Electroplating solution and use thereof, and electroplating method

Abstract

An electroplating solution and a use thereof, and an electroplating method, relating to the technical field of materials. The electroplating solution comprises a nickel salt, a grain refiner, a buffering agent, an auxiliary brightening agent, and a main brightening agent. The main brightening agent comprises an onium salt structure. The onium salt structure comprises an imidazole ring. The imidazole ring comprises onium ions, each onium ion is a positively charged organic ion and is composed of a nitrogen atom and three carbon atoms, and hydrogen on the nitrogen atom is substituted by alkyl, so that the alkylated onium ion structure has high adsorption capacity. The electroplating solution exhibits a high leveling effect, and can strongly adsorb on an uneven surface of a substrate to be electroplated, covering raised parts in the surface and filling recessed parts in the surface to form a uniform, low-roughness and glossy coating.

Description

An electroplating solution, an electroplating method and its application

[0001] This application claims priority to Chinese Patent Application No. 202410493984.5, filed on April 23, 2024, entitled “An Electroplating Solution, Electroplating Method and Its Application”, the entire contents of which are incorporated herein by reference. Technical Field

[0002] This application relates to the field of materials technology, and in particular to an electroplating solution, an electroplating method, and their applications. Background Technology

[0003] Nickel is a silvery-white metal with good ductility, malleability, and magnetism. It can be highly polished and has good corrosion resistance. Therefore, nickel has excellent decorative and functional properties and is one of the electroplating materials currently in use.

[0004] Typically, nickel plating solutions are prepared from nickel sulfate, nickel chloride, and boric acid. Furthermore, to achieve a bright and glossy appearance, organic and inorganic brighteners can be added. These brighteners are often added in combination to form a nickel plating layer with a certain gloss. However, when the substrate is a metal with a rough surface, such as die-cast aluminum, the aforementioned nickel plating solution cannot form a uniform and bright nickel plating layer with a limited thickness, exhibiting weak leveling ability. Summary of the Invention

[0005] This application provides an electroplating solution, an electroplating method, and its application. The electroplating solution has a high leveling effect and can strongly adsorb the uneven surface of the substrate to be electroplated, covering the raised parts of the surface and filling the surface depressions to form a uniform, low-roughness, and bright coating.

[0006] To achieve the above objectives, the embodiments of this application adopt the following technical solutions:

[0007] In a first aspect, embodiments of this application provide an electroplating solution, which includes: nickel salt, grain refiner, buffer, auxiliary brightener and main brightener;

[0008] The main brighteners include onium salts [A]. x [B] y ;

[0009] The general formula for the structure of A is as follows (1):

[0010] x and n are positive integers, and y is a natural number;

[0011] R1 is selected from C1-C4 alkyl groups;

[0012] When y = 0, R2 is selected from one of the following: hydrogen atom, unsaturated alkyl group containing double bond, aromatic hydrocarbon group, and heteroatom group.

[0013] When y≥1, R2 is selected from unsaturated alkyl groups containing double bonds;

[0014] B is selected from unsaturated monomers with at least one alkyl group.

[0015] Thus, the primary brightener in the electroplating solution provided in this application embodiment includes an onium salt. On one hand, the onium salt structure includes an imidazole ring, which contains an onium ion. An onium ion is a positively charged organic ion composed of one nitrogen atom and three carbon atoms, with the hydrogen atom on the nitrogen atom being substituted by an alkyl group. This alkylated onium ion structure possesses strong adsorption capacity, resulting in a strong adsorption capacity for the primary brightener. Therefore, one or more primary brighteners can be compounded with auxiliary brighteners to prepare the corresponding electroplating solution. When electroplating a substrate with high roughness, this electroplating solution can strongly adsorb onto the uneven surface of the substrate, covering the protruding parts and filling the depressions. This improves the leveling effect of the electroplating solution, resulting in a uniform, low-roughness, and bright coating.

[0016] On the other hand, the onium salt structure also includes R2 connected to an imidazole ring. R2 is selected from one of hydrogen atoms, unsaturated alkyl groups containing double bonds, aromatic hydrocarbon groups, and heteroatom groups. R2 can undergo addition polymerization with at least one unsaturated monomer with an alkyl group, which can improve the stability of the main brightener. At the same time, it can also promote the reaction between the main brightener and nickel salts, grain refiners, buffers, and auxiliary brighteners, thereby improving the dispersibility of the main brightener in the electroplating solution.

[0017] In one feasible embodiment, the double-bonded unsaturated alkyl group includes one of methenoyl, vinyl, and propenyl; the aromatic hydrocarbon group includes one of phenyl, phenolic, halophenyl, and tolyl; and the heteroatom group includes one of hydroxyl, amino, mercapto, carboxyl, and amide.

[0018] Thus, R2 provided in the embodiments of this application can be selected from the above-mentioned groups, and can undergo addition polymerization with unsaturated monomers of at least one alkyl group selected from the B structure, thereby forming a more stable onium salt structure and improving the stability of the main brightener.

[0019] In one feasible manner, the unsaturated monomer with at least one alkyl group comprises one of acrylamide, acryloylglycine, methacrylamide, N,N-dimethylacrylamide, acrylic acid, vinylformamide, vinylacetamide, vinylcaprolactam, vinylpyrrolidone, vinylimidazolium, vinylpyridine, vinylbenzoic acid, allylamine, N,N-dimethylallylamine, vinyl acetate, isopropyl acetate, aminoethyl methacrylate, and dimethylaminoethyl methacrylate.

[0020] Thus, the unsaturated monomer with at least one alkyl group provided in this application embodiment can be selected from the above-mentioned groups. Selecting these groups allows for addition polymerization with R2 in the main brightener structure, forming an onium salt structure with certain stability and dispersibility, thereby improving the stability of the main brightener. Simultaneously, when the main brightener is applied to the electroplating solution, the onium salt structure can more easily react with nickel salts, grain refiners, buffers, and auxiliary brighteners, improving the chemical properties of the electroplating solution.

[0021] In one feasible manner, the onium salt also includes anion selected from one of halogen-containing ions, hydrogen sulfate ions, and nitrate ions, including chloride ions, bromide ions, iodide ions, tetrafluoroborate ions, and hexafluorophosphate ions.

[0022] Therefore, the main brightener provided in this application embodiment may also include anion, which may be selected from the above-mentioned halogen-containing ions or halogen-free ions. This anion can react with positively charged onium ions, and the two combine to form an onium salt structure with certain stability and dispersibility. This improves the stability of the main brightener.

[0023] In one feasible approach, n is 1-5, x is 1-1000, and y is 0-1000.

[0024] Thus, by controlling the values ​​of n, x, and y in this embodiment, a tumium ion structure with strong adsorption, stability, and dispersion capabilities can be formed, resulting in a main brightener that also possesses strong adsorption, stability, and dispersion capabilities. Consequently, when this main brightener is subsequently applied to an electroplating solution, it can improve the leveling effect of the electroplating solution, forming a uniform, low-roughness, and bright coating on the surface of the substrate to be electroplated.

[0025] In one feasible method, the concentration of nickel salt in the electroplating solution is 1 g / L-500 g / L, the concentration of grain refiner is 0.1 g / L-10 g / L, the concentration of buffer is 1 g / L-100 g / L, the concentration of auxiliary brightener is 10 ppm-1000 ppm, and the concentration of at least one primary brightener is 0.5 ppm-50 ppm.

[0026] Thus, the embodiments of this application can control the concentration of nickel salt, grain refiner, buffer, auxiliary brightener and main brightener, so that the four are kept at a suitable concentration, which can form an electroplating solution with strong adsorption capacity, stability and dispersibility, so as to form a uniform, low roughness and bright coating on the surface of the substrate to be electroplated.

[0027] In one feasible manner, the structural formula of A includes at least one of the following structures:

[0028] Thus, the general structural formula corresponding to A in the onnnage salt provided in this application embodiment can include one of the structures in formulas (2) to (8) above. This structure includes an onnnage ion structure after alkylation, which enables the main brightener to have a strong adsorption capacity. At the same time, the above structure can undergo addition polymerization with at least one unsaturated monomer with an alkyl group, which facilitates the subsequent improvement of the stability of the main brightener. As a result, the leveling effect and stability of the electroplating solution are improved, so as to form a uniform, low-roughness and bright coating on the surface of the substrate to be electroplated.

[0029] In one feasible approach, the pH of the electroplating solution is 3-6.

[0030] In one feasible manner, the nickel salt includes at least one of nickel aminosulfonate, nickel chloride, nickel sulfate, and nickel acetate; the grain refiner includes one of sodium saccharin, thiourea and its derivatives, and coumarin and its derivatives; the buffer includes one of boric acid, citric acid, and acetic acid; and the auxiliary brightener includes one of pyridinium hydroxypropanesulfonate, pyridinium propanesulfonate, 1,4-butynediol, sodium propargyl sulfonate, sodium allyl sulfonate, ethoxybutynediol, and propargyl alcohol.

[0031] Secondly, embodiments of this application also provide an electroplating method for an electroplating solution, the method comprising: immersing a substrate to be electroplated into the electroplating solution described in the first aspect, and applying an electric current to the electroplating solution at a preset temperature to form an electroplating layer on the surface of the substrate to be electroplated.

[0032] Thus, the electroplating method provided in this application embodiment can form a thinner and smoother, brighter electroplated layer, achieving a smooth and glossy finish while providing substantial corrosion protection. Even if the roughness of the substrate to be electroplated is high, a mirror-like electroplated layer can still be formed.

[0033] In one feasible method, the current density is 0.1ASD-10ASD, the preset temperature is 40℃-65℃, and the thickness of the electroplated layer is less than 15μm.

[0034] Thirdly, embodiments of this application also provide the application of the electroplating solution described in the first aspect in electroplating metal casings, electroplating electronic device casings, and chip packaging. Attached Figure Description

[0035] Figure 1 is a schematic diagram of the coating appearance of Embodiment 1 provided in this application;

[0036] Figure 2 is a schematic diagram of the coating appearance of an embodiment 2 provided in this application;

[0037] Figure 3 is a schematic diagram of the coating appearance of Comparative Example 4 provided in the embodiments of this application;

[0038] Figure 4 is a schematic diagram of the coating appearance of Comparative Example 5 provided in the embodiments of this application. Detailed Implementation

[0039] The technical solutions of the embodiments of this application will be described below with reference to the accompanying drawings. In the description of this application, unless otherwise stated, " / " indicates that the objects before and after are in an "or" relationship. For example, A / B can represent A or B. "And / or" in this application is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A alone, A and B simultaneously, and B alone, where A and B can be singular or plural. Furthermore, in the description of this application, unless otherwise stated, "multiple" refers to two or more. "At least one of the following" or similar expressions refer to any combination of these items, including any combination of single or plural items. For example, at least one of a, b, or c can represent: a, b, c, ab, ac, bc, or abc, where a, b, and c can be single or multiple. In addition, in order to clearly describe the technical solutions of the embodiments of this application, the terms "first" and "second" are used in the embodiments of this application to distinguish the same or similar items with basically the same function and effect.

[0040] Those skilled in the art will understand that the terms "first," "second," etc., do not limit the quantity or order of execution, and that "first," "second," etc., are not necessarily different. Furthermore, in some embodiments of this application, words such as "exemplary" or "for example" are used to indicate that something is being described as an example, illustration, or description. Any embodiment or design scheme described as "exemplary" or "for example" in the embodiments of this application should not be construed as being more preferred or advantageous than other embodiments or design schemes. Specifically, the use of words such as "exemplary" or "for example" is intended to present the relevant concepts in a concrete manner for ease of understanding.

[0041] For ease of understanding, the examples provide explanations of some concepts related to the embodiments of this application for reference. As shown below:

[0042] Roughness Average (Ra): refers to the average surface roughness, which is the arithmetic mean of the absolute values ​​of the height deviations relative to the central plane of the area under investigation.

[0043] Leveling ability: also known as micro-dispersion ability, refers to the ability of the plating solution to make the micro-profile of the coating smoother than that of the substrate surface when forming a coating on a metal surface.

[0044] The nickel plating methods provided in related technologies include processes such as mechanical polishing, degreasing, chemical polishing, surface conditioning, zinc immersion, electroplating of a base nickel layer, electroplating of coke copper, electroplating of acid copper, and electroplating of bright nickel. Alternatively, the process may include stamping, grinding, mechanical polishing, electroplating of nickel, and chemical nickel plating. Or, the process may include polishing pretreatment, electroplating of copper, matte nickel plating, semi-bright nickel plating, and post-treatment. These various processes, through mechanical and chemical polishing, can reduce the roughness of the substrate before one or more electroplating treatments. However, these processes are relatively complex, increasing electroplating costs and reducing the product yield during the electroplating process.

[0045] Related technologies also provide an electroplating solution that may include a cationic polymer brightener, which is the reaction product of an imidazole compound and a diepoxide. However, this electroplating solution can only achieve plating within a wider range of current densities, such as on electrical connectors and lead frames. Thus, when using this electroplating solution to electroplat on substrates with high roughness, its leveling ability is low, which limits its application.

[0046] Related technologies also provide another electroplating solution that can provide a semi-bright nickel or nickel alloy electroplating bath without coumarin, with leveling characteristics close to or even equal to those of a coumarin bath. However, the plating layer formed by this electroplating solution has low internal stress, meaning that a bright plating layer can only be achieved under low internal stress conditions. Thus, when using this electroplating solution to electroplat on substrates with high roughness, its leveling ability is relatively low, which limits its application.

[0047] To address the aforementioned technical problems, embodiments of this application provide an electroplating solution comprising: nickel salt, grain refiner, buffer, auxiliary brightener, and main brightener, wherein the main brightener comprises onium salt [A]. x [B] y .

[0048] The general structural formula of A is given by equation (1):

[0049] x and n are positive integers, and y is a natural number;

[0050] R1 is selected from C1-C4 alkyl groups;

[0051] When y = 0, R2 is selected from one of the following: hydrogen atom, unsaturated alkyl group containing double bond, aromatic hydrocarbon group, and heteroatom group;

[0052] When y≥1, R2 is selected from unsaturated alkyl groups containing double bonds;

[0053] B is selected from unsaturated monomers with at least one alkyl group.

[0054] Thus, the primary brightener in the electroplating solution provided in this application includes an onium salt. On one hand, the onium salt structure includes an imidazole ring, which contains an onium ion. An onium ion is a positively charged organic ion composed of one nitrogen atom and three carbon atoms, with the hydrogen atom on the nitrogen atom being substituted by an alkyl group. This alkylated onium ion structure possesses strong adsorption capacity, resulting in a strong adsorption capacity for the primary brightener. Therefore, one or more primary brighteners can be compounded with auxiliary brighteners to prepare the corresponding electroplating solution. When electroplating a substrate with high roughness, this electroplating solution can strongly adsorb onto the uneven surface of the substrate, covering the protruding parts and filling the surface depressions. This improves the leveling effect of the electroplating solution, resulting in a uniform, low-roughness, and bright coating.

[0055] On the other hand, the onium salt structure also includes R2 connected to an imidazole ring. R2 is selected from one of hydrogen atoms, unsaturated alkyl groups containing double bonds, aromatic hydrocarbon groups, and heteroatom groups. R2 can undergo addition polymerization with at least one unsaturated monomer with an alkyl group, which can improve the stability of the main brightener. At the same time, it can also promote the reaction between the main brightener and nickel salts, grain refiners, buffers, and auxiliary brighteners, thereby improving the dispersibility of the main brightener in the electroplating solution.

[0056] It should be noted that the main brightener of the electroplating solution in the embodiments of this application can be one type of main brightener having the above-mentioned general structural formula. Of course, it can also be a variety of different main brighteners having the above-mentioned general structural formula. The embodiments of this application do not specifically limit this.

[0057] In some embodiments of this application, the unsaturated alkyl group containing a double bond includes one of methenoyl, vinyl and propenyl, the aromatic hydrocarbon group includes one of phenyl, phenolic, halophenyl and tolyl, and the heteroatom group includes one of hydroxyl, amino, mercapto, carboxyl and amide.

[0058] In some examples, R2 may be selected from the unsaturated alkyl groups containing double bonds, including one of methanyl, vinyl, and propenyl. Of course, it may also include butenyl, pentenyl, hexenyl, and styryl, etc. It should be noted that the embodiments of this application do not specifically limit the groups selected from the unsaturated alkyl groups containing double bonds.

[0059] In some examples, the aromatic hydrocarbon group selected by R2 may include one of phenyl, phenolic, halophenyl, and tolyl. Of course, it may also include nitrophenyl, ethylphenyl, propanylphenyl, and butylphenyl, etc. It should be noted that the embodiments of this application do not specifically limit the groups selected from the aromatic hydrocarbon group.

[0060] In some examples, R2 is selected from one of the heteroatomic groups: hydroxyl, amino, mercapto, carboxyl, and amide. Of course, it may also include anhydride and ester groups, etc. It should be noted that the embodiments of this application do not specifically limit the groups selected from the heteroatomic groups.

[0061] Thus, R2 provided in the embodiments of this application can be selected from the above-mentioned groups, and can undergo addition polymerization with unsaturated monomers of at least one alkyl group selected from the B structure, thereby forming a more stable onium salt structure and improving the stability of the main brightener.

[0062] In some embodiments of this application, the unsaturated monomer with at least one alkyl group may include one of acrylamide, acryloylglycine, methacrylamide, N,N-dimethylacrylamide, acrylic acid, vinylformamide, vinylacetamide, vinylcaprolactam, vinylpyrrolidone, vinylimidazolium, vinylpyridine, vinylbenzoic acid, allylamine, N,N-dimethylallylamine, vinyl acetate, isopropyl acetate, aminoethyl methacrylate, and dimethylaminoethyl methacrylate. It should be noted that the embodiments of this application do not specifically limit the groups selected from the unsaturated monomer with at least one alkyl group.

[0063] Thus, the unsaturated monomer with at least one alkyl group provided in this application embodiment can be selected from the above-mentioned groups. Selecting these groups allows for addition polymerization with R2 in the main brightener structure, forming an onium salt structure with certain stability and dispersibility, thereby improving the stability of the main brightener. Simultaneously, when the main brightener is applied to the electroplating solution, the onium salt structure can more easily react with nickel salts, grain refiners, buffers, and auxiliary brighteners, improving the chemical properties of the electroplating solution.

[0064] In some embodiments of this application, the onium salt further includes anion selected from one of halogen-containing ions, hydrogen sulfate ions, and nitrate ions, wherein the halogen-containing ions include chloride ions, bromide ions, iodide ions, tetrafluoroborate ions, and hexafluorophosphate ions.

[0065] In some examples, the main brightener may also include anions selected from halogen-containing ions, such as chloride ions, bromide ions, iodide ions, tetrafluoroborate ions, and hexafluorophosphate ions. Anions may also be selected from hydrogen sulfate ions and nitrate ions. Of course, anions may also be selected from hydroxide ions, permanganate ions, chlorate ions, iodate ions, and formate ions, etc. It should be noted that the embodiments of this application do not specifically limit the selected anions.

[0066] Therefore, the main brightener provided in this application embodiment may also include anion, which may be selected from the above-mentioned halogen-containing ions or halogen-free ions. This anion can react with positively charged onium ions, and the two combine to form an onium salt structure with certain stability and dispersibility. This improves the stability of the main brightener.

[0067] In some embodiments of this application, n is 1-5, x is 1-1000, and y is 0-1000.

[0068] In some examples, the value of n is typically, but not limited to, for example, 1, 2, 3, 4, and 5.

[0069] In some examples, the value of x can typically, but not exclusively, be 1, 3, 10, 50, 200, 300, 650, 800, 1000, or any number between any two of the above values. These are all possible values. For example, the value can be a number between 1 and 100, or between 100 and 500, or between 500 and 700, or between 700 and 1000, or any other number between any two values.

[0070] In some examples, the value of y can typically, but not exclusively, be 0, 1, 5, 15, 55, 250, 350, 650, 850, 1000, or any number between any two of the above values. These are all possible values. For example, the value can be a number between 0 and 50, or between 50 and 200, or between 200 and 500, or between 500 and 1000, or any other number between any two values.

[0071] Thus, by controlling the values ​​of n, x, and y in this embodiment, a tumium ion structure with strong adsorption, stability, and dispersion capabilities can be formed, resulting in a main brightener that also possesses strong adsorption, stability, and dispersion capabilities. Consequently, when this main brightener is subsequently applied to an electroplating solution, it can improve the leveling effect of the electroplating solution, forming a uniform, low-roughness, and bright coating on the surface of the substrate to be electroplated.

[0072] In some embodiments of this application, the concentration of nickel salt in the electroplating solution is 1 g / L-500 g / L, the concentration of grain refiner is 0.1 g / L-10 g / L, the concentration of buffer is 1 g / L-100 g / L, the concentration of auxiliary brightener is 10 ppm-1000 ppm, and the concentration of at least one main brightener is 0.5 ppm-50 ppm.

[0073] In some examples, the concentration of nickel salt in the electroplating solution can typically, but not be limited to, being 1 g / L, 5 g / L, 15 g / L, 35 g / L, 100 g / L, 150 g / L, 250 g / L, 350 g / L, 500 g / L, or any value between any two of the above. These are all acceptable ranges. For example, the value can be taken from 1 g / L to 100 g / L, from 100 g / L to 150 g / L, from 150 g / L to 350 g / L, from 350 g / L to 500 g / L, or any other value between any two of the above.

[0074] In some examples, the concentration of the grain refiner in the electroplating solution can typically, but not limited to, be 0.1 g / L, 0.5 g / L, 1.5 g / L, 3.5 g / L, 5.5 g / L, 6.5 g / L, 7.5 g / L, 8.5 g / L, 10 g / L, or any value between any two of the above. These are all acceptable ranges. For example, the value can be taken from a range between 0.1 g / L and 3.5 g / L, or between 3.5 g / L and 5.5 g / L, or between 5.5 g / L and 8.5 g / L, or between 8.5 g / L and 10 g / L, or any other value between any two of the above.

[0075] In some examples, the concentration of the buffer in the electroplating solution can typically, but not limited to, be 1 g / L, 5 g / L, 15 g / L, 35 g / L, 100 g / L, or any number between any two of the above values. These are all acceptable ranges. For example, the value can be between 1 g / L and 10 g / L, between 10 g / L and 25 g / L, between 25 g / L and 50 g / L, between 50 g / L and 100 g / L, or any other number between any two values.

[0076] In some examples, the concentration of the auxiliary brightener in the electroplating solution is typically, but not limited to, 10 ppm, 20 ppm, 50 ppm, 100 ppm, 500 ppm, 750 ppm, 850 ppm, 1000 ppm, and any number between any two of the above values. These are all acceptable ranges. For example, the value can be between 10 ppm and 100 ppm, between 100 ppm and 200 ppm, between 200 ppm and 500 ppm, between 500 ppm and 1000 ppm, or any other number between any two values.

[0077] In some examples, the concentration of at least one primary brightener in the electroplating solution can typically, but not limited to, be 0.5 ppm, 1 ppm, 2 ppm, 10 ppm, 20 ppm, 30 ppm, 35 ppm, 50 ppm, or any number between any two of the above values. These are all possible ranges, for example, the value can be between 0.5 ppm and 1 ppm, between 1 ppm and 2 ppm, between 10 ppm and 30 ppm, between 30 ppm and 50 ppm, or any other number between any two values.

[0078] Thus, the embodiments of this application can control the concentration of nickel salt, grain refiner, buffer, auxiliary brightener and main brightener, so that the four are kept at a suitable concentration, which can form an electroplating solution with strong adsorption capacity, stability and dispersibility, so as to form a uniform, low roughness and bright coating on the surface of the substrate to be electroplated.

[0079] It should be noted that the electroplating solution provided in this application embodiment may contain other unavoidable trace impurities, which are not limited in this application embodiment.

[0080] In some embodiments of this application, the general formula of A includes at least one of the following structures:

[0081] In Equation (6), a accounts for 5%-80% of the entire structure; in Equation (7), a accounts for 5%-80% of the entire structure; and in Equation (8), a accounts for 5%-80% of the entire structure.

[0082] In some examples, the values ​​corresponding to the proportion of 'a' in the whole structure in equations (6)-(8) above can typically, but not limitedly, be 5%, 15%, 25%, 35%, 45%, 55%, 65%, 75%, 85%, and any number between any two of the above values. These are all possible values. For example, the numerical ratio can be taken from a value between 5% and 20%, or between 20% and 35%, or between 35% and 50%, or between 50% and 86%, or any other number between any two values.

[0083] Thus, the general structural formula corresponding to A in the onnnage salt provided in this application embodiment can include one of the structures in formulas (2) to (8) above. This structure includes an onnnage ion structure after alkylation, which enables the main brightener to have a strong adsorption capacity. At the same time, the above structure can undergo addition polymerization with at least one unsaturated monomer with an alkyl group, which facilitates the subsequent improvement of the stability of the main brightener. As a result, the leveling effect and stability of the electroplating solution are improved, so as to form a uniform, low-roughness and bright coating on the surface of the substrate to be electroplated.

[0084] In some embodiments of this application, the pH of the electroplating solution provided in this application embodiment can be 3-6.

[0085] In some embodiments of this application, the nickel salt provided may include at least one of nickel sulfamate, nickel chloride, nickel sulfate, and nickel acetate. It should be noted that this application does not limit the specific material used to implement the nickel salt.

[0086] In some embodiments of this application, the grain refiner provided may include one of sodium saccharin, thiourea and its derivatives, and coumarin and its derivatives. It should be noted that this application does not limit the specific material used to implement the grain refiner.

[0087] In some embodiments of this application, the buffer provided may include one of boric acid, citric acid, and acetic acid. It should be noted that this application does not limit the specific material used to implement the buffer.

[0088] In some embodiments of this application, the auxiliary brightener provided may include one of the following: pyridinium hydroxypropanesulfonate, pyridinium propanesulfonate, 1,4-butynediol, sodium propargyl sulfonate, sodium allyl sulfonate, ethoxybutynediol, and propargyl alcohol. It should be noted that the embodiments of this application do not limit the specific material used to implement the auxiliary brightener.

[0089] This application embodiment also provides a method for preparing an electroplating solution, the method comprising: weighing an appropriate mass of nickel salt and buffer according to the above concentration and preparing a mixed solution with water; after fully dissolving, sequentially adding a grain refiner, an auxiliary brightener and a main brightener to the mixed solution and mixing them evenly so that the corresponding concentrations reach the above concentration range, thereby preparing the electroplating solution.

[0090] It is understood that in the process of preparing electroplating solution using nickel salt, grain refiner, buffer, auxiliary brightener and main brightener, a certain measurement and testing error is allowed. Values ​​within the error range can be understood as the range defined by the embodiments of this application.

[0091] This application also provides an electroplating method using an electroplating solution, the method comprising: immersing a substrate to be electroplated into the electroplating solution prepared above. Applying an electric current to the electroplating solution at a preset temperature to form an electroplated layer on the surface of the substrate. The current density is 0.1 ASD-10 ASD, the preset temperature is 40℃-65℃, and the thickness of the electroplated layer is less than 15 μm. Further, the thickness of the electroplated layer is less than 12 μm.

[0092] In some embodiments, the substrate to be electroplated may include aluminum or aluminum alloy, copper or copper alloy, or magnesium or magnesium alloy. It should be noted that the embodiments of this application do not limit the material corresponding to the substrate to be electroplated.

[0093] Thus, by using the electroplating method of this application embodiment and electroplating with the electroplating solution prepared above, a thinner and smoother electroplating layer can be formed to achieve a smooth and bright finish and provide a large amount of corrosion protection.

[0094] The above electroplating solution is described in Table 1 below through specific examples. The electroplating solution prepared in the examples is used to electroplat the substrate to be electroplated, and the performance of the substrate before and after electroplating is tested.

[0095] In some embodiments of this application, nickel sulfamate, nickel chloride, and boric acid are mixed with water to prepare a mixed solution of 300 g / L nickel sulfamate, 20 g / L nickel chloride, and 45 g / L boric acid. After complete dissolution, sodium saccharin is added to the mixed solution to achieve a concentration of 0.5 g / L, then a first onium chloride salt is added to achieve a concentration of 5 ppm, and pyridinium hydroxypropanesulfonate salt is added to achieve a concentration of 100 ppm. The solution is stirred continuously for 10 minutes to ensure uniform mixing, thus preparing the electroplating solution (referred to as Example 1). The A structure in the first onium chloride salt is 1-(2-hydroxyethyl)-3-methylimidazolium (Formula 2 above).

[0096] The prepared electroplating solution was then adjusted to pH 4.2 using ammonia and transferred to a 1.5L Haring bath. The substrate to be electroplated was then immersed in the electroplating solution in the Haring bath. The electroplating solution was heated to 55 degrees Celsius, and electroplating was performed for 70 minutes using a titanium plate as the anode and an aluminum plate as the cathode, with a current of 1.0 ASD, to form an electroplated layer on the surface of the substrate.

[0097] Thus, after the electroplating is completed, the thickness of the electroplated layer can be measured to be 9.8 μm using a film thickness gauge. The roughness Ra of the aluminum plate before electroplating is 1.752 μm, and the Ra after electroplating is 0.309 μm, with a leveling effect of 82.36%. The electroplated layer has a mirror-like gloss.

[0098] In some embodiments of this application, nickel sulfamate, nickel chloride, and boric acid are mixed with water to prepare a mixed solution of 300 g / L nickel sulfamate, 20 g / L nickel chloride, and 45 g / L boric acid. After complete dissolution, sodium saccharin is added to the mixed solution to achieve a concentration of 0.5 g / L, then a second onium chloride salt is added to achieve a concentration of 5 ppm, and finally, pyridinium hydroxypropanesulfonate salt is added to achieve a concentration of 100 ppm. The solution is stirred continuously for 10 minutes to ensure uniform mixing, thus preparing the electroplating solution (referred to as Example 2). The A structure in the second onium chloride salt is 1-allyl-3-methylimidazolium chloride (Formula 3 above).

[0099] The prepared electroplating solution was then adjusted to pH 4.2 using ammonia and transferred to a 1.5L Haring bath. The substrate to be electroplated was then immersed in the electroplating solution in the Haring bath. The electroplating solution was heated to 55 degrees Celsius, and electroplating was performed for 70 minutes using a titanium plate as the anode and an aluminum plate as the cathode, with a current of 1.0 ASD, to form an electroplated layer on the surface of the substrate.

[0100] Thus, after the electroplating is completed, the thickness of the electroplated layer can be measured to be 11.0 μm using a film thickness gauge. The roughness Ra of the aluminum plate before electroplating is 1.336 μm, and the Ra after electroplating is 0.468 μm, with a leveling effect of 64.97%. The electroplated layer has a mirror-like gloss.

[0101] In some embodiments of this application, nickel sulfamate, nickel chloride, and boric acid are mixed with water to prepare a mixed solution of 300 g / L nickel sulfamate, 20 g / L nickel chloride, and 45 g / L boric acid. After complete dissolution, sodium saccharin is added to the mixed solution to achieve a concentration of 0.5 g / L, then a third onium chloride salt is added to achieve a concentration of 10 ppm, and finally, pyridinium hydroxypropanesulfonate salt is added to achieve a concentration of 100 ppm. The solution is stirred continuously for 10 minutes to ensure uniform mixing, thus preparing the electroplating solution (referred to as Example 3). The A structure in the third onium chloride salt is a copolymer of quaternized vinylimidazolium and vinylpyrrolidone (Formula 6 above).

[0102] The prepared electroplating solution was then adjusted to pH 4.2 using ammonia and transferred to a 1.5L Haring bath. The substrate to be electroplated was then immersed in the electroplating solution in the Haring bath. The electroplating solution was heated to 55 degrees Celsius, and electroplating was performed for 70 minutes using a titanium plate as the anode and an aluminum plate as the cathode, with a current of 1.0 ASD, to form an electroplated layer on the surface of the substrate.

[0103] Thus, after the electroplating is completed, the thickness of the electroplated layer can be measured to be 13.5 μm using a film thickness gauge. The roughness Ra of the aluminum plate before electroplating is 1.472 μm, and the Ra after electroplating is 0.377 μm, with a leveling effect of 74.39%. The electroplated layer has a mirror-like gloss.

[0104] In some embodiments of this application, nickel sulfamate, nickel chloride, and boric acid are mixed with water to prepare a mixed solution of 300 g / L nickel sulfamate, 20 g / L nickel chloride, and 45 g / L boric acid. After complete dissolution, sodium saccharin is added to the mixed solution to achieve a concentration of 0.5 g / L, then a fourth onium chloride salt is added to achieve a concentration of 5 ppm, and pyridinium hydroxypropanesulfonate salt is added to achieve a concentration of 100 ppm. The solution is stirred continuously for 10 minutes to ensure uniform mixing, thus preparing the electroplating solution (referred to as Example 4). The A structure in the fourth onium chloride salt is 1-benzyl-3-methylimidazolium, and its concentration is (as described in Formula 5 above).

[0105] The prepared electroplating solution was then adjusted to pH 4.2 using ammonia and transferred to a 1.5L Haring bath. The substrate to be electroplated was then immersed in the electroplating solution in the Haring bath. The electroplating solution was heated to 55 degrees Celsius, and electroplating was performed for 70 minutes using a titanium plate as the anode and an aluminum plate as the cathode, with a current of 1.0 ASD, to form an electroplated layer on the surface of the substrate.

[0106] Thus, after the electroplating is completed, the thickness of the electroplated layer can be measured to be 10.4 μm using a film thickness gauge. The roughness Ra of the aluminum plate before electroplating is 1.225 μm, and after electroplating, Ra is 0.245 μm, with a leveling effect of 80.00%. The electroplated layer has a mirror-like glossy appearance.

[0107] In some embodiments of this application, nickel sulfamate, nickel chloride, and boric acid are mixed with water to prepare a mixed solution of 300 g / L nickel sulfamate, 20 g / L nickel chloride, and 45 g / L boric acid. After complete dissolution, sodium saccharin is added to the mixed solution to achieve a concentration of 0.5 g / L, then a fifth onium chloride salt is added to achieve a concentration of 10 ppm, and pyridinium hydroxypropanesulfonate salt is added to achieve a concentration of 100 ppm. The solution is stirred continuously for 10 minutes to ensure uniform mixing, thus preparing the electroplating solution (referred to as Example 5). The A structure in the fifth onium chloride salt is 1-butyl-3-methylimidazolium (Formula 4 above).

[0108] The prepared electroplating solution was then adjusted to pH 4.2 using ammonia and transferred to a 1.5L Haring bath. The substrate to be electroplated was then immersed in the electroplating solution in the Haring bath. The electroplating solution was heated to 55 degrees Celsius, and electroplating was performed for 70 minutes using a titanium plate as the anode and an aluminum plate as the cathode, with a current of 1.0 ASD, to form an electroplated layer on the surface of the substrate.

[0109] Thus, after the electroplating is completed, the thickness of the electroplated layer can be measured to be 12.8 μm using a film thickness gauge. The roughness Ra of the aluminum plate before electroplating is 1.564 μm, and after electroplating, Ra is 0.403 μm, with a leveling effect of 74.23%. The electroplated layer exhibits a mirror-like gloss.

[0110] In some embodiments of this application, nickel sulfamate, nickel chloride, and boric acid are mixed with water to prepare a mixed solution of 300 g / L nickel sulfamate, 20 g / L nickel chloride, and 45 g / L boric acid. After complete dissolution, sodium saccharin is added to the mixed solution to achieve a concentration of 0.5 g / L, and then pyridinium hydroxypropanesulfonate is added to achieve a concentration of 100 ppm. The solution is stirred continuously for 10 minutes to ensure uniform mixing, thus preparing the electroplating solution (referred to as Comparative Example 1).

[0111] The prepared electroplating solution was then adjusted to pH 4.2 using ammonia and transferred to a 1.5L Haring bath. The substrate to be electroplated was then immersed in the electroplating solution in the Haring bath. The electroplating solution was heated to 55 degrees Celsius, and electroplating was performed for 70 minutes using a titanium plate as the anode and an aluminum plate as the cathode, with a current of 1.0 ASD, to form an electroplated layer on the surface of the substrate.

[0112] Thus, after the electroplating is completed, the thickness of the electroplated layer can be measured to be 12.0 μm using a film thickness gauge. The roughness Ra of the aluminum plate before electroplating is 1.318 μm, and the Ra after electroplating is 0.719 μm, with a leveling effect of 45.45%, and the electroplated layer has a matte appearance.

[0113] In some embodiments of this application, nickel sulfamate, nickel chloride, and boric acid are mixed with water to prepare a mixed solution of 300 g / L nickel sulfamate, 20 g / L nickel chloride, and 45 g / L boric acid. After complete dissolution, sodium saccharin is added to the mixed solution to achieve a concentration of 0.5 g / L, and then 1-(2-hydroxyethyl)-3-methylimidazolium is added to achieve a concentration of 5 ppm. The solution is stirred continuously for 10 minutes to ensure uniform mixing, thus preparing the electroplating solution (referred to as Comparative Example 2).

[0114] The prepared electroplating solution was then adjusted to pH 4.2 using ammonia and transferred to a 1.5L Haring bath. The substrate to be electroplated was then immersed in the electroplating solution in the Haring bath. The electroplating solution was heated to 55 degrees Celsius, and electroplating was performed for 70 minutes using a titanium plate as the anode and an aluminum plate as the cathode, with a current of 1.0 ASD, to form an electroplated layer on the surface of the substrate.

[0115] Thus, after the electroplating is completed, the thickness of the electroplated layer can be measured to be 13.8 μm using a film thickness gauge. The roughness Ra of the aluminum plate before electroplating is 1.395 μm, and the Ra after electroplating is 0.903 μm, with a leveling effect of 35.27%. The electroplated layer has a rough and dull appearance.

[0116] In some embodiments of this application, nickel sulfamate, nickel chloride, and boric acid are mixed with water to prepare a mixed solution of 300 g / L nickel sulfamate, 20 g / L nickel chloride, and 45 g / L boric acid. After complete dissolution, sodium saccharin is added to the mixed solution to achieve a concentration of 0.5 g / L, then 1-(2-hydroxyethyl)-3-methylimidazolium is added to achieve a concentration of 100 ppm, and finally pyridinium hydroxypropanesulfonate is added to achieve a concentration of 100 ppm. The solution is stirred continuously for 10 minutes to ensure uniform mixing, thus preparing the electroplating solution (referred to as Comparative Example 3).

[0117] The prepared electroplating solution was then adjusted to pH 4.2 using ammonia and transferred to a 1.5L Haring bath. The substrate to be electroplated was then immersed in the electroplating solution in the Haring bath. The electroplating solution was heated to 55 degrees Celsius, and electroplating was performed for 70 minutes using a titanium plate as the anode and an aluminum plate as the cathode, with a current of 1.0 ASD, to form an electroplated layer on the surface of the substrate.

[0118] Thus, after the electroplating is completed, the thickness of the electroplated layer can be measured to be 12.2 μm using a film thickness gauge. The roughness Ra of the aluminum plate before electroplating is 1.531 μm, and the Ra after electroplating is 0.934 μm, with a leveling effect of 38.99%. The electroplated layer has a rough and dull appearance.

[0119] In some embodiments of this application, nickel sulfamate, nickel chloride, and boric acid are mixed with water to prepare a mixed solution of 300 g / L nickel sulfamate, 20 g / L nickel chloride, and 45 g / L boric acid. After complete dissolution, sodium saccharin is added to the mixed solution to achieve a concentration of 0.5 g / L, then imidazole-epoxychloropropane copolymer is added to achieve a concentration of 10 ppm, and pyridinium hydroxypropanesulfonate is added to achieve a concentration of 100 ppm. The solution is stirred continuously for 10 minutes to ensure uniform mixing, thus preparing the electroplating solution (referred to as Comparative Example 4).

[0120] The prepared electroplating solution was then adjusted to pH 4.2 using ammonia and transferred to a 1.5L Haring bath. The substrate to be electroplated was then immersed in the electroplating solution in the Haring bath. The electroplating solution was heated to 55 degrees Celsius, and electroplating was performed for 70 minutes using a titanium plate as the anode and an aluminum plate as the cathode, with a current of 1.0 ASD, to form an electroplated layer on the surface of the substrate.

[0121] Thus, after the electroplating is completed, the thickness of the electroplated layer can be measured to be 10.3 μm using a film thickness gauge. The roughness Ra of the aluminum plate before electroplating is 1.369 μm, and the Ra after electroplating is 0.804 μm, with a leveling effect of 41.27%. The electroplated layer has a matte appearance.

[0122] In some embodiments of this application, nickel sulfamate, nickel chloride, and boric acid are mixed with water to prepare a mixed solution of 300 g / L nickel sulfamate, 20 g / L nickel chloride, and 45 g / L boric acid. After complete dissolution, sodium saccharin is added to the mixed solution to achieve a concentration of 0.5 g / L, then 1-benzylpyridine-3-carboxylate is added to achieve a concentration of 5 ppm, and pyridine hydroxypropanesulfonate is added to achieve a concentration of 100 ppm. The solution is stirred continuously for 10 minutes to ensure uniform mixing, thus preparing the electroplating solution (referred to as Comparative Example 4).

[0123] The prepared electroplating solution was then adjusted to pH 4.2 using ammonia and transferred to a 1.5L Haring bath. The substrate to be electroplated was then immersed in the electroplating solution in the Haring bath. The electroplating solution was heated to 55 degrees Celsius, and electroplating was performed for 70 minutes using a titanium plate as the anode and an aluminum plate as the cathode, with a current of 1.0 ASD, to form an electroplated layer on the surface of the substrate.

[0124] Thus, after the electroplating is completed, the thickness of the electroplated layer can be measured to be 10.6 μm using a film thickness gauge. The roughness Ra of the aluminum plate before electroplating is 1.575 μm, and the Ra after electroplating is 0.705 μm, with a leveling effect of 55.24%. The electroplated layer has a matte appearance.

[0125] Table 1

[0126] Based on the above test results, Examples 1-5 exhibit strong leveling capabilities, and all show a mirror-like glossy finish. Specifically, referring to Figure 1, the electroplated layer of Example 1 has a mirror-like glossy finish. Referring to Figure 2, the electroplated layer of Example 2 also has a mirror-like glossy finish. The leveling effect achieved after electroplating using the electroplating solution provided in this application can reach over 60%. In Comparative Example 1, no main brightener was added, resulting in lower leveling capabilities and a matte finish. In Comparative Example 2, no auxiliary brightener was added, resulting in lower leveling capabilities and a dull finish. In Comparative Example 3, a higher concentration of main brightener was added, resulting in lower leveling capabilities and a dull finish. The brighteners used in Comparative Examples 4 and 5 were not the main brighteners provided in this application, leading to lower leveling capabilities. Specifically, referring to Figure 3, the electroplated layer of Comparative Example 4 has a matte finish. Referring to Figure 4, the electroplated layer corresponding to Comparative Example 5 also has a matte finish.

[0127] Thus, the electroplating solution provided in this application embodiment has a strong leveling ability, and after electroplating with the electroplating solution provided in this application embodiment, its appearance can present a good mirror gloss effect.

[0128] This application also provides the application of the above-mentioned electroplating solution in electroplating metal casings, electroplating electronic device casings, and chip packaging. For example, electroplating mobile phone metal casings, electroplating optical module casings, and electroplating computer metal casings. Of course, the electroplating solution provided in this application can also be used in automotive, electrical, appliance, hardware, and other industries to achieve a smooth, bright finish and provide substantial corrosion protection. The electroplating solution provided in this application is also suitable for deposition on various types of substrates to be electroplated.

[0129] In some solutions, multiple embodiments of this application can be combined, and the combined solution can be implemented. Optionally, some operations in the processes of each method embodiment may be combined, and / or the order of some operations may be changed. Furthermore, the execution order between the steps of each process is merely exemplary and does not constitute a limitation on the execution order between steps; other execution orders are also possible. It is not intended to indicate that the execution order is the only possible order in which these operations can be performed.

[0130] Those skilled in the art will conceive of various ways to reorder the operations described in the embodiments of this application. Furthermore, it should be noted that process details involved in one embodiment of this application are similarly applicable to other embodiments, or different embodiments can be combined.

[0131] Furthermore, some steps in the method embodiments can be equivalently replaced with other possible steps. Alternatively, some steps in the method embodiments may be optional and can be deleted in certain use cases. Alternatively, other possible steps may be added to the method embodiments. Moreover, the various method embodiments can be implemented individually or in combination. The above description is merely a specific implementation of this application, but the protection scope of this application is not limited thereto. Any changes or substitutions within the technical scope disclosed in this application should be covered within the protection scope of this application. Therefore, the protection scope of this application should be determined by the protection scope of the claims.

Claims

1. An electroplating solution, characterized in that, The electroplating solution includes: nickel salt, grain refiner, buffer, auxiliary brightener and main brightener; The primary brightener includes onium salt [A]. x [B] y ; The general formula for the structure of A is as follows (1): Where x and n are positive integers, and y is a natural number; R1 is selected from C1-C4 alkyl groups; When y = 0, R2 is selected from one of hydrogen atoms, unsaturated alkyl groups containing double bonds, aromatic hydrocarbon groups, and heteroatom groups; When y≥1, R2 is selected from unsaturated alkyl groups containing double bonds; The B is selected from unsaturated monomers with at least one alkyl group.

2. The electroplating solution according to claim 1, characterized in that, The unsaturated alkyl group containing double bonds includes one of methenoyl, vinyl, and propenyl; the aromatic hydrocarbon group includes one of phenyl, phenolic, halophenyl, and tolyl; and the heteroatom group includes one of hydroxyl, amino, mercapto, carboxyl, and amide.

3. The electroplating solution according to claim 1 or 2, characterized in that, The unsaturated monomer with at least one alkyl group includes one of acrylamide, acryloylglycine, methacrylamide, N,N-dimethylacrylamide, acrylic acid, vinylformamide, vinylacetamide, vinylcaprolactam, vinylpyrrolidone, vinylimidazolium, vinylpyridine, vinylbenzoic acid, allylamine, N,N-dimethylallylamine, vinyl acetate, isopropyl acetate, aminoethyl methacrylate, and dimethylaminoethyl methacrylate.

4. The electroplating solution according to any one of claims 1-3, characterized in that, The onium salt further includes anion selected from one of halogen-containing ions, hydrogen sulfate ions, and nitrate ions, wherein the halogen-containing ions include chloride ions, bromide ions, iodide ions, tetrafluoroborate ions, and hexafluorophosphate ions.

5. The electroplating solution according to any one of claims 1-4, characterized in that, The value of n is 1-5.

6. The electroplating solution according to any one of claims 1-5, characterized in that, The x range is 1-1000, and the y range is 0-1000.

7. The electroplating solution according to any one of claims 1-6, characterized in that, The concentration of the nickel salt in the electroplating solution is 1 g / L-500 g / L, the concentration of the grain refiner is 0.1 g / L-10 g / L, the concentration of the buffer is 1 g / L-100 g / L, the concentration of the auxiliary brightener is 10 ppm-1000 ppm, and the concentration of at least one primary brightener is 0.5 ppm-50 ppm.

8. The electroplating solution according to any one of claims 1-7, characterized in that, The general structural formula of A includes at least one of the following structures:

9. The electroplating solution according to any one of claims 1-8, characterized in that, The pH of the electroplating solution is 3-6.

10. The electroplating solution according to any one of claims 1-9, characterized in that, The nickel salt includes at least one of nickel aminosulfonate, nickel chloride, nickel sulfate, and nickel acetate; the grain refiner includes one of sodium saccharin, thiourea and its derivatives, and coumarin and its derivatives; the buffer includes one of boric acid, citric acid, and acetic acid; and the auxiliary brightener includes one of pyridinium hydroxypropanesulfonate, pyridinium propanesulfonate, 1,4-butynediol, sodium propargyl sulfonate, sodium allyl sulfonate, ethoxybutynediol, and propargyl alcohol.

11. An electroplating method using an electroplating solution, characterized in that, The method includes: The substrate to be electroplated is immersed in the electroplating solution according to any one of claims 1-10; At a preset temperature, an electric current is applied to the electroplating solution to form an electroplating layer on the surface of the substrate to be electroplated.

12. The electroplating method according to claim 11, characterized in that, The current density is 0.1ASD-10ASD, the preset temperature is 40℃-65℃, and the thickness of the electroplated layer is less than 15μm.

13. The application of the electroplating solution according to any one of claims 1-10 in electroplating metal casings, electroplating electronic device casings, and chip packaging.

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