A high corrosion resistance chemical nickel plating solution and preparation method thereof

Abstract

The present application relates to the field of chemical plating, and specifically to a highly corrosion-resistant chemical nickel plating solution and a preparation method thereof. The present invention discloses a highly corrosion-resistant chemical nickel plating solution, comprising the following components in concentration: 10 to 15 g / L of a complexing agent, 20 to 30 g / L of a nickel salt, 25 to 35 g / L of a reducing agent, 1 to 4 g / L of a buffer, 5 to 15 ppm of a stabilizer, and 80 to 120 ppm of a wetting agent, wherein the stabilizer is a mixture of KIO3 and thiourea. The present invention significantly improves the porosity of the coating and the corrosion resistance of the coating through the synergistic effect of multiple components, while enhancing the stability of the plating solution, and the present invention has a simple process, low cost, and is suitable for industrial production.

Description

Technical Field

[0001] The invention relates to the field of chemical plating, and in particular to a highly corrosion-resistant chemical nickel plating solution and a preparation method thereof. Background Art

[0002] Printed circuit boards (PCB), also known as printed circuit boards, are providers of electrical connections for electronic components. Printed circuit boards have evolved from single-layer to double-layer, multi-layer and flexible boards, and are constantly developing towards high precision, high density and high reliability. Continuously reducing size, reducing costs and improving performance will allow printed circuit boards to maintain strong vitality in the development of future electronic products. The future development trend of printed circuit board production and manufacturing technology is to develop in the direction of high density, high precision, fine aperture, fine wire, small pitch, high reliability, multi-layer, high-speed transmission, light weight and thinness in terms of performance.

[0003] Traditional printed circuit boards are mostly based on copper, but in recent years, there are more and more printed circuit boards with aluminum substrates. Neither copper nor aluminum substrates can be used as the final material of printed circuit boards. Taking aluminum substrates as an example, aluminum substrates cannot be used as a base for welding and binding, and their wear resistance is poor. Therefore, aluminum substrates generally need to be treated with chemical nickel-gold or chemical nickel-palladium-gold process to provide them with wear resistance, binding function, welding function, etc.

[0004] Chemical plating refers to the metal deposition process that is carried out by controlled chemical reduction under the catalytic effect of the metal surface without applying an external current. Because the plating process can only be carried out spontaneously on the surface of the substrate that has a catalytic effect on the reduction reaction, and once the reaction starts, the nickel generated by the reaction itself has a catalytic effect on the reduction reaction, so that the reduction reaction can continue, it is also called "autocatalytic deposition".

[0005] The existing plating solution has the following deficiencies during use: (1) the stability is not ideal and the plating solution is prone to decomposition; (2) the corrosion resistance of the coating is poor; (3) the coating is loose and has a large porosity. Summary of the invention

[0006] In order to solve the above technical problems, the first aspect of the present invention provides a high corrosion resistance chemical nickel plating solution, comprising the following components in concentration: 10-15 g / L of complexing agent, 20-30 g / L of nickel salt, 25-35 g / L of reducing agent, 1-4 g / L of buffer, 5-15 ppm of stabilizer, 80-120 ppm of wetting agent,

[0007] Wherein, the stabilizer is a mixture of KIO3 and thiourea.

[0008] As a preferred technical solution, the complexing agent includes at least one of glacial acetic acid, glycolic acid, lactic acid, oxalic acid, malonic acid, succinic acid, tartaric acid, glycine, alanine, salicylic acid, ethylenediaminetetraacetic acid, malic acid, citric acid, aspartic acid, and propionic acid.

[0009] As a preferred technical solution, the complexing agent is a combination of malic acid, citric acid and propionic acid.

[0010] As a preferred technical solution, the concentration ratio of KIO3 to thiourea is (1-3):1.

[0011] As a preferred technical solution, the nickel salt includes at least one of nickel sulfate, nickel chloride, nickel acetate, nickel sulfamate, and nickel hypophosphite.

[0012] As a preferred technical solution, the nickel salt is nickel sulfate.

[0013] As a preferred technical solution, it also includes components with the following concentrations: auxiliary agent 1-10 ppm, sodium succinate 1-10 g / L.

[0014] As a preferred technical solution, the auxiliary agent includes cysteine.

[0015] A second aspect of the present invention provides a method for preparing the chemical nickel plating solution, comprising the following steps:

[0016] (1) Add 50% deionized water to the pre-prepared plating liquid at room temperature;

[0017] (2) Then, add the complexing agent, nickel salt, and buffer in sequence while stirring until all are dissolved.

[0018] (3) Add the remaining ionized water, and then add the reducing agent, stabilizer, wetting agent, auxiliary agent, and sodium succinate and stir until all are dissolved; then adjust the pH value to 4.1-5.0 with sulfuric acid to obtain the product.

[0019] A third aspect of the present invention provides a nickel-plated product, which is prepared by immersing a workpiece to be plated in the nickel-plating solution to form a coating.

[0020] Beneficial effects: The present invention significantly improves the porosity of the coating and the corrosion resistance of the coating through the synergistic effect of multiple components, while enhancing the stability of the plating solution. The present invention has a simple process, low cost, and is suitable for industrial production. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is a SEM image of the nickel-plated layer in Example 9 of the present invention. DETAILED DESCRIPTION

[0022] In order to solve the above problems, the present invention provides a high corrosion-resistant chemical nickel plating solution, comprising the following components in concentration: 10-15 g / L of complexing agent, 20-30 g / L of nickel salt, 25-35 g / L of reducing agent, 1-4 g / L of buffer, 5-15 ppm of stabilizer, and 80-120 ppm of wetting agent.

[0023] As a preferred embodiment, the chemical nickel plating solution contains the following components in concentration: 12 g / L of complexing agent, 24 g / L of nickel salt, 30 g / L of reducing agent, 2 g / L of buffer, 10 ppm of stabilizer, and 100 ppm of wetting agent.

[0024] As a preferred embodiment, the chemical nickel plating solution further comprises the following components in concentration: auxiliary agent 1-10 ppm, sodium succinate 1-10 g / L.

[0025] Preferably, the chemical nickel plating solution further comprises components with the following concentrations: auxiliary agent 5 ppm, sodium succinate 6 g / L.

[0026] The unit ppm refers to mg / L.

[0027] Nickel salts

[0028] The nickel salt provides the Ni required in the chemical plating reaction process. 2+ .

[0029] As a preferred embodiment, the nickel salt includes at least one of nickel sulfate, nickel chloride, nickel acetate, nickel sulfamate, and nickel hypophosphite.

[0030] As a preferred embodiment, the nickel salt is nickel sulfate.

[0031] The applicant has found that the use of nickel sulfate as the main salt does not produce chloride ions that would reduce the corrosion resistance of the coating, and does not produce tensile stress.

[0032] reducing agent

[0033] Adding reducing agent to nickel plating solution to reduce Ni 2+ In order to deposit Ni on the workpiece to be plated, the reducing agent described in the present application contains two or more active hydrogens in its structure.

[0034] The reducing agent described in the present application includes but is not limited to sodium hypophosphite, sodium borohydride, alkylamine borane and hydrazine.

[0035] As a preferred embodiment, the reducing agent is sodium hypophosphite.

[0036] The applicant has found that when the reducing agent is sodium hypophosphite, a Ni-P coating is obtained, the P content is 7-14%, and the Ni-P coating has excellent performance.

[0037] Buffer

[0038] During the chemical nickel plating process, due to the presence of H + The pH value of the solution gradually decreases with the plating process. In order to stabilize the plating speed and ensure the quality of the coating, the chemical nickel plating system must be maintained within a certain pH range.

[0039] As an embodiment, the buffer includes but is not limited to borax, sodium acetate, succinic acid, sodium hydrogen succinate, sodium hydrogen citrate, sodium hydrogen malonate, and boric acid.

[0040] As a preferred embodiment, the buffer is borax.

[0041] The present application adds borax to interact with other components to offset the effect of a small amount of external acid or alkali and dilution on the pH value of the solution, so that the pH value fluctuates within a smaller range.

[0042] Stabilizer

[0043] The chemical nickel plating solution is a thermodynamically unstable system. Due to various reasons, such as local overheating, too high pH value, or the influence of certain impurities, some active particles will inevitably appear in the plating solution, causing the plating solution to undergo a violent autocatalytic reaction to produce a large amount of Ni-P black powder, resulting in the decomposition of the plating solution in a short period of time, escaping a large number of bubbles, and causing irreparable economic losses. The present application suppresses the spontaneous decomposition of the plating solution by adding a stabilizer, so that the plating process is carried out in an orderly manner under control.

[0044] The stabilizer is selected from at least one of compounds of Group VI elements S, Se, Te, oxygen-containing compounds, heavy metal ions, and water-soluble organic matter.

[0045] Examples of compounds of Group VI elements S, Se, and Te include, but are not limited to, thiourea, thiosulfate, and thiocyanate.

[0046] Examples of oxygen-containing compounds include, but are not limited to, AsO2 - IO3 - BrO3 - 、MoO4 2- .

[0047] Examples of heavy metal ions include, but are not limited to, Pb 2+ Sn 2+ , Sb 3+ .

[0048] Examples of water-soluble organic substances include, but are not limited to, maleic acid and itaconic acid.

[0049] As a preferred embodiment, the stabilizer is a mixture of KIO3 and thiourea.

[0050] As a preferred embodiment, the concentration ratio of KIO3 to thiourea is (1-3):1.

[0051] Preferably, the concentration ratio of KIO3 to thiourea is 2:1.

[0052] When the concentration of the reducing agent in the chemical nickel plating solution is 25-35 g / L, it is beneficial to form a complete coating on the substrate surface; however, the increase of the reducing agent will lead to a decrease in the stability of the plating solution. By adding the stabilizer, thiourea can preferentially or completely inhibit the H2 evolution reaction and Ni 2+ or H2PO2 - The reduction reaction of IO3 - With H2PO2 - The reaction causes the pH bond strength to increase, and the adsorbed IO3 - The double electric layer structure is changed, the surface adsorption degree is increased, and the dynamic process of the redox reaction is affected. However, the use of the two alone will cause the surface of the coating to be cellular particles, and the cellular tissue is connected into large protrusions, forming more loose and porous defects; by limiting the concentration ratio of KIO3 and thiourea to (1-3):1, the porosity of the coating is reduced. It is speculated that this is because the adsorption degree and adsorption strength of KIO3 and thiourea at the active sites are different. At different stages of the coating, the two work together to achieve stability while improving the loose structure of the coating. However, since the coating is doped with heteroatoms such as S, the corrosion resistance of the coating is reduced.

[0053] Complexing agent

[0054] As a preferred embodiment, the complexing agent includes at least one of glacial acetic acid, glycolic acid, lactic acid, oxalic acid, malonic acid, succinic acid, tartaric acid, glycine, alanine, salicylic acid, ethylenediaminetetraacetic acid, malic acid, citric acid, aspartic acid, and propionic acid.

[0055] As a preferred embodiment, the complexing agent is a combination of malic acid, citric acid and propionic acid.

[0056] Preferably, the concentration ratio of malic acid, citric acid and propionic acid is: 2:1:(3-8).

[0057] More preferably, the concentration ratio of malic acid, citric acid and propionic acid is 2:1:6.

[0058] Malic acid, also known as hydroxysuccinic acid, has an asymmetric carbon atom in its molecule. Malic acid is colorless needle-shaped crystals or white crystalline powder. The malic acid has three isomers: L-malic acid, D-malic acid and DL-malic acid. The malic acid described in this application is not particularly limited, and is preferably DL-malic acid with a CAS number of 6915-15-7. The malic acid described in this application was purchased from Shaanxi Chenming Biotechnology Co., Ltd.

[0059] Citric acid, also known as citric acid, has a CAS number of 77-92-9. It is a tricarboxylic acid compound, a strong organic acid, with 3 H + It can be ionized; it can be decomposed into various products when heated, and react with acids, bases, glycerol, etc. The ionization constants of citric acid are: pK1=3.13; pK2=4.76; pK3=6.40. Under the pH conditions of chemical nickel plating operation, most of the citric acid has been ionized into trivalent citrate ions.

[0060] Propionic acid, CAS No. 79-09-4, is a short-chain saturated fatty acid, a colorless oily liquid. The propionic acid can be purchased or made by yourself. The propionic acid can be obtained by direct oxidation of low-carbon hydrocarbons, that is, when acetic acid is produced by oxidation of low-carbon hydrocarbons as raw materials, formic acid and propionic acid can be co-produced, and propionic acid can be obtained after separation; the propionic acid can also be obtained by the Raper method, that is, ethylene reacts with carbon monoxide and water under the catalysis of carbonyl nickel to synthesize propionic acid in one step. The reaction conditions are 250-320°C and 10-30MPa.

[0061] The applicant has found that after adding malic acid, citric acid and propionic acid chelating agents, the chelating agents are adsorbed on the surface of the substrate, which increases the activity of the reaction and provides more activation energy for the hypophosphite to release active atomic hydrogen, thereby increasing the precipitation rate of the nickel layer. In particular, when the weight ratio of malic acid, citric acid and propionic acid is 2:1:(3-8), the corrosion resistance of the coating can be further improved. It is speculated that this is because, on the one hand, malic acid, citric acid, propionic acid and nickel ions form complexes of various structures, and the stability of different complexes is different, so that the orderly precipitation of nickel can be controlled. On the other hand, the chelating agent is adsorbed on the surface of the substrate in a specific form, and the precipitated nickel atoms grow and aggregate between the adsorbed chelating agent molecules, thereby generating a dense multi-layer coating, which improves the corrosion resistance of the coating.

[0062] Wetting Agents

[0063] As an embodiment, the wetting agent includes at least one of sodium succinate, sodium dodecylbenzene sulfonate, and sodium dodecyl sulfate.

[0064] As a preferred embodiment, the wetting agent is sodium succinate.

[0065] Preferably, the sodium succinate salt is sodium diisooctyl sulfosuccinate, with a CAS number of 577-11-7.

[0066] At the solid-liquid interface, since the valence bond force of atoms or molecules on the solid surface is unsaturated, the energy is relatively higher than that of the atoms or molecules inside, especially the metal surface is a high-energy surface. In this application, by adding sodium succinate, the solid-gas interface of the chemical plating system is easily replaced by the solid-liquid interface.

[0067] Additives

[0068] As a preferred embodiment, the auxiliary agent includes cysteine.

[0069] The CAS number of the cysteine ​​is 4371-52-2, and it is an aliphatic polar α-amino acid containing a thiol group.

[0070] The auxiliary agent also includes ascorbic acid;

[0071] The CAS number of the ascorbic acid is 299-36-5, also known as vitamin C, which is an acidic polyhydroxy compound containing 6 carbon atoms. The enediol group in the vitamin C molecular structure, especially the C3 OH, is strongly acidic (pK1=4.17) due to the conjugation effect; the C2 OH is extremely weakly acidic (pK2=11.75) due to the formation of intramolecular hydrogen bonds.

[0072] As a preferred embodiment, the concentration ratio of cysteine ​​to ascorbic acid is (1-3):1.

[0073] Preferably, the concentration ratio of cysteine ​​to ascorbic acid is 2:1.

[0074] The cysteine ​​molecules in the chemical nickel plating solution of the present invention are adsorbed on the active points of nickel crystal growth when the deposited layer grows, effectively inhibiting crystal growth, promoting the formation of crystal nuclei, and reducing the grain size of the coating. The applicant has found that when ascorbic acid is added to the chemical nickel plating solution and the concentration ratio of cysteine ​​to ascorbic acid is (1-3):1, the corrosion resistance of the coating can be improved, while adding ascorbic acid alone has no such effect. The possible reason is that in the overall nickel plating system, cysteine ​​and ascorbic acid cooperate with each other, and the two selectively adsorb on the crystal plane of nickel to obtain crystals with (111) crystal plane as the main surface, thereby improving the corrosion resistance of the coating.

[0075] As a preferred embodiment, the concentration ratio of the stabilizer to the auxiliary agent is (1-5):1.

[0076] As a preferred embodiment, the concentration ratio of the stabilizer to the auxiliary agent is 2:1.

[0077] The applicant has found that if the content of the stabilizer is high, it will compete with the auxiliary agent for adsorption. If the content of the stabilizer is low, the nickel precipitation rate is fast and the auxiliary agent cannot be adsorbed on the nickel nucleus in time, resulting in different growth orientations of the grains, which will reduce the corrosiveness of the coating.

[0078] The preparation method of the chemical nickel plating solution is not particularly limited.

[0079] As an embodiment, the method for preparing the chemical nickel plating solution comprises the following steps:

[0080] (1) Add 50% deionized water to the pre-prepared plating liquid at room temperature;

[0081] (2) Then, add the complexing agent, nickel salt, and buffer in sequence while stirring until all are dissolved.

[0082] (3) Add the remaining ionized water, and then add the reducing agent, stabilizer, wetting agent, auxiliary agent, and sodium succinate and stir until all are dissolved; then adjust the pH value to 4.1-5.0 with sulfuric acid to obtain the product.

[0083] The stirring speed is 500-1500 rpm.

[0084] A third aspect of the present invention provides a nickel-plated product, which is prepared by immersing a workpiece to be plated in the nickel-plating solution to form a coating.

[0085] The workpiece to be plated includes but is not limited to: a PCB circuit board, an alumina ceramic substrate, an aluminum nitride ceramic substrate, and a metal substrate.

[0086] The method for preparing the nickel plating layer is as follows: heating the chemical nickel plating solution to 80-90 degrees Celsius, placing the workpiece to be plated in the chemical nickel plating solution and plating for 10-40 minutes, and then preparing the nickel plating layer.

[0087] The present invention is described in detail below by way of examples. It is necessary to point out here that the following examples are only used to further illustrate the present invention and cannot be understood as limiting the scope of protection of the present invention. Some non-essential improvements and adjustments made by professionals and technicians in this field based on the content of the present invention above still belong to the scope of protection of the present invention.

[0088] In addition, unless otherwise stated, all raw materials used were commercially available.

[0089] Example

[0090] Example 1

[0091] A high corrosion-resistant chemical nickel plating solution comprises the following components in concentration: 10 g / L of a complexing agent, 20 g / L of a nickel salt, 25 g / L of a reducing agent, 1 g / L of a buffer, 5 ppm of a stabilizer, 80 ppm of a wetting agent, 1 ppm of an auxiliary agent, and 1 g / L of sodium succinate.

[0092] The complexing agent is a combination of malic acid, citric acid and propionic acid, and the concentration ratio of the malic acid, citric acid and propionic acid is 2:1:3.

[0093] The nickel salt is nickel sulfate;

[0094] The reducing agent is sodium hypophosphite;

[0095] The buffer is borax;

[0096] The stabilizer is a combination of KIO3 and thiourea, and the concentration ratio of KIO3 to thiourea is 1:1;

[0097] The wetting agent is sodium diisooctyl sulfosuccinate;

[0098] The auxiliary agents are cysteine ​​and ascorbic acid, and the concentration ratio of the cysteine ​​to the ascorbic acid is 1:1.

[0099] The preparation method of the chemical nickel plating solution comprises the following steps:

[0100] (1) Add 50% deionized water to the pre-prepared plating liquid at room temperature;

[0101] (2) Then, add the complexing agent, nickel salt, and buffer in sequence while stirring until all are dissolved.

[0102] (3) Add the remaining ionized water, and then add the reducing agent, stabilizer, wetting agent, auxiliary agent, and sodium succinate and stir until all are dissolved; then adjust the pH value to 4.5 with sulfuric acid to obtain the product.

[0103] The stirring speed is 800 rpm.

[0104] Example 2

[0105] A high corrosion-resistant chemical nickel plating solution comprises the following components in concentration: 15 g / L of complexing agent, 30 g / L of nickel salt, 35 g / L of reducing agent, 4 g / L of buffer, 15 ppm of stabilizer, 120 ppm of wetting agent, 10 ppm of auxiliary agent and 10 g / L of sodium succinate.

[0106] The complexing agent is a combination of malic acid, citric acid and propionic acid, and the concentration ratio of the malic acid, citric acid and propionic acid is 2:1:3.

[0107] The nickel salt is nickel sulfate;

[0108] The reducing agent is sodium hypophosphite;

[0109] The buffer is borax;

[0110] The stabilizer is a combination of KIO3 and thiourea, and the concentration ratio of KIO3 to thiourea is 1:1;

[0111] The wetting agent is sodium diisooctyl sulfosuccinate;

[0112] The auxiliary agents are cysteine ​​and ascorbic acid, and the concentration ratio of the cysteine ​​to the ascorbic acid is 1:1.

[0113] The specific steps of the method for preparing the chemical nickel plating solution are the same as those of Example 1.

[0114] Example 3

[0115] A high corrosion-resistant chemical nickel plating solution comprises the following components in concentration: 12 g / L of complexing agent, 24 g / L of nickel salt, 30 g / L of reducing agent, 2 g / L of buffer, 10 ppm of stabilizer, 100 ppm of wetting agent, 5 ppm of auxiliary agent and 6 g / L of sodium succinate.

[0116] The complexing agent is a combination of malic acid, citric acid and propionic acid, and the concentration ratio of the malic acid, citric acid and propionic acid is 2:1:3.

[0117] The nickel salt is nickel sulfate;

[0118] The reducing agent is sodium hypophosphite;

[0119] The buffer is borax;

[0120] The stabilizer is a combination of KIO3 and thiourea, and the concentration ratio of KIO3 to thiourea is 1:1;

[0121] The wetting agent is sodium diisooctyl sulfosuccinate;

[0122] The auxiliary agents are cysteine ​​and ascorbic acid, and the concentration ratio of the cysteine ​​to the ascorbic acid is 1:1.

[0123] The specific steps of the method for preparing the chemical nickel plating solution are the same as those of Example 1.

[0124] Example 4

[0125] A high corrosion-resistant chemical nickel plating solution comprises the following components in concentration: 12 g / L of complexing agent, 24 g / L of nickel salt, 30 g / L of reducing agent, 2 g / L of buffer, 10 ppm of stabilizer, 100 ppm of wetting agent, 5 ppm of auxiliary agent and 6 g / L of sodium succinate.

[0126] The complexing agent is a combination of malic acid, citric acid and propionic acid, and the concentration ratio of the malic acid, citric acid and propionic acid is 2:1:3.

[0127] The nickel salt is nickel sulfate;

[0128] The reducing agent is sodium hypophosphite;

[0129] The buffer is borax;

[0130] The stabilizer is a combination of KIO3 and thiourea, and the concentration ratio of KIO3 to thiourea is 3:1;

[0131] The wetting agent is sodium diisooctyl sulfosuccinate;

[0132] The auxiliary agents are cysteine ​​and ascorbic acid, and the concentration ratio of the cysteine ​​to the ascorbic acid is 1:1.

[0133] The specific steps of the method for preparing the chemical nickel plating solution are the same as those of Example 1.

[0134] Example 5

[0135] A high corrosion-resistant chemical nickel plating solution comprises the following components in concentration: 12 g / L of complexing agent, 24 g / L of nickel salt, 30 g / L of reducing agent, 2 g / L of buffer, 10 ppm of stabilizer, 100 ppm of wetting agent, 5 ppm of auxiliary agent and 6 g / L of sodium succinate.

[0136] The complexing agent is a combination of malic acid, citric acid and propionic acid, and the concentration ratio of the malic acid, citric acid and propionic acid is 2:1:3.

[0137] The nickel salt is nickel sulfate;

[0138] The reducing agent is sodium hypophosphite;

[0139] The buffer is borax;

[0140] The stabilizer is a combination of KIO3 and thiourea, and the concentration ratio of KIO3 to thiourea is 2:1;

[0141] The wetting agent is sodium diisooctyl sulfosuccinate;

[0142] The auxiliary agents are cysteine ​​and ascorbic acid, and the concentration ratio of the cysteine ​​to the ascorbic acid is 1:1.

[0143] The specific steps of the method for preparing the chemical nickel plating solution are the same as those of Example 1.

[0144] Example 6

[0145] A high corrosion-resistant chemical nickel plating solution comprises the following components in concentration: 12 g / L of complexing agent, 24 g / L of nickel salt, 30 g / L of reducing agent, 2 g / L of buffer, 10 ppm of stabilizer, 100 ppm of wetting agent, 5 ppm of auxiliary agent and 6 g / L of sodium succinate.

[0146] The complexing agent is a combination of malic acid, citric acid and propionic acid, and the concentration ratio of the malic acid, citric acid and propionic acid is 2:1:8.

[0147] The nickel salt is nickel sulfate;

[0148] The reducing agent is sodium hypophosphite;

[0149] The buffer is borax;

[0150] The stabilizer is a combination of KIO3 and thiourea, and the concentration ratio of KIO3 to thiourea is 2:1;

[0151] The wetting agent is sodium diisooctyl sulfosuccinate;

[0152] The auxiliary agents are cysteine ​​and ascorbic acid, and the concentration ratio of the cysteine ​​to the ascorbic acid is 1:1.

[0153] The specific steps of the method for preparing the chemical nickel plating solution are the same as those of Example 1.

[0154] Example 7

[0155] A high corrosion-resistant chemical nickel plating solution comprises the following components in concentration: 12 g / L of complexing agent, 24 g / L of nickel salt, 30 g / L of reducing agent, 2 g / L of buffer, 10 ppm of stabilizer, 100 ppm of wetting agent, 5 ppm of auxiliary agent and 6 g / L of sodium succinate.

[0156] The complexing agent is a combination of malic acid, citric acid and propionic acid, and the concentration ratio of the malic acid, citric acid and propionic acid is 2:1:6.

[0157] The nickel salt is nickel sulfate;

[0158] The reducing agent is sodium hypophosphite;

[0159] The buffer is borax;

[0160] The stabilizer is a combination of KIO3 and thiourea, and the concentration ratio of KIO3 to thiourea is 2:1;

[0161] The wetting agent is sodium diisooctyl sulfosuccinate;

[0162] The auxiliary agents are cysteine ​​and ascorbic acid, and the concentration ratio of the cysteine ​​to the ascorbic acid is 1:1.

[0163] The specific steps of the method for preparing the chemical nickel plating solution are the same as those of Example 1.

[0164] Example 8

[0165] A high corrosion-resistant chemical nickel plating solution comprises the following components in concentration: 12 g / L of complexing agent, 24 g / L of nickel salt, 30 g / L of reducing agent, 2 g / L of buffer, 10 ppm of stabilizer, 100 ppm of wetting agent, 5 ppm of auxiliary agent and 6 g / L of sodium succinate.

[0166] The complexing agent is a combination of malic acid, citric acid and propionic acid, and the concentration ratio of the malic acid, citric acid and propionic acid is 2:1:6.

[0167] The nickel salt is nickel sulfate;

[0168] The reducing agent is sodium hypophosphite;

[0169] The buffer is borax;

[0170] The stabilizer is a combination of KIO3 and thiourea, and the concentration ratio of KIO3 to thiourea is 2:1;

[0171] The wetting agent is sodium diisooctyl sulfosuccinate;

[0172] The auxiliary agents are cysteine ​​and ascorbic acid, and the concentration ratio of cysteine ​​to ascorbic acid is 3:1.

[0173] The specific steps of the method for preparing the chemical nickel plating solution are the same as those of Example 1.

[0174] Example 9

[0175] A high corrosion-resistant chemical nickel plating solution comprises the following components in concentration: 12 g / L of complexing agent, 24 g / L of nickel salt, 30 g / L of reducing agent, 2 g / L of buffer, 10 ppm of stabilizer, 100 ppm of wetting agent, 5 ppm of auxiliary agent and 6 g / L of sodium succinate.

[0176] The complexing agent is a combination of malic acid, citric acid and propionic acid, and the concentration ratio of the malic acid, citric acid and propionic acid is 2:1:6.

[0177] The nickel salt is nickel sulfate;

[0178] The reducing agent is sodium hypophosphite;

[0179] The buffer is borax;

[0180] The stabilizer is a combination of KIO3 and thiourea, and the concentration ratio of KIO3 to thiourea is 2:1;

[0181] The wetting agent is sodium diisooctyl sulfosuccinate;

[0182] The auxiliary agents are cysteine ​​and ascorbic acid, and the concentration ratio of the cysteine ​​to the ascorbic acid is 2:1.

[0183] The specific steps of the method for preparing the chemical nickel plating solution are the same as those of Example 1.

[0184] Example 10

[0185] A highly corrosion-resistant chemical nickel plating solution, the specific components and concentrations are the same as those in Example 9, except that the stabilizer is a combination of KIO3 and thiourea, and the concentration ratio of KIO3 to thiourea is 5:1;

[0186] The specific steps of the method for preparing the chemical nickel plating solution are the same as those of Example 1.

[0187] Embodiment 11

[0188] A highly corrosion-resistant chemical nickel plating solution, the specific components and concentrations are the same as those in Example 9, except that the stabilizer is a combination of KIO3 and thiourea, and the concentration ratio of KIO3 to thiourea is 0.2:1;

[0189] The specific steps of the method for preparing the chemical nickel plating solution are the same as those of Example 1.

[0190] Example 12

[0191] A highly corrosion-resistant chemical nickel plating solution, the specific components and concentrations are the same as those of Example 9, except that the complexing agent is a combination of malic acid, citric acid, and propionic acid, and the concentration ratio of the malic acid, citric acid, and propionic acid is 2:1:10.

[0192] The specific steps of the method for preparing the chemical nickel plating solution are the same as those of Example 1.

[0193] Embodiment 13

[0194] A highly corrosion-resistant chemical nickel plating solution, the specific components and concentrations are the same as those of Example 9, except that the complexing agent is a combination of malic acid, citric acid, and propionic acid, and the concentration ratio of the malic acid, citric acid, and propionic acid is 2:1:1.

[0195] The specific steps of the method for preparing the chemical nickel plating solution are the same as those of Example 1.

[0196] Embodiment 14

[0197] A highly corrosion-resistant chemical nickel plating solution, wherein the specific components and concentrations are the same as those in Example 9, except that the auxiliary agent is cysteine.

[0198] The specific steps of the method for preparing the chemical nickel plating solution are the same as those of Example 1.

[0199] Embodiment 15

[0200] A highly corrosion-resistant chemical nickel plating solution, the specific components and concentrations are the same as those of Example 9, except that the auxiliary agents are cysteine ​​and ascorbic acid, and the concentration ratio of cysteine ​​to ascorbic acid is 1:2.

[0201] The specific steps of the method for preparing the chemical nickel plating solution are the same as those of Example 1.

[0202] Example 16

[0203] A highly corrosion-resistant chemical nickel plating solution, wherein the specific components and concentrations are the same as those in Example 9, except that the concentration of the auxiliary agent is 10 ppm.

[0204] The specific steps of the method for preparing the chemical nickel plating solution are the same as those of Example 1.

[0205] Embodiment 17

[0206] A highly corrosion-resistant chemical nickel plating solution, wherein the specific components and concentrations are the same as those in Example 9, except that the stabilizer is a combination of KI and thiourea, and the concentration ratio of KI to thiourea is 2:1;

[0207] The specific steps of the method for preparing the chemical nickel plating solution are the same as those of Example 1.

[0208] Embodiment 18

[0209] A highly corrosion-resistant chemical nickel plating solution, the specific components and concentrations are the same as those of Example 9, except that the complexing agent is a combination of tartaric acid, citric acid, and propionic acid, and the concentration ratio of the tartaric acid, citric acid, and propionic acid is 2:1:1.

[0210] The specific steps of the method for preparing the chemical nickel plating solution are the same as those of Example 1.

[0211] Performance Testing

[0212] The printed circuit board was nickel plated with the chemical nickel plating solution provided in Examples 1-18, and the method was as follows: the chemical nickel plating solution was heated to 85 degrees Celsius, and the printed circuit board was placed in the chemical nickel plating solution for plating for 20 minutes, and the product was prepared. The porosity and corrosion resistance of the products prepared in each example were tested, and the results are shown in Table 1.

[0213] (1) Porosity test:

[0214] The test method is: under the conditions of temperature of 23±3 degrees Celsius and relative humidity of <55%, pour nitric acid into a beaker, place it in a desiccator, cover it with a lid, and place it for 30±5 minutes; bind the sample to be tested with polytetrafluoroethylene tape and hang it in the desiccator; take out the sample after placing it for 75±5 minutes, irradiate it with an incandescent lamp at an angle of 15 degrees, and observe the number of corroded pores under a 1000x microscope.

[0215] The criteria for judging the number of pores are as follows:

[0216] Pore ​​size Count the number of pores Maximum diameter ≤0.05mm 0 0.05mm<Maximum diameter<0.1mm 1 0.1mm≤Maximum diameter<0.2mm 2 Maximum diameter ≥0.2mm 5

[0217] Judgment standard: ≤5 per square millimeter is qualified, otherwise it is unqualified.

[0218] (2) Plating solution stability test: The nickel plating solution of each embodiment was subjected to a stability test. The test method was as follows: 100 mL of chemical nickel plating solution was taken, heated to 84 degrees Celsius, 1 mL of palladium chloride activation solution (a palladium chloride aqueous solution with a concentration of 100 mg / L) was dripped into the chemical nickel plating solution, and the decomposition time of the plating solution was observed and recorded. The results are shown in Table 1.

[0219] (3) Corrosion resistance test: The salt spray corrosion test of the coating was carried out in accordance with JIS Z2371-2000. The test used a 5% NaCl aqueous solution, the pH value of the sodium chloride solution was controlled to be in the range of 6.5 to 7.2, the test chamber temperature was 35°C ± 2°C, and the test surface of the sample was 20° from the vertical direction.

[0220] Corrosion resistance evaluation standard is (select 5000mm 2 area):

[0221] Corrosion area% Number of reviews 0.00 10 More than 0.02, less than 0.10 9 More than 0.10, less than 0.25 8 More than 0.25, less than 0.5 7 More than 0.5, less than 1.0 6 More than 1.0, less than 2.5 5 More than 2.5, less than 5 4 More than 5, less than 10 3 More than 10, less than 25 2 Over 25, Under 50 1 More than 50 0

[0222] Table 1. Performance test results

[0223]

[0224]

[0225] The above is only a preferred embodiment of the present invention and is not intended to limit the invention in other forms. Any technician familiar with the profession may use the technical content disclosed above to change or modify it into an equivalent embodiment with equivalent changes. However, any simple modification, equivalent change and modification made to the above embodiment based on the technical essence of the present invention without departing from the content of the technical solution of the present invention still falls within the protection scope of the technical solution of the present invention.

Claims

1. A highly corrosion-resistant chemical nickel plating solution, characterized in that: Contains the following components in concentration: complexing agent 12g / L, nickel salt 24g / L, reducing agent 30g / L, buffer 2g / L, stabilizer 10ppm, wetting agent 100ppm, auxiliary agent 5ppm, sodium succinate 6g / L; The complexing agent is a combination of malic acid, citric acid and propionic acid, and the concentration ratio of malic acid, citric acid and propionic acid is 2:1:6; The nickel salt is nickel sulfate; The reducing agent is sodium hypophosphite; The buffer is borax; The stabilizer is a combination of KIO3 and thiourea, and the concentration ratio of KIO3 to thiourea is 2:1; The wetting agent is sodium diisooctyl sulfosuccinate; The auxiliary agent is cysteine ​​and ascorbic acid, and the concentration ratio of cysteine ​​to ascorbic acid is 2:1; The preparation method of the chemical nickel plating solution comprises the following steps: (1) Add 50% deionized water to the pre-prepared plating liquid at room temperature; (2) Then, add the complexing agent, nickel salt, and buffer in sequence while stirring until all are dissolved. (3) Add the remaining ionized water, and then add the reducing agent, stabilizer, wetting agent, auxiliary agent, and sodium succinate and stir until all are dissolved; then adjust the pH value to 4.5 with sulfuric acid to obtain the product.

2. A method for preparing a chemical nickel plating solution as claimed in claim 1, characterized in that: The following steps are involved: (1) Add 50% deionized water to the pre-prepared plating liquid at room temperature; (2) Then, add the complexing agent, nickel salt, and buffer in sequence while stirring until all are dissolved. (3) Add the remaining ionized water, and then add the reducing agent, stabilizer, wetting agent, auxiliary agent, and sodium succinate and stir until all are dissolved; then adjust the pH value to 4.5 with sulfuric acid to obtain the product.

3. A nickel-plated product, characterized in that: The nickel plating method is prepared by immersing the workpiece to be plated in the nickel plating solution of claim 1 to form a plating film.

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