seconds, then rinsed with copious amounts of deionized water, and directly coated 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 thoroughly with deionized water and dried with compressed air. The silver layer thickness was determined to be 0.775 μm by XRF analysis.

[0145] Electroless Deposition of Silver on the Surface of Copper Plated HMP Panels 2000 g of the aqueous alkaline silver deposition composition prepared above was heated to 50° C. in a 2000 ml beaker for 20 minutes with a stirring speed of 150 rpm. A copper plated HMP panel was immersed in 5% sulfuric acid for 10 seconds, then rinsed with copious amounts of deionized water, and directly coated by immersing the copper plated HMP panel in the aqueous alkaline silver deposition composition at 25% immersion depth for 15 minutes at 50° C., at 50% immersion depth for an additional 15 minutes, and at 75% immersion depth for an additional 15 minutes at 50° C. The composition was stirred at about 150 rpm during coating. After coating, the copper plated HMP panel was rinsed thoroughly with deionized water and dried with compressed air. The silver layer thickness was determined by XRF analysis to be 0.087 μm after 15 minutes, 0.141 μm after 30 minutes, and 0.178 μm after 45 minutes.

[0146] Electroless long-term deposition of silver on the surface of copper plated HMP panels 2000 g of the aqueous alkaline silver deposition composition prepared above was heated to 50° C. for 20 minutes in a 2000 ml beaker with a stirring speed of 150 rpm. A copper plated HMP panel was directly coated by immersing it in 5% sulfuric acid for 10 seconds, then rinsing with copious amounts of deionized water, and immersing the copper plated HMP panel in the aqueous alkaline silver deposition composition at 75% immersion depth for 20 hours at 50° C. The composition was stirred at about 150 rpm during coating. After coating, the copper plated HMP panel was rinsed thoroughly with deionized water and dried with compressed air. The silver layer thickness was determined to be 0.428 μm by XRF analysis.

[0147] Electroless deposition of silver on the surface of copper-plated glass panels. 2000 g of the aqueous alkaline silver deposition composition prepared above was heated to 50° C. for 20 minutes in a 2000 ml beaker with a stirring speed of 150 rpm. A copper-plated glass panel was immersed in 5% sulfuric acid for 10 seconds, then rinsed with copious amounts of deionized water, and directly 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 thoroughly with deionized water and dried with compressed air. The silver layer thickness was determined to be 0.059 μm by XRF analysis.

[0148] Electroless deposition of silver on the surface of copper-plated pieces of wafers. 2000 g of the aqueous alkaline silver deposition composition prepared above was heated to 50° C. for 20 minutes in a 2000 ml beaker with a stirring speed of 150 rpm. A copper-plated piece of wafer was immersed in 5% sulfuric acid for 10 seconds, then rinsed with copious amounts of deionized water, and directly coated by immersing the copper-plated piece of 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 thoroughly with deionized water and dried with compressed air. The silver layer thickness was determined to be 0.137 μm by XRF analysis.

[0149] Electroless deposition of silver on the surface of high frequency aluminium sockets. 2000g of the aqueous alkaline silver deposition composition prepared above was heated to 50°C for 20 minutes in a 2000ml beaker with a stirring speed of 150 rpm. The radio frequency aluminum socket was immersed in 5% sulfuric acid for 15 seconds until gas evolution began over the entire area. The radio frequency aluminum socket was then rinsed with copious amounts of deionized water and the composition was directly coated by immersing the radio frequency aluminum socket in the aqueous alkaline silver deposition composition at 50°C for 5 minutes, with stirring at approximately 150 rpm during coating. After coating, the radio frequency aluminum socket was thoroughly rinsed with deionized water and dried with compressed air. The silver layer thickness was determined to be 0.085 μm by XRF analysis.

[0150] Electroless deposition of silver on the surface of high frequency aluminium sockets. 2000 g of the aqueous alkaline silver deposition composition prepared above was heated to 50° C. for 20 minutes in a 2000 ml beaker with a stirring speed of 150 rpm. The radio frequency aluminum socket was immersed in 5% sulfuric acid for 15 seconds until gas evolution began over the entire area. The radio frequency aluminum socket was then rinsed with a large amount of deionized water and directly coated by immersing the radio frequency aluminum socket in the aqueous alkaline silver deposition composition at 50° C. for 15 minutes while stirring the composition at approximately 150 rpm. After coating, the radio frequency aluminum socket was thoroughly rinsed with deionized water and dried with compressed air. The silver layer thickness was determined to be 0.352 μm by XRF analysis.

[0151] The aqueous alkaline silver deposition composition prepared above deposits translucent to opaque, matte to glossy silver layers on a variety of different substrates used above, which no longer tarnish with time, and gives a silver deposit layer of 0.05μm to 0.75μm at temperatures between 30℃ to 50℃ after a coating time of 5 minutes to 60 minutes.

[0152] Use and recycling of aqueous alkaline silver deposition compositions During use of the deposition composition, the concentration of metal ions at the metal surface of the substrate (as described in the examples above) increases in the deposition composition while the concentration of available silver ions from the source of silver ions decreases.

[0153] To recycle the deposition composition or a part thereof, the deposition composition is filtered to separate the precipitate of metal ions originating from the metal surface. The filtered aqueous alkaline deposition composition is replenished by adding silver powder essentially as described in the preparation of the aqueous alkaline silver deposition composition above. As a result, the silver powder is dissolved and thus provides silver ions. The silver ions are complexed with the compounds as described above. Finally, the replenished and filtered aqueous alkaline deposition composition is to be used again in the process step (A).

[0154] 2. Nickel deposition on the surface of the substrate Preparation of Aqueous Alkaline Nickel Deposition Composition 25.00 g (0.426 mol) of nickel anode spheres (approximately 8 mm in diameter) and a small magnetic stir bar were carefully placed in 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 dissolved in 1775 ml of deionized water. The composition was stirred at 50° C. for 168 hours at a speed of 150 rpm to prevent the nickel anode spheres from moving. At the end of the reaction time, the composition turned blue-green. A small amount of undissolved nickel anode spheres was still at the bottom of the beaker. Water evaporated during the 168-hour reaction time and was replenished with deionized water. The yield obtained 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 electroless deposition of nickel on the surface of the substrate.

[0155] Electroless Deposition of Nickel on the Zinc Surface of Galvanized Steel Sheets. 2000 g of the aqueous alkaline nickel deposition composition prepared above was heated to 40° C. in a 2000 ml beaker with a stirring speed of 150 rpm for 60 minutes. The galvanized steel sheet was immersed in 5% sulfuric acid for 15 seconds until gas evolution began over the entire area. The galvanized steel sheet was then rinsed with copious amounts of deionized water and directly coated by immersing the 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 galvanized steel sheet was rinsed thoroughly with deionized water and dried with compressed air. The nickel layer thickness was determined to be 0.018 μm by XRF analysis.

[0156] Electroless Deposition of Nickel on the Zinc Surface of Galvanized Steel Sheets. 2000 g of the aqueous alkaline nickel deposition composition prepared above was heated to 60° C. in a 2000 ml beaker with a stirring speed of 150 rpm for 50 minutes. The galvanized steel sheet was immersed in 5% sulfuric acid for 15 seconds until gas evolution began over the entire area. The galvanized steel sheet was then rinsed with copious amounts of deionized water and directly coated by immersing the 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 galvanized steel sheet was rinsed thoroughly with deionized water and dried with compressed air. The nickel layer thickness was determined to be 0.029 μm by XRF analysis.

[0157] Electroless Deposition of Nickel on Aluminum Connector Surfaces. 1000 g of the aqueous alkaline nickel deposition composition prepared above was heated to 60° C. for 38 minutes in a 2000 ml beaker with a stirring speed of 150 rpm. The aluminum connector was directly coated by immersing it 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 thoroughly with deionized water and dried with compressed air. The nickel layer thickness was determined to be 0.013 μm by FIB analysis.

[0158] Electroless Deposition of Nickel on Aluminum Connector Surfaces. Electroless deposition of nickel on the surface of the aluminum connector followed by chemical deposition (i.e. using a reducing agent) of nickel on the surface of the aluminum connector.

[0159] 1000 g of the aqueous alkaline nickel deposition composition prepared above was heated to 60° C. in a 2000 ml beaker for 38 minutes with a stirring speed of 150 rpm. The aluminum connector was directly coated by immersing it in the aqueous alkaline nickel deposition composition for 15 minutes at 60° C. The composition was stirred at approximately 150 rpm during coating. After coating, the aluminum connector was rinsed thoroughly with deionized water and dried with compressed air.

[0160] 500 g of aqueous chemical nickel deposition composition (Nichem MP 1188 available from Atotech Deutschland GmbH) was heated to 88° C. for 44 minutes in a 1000 ml beaker with a stirring speed of 150 rpm. The nickel immersion coated aluminum connector was directly coated by coating the 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 thoroughly with deionized water and dried with compressed air. The immersion nickel layer thickness was determined to be 0.016 μm by FIB analysis.

[0161] Comparative Example - Electroless Deposition of Nickel on the Surface of Aluminum Connectors To a 1000 ml beaker containing a magnetic stir bar, 250 ml deionized water was added, followed by 5.50 g of nickel(II) sulfate and then 15.00 g of ammonium chloride, with vigorous stirring. 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 it in the aqueous chemical 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 thoroughly with deionized water and dried with compressed air. The nickel layer thickness was determined to be 0.032 μm by FIB analysis. The resulting Ni immersion layer exhibited poor homogeneity and defects.

[0162] Aqueous alkaline nickel deposition compositions deposit translucent to opaque, dull to shiny nickel layers on aluminum, zinc, and tin substrates. Depending on the surface properties of the base material, these can be dull to highly polished. At temperatures between 40°C and 60°C, in 60 minutes, nickel deposit layers of 0.02 μm to 0.03 μm are obtained that no longer tarnish with time.

[0163] Use and recycling of aqueous alkaline nickel deposition compositions During use of the deposition composition, the concentration of metal ions at the metal surface of the substrate (as described in the examples above) increases in the deposition composition while the concentration of available nickel ions from the source of nickel ions decreases.

[0164] To recycle the deposition composition or a part of it, the deposition composition was filtered to separate the precipitate of metal ions originating from the metal surface. The filtered aqueous alkaline deposition composition was replenished by adding nickel powder essentially as described in the preparation of the aqueous alkaline nickel deposition composition above. As a result, the nickel powder was dissolved and thus provided nickel ions. The nickel ions were complexed with the compounds as described above. Finally, the replenished and filtered aqueous alkaline deposition composition was to be used again in process step (A).

[0165] 3. Manganese deposition on the surface of the substrate Preparation of Aqueous Alkaline Manganese Deposition Composition 25.00 g (0.455 mol) of manganese pieces 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 dissolved in 1775 ml of deionized water. Stirring was performed at 30° C. for 60 hours at a speed of 150 rpm. The temperature of the composition was prevented from rising above 40° C. to avoid an uncontrolled autocatalytic reaction in which manganese would exothermically dissolve with strong hydrogen evolution. At the end of stirring, the liquid composition turned light blue in color. A small amount of undissolved manganese pieces was still at the bottom of the beaker. Water evaporated during the 60-hour reaction time and was replenished with deionized water. The yield obtained was 2000.00 g (100.00%). Once prepared, the aqueous alkaline manganese deposition composition has a pH between 9 and 11 and is ready for the electroless deposition of manganese onto the surface of a substrate.

[0166] Electroless Deposition of Manganese on the Zinc Surface of Galvanized Steel Sheets. 2000 g of the aqueous alkaline manganese deposition composition prepared above was heated to 30° C. in a 2000 ml beaker with a stirring speed of 150 rpm for 35 minutes. A galvanized steel sheet with dimensions of 70×12×0.2 mm was immersed in 5% sulfuric acid for 15 seconds until gas evolution began over the entire area. The galvanized steel sheet was then removed, rinsed with copious amounts of deionized water, and the galvanized steel sheet was directly coated by immersing it 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 galvanized steel sheet was thoroughly rinsed with deionized water and dried with compressed air. The manganese layer thickness was determined to be 0.012 μm by XRF analysis.

[0167] Electroless Deposition of Manganese on the Zinc Surface of Galvanized Steel Sheets. 2000 g of the aqueous alkaline manganese deposition composition prepared above was heated to 30° C. in a 2000 ml beaker with a stirring speed of 150 rpm for 18 minutes. A galvanized steel sheet with dimensions of 70×70 mm was immersed in 5% sulfuric acid for 10 seconds until gas evolution began over the entire area. The galvanized steel sheet was then removed, rinsed with copious amounts of deionized water, and the galvanized steel sheet was directly coated by immersing it 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 galvanized steel sheet was rinsed with deionized water and dried with compressed air. The manganese layer thickness was determined to be 0.111 μm by XRF analysis.

[0168] Electroless Deposition of Manganese on Aluminum Connector Surfaces. 500 g of the aqueous alkaline manganese deposition composition prepared above was heated to 30° C. for 12 minutes in a 1000 ml beaker with a stirring speed of 150 rpm. Aluminum connectors were directly coated by immersing them 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 connectors were rinsed thoroughly with deionized water and dried with compressed air. The manganese layer thickness was determined to be 0.019 μm by FIB analysis.

[0169] Electroless deposition of manganese on the surface of an aluminum connector followed by chemical deposition of nickel on the surface of the aluminum connector 500 g of the aqueous alkaline manganese deposition composition prepared above was heated to 30° C. in a 1000 ml beaker for 12 minutes with a stirring speed of 150 rpm. Aluminum connectors were directly coated by immersing them in the aqueous alkaline manganese deposition composition for 15 minutes at 30° C. The composition was stirred at approximately 150 rpm during coating. After coating, the aluminum connectors were rinsed thoroughly with deionized water and dried with compressed air.

[0170] 500 g of aqueous chemical nickel deposition composition (Nichem MP 1188 available from Atotech Deutschland GmbH) was heated to 88° C. for 44 minutes in a 1000 ml beaker with a stirring speed of 150 rpm. The nickel immersion coated aluminum connector was directly coated by coating the 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 thoroughly with deionized water and dried with compressed air. The nickel layer thickness was determined to be 0.015 μm by FIB analysis.

[0171] The aqueous alkaline manganese deposition composition deposits a translucent to opaque, gray to pinkish manganese layer on aluminum and zinc that becomes silvery when heated strongly. Depending on the surface condition of the aluminum or zinc surface, the deposit layer can be dull to highly polished. A manganese layer of 0.01 μm is obtained in 60 minutes at 30°C.

[0172] Use and recycling of aqueous alkaline manganese deposition compositions During use of the deposition composition, the concentration of metal ions at the metal surface of the substrate (as described in the examples above) increases in the deposition composition while the concentration of available manganese ions from the source of manganese ions decreases.

[0173] To recycle the deposition composition or a part of it, the deposition composition is filtered to separate the precipitate of metal ions originating from the metal surface. The filtered aqueous alkaline deposition composition is replenished by adding manganese powder essentially as described in the preparation of the aqueous alkaline manganese deposition composition above. As a result, the manganese powder is dissolved and thus provides manganese ions. The manganese ions are complexed with the compounds as described above. Finally, the replenished and filtered aqueous alkaline deposition composition is to be used again in process step (A).

[0174] 4. Cobalt deposition on the surface of the substrate Preparation of Aqueous Alkaline Cobalt Deposition Composition 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 dissolved in 700 ml of deionized water. Stirring was performed at a speed of 150 rpm at 50° C. for 24 hours. At the end of the reaction time, the composition turned pink in color. A small amount of undissolved cobalt powder was still present at the bottom of the beaker. The water evaporated during the 24-hour reaction time and was replenished with deionized water. The yield obtained 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 electroless deposition of cobalt on the surface of the substrate.

[0175] Electroless deposition of cobalt on the surface of aluminum perforated plates. 2000 g of the aqueous alkaline cobalt deposition composition prepared above was heated to 50° C. in a 2000 ml beaker with a stirring speed of 150 rpm for 36 minutes. An aluminum perforated plate was immersed in 5% sulfuric acid for 10 seconds, then rinsed with a large amount of deionized water, and directly coated by immersing the aluminum perforated plate in the aqueous alkaline cobalt deposition composition at 50° C. for 15 minutes at 90% immersion depth, another 15 minutes at 60% immersion depth, and another 15 minutes at 30% immersion depth. The composition was stirred at about 150 rpm during coating. After coating, the aluminum perforated plate was thoroughly rinsed with deionized water and dried with compressed air. By XRF analysis, the cobalt layer thickness was determined as follows: the cobalt layer after 15 minutes was not detectable, the cobalt layer after 30 minutes had a thickness of 0.003 μm, and the cobalt layer after 45 minutes had a thickness of 0.011 μm.

[0176] Electroless deposition of cobalt on the zinc surface of galvanized steel sheets. 2000 g of the aqueous alkaline cobalt deposition composition prepared above was heated to 50° C. in a 2000 ml beaker with a stirring speed of 150 rpm for 39 minutes. A galvanized steel sheet was immersed in 5% sulfuric acid for 10 seconds, then rinsed with copious amounts of deionized water, and directly coated by immersing the galvanized steel sheet in the aqueous alkaline cobalt deposition composition at 50° C. for 15 minutes at 90% immersion depth, another 15 minutes at 60% immersion depth, and another 15 minutes at 30% immersion depth. The composition was stirred at about 150 rpm during coating. After coating, the galvanized steel sheet was thoroughly rinsed with deionized water and dried with compressed air. By XRF analysis, the cobalt layer thickness was determined as follows: cobalt layer after 15 minutes: 0.017 μm, cobalt layer after 30 minutes: 0.024 μm, and cobalt layer after 45 minutes: 0.028 μm.

[0177] The aqueous alkaline cobalt deposition composition deposits a translucent to opaque cobalt layer on aluminum and zinc, which no longer tarnishes. The shiny layer shines in all spectral colors depending on the incidence of light. This effect persists even after 6 months of storage under atmospheric conditions. Depending on the surface condition of the aluminum or zinc surface, the cobalt deposit layer can be matte to very shiny. A uniformly closed cobalt deposit layer of 0.003 to 0.028 μm is obtained in 5 to 60 minutes at 50 °C.

[0178] Use and recycling of aqueous alkaline cobalt deposition compositions During use of the deposition composition, the concentration of metal ions at the metal surface of the substrate (as described in the examples above) increases in the deposition composition while the concentration of available cobalt ions from the source of cobalt ions decreases.

[0179] To recycle the deposition composition or a part thereof, the deposition composition is filtered to separate the precipitate of metal ions originating from the metal surface. The filtered aqueous alkaline deposition composition is replenished by adding cobalt powder essentially as described in the preparation of the aqueous alkaline cobalt deposition composition above. As a result, the cobalt powder is dissolved and thus provides cobalt ions. The cobalt ions are complexed with the compounds as described above. Finally, the replenished and filtered aqueous alkaline deposition composition is to be used again in process step (A).

[0180] 5. Copper deposition on the surface of the substrate Preparation of Aqueous Alkaline Copper Deposition Compositions 26.411 g (0.416 mol) of copper foil pieces (approximately 1×1 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 dissolved in 2139.31 ml of deionized water. Stirring was performed at a speed of 150 rpm at 50° C. for 60 hours. At the end of the reaction time, the composition turned light blue. A small amount of undissolved copper foil pieces was still at the bottom of the beaker. Water evaporated during the 60-hour reaction time and was replenished with deionized water. The yield obtained 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 electroless deposition of copper on the surface of the substrate.

[0181] Electroless deposition of copper on the surface of aluminum perforated plates. 2000g of the aqueous alkaline copper deposition composition prepared above was heated to 50°C in a 2000ml beaker with a stirring speed of 150 rpm for 39 minutes. An aluminum perforated plate was immersed in 5% sulfuric acid for 10 seconds, then rinsed with a large amount of deionized water, and directly coated by immersing the aluminum perforated plate in the aqueous alkaline copper deposition composition at 50°C for 15 minutes at 90% immersion depth, another 15 minutes at 60% immersion depth, and another 15 minutes at 30% immersion depth. The composition was stirred at about 150 rpm during coating. After coating, the aluminum perforated plate was thoroughly rinsed with deionized water and dried with compressed air. By XRF analysis, the copper layer thickness was determined as follows: copper layer after 15 minutes: 0.004 μm, copper layer after 30 minutes: 0.006 μm, and copper layer after 45 minutes: 0.007 μm.

[0182] Electroless Deposition of Copper on Aluminum Foil Surfaces 2000 g of the aqueous alkaline copper deposition composition prepared above was heated to 60° C. in a 2000 ml beaker with a stirring speed of 150 rpm for 38 minutes. Aluminum foil was immersed in 5% sulfuric acid for 10 seconds, then rinsed with a large amount of deionized water, and directly coated by immersing the aluminum foil in the aqueous alkaline copper deposition composition at 60° C. for 15 minutes at 90% immersion depth, another 15 minutes at 60% immersion depth, and another 15 minutes at 30% immersion depth. The composition was stirred at about 150 rpm during coating. After coating, the aluminum foil was thoroughly rinsed with deionized water and dried with compressed air. By XRF analysis, the copper layer thickness was determined as follows: copper layer after 15, 30 and 45 minutes: 0.007 μm.

[0183] Electroless Deposition of Copper on Aluminum Connector Surfaces. 500 g of the aqueous alkaline copper deposition composition prepared above was heated to 50° C. in a 1000 ml beaker with a stirring speed of 150 rpm for 25 minutes. An aluminum connector with dimensions of 30.7×29.5 mm was rinsed with deionized water and immersed in 5.00% sulfuric acid for 60 seconds. After 20 seconds, gas evolution over the entire area started. The aluminum connector was then removed, rinsed with a large amount of deionized water, and the aluminum connector was directly coated by immersing it 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 thoroughly rinsed with deionized water and dried with compressed air. A homogeneous Cu layer was obtained. A copper layer thickness of 16.97 μm was determined by FIB analysis.

[0184] Electroless Deposition of Copper on Aluminum Surface of Aluminum Panels 1000 g of the aqueous alkaline copper deposition composition prepared above was heated to 50° C. in a 1000 ml beaker with a stirring speed of 150 rpm for 25 minutes. An aluminum panel with dimensions of 127×44.3×0.6 mm was rinsed with deionized water and immersed in 5,00% sulfuric acid for 60 seconds. After 20 seconds, gas evolution over the entire area started. The aluminum panel was then removed, rinsed with copious amounts of deionized water, and directly 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 thoroughly rinsed with deionized water and dried with compressed air. An inhomogeneous and porous Cu layer was obtained. A copper layer thickness of 121,92 μm was determined by FIB analysis.

[0185] Electroless Deposition of Copper on the Zinc Surface of Galvanized Steel Sheets. 2000 g of the aqueous alkaline copper deposition composition prepared above was heated to 60° C. in a 2000 ml beaker with a stirring speed of 150 rpm for 35 minutes. A galvanized steel sheet was immersed in 5% sulfuric acid for 10 seconds, then rinsed with a large amount of deionized water, and directly coated by immersing the galvanized steel sheet in the aqueous alkaline copper deposition composition at 60° C. for 15 minutes at 90% immersion depth, another 15 minutes at 60% immersion depth, and another 15 minutes at 30% immersion depth. The composition was stirred at about 150 rpm during coating. After coating, the galvanized steel sheet was thoroughly rinsed with deionized water and dried with compressed air. By XRF analysis, the copper layer thickness was determined as follows: copper layer after 15 minutes: 0.023 μm, copper layer after 30 minutes: 0.037 μm, and copper layer after 45 minutes: 0.042 μm.

[0186] Electroless Deposition of Copper on Aluminum Connector Surfaces. 500 g of the aqueous alkaline copper deposition composition prepared above was heated to 50° C. for 26 minutes in a 1000 ml beaker with a stirring speed of 150 rpm. Aluminum connectors were directly coated by immersing them 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 connectors were rinsed thoroughly with deionized water and dried with compressed air. The copper layer thickness was determined to be 0.017 μm by FIB analysis.

[0187] Electroless deposition of copper on the surface of aluminum connectors followed by electrochemical deposition of copper on the surface of aluminum connectors 500 g of the aqueous alkaline copper deposition composition prepared above was heated to 50° C. for 26 minutes in a 1000 ml beaker with a stirring speed of 150 rpm. Aluminum connectors were directly coated by immersing them 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 connectors were rinsed thoroughly with deionized water and dried with compressed air.

[0188] 500 g of Cupracid UP600 without brightener (available from Atotech Deutschland GmbH) was added to a 1000 ml beaker under gentle stirring. A 50×70×2 mm titanium grid was used as the anode. An aluminum connector was attached to the aluminum wire and a current of 3 A / dm 2 The aluminum connectors were immersed in an acid copper bath at 20°C for 20 minutes. The distance between the aluminum connector and the titanium grid was 4 cm. After plating, the immersion copper-coated and electrochemical copper-plated connectors were rinsed with deionized water and dried with compressed air. The resulting copper layer thickness was very homogeneous and closed.

[0189] The aqueous alkaline copper deposition composition deposits translucent to opaque copper layers on aluminum and zinc, which do not tarnish any more. Depending on the surface condition of the aluminum or zinc surface, the copper layer can be matte to highly glossy. At 50°C to 75°C, a uniformly closed layer of 0.004 to 0.042 μm can be obtained in 5 to 60 minutes.

[0190] Use and recycling of aqueous alkaline copper deposition compositions During use of the deposition composition, the concentration of metal ions at the metal surface of the substrate (as described in the examples above) increases in the deposition composition while the concentration of available copper ions from the source of copper ions decreases.

[0191] To recycle the deposition composition or a part thereof, the deposition composition is filtered to separate the precipitate of metal ions originating from the metal surface. The filtered aqueous alkaline deposition composition is replenished by adding copper powder essentially as described in the preparation of the aqueous alkaline copper deposition composition above. As a result, the copper powder is dissolved and thus provides copper ions. The copper ions are complexed with the compounds as described above. Finally, the replenished and filtered aqueous alkaline deposition composition is to be used again in the process step (A).

Claims

1. 1. Use of an aqueous alkaline deposition composition for the electroless deposition of a metal or metal alloy on a metal surface of a substrate, said composition comprising: (a) Formula I: 【Chemistry 1】 (In the formula, X is selected as oxygen, R 1 and R 2 are independently selected as the nitrogen-containing heteroaromatic compound; R 1 and R 2 may be the same or different, m is an integer from 2 to 6; n is an integer from 2 to 6, wherein m and n may be the same or different) and / or salts thereof, and (b) at least one metal ion source that provides metal ions to be deposited as a metal on 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; wherein the compound of formula I and / or its salt is present in the composition in a total concentration of 1 wt.-% to 20 wt.-% relative to the total mass of the composition; the metal or metal alloy to be deposited is selected from the group consisting of silver, nickel, manganese, cobalt, and copper; the at least one metal ion source (ii) a metal anodic material in contact with the aqueous alkaline deposition composition, which is oxidized by applying an electric current to the anode to enable an anodization process, resulting in the release of metal ions into the aqueous alkaline deposition composition; (iii) a solid metal piece in contact with the aqueous alkaline deposition composition, the solid metal piece being oxidized by an oxidizing agent dissolved in the aqueous alkaline deposition composition to enable an oxidation process, resulting in the release of metal ions into the aqueous alkaline deposition composition; The use of any one of the following:

2. R 1 and R 2 But C 1 ~C 6 2. The use according to claim 1, wherein the imidazole is selected as a substituted and / or unsubstituted imidazole optionally comprising at least one substituent selected as an alkyl.

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

4. 2. The use according to claim 1, wherein the aqueous alkaline deposition composition has a pH value of from 7.1 to 13.

5. The functionalized urea derivative and / or salt thereof is m is 3 and n is 3, R 1 But C 1 ~C 6 imidazole optionally containing at least one substituent selected as alkyl; R 2 But C 1 ~C 6 2. The use according to claim 1, wherein the compound is selected as a compound having formula I and / or a salt thereof, which is an imidazole optionally containing at least one substituent selected as alkyl.

6. 2. The use according to claim 1, wherein the compound of formula I and / or its salt is present in the composition in a total concentration of 2 wt.-% to 15 wt.-%.

7. 10. The use of claim 1, wherein the oxidizing agent for oxidizing the solid metal pieces of the aqueous alkaline deposition composition comprises oxygen dissolved in the aqueous alkaline deposition composition.

8. 2. The use 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.

9. 2. The use according to claim 1, wherein the at least one metal ion source supplying metal ions is present in the composition in a total concentration of 0.1 wt.-% to 15 wt.-% relative to the total mass of the composition.

10. The use according to claim 1, wherein the composition does not contain a reducing agent and / or an anionic agent.

11. The use of claim 1, wherein the metal surface of the substrate comprises a metal or metal alloy selected from the group consisting of aluminum, copper, nickel, cobalt, manganese, zinc, lead, antimony, tin, rare earth metals, copper-zinc alloys, copper-tin alloys, copper-nickel alloys, and aluminum-magnesium alloys.

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