阅读说明：本技术 用于电解沉积铜涂层的水性酸性铜电镀浴及方法 (Aqueous acidic copper electroplating bath and method for electrolytically depositing copper coatings ) 是由 P.瓦赫特 S.克雷奇默 于 2018-05-31 设计创作，主要内容包括：水性酸性铜电镀浴,其包含：铜离子；至少一种酸；卤离子；至少一种含硫化合物,其选自3-巯基丙基磺酸钠、双(钠磺基丙基)二硫化物、3-(N,N-二甲基硫代氨基甲酰基)-硫基丙磺酸或其各自的钠盐和上述物质的混合物；二乙胺与表氯醇的至少一种胺反应产物或异丁胺与表氯醇的胺反应产物或这些反应产物的混合物；至少一种乙二胺化合物,其选自以下群组：具有连接的EO-PO-嵌段聚合物的乙二胺化合物、具有连接的EO-PO-嵌段聚合物和磺基琥珀酸根基团的乙二胺化合物及其混合物；苄基氯与至少一种聚亚烷基亚胺的至少一种芳族反应产物,和使用所述电镀浴电解沉积酮涂层的方法。(An aqueous acidic copper electroplating bath comprising copper ions, at least acids, halide ions, at least sulfur-containing compounds selected from the group consisting of sodium 3-mercaptopropyl sulfonate, bis (sodiosulfopropyl) disulfide, 3- (N, N-dimethylthiocarbamoyl) -thiopropanesulfonic acid or its respective sodium salts and mixtures of the foregoing, at least amine reaction products of diethylamine with epichlorohydrin or amine reaction products of isobutylamine with epichlorohydrin or mixtures of these reaction products, at least ethylenediamine compounds selected from the group consisting of ethylenediamine compounds having linked EO-PO-block polymers, ethylenediamine compounds having linked EO-PO-block polymers and sulfosuccinate groups and mixtures thereof, at least aromatic reaction products of benzylchloride with at least polyalkyleneimines, and a method of electrolytically depositing a ketone coating using said electroplating bath.)

1. An aqueous acidic copper electroplating bath comprising:

-copper ions;

-at least acids;

-a halide ion;

-at least sulfur-containing compounds selected from the group consisting of sodium 3-mercaptopropyl sulfonate, bis (sodium sulfopropyl) disulfide, 3- (N, N-dimethylthiocarbamoyl) -thiopropanesulfonic acid or the respective sodium salts thereof and mixtures of the foregoing;

-at least amine reaction products of diethylamine with epichlorohydrin or amine reaction products of isobutylamine with epichlorohydrin or mixtures of these reaction products, wherein said at least amine reaction products of diethylamine with epichlorohydrin or isobutylamine with epichlorohydrin comprise a mixture of at least tertiary and/or quaternary ammonium compounds;

-at least ethylenediamine compounds selected from the group consisting of ethylenediamine compounds with attached EO-PO-block polymers, ethylenediamine compounds with attached EO-PO-block polymers and sulfosuccinate groups and mixtures thereof;

-at least aromatic reaction products of benzyl chloride with at least polyalkyleneimines wherein the at least aromatic reaction products comprise benzylated polyalkyleneimines or a plurality of benzylated polyalkyleneimines forming a mixture.

2. The electroplating bath according to claim 1, wherein the benzylated polyalkyleneimines or benzylated polyalkyleneimines of the mixture each have 2 or more nitrogen atoms, preferably 2 to 60 nitrogen atoms, more preferably 2 to 50 nitrogen atoms, even more preferably 5 to 40 nitrogen atoms.

3. The electroplating bath according to claim 1 or 2, wherein the mixture of benzylated polyalkyleneimines comprises benzylated polyalkyleneimines having benzylated amino groups, which are primary, secondary or tertiary amino groups benzylated with from 0 to 3 benzyl groups, and wherein the benzylated amino groups may be connected to each other by alkylene groups, with the proviso that at least amino groups are benzylated.

4. The electroplating bath of any of the foregoing claims, wherein the at least aromatic reaction products are aromatic reaction products of benzyl chloride and polyethyleneimine.

5. Electroplating bath according to any of the preceding claims, wherein the linked EO-PO-block polymer has a molecular weight of 500 to 7000 g/mol, and preferably the EO/PO ratio of the block polymer is 0.88.

6. The electroplating bath according to any of the preceding claims, wherein the bath further comprises at least inhibitor compounds selected from or more polyethylene glycols having a molecular weight of 1000 to 20000 g/mol, polypropylene glycols having a molecular weight of 400 to 2000g/mol and EO-PO copolymers having a molecular weight of 1000 to 10000 g/mol.

7. The electroplating bath of any of the preceding claims, wherein the at least amine reaction products of diethylamine with epichlorohydrin or isobutylamine with epichlorohydrin include quaternary ammonium compounds.

8. The electroplating bath of any of the foregoing claims, wherein the at least acids are selected from mineral acids, alkyl sulfonic acids, and mixtures thereof.

9. The electroplating bath of any of the preceding claims, wherein the bath has a pH of less than 1.

10. The electroplating bath according to any of the preceding claims, wherein the bath further comprises a source of Fe (II) ions at a concentration of 50 to 1000 mg/l.

11. The electroplating bath of any of the preceding claims, wherein the concentration of the at least amine reaction products in the bath is from 5 to 200 mg/L.

12. The electroplating bath of any of the preceding claims, wherein the concentration of the at least ethylenediamine compound in the bath is from 50 to 400 mg/L.

13. The electroplating bath of any of the preceding claims, wherein the concentration of the at least aromatic reaction products in the bath is 0.1 to 6 mg/L.

14. A method for the electrolytic deposition of a copper coating onto a substrate from an electroplating bath according to any of claims 1 to 13, the method comprising the sequential steps of:

-providing a substrate having a surface to be plated,

-contacting the substrate with the bath, and

-applying an electric current between the substrate and an anode, thereby depositing a copper coating onto the surface of the substrate.

Technical Field

The present invention relates to aqueous acidic copper electroplating baths for the electrolytic deposition of copper coatings and methods for the electrolytic deposition of copper coatings, especially bright and uniform copper coatings.

Background

Various methods and deposition solutions for copper plating are used to prepare decorative bright and flush surfaces, such as large surfaces, on metal or plastic materials. They are used in particular for forming ductile layers, for example in the field of decorative coatings for sanitary or automotive equipment, in which an intermediate copper layer is required for the subsequent deposition of different metal layers, for example for corrosion protection and/or decorative layers.

A uniform and shiny appearance is especially desirable for the final metal layer on the substrate surface. Uniformity of appearance can be easily achieved on a substrate without a complicated shape because the current density distribution during electroplating of a copper layer is in a narrow range.

Various additives, known as brighteners, levelers, surfactants, can be added, which are responsible for the deposit quality, for example in terms of brightness distribution and flat deposition, and also for the properties of the deposition bath in terms of the applicable current density and bath stability.

It has long been known to use certain dyes, such as phenazinium compounds and their derivatives, for the production of bright copper layers. These phenazinium compounds (described for example in DE 947656C 1) are used as additives in baths for the electrolytic production of copper coatings.

US 2008210569 a1 describes aqueous acidic solutions for the electrolytic deposition of copper deposits, which use polyvinylammonium compounds to produce decorative, shiny and flush surfaces.

The use of reaction products of polyalkanolamines with alkylating or quaternizing agents (U.S. Pat. No. 4,110,176) and reaction products of polyalkyleneimines with epichlorohydrin and alkylating agents (EP 0068807A 2) as additives in copper baths to produce bright and flush coatings is also described.

DE 19643091 A1 describes agents for treating metal or metallized surfaces, which agents contain water-soluble reaction products of water-soluble polyamideimides and/or polyimines with epichlorohydrin, and the use of the agents in copper, noble metal or alloy baths and processes for producing these agents, although the plating baths described allow well-distributed, ductile copper deposits to be achieved, the coatings show hardly any levelling and are therefore unsuitable for decorative purposes.

EP 1197587 a2 describes compositions comprising metal ions and a branched heteroatom-containing inhibitor compound. The composition can be used for repairing and electroplating the seed crystal layer.

US 4,336,114 describes compositions and methods for electrodepositing ductile, shiny, flush copper deposits from aqueous acidic copper plating electrolytes (particularly suitable for plating electronic circuit boards) containing a brightening and leveling amount of a brightening and leveling system comprising (a) a bath soluble substituted phthalocyanine group, (b) a bath soluble adduct of a tertiary alkylamine with polyepichlorohydrin, (c) a bath soluble organic divalent sulfur compound, and (d) a bath soluble reaction product of a polyethyleneimine and an alkylating agent that will alkylate the nitrogen on the polyethyleneimine to produce a quaternary nitrogen.

US 2,842,488 describes a process for preparing bright copper electrodeposits from an acidic copper electroplating bath comprising hard water, a technical grade copper salt and α -sulfonic acid brightener.

However, in the case where the substrate to be coated has a complicated shape or there is a small relief of a structure such as letters or symbols in the surface of the substrate to be plated, the flow of the electrolyte and the local current density on the surface during electroplating may vary in a wide range, resulting in plating defects. Typical substrates having a complex shape or surface (to be coated with a metal deposit) are, for example, automobile interior parts, front grills or emblems (having, for example, the relief of symbols or letters of the automobile manufacturer).

Additionally, the copper electrolytes described above do not allow for the use of the high current densities desired for electroplating.

Known methods and plating solutions for such substrates having complex shapes and/or structured surfaces are insufficient. Decorative shiny and conformal surfaces cannot be produced without undesirable effects such as overly flush structures, hydrodynamic defects, pits and nodules. Furthermore, when using the known solutions, good levelling properties cannot be achieved without impairing the shiny appearance of the surface layer and using higher current densities. Especially small structures with protrusions, grooves or increments of different depth show an undesired different copper growth, which results in a non-uniform surface appearance, wherein the coating will not follow the shape of the structure smoothly.

In addition, reproducible, particularly bright, i.e. mirror-polished, and well-leveled and ductile copper deposit qualities are generally not achievable.

Objects of the invention

The object of the present invention is therefore to avoid the disadvantages of the known copper baths and methods during the metallization of workpieces, such as metal or plastic substrates, and more particularly to provide additives which allow particularly bright and flush and ductile copper coatings to be produced reproducibly.

Another object of the invention is to enable the drawbacks of the prior art to be avoided and to provide an electroplating bath and a method for depositing copper.

Another objective of the invention is to make the available current density as high as possible to improve plating performance, while at the same time avoiding the effect of using higher current densities to build up uneven coatings on complex shapes and/or structured surfaces.

Disclosure of Invention

This object is solved by aqueous acidic copper electroplating baths comprising:

-copper ions;

-at least acids;

-a halide ion;

-at least sulfur-containing compounds selected from the group consisting of sodium 3-mercaptopropyl sulfonate, bis (sodium sulfopropyl) disulfide, 3- (N, N-dimethylthiocarbamoyl) -thiopropanesulfonic acid or the respective sodium salts thereof and mixtures of the foregoing;

-at least amine reaction products of diethylamine with epichlorohydrin or amine reaction products of isobutylamine with epichlorohydrin or mixtures of these reaction products, wherein said at least amine reaction products of diethylamine with epichlorohydrin or isobutylamine with epichlorohydrin comprise a mixture of at least tertiary and/or quaternary ammonium compounds;

-at least ethylenediamine compounds selected from the group consisting of ethylenediamine compounds with attached EO-PO-block polymers, ethylenediamine compounds with attached EO-PO-block polymers and sulfosuccinate groups and mixtures thereof;

-at least aromatic reaction products of benzyl chloride with at least polyalkyleneimines wherein the at least aromatic reaction products comprise benzylated polyalkyleneimines or a plurality of benzylated polyalkyleneimines forming a mixture.

The object is also solved by a method for the electrolytic deposition of a copper coating, in particular a bright and uniform copper coating, onto a substrate from an electroplating bath as described above, comprising the following sequential steps:

-providing a substrate having a surface to be plated,

-contacting the substrate with the bath, and

-applying an electric current between the substrate and an anode, thereby depositing a copper coating onto the surface of the substrate.

The electroplating baths of the present invention may advantageously be used for electrolytically producing bright, flush copper coatings on substrates for producing decorative and/or extensible surfaces of these substrates. For example, good levelling properties can be seen, since the copper coating does significantly reduce the visibility of defects from the substrate, for example from the plastic surface. The bath is particularly useful for decorative copper plating of plastic parts for the hygiene and automotive industry, particularly with complex shapes.

With the electroplating bath and method of the invention, a copper coating is obtained which has a bright and uniform appearance at step and at the same time is very conformal to the relief and structure in the substrate surface with complex shapes.

In addition, less propensity for calcination and copper buildup at the edges or in the surface relief of the substrate is observed, as well as less susceptibility to pitting and porosity. If higher leveling properties are required in addition to the still improved brightness of the coating, the concentrations of the following additives, amine reaction product, ethylenediamine compound and aromatic reaction product, can be adjusted at higher concentrations to provide a more flush coating, wherein hydrodynamic defects are simultaneously provided.

The term "complex shape" in relation to a substrate to be plated by the method according to the invention is defined herein in particular as a shape which, due to small reliefs and structures in the surface of the substrate, generates local turbulence during electroplating, thereby generating a strongly varying local mass transfer to the surface. In contrast, a substrate having, for example, a substantially flat plate-like shape such as a metal strip is not considered to be a substrate having a complex shape.

Combinations of different additives at different concentrations can be used to deposit a copper coating on the embossments and structures of the substrate to be plated at a reasonable plating time, but at the same time, for example, without excessive leveling of these embossments and structures.

Detailed Description

Preferred embodiments of the present invention are explained below, and also explained in more detail in the examples.

The aqueous acidic copper electroplating bath according to the invention is essentially free of dyes or dye-containing additives, respectively. This means that no dye or dye-containing additive, such as phenazine dyes, in particular no strongly dyeing dyes under visible light (VIS) conditions, is added to the electroplating bath, since dye-containing additives have the disadvantage of an undesirably strong levelling effect and also have a very strong colour, which can stain the surroundings of the electrolyte, the equipment and the plating bath.

In general, an aqueous acidic copper electroplating bath is used which has copper (II) ions, preferably in a concentration of from 20 to 300 g/l, more preferably from 120 to 270 g/l, at least acids, preferably in a concentration of from 50 to 350 g/l, more preferably from 50 to 150 g/l, and halide ions, preferably in a concentration of from 10 to 250 mg/l, more preferably from 40 to 160 mg/l, and a sulfur-containing compound selected from the group consisting of sodium 3-mercaptopropylsulfonate, bis (sodium sulfopropyl) disulfide (SPS), 3- (N, N-dimethylthiocarbamoyl) -mercaptopropanesulfonic acid, the respective sodium salts thereof and mixtures of the aforementioned substances is added to the electroplating bath according to the invention, preferably in a concentration of from 2 to 70 mg/l, more preferably from 5 to 50 mg/l.

As the copper ion source, copper (II) sulfate (CuSO) is preferably used₄×5H₂O). At least in part, other copper salts besides copper sulfate may be used.

The at least acids are preferably selected from the group consisting of mineral acids, alkyl sulfonic acids and mixtures thereof in a preferred embodiment, the at least acids are sulfuric and/or hydrochloric acid as mineral acids, which may also be partially replaced by methanesulfonic and/or propanesulfonic acid, the bath pH is preferably 1 or below 1.

As halide, chloride is preferably used and is preferably added as alkali metal chloride (e.g.sodium chloride) or as hydrochloric acid. If the compounds or reaction products of the electroplating bath according to the invention already contain halide ions, the addition of halide ions can be partly or completely omitted.

To complete and provide the electroplating bath according to the invention, other compounds and reaction products are added to the basic electroplating bath.

The concentration of the amine reaction product of diethylamine and epichlorohydrin in the plating bath and the concentration of the amine reaction product of isobutylamine and epichlorohydrin in the plating bath are 5 to 200 mg/l. If mixtures of amine reaction products are used, the total concentration of the mixture in the bath is from 5 to 200 mg/l.

According to the invention, the amine reaction product of diethylamine with epichlorohydrin or of isobutylamine with epichlorohydrin comprises a mixture of at least tertiary ammonium and/or quaternary ammonium compounds, more preferably both reaction products comprise quaternary ammonium compounds. In an even more preferred embodiment, the amine reaction product of diethylamine with epichlorohydrin is a product obtainable under CAS-number 88907-36-2, CAS-number 80848-16-4 or CAS-number 80848-02-8.

The at least polyalkyleneimines to be reacted with benzyl chloride preferably have 2 or more nitrogen atoms, preferably 2 to 60 nitrogen atoms, more preferably 2 to 50 nitrogen atoms, even more preferably 5 to 40 nitrogen atoms or 10 to 25 nitrogen atoms.

The polyalkyleneimines preferably have the general formula (I),

wherein m and n are integers, m is 1 to 2 and n > 2, preferably 2 to 60, more preferably 2 to 50, even more preferably 5 to 40 or 10 to 25.

The polyalkyleneimines used may be branched polyalkyleneimines or linear polyalkyleneimines or mixtures thereof. Linear polyalkyleneimines contain predominantly secondary amino groups. Branched polyalkyleneimines contain primary, secondary and tertiary amino groups. Preferably, the polyalkyleneimine is a polyethyleneimine or a polypropyleneimine.

In the present context, at least aromatic reaction products of benzyl chloride with polyalkyleneimines refers to the reaction product of benzyl chloride with or more polyalkyleneimines which results in benzylated polyalkyleneimines or a plurality of benzylated polyalkyleneimines forming a mixture, each of said benzylated polyalkyleneimines or benzylated polyalkyleneimines of said mixture having 2 or more nitrogen atoms, preferably 2 to 60 nitrogen atoms, more preferably 2 to 50 nitrogen atoms, even more preferably 5 to 40 nitrogen atoms or 10 to 25 nitrogen atoms.

In embodiments of the invention, the reaction of a mixture of polyalkyleneimines each having from 5 to 40 nitrogen atoms with benzyl chloride produces an aromatic reaction product comprising a plurality of benzylated polyalkyleneimines having nitrogen atoms (e.g., from 5 to 40 nitrogen atoms) forming the mixture.

Preferably, the benzylated polyalkyleneimine or mixture of benzylated polyalkyleneimines comprises a benzylated polyalkyleneimine having benzylated amino groups which are primary, secondary or tertiary amino groups benzylated with 0 to 3 benzyl groups and wherein the benzylated amino groups may be connected to each other by alkylene groups (also referred to in the art as alkanediyl) with the proviso that at least amino groups are benzylated.

Preferably, the polyethyleneimine has 2 to 60 nitrogen atoms, more preferably 2 to 50 nitrogen atoms, even more preferably 50 to 40 nitrogen atoms or 10 to 25 nitrogen atoms, more preferably, the polyethyleneimine has 2 to 60 nitrogen atoms, more preferably 2 to 50 nitrogen atoms, even more preferably 5 to 40 nitrogen atoms or 10 to 25 nitrogen atoms.

In a more preferred embodiment, the benzylated polyalkyleneimine is the product obtainable under CAS-number 68603-67-8.

The concentration of at least aromatic reaction products in the plating bath is 0.1 to 6mg/l, preferably 1 to 5 mg/l if a mixture of aromatic reaction products is used, the total concentration of the mixture in the plating bath is 1 to 5 mg/l.

In a preferred embodiment of the invention, the concentration of at least ethylenediamine compounds having only attached EO-PO-block polymers or having attached EO-PO-block polymers and sulfosuccinate groups, or mixtures thereof, in the electroplating bath is from 50 to 400 mg/l.

Preferably, the linked EO-PO-block polymer of the ethylenediamine compound has a molecular weight of 500 to 7000 g/mol, and preferably the EO/PO ratio of the block polymer is 0.88.

In another preferred embodiments, the ethylenediamine compound with attached EO-PO-block polymers and sulfosuccinate groups is a product obtainable under CAS number 26316-40-5sulf (sulf refers to sulfosuccinate).

If, in addition to the brightness of the coating still being improved, a higher leveling performance is required, the concentration of the additives amine reaction product, ethylenediamine compound and aromatic reaction product can be adjusted at higher concentrations to provide a more level coating, wherein the concentration of at least amine reaction products of diethylamine with epichlorohydrin is from 50 to 200mg/l, preferably from 50 to 150 mg/l, the concentration of at least ethylenediamine compounds is from 50 to 400 mg/l and the concentration of at least aromatic reaction products is from 0.1 to 6 mg/l.

In a preferred embodiment of the invention, the electroplating bath additionally comprises at least inhibitor compounds selected from or more polyethylene glycols having a molecular weight of 1000 to 20000 g/mol, preferably 3000 to 10000 g/mol, polypropylene glycols having a molecular weight of 400 to 2000g/mol and EO-PO copolymers (block or random) having a molecular weight of 1000 to 10000 g/mol, preferably 1000 to 1500 g/mol.

Preferred inhibitors that may be used alone or in combination are PEG-DME 2000, PEG 6000, PEG 10000 and PPG 900.

The inhibitor compound helps prevent or further reduce the formation of voids within the copper coating.

In a preferred embodiment of the invention, the electroplating bath additionally comprises Fe (II) ions in a concentration of 50 to 1000 mg/l. The addition of fe (ii) ions has a positive influence on the consumption of organic additives. The Fe (II) ions are preferably derived from water-soluble iron salts, e.g. FeSO₄x 7H₂O。

The present invention also provides a method for the electrolytic deposition of a copper coating onto a substrate from an electroplating bath according to the invention as described above, comprising the following sequential steps:

-providing a substrate having a surface to be plated,

-contacting the substrate with the electroplating bath, and

-applying an electric current between the substrate and an anode, thereby depositing a copper coating onto the surface of the substrate.

The operating conditions of the bath during deposition can preferably be adjusted as follows:

pH value: in the following description of the embodiments of the invention in <1,

temperature: the temperature of the mixture is between 15 and 45 ℃,

preferably from 20 c to 35 c,

cathode current density: 0.5 to 12A/dm²，

Preferably 2 to 6A/dm²。

Electrolyte movement (electrolyte movement) may be caused by electrolyte circulation, cathode movement and/or air blowing.

The following examples are intended to illustrate the invention and are not intended to be limiting:

general procedure:

plating experiments were conducted in a heler cell to simulate a wide range of local current densities on a substrate ("heler cell sheet") during electroplating. The substrate material was brass and had dimensions of 100mm x 75 mm.

The desired technical effect of improved brightness performance of the plating bath is determined by visual inspection of the brightness of the copper coating deposited over the entire Hull cell sheet, from the high local current density (HCD) point to the low Local Current Density (LCD) point of the Hull cell sheet, the HCD point is designated as the starting point from the left boundary of the Hull cell, from this point the current density on the Hull cell sheet is locally reduced stepwise to the LCD point at the right boundary of the Hull cell sheet, if no brightness change is observed over a length of 100mm in the direction of the LCD point, the distance from the left boundary to the right boundary of the Hull cell sheet refers to a value of 100%, if for example 90% of the distance in the direction of the LCD point is visually unchanged, the remaining 10% of the distance in the direction of the LCD point of the Hull cell sheet is visually reduced in brightness quality compared to the remaining 90%.

The brightness performance of the plating baths tested was determined by visual inspection of the heler bath sheets between the HCD and LCD spots, and the effect of the different additives alone or in combination was determined by comparing the sheets prepared using the base aqueous acidic copper electroplating bath with the different additives alone or in combination as explained in the examples.

The current applied at the left boundary of the hall slot die is 2A. The plating time was 10 minutes. The temperature of the bath was 25 ℃.

Basic aqueous acid copper electroplating:

CuSO₄×5 H₂O 220.0 g/l

sulfuric acid (96%, by weight) 70.0 g/l

NaCl 80.0 mg/l。

The indication of additive concentration in the examples refers to the final concentration of the plating bath.