An environment-friendly copper deposition agent, its preparation method and application

Abstract

The present invention relates to the field of electroless copper plating materials, and provides an environment-friendly electroless copper plating agent and a preparation method thereof. The electroless copper plating agent comprises a quaternized chitosan complexing agent, a chitosan-cysteine derivative, a chitosan-glutathione derivative, tea polyphenols, dopamine, potassium citrate trihydrate, ascorbic acid, glucose, sodium alginate, sodium citrate and an ethanol-water mixed solvent. The preparation method includes the synthesis of chitosan derivatives, the preparation of complexing agents and the preparation of electroless copper plating agents. By optimizing the stability of complexing agents, the copper ion complexing ability and the deposition uniformity, the adhesion and uniformity of the deposited layer are improved. The obtained electroless copper plating agent solution has a stable conductivity and a controllable copper deposition rate, and is suitable for electronic circuit manufacturing and metal surface treatment. The present invention uses natural polymer complexing agents to replace traditional harmful complexing agents, realizes high-efficiency and environment-friendly electroless copper plating, reduces environmental pollution, and has good industrial application value.

Description

Technical Field

[0001] The present invention relates to the field of electroless copper plating materials, and particularly to an environment-friendly electroless copper plating agent, a preparation method thereof, and an application thereof. Background Art

[0002] In industrial fields such as electronic circuit manufacturing, printed circuit board (PCB) processing, and metal surface treatment, the electroless copper plating process is widely used in the formation of conductive layers to ensure the reliability and conductivity of circuits. With the development of electronic products towards high density, light weight, and high performance, the uniformity, adhesion, and conductivity of the electroless copper plating layer have become key performance indicators. At the same time, the environmental friendliness of the process has also attracted increasing attention. In practical applications, the electroless copper plating agent needs to have good complexing ability to stabilize copper ions and control the deposition rate, ensuring a uniform and defect-free coating. In addition, to meet the processing requirements of different substrates and complex structures, the electroless copper plating agent also needs to have good stability to prevent abnormal precipitation or defects in the deposition layer during the deposition process. With the increasingly strict environmental protection regulations, electroless copper plating agents containing EDTA, ammonia complexes, or formaldehyde systems commonly used in traditional electroless copper plating processes are restricted due to environmental pollution problems. Therefore, the development of an environment-friendly electroless copper plating agent that takes into account both deposition performance and environmental friendliness not only helps to improve the green level of electronic manufacturing processes but also promotes the sustainable development of this field and meets the urgent needs of the industry for high-performance and low-pollution electroless copper plating processes.

[0003] However, most of the common electroless copper plating agents on the market at present rely on traditional complexing agents such as EDTA and its derivatives. Although these chemical substances can provide good copper ion complexing ability, their biodegradability is poor, and they are prone to cause heavy metal pollution during the waste liquid treatment process, increasing the environmental governance cost. For example, the Chinese patent with the publication number CN101698936B discloses a chemical copper plating solution of sodium hypophosphite-ethylenediaminetetraacetic acid disodium system, which can improve the deposition rate and coating quality, but the complexing agent used has a high environmental risk, and the waste liquid discharge needs to be strictly controlled. In addition, some electroless copper plating processes use formaldehyde as a reducing agent. However, formaldehyde has strong toxicity and volatility, and there are health and safety hazards in long-term use. At the same time, although some environment-friendly electroless copper plating agents use complexing agents such as citric acid or amino acids to replace EDTA, due to their relatively weak complexing ability, the copper ion complexing is unstable, and problems such as uneven deposition rate and insufficient coating adhesion are prone to occur during the deposition process. Therefore, the existing technology has not yet achieved a good balance between environmental friendliness and deposition performance, and further optimization of the selection of complexing agents and formulation design is still needed to ensure the quality and stability of the deposition layer while improving the environmental friendliness of the electroless copper plating process. Summary of the Invention

[0004] (1) Technical Problems to be Solved

[0005] The object of the present invention is to provide an environment-friendly copper deposition agent, its preparation method and application, so as to solve the problems of insufficient environmental protection and deposition performance of the current copper deposition agent.

[0006] (2) Technical solution

[0007] In order to achieve the above object, the present invention provides the following technical solution:

[0008] An environment-friendly copper deposition agent, comprising the following raw materials in parts by weight: 8-15 parts of quaternized chitosan complexing agent, 5-10 parts of chitosan-cysteine derivative, 2.5-6.0 parts of chitosan-glutathione derivative, 2.0-6.0 parts of tea polyphenols, 2.5-6.0 parts of dopamine, 10-20 parts of potassium citrate trihydrate, 2-6 parts of ascorbic acid, 2-5 parts of glucose, 0.5-2 parts of sodium alginate, 0.5-2.0 parts of sodium citrate, and 50-80 parts of ethanol-water mixed solvent.

[0009] Further, the quaternized chitosan complexing agent is prepared by swelling chitosan with a deacetylation degree of 80-95% and a molecular weight of 100-300 kDa in an acetic acid-ethanol mixed solvent, reacting with 2,3-epoxypropyltrimethylammonium chloride under heating and reflux conditions, and then performing precipitation, washing and vacuum drying;

[0010] The chitosan-cysteine derivative is prepared by swelling chitosan with a deacetylation degree of 80-95% and a molecular weight of 50-200 kDa in an acidic aqueous solution, reacting with pre-activated L-cysteine under stirring conditions, and then performing freeze-drying;

[0011] The chitosan-glutathione derivative is prepared by swelling chitosan with a deacetylation degree of 80-95% and a molecular weight of 50-200 kDa in an acidic aqueous solution, reacting with glutathione and a cross-linking agent under stirring at an appropriate pH condition, and then performing freeze-drying.

[0012] Further, the preparation method of the quaternized chitosan complexing agent is as follows: in parts by weight, 30-60 parts of 1 wt.% acetic acid aqueous solution and 30-60 parts of ethanol are mixed to form a solvent system, 1.5-2.0 parts of chitosan is added and stirred for swelling for 120-180 min, then 3.5-4.5 parts of 2,3-epoxypropyltrimethylammonium chloride is added, and the reaction is refluxed at 75-85 °C for 10-14 h. After the reaction is completed, the system is cooled to 25-30 °C, 500-800 parts of acetone is added to precipitate the product, and the precipitate is collected and then centrifugally washed 3-5 times with a mixed solvent of anhydrous ether and acetone, where the volume ratio of anhydrous ether to acetone is 1:(10-13), and finally vacuum dried at -0.08-0.10 MPa and 40-60 °C for 12-24 h to obtain the quaternized chitosan complexing agent.

[0013] The design of the quaternized chitosan complexing agent in this invention is mainly used to enhance the complexing stability and deposition uniformity of the copper deposition agent. Through the acetic acid - ethanol mixed solvent system, chitosan is fully swollen to ensure the three - dimensional stretching of the molecular chain, providing uniformly exposed active sites for subsequent quaternization reactions. Under precisely controlled heating and reflux conditions, the epoxy group of 2,3 - epoxypropyltrimethylammonium chloride undergoes a highly efficient ring - opening reaction with the amino group of chitosan to form a stable quaternized structure. By regulating the solvent polarity, the reaction activity is optimized, realizing the hydrophilicity regulation and uniform charge distribution of the chitosan backbone, enabling it to exhibit significant electrostatic adsorption ability and complexing stability in solution. Acetone precipitation is used to preliminarily remove unreacted substances, and combined with anhydrous ether - acetone composite washing to further improve the product purity. At the same time, the vacuum drying conditions are precisely controlled to avoid structural collapse caused by violent desolvation, ensuring the uniform distribution and complexing activity of the quaternary ammonium groups. The synergistic effects of each component include: the acetic acid - ethanol system promotes chitosan swelling through the hydrogen - bonding effect of acetic acid, while ethanol regulates the solvent polarity to optimize the molecular structure; the steric hindrance effect and charge characteristics of 2,3 - epoxypropyltrimethylammonium chloride synergistically enhance the copper ion complexing ability; the gradient washing with polar solvents improves the chemical purity, and the mild drying conditions ensure the complexing stability and deposition control ability of the product, ultimately forming a spatial topological structure with multi - level complexing ability to precisely regulate the migration rate and deposition behavior of copper ions.

[0014] Furthermore, the preparation method of the chitosan - cysteine derivative is as follows: by weight, 1.0 - 5.0 parts of chitosan are dispersed in 50 - 150 parts of 1.0 - 1.5 wt.% hydrochloric acid aqueous solution, and stirred and swollen for 30 - 60 min to form a homogeneous solution; separately, 0.5 - 3.0 parts of L - cysteine are dissolved in 50 - 100 parts of deionized water, and 0.1 - 0.5 parts of 1 - ethyl - (3 - dimethylaminopropyl) carbodiimide hydrochloride are added, and the activation time is controlled to be 15 - 30 min; the activated cysteine solution is slowly added dropwise to the chitosan solution, and the pH of the system is adjusted to 4.0 - 5.5 with 1 vol.% hydrochloric acid solution, and continuously stirred and reacted at 25 - 40 °C for 4 - 8 h. After the reaction, the solution is freeze - dried for 24 - 48 h to obtain the chitosan - cysteine derivative.

[0015] The design of the chitosan-cysteine derivative in the present invention is mainly used to enhance the complexing ability of the copper deposition agent and the adhesion performance of the coating. The chitosan molecules are controllably swollen in an aqueous hydrochloric acid solution system, so that the molecular chains are fully extended and the amino active sites are activated through protonation, providing a structural basis for subsequent chemical modification. 1-Ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride selectively activates the carboxyl group of L-cysteine to generate a highly reactive intermediate, which forms an amide bond with the chitosan amino group in a weakly acidic condition, realizing the precise grafting of the mercapto functional group. The synergistic optimization of the swelling degree, activation efficiency and reaction pH ensures the uniform distribution and spatial orientation of the mercapto groups on the chitosan backbone, forming a multi-level coordination network. The complexing stability is improved through the strong coordination of mercapto-copper ions and the chelation effect of the chitosan backbone, and at the same time, the bonding strength between the coating and the substrate is enhanced through interfacial chemical bonding.

[0016] Further, the preparation method of the chitosan-glutathione derivative is as follows: by weight, 0.2-0.5 parts are dispersed in 1.8-3.0 parts of 1.0-1.2 mol / L aqueous hydrochloric acid solution, 8-15 parts of deionized water are added to form a colloidal dispersion system with a polymer concentration of 0.8%-1.5 wt.%, the pH of the system is adjusted to 5.5-6.5 with 1 vol.% hydrochloric acid, and then 1.5-3.0 parts of an aqueous glutathione solution with a concentration of 200-300 mg / mL are added; 0.1-0.3 parts of 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride and 0.05-0.15 parts of N-hydroxysuccinimide are added in sequence, the pH value is maintained at 5.8-6.2, and magnetic stirring reaction is carried out at 15-30 °C for 12-24 h; the reaction solution is freeze-dried at -70--90 °C and 0.01-0.05 MPa for 36-72 h to obtain the chitosan-glutathione derivative.

[0017] The design of the chitosan-glutathione derivative in the present invention is mainly used to enhance the antioxidant stability and complexing ability of the copper deposition agent. Through the chemical modification of chitosan and glutathione, sulfhydryl and carboxyl functional groups are introduced, enabling it to effectively complex copper ions during the copper deposition process, while providing antioxidant protection and reducing the risk of premature reduction of copper ions, thereby improving the uniformity and stability of the deposited layer. Chitosan is dispersed in an aqueous hydrochloric acid solution at an appropriate concentration to form a colloidal system, ensuring the full expansion of its molecular chain and improving the subsequent binding efficiency with glutathione. Under appropriate pH regulation, the addition of the glutathione solution further endows chitosan with stronger complexing and antioxidant abilities, and the synergistic effect of 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride and N-hydroxysuccinimide promotes the stable chemical bonding between chitosan and glutathione, improving the structural stability and chemical activity of the derivative. A long reaction under suitable temperature and stirring conditions ensures the full combination of functional groups, and at the same time, a low-temperature freeze-drying process is adopted to avoid the destruction of the structures of chitosan and glutathione at high temperatures, thereby maintaining their excellent solubility and functional activity.

[0018] Further, the volume ratio of ethanol to water in the ethanol-water mixed solvent is 1:(2.0 - 4.5);

[0019] Further, the solution conductivity of the copper deposition agent is controlled at 5 - 15 mS / cm;

[0020] Further, the copper deposition rate of the copper deposition agent is 1.5 - 3.0 μm / min;

[0021] The present invention also provides a preparation method of an environmentally friendly copper deposition agent, comprising the following steps:

[0022] S1. According to the ratio, dissolve the quaternized chitosan complexing agent, chitosan-cysteine derivative and chitosan-glutathione derivative in an ethanol-water mixed solvent, and carry out the dissolution process at a stirring rate of 400 - 600 rpm for 30 - 60 min, controlling the system temperature at 25 - 35°C;

[0023] S2. Preparation of the prepolymer solution: sequentially add tea polyphenols, dopamine, potassium citrate trihydrate, ascorbic acid and glucose to the dissolved system, maintain the temperature at 25 - 35°C, and mix at a stirring speed of 300 - 500 rpm until completely dissolved, and control the total addition time at 10 - 20 min.

[0024] S3. Prepare the coating: slowly add sodium alginate and sodium citrate, adjust the pH of the system to 4.5-6.5, continue stirring at 400-600 rpm for 30-60 min to ensure that the system is uniform and stable. After the final solution is filtered through a 0.45 μm filter membrane, stand at 4-8°C in the dark for 12-24 h to complete the aging process.

[0025] The invention also discloses the application of an environmentally friendly copper deposition agent in the manufacture of electronic circuits, copper deposition of printed circuits, electromagnetic shielding coatings and flexible electronic devices.

[0026] The present invention adopts the design of environmentally friendly copper deposition agent mainly for enhancing the complexing stability, redox regulation ability and deposition uniformity of the deposition system. Through the synergistic effect of quaternized chitosan complexing agent, chitosan-cysteine ​​derivative and chitosan-glutathione derivative, efficient complexing and deposition control of copper ions are achieved. Among them, the quaternized chitosan complexing agent improves solubility and complexing stability, the chitosan-cysteine ​​derivative enhances the adhesion of the coating, and the chitosan-glutathione derivative prevents the premature reduction of copper ions to ensure uniform deposition. In the ethanol-water mixed solvent system, the temperature and stirring rate are controlled to ensure that the complexing agent is fully dissolved and evenly dispersed. Tea polyphenols and dopamine further enhance the antioxidant capacity and regulate the release rate of copper ions through complexing, potassium trihydrate citric acid and ascorbic acid construct a stable pH buffer system, and dynamically regulate the deposition behavior of copper, and glucose optimizes the deposition environment and improves the stability of the system. Sodium alginate and sodium citrate ensure the uniformity and rheological properties of the coating and optimize the complexing state of copper ions. The system is filtered through a filter membrane and aged at low temperature to ensure the long-term stability and deposition activity of the copper depositing agent. The present invention improves the complexing stability, redox regulation ability and deposition uniformity of the copper depositing agent through complexing agent optimization and multi-component synergy, ensuring its efficient application in the fields of electronic circuit manufacturing, printed circuit copper deposition, electromagnetic shielding coating and flexible electronic device manufacturing.

[0027] (3) Beneficial technical effects

[0028] 1. The present invention improves the stability and uniformity of the copper deposition agent by using a quaternized chitosan complexing agent. The components synergistically optimize the complexing ability, purity and deposition control, achieve precise migration of copper ions, improve process consistency, reduce defects, and meet the high standards of electronic manufacturing.

[0029] 2. The present invention improves the complexing ability of the copper precipitant and the adhesion performance of the coating through precise modification of chitosan-cysteine ​​derivatives. Swelling control, activation optimization and pH adjustment work together to ensure the uniform distribution of thiol groups, build a multi-level coordination network, enhance the copper ion complexing stability and coating bonding strength, and improve deposition uniformity and reliability.

[0030] 3. The present invention improves the antioxidant stability and complexing ability of the copper deposition agent through precise modification with chitosan - glutathione derivatives. The sulfhydryl group and carboxyl group cooperate to complex copper ions, prevent premature reduction of copper ions, and improve the uniformity of the deposited layer. pH regulation, chemical bonding, and freeze - drying optimize the stability of the derivatives to ensure efficient application.

[0031] 4. The present invention improves solubility and complexing stability through quaternized chitosan, enhances the adhesion of the plating layer with chitosan - cysteine derivatives, and prevents premature reduction of copper ions with chitosan - glutathione derivatives. Tea polyphenols and dopamine enhance the antioxidant capacity, potassium citrate trihydrate and ascorbic acid construct a pH buffer system to regulate deposition, glucose optimizes the deposition environment, and sodium alginate and sodium citrate ensure the uniformity of the coating, improving the stability of the copper deposition system and being applicable to the field of electronic manufacturing. Brief Description of the Drawings

[0032] Figure 1 It is the infrared Fourier spectrum of the chitosan - cysteine derivative prepared in Example 1 of the present invention.

[0033] Figure 2 It is the morphology of through - hole electroplated copper prepared with the copper deposition agent based on Example 1 of the present invention. Detailed Description of the Embodiments

[0034] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention.

[0035] Example 1

[0036] An environment - friendly copper deposition agent comprises the following raw materials in parts by weight: 8 parts of quaternized chitosan complexing agent, 5 parts of chitosan - cysteine derivative, 2.5 parts of chitosan - glutathione derivative, 2.0 parts of tea polyphenols, 2.5 parts of dopamine, 10 parts of potassium citrate trihydrate, 2 parts of ascorbic acid, 2 parts of glucose, 0.5 part of sodium alginate, 0.5 part of sodium citrate, and 50 parts of ethanol - water mixed solvent.

[0037] The quaternized chitosan complexing agent is prepared by swelling chitosan with a deacetylation degree of 80% and a molecular weight of 100 kDa in an acetic acid - ethanol mixed solvent, reacting with 2,3 - epoxypropyl trimethyl ammonium chloride under heating and reflux conditions, and then subjecting to precipitation, washing, and vacuum drying; the chitosan - cysteine derivative is prepared by swelling chitosan with a deacetylation degree of 80% and a molecular weight of 50 kDa in an acidic aqueous solution, reacting with pre - activated L - cysteine under stirring conditions, and then subjecting to freeze - drying; the chitosan - glutathione derivative is prepared by swelling chitosan with a deacetylation degree of 80% and a molecular weight of 50 kDa in an acidic aqueous solution, reacting with glutathione and a cross - linker under stirring at an appropriate pH condition, and then subjecting to freeze - drying.

[0038] The preparation method of the quaternized chitosan complexing agent is as follows: by weight, 30 parts of 1 wt.% acetic acid aqueous solution and 30 parts of ethanol are mixed to form a solvent system, 1.5 parts of chitosan is added and stirred to swell for 120 min, then 3.5 parts of 2,3-epoxypropyltrimethylammonium chloride is added, and the reaction is refluxed at 75 °C for 10 h. After the reaction, the system is cooled to 25 °C, 500 parts of acetone is added to precipitate the product, and the precipitate is collected and centrifugally washed 3 times with a mixed solvent of anhydrous ether and acetone, where the volume ratio of anhydrous ether to acetone is 1:10. Finally, it is vacuum dried at -0.08 MPa and 40 °C for 12 h to obtain the quaternized chitosan complexing agent.

[0039] The preparation method of the chitosan-cysteine derivative is as follows: by weight, 1.0 part of chitosan is dispersed in 50 parts of 1.0 wt.% hydrochloric acid aqueous solution and stirred to swell for 30 min to form a homogeneous solution; another 0.5 part of L-cysteine is dissolved in 50 parts of deionized water, and 0.1 part of 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride is added, and the activation time is controlled to be 15 min; the activated cysteine solution is slowly added dropwise to the chitosan solution, and the pH of the system is adjusted to 4.0 with 1 vol.% hydrochloric acid solution, and the reaction is continuously stirred at 25 °C for 4 h. After the reaction, the solution is freeze-dried for 24 h to obtain the chitosan-cysteine derivative.

[0040] The preparation method of the chitosan-glutathione derivative is as follows: by weight, 0.2 part is dispersed in 1.8 parts of 1.0 mol / L hydrochloric acid aqueous solution, 8 parts of deionized water is added to form a colloidal dispersion system with a polymer concentration of 0.8 wt.%, and the pH of the system is adjusted to 5.5 with 1 vol.% hydrochloric acid and then 1.5 parts of a 200 mg / mL glutathione aqueous solution is added; 0.1 part of 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride and 0.05 part of N-hydroxysuccinimide are added in sequence, and the pH value is maintained at 5.8, and the reaction is magnetically stirred at 15 °C for 12 h; the reaction solution is freeze-dried at -70 °C and 0.01 MPa for 36 h to obtain the chitosan-glutathione derivative.

[0041] The volume ratio of ethanol to water in the ethanol-water mixed solvent is 1:2.0; the solution conductivity of the copper precipitation agent is controlled at 5 mS / cm; the copper deposition rate of the copper precipitation agent is 1.5 μm / min.

[0042] The preparation method of an environment-friendly copper precipitation agent in this embodiment includes the following steps:

[0043] S1. According to the ratio, dissolve the quaternized chitosan complexing agent, chitosan-cysteine derivative and chitosan-glutathione derivative in an ethanol-water mixed solvent. The dissolution process is carried out at a stirring rate of 400 rpm for 30 min, and the system temperature is controlled at 25°C.

[0044] S2. Preparation of the prepolymer solution: Sequentially add tea polyphenols, dopamine, potassium citrate trihydrate, ascorbic acid and glucose to the dissolved system, maintain the temperature at 25°C, and mix at a stirring speed of 300 rpm until completely dissolved. The total addition time is controlled within 10 min.

[0045] S3. Preparation of the coating: Slowly add sodium alginate and sodium citrate, adjust the pH of the system to 4.5, continue to stir at a rate of 400 rpm for 30 min to ensure the uniformity and stability of the system. After the final solution is filtered through a 0.45 μm filter membrane, it is left to stand in the dark at 4°C for 12 h to complete the curing process.

[0046] It can be seen from Figure 1 that the chitosan-cysteine derivative (Cys-CS) prepared in the present invention has a new amide group absorption peak at 1637 cm⁻¹ and an S-H stretching vibration peak at 2550 cm⁻¹ in the infrared spectrum compared with chitosan, indicating that cysteine has been successfully grafted onto the chitosan molecular chain to form a stable chemical bond. This structure endows the material with stronger complexing ability and chemical stability, which is helpful for the efficient binding and controlled release of copper ions. Figure 2 It further verifies the excellent performance of the electroless copper plating agent of the present invention in through-hole electroplating copper. The deposited copper layer is uniform and has strong adhesion, proving that the optimized design of the complexing agent effectively improves the deposition quality and reliability, thus ensuring the application value of the electroless copper plating agent in the fields of electronic circuit manufacturing, etc.

[0047] Example 2

[0048] An environment-friendly electroless copper plating agent, comprising the following raw materials in parts by weight: 10 parts of quaternized chitosan complexing agent, 7 parts of chitosan-cysteine derivative, 3.5 parts of chitosan-glutathione derivative, 3.2 parts of tea polyphenols, 3.5 parts of dopamine, 13 parts of potassium citrate trihydrate, 3 parts of ascorbic acid, 3 parts of glucose, 1.0 part of sodium alginate, 1.0 part of sodium citrate, and 59 parts of ethanol-water mixed solvent.

[0049] The quaternized chitosan complexing agent is prepared by swelling chitosan with a degree of deacetylation of 84% and a molecular weight of 160 kDa in an acetic acid-ethanol mixed solvent, and then reacting with 2,3-epoxypropyltrimethylammonium chloride under heating and reflux conditions, followed by precipitation, washing and vacuum drying; the chitosan-cysteine derivative is prepared by swelling chitosan with a degree of deacetylation of 84% and a molecular weight of 95 kDa in an acidic aqueous solution, and then reacting with pre-activated L-cysteine under stirring conditions, followed by freeze-drying; the chitosan-glutathione derivative is prepared by swelling chitosan with a degree of deacetylation of 84% and a molecular weight of 95 kDa in an acidic aqueous solution, and then reacting with glutathione and a cross-linking agent under stirring at an appropriate pH, followed by freeze-drying.

[0050] The preparation method of the quaternized chitosan complexing agent is as follows: by weight, 39 parts of 1 wt.% acetic acid aqueous solution and 39 parts of ethanol are mixed to form a solvent system, 1.7 parts of chitosan is added and stirred for swelling for 138 min, then 3.8 parts of 2,3-epoxypropyltrimethylammonium chloride is added, and the reaction is carried out under reflux at 78 °C for 11 h. After the reaction is completed, the system is cooled to 26 °C, 590 parts of acetone is added to precipitate the product, the precipitate is collected and then centrifugally washed 4 times with a mixed solvent of anhydrous ether and acetone, where the volume ratio of anhydrous ether to acetone is 1:11, and finally vacuum dried at -0.09 MPa and 46 °C for 16 h to obtain the quaternized chitosan complexing agent.

[0051] The preparation method of the chitosan-cysteine derivative is as follows: by weight, 2.2 parts of chitosan is dispersed in 80 parts of 1.2 wt.% hydrochloric acid aqueous solution and stirred for swelling for 39 min to form a homogeneous solution; another 1.3 parts of L-cysteine is dissolved in 65 parts of deionized water, 0.2 part of 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride is added, and the activation time is controlled to be 19 min; the activated cysteine solution is slowly added dropwise to the chitosan solution, and the pH of the system is adjusted to 4.5 with 1 vol.% hydrochloric acid solution, and the reaction is continuously stirred at 30 °C for 5 h. After the reaction is completed, the solution is freeze-dried for 31 h to obtain the chitosan-cysteine derivative.

[0052] The preparation method of the chitosan-glutathione derivative is as follows: by weight, 0.3 parts are dispersed in 2.2 parts of 1.1 mol / L hydrochloric acid aqueous solution, 10 parts of deionized water are added to form a colloidal dispersion system with a polymer concentration of 1.0 wt.%, and the pH of the system is adjusted to 5.8 with 1 vol.% hydrochloric acid, then 1.9 parts of a glutathione aqueous solution with a concentration of 230 mg / mL are added; 0.2 parts of 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride and 0.08 parts of N-hydroxysuccinimide are added in sequence, the pH value is maintained at 5.9, and the reaction is magnetically stirred at 19 °C for 16 h; the reaction solution is freeze-dried at -76 °C and 0.02 MPa for 47 h to obtain the chitosan-glutathione derivative.

[0053] In the ethanol-water mixed solvent, the volume ratio of ethanol to water is 1:2.8; the solution conductivity of the copper deposition agent is controlled at 8 mS / cm; the copper deposition rate of the copper deposition agent is 1.9 μm / min.

[0054] The preparation method of an environment-friendly copper deposition agent in this example includes the following steps:

[0055] S1. According to the ratio, dissolve the quaternized chitosan complexing agent, chitosan-cysteine derivative and chitosan-glutathione derivative in the ethanol-water mixed solvent, and the dissolution process is carried out at a stirring rate of 460 rpm for 39 min, and the system temperature is controlled at 28 °C;

[0056] S2. Preparation of the prepolymer solution: Add tea polyphenols, dopamine, potassium citrate trihydrate, ascorbic acid and glucose to the dissolved system in sequence, maintain the temperature at 28 °C, and mix until completely dissolved at a stirring speed of 360 rpm, and the total addition time is controlled at 13 min;

[0057] S3. Preparation of the coating: Slowly add sodium alginate and sodium citrate, adjust the pH of the system to 5.1, continue to stir at a rate of 460 rpm for 39 min to ensure the uniformity and stability of the system. After the final solution is filtered through a 0.45 μm filter membrane, it is left to stand in the dark at 5 °C for 16 h to complete the aging process.

[0058] Example 3

[0059] An environment-friendly copper deposition agent, comprising the following raw materials in parts by weight: 12 parts of quaternized chitosan complexing agent, 8 parts of chitosan-cysteine derivative, 4.6 parts of chitosan-glutathione derivative, 4.4 parts of tea polyphenols, 4.6 parts of dopamine, 16 parts of potassium citrate trihydrate, 4 parts of ascorbic acid, 4 parts of glucose, 1.4 parts of sodium alginate, 1.4 parts of sodium citrate, and 68 parts of ethanol-water mixed solvent.

[0060] The quaternized chitosan complexing agent is prepared by swelling chitosan with a deacetylation degree of 89% and a molecular weight of 220 kDa in an acetic acid-ethanol mixed solvent, and then reacting with 2,3-epoxypropyltrimethylammonium chloride under heating and reflux conditions, followed by precipitation, washing, and vacuum drying; the chitosan-cysteine derivative is prepared by swelling chitosan with a deacetylation degree of 89% and a molecular weight of 140 kDa in an acidic aqueous solution, and then reacting with pre-activated L-cysteine under stirring conditions, followed by freeze-drying; the glycan-glutathione derivative is prepared by swelling chitosan with a deacetylation degree of 89% and a molecular weight of 140 kDa in an acidic aqueous solution, and then reacting with glutathione and a cross-linking agent under stirring at an appropriate pH, followed by freeze-drying.

[0061] The preparation method of the quaternized chitosan complexing agent is as follows: by weight, 48 parts of 1 wt.% acetic acid aqueous solution and 48 parts of ethanol are mixed to form a solvent system, 1.8 parts of chitosan is added and stirred for swelling for 156 min, then 4.1 parts of 2,3-epoxypropyltrimethylammonium chloride is added, and the reaction is carried out under reflux at 81 °C for 12 h. After the reaction is completed, the system is cooled to 28 °C, 680 parts of acetone is added to precipitate the product, the precipitate is collected and then centrifugally washed 4 times with a mixed solvent of anhydrous ether and acetone, where the volume ratio of anhydrous ether to acetone is 1:12, and finally vacuum dried at -0.09 MPa and 52 °C for 19 h to obtain the quaternized chitosan complexing agent.

[0062] The preparation method of the chitosan-cysteine derivative is as follows: by weight, 3.4 parts of chitosan is dispersed in 110 parts of 1.3 wt.% hydrochloric acid aqueous solution and stirred for swelling for 48 min to form a homogeneous solution; separately, 2.0 parts of L-cysteine is dissolved in 80 parts of deionized water, 0.3 part of 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride is added, and the activation time is controlled to be 24 min; the activated cysteine solution is slowly added dropwise to the chitosan solution, and the pH of the system is adjusted to 4.9 with 1 vol.% hydrochloric acid solution, and the reaction is continuously stirred at 34 °C for 6 h. After the reaction is completed, the solution is freeze-dried for 38 h to obtain the chitosan-cysteine derivative.

[0063] The preparation method of chitosan-glutathione derivative is as follows: by weight, 0.4 parts are dispersed in 2.5 parts of 1.1 mol / L hydrochloric acid aqueous solution, 12 parts of deionized water are added to form a colloidal dispersion system with a polymer concentration of 1.2 wt.%, and the pH of the system is adjusted to 6.1 with 1 vol.% hydrochloric acid, then 2.4 parts of glutathione aqueous solution with a concentration of 260 mg / mL are added; 0.2 parts of 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride and 0.11 parts of N-hydroxysuccinimide are added in sequence, the pH value is maintained at 6.0, and the reaction is magnetically stirred at 24 °C for 19 h; the reaction solution is freeze-dried at -82 °C and 0.03 MPa for 58 h to obtain chitosan-glutathione derivative.

[0064] In the ethanol-water mixed solvent, the volume ratio of ethanol to water is 1:3.5; the solution conductivity of the copper deposition agent is controlled at 11 mS / cm; the copper deposition rate of the copper deposition agent is 2.4 μm / min.

[0065] The preparation method of an environment-friendly copper deposition agent in this embodiment includes the following steps:

[0066] S1. According to the ratio, dissolve the quaternized chitosan complexing agent, chitosan-cysteine derivative and chitosan-glutathione derivative in the ethanol-water mixed solvent, and the dissolution process is carried out at a stirring rate of 520 rpm for 48 min, and the system temperature is controlled at 31 °C;

[0067] S2. Preparation of the prepolymer solution: Add tea polyphenols, dopamine, potassium citrate trihydrate, ascorbic acid and glucose to the dissolved system in sequence, maintain the temperature at 31 °C, and mix until completely dissolved at a stirring speed of 420 rpm, and the total addition time is controlled at 16 min;

[0068] S3. Prepare the coating: Slowly add sodium alginate and sodium citrate, adjust the pH of the system to 5.7, continue to stir at a rate of 520 rpm for 48 min to ensure the uniformity and stability of the system. After the final solution is filtered through a 0.45 μm filter membrane, it is left to stand in the dark at 6 °C for 19 h to complete the aging process.

[0069] Example 4

[0070] An environment-friendly copper deposition agent includes the following raw materials by weight: 15 parts of quaternized chitosan complexing agent, 10 parts of chitosan-cysteine derivative, 6.0 parts of chitosan-glutathione derivative, 6.0 parts of tea polyphenols, 6.0 parts of dopamine, 20 parts of potassium citrate trihydrate, 6 parts of ascorbic acid, 5 parts of glucose, 2 parts of sodium alginate, 2.0 parts of sodium citrate, and 80 parts of ethanol-water mixed solvent.

[0071] The quaternized chitosan complexing agent is prepared by swelling chitosan with a deacetylation degree of 95% and a molecular weight of 300 kDa in a mixed solvent of acetic acid - ethanol, and then reacting with 2,3 - epoxypropyltrimethylammonium chloride under heating and reflux conditions, followed by precipitation, washing and vacuum drying; the chitosan - cysteine derivative is prepared by swelling chitosan with a deacetylation degree of 95% and a molecular weight of 200 kDa in an acidic aqueous solution and then reacting with pre - activated L - cysteine under stirring conditions, followed by freeze - drying; the chitosan - glutathione derivative is prepared by swelling chitosan with a deacetylation degree of 95% and a molecular weight of 200 kDa in an acidic aqueous solution, and then reacting with glutathione and a cross - linker under stirring at an appropriate pH condition, followed by freeze - drying.

[0072] The preparation method of the quaternized chitosan complexing agent is as follows: by weight, 60 parts of 1 wt.% acetic acid aqueous solution and 60 parts of ethanol are mixed to form a solvent system, 2.0 parts of chitosan is added and stirred for swelling for 180 min, then 4.5 parts of 2,3 - epoxypropyltrimethylammonium chloride is added, and the reaction is carried out under reflux at 85 °C for 14 h. After the reaction is completed, the system is cooled to 30 °C, 800 parts of acetone is added to precipitate the product, and the precipitate is collected and centrifugally washed 5 times with a mixed solvent of anhydrous ether and acetone, where the volume ratio of anhydrous ether to acetone is 1:13. Finally, it is vacuum dried at - 0.10 MPa and 60 °C for 24 h to obtain the quaternized chitosan complexing agent.

[0073] The preparation method of the chitosan - cysteine derivative is as follows: by weight, 5.0 parts of chitosan is dispersed in 150 parts of 1.5 wt.% hydrochloric acid aqueous solution and stirred for swelling for 60 min to form a homogeneous solution; another 3.0 parts of L - cysteine is dissolved in 100 parts of deionized water, 0.5 part of 1 - ethyl - (3 - dimethylaminopropyl) carbodiimide hydrochloride is added, and the activation time is controlled for 30 min; the activated cysteine solution is slowly added dropwise to the chitosan solution, and the pH of the system is adjusted to 5.5 with 1 vol.% hydrochloric acid solution, and the reaction is continuously stirred at 40 °C for 8 h. After the reaction is completed, the solution is freeze - dried for 48 h to obtain the chitosan - cysteine derivative.

[0074] The preparation method of chitosan-glutathione derivative is as follows: by weight, 0.5 parts are dispersed in 3.0 parts of 1.2 mol / L hydrochloric acid aqueous solution, 15 parts of deionized water are added to form a colloidal dispersion system with a polymer concentration of 1.5 wt.%, and the pH of the system is adjusted to 6.5 with 1 vol.% hydrochloric acid, then 3.0 parts of glutathione aqueous solution with a concentration of 300 mg / mL are added; 0.3 parts of 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride and 0.15 parts of N-hydroxysuccinimide are added in sequence, the pH value is maintained at 6.2, and the reaction is magnetically stirred at 30 °C for 24 h; the reaction solution is freeze-dried at -90 °C and 0.05 MPa for 72 h to obtain chitosan-glutathione derivative.

[0075] In the ethanol-water mixed solvent, the volume ratio of ethanol to water is 1:4.5; the solution conductivity of the copper deposition agent is controlled at 15 mS / cm; the copper deposition rate of the copper deposition agent is 3.0 μm / min.

[0076] A preparation method of an environment-friendly copper deposition agent in this embodiment includes the following steps:

[0077] S1. According to the ratio, the quaternized chitosan complexing agent, chitosan-cysteine derivative and chitosan-glutathione derivative are dissolved in the ethanol-water mixed solvent, and the dissolution process is carried out at a stirring rate of 600 rpm for 60 min, and the system temperature is controlled at 35 °C;

[0078] S2. Preparation of the prepolymer solution: Tea polyphenols, dopamine, potassium citrate trihydrate, ascorbic acid and glucose are added to the dissolved system in sequence, the temperature is maintained at 35 °C, and the mixture is stirred at a speed of 500 rpm until completely dissolved, and the total addition time is controlled within 20 min;

[0079] S3. Preparation of the coating: Sodium alginate and sodium citrate are slowly added, the pH of the system is adjusted to 6.5, and the stirring is continued at a rate of 600 rpm for 60 min to ensure the uniformity and stability of the system. After the final solution is filtered through a 0.45 μm filter membrane, it is allowed to stand in the dark at 8 °C for 24 h to complete the aging process.

[0080] Comparative Example 1

[0081] It is basically the same as Example 1, the difference is that the quaternized chitosan complexing agent is not added, and only ordinary chitosan is used instead.

[0082] Comparative Example 2

[0083] It is basically the same as Example 1, the difference is that the chitosan-cysteine derivative is not added, and only ordinary chitosan is used instead.

[0084] Comparative Example 3

[0085] Basically the same as Example 1, except that chitosan-glutathione derivative is not added, and only ordinary chitosan is used instead.

[0086] Comparative Example 4

[0087] Basically the same as Example 1, except that the dosage of quaternized chitosan complexing agent is increased to 20 parts, exceeding the scope of the claims.

[0088] Comparative Example 5

[0089] Basically the same as Example 1, except that when preparing the quaternized chitosan complexing agent, the reflux reaction temperature is increased to 90 °C, exceeding the scope of the claims.

[0090] Comparative Example 6

[0091] Basically the same as Example 1, except that tea polyphenols and dopamine are not added.

[0092] Comparative Example 7

[0093] Basically the same as Example 1, except that the volume ratio of ethanol to water in the ethanol-water mixed solvent is 1:5.0, exceeding the scope of the claims.

[0094] Comparative Example 8

[0095] Basically the same as Example 1, except that 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride is not added as an activator during the preparation of chitosan-cysteine derivative.

[0096] Performance test:

[0097] Copper layer adhesion test: Referring to the standard method of ASTM D3359-17, electroless copper plating is carried out on the surface of a 100 mm × 100 mm FR-4 substrate, and the deposition thickness is controlled at 2 μm. The cross-cut method is adopted, and a 3M tape is used for peeling test. Observe with a magnifying glass within the cross-cut area, and evaluate the adhesion between the copper layer and the substrate according to the 0-5 level.

[0098] Copper layer uniformity and porosity test: Referring to the standard of IPC-TM-650 2.2.12, a scanning electron microscope (SEM) is used to observe the surface morphology of the deposited copper layer, and the composition distribution of the copper layer is analyzed by EDS energy spectrum. At the same time, electrochemical impedance spectroscopy (EIS) is used to evaluate the compactness of the copper layer.

[0099] Environmental friendliness assessment: Referring to the life cycle assessment method of ISO 14040, environmental indicators such as COD, BOD, and heavy metal ion content during the copper plating process are measured. Atomic absorption spectrometry (AAS) is used to detect the heavy metal content in the waste liquid, and the chemical oxygen demand (COD) is determined by the potassium dichromate method.

[0100] Corrosion resistance test of the coating: Referring to the ASTM B117-19 standard, the coated samples were placed in a 5wt.% sodium chloride salt spray test chamber at a temperature of 35±2 °C for 168 hours of accelerated corrosion testing. An electrochemical workstation was used to test the polarization curve and corrosion potential of the samples.

[0101] The performances of the environmentally friendly copper deposition agents of Examples 1 to 4 and Comparative Examples 1 to 8 are summarized in Table 1.

[0102] Table 1 Summary of the performances of the environmentally friendly copper deposition agents of Examples 1 to 4 and Comparative Examples 1 to 8

[0103]

[0104] The quaternized chitosan complexing agent is a key component for improving the adhesion and corrosion resistance of the copper layer. Its absence will lead to a significant decrease in these two performances; the cysteine derivative mainly affects the adhesion between the copper layer and the substrate and has a slight impact on other performances; the glutathione derivative has a relatively small impact on the copper deposition performance; when the dosage of the complexing agent exceeds the optimal range, the COD of the wastewater will increase; too high reaction temperature will affect the molecular structure and crosslinking degree of the product and reduce the compactness of the copper layer; tea polyphenols and dopamine are important components for improving corrosion resistance, but their reduction will instead decrease the COD value; the ratio of the ethanol-water mixed solvent has no obvious effect on the copper deposition performance; the use of the activator plays a key role in improving the adhesion and compactness of the copper layer. The lack of the activator will significantly reduce these two performance indicators.

[0105] Finally, it should be noted that the above examples are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to the above examples, those of ordinary skill in the art should understand that all equivalent structural transformations made under the concept of the present invention by using the content of the specification and drawings of the present invention should be covered within the protection scope of the claims of the present invention.

Claims

1. An environmentally friendly copper plating agent, characterized in that: The invention comprises the following raw materials in parts by weight: 8-15 parts of quaternized chitosan complexing agent, 5-10 parts of chitosan-cysteine ​​derivative, 2.5-6.0 parts of chitosan-glutathione derivative, 2.0-6.0 parts of tea polyphenols, 2.5-6.0 parts of dopamine, 10-20 parts of potassium citric acid trihydrate, 2-6 parts of ascorbic acid, 2-5 parts of glucose, 0.5-2 parts of sodium alginate, 0.5-2.0 parts of sodium citrate, and 50-80 parts of ethanol-water mixed solvent; The preparation method of the quaternary ammonium chitosan complexing agent is as follows: by weight, 30-60 parts of 1wt.% acetic acid aqueous solution and 30-60 parts of ethanol are mixed to form a solvent system, 1.5-2.0 parts of chitosan are added, stirred and swollen for 120-180 minutes, then 3.5-4.5 parts of 2,3-epoxypropyltrimethylammonium chloride are added, reflux reaction is carried out at 75-85°C for 10-14 hours, after the reaction is completed, the system is cooled to 25-30°C, 500-800 parts of acetone are added to precipitate the product, the precipitate is collected and then centrifuged and washed 3-5 times with a mixed solvent of anhydrous ether and acetone, wherein the volume ratio of anhydrous ether to acetone is 1:(10-13), and finally vacuum dried at -0.08-0.10MPa and 40-60°C for 12-24 hours to obtain the quaternary ammonium chitosan complexing agent; The preparation method of the chitosan-cysteine ​​derivative is as follows: by weight, 1.0-5.0 parts of chitosan are dispersed in 50-150 parts of 1.0-1.5wt.% hydrochloric acid aqueous solution, and stirred and swollen for 30-60 minutes to form a homogeneous solution; 0.5-3.0 parts of L-cysteine ​​are dissolved in 50-100 parts of deionized water, 0.1-0.5 parts of 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride are added, and the activation time is controlled to be 15-30 minutes; the activated L-cysteine ​​solution is slowly added dropwise to the chitosan solution, the pH of the system is adjusted to 4.0-5.5 with 1vol.% hydrochloric acid solution, and the reaction is continuously stirred at 25-40°C for 4-8 hours. After the reaction is completed, the solution is freeze-dried for 24-48 hours to obtain the chitosan-cysteine ​​derivative; The preparation method of the chitosan-glutathione derivative is as follows: by weight, 0.2-0.5 parts of chitosan are dispersed in 1.8-3.0 parts of 1.0-1.2 mol / L hydrochloric acid aqueous solution, 8-15 parts of deionized water are added to form a colloidal dispersion system with a polymer concentration of 0.8%-1.5wt.%, and 1.5-3.0 parts of 200-300 mg / mL of 1% hydrochloric acid are added to adjust the pH of the system to 5.5-6.

5. Glutathione aqueous solution; adding 0.1-0.3 parts of 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride and 0.05-0.15 parts of N-hydroxysuccinimide in sequence, maintaining the pH value at 5.8-6.2, and reacting under magnetic stirring at 15-30°C for 12-24 hours; freeze-drying the solution after the reaction at -70--90°C and 0.01-0.05MPa for 36-72 hours to obtain a chitosan-glutathione derivative; The volume ratio of ethanol to water in the ethanol-water mixed solvent is 1:(2.0-4.5).

2. An environmentally friendly copper deposition agent as claimed in claim 1, characterized in that: The quaternized chitosan complexing agent is prepared by swelling chitosan with a deacetylation degree of 80-95% and a molecular weight of 100-300 kDa in an acetic acid-ethanol mixed solvent, reacting with 2,3-epoxypropyltrimethylammonium chloride under heating reflux conditions, and then precipitating, washing and vacuum drying. The chitosan-cysteine ​​derivative is prepared by swelling chitosan with a deacetylation degree of 80-95% and a molecular weight of 50-200 kDa in an acidic aqueous solution, reacting with activated L-cysteine ​​under stirring conditions, and freeze-drying; The chitosan-glutathione derivative is prepared by swelling chitosan with a deacetylation degree of 80-95% and a molecular weight of 50-200 kDa in an acidic aqueous solution, stirring and reacting with glutathione and a cross-linking agent under suitable pH conditions, and freeze-drying.

3. An environmentally friendly copper deposition agent as claimed in claim 1, characterized in that: The solution conductivity of the copper plating agent is controlled at 5-15 mS / cm.

4. An environmentally friendly copper deposition agent as claimed in claim 1, characterized in that: The copper deposition rate of the copper deposition agent is 1.5-3.0 μm / min.

5. A method for preparing an environmentally friendly copper deposition agent as claimed in any one of claims 1 to 4, characterized in that: The following steps are involved: S1. According to the ratio, the quaternary ammonium chitosan complexing agent, chitosan-cysteine ​​derivative and chitosan-glutathione derivative are dissolved in an ethanol-water mixed solvent, and the dissolution process is carried out at a stirring rate of 400-600 rpm for 30-60 min, and the system temperature is controlled at 25-35°C; S2. Preparation of prepolymer solution: tea polyphenols, dopamine, potassium citrate trihydrate, ascorbic acid and glucose were added to the dissolved system in sequence, the temperature was maintained at 25 to 35°C, and the stirring speed was 300 to 500 rpm until completely dissolved. The total addition time was controlled within 10 to 20 min; S3. Prepare the coating: slowly add sodium alginate and sodium citrate, adjust the pH of the system to 4.5-6.5, continue stirring at 400-600 rpm for 30-60 min to ensure that the system is uniform and stable. After the final solution is filtered through a 0.45 μm filter membrane, stand at 4-8°C in the dark for 12-24 h to complete the aging process.

6. Use of the environmentally friendly copper deposition agent as claimed in any one of claims 1 to 4 or the environmentally friendly copper deposition agent prepared by the preparation method as claimed in claim 5 in the manufacture of flexible electronic devices.

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