An acidic copper plating brightener and its preparation method

Abstract

This application relates to the field of electroplating technology, and more particularly to an acidic copper plating brightener and its preparation method. An acidic copper plating brightener, by weight, comprises the following raw materials: 25-30 parts brightener, 6-8 parts leveling agent, 40-50 parts wetting agent, 7-10 parts hydroxyethyl cellulose, 8-12 parts collagen, and 900-930 parts deionized water. The acidic copper plating brightener of this application has excellent technical effects and can be widely used in the field of copper electroplating to improve the quality of the electroplated copper layer, including gloss, tensile strength, elongation, hole-filling efficiency, uniform plating ability, and through-hole deep plating ability, thus meeting the requirements for the conductivity of through-holes in circuit boards.

Description

Technical Field

[0001] This application relates to the field of electroplating technology, and in particular to an acidic copper plating brightener and its preparation method. Background Technology

[0002] In today's rapidly evolving information age, electronic products are becoming increasingly smaller and more functionally diverse, leading to a continuous increase in the wiring density of printed circuit boards (PCBs). High-density interconnect (HDI), build-up, and blind via technologies are effective ways to improve PCB wiring density during manufacturing. However, for HDI boards with blind via designs, customers often require copper plating to fill the vias, ensuring the reliability of interlayer interconnects through copper plating. Therefore, the performance of copper plating additives faces significant challenges.

[0003] Current circuit board hole metallization processes require sufficient adhesion between the metal layer and the substrate to ensure good circuit interconnect performance and withstand thermal shocks and mechanical stresses that may occur during manufacturing and use. Existing acidic copper plating brighteners are simply insufficient to meet the demands of high-performance circuit board manufacturing. Summary of the Invention

[0004] The purpose of this application is to address the shortcomings of the current technology by providing an acidic copper plating brightener and its preparation method. The electroplated copper layer obtained by using the acidic copper plating brightener prepared in this application has excellent gloss, tensile strength and elongation, as well as high hole filling efficiency, excellent uniform plating ability and through-hole deep plating ability, thus meeting the requirements of the through-hole conductivity of circuit boards.

[0005] In a first aspect, this application provides an acidic copper plating brightener, employing the following technical solution:

[0006] An acidic copper plating brightener, by mass parts, comprises the following raw materials: 25-30 parts brightener, 6-8 parts leveling agent, 40-50 parts wetting agent, 7-10 parts hydroxyethyl cellulose, 8-12 parts collagen, and 900-930 parts deionized water.

[0007] By adopting the above technical solution, the acidic copper plating brightener of this application comprises the following components: brightener, leveling agent, wetting agent, hydroxyethyl cellulose, collagen, and deionized water. These components work synergistically to give the electroplated copper layer excellent gloss, tensile strength, and elongation, as well as high through-hole filling efficiency, excellent uniform plating ability, and excellent through-hole plating depth. Brightener: Controls the nucleation and growth of the copper layer during copper electrodeposition, improves gloss by refining the grains, and makes the plating surface smoother and denser. Leveling agent (pyridine benzyl ammonium chloride): Used in the copper electroplating process, the nitrogen-containing aromatic heterocycles are more prone to electrophilic reactions, making the compound easier to adsorb onto the cathode surface, improving through-hole filling efficiency, excellent uniform plating ability, and excellent through-hole plating depth. Wetting agent: Different wetting agents have different inhibitory abilities on the copper plate surface. By compounding multiple wetting agents with synergistic effects, the copper plating grains are refined more uniformly, resulting in uniform, dense, and fine grains. Hydroxyethyl cellulose and collagen: synergistic effect enhances the gloss, tensile strength, and elongation of the electroplated copper layer. In summary, the acidic copper plating brightener of this application, through the synergistic effect of its components, can obtain an electroplated copper layer with excellent performance, meeting the conductivity requirements of through-hole plating in circuit boards.

[0008] Preferably, the mass ratio of the hydroxyethyl cellulose to the collagen is 1:1.

[0009] By adopting the above technical solutions, hydroxyethyl cellulose (HEC) is a water-soluble polymer with good film-forming properties and stability. During electroplating, it can act as an additive to help form a uniform and smooth coating. Simultaneously, it can also act as a wetting agent, reducing surface tension and improving the wettability of the plating solution, thereby improving the adhesion and coverage of the coating. Collagen is a natural high-molecular-weight protein with good biocompatibility and bioactivity. During electroplating, it can act as a brightener and leveling agent, improving the gloss and smoothness of the coating. Furthermore, collagen has excellent tensile strength and elongation, which can improve the mechanical properties of the coating. The synergistic effect between HEC and collagen is mainly reflected in the following aspects: Complementarity: HEC primarily provides film-forming properties and stability, while collagen primarily provides brightness and leveling properties. Using them together can fully leverage their respective advantages to achieve better electroplating results. Interaction: HEC and collagen may interact in solution to form a complex. This complex may have better properties, such as higher stability and stronger adhesion, thereby further improving the quality of the coating. Synergistic Effect: Hydroxyethyl cellulose and collagen may have a synergistic effect during electroplating, jointly influencing the copper electrodeposition process. For example, they may jointly regulate the nucleation and growth process of the copper layer, refine the grains, and improve gloss; or they may jointly improve the wettability of the plating solution, increasing the filling efficiency and plating uniformity. In summary, the synergistic effect of hydroxyethyl cellulose and collagen in acidic copper plating brighteners helps improve the quality of electroplated copper layers, achieving excellent gloss, tensile strength and elongation, as well as efficient filling and through-hole plating capabilities.

[0010] Preferably, the brightener is composed of sodium polydithiopropane sulfonate, sodium thiazolinyl dithiopropane sulfonate, and methylene blue in a mass ratio of 5:3:2.

[0011] By employing the above technical solutions, the brightener's role is to control the nucleation and growth of the copper layer during copper electrodeposition. In the instantaneous nucleation process controlled by three-dimensional diffusion, it refines the grains, enhances gloss, and makes the coating surface smoother and denser. Sodium polydithiopropane sulfonate (SPS) is a commonly used brightener. It can adsorb onto active sites on the copper surface, inhibiting the copper deposition rate, thereby refining the copper grains and improving the brightness and smoothness of the coating. Sodium thiazolinyl dithiopropane sulfonate (MPS) is a leveling agent. It can form a complex with SPS, jointly adsorbing onto active sites on the copper surface, further inhibiting the copper deposition rate, making the copper grains even finer, and improving the brightness and smoothness of the coating. Methylene blue (MB) is a dye that can form a ternary complex with SPS and MPS, jointly adsorbing onto active sites on the copper surface, further inhibiting the copper deposition rate, making the copper grains even finer, and improving the brightness and smoothness of the coating. Simultaneously, MB also has a certain antioxidant effect, protecting the copper coating from oxidation. Through the synergistic effect of these three substances, the copper electrodeposition process can be effectively controlled to obtain an electroplated copper layer with excellent gloss, tensile strength and elongation, which meets the requirements of the through-hole conductivity of circuit boards.

[0012] Preferably, the preparation method of the sodium polydisulfide dipropane sulfonate includes the following steps:

[0013] S41. Add 6L of methanol and 1824g of thiourea to an enamel kettle and stir until homogeneous. Cool the temperature to 20℃ and slowly add 2440g of 1,3-propanesulfonyl lactone, controlling the adding temperature at 25-30℃. After the addition is complete, continue the reaction at 32℃ for 4-5 hours. Centrifuge and dry to obtain 3-isothiourea propanesulfonic acid.

[0014] S42. Add 1980g of 3-isothiourea propanesulfonic acid to an enamel-lined autoclave and add it to 8.3L of 26% ammonia solution. Heat to 60°C with stirring until the salt dissolves. Cool to 13-15°C and maintain for 1 hour. Evaporate using a rotary evaporator until a solid precipitates. Cool to 13-15°C and recrystallize with a chloroform and isopropanol mixture (mass ratio 1:1.3) to obtain ammonium 3-mercaptopropanesulfonate. S43. Dissolve 1590g of ammonium 3-mercaptopropanesulfonate in 4L of distilled water and pass it through an ion exchange resin. The effluent is an aqueous solution of 3-mercaptopropanesulfonic acid. Wash the column with 6L of distilled water until the eluent is neutral to obtain an aqueous solution of 3-mercaptopropanesulfonic acid.

[0015] S44. Add 564g of 30% hydrogen peroxide to an aqueous solution of 3-mercaptopropanesulfonic acid, maintain at 13-15℃ for 8-10 hours, neutralize with 400g of NaOH aqueous solution, and evaporate the neutralized solution to dryness using a rotary evaporator to obtain high-purity sodium polydisulfide dipropanesulfonate.

[0016] By employing the above-mentioned technical solutions, high-purity sodium didisulfide dipropane sulfonate can be prepared, which can control the nucleation and growth of copper layers in copper electrodeposition, refine grains, and thus improve the gloss of the copper plating layer. Sodium didisulfide dipropane sulfonate, in synergy with hydroxyethyl cellulose and collagen, can improve the tensile strength and elongation of the electroplated copper layer. Sodium didisulfide dipropane sulfonate, in synergy with other wetting agents, can refine and homogenize the copper plating grains, obtaining uniform, dense, and fine grains, thereby improving the through-hole filling efficiency and plating uniformity. Sodium didisulfide dipropane sulfonate can also achieve super-filling without voids or gaps in blind vias with higher aspect ratios, exhibiting excellent deep plating capability and meeting the conductivity requirements of through-hole plating in circuit boards.

[0017] Preferably, the leveling agent is pyridine benzyl ammonium chloride.

[0018] Preferably, the preparation method of the pyridine benzyl ammonium chloride is as follows: pyridine is added to a reactor, heated to 50-60°C, stirred at 300 rpm for 1-2 hours, and benzyl chloride is added dropwise using a constant pressure dropping funnel. The mixture is heated to 50-60°C and refluxed for 3-4 hours. The product is transferred to a round beaker and cooled to obtain a slightly light brown viscous liquid. The liquid is recrystallized with petroleum ether and filtered to obtain pyridine benzyl ammonium chloride.

[0019] The prepared pyridine benzylammonium chloride, using the above-mentioned technical solution, possesses high purity and excellent leveling properties, making it suitable as a leveling agent in copper electroplating. By promoting the uniform distribution of copper ions on the cathode surface, pyridine benzylammonium chloride helps improve the filling efficiency of the electroplating process. It also refines and unifies the grain size of the electroplated copper layer, resulting in uniform, dense, and fine grains, which enhances the overall uniformity of the plating layer. During electroplating, pyridine benzylammonium chloride helps copper ions deposit deeper into the vias, thereby improving deep plating capability and ensuring good conductivity even in complex circuit board via plating. The nitrogen-containing aromatic heterocycles in pyridine benzylammonium chloride readily undergo electrophilic reactions, making the compound more easily adsorbed onto the cathode surface, thus providing a more stable plating environment. Pyridine benzylammonium chloride works synergistically with other components (such as wetting agents and brighteners) to jointly improve the performance of the electroplated copper layer. For example, when used in synergy with brighteners, it can further refine grains and enhance gloss; when used in synergy with wetting agents, it can improve the smoothness and density of the coating.

[0020] Preferably, the ratio of pyridine, benzyl chloride and petroleum ether is 1 mol: 1 mol: 550-600 mL.

[0021] Preferably, the wetting agent is at least one selected from sodium dodecyl sulfate, fatty amine polyoxyethylene ether, and polyethylene oxide polyoxypropylene monobutyl ether.

[0022] Preferably, the wetting agent is composed of sodium dodecyl sulfate, fatty amine polyoxyethylene ether, and polyethylene oxide polyoxypropylene monobutyl ether in a mass ratio of 5:8:2.

[0023] By adopting the above technical solution, the wetting agent in the acidic copper plating brightener is composed of sodium dodecyl sulfate, fatty amine polyoxyethylene ether, and polyethylene oxide polyoxypropylene monobutyl ether in a mass ratio of 5:8:2. These three wetting agents each have their unique functions and play a synergistic role in the electroplating process. Sodium dodecyl sulfate: This is an anionic surfactant that can reduce the surface tension of the electroplating solution and improve the wettability of the solution to the substrate. It helps the electroplating solution spread better on the surface of the object being plated, ensuring uniform deposition of copper ions on the substrate, thereby obtaining a smooth and uniform coating. Fatty amine polyoxyethylene ether: This nonionic surfactant has excellent wetting and penetrating capabilities, which can improve copper deposition in high current density areas. It stabilizes copper ions in the electroplating solution, reducing localized excessively rapid deposition of copper ions and avoiding the formation of a rough coating. Polyoxyethylene polyoxypropylene monobutyl ether: As a copolymer-type nonionic surfactant, it helps improve the uniformity and gloss of the coating. This wetting agent can form a uniform adsorption film on the electrode surface, which helps control the copper crystallization process, resulting in finer grains and a smoother, more delicate coating. The synergistic effect of these three wetting agents is manifested in: mutually reducing surface tension, improving the solution's coverage of the substrate, and ensuring uniform distribution of copper ions across the entire workpiece surface; stabilizing the electroplating solution, preventing copper ions from depositing too quickly in specific areas, thus avoiding uneven coating and scorching; and controlling the crystallization process, promoting the formation of fine and uniform grains, and improving the gloss and smoothness of the coating.

[0024] In summary, by using the appropriate ratio and interaction of these wetting agents, the performance of acidic copper plating brighteners can be significantly improved, resulting in high-quality copper plating layers that meet the requirements of precision circuit board manufacturing.

[0025] Secondly, this application provides a method for preparing an acidic copper plating brightener, using the following technical solution:

[0026] As a general technical concept, this application also provides a method for preparing the above-mentioned acidic copper plating brightener, comprising the following steps: according to the mass proportions, brightener, leveling agent, wetting agent, hydroxyethyl cellulose and collagen are added to deionized water in sequence and mixed thoroughly. The mixture is heated to a temperature of 80-90℃ and stirred at a stirring rate of 150-180r / min for 1-2h to obtain the acidic copper plating brightener.

[0027] In summary, the beneficial technical effects of this application are as follows:

[0028] 1. Excellent gloss, tensile strength, and elongation: The synergistic effect of hydroxyethyl cellulose and collagen helps to improve the gloss, tensile strength, and elongation of electroplated copper layers. Brighteners control the nucleation and growth of copper layers during copper electrodeposition, refine grains, further enhance gloss, and make the plating surface smoother and denser.

[0029] 2. Highly efficient through-hole filling and plating uniformity: By combining multiple synergistic wetting agents, the copper plating grains are refined and more uniform, resulting in uniform, dense, and fine grains. The use of pyridine benzyl ammonium chloride as a leveling agent in the copper electroplating process improves through-hole filling efficiency and plating uniformity.

[0030] 3. Excellent through-hole plating capability: The acidic copper plating brightener of this application can achieve super filling without voids and gaps in blind holes with higher aspect ratios, meeting the requirements of the through-hole conductivity of circuit boards.

[0031] 4. Improve the overall quality of electroplated copper layers: By optimizing the raw material ratio and preparation process, the acidic copper plating brightener of this application can effectively improve the overall quality of electroplated copper layers, including gloss, tensile strength, elongation, hole filling efficiency, uniform plating ability, and through-hole deep plating ability. Detailed Implementation

[0032] The embodiments of this application will be described in detail below with reference to examples. However, those skilled in the art will understand that the following examples are for illustrative purposes only and should not be considered as limiting the scope of this application. Unless otherwise specified in the examples, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all commercially available conventional products.

[0033] Preparation Example 1: Preparation of Sodium Polydithiodipropanesulfonate

[0034] The preparation method of sodium polydisulfide dipropane sulfonate includes the following steps:

[0035] S41. Add 6L of methanol and 1824g of thiourea to an enamel kettle and stir until homogeneous. Cool to 20°C and slowly add 2440g of 1,3-propanesulfonyl lactone, controlling the adding temperature at 28°C. After the addition is complete, continue the reaction at 32°C for 4.5 hours. Centrifuge and dry to obtain 3-isothiourea propanesulfonic acid.

[0036] S42. Add 1980g of 3-isothiourea propanesulfonic acid to an enamel-lined kettle and add it to 8.3L of 26% ammonia solution. Heat to 60°C with stirring until the salt dissolves. Cool to 14°C and maintain for 1 hour. Evaporate in a rotary evaporator until the solid precipitates. Cool to 14°C and recrystallize with a chloroform and isopropanol mixed solvent with a mass ratio of 1:1.3 to obtain ammonium 3-mercaptopropanesulfonate.

[0037] S43. Dissolve 1590g of ammonium 3-mercaptopropanesulfonate in 4L of distilled water, pass it through an ion exchange resin, and the effluent is an aqueous solution of 3-mercaptopropanesulfonate. Wash the column with 6L of distilled water until the effluent is neutral to obtain an aqueous solution of 3-mercaptopropanesulfonate.

[0038] S44. Add 564g of 30% hydrogen peroxide to an aqueous solution of 3-mercaptopropanesulfonic acid, keep at 14℃ for 9 hours, neutralize with 400g of NaOH aqueous solution, and evaporate the neutralized solution to dryness using a rotary evaporator to obtain high-purity sodium polydisulfide dipropanesulfonate.

[0039] Preparation Example 2: Preparation of pyridine benzyl ammonium chloride

[0040] The preparation method of the pyridine benzyl ammonium chloride is as follows: 1 mol of pyridine is added to a reactor, heated to 550°C, stirred at 300 rpm for 1.5 h, and 1 mol of benzyl chloride is added dropwise using a constant pressure dropping funnel. The mixture is heated to 55°C and refluxed for 3.6 h. The product is transferred to a round beaker and cooled to obtain a slightly light brown viscous liquid. The liquid is recrystallized with 580 mL of petroleum ether and filtered to obtain pyridine benzyl ammonium chloride.

[0041] Example 1

[0042] An acidic copper plating brightener, by mass parts, comprises the following raw materials: 25g brightener, 6g pyridine benzyl ammonium chloride, 40g wetting agent, 7g hydroxyethyl cellulose, 8g collagen, and 900g deionized water. The brightener is composed of sodium polydithiopropane sulfonate, sodium thiazolinyl dithiopropane sulfonate, and methylene blue in a mass ratio of 5:3:2. The wetting agent is sodium dodecyl sulfate.

[0043] The preparation method of the above-mentioned acidic copper plating brightener includes the following steps:

[0044] According to the mass fractions, brightener, pyridine benzyl ammonium chloride, wetting agent, hydroxyethyl cellulose and collagen are added to deionized water in sequence and mixed thoroughly. The mixture is heated to 80°C and stirred at a stirring rate of 150 r / min for 2 hours to obtain acidic copper plating brightener.

[0045] Example 2

[0046] An acidic copper plating brightener, by mass parts, comprises the following raw materials: 30g brightener, 8g pyridine benzyl ammonium chloride, 50g wetting agent, 10g hydroxyethyl cellulose, 12g collagen, and 930g deionized water. The brightener is composed of sodium polydithiopropane sulfonate, sodium thiazolinyl dithiopropane sulfonate, and methylene blue in a mass ratio of 5:3:2. The wetting agent is a fatty amine polyoxyethylene ether.

[0047] The preparation method of the above-mentioned acidic copper plating brightener includes the following steps:

[0048] According to the mass fractions, brightener, pyridine benzyl ammonium chloride, wetting agent, hydroxyethyl cellulose and collagen are added to deionized water in sequence and mixed thoroughly. The mixture is heated to 90°C and stirred at a stirring rate of 180 r / min for 1 hour to obtain acidic copper plating brightener.

[0049] Example 3

[0050] An acidic copper plating brightener, by mass parts, comprises the following raw materials: 28g brightener, 7g pyridine benzyl ammonium chloride, 45g wetting agent, 9.5g hydroxyethyl cellulose, 11g collagen, and 920g deionized water. The brightener is composed of sodium polydithiopropane sulfonate, sodium thiazolinyl dithiopropane sulfonate, and methylene blue in a mass ratio of 5:3:2. The wetting agent is polyethylene oxide polypropylene oxide monobutyl ether.

[0051] The preparation method of the above-mentioned acidic copper plating brightener includes the following steps:

[0052] According to the mass proportions, the brightener, pyridine benzyl ammonium chloride, wetting agent, hydroxyethyl cellulose and collagen are added to deionized water in sequence and mixed thoroughly. The mixture is heated to 85°C and stirred at a stirring rate of 160 r / min for 1.5 h to obtain the acidic copper plating brightener.

[0053] Example 4

[0054] An acidic copper plating brightener, by mass parts, comprises the following raw materials: 28g brightener, 7g pyridine benzyl ammonium chloride, 45g wetting agent, 9.5g hydroxyethyl cellulose, 9.5g collagen, and 920g deionized water. The brightener is composed of sodium polydithiopropane sulfonate, sodium thiazolinyl dithiopropane sulfonate, and methylene blue in a mass ratio of 5:3:2. The wetting agent is composed of sodium dodecyl sulfate, fatty amine polyoxyethylene ether, and polyoxyethylene polyoxypropylene monobutyl ether in a mass ratio of 5:8:2.

[0055] The preparation method of the above-mentioned acidic copper plating brightener includes the following steps:

[0056] According to the mass proportions, the brightener, pyridine benzyl ammonium chloride, wetting agent, hydroxyethyl cellulose and collagen are added to deionized water in sequence and mixed thoroughly. The mixture is heated to 85°C and stirred at a stirring rate of 160 r / min for 1.5 h to obtain the acidic copper plating brightener.

[0057] Comparative Example 1

[0058] Same as in Example 4, except that the brightener is sodium polydithiopropane sulfonate.

[0059] Comparative Example 2

[0060] Same as Example 4, except that the brightener is sodium thiazolinyl dithiopropane sulfonate.

[0061] Comparative Example 3

[0062] Same as in Example 4, except that the brightener is methylene blue.

[0063] Comparative Example 4

[0064] Similar to Example 4, except that an equal amount of sodium polydisulfide dipropane sulfonate produced by Wuhan Hechang Chemical Co., Ltd. was used instead of the sodium polydisulfide dipropane sulfonate prepared in Example 1 of this application.

[0065] Performance testing

[0066] Samples of the acidic copper plating brighteners prepared in Examples 1-4 and Comparative Examples 1-4 were taken and added to the copper plating solution. The copper plating solution formula was: Cu2 + (60±5)g / L, sulfuric acid (120±10)g / L, Cl - (50±10) mg / L, acidic copper plating brightener 3 mL / L, current density 30 A / dm³ 2 The temperature was (26±2)℃.

[0067] Sample 1: Copper foil was cut into 200mm × 15mm samples using a special fixture, and after degreasing and activation treatment, it was electroplated in the above-mentioned copper plating solution. The tensile strength, gloss, and elongation of the copper foil were tested, and the test results are shown in Table 1.

[0068] Gloss: The gloss of the rough surface of the copper foil was measured using a WG-60G universal portable precision gloss meter from Shenzhen Weifu Optoelectronics Technology Co., Ltd. The projection angle was 60°. Three points were measured on the left, center and right sides of the horizontal strip of the rough copper foil, and the average value was taken.

[0069] Tensile strength and elongation: Tensile strength and elongation were tested using an LD-1000A Class 1 electronic tensile testing machine manufactured by Jinan Jiazheng Instrument Manufacturing Co., Ltd., at a tensile rate of 10 mm / min. The required tensile strength is ≥280 MPa, and the elongation is ≥2%.

[0070] Test of plating depth capability: Using the brass tube insertion method, insert a brass sheet into a 10mm×100mm diameter brass tube, seal one end, and place the open end of the brass tube perpendicular to the anode, 20mm away from the anode. After plating, remove the tube and measure the length of the plating layer on the brass sheet. The depth capability of the plating layer inside the brass tube can be obtained. The longer the length, the better the depth capability. The test results are shown in Table 1 below.

[0071] Testing of plating uniformity: The HullCell test method was used. The nickel-plated sample was placed in the HullCell and electroplated with a current of 1A for 60 minutes. Then, the plating thickness at the center of the square was measured as required. The plated HullCell sample was divided into 4 areas, and the thickness at the center of squares 1-4 was measured. The uniformity was calculated using the following formula: T = A × 100% / B, where A is the plating thickness of any square selected from squares 2-4; B is the plating thickness in square 1. The test results are shown in Table 2 below.

[0072] Table 1 Performance Tests

[0073] project Gloss (60°) Tensile strength / MPa Elongation / % Deep plating capability / mm Example 1 249 383 2.8 44 Example 2 255 382 2.8 45 Example 3 258 393 2.9 47 Example 4 276 412 3.2 49 Comparative Example 1 213 357 2.5 41 Comparative Example 2 208 361 2.4 42 Comparative Example 3 223 358 2.6 40 Comparative Example 4 232 372 2.7 44

[0074] Table 2. Plating Ability Test

[0075]

[0076] Analyzing the data in Tables 1 and 2, we can see that:

[0077] 1) The electroplated copper layer obtained by the acidic copper plating brightener prepared in Examples 1-4 has excellent gloss, tensile strength and elongation, as well as excellent uniform plating ability and deep plating ability, which meets the requirements of the through-hole conductivity of the circuit board.

[0078] 2) A comparative analysis of the performance of the acidic copper plating brighteners prepared in Examples 4 and 1-3 shows that the wetting agent, composed of sodium dodecyl sulfate, fatty amine polyoxyethylene ether, and polyethylene oxide polypropylene oxide monobutyl ether in a mass ratio of 5:8:2, works synergistically to reduce surface tension, improve the solution's coverage of the substrate, and ensure uniform distribution of copper ions across the entire workpiece surface. This stabilizes the plating solution, preventing excessively rapid deposition of copper ions in specific areas, thus avoiding uneven plating and scorching. It also controls the crystallization process, promoting the formation of fine and uniform grains, and improving the gloss and smoothness of the plating layer.

[0079] 3) A comparative analysis of the performance of the acidic copper plating brighteners prepared in Example 4 and Comparative Examples 1-3 shows that the brightener, composed of sodium polydithiopropane sulfonate, sodium thiazolinyl dithiopropane sulfonate, and methylene blue in a mass ratio of 5:3:2, utilizes their synergistic effect to control the nucleation and growth of the copper layer during copper electrodeposition. In the instantaneous nucleation process controlled by three-dimensional diffusion, the grains are refined, gloss is improved, and the plating surface becomes smoother and denser. This allows for effective control of the copper electrodeposition process, resulting in electroplated copper layers with excellent gloss, tensile strength, and elongation.

[0080] 4) A comparative analysis of the performance of the acidic copper plating brighteners prepared in Example 4 and Comparative Example 4 shows that the high-purity sodium didithiopropane sulfonate prepared in this application can control the nucleation and growth of the copper layer in copper electrodeposition, refine the grains, and thus improve the gloss of the copper plating layer. Sodium didithiopropane sulfonate, in synergy with hydroxyethyl cellulose and collagen, can improve the tensile strength and elongation of the electroplated copper layer. Sodium didithiopropane sulfonate, in synergy with other wetting agents, can refine the copper plating grains more uniformly, obtaining uniform, dense, and fine grains, thereby improving the through-hole filling efficiency, uniform plating ability, and deep plating ability, meeting the requirements for the conductivity of through-holes in circuit boards.

[0081] The above embodiments are only used to explain the technical solutions of this application and are not intended to limit it. Although the above embodiments have provided specific descriptions of this application, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the specific implementation of this invention. Any modifications and equivalent substitutions that do not depart from the spirit and scope of this application should be covered within the protection scope of this application.

Claims

1. An acidic copper plating brightener, characterized in that, The preparation materials include the following raw materials by weight: 25-30 parts of brightener, 6-8 parts of leveling agent, 40-50 parts of wetting agent, 7-10 parts of hydroxyethyl cellulose, 8-12 parts of collagen, and 900-930 parts of deionized water. The mass ratio of the hydroxyethyl cellulose to the collagen is 1:1; The brightener is composed of sodium polydithiopropane sulfonate, sodium thiazolinyl dithiopropane sulfonate and methylene blue in a mass ratio of 5:3:

2. The preparation method of the sodium polydisulfide dipropane sulfonate includes the following steps: S41. Add 6L of methanol and 1824g of thiourea to an enamel kettle and stir until homogeneous. Cool the temperature to 20℃ and slowly add 2440g of 1,3-propanesulfonyl lactone, controlling the adding temperature at 25-30℃. After the addition is complete, continue the reaction at 32℃ for 4-5 hours. Centrifuge and dry to obtain 3-isothiourea propanesulfonic acid. S42. Add 1980g of 3-isothiourea propanesulfonic acid to an enamel-lined kettle and add it to 8.3L of 26% ammonia solution. Heat to 60°C with stirring until the salt dissolves. Cool to 13-15°C and maintain for 1 hour. Evaporate in a rotary evaporator until the solid precipitates. Cool to 13-15°C and recrystallize with a chloroform and isopropanol mixed solvent with a mass ratio of 1:1.3 to obtain ammonium 3-mercaptopropanesulfonate. S43. Dissolve 1590g of ammonium 3-mercaptopropanesulfonate in 4L of distilled water, pass it through an ion exchange resin, and the effluent is an aqueous solution of 3-mercaptopropanesulfonate. Wash the column with 6L of distilled water until the effluent is neutral to obtain an aqueous solution of 3-mercaptopropanesulfonate. S44. Add 564g of 30% hydrogen peroxide to the aqueous solution of 3-mercaptopropanesulfonic acid, keep it at 13-15℃ for 8-10 hours, neutralize it with 400g of NaOH aqueous solution, and evaporate the neutralized solution to dryness using a rotary evaporator to obtain high-purity sodium polydisulfide dipropanesulfonate. The leveling agent is pyridine benzyl ammonium chloride; The wetting agent is composed of sodium dodecyl sulfate, fatty amine polyoxyethylene ether, and polyethylene oxide polyoxypropylene monobutyl ether in a mass ratio of 5:8:

2.

2. The acidic copper plating brightener according to claim 1, characterized in that, The preparation method of the pyridine benzyl ammonium chloride is as follows: pyridine is added to a reactor, heated to 50-60℃, stirred at 300 rpm for 1-2 h, and benzyl chloride is added dropwise using a constant pressure dropping funnel. The mixture is heated to 50-60℃ and refluxed for 3-4 h. The product is transferred to a round beaker and cooled to obtain a slightly light brown viscous liquid. The liquid is recrystallized with petroleum ether and filtered to obtain pyridine benzyl ammonium chloride.

3. The acidic copper plating brightener according to claim 2, characterized in that, The ratio of pyridine, benzyl chloride, and petroleum ether used is 1 mol: 1 mol: 550-600 mL.

4. A method for preparing an acidic copper plating brightener according to any one of claims 1-3, characterized in that, Includes the following steps: According to the mass proportions, add the brightener, leveling agent, wetting agent, hydroxyethyl cellulose and collagen to deionized water in sequence and mix thoroughly. Heat to 80-90℃ and stir at a stirring rate of 150-180r / min for 1-2 hours to obtain the acidic copper plating brightener.

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