Thiocarbamate compound, preparation method, application and electroplating solution

Abstract

The invention relates to the technical field of fine chemicals, in particular to a thiocarbamate compound, a preparation method, application and an electroplating solution. The structural formula of the compound is shown in the formula (I). The compound has a unique thioester structure, has excellent auxiliary gloss and leveling performance, not only effectively broadens the application scene of the organic copper electroplating additive, but also can remarkably reduce the quality hidden danger of a plated part caused by the lack of a leveling agent in actual production, and is simple and efficient in synthesis process, controllable in operation and suitable for large-scale mass production requirements. And the method has outstanding industrial application value.

Description

Technical Field

[0001] This invention relates to the field of fine chemicals, and in particular to a thiocarbamate compound, its preparation method, application, and electroplating solution. Background Technology

[0002] Traditional brighteners in acidic copper plating organic additives mainly include polydisulfide dipropane sulfonic acid and its salts, 3-mercaptopropane sulfonic acid and its salts, N,N-dimethyldithioaminopropane sulfonic acid and its salts, thiazoline dithiopropane sulfonic acid and its salts, 2-mercapto-5-benzimidazole sulfonic acid and its salts, and polydisulfide diethane sulfonic acid and its salts. These brighteners generally contain mercapto, thioether, or dithioether structures. Some products (such as sodium N,N-dimethyldithioaminopropane sulfonate and its salts, and thiazoline dithiopropane sulfonic acid and its salts) also contain nitrogen and sulfur elements. In acidic copper plating solutions, they are usually used in combination with leveling agents at a concentration of 1-5 mg / L. Although the amount added is small, it is crucial to the quality of the plating layer.

[0003] With the development of the electronics industry, electroplating process conditions place higher demands on the adaptability of additive structures, and traditional brighteners can no longer fully meet industry needs. Especially in unstable production scenarios such as the initial setup of production lines and resumption of work after holidays, plating bath imbalances are prone to occur, leading to excessively low levels of brighteners or leveling agents. Because traditional brighteners lack structures related to leveling functions, and the dithioester structures of some nitrogen-containing products are too reactive, they can mask the effects of nitrogen-containing groups, failing to achieve both brightening and leveling effects at the single-molecule leveling level. When the leveling agent content is extremely low or even undetectable due to factors such as line stoppage and adsorption, whitening is likely to occur in low-current areas of electroplating, and there is a significant difference between the plating lattice and that of high-current areas. Therefore, developing novel electroplating additives to address abnormal problems in various practical applications has become an urgent industry need.

[0004] Chinese invention patent application CN108950670A discloses a PCB electroplating solution. By using a neutral electroplating solution, including components such as methanesulfonic acid and tin methanesulfonate, it solves the problems of damage and pollution caused by the target mounting fixtures in the prior art, achieving an environmentally friendly and zero-emission copper / tin / nickel layer removal effect, suitable for conventional stainless steel mounting fixtures. Chinese invention patent application CN112941575A discloses a copper salt weakly alkaline electroplating solution for PCB hole metallization and its application. Through a low-concentration copper salt weakly alkaline electroplating solution with citrate complex coordination, it solves the problems of strong dispersion dependence in acidic copper plating processes and insufficient application of alkaline copper plating solutions, achieving efficient and low-cost PCB hole metallization with a fine and dense copper layer and strong dispersion ability, suitable for uniform thickening of PCB through-hole electroplating; however, these prior art technologies have not solved the aforementioned technical problems.

[0005] Against this backdrop, there is an urgent need to provide a new type of electroplating additive that can meet the requirements of PCB (printed circuit board) electroplating and effectively inhibit the deterioration of plated parts quality due to imbalance of leveling agents and other additives. Summary of the Invention

[0006] To address the structural defects of existing sulfur / nitrogen-containing organic small-molecule electroplating additives, this invention provides a thiocarbamate compound with a novel compound structure. When used as an electroplating additive, this compound solves the technical problem of poor coating quality caused by imbalances in leveling agents under various influences. Even in electroplating bath systems without added leveling agents, it ensures excellent coating lattice and appearance quality, effectively avoiding coating reliability issues.

[0007] The first aspect of this invention provides a thiocarbamate compound, the structural formula of which is shown in formula (I): Equation (Ⅰ) In Equation (I), the structural formula of R is shown in Equation (II), and the structural formula of R' is shown in Equation (III); Formula (II) R1 and R2 are independently selected from one of hydrogen, methyl, ethyl, n-propyl, n-butyl, tert-butyl, isopropyl, and phenyl; and R1 and R2 are not both hydrogen. Formula (III) Where m = 2-4; M is hydrogen or a metal ion.

[0008] Optionally, the metal ion is Na. + or K + .

[0009] Traditional brighteners in existing acidic copper plating organic additives (such as sodium polydithiopropane sulfonate and sodium N,N-dimethyldithioaminopropane sulfonate) are limited by their structure and cannot simultaneously achieve both brightening and leveling effects. Furthermore, when the leveling agent is unbalanced (e.g., during the initial stage of production line plating or after a holiday resumption of work), quality problems such as whitening in low-current areas, abnormal crystal lattice, and rough orifices are easily caused. This invention uses a novel sulfur- and nitrogen-containing compound with a thiocarbamate structure (structural formulas shown in formulas (I) to (III)) as an electroplating copper additive. This achieves good gloss and smooth orifice morphology even in the absence of a leveling agent or without adjustment of the plating solution. The novel compound exhibits a uniform crystal lattice, effectively preventing coating reliability issues. This is because its molecular structure combines N-substituted carbamoyl groups and thioether groups. The N-substituted carbamoyl groups regulate the deposition rate of copper ions during electroplating, enabling precise control of coating growth. The thioethers, on the other hand, act as a gloss-enhancing agent. The synergistic effect of these two components not only compensates for the lack of leveling function in traditional brighteners but also reduces functional coverage issues caused by excessive molecular activity through structural optimization. This ensures coating quality even in abnormal scenarios such as the absence of leveling agents. Furthermore, its simple synthesis process and suitability for mass production provide new structural options and optimization solutions for electroplating additives.

[0010] Optionally, the raw materials for preparing the compound include: the compound shown in formula (Ⅳ), an organic base, the compound shown in formula (Ⅴ), and a solvent.

[0011] Formula (Ⅳ) Formula (V) Wherein, X is a halogen; optionally, the halogen is derived from Cl or Br.

[0012] Optionally, the molar ratio of the compound shown in formula (Ⅳ), the organic base, and the compound shown in formula (Ⅴ) is 1:(1.05-1.2):(1.01-1.1); further optionally, it is 1:1.1:1.05.

[0013] The organic base may include tri-n-butylamine, triethylamine, N,N-diisopropylethylamine (DIPEA), pyridine, etc.; triethylamine may be a further alternative.

[0014] The solvent may include one or more combinations of water, acetonitrile, tetrahydrofuran, DMF (N,N-dimethylformamide), DMSO (dimethyl sulfoxide), and DMF (N-methylpyrrolidone). This invention does not impose any particular limitation on the solvent, as long as it is capable of dissolving the compound shown in formula (Ⅳ).

[0015] In some embodiments, the solvent is water and tetrahydrofuran; optionally, the volume ratio of water to tetrahydrofuran is (1-4):(5-10); further optionally, it is 3:7.

[0016] A second aspect of the present invention provides a method for preparing a thiocarbamate compound, wherein the preparation steps of the compound include: The compound shown in formula (Ⅳ) was dissolved in a solvent and a pre-reaction was carried out by adding an organic base; The compound shown in formula (V) was added to the reaction to obtain the crude product; The crude product was post-processed to obtain the thiocarbamate compound represented by formula (Ⅰ).

[0017] Optionally, when M is hydrogen (the compound of formula (IV) is an acid), the compound of formula (IV) is mixed with a strong base for neutralization reaction before adding the organic base.

[0018] Examples of strong bases include sodium hydroxide and potassium hydroxide.

[0019] Optionally, the molar amount of the strong base added is the same as the molar amount of the sulfonic acid group in the compound shown in formula (Ⅳ).

[0020] Optionally, the pre-reaction temperature is 20-80℃ and the reaction time is 10-60 min; more preferably, it is 15-30 min.

[0021] Optionally, the reaction temperature is 20-80℃ and the reaction time is 1-8h; more preferably, it is 2-4h.

[0022] Optionally, the post-processing steps include: performing vacuum distillation on the crude product, dissolving it in water after vacuum distillation, mixing it with alcohol, separating the liquid phase, collecting the aqueous phase, and obtaining an aqueous solution of thiocarbamate compounds; and recrystallizing the aqueous solution of the thiocarbamate compounds to obtain pure thiocarbamate compounds.

[0023] In some embodiments, the amount of alcohol added is 30-50% of the volume of the solution after dissolution in water.

[0024] In some embodiments, the preparation steps of the compound include: S1. Place the compound shown in formula (Ⅳ) in a reaction vessel, add solvent to dissolve it, add organic base, stir and heat to 20-80℃ for pre-reaction for 15-30 min; S2. Slowly add the compound shown in formula (V) into the reactor and maintain the same temperature as the pre-reaction for 1-8 hours to obtain the crude product; S3. The crude product is subjected to vacuum distillation. After vacuum distillation, water is added to dissolve the product, alcohol is added and stirred, and then the mixture is separated. The aqueous phase is collected to obtain an aqueous solution of thiocarbamate compounds. The aqueous solution of the thiocarbamate compounds is recrystallized to obtain pure thiocarbamate compounds.

[0025] In some implementations, aqueous solutions of thiocarbamate compounds can be directly used for mass production and application in downstream scenarios; the actual dosage can be determined by calculating the effective content of the thiocarbamate compound.

[0026] Optionally, the compound shown in formula (V) is added by dropwise addition, with the addition time controlled to be 20-40 min.

[0027] In some embodiments, the reaction temperature is 20-30°C and the reaction time is >4 hours.

[0028] In some embodiments, the reaction temperature is 35-80°C and the reaction time is 1-6 hours.

[0029] In some embodiments, the alcohol may include methanol, ethanol, isopropanol, etc.

[0030] A third aspect of the present invention provides an application of the thiocarbamate compound described above, wherein the thiocarbamate compound is used in the field of printed circuit boards.

[0031] A fourth aspect of the present invention provides an electroplating solution containing an electroplating additive, wherein the electroplating additive is a thiocarbamate compound as described above.

[0032] The thiocarbamate compounds of this invention possess both excellent auxiliary gloss and leveling properties, which not only broadens the application scenarios of organic electroplating copper additives, but also significantly reduces the potential quality risks of plated parts caused by the lack of leveling agents in actual production, thereby improving the quality of plated parts.

[0033] Optionally, the electroplating solution does not contain a leveling agent.

[0034] Optionally, the amount of the electroplating additive added to the electroplating solution is 0.5-10 mg / L; more preferably 1.0-5.0 mg / L; examples include 1.0 mg / L, 2.0 mg / L, 3.0 mg / L, 4.0 mg / L, and 5.0 mg / L.

[0035] Beneficial effects: This invention provides a thiocarbamate compound, its preparation method, application, and electroplating solution, which has the following advantages: (1) This invention provides a novel sulfur- and nitrogen-containing organic molecule with a molecular structure that is different from traditional electroplating additives, providing a new choice of structural molecules for the field of copper electroplating and other potential application scenarios.

[0036] (2) When the novel compound described in this invention is used as an electroplating additive, even if no leveling agent is added to the system, a regular electroplating lattice structure can still be obtained, the coating has excellent appearance performance, no whitening of the pore openings, and can also play an auxiliary role in improving the gloss of the coating.

[0037] (3) When the novel compound described in this invention is used as an auxiliary brightener in electroplating additives, it can be used as a fault-tolerant additive in continuous production processes; even if the electroplating solution is not adjusted in real time, it can effectively avoid reliability defects in the copper plating layer and ensure the stability of the plating performance.

[0038] (4) The raw materials for preparing the compounds of the present invention are readily available, the synthesis process is simple and efficient, the operation is controllable, and they can be used directly as additives in industrial production without purification, which is suitable for large-scale mass production and has outstanding industrial application value. Attached Figure Description

[0039] Figure 1 Example 1: 1H NMR spectrum of pure thiocarbamate compounds; Figure 2 Example 1: Infrared spectrum of pure thiocarbamate compounds; Figure 3 Example 2: 1H NMR spectrum of pure thiocarbamate compounds; Figure 4 Example 2: Infrared spectrum of pure thiocarbamate compounds; Figure 5 Electroplating effect diagram of Application Example 1; Figure 6 Electroplating effect diagram of application example 2; Figure 7 Electroplating effect diagram of application example 3; Figure 8 The electroplating effect diagram of Example 4; Figure 9 The electroplating effect diagram of Example 5; Figure 5-9 In the middle: the top left sub-image corresponds to the Hull tank electroplating effect with 1.0 mg / L electroplating additive, and the top right sub-image corresponds to the Hull tank electroplating effect with 5.0 mg / L electroplating additive; the bottom left sub-image corresponds to the Haring tank electroplating effect with 5.0 mg / L electroplating additive, and the bottom right sub-image corresponds to the Haring tank electroplating effect with 5.0 mg / L electroplating additive. Detailed Implementation

[0040] Unless otherwise specified, all raw materials, equipment and other consumables involved in this invention are commercially available.

[0041] Example 1 This embodiment provides a thiocarbamate compound and its preparation method. The structural formula of the compound is as follows: Its name is sodium 3-(diethylcarbamoylthio)propane-1-sulfonate.

[0042] The raw materials for preparing the compound include: 0.1 mol sodium 3-mercaptopropanesulfonate, 0.11 mol triethylamine, 0.105 mol N,N-diethylchloroformamide, and 100 mL solvent (30 mL water and 70 mL tetrahydrofuran).

[0043] The preparation steps of the compound include: S1. Place sodium 3-mercaptopropanesulfonate in a 500 mL reactor, add solvent to dissolve it, add triethylamine, stir and heat to 35 °C for pre-reaction for 30 min; S2. N,N-diethylchloroformamide was slowly added dropwise to the reaction vessel (completed in 30 min), and the reaction was maintained at 35 °C for 4 h to obtain the crude product; S3. Post-processing: The crude product was subjected to vacuum distillation to remove the solvent. After vacuum distillation, 50 mL of water was added to dissolve the product, and 50 mL of ethanol was added to mix and stir. After stirring for 5 min, the mixture was allowed to stand and separated. The aqueous phase was collected to obtain an aqueous solution of thiocarbamate compounds. The aqueous solution of the thiocarbamate compounds was recrystallized (using water as the solvent) to obtain 22.63 g of pure thiocarbamate compounds; yield 81.6%.

[0044] Example 1: The 1H NMR spectrum of the pure thiocarbamate compound is shown in [reference needed]. Figure 1 Infrared spectrum (see) Figure 2 .

[0045] Example 2 This embodiment provides a thiocarbamate compound and its preparation method. The structural formula of the compound is as follows: Its name is sodium 3-(dimethylcarbamoylthio)propane-1-sulfonate.

[0046] The raw materials for preparing the compound include: 0.1 mol sodium 3-mercaptopropanesulfonate, 0.105 mol triethylamine, 0.1 mol N,N-dimethylchloroformamide, and 100 mL solvent (30 mL water and 70 mL tetrahydrofuran).

[0047] The preparation steps of the compound include: S1. Place sodium 3-mercaptopropanesulfonate in a 500 mL reactor, add solvent to dissolve it, add triethylamine, stir and heat to 35 °C for pre-reaction for 30 min; S2. Add N,N-dimethylchloroformamide to the reaction vessel and maintain the reaction temperature at 35°C for 3 hours to obtain the crude product; S3. Post-processing: The crude product was subjected to vacuum distillation to remove the solvent. After vacuum distillation, 50 mL of water was added to dissolve the product, and 50 mL of ethanol was added to mix and stir. After stirring for 5 min, the mixture was allowed to stand and separated. The aqueous phase was collected to obtain an aqueous solution of thiocarbamate compounds. The aqueous solution of the thiocarbamate compounds was recrystallized to obtain 20.6 g of pure thiocarbamate compounds; yield 82.6%.

[0048] Example 2: The 1H NMR spectrum of the pure thiocarbamate compound is shown in [reference needed]. Figure 3 Infrared spectrum (see) Figure 4 .

[0049] Example 3 This embodiment provides a thiocarbamate compound and its preparation method, with the specific implementation method being the same as in Example 1; the difference is that sodium 3-mercaptopropanesulfonate is replaced with sodium 2-mercaptoethanesulfonate (i.e., m=2), and the amount added remains unchanged at 0.1 mol.

[0050] Example 3: The yield of pure thiocarbamate compounds was 83.2%.

[0051] Example 4 This embodiment provides a thiocarbamate compound and its preparation method, with the specific implementation method being the same as in Example 1; the difference is that: sodium 3-mercaptopropanesulfonate is replaced with sodium 2-mercaptoethanesulfonate (i.e., m=2), and the amount added remains unchanged at 0.1 mol; N,N-diethylchloroformamide is replaced with N,N-dimethylchloroformamide (i.e., R1 and R2 are both methyl), and the amount added remains unchanged at 0.105 mol.

[0052] Example 4: The yield of pure thiocarbamate compounds was 81.5%.

[0053] Example 5 This embodiment provides a thiocarbamate compound and its preparation method, with the specific implementation method being the same as in Example 1; the difference is that N,N-diethylchloroformamide is replaced with N,N-diphenylchloroformamide (i.e., R1 and R2 are both phenyl), and the amount added remains unchanged at 0.105 mol; the volume ratio of tetrahydrofuran to water in the solvent is 7:2 (the solvent volume is kept at 100 mL).

[0054] Example 5: The yield of pure thiocarbamate compounds was 78.1%.

[0055] Example 6 This embodiment provides a thiocarbamate compound and its preparation method, with the specific implementation method being the same as in Example 1; the difference is that the reaction conditions for step S2 are: 20°C for 16 hours.

[0056] Example 6: The yield of pure thiocarbamate compounds was 82.0%.

[0057] Example 7 This embodiment provides a thiocarbamate compound and its preparation method, with the specific implementation method being the same as in Example 1; the difference is that the reaction conditions for step S2 are: reaction at 80°C for 4 hours.

[0058] Example 7: The yield of pure thiocarbamate compounds was 80.1%.

[0059] Example 8 This embodiment provides a thiocarbamate compound and its preparation method, with the specific implementation method being the same as in Example 1; the difference is that the reaction conditions for step S2 are: 80°C for 1 hour.

[0060] Example 8: The yield of pure thiocarbamate compounds was 79.2%.

[0061] Comparative Example 1 This comparative example provides a thiocarbamate compound and its preparation method, with the specific implementation method being the same as in Example 1; the difference being that the reaction conditions for step S2 are: 20°C for 4 hours.

[0062] The yield of pure thiocarbamate compounds in Comparative Example 1 was 66.2%.

[0063] Based on the test results of Examples 1-8 and Comparative Example 1, the optimal synthesis conditions for the novel compound of this invention are as follows: the preferred reaction temperature is 20-80℃, and the preferred reaction time is 1-6 h (when the reaction temperature is 20℃, the reaction time needs to be >4 h). The yield results show that the control of reaction temperature and time is crucial to the selectivity and conversion rate: too low a temperature will significantly reduce the reaction rate, requiring a longer reaction time to achieve the target yield, thus affecting production efficiency; while too high a temperature can shorten the reaction cycle, it will induce side reactions, leading to a greater tendency for the acyl chloride groups in the raw materials to hydrolyze, resulting in a slight decrease in the yield of the target product.

[0064] Comparative Example 2 Sodium polydisulfide dipropane sulfonate, with the following structural formula: .

[0065] Comparative Example 3 Sodium N,N-dimethyldithioaminopropane sulfonate, with the structural formula: .

[0066] Application Example 1 An electroplating solution, the formula of which is as follows: Copper sulfate pentahydrate 65 g / L; Sulfuric acid 235 g / L; Hydrochloric acid 66 mg / L Electroplating additives 1.0 mg / L or 5.0 mg / L (two sets of experiments); Inhibitor 600ppm.

[0067] The electroplating additive in the electroplating solution is a thiocarbamate compound prepared in Example 1 above.

[0068] The inhibitor is poly(ethylene glycol-ran-polypropylene glycol) monobutyl ether, CAS number 9038-95-3, with an average molecular weight of 1500; it is derived from Maclean's.

[0069] Application Example 2 An electroplating solution, the specific implementation method is the same as in Application Example 1; the difference is that the electroplating additive in the electroplating solution is a thiocarbamate compound obtained in Example 2 above.

[0070] Application Example 3 An electroplating solution, the specific implementation method is the same as in application example 1; the difference is that the electroplating additive in the electroplating solution is a thiocarbamate compound obtained in example 3 above.

[0071] Application Example 4 An electroplating solution, the specific implementation method is the same as in Application Example 1; the difference is that the electroplating additive in the electroplating solution is a thiocarbamate compound prepared in Comparative Example 2 above.

[0072] Application Example 5 An electroplating solution, the specific implementation method is the same as in Application Example 1; the difference is that the electroplating additive in the electroplating solution is a thiocarbamate compound prepared in Comparative Example 3 above.

[0073] Performance testing Electroplating tests were conducted using the electroplating solutions from Application Examples 1-5. The test methods are as follows; the test results are shown in Table 1 and... Figure 5-9 .

[0074] Test System 1: Electroplating test was conducted using a Hull tank plate. The electroplating material was a brass sheet with dimensions of 100mm×65mm×0.5mm, and electroplating was performed at a current of 2A for 5 minutes.

[0075] Test System 2: Electroplating test was conducted using Harlem stencils. The electroplating material was a PCB component with holes and a conductive thin layer (size 150mm×60mm×1.5mm), and electroplating was performed at a current of 20ASF for 30 minutes.

[0076] Table 1

[0077] From Table 1 and Figure 5-9 The test results show that, in the absence of a leveling agent in the electroplating solution system, the thiocarbamate compounds prepared in Examples 1-3 of this invention impart excellent gloss to the plated parts under both high and low concentration conditions. In contrast, the comparative compound used in Examples 4-5 exhibited haze in the lower regions and rough, uneven orifices under both high and low concentration conditions. Furthermore, the Hull tank using the compound from the examples showed good gloss in the lower regions, and the orifices of the PCB plated parts were normal and without roughness. These test results demonstrate that the novel compounds prepared in this invention can effectively prevent PCB plated part quality problems caused by the absence of a leveling agent in practical applications, thereby improving the quality of the plated parts.

[0078] The embodiments and descriptions above are merely illustrative of the principles and specific implementations of the present invention. Various changes and modifications may be made to the present invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed.

Claims

1. A thiocarbamate compound, characterized in that, The structural formula of the compound is shown in formula (Ⅰ): Equation (I) In Equation (I), the structural formula of R is shown in Equation (II), and the structural formula of R' is shown in Equation (III); Formula (II) R1 and R2 are independently selected from one of hydrogen, methyl, ethyl, n-propyl, n-butyl, tert-butyl, isopropyl, and phenyl; and R1 and R2 are not both hydrogen. Formula (III) Where m = 2-4; M is hydrogen or a metal ion.

2. The thiocarbamate compound according to claim 1, characterized in that, The raw materials for preparing the compound include: the compound shown in formula (Ⅳ), an organic base, the compound shown in formula (Ⅴ), and a solvent; Formula (Ⅳ) Formula (V); Where X is a halogen.

3. The thiocarbamate compound according to claim 1, characterized in that, The molar ratio of the organic base to the compound shown in formula (Ⅳ) is 1:(1.05-1.2).

4. A method for preparing a thiocarbamate compound according to claim 2 or 3, characterized in that, The preparation steps of the compound include: The compound shown in formula (Ⅳ) was dissolved in a solvent and a pre-reaction was carried out by adding an organic base; The compound shown in formula (V) was added to the reaction to obtain the crude product; The crude product was post-processed to obtain the thiocarbamate compound represented by formula (Ⅰ).

5. The method for preparing thiocarbamate compounds according to claim 4, characterized in that, The pre-reaction temperature is 20-80℃, and the reaction time is 10-60 min.

6. The method for preparing thiocarbamate compounds according to claim 5, characterized in that, The reaction temperature is 20-80℃, and the reaction time is 1-8h.

7. The method for preparing thiocarbamate compounds according to claim 4, characterized in that, The post-processing steps include: distilling the crude product under reduced pressure, dissolving it in water after distillation, mixing it with alcohol, separating the liquid phase, collecting the aqueous phase, and obtaining an aqueous solution of thiocarbamate compounds; and recrystallizing the aqueous solution of the thiocarbamate compounds to obtain pure thiocarbamate compounds.

8. An application of a thiocarbamate compound according to any one of claims 1-3, characterized in that, The thiocarbamate compounds are used in the field of printed circuit boards.

9. An electroplating solution, characterized in that, The electroplating solution contains an electroplating additive, which is a thiocarbamate compound as described in any one of claims 1-3.

10. The electroplating solution according to claim 9, characterized in that, The amount of the electroplating additive added to the electroplating solution is 0.5-10 mg / L.

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