Chemical nickel-palladium-gold plating solution

Abstract

The invention belongs to the field of chemical plating, and particularly discloses a chemical nickel-palladium-gold plating solution which comprises a nickel plating solution, a palladium plating solution and a gold plating solution. The nickel plating solution comprises, by mass concentration, 4-6 g / L of nickel salt, 3-7 g / L of a complexing agent, 20-60 mg / L of a stabilizer, 10-20 g / L of a reducing agent, 30-60 mg / L of an anti-pinhole agent and 90-180 mg / L of a plating starting agent. A plating layer prepared by adopting the chemical plating solution has excellent appearance, the surface of the plating layer is bright and free of pinholes, metal bumps and chromatic aberration, the gold wire bonding yield is 100%, the chemical plating solution has excellent binding force, corrosion resistance and the like, and the chemical plating solution is good in stability, long in service life and not prone to dissociation, can be applied to the surface treatment process of a carrier plate, and can be widely applied to the surface treatment process of the carrier plate. And the requirements of high-efficiency and high-performance nickel-palladium-gold plating of domestic support plates are met

Description

Technical Field

[0001] The invention belongs to the field of chemical plating, and in particular relates to a chemical nickel-palladium-gold plating solution. Background Art

[0002] The prior art usually uses nickel-palladium-gold plating to treat the surface of copper substrates. However, the traditional nickel-palladium-gold plating solution has the following problems: (1) The nickel plating solution requires high temperature and the nickel plating layer has poor uniformity, and there is a pinhole problem in the nickel layer; (2) When the traditional palladium plating solution is produced, a large load dragging cylinder is required to bring up the activity before production. The dragging cylinder process will inevitably consume a large amount of palladium salt, which is too costly; (3) The traditional gold plating solution has a low gold deposition rate and is prone to gold surface color difference. These problems seriously restrict the use of chemical nickel-palladium-gold plating solution for copper substrate surface treatment. Summary of the invention

[0003] In order to overcome the problems existing in the prior art, one of the objectives of the present invention is to provide a chemical plating solution.

[0004] A second object of the present invention is to provide a chemical plating method.

[0005] A third object of the present invention is to provide an application of the chemical plating solution in the field of metal plating of products.

[0006] In order to achieve the above object, the technical solution adopted by the present invention is:

[0007] A first aspect of the present invention provides a chemical plating solution, including a nickel plating solution, a palladium plating solution and a gold plating solution;

[0008] The nickel plating solution comprises the following components in mass concentrations: 4-6 g / L nickel salt, 3-7 g / L complexing agent, 20-60 mg / L stabilizer, 10-20 g / L reducing agent, 30-60 mg / L anti-pinhole agent, and 90-180 mg / L plating agent;

[0009] The palladium plating solution comprises the following components in mass concentrations: palladium salt 0.8-1.2 g / L, complex complexing agent 6-12 g / L, accelerator 0.1-0.5 g / L, stabilizer 20-80 mg / L, reducing agent 10-20 g / L, and homogenizer 3-6 g / L;

[0010] The gold plating solution includes the following components in mass concentrations: 1-3 g / L of gold salt, 40-80 mg / L of accelerator, 5-10 g / L of complexing agent, 4-8 g / L of reducing agent, 30-90 mg / L of stabilizer, and 1-3 g / L of homogenizing agent. Preferably, the chemical plating solution is a chemical plating solution for surface treatment of copper substrates; more preferably, the chemical plating solution is a chemical plating solution for surface treatment of carrier boards.

[0011] Preferably, in the nickel plating solution, the plating agent includes tris (3-hydroxypropyltriazole methyl) amine. In the present invention, the plating agent can improve the uniformity of nickel on the plated layer and promote the continuous nucleation of nickel. In addition, the plating agent will not decompose as the temperature of the nickel plating solution increases. Compared with traditional chemical nickel plating, the temperature of nickel plating can be reduced, and it does not need to reach 80°C, so as to achieve medium-temperature nickel plating, while still ensuring a plating speed of 8-10 microinches / min.

[0012] Preferably, in the nickel plating solution, the anti-pinhole agent includes bis(2-dimethylaminoethyl)ether. The present invention uses bis(2-dimethylaminoethyl)ether as an anti-pinhole agent, which has a great improvement effect on the pinhole effect of the coating, can effectively reduce the pinhole porosity, and will not produce pores even without equipment vibration. Compared with traditional anti-pinhole agents, it also has the effect of wetting the surface and improving the uniformity of the unit cell.

[0013] Preferably, in the nickel plating solution, the complexing agent includes 3,5-pyridinedicarboxylic acid. The complexing agent in the present invention can improve the stability of the nickel plating solution, extend the service life of the nickel plating solution, and prevent the nickel plating solution from precipitating during long-term use.

[0014] Preferably, in the nickel plating solution, the stabilizer includes 2-piperidinol. The stabilizer in the present invention can improve the ability to withstand large loads. At present, some chemical nickel solutions have a load of more than 0.6 dm during use. 2 When the trough phenomenon occurs, the stabilizer in the present invention can achieve a load of 1dm 2 , no precipitation tank will appear within 5MTO.

[0015] Preferably, in the nickel plating solution, the reducing agent includes at least one of sodium hypophosphite and potassium hypophosphite. The reducing agent in the present invention is used to reduce nickel salt so that nickel can be uniformly deposited on the surface of the workpiece to be plated. It has high reducing activity and can continuously and quickly reduce nickel.

[0016] Preferably, in the nickel plating solution, the nickel salt is selected from at least one of nickel sulfate, nickel chloride, nickel nitrate, nickel acetate, nickel citrate, nickel fluoroborate and nickel sulfamate.

[0017] Preferably, in the palladium plating solution, the palladium salt is selected from tetraamminepalladium sulfate, palladium chloride, palladium nitrate, dichlorotetraamminepalladium (Pd(NH3)4Cl2), dibromotetraamminepalladium (Pd(NH3)4Br2), diiodotetraamminepalladium (Pd(NH3)4I2), dinitrite tetraamminepalladium (Pd(NH3)4(ONO)2), dinitrate tetraamminepalladium (Pd(NH3)4(NO3)2), disulfite tetraamminepalladium (Pd(NH3)4(SO3)2), dinitrotetraamminepalladium (Pd(NH3)4(NO2)2), At least one of diamminepalladium dichloride (Pd(NH3)2Cl2), diamminepalladium dibromide (Pd(NH3)2Br2), diamminepalladium diiodide (Pd(NH3)2I2), diamminepalladium dinitrite (Pd(NH3)2(ONO)2), diamminepalladium dinitrate (Pd(NH3)2(NO3)2), diamminepalladium disulfite (Pd(NH3)2(SO3)2), diamminepalladium disulfate (Pd(NH3)2(SO4)2), and diamminepalladium dinitro (Pd(NH3)2(NO2)2).

[0018] Preferably, in the palladium plating solution, the composite complexing agent includes a mixture of at least one selected from ethylenediamine, propylenediamine, butylene diamine and bis(3-aminopropyl)-1,3-propylenediamine; further preferably, in the palladium plating solution, the composite complexing agent is a mixture of ethylenediamine and bis(3-aminopropyl)-1,3-propylenediamine in a mass ratio of (1 to 10):1. The present invention adopts a composite complexing agent, which can better improve the stability of the palladium plating solution, extend the service life of the palladium plating solution, and make the palladium plating solution less likely to precipitate during long-term use.

[0019] Preferably, in the palladium plating solution, the promoter includes 4-piperidinecarboxamide. Since chemical palladium is highly active, in order to prevent the precipitation tank, the existing palladium plating solution will add excessive complexing agents and stabilizers to inhibit the activity of palladium. Therefore, during production, a large load drag cylinder is required to bring up the activity before production. A large amount of palladium salt will inevitably be consumed during the drag cylinder process, and the cost is too high. The present invention introduces the promoter 4-piperidinecarboxamide into the palladium plating solution, which can make chemical palladium plating free of plating, thereby solving the problem of high cost caused by the large consumption of palladium salts during the drag cylinder process.

[0020] Preferably, in the palladium plating solution, the reducing agent is selected from at least one of sodium formate, potassium formate, sodium acetate, potassium acetate, sodium propionate, potassium propionate, sodium butyrate and potassium butyrate. The reducing agent in the present invention is used to reduce palladium salts so that palladium can be uniformly deposited on the surface of the workpiece to be plated. It has high reducing activity and can continuously and rapidly reduce palladium.

[0021] Preferably, in the palladium plating solution, the stabilizer includes at least one of 5-methylindole-2-methyl ester, 5-methylindole-2-carboxylic acid methyl ester, 5-methylindole-2-carboxylic acid propyl ester, 5-methylindole-2-carboxylic acid butyl ester, and 5-methylindole-2-carboxylic acid pentyl ester. In the present invention, the stabilizer used in the palladium plating solution can expand the temperature adaptability range of chemical palladium plating, so that the palladium plating solution can be stably plated with palladium within 58 to 68°C. For every 1°C increase in temperature of the traditional chemical palladium plating solution, the deposition rate increases by 20% or more, and the stabilizer of the present invention can effectively solve this problem, so that the deposition rate increases by less than 5% for every 1°C increase in temperature.

[0022] Preferably, in the palladium plating solution, the homogenizer includes at least one of 2-methylthiazole-5-carboxylic acid, 2-methylthiazole-5-acetic acid, and 4-methylthiazole-5-propionic acid. The homogenizer in the palladium plating solution can promote the uniformity of palladium deposition and ensure that no leakage plating occurs. In addition, the homogenizer in the gold plating solution can also improve the uniformity of the gold plating layer. During the growth of gold particles, the gold particles will preferentially adsorb higher areas to inhibit the rapid growth of gold particles.

[0023] Preferably, in the gold plating solution, the gold salt is selected from at least one of gold sulfite, gold chloroaurate, gold thiosulfate, and gold thiomalate.

[0024] Preferably, in the gold plating solution, the reducing agent includes thiosemicarbazide. The reducing agent in the present invention is used to reduce gold salt so that gold can be deposited on the surface of the workpiece to be plated. It has high reducing activity and can continuously and rapidly reduce gold.

[0025] Preferably, in the gold plating solution, the accelerator includes at least one of pyrrole-1-propionic acid, pyrrole-1-butyric acid, pyrrole-1-formic acid, pyrrole-1-acetic acid, and pyrrole-1-valeric acid. In order to solve the problem that the thick palladium gold deposition rate is slow or even cannot be reduced to gold, the present invention introduces an accelerator pyrrole-1-propionic acid into the gold plating solution, which can play a bridging role, so that gold can be continuously nucleated, promote the rapid deposition of gold without color difference, and prevent the occurrence of leakage plating, thereby performing gold plating on the surface of the thick palladium layer. In addition, the accelerator and the uniformizer work synergistically to improve the compactness of the coating.

[0026] Preferably, in the gold plating solution, the leveling agent includes at least one of methylpyrrole-2-carboxylate, ethylpyrrole-2-carboxylate, butylpyrrole-2-carboxylate, propylpyrrole-2-carboxylate, and pyrrole-2-carboxylate. The leveling agent in the present invention can promote uniform deposition of gold, which is conducive to obtaining a plating layer with uniform gold dispersion.

[0027] Preferably, in the gold plating solution, the stabilizer includes at least one of 2-piperidinemethanol, 2-piperidineethanol, 2-piperidinepropanol, and 2-piperidinebutanol. The stabilizer in the present invention can inhibit the disordered growth of gold particles, reduce the penetration of gold particles, and attack the bottom of the substrate at the edge gap of the photoresist.

[0028] Preferably, in the gold plating solution, the complexing agent includes histidine.

[0029] Preferably, at least one selected from the group consisting of nickel plating solution, palladium plating solution and gold plating solution uses water as a solvent; further preferably, the nickel plating solution, palladium plating solution and gold plating solution all use water as a solvent.

[0030] Preferably, the pH of the nickel plating solution is 4.4-4.8.

[0031] Preferably, the pH of the palladium plating solution is 6.2-6.8.

[0032] Preferably, the pH of the gold plating solution is 7.2-7.8.

[0033] A second aspect of the present invention provides a chemical plating method, comprising the following steps:

[0034] The workpiece to be plated is immersed in the chemical plating solution described in the first aspect of the present invention and heated to perform chemical plating to form a plating layer on the surface of the workpiece to be plated.

[0035] Preferably, the chemical plating method comprises the following steps: immersing the workpiece to be plated in a nickel plating solution at a temperature of 70-80° C. for chemical plating to form a nickel plating layer on the surface of the workpiece to be plated.

[0036] Preferably, the chemical plating method comprises the following steps: immersing the workpiece to be plated in a palladium plating solution at a temperature of 58-68° C. for chemical plating to form a palladium plating layer on the surface of the workpiece to be plated.

[0037] Preferably, the chemical plating method comprises the following steps: immersing the workpiece to be plated in a gold plating solution at a temperature of 60-70° C. for chemical plating to form a gold plating layer on the surface of the workpiece to be plated.

[0038] Preferably, the workpiece to be plated comprises a copper substrate.

[0039] The third aspect of the present invention provides the use of the chemical plating solution described in the first aspect of the present invention in the field of metal plating of products.

[0040] Preferably, the product comprises an electronic device, an integrated circuit, a printed circuit board, a relay or a connector.

[0041] The beneficial effects of the present invention are as follows: the coatings prepared by the chemical plating solution of the present invention have excellent appearance, the coating surface is bright without pinholes, metal nodules, or color difference, the gold wire good rate is 100%, and the coating has excellent bonding strength and corrosion resistance. The chemical plating solution has good stability, a long service life, and is not prone to precipitation. The coating can be applied to the surface treatment process of a substrate, meeting the domestic demand for high-efficiency and high-performance nickel-palladium-gold plating of substrates. DETAILED DESCRIPTION

[0042] The specific implementation of the present invention is further described in detail below in conjunction with examples, but the implementation and protection of the present invention are not limited thereto. It should be noted that if there are processes that are not particularly described in detail below, they can be implemented or understood by those skilled in the art with reference to the prior art. The reagents or instruments used that do not indicate the manufacturer are all conventional products that can be purchased commercially.

[0043] Nickel Plating Example

[0044] The chemical nickel plating solution in Example 1 and Comparative Examples 1 to 4 uses sodium hydroxide with a mass concentration of 5% and hydrochloric acid solution with a volume concentration of 5% to adjust the pH to 4.6.

[0045] Example 1

[0046] This example provides a chemical nickel plating solution, including the following components in mass concentrations: 5 g / L nickel sulfate, 5 g / L 3,5-pyridinedicarboxylic acid, 40 mg / L 2-piperidinemethanol, 15 g / L sodium hypophosphite, 45 mg / L bis(2-dimethylaminoethyl) ether, 60 mg / L tris(3-hydroxypropyltriazolemethyl)amine, and the solvent is deionized water.

[0047] The pH of the chemical nickel plating solution is 4.6.

[0048] When the chemical nickel plating solution in this example is used, the copper substrate needs to be subjected to chemical reduction nickel plating at an operating temperature of 75° C. for 20 minutes, thereby forming a nickel plating layer on the surface of the copper substrate.

[0049] Comparative Example 1

[0050] This example provides a chemical nickel plating solution, including the following components in mass concentrations: 5 g / L nickel sulfate, 40 mg / L 2-piperidinemethanol, 15 g / L sodium hypophosphite, 45 mg / L bis(2-dimethylaminoethyl) ether, 60 mg / L tris(3-hydroxypropyltriazolemethyl)amine, and the solvent is deionized water.

[0051] The pH of the chemical nickel plating solution is 4.6.

[0052] When the chemical nickel plating solution in this example is used, the copper substrate needs to be subjected to chemical reduction nickel plating at an operating temperature of 75° C. for 20 minutes, thereby forming a nickel plating layer on the surface of the copper substrate.

[0053] Comparative Example 2

[0054] This example provides a chemical nickel plating solution, including the following components in mass concentrations: 5 g / L nickel sulfate, 5 g / L 3,5-pyridinedicarboxylic acid, 15 g / L sodium hypophosphite, 45 mg / L bis(2-dimethylaminoethyl) ether, 60 mg / L tris(3-hydroxypropyltriazolemethyl)amine, and the solvent is deionized water.

[0055] The pH of the chemical nickel plating solution is 4.6

[0056] When the chemical nickel plating solution in this example is used, the copper substrate needs to be subjected to chemical reduction nickel plating at an operating temperature of 75° C. for 20 minutes, thereby forming a nickel plating layer on the surface of the copper substrate.

[0057] Comparative Example 3

[0058] This example provides a chemical nickel plating solution, including the following components in mass concentrations: 5 g / L nickel sulfate, 5 g / L 3,5-pyridinedicarboxylic acid, 40 mg / L 2-piperidinemethanol, 15 g / L sodium hypophosphite, 60 mg / L tris(3-hydroxypropyltriazolemethyl)amine, and the solvent is deionized water.

[0059] The pH of the chemical nickel plating solution is 4.6.

[0060] When the chemical nickel plating solution in this example is used, the copper substrate needs to be subjected to chemical reduction nickel plating at an operating temperature of 75° C. for 20 minutes, thereby forming a nickel plating layer on the surface of the copper substrate.

[0061] Comparative Example 4

[0062] This example provides a chemical nickel plating solution, including the following components in mass concentrations: 5 g / L nickel sulfate, 5 g / L 3,5-pyridinedicarboxylic acid, 40 mg / L 2-piperidinemethanol, 15 g / L sodium hypophosphite, 45 mg / L bis(2-dimethylaminoethyl) ether, and the solvent is deionized water.

[0063] pH 4.6

[0064] When the chemical nickel plating solution in this example is used, the copper substrate needs to be subjected to chemical reduction nickel plating at an operating temperature of 75° C. for 20 minutes, thereby forming a nickel plating layer on the surface of the copper substrate.

[0065] The following nickel plating index evaluation method was used to evaluate the performance of the nickel plating solutions in Example 1 and Comparative Examples 1 to 4, specifically:

[0066] A1. Stability index: During the process of depositing nickel on the copper substrate, chemical nickel plating solution is continuously added. When the life of the nickel plating solution ends, the content of the main salt added is recorded. The cycle of the nickel plating solution (MTO) = the content of the main salt added / the content of the main salt required to start the tank. The load during the stability index test is 1dm 2 Excellent stability refers to no troughing at 5MTO and above; good stability index refers to no troughing at 4MTO-5MTO (excluding 5MTO); poor stability index refers to no troughing at 3-4MTO (excluding 4MTO); poor stability index refers to no troughing below 3MTO (excluding 3MTO).

[0067] A2. Surface indicators: Excellent surface indicators refer to the nickel plating surface without pinholes and bright without nickel nodules; excellent surface indicators refer to the nickel plating surface with individual pinholes and bright with individual nickel nodules; poor surface indicators refer to the nickel plating surface with significantly more pinholes and nickel nodules but bright; poor surface indicators refer to the nickel plating surface with many pinholes and nickel nodules and dark color.

[0068] A3. Gold wire punching index: An excellent gold wire punching index means that twenty gold wires are punched continuously on the surface of the substrate, and the yield rate meets 100% for excellent; the yield rate is 90-100% (not including 100%) for good; the yield rate is 80-90% (not including 90%) for poor; and the yield rate below 80% is poor.

[0069] A4, bonding strength index: The bonding strength index is excellent if the tape will not peel off after being torn three times; it is good if there is slight edge peeling; it is poor if there is edge peeling; it is poor if there is peeling of the middle edge.

[0070] The performance index test results of the chemical nickel plating solution in Example 1 and Comparative Examples 1 to 4 obtained by the above evaluation method are shown in Table 1 below:

[0071] Table 1 Performance index test results of nickel plating solution in Example 1 and Comparative Examples 1 to 4

[0072] Test Group Stability index Surface indicators Gold line indicator Binding index Example 1 excellent excellent excellent excellent Comparative Example 1 Difference Difference Difference Difference Comparative Example 2 good good good good Comparative Example 3 excellent good good good Comparative Example 4 excellent good good good

[0073] It can be seen from Table 1 that compared with the nickel plating solution in Example 1, the nickel plating solution in Comparative Example 1 lacks a complexing agent, and the stability index, surface index, gold wire index and bonding strength are all reduced to poor; the nickel plating solution in Comparative Example 2 lacks a stabilizer, and the stability index, surface index, gold wire index and bonding strength are all reduced to good; the nickel plating solution in Comparative Example 3 lacks an anti-pinhole agent, and the nickel plating solution in Comparative Example 4 lacks a plating agent, and the surface indexes, gold wire indexes and bonding strength of both are reduced to good. It can be seen that the components of the nickel plating solution in the present invention have a synergistic effect, and the lack of any component will cause a decrease in overall performance.

[0074] Palladium Plating Example

[0075] The pH of the chemical palladium plating solution in Example 2 and Comparative Examples 5 to 8 was adjusted to 5.7 using sodium hydroxide solution with a mass concentration of 5% and a sulfuric acid solution with a volume concentration of 5%.

[0076] Example 2

[0077] This example provides a chemical palladium plating solution, including the following components in mass concentrations: 1 g / L tetraamminepalladium sulfate, 4.5 g / L ethylenediamine, 1.5 g / L bis(3-aminopropyl)-1,3-propylenediamine, 0.25 g / L 4-piperidinecarboxamide, 60 mg / L 5-methylindole-2-methylate, 15 g / L sodium formate, 4.5 g / L 2-methylthiazole-5-carboxylic acid, and the solvent is deionized water.

[0078] The pH of the chemical palladium plating solution is 5.7.

[0079] When the chemical palladium plating solution in this example is used, the copper substrate with a nickel-plated layer prepared in Example 1 needs to be subjected to chemical reduction palladium plating at an operating temperature of 62° C. for 10 minutes, thereby forming a palladium-plated layer on the surface of the nickel-plated layer.

[0080] Comparative Example 5

[0081] This example provides a chemical palladium plating solution, including the following components in mass concentrations: 1 g / L tetraamminepalladium sulfate, 0.25 g / L 4-piperidinecarboxamide, 60 mg / L 5-methylindole-2-methyl ester, 15 g / L sodium formate, 4.5 g / L 2-methylthiazole-5-carboxylic acid, and the solvent is deionized water.

[0082] The pH of the chemical palladium plating solution is 5.7.

[0083] When the chemical palladium plating solution in this example is used, the copper substrate with a nickel-plated layer prepared in Example 1 needs to be subjected to chemical reduction palladium plating at an operating temperature of 62° C. for 10 minutes, thereby forming a palladium-plated layer on the surface of the nickel-plated layer.

[0084] Comparative Example 6

[0085] This example provides a chemical palladium plating solution, including the following components in mass concentrations: 1 g / L tetraamminepalladium sulfate, 4.5 g / L ethylenediamine, 1.5 g / L bis(3-aminopropyl)-1,3-propylenediamine, 0.25 g / L 4-piperidinecarboxamide, 15 g / L sodium formate, 4.5 g / L 2-methylthiazole-5-carboxylic acid, and the solvent is deionized water.

[0086] The pH of the chemical palladium plating solution is 5.7.

[0087] When the chemical palladium plating solution in this example is used, the copper substrate with a nickel-plated layer prepared in Example 1 needs to be subjected to chemical reduction palladium plating at an operating temperature of 62° C. for 10 minutes, thereby forming a palladium-plated layer on the surface of the nickel-plated layer.

[0088] Comparative Example 7

[0089] This example provides a chemical palladium plating solution, including the following components in mass concentrations: 1 g / L tetraamminepalladium sulfate, 4.5 g / L ethylenediamine, 1.5 g / L bis(3-aminopropyl)-1,3-propylenediamine, 60 mg / L 5-methylindole-2-methylate, 15 g / L sodium formate, 4.5 g / L 2-methylthiazole-5-carboxylic acid, and the solvent is deionized water.

[0090] The pH of the chemical palladium plating solution is 5.7.

[0091] When the chemical palladium plating solution in this example is used, the copper substrate with a nickel-plated layer prepared in Example 1 needs to be subjected to chemical reduction palladium plating at an operating temperature of 62° C. for 10 minutes, thereby forming a palladium-plated layer on the surface of the nickel-plated layer.

[0092] Comparative Example 8

[0093] This example provides a chemical palladium plating solution, including the following components in mass concentrations: 1 g / L tetraamminepalladium sulfate, 4.5 g / L ethylenediamine, 1.5 g / L bis(3-aminopropyl)-1,3-propylenediamine, 0.25 g / L 4-piperidinecarboxamide, 60 mg / L 5-methylindole-2-methyl ester, 15 g / L sodium formate, and the solvent is deionized water.

[0094] The pH of the chemical palladium plating solution is 5.7.

[0095] When the chemical palladium plating solution in this example is used, the copper substrate with a nickel-plated layer prepared in Example 1 needs to be subjected to chemical reduction palladium plating at an operating temperature of 62° C. for 10 minutes, thereby forming a palladium-plated layer on the surface of the nickel-plated layer.

[0096] The following palladium plating index evaluation method was used to evaluate the performance of the chemical palladium plating solution in Example 2 and Comparative Examples 5 to 8, specifically:

[0097] B1. Stability index: An excellent stability index means that the tank liquid is precipitated within one month or more under the production temperature environment; a good stability index means that the tank liquid is precipitated within 20-30 days under the production temperature environment (excluding 30 days); a poor stability index means that the tank liquid is precipitated within 10-20 days under the production temperature environment (excluding 20 days); a poor stability index means that the tank liquid is precipitated within 10 days under the production temperature environment (excluding 10 days).

[0098] B2. Appearance index: Excellent appearance index refers to bright white coating; good appearance index refers to white coating but slightly insufficient brightness; poor appearance index refers to slightly dark coating; poor appearance index refers to blackening and yellowing.

[0099] B3. Gold wire punching index: An excellent gold wire punching index means that twenty gold wires are punched continuously on the surface of the substrate, and the yield rate meets 100% for excellent; the yield rate is 90-100% (not including 100%) for good; the yield rate is 80-90% (not including 90%) for poor; and the yield rate below 80% is poor.

[0100] B4, bonding strength index: The bonding strength index is excellent if the tape will not peel off after being torn off three times; it is good if there is slight edge peeling; it is poor if there is edge peeling; it is poor if there is peeling of the middle edge.

[0101] The performance test data of the palladium plating solution in Example 2 and Comparative Examples 5 to 8 evaluated according to the above evaluation method are shown in Table 2 below.

[0102] Table 2 Performance index test results of palladium plating solution in Example 2 and Comparative Examples 5 to 8

[0103] Test Group Stability index Appearance indicators Gold line indicator Binding index Example 2 excellent excellent excellent excellent Comparative Example 5 Difference Poor Poor Poor Comparative Example 6 good excellent good good Comparative Example 7 excellent Poor Poor good Comparative Example 8 excellent excellent good good

[0104] It can be seen from Table 2 that compared with the palladium plating solution in Example 2, the palladium plating solution in Comparative Example 5 lacks a composite complexing agent, and the stability index is reduced to poor, and the appearance index, the gold line index and the bonding index are all reduced to poor; the palladium plating solution in Comparative Example 6 lacks a stabilizer, and the stability index, the gold line index and the bonding index are all reduced to good; the palladium plating solution in Comparative Example 7 lacks an accelerator, and the appearance index and the gold line index are all reduced to poor, and the bonding index is reduced to good; the palladium plating solution in Comparative Example 8 lacks a uniforming agent, and the gold line index and the bonding index are all reduced to good. It can be seen that the components of the palladium plating solution in the present invention have a synergistic effect, and the lack of any component will cause a decrease in the overall performance.

[0105] Gold Plating Example

[0106] The gold plating solution in Example 3 and Comparative Examples 9 to 12 uses sodium hydroxide with a mass concentration of 5% and sulfuric acid solution with a volume concentration of 5% to adjust the pH to 7.5.

[0107] Example 3

[0108] This example provides a chemical gold plating solution, including the following components in mass concentrations: 2 g / L sodium gold sulfite, 60 mg / L pyrrole-1-propionic acid, 7.5 g / L histidine, 6 g / L thiosemicarbazide, 2 g / L methylpyrrole-2-carboxylate, 60 mg / L 2-piperidinemethanol, and the solvent is deionized water.

[0109] The pH of the chemical gold plating solution is 7.5.

[0110] When the chemical gold plating solution in this example is used, the copper substrate with the palladium plated layer in Example 2 needs to be subjected to chemical reduction gold plating at an operating temperature of 65° C. for 10 minutes, thereby forming a gold plated layer on the surface of the palladium plated layer.

[0111] Comparative Example 9

[0112] This example provides a chemical gold plating solution, including the following components in mass concentrations: 2 g / L sodium gold sulfite, 7.5 g / L histidine, 6 g / L thiosemicarbazide, 2 g / L methylpyrrole-2-carboxylate, 60 mg / L 2-piperidinemethanol, and the solvent is deionized water.

[0113] The pH of the chemical gold plating solution is 7.5.

[0114] When the chemical gold plating solution in this example is used, the copper substrate with the palladium plated layer in Example 2 needs to be subjected to chemical reduction gold plating at an operating temperature of 65° C. for 10 minutes, thereby forming a gold plated layer on the surface of the palladium plated layer.

[0115] Comparative Example 10

[0116] This example provides a chemical gold plating solution, including the following components in mass concentrations: 2 g / L sodium gold sulfite, 60 mg / L pyrrole-1-propionic acid, 7.5 g / L histidine, 6 g / L thiosemicarbazide, 2 g / L methylpyrrole-2-carboxylate, and the solvent is deionized water.

[0117] The pH of the chemical gold plating solution is 7.5.

[0118] When the chemical gold plating solution in this example is used, the copper substrate with the palladium plated layer in Example 2 needs to be subjected to chemical reduction gold plating at an operating temperature of 65° C. for 10 minutes, thereby forming a gold plated layer on the surface of the palladium plated layer.

[0119] Comparative Example 11

[0120] This example provides a chemical gold plating solution, including the following components in mass concentrations: 2 g / L sodium gold sulfite, 60 mg / L pyrrole-1-propionic acid, 7.5 g / L histidine, 6 g / L thiosemicarbazide, 60 mg / L 2-piperidinemethanol, and the solvent is deionized water.

[0121] The pH of the chemical gold plating solution is 7.5.

[0122] When the chemical gold plating solution in this example is used, the copper substrate with the palladium plated layer in Example 2 needs to be subjected to chemical reduction gold plating at an operating temperature of 65° C. for 10 minutes, thereby forming a gold plated layer on the surface of the palladium plated layer.

[0123] Comparative Example 12

[0124] This example provides a chemical gold plating solution, including the following components in mass concentrations: 2 g / L sodium gold sulfite, 60 mg / L pyrrole-1-propionic acid, 6 g / L thiosemicarbazide, 2 g / L methylpyrrole-2-carboxylate, 60 mg / L 2-piperidinemethanol, and the solvent is deionized water.

[0125] The pH of the chemical gold plating solution is 7.5.

[0126] When the chemical gold plating solution in this example is used, the copper substrate with the palladium plated layer in Example 2 needs to be subjected to chemical reduction gold plating at an operating temperature of 65° C. for 10 minutes, thereby forming a gold plated layer on the surface of the palladium plated layer.

[0127] The following gold plating index evaluation method was used to evaluate the performance of the chemical gold plating solution in Example 3 and Comparative Examples 9 to 12, specifically:

[0128] C1. Stability index: Excellent stability index refers to a sedimentation tank of half a year or more; good stability index refers to a sedimentation tank of four to six months (excluding June); poor stability index refers to a sedimentation tank of two to four months (excluding April); poor stability index refers to a sedimentation tank of less than two months (excluding two months).

[0129] C2. Color difference index: An excellent color difference index means that the coating is golden yellow with no color difference; a good color difference index means that the coating is golden yellow but has a slight color difference; a poor color difference index means that the coating has an obvious color difference but is not black; a poor color difference index means that there is a blackening phenomenon.

[0130] C3. Gold wire punching index: An excellent gold wire punching index means that twenty gold wires are punched continuously on the surface of the substrate, and the yield rate meets 100% for excellent; the yield rate is 90-100% (not including 100%) for good; the yield rate is 80-90% (not including 90%) for poor; and the yield rate below 80% is poor.

[0131] C4. Salt spray test indicators: The best salt spray test indicators are: test time is 48h, test temperature is 60℃, if there is no corrosion and blackening, it is excellent; if there are slight black spots on the edges, it is good; if there are obvious black spots in the middle of the edges, it is poor; if there are large areas of black spots, it is poor.

[0132] C5. Adhesion index: Excellent adhesion index means that the tape will not peel off after being torn three times; slight edge peeling is good; edge peeling is poor; and both edges in the middle are poor.

[0133] The performance index test results of the chemical gold plating solution in Example 3 and Comparative Examples 9 to 12 obtained by the above evaluation method are shown in Table 3 below:

[0134] Table 3 Performance index test results of gold plating solution in Example 3 and Comparative Examples 9 to 12

[0135]

[0136] It can be seen from Table 3 that compared with the gold plating solution in Example 3, the gold plating solution in Comparative Example 9 lacks an accelerator, and the color difference index, gold wire index and salt spray test index are all reduced to good; the gold plating solution in Comparative Example 10 lacks a stabilizer, and the stability index, color difference index, gold wire index, salt spray test index and bonding index are all reduced to good; the gold plating solution in Comparative Example 11 lacks a uniforming agent, and the color difference index, gold wire index, salt spray test index and bonding index are all reduced to good; the gold plating solution in Comparative Example 12 lacks a complexing agent, and the stability index, color difference index, gold wire index, salt spray test index and bonding index are all reduced to poor; it can be seen that the components of the gold plating solution in the present invention have a synergistic effect, and the lack of any component will cause a decrease in overall performance.

[0137] The above is a detailed description of the embodiments of the present invention, but the present invention is not limited to the above embodiments. Various changes can be made within the knowledge of ordinary technicians in the relevant technical field without departing from the purpose of the present invention. In addition, the embodiments of the present invention and the features in the embodiments can be combined with each other without conflict.

Claims

1. A chemical plating solution, characterized in that: Including nickel plating solution, palladium plating solution and gold plating solution; The nickel plating solution comprises the following components in mass concentrations: 4-6 g / L nickel salt, 3-7 g / L complexing agent, 20-60 mg / L stabilizer, 10-20 g / L reducing agent, 30-60 mg / L anti-pinhole agent, and 90-180 mg / L plating agent; The palladium plating solution comprises the following components in mass concentrations: palladium salt 0.8-1.2 g / L, complex complexing agent 6-12 g / L, accelerator 0.1-0.5 g / L, stabilizer 20-80 mg / L, reducing agent 10-20 g / L, and homogenizer 3-6 g / L; The gold plating solution comprises the following components in mass concentrations: 1-3 g / L of gold salt, 40-80 mg / L of accelerator, 5-10 g / L of complexing agent, 4-8 g / L of reducing agent, 30-90 mg / L of stabilizer and 1-3 g / L of homogenizing agent.

2. The chemical plating solution according to claim 1, characterized in that: The nickel plating solution has at least one of the following characteristics: a1: the plating agent includes tris(3-hydroxypropyltriazolemethyl)amine; a2: the anti-pinhole agent includes bis(2-dimethylaminoethyl) ether; a3: the complexing agent includes 3,5-pyridinedicarboxylic acid; a4: the stabilizer includes 2-piperidinol; a5: the reducing agent includes at least one of sodium hypophosphite and potassium hypophosphite; a6: The nickel salt is selected from at least one of nickel sulfate, nickel chloride, nickel nitrate, nickel acetate, nickel citrate, nickel fluoroborate and nickel sulfamate.

3. The chemical plating solution according to claim 1, characterized in that: The palladium plating solution has at least one of the following characteristics: b1: the palladium salt is selected from at least one of tetraamminepalladium sulfate, palladium chloride, palladium nitrate, dichlorotetraamminepalladium, dibromotetraamminepalladium, diiodidetetraamminepalladium, dinitritetetraamminepalladium, dinitratetetraamminepalladium, disulfitetetraamminepalladium, dinitrotetraamminepalladium, dichlorodiamminepalladium, dibromodiamminepalladium, diiodidediamminepalladium, dinitritediamminepalladium, dinitratediamminepalladium, disulfitediamminepalladium, disulfatediamminepalladium, and dinitrodiamminepalladium; b2: the composite complexing agent comprises a mixture of at least one selected from ethylenediamine, propylenediamine, butylenediamine and bis-3-aminopropyl-1,3-propylenediamine; b3: the accelerator includes 4-piperidinamide; b4: the reducing agent is at least one selected from the group consisting of sodium formate, potassium formate, sodium acetate, potassium acetate, sodium propionate, potassium propionate, sodium butyrate and potassium butyrate; b5: the stabilizer includes at least one of 5-methylindole-2-methyl ester, 5-methylindole-2-carboxylic acid methyl ester, 5-methylindole-2-carboxylic acid propyl ester, 5-methylindole-2-carboxylic acid butyl ester, and 5-methylindole-2-carboxylic acid pentyl ester; b6: The homogenizer includes at least one of 2-methylthiazole-5-carboxylic acid, 2-methylthiazole-5-acetic acid, and 4-methylthiazole-5-propionic acid.

4. The chemical plating solution according to claim 1, characterized in that: The gold plating solution has at least one of the following characteristics: c1: the gold salt is at least one selected from the group consisting of gold sulfite, gold chloroate, gold thiosulfate, and gold thiomalate; c2: the reducing agent includes thiosemicarbazide; c3: the accelerator comprises at least one of pyrrole-1-propionic acid, pyrrole-1-butyric acid, pyrrole-1-carboxylic acid, pyrrole-1-acetic acid, and pyrrole-1-valeric acid; c4: the homogenizer includes at least one of methylpyrrole-2-carboxylate, ethylpyrrole-2-carboxylate, butylpyrrole-2-carboxylate, propylpyrrole-2-carboxylate, and pyrrole-2-carboxylate; c5: the stabilizer comprises at least one of 2-piperidinemethanol, 2-piperidineethanol, 2-piperidinepropanol and 2-piperidinebutanol; c6: The complexing agent includes histidine.

5. The chemical plating solution according to claim 1, characterized in that: In the palladium plating solution, the composite complexing agent is a mixture of ethylenediamine and bis(3-aminopropyl)-1,3-propylenediamine in a mass ratio of (1-10):

1.

6. The chemical plating solution according to claim 1, characterized in that: At least one of the nickel plating solution, the palladium plating solution and the gold plating solution uses water as a solvent.

7. The chemical plating solution according to any one of claims 1 to 6, characterized in that: The pH of the nickel plating solution is 4.4-4.8; And / or, the pH of the palladium plating solution is 6.2-6.8; And / or, the pH value of the gold plating solution is 7.2-7.

8.

8. A chemical plating method, characterized in that: The following steps are involved: The workpiece to be plated is immersed in the chemical plating solution according to any one of claims 1 to 7 and heated to perform chemical plating to form a plating layer on the surface of the workpiece to be plated.

9. The chemical plating method according to claim 8, characterized in that: The chemical plating method comprises the following steps: The workpiece to be plated is immersed in a nickel plating solution at a temperature of 70 to 80° C. to perform chemical plating to form a nickel plating layer on the surface of the workpiece to be plated; and / or, Immersing the workpiece to be plated in a palladium plating solution at a temperature of 58 to 68° C. for chemical plating to form a palladium plating layer on the surface of the workpiece to be plated; and / or, The workpiece to be plated is immersed in a gold plating solution at a temperature of 60 to 70° C. for chemical plating to form a gold plating layer on the surface of the workpiece to be plated.

10. Use of the chemical plating solution according to any one of claims 1 to 7 in the field of metal plating of products.

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