Preparation method of cyanide-free alkaline silver electroplating additive for advanced packaging and silver electroplating liquid for advanced packaging

Abstract

The invention discloses a preparation method of a cyanide-free alkaline silver electroplating additive for advanced packaging and a silver electroplating solution for advanced packaging. The additive is a mixture of an o-benzoyl sulfonyl imide polyoxypropylene / vinyl ether propane sulfonate aqueous solution and / or a beta-naphthyl sulfonyl imide polyoxypropylene / vinyl ether propane sulfonate aqueous solution. The additive is matched with the silver salt, the complexing agent, the brightener and the pH regulator, a bright, fine, defect-free and spot-free silver plating layer can be obtained, the additive has the effect of reducing the internal stress of the silver plating layer, meanwhile, the additive has the characteristics of a surfactant, the surface tension between the plating layer and a substrate is reduced, and then the binding force between the plating layer and the substrate is enhanced. A cyanide-free system is safe and environment-friendly, and pollution is effectively reduced.

Description

Technical Field

[0001] This invention relates to a method for preparing a cyanide-free alkaline silver plating additive for advanced packaging and a silver plating solution for advanced packaging, belonging to the field of advanced packaging technology. Background Technology

[0002] Silver plating, with its unique combination of properties, is playing an increasingly important role in advanced packaging, especially in high-power, high-frequency, and high-reliability applications. This is due to its excellent conductivity, antibacterial properties, and chemical stability, as well as its relatively low cost compared to other precious metals. However, traditional cyanide-based silver plating processes pose serious environmental pollution problems, as cyanide is a highly toxic chemical that poses a serious threat to the environment and human health. Therefore, developing cyanide-free silver plating processes has become an inevitable trend in the industry.

[0003] Currently, although various cyanide-free silver plating systems exist, such as thiosulfate silver plating and succinimide silver plating, these systems still have some drawbacks in terms of solution stability, process performance, and coating performance. These include unstable plating solution composition, easy volatilization and discoloration, poor solution dispersion, and low cathode current density. Furthermore, in the semiconductor packaging field, microscopic defects in the coating structure can amplify exponentially during subsequent packaging processes, affecting the overall yield of chip packaging.

[0004] Therefore, developing a cyanide-free alkaline silver plating additive that can provide a bright, fine, defect-free, nodule-free silver plating layer, while also possessing good dispersion and coverage capabilities, high stability, high-speed electroplating of thick silver layers, no stress deformation, and excellent plating uniformity, has become a key research focus and challenge. This not only meets environmental protection requirements but also satisfies the growing demand for conductivity and stability in high-precision modules used in electronics, semiconductors, and other fields. Summary of the Invention

[0005] Based on the shortcomings of the prior art, the technical problem solved by the present invention is to provide a cyanide-free alkaline silver plating additive for advanced semiconductor packaging, which has the function of reducing the internal stress of the plating layer, and at the same time has the characteristics of surfactant, which is beneficial to reduce the interfacial surface tension, increase the cathode polarization, refine the crystals, and thus enhance the bonding force with the substrate. Moreover, it is an environmentally friendly silver plating solution that does not contain cyanide.

[0006] A cyanide-free alkaline silver plating additive, wherein the additive is an aqueous solution of o-benzoylsulfonylimide polyoxypropylene / ethylene ether propane sulfonate and / or an aqueous solution of β-naphthoylsulfonylimide polyoxypropylene / ethylene ether propane sulfonate, and the general structural formulas of o-benzoylsulfonylimide polyoxypropylene / ethylene ether propane sulfonate and β-naphthoylsulfonylimide polyoxypropylene / ethylene ether propane sulfonate are: and , As mentioned above, a=c=0~3, b=d=3~20, and R is any one of K and Na.

[0007] The structural formulas of the o-benzoylsulfonylimide and β-naphthoylsulfonylimide are as follows: and .

[0008] The sulfonate is any one or a mixture of two of potassium sulfonate or sodium sulfonate.

[0009] The additive is selected from one or a mixture of two aqueous solutions of o-benzoylsulfonylimide polyoxypropylene / ethylene ether propane sulfonate potassium salt, o-benzoylsulfonylimide polyoxypropylene / ethylene ether propane sulfonate sodium salt, o-benzoylsulfonylimide polyoxyethylene ether propane sulfonate potassium salt, o-benzoylsulfonylimide polyoxyethylene ether propane sulfonate sodium salt, β-naphthoylsulfonylimide polyoxypropylene / ethylene ether propane sulfonate potassium salt, β-naphthoylsulfonylimide polyoxypropylene / ethylene ether propane sulfonate sodium salt, β-naphthoylsulfonylimide polyoxyethylene ether propane sulfonate potassium salt, and β-naphthoylsulfonylimide polyoxyethylene ether propane sulfonate sodium salt.

[0010] This invention also provides a method for preparing a copper plating solution without additives, comprising the following steps: Step 1: Solid o-benzoylsulfonylimide or β-naphthoylsulfonylimide are respectively added to a high-pressure reactor, purged with nitrogen, heated and stirred to melt, dehydrated under negative pressure, and then added to propylene oxide and ethylene oxide respectively under nitrogen protection to obtain o-benzoylsulfonylimide polyoxypropylene / ethylene ether or β-naphthoylsulfonylimide polyoxypropylene / ethylene ether. Step 2: Transfer the o-benzoylsulfonylimide polyoxypropylene / ethylene ether or β-naphthoylsulfonylimide polyoxypropylene / ethylene ether obtained in Step 1 into an atmospheric pressure reactor, add an alkaline catalyst, and react at a certain temperature. After the reaction is completed, add 1,3-propane sulfonyl lactone dropwise under a closed negative pressure state and stir the reaction to obtain o-benzoylsulfonylimide polyoxypropylene / ethylene ether sulfonate or β-naphthoylsulfonylimide polyoxypropylene / ethylene ether sulfonate. Step 3: The o-benzoylsulfonylimide polyoxypropylene / ethylene ether sulfonate or β-naphthoylsulfonylimide polyoxypropylene / ethylene ether sulfonate obtained in Step 2 are subjected to solvent extraction, distillation to remove salt, and vacuum distillation to remove solvent, respectively. The product obtained after distillation is adjusted with water to obtain cyanide-free alkaline electroplating silver additive. The o-benzoylsulfonylimide polyoxypropylene / ethylene ether sulfonate obtained after desalting is designated as cyanide-free alkaline electroplating silver additive (I); the β-naphthoylsulfonylimide polyoxypropylene / ethylene ether sulfonate obtained after desalting is designated as cyanide-free alkaline electroplating silver additive (II).

[0011] Cyanide-free alkaline silver plating additive (I) and cyanide-free alkaline silver plating additive (II) are mixed to obtain cyanide-free alkaline silver plating additive (III). The mass ratio of cyanide-free alkaline silver plating additive (I) to cyanide-free alkaline silver plating additive (II) is 1:0.25~3.35.

[0012] In step one, the heating and stirring temperature range is 115~145℃, and the negative pressure dehydration conditions are 120~145℃ and negative pressure range of 20~500Pa for 3~5 hours until the moisture content is less than 0.01% (removal of free water and bound water).

[0013] In step one, the mass ratio of o-benzoylsulfonylimide and / or β-naphthoylsulfonylimide, propylene oxide, and ethylene oxide is 1:0~1.0:0.5~5.0; the addition polymerization reaction pressure is 0.2~0.6MPa, the reaction temperature is 125~225℃, and the stirring and heat preservation reaction time is 10~24 hours.

[0014] The amount of propylene oxide is 0, or the amount of o-benzoylsulfonylimide and / or β-naphthoylsulfonylimide is less than or equal to 1.

[0015] When the value is 0, the product obtained is any one of the following: potassium salt of o-benzoylsulfonimide polyoxyethylene ether propane sulfonate, sodium salt of o-benzoylsulfonimide polyoxyethylene ether propane sulfonate, potassium salt of β-naphthoylsulfonimide polyoxyethylene ether propane sulfonate, and sodium salt of β-naphthoylsulfonimide polyoxyethylene ether propane sulfonate. When the dosage is less than or equal to 1, the product obtained is potassium salt of o-benzoylsulfonylimide polyoxypropylene / ethylene ether propane sulfonate. Any one of the following: sodium salt of o-benzoylsulfonylimide polyoxypropylene / ethylene ether propane sulfonate, potassium salt of β-naphthoylsulfonylimide polyoxypropylene / ethylene ether propane sulfonate, and sodium salt of β-naphthoylsulfonylimide polyoxypropylene / ethylene ether propane sulfonate.

[0016] In step two, the alkaline catalyst includes any one or two of potassium hydroxide, sodium hydroxide, potassium methoxide, sodium methoxide, potassium tert-butoxide, and sodium tert-butoxide. The mass fraction of the alkaline catalyst is 0.01~0.04%, and the reaction is carried out under a negative pressure of 50~550Pa, at 65~85℃, for 2~6 hours.

[0017] In step two, the mass ratio of o-benzoylsulfonylimide polyoxypropylene / ethylene ether or β-naphthoylsulfonylimide polyoxypropylene / ethylene ether to 1,3-propanesulfonyl lactone is 1:0.1~0.45. 1,3-propanesulfonyl lactone is added dropwise while maintaining a closed negative pressure state. The reaction is carried out at 90~135℃ under pressure for 5~25 hours, with the negative pressure range being 100~500Pa throughout.

[0018] In step three, the cyanide-free alkaline electroplating silver additive (I) and cyanide-free alkaline electroplating silver additive (II) are mixed with pure water to adjust the solid content to 75±5%.

[0019] In step three, the solvent used for solvent extraction is selected from any one of ethylene glycol ether, light aromatic hydrocarbon solvent oil, N,N-dimethylacetamide, etc.; the amount of solvent used is 2 to 4 times the volume of o-benzoylsulfonylimide polyoxypropylene / ethylene ether sulfonate or β-naphthoylsulfonylimide polyoxypropylene / ethylene ether sulfonate, and the extraction is performed 3 to 5 times; the cyanide-free alkaline electroplating silver additive (III) is adjusted to a solid content of 75±5% with pure water.

[0020] Another technical solution of the present invention is to provide an advanced packaging silver plating solution, including the cyanide-free alkaline silver plating additive, or including the cyanide-free alkaline silver plating additive prepared by the method.

[0021] Another technical solution of this invention involves the application of cyanide-free alkaline silver plating additives in the preparation of silver plating solutions for advanced packaging. Working synergistically with other additives, a monomolecular barrier layer is generated at the crystal nucleation site, promoting uniform distribution of crystal nuclei, refining grains, and forming a dense silver plating layer. Simultaneously, the molecules modified with epoxy and 1,3-propanesulfonyl lactone significantly enhance wettability and hydrolysis resistance, effectively improving the overall stability of the plating solution.

[0022] Another technical solution of the present invention is to provide a silver plating solution for advanced packaging, wherein the silver plating solution for advanced packaging contains the aforementioned cyanide-free alkaline silver plating additive, or contains the prepared cyanide-free alkaline silver plating additive.

[0023] An advanced encapsulation silver plating solution composition, the composition comprising a cyanide-free alkaline silver plating additive, a silver salt, a complexing agent, a brightener, and a pH adjuster.

[0024] The cyanide-free alkaline silver plating additive is the cyanide-free alkaline silver plating additive mentioned above, or the cyanide-free alkaline silver plating additive prepared above, and the dosage is 50~150mg / L.

[0025] The silver salt is silver methanesulfonate, with a dosage of 30-90 g / L; the complexing agent is 5,5-dimethylhydantoin (DMH), potassium tartrate, succinimide, and potassium citrate, with a dosage of 50-200 g / L; the brightening agent is polyethyleneimine with a molecular weight of 600-1800, with an addition amount of 50-500 mg / L; the pH adjuster is 40% liquid alkali, the components of which are potassium carbonate and potassium hydroxide in a mass ratio of 1:1, and the pH value is adjusted to a range of 9.0-11.0.

[0026] Compared with the prior art, the technical solution of the present invention has the following beneficial effects: The additives in this invention exhibit excellent wetting synergy in silver plating solutions. The structurally modified additive molecules possess surface activity, enhancing wetting on the substrate. Simultaneously, utilizing the adsorption mechanism of active groups, a monomolecular barrier layer is generated at grain formation sites, promoting orderly crystal growth and achieving an inhibition-acceleration mechanism. This refines the plating layer crystals, resulting in a microscopic leveling effect. Furthermore, it demonstrates excellent resistance to hydrolysis in strongly alkaline systems, maintaining the stability of the plating solution. The cyanide-free system is safe and environmentally friendly, effectively reducing pollution.

[0027] The above description is merely an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention and to implement it in accordance with the contents of the specification, and to make the above and other objects, features and advantages of the present invention more apparent and understandable, the following detailed description is provided in conjunction with preferred embodiments. Attached Figure Description

[0028] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings of the embodiments will be briefly described below.

[0029] Figure 1 The SEM test results of the electroplating effect of the advanced encapsulated cyanide-free alkaline silver plating solution (1) of Example 1 are shown.

[0030] Figure 2 The SEM test results of the electroplating effect of the advanced encapsulated cyanide-free alkaline silver plating solution (2) of Example 1 are shown.

[0031] Figure 3 The infrared spectrum of sodium benzoyl sulfonyl imide polyoxypropylene / ethylene ether sulfonate salt-3+20, an additive for advanced encapsulation of cyanide-free alkaline silver plating solution in Example 2, is shown.

[0032] Figure 4 The infrared spectrum of β-naphthoyl sulfonyl imide polyoxypropylene / ethylene ether propane sulfonate potassium salt-3+14, an additive for advanced encapsulation of cyanide-free alkaline silver plating solution in Example 6, is shown.

[0033] Figure 5 In Figure a, we see a schematic diagram of the effect of electroplated silver coating; in Figure b, we see a schematic diagram of the effect of white grid knife test; and in Figure c, we see a schematic diagram of the effect of white grid knife test.

[0034] Figure 6 This is a schematic diagram of the test results for the white grid knife coating. In the diagram, 1-A is a qualified test result, 2-A is a test result of one type of failure, 2-B is a test result of another type of failure, and 2-C is a test result of yet another type of failure. Detailed Implementation

[0035] The specific embodiments of the present invention are described in detail below.

[0036] Example 1 Preparation process of additive A: Clean and dry the jacketed and stirred autoclave. Add solid o-benzoylsulfonylimide into the autoclave, purge with nitrogen three times, start stirring, heat to 115℃, and dehydrate at 120-125℃ under a negative pressure of 200-500 Pa for 4 hours. The moisture content is measured to be 0.001%. Pressurize with nitrogen to 0.4-0.6 MPa, heat to 125℃, and slowly add 20 mol of ethylene oxide (EO). Maintain the reaction at 125-155℃ and 0.4-0.6 MPa for 12 hours. Transfer the resulting reaction solution to a four-necked round-bottom flask equipped with a thermometer and a mechanical stirrer, start stirring, and heat to 65℃ in a water bath. Add 0.01% solid KOH, and react at a constant temperature of 65-70℃ under a negative pressure of 50-150 Pa for 2 hours. Then, 1.005 mol of 1,3-propanesulfonyl lactone (1,3-PS) was added dropwise under a negative pressure of 100 Pa to 200 Pa, and the reaction was maintained at 90 to 100 °C for 25 hours. The mixture was then cooled to room temperature (25 °C) and extracted three times with twice the volume of ethylene glycol ether to remove small molecule salts. The solvent was then recovered by vacuum distillation to obtain potassium benzoylsulfonylimide polyoxyethylene ether sulfonate-20. Finally, water was added and stirred until homogeneous, adjusting the solid content to 75%, which was designated as additive A.

[0037] The structural formula of additive A is shown below: Additive A (potassium benzoyl sulfonyl imide polyoxyethylene ether sulfonate-20) A cyanide-free alkaline silver plating solution was prepared using additive A (1):

[0038] Comparative Example 1 uses additive-free A to prepare cyanide-free alkaline silver plating solution (2):

[0039] Preparation method of cyanide-free alkaline silver plating solution for advanced packaging (taking the preparation of 1L plating solution as an example): First, add a certain amount of deionized water to a 1L beaker, then slowly add 100mL of pH adjuster (a 40% potassium carbonate and potassium hydroxide alkaline solution with a mass ratio of 1:1), stir well, add the pre-weighed complexing agent, stir thoroughly to dissolve, and then add more pH adjuster (a 40% potassium carbonate and potassium hydroxide alkaline solution with a mass ratio of 1:1) to adjust the pH to 9.5 (room temperature 25℃). Next, slowly add silver salt in batches, stirring thoroughly to dissolve. Using a 100~1000μL pipette, add measured amounts of pre-prepared aqueous solutions of brightener and additives. Finally, add deionized water to a final volume of 950mL, adjust the pH to the desired range, cool to room temperature, and circulate the solution through a 1μm filter for 10 minutes. Dilute to volume in a 1L volumetric flask to obtain the cyanide-free alkaline silver plating solution for advanced encapsulation. (Note: All raw materials are AR grade.) The examples were tested for electroplating applications, and the specific methods are as follows: An 8-inch pure copper wafer with a 1μm copper seed layer was uniformly cut into 40mm x 30mm rectangles, resulting in an actual electroplating area of ​​30mm x 30mm. Electroplating tests were conducted in a vertical electroplating bath. The same current density and electroplating time (1 ASD 900 s) were used at temperatures ranging from 45 to 50°C. After electroplating, the surface morphology of the plating layer was observed using SEM, and the adhesion of the plating layer was tested using the white grid method to determine the influence of additives on the morphology and adhesion of the plating layer.

[0040] Figure 1 The SEM test results of the electroplating effect of the advanced encapsulated cyanide-free alkaline silver electroplating solution (1) of Example 1 are shown. Under a 5KX microscope, the silver coating grains are fine and uniformly arranged, with no microscopic defects, which proves that the present invention has a good crystal refinement effect in the cyanide-free alkaline silver electroplating solution.

[0041] Figure 2 The SEM test results of the advanced encapsulated cyanide-free alkaline silver plating solution (2) of Example 1 are shown. Under a 5KX microscope, the silver plating layer has large grains, which are distributed in clusters and have microscopic defects, proving that the present invention has a good microscopic leveling effect in the cyanide-free alkaline silver plating solution.

[0042] Figure 1 and Figure 2 The comparison shows that the additives play a good role in inhibiting active sites in the cyanide-free alkaline silver plating solution formulation, refining crystals, and helping to disperse the internal stress of the plating layer.

[0043] Example 2 Preparation process of additive B: A jacketed and stirred autoclave was cleaned and dried. Solid o-benzoylsulfonylimide was added to the autoclave, and the mixture was purged with nitrogen three times. Stirring was then started, and the temperature was raised to 120°C. Dehydration was carried out at a negative pressure of 100-400 Pa for 3 hours at 120-140°C, and the moisture content was measured to be 0.002%. Nitrogen was then pressurized to 0.2 MPa, and the temperature was raised to 130°C. 3 mol of propylene oxide (PO) and 20 mol of ethylene oxide (EO) were slowly added. The reaction was maintained at 0.2-0.4 MPa for 20 hours at 130-200°C. The mixture was then cooled to 60°C and discharged to obtain o-benzoylsulfonylimide polyoxypropylene / ethylene ether-3+20. The above steps were repeated in a high-pressure autoclave to prepare β-naphthoylsulfonylimide polyoxypropylene / ethylene ether-3+20. The obtained o-benzoylsulfonylimide polyoxypropylene / ethylene ether-3+20 was transferred to a four-necked round-bottom flask equipped with a thermometer and a mechanical stirrer. Stirring was started, and the temperature was raised to 70°C in a water bath. 0.02% solid NaOH was added, and the reaction was carried out at a constant temperature of 70-75°C for 3 hours under a negative pressure of 100-200 Pa. Then, 1.01 mol of 1,3-propanesulfonyl lactone (1,3-PS) was added dropwise while maintaining a negative pressure of 150-300 Pa, and the reaction was carried out at 95-105°C for 10 hours. The mixture was cooled to room temperature (25°C), and extracted four times with 3 volumes of light aromatic hydrocarbon solvent oil to remove small molecule salts. The solvent was then recovered by vacuum distillation to obtain sodium o-benzoylsulfonylimide polyoxypropylene / ethylene ether sulfonate-3+20. Finally, water was added and stirred until homogeneous, adjusting the solid content to 74.5%, which was designated as additive (I) B. Repeat the above steps, adding solid potassium methoxide to the β-naphthoylsulfonylimide polyoxypropylene / ethylene ether-3+20 obtained from the reaction, and performing the remaining operations as above, to obtain β-naphthoylsulfonylimide polyoxypropylene / ethylene ether sulfonate potassium salt-3+20, denoted as additive (II) B. Mix additive (I) B and additive (II) B at a mass ratio of 1:0.25 until homogeneous to obtain the final product, denoted as additive B.

[0044] The structural formulas of Additive (I) B and Additive (II) B are shown below: Additive (I) B (sodium benzoyl sulfonyl imide polyoxypropylene / ethylene ether sulfonate salt-3+20); and Additive (II) B (β-naphthoyl sulfonyl imide polyoxypropylene / ethylene ether propane sulfonate potassium salt-3+20).

[0045] A cyanide-free alkaline silver plating solution was prepared using additive B.

[0046] The preparation method of the cyanide-free alkaline silver plating solution for advanced packaging is the same as in Example 1.

[0047] Example 3 Preparation process of additive C: Clean and dry a jacketed and stirred autoclave. Add solid o-benzoylsulfonylimide into the autoclave, purge with nitrogen three times, start stirring, heat to 125℃, and dehydrate at a negative pressure of 50-300 Pa for 5 hours at 125-140℃, with a moisture content of 0.0011%. Pressurize with nitrogen to 0.3 MPa, heat to 135℃, and slowly add 3 mol of propylene oxide (PO) and 3 mol of ethylene oxide (EO). Maintain the reaction at 0.3-0.5 MPa and 135-210℃ for 10 hours. Cool to 60℃ and discharge to obtain o-benzoylsulfonylimide polyoxypropylene / ethylene ether-3+3. Repeat the above steps to prepare β-naphthoylsulfonylimide polyoxyethylene ether-20 in a high-pressure reactor.

[0048] The obtained o-benzoylsulfonylimide polyoxypropylene / ethylene ether-3+3 was transferred to a four-necked round-bottom flask equipped with a thermometer and a mechanical stirrer. Stirring was started, and the temperature was raised to 75°C in a water bath. 0.03% solid potassium methoxide was added, and the reaction was carried out at a constant temperature of 75-85°C for 4 hours under a negative pressure of 200-400 Pa. Then, 1.015 mol of 1,3-propanesulfonyl lactone (1,3-PS) was added dropwise while maintaining a negative pressure of 200-350 Pa, and the reaction was carried out at 100-115°C for 15 hours. The mixture was cooled to room temperature (25°C), and extracted five times with 4 volumes of N,N-dimethylacetamide to remove small molecule salts. The solvent was then recovered by vacuum distillation to obtain o-benzoylsulfonylimide polyoxypropylene / ethylene ether sulfonate potassium salt-3+3. Finally, water was added and stirred until homogeneous, adjusting the solid content to 76%, and this was designated as additive (I) C. Repeat the above steps, add solid sodium methoxide to the β-naphthoylsulfonylimide polyoxyethylene ether-20 obtained from the reaction, and perform the remaining operations as above to obtain β-naphthoylsulfonylimide polyoxypropylene / ethylene ether sulfonate sodium salt-20, denoted as additive (II) C.

[0049] Mix additive (I) C and additive (II) C at a mass ratio of 1:3.35 until homogeneous to obtain the final product, which is denoted as additive C.

[0050] The structural formulas of Additive (I) C and Additive (II) C are shown below: Additive (I) C (potassium salt of o-benzoylsulfonylimide polyoxypropylene / ethylene ether sulfonate-3+3); and Additive (II) C (β-naphthoyl sulfonyl imide polyoxyethylene ether propane sulfonate sodium salt-20).

[0051] A cyanide-free alkaline silver plating solution was prepared using additive C.

[0052] The preparation method of the cyanide-free alkaline silver plating solution for advanced packaging is the same as in Example 1.

[0053] Example 4 Preparation process of additive D: Clean and dry a jacketed and stirred autoclave. Add solid o-benzoylsulfonylimide into the autoclave, purge with nitrogen three times, start stirring, heat to 130℃, and dehydrate at a negative pressure of 20-250 Pa for 3.5 hours at 130-145℃, with a moisture content of 0.0012%. Pressurize with nitrogen to 0.2 MPa, heat to 140℃, and slowly add 1 mol of propylene oxide (PO) and 15 mol of ethylene oxide (EO). Maintain the reaction at 0.2-0.5 MPa and 140℃ for 24 hours. Cool to 60℃ and discharge to obtain o-benzoylsulfonylimide polyoxypropylene / ethylene ether-1+15.

[0054] Repeat the above steps to prepare β-naphthylsulfonylimide polyoxyethylene ether-19 in a high-pressure reactor. Transfer the obtained o-benzoylsulfonylimide polyoxypropylene / ethylene ether-1+15 to a four-necked round-bottom flask equipped with a thermometer and mechanical stirrer. Start the stirrer and heat the mixture in a water bath to 80°C. Add 0.04% solid potassium tert-butoxide and react at a constant temperature of 80-85°C for 6 hours under a negative pressure of 250-550 Pa. Then, while maintaining a negative pressure of 300-500 Pa, add 1.035 mol of 1,3-propanesulfonyl lactone (1,3-PS) dropwise and react at 110-125°C for 20 hours. Cool to room temperature (25°C) and extract the product three times with 3 volumes of light aromatic hydrocarbon solvent oil to remove small molecule salts. Then, recover the solvent by vacuum distillation to obtain sodium o-benzoylsulfonylimide polyoxypropylene / ethylene ether sulfonate-1+15. Finally, add water and stir well to adjust the solid content to 77.5%, and record it as additive (I) D.

[0055] Repeat the above steps, add solid sodium methoxide to the β-naphthoylsulfonylimide polyoxyethylene ether-19 obtained from the reaction, and perform the remaining operations as above to obtain sodium salt of β-naphthoylsulfonylimide polyoxyethylene ether sulfonate-19, which is designated as additive (II) D.

[0056] Mix additive (I) D and additive (II) D at a mass ratio of 1:1 to obtain the final product, which is denoted as additive D.

[0057] The structural formulas of Additive (I) D and Additive (II) D are shown below: Additive (I) D (potassium benzoyl sulfonyl imide polyoxypropylene / ethylene ether propane sulfonate - 1+15); and Additive (II) D (β-naphthoylsulfonylimide polyoxyethylene ether sulfonate sodium salt-19).

[0058] A cyanide-free alkaline silver plating solution was prepared using additive D.

[0059] The preparation method of the cyanide-free alkaline silver plating solution for advanced packaging is the same as in Example 1.

[0060] Example 5 Preparation process of additive E: Clean and dry a jacketed and stirred autoclave. Add solid o-benzoylsulfonylimide into the autoclave, purge with nitrogen three times, start stirring, heat to 120℃, and dehydrate at a negative pressure of 50-250 Pa for 4.5 hours at 120-145℃, with a moisture content of 0.0001%. Pressurize with nitrogen to 0.4 MPa, heat to 160℃, and slowly add 2 mol of propylene oxide (PO) and 18 mol of ethylene oxide (EO). Maintain the reaction at 0.4-0.6 MPa for 14 hours at 160-225℃. Cool to 60℃ and discharge to obtain o-benzoylsulfonylimide polyoxypropylene / ethylene ether-2+18.

[0061] Repeat the above steps to prepare β-naphthylsulfonylimide polyoxypropylene / ethylene ether-2+15 in a high-pressure reactor. Transfer the obtained o-benzoylsulfonylimide polyoxypropylene / ethylene ether-2+18 to a four-necked round-bottom flask equipped with a thermometer and mechanical stirrer. Start the stirrer and heat the mixture to 75°C in a water bath. Add 0.022% solid potassium hydroxide and react at a constant temperature of 75-85°C for 3 hours under a negative pressure of 100-400 Pa. Then, while maintaining a negative pressure of 100-250 Pa, add 1.1 mol of 1,3-propanesulfonyl lactone (1,3-PS) dropwise and react at 115-135°C for 5 hours. Cool to room temperature (25°C) and extract the product four times with 2 volumes of N,N-dimethylacetamide to remove small molecule salts. Then, recover the solvent by vacuum distillation to obtain sodium o-benzoylsulfonylimide polyoxypropylene / ethylene ether sulfonate-2+18.

[0062] Finally, add water and stir until homogeneous, adjusting the solid content to 70%, and label this as Additive (I) E. Repeat the above steps, adding solid sodium tert-butoxide to the β-naphthoylsulfonylimide polyoxypropylene / ethylene ether-2+15 obtained from the reaction, and performing the remaining operations as above, to obtain sodium β-naphthoylsulfonylimide polyoxypropylene / ethylene ether sulfonate-2+15, labeled as Additive (II) E. Mix Additive (I) E and Additive (II) E at a mass ratio of 1:2 until homogeneous to obtain the final product, labeled as Additive E.

[0063] The structural formulas of Additive (I) E and Additive (II) E are shown below: Additive (I) E (potassium benzoyl sulfonyl imide polyoxypropylene / ethylene ether propane sulfonate-2+18); and Additive (II) E (β-naphthoyl sulfonyl imide polyoxypropylene / ethylene ether propane sulfonate sodium salt-2+15).

[0064] A cyanide-free alkaline silver plating solution was prepared using additive E.

[0065] The preparation method of the cyanide-free alkaline silver plating solution for advanced packaging is the same as in Example 1.

[0066] Example 6 Preparation process of additive F: Clean and dry a jacketed and stirred autoclave. Add solid β-naphthylsulfonylimide to the autoclave, purge with nitrogen three times, start stirring, and heat to 115℃. Dehydrate at 120-135℃ under a negative pressure of 20-350 Pa for 3.5 hours, and the moisture content is measured to be 0.0013%. Pressurize with nitrogen to 0.2 MPa, heat to 195℃, and slowly add 3 mol of propylene oxide (PO) and 14 mol of ethylene oxide (EO). React at 195-225℃ under a pressure of 0.2-0.4 MPa for 13 hours. Transfer the resulting reaction solution to a four-necked round-bottom flask equipped with a thermometer and a mechanical stirrer, start stirring, and heat to 65℃ in a water bath. Add 0.025% solid sodium hydroxide, and react at a constant temperature of 65-75℃ under a negative pressure of 50-300 Pa for 5 hours. Then, 1.15 mol of 1,3-propanesulfonyl lactone (1,3-PS) was added dropwise under a negative pressure of 150 Pa to 400 Pa, and the reaction was maintained at 90 to 120 °C for 25 hours. The mixture was then cooled to room temperature (25 °C) and extracted five times with ethylene glycol ether (3 times the volume of the product) to remove small molecule salts. The solvent was then recovered by vacuum distillation to obtain β-naphthoylsulfonylimide polyoxypropylene / ethylene ether propanesulfonate potassium salt-3+14. Finally, water was added and stirred until homogeneous, adjusting the solid content to 80%, which was designated as additive F.

[0067] The structural formula of additive F is shown below: Additive F (β-naphthoylsulfonylimide polyoxypropylene / ethylene ether propane sulfonate potassium salt-3+14) A cyanide-free alkaline silver plating solution was prepared using additive F.

[0068] The preparation method of the cyanide-free alkaline silver plating solution for advanced packaging is the same as in Example 1.

[0069] Performance testing: 1. The adhesion of the silver plating layer in Examples 1-6 was tested. The specific method is as follows: The adhesion of electroplated silver coatings was tested using the white grid method. First, the electroplated test piece (such as...) was placed... Figure 5 As shown in (a), the sample is placed flat on a lab table covered with a lint-free cloth. Using a white grid cutter, cut along the coating 1 cm from the edge of the coating at a speed of 20-50 mm / s. Then rotate the sample 90° and repeat the above operation on the cut lines to form a grid pattern (as shown in [image]). Figure 5 (As shown in (b)). Gently blow along the two diagonals of the grid pattern five times each to remove any remaining debris. Next, apply 3M translucent tape to the entire grid and peel it off at a speed of 20-50 mm / s at a 45° angle (as shown in (b)). Figure 5 (As shown in (c)). Observe the coating peeling of the test specimen. If there is no coating peeling and no coating residue on the corresponding contact surface of the 3M adhesive, it indicates that the silver coating has good adhesion to the substrate, and the internal stress is small or non-existent, and it is judged as qualified; if the coating peels off to varying degrees and there is coating residue on the corresponding contact surface of the 3M adhesive, it indicates that the silver coating has poor adhesion to the substrate, and the internal stress is large, and it is judged as unqualified. (As shown in Table 1 below) Table 1: Summary of Test Results for Coated White Crossblade

[0070] Note: The failure test results of the white grid knife are not limited to the three effect diagrams listed above, but also include all coating defects of different degrees.

[0071] Table 2. Test results and conclusions of coating adhesion in Examples 1-6

[0072] 2. Surface roughness test of electroplated silver coating, the specific method is as follows: The Spanish Senofar Sneox 3D optical profilometer was used to analyze the microscopic roughness of a silver coating under a 50X magnification interferometer lens. ISO 25178, Surface Properties (Surface Roughness Measurement), is an international standard specifying methods for evaluating surface roughness. Sa represents the arithmetic mean height of the micro-profile within the selected range (10 μm × 10 μm).

[0073] Table 3. Results and conclusions of silver coating roughness tests in Examples 1-6

[0074] All the raw materials listed in this invention, as well as the upper and lower limits and ranges of the raw materials and the upper and lower limits and ranges of the process parameters (such as temperature, time, etc.), can realize this invention. Examples are not listed one by one here.

[0075] The above description is merely a preferred embodiment of the present invention, and should not be construed as limiting the scope of the invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications are also considered to be within the scope of protection of the present invention.

Claims

1. A cyanide-free alkaline silver plating additive for advanced packaging, characterized in that, The additive is a mixture of aqueous solutions of o-benzoylsulfonylimide polyoxypropylene / ethylene ether propane sulfonate and / or β-naphthoylsulfonylimide polyoxypropylene / ethylene ether propane sulfonate; The general structural formulas of o-benzoylsulfonylimide polyoxypropylene / ethylene ether propane sulfonate or β-naphthoylsulfonylimide polyoxypropylene / ethylene ether propane sulfonate are as follows: and , As mentioned above, a=c=0~3, b=d=3~20, and R is any one of K and Na.

2. The cyanide-free alkaline silver plating additive according to claim 1, characterized in that, The additive is selected from potassium salt of o-benzoyl sulfonylimide polyoxypropylene / ethylene ether propane sulfonate. Sodium sodium benzoyl sulfonyl imide polyoxypropylene / ethylene ether propane sulfonate, potassium salt of o-benzoylsulfonylimide polyoxyethylene ether propane sulfonate Sodium sodium benzoyl sulfonyl imide polyoxyethylene ether propane sulfonate β-Naphthoylsulfonylimide polyoxypropylene / ethylene ether propane sulfonate potassium salt, β-Naphthoylsulfonylimide polyoxypropylene / ethylene ether propane sulfonate sodium salt β-Naphthylsulfonylimide polyoxyethylene ether propane sulfonate potassium salt, Sodium β-naphthylsulfonylimide polyoxyethylene ether propane sulfonate A mixture of one or two aqueous solutions.

3. A method for preparing a cyanide-free alkaline silver plating additive, characterized in that, Includes the following steps: Step 1: Solid o-benzoylsulfonylimide or β-naphthoylsulfonylimide are respectively added to a high-pressure reactor, purged with nitrogen, heated and stirred to melt, dehydrated under negative pressure, and then added to propylene oxide and ethylene oxide respectively under nitrogen protection to obtain o-benzoylsulfonylimide polyoxypropylene / ethylene ether or β-naphthoylsulfonylimide polyoxypropylene / ethylene ether. Step 2: Transfer the o-benzoylsulfonylimide polyoxypropylene / ethylene ether or β-naphthoylsulfonylimide polyoxypropylene / ethylene ether obtained in Step 1 into an atmospheric pressure reactor, add an alkaline catalyst, and react at a certain temperature. After the reaction is completed, add 1,3-propane sulfonyl lactone dropwise under a closed negative pressure state and stir the reaction to obtain o-benzoylsulfonylimide polyoxypropylene / ethylene ether sulfonate or β-naphthoylsulfonylimide polyoxypropylene / ethylene ether sulfonate. Step 3: The o-benzoylsulfonylimide polyoxypropylene / ethylene ether sulfonate or β-naphthoylsulfonylimide polyoxypropylene / ethylene ether sulfonate obtained in Step 2 are subjected to solvent extraction, distillation to remove salt, and vacuum distillation to remove solvent, respectively. The product obtained after distillation is adjusted with water to obtain cyanide-free alkaline electroplating silver additive. The o-benzoylsulfonylimide polyoxypropylene / ethylene ether sulfonate obtained after desalting is designated as cyanide-free alkaline electroplating silver additive (I); the β-naphthoylsulfonylimide polyoxypropylene / ethylene ether sulfonate obtained after desalting is designated as cyanide-free alkaline electroplating silver additive (II).

4. The method for preparing the cyanide-free alkaline silver plating additive according to claim 3, characterized in that, Cyanide-free alkaline silver plating additive (I) and cyanide-free alkaline silver plating additive (II) are mixed to obtain cyanide-free alkaline silver plating additive (III). The mass ratio of cyanide-free alkaline silver plating additive (I) to cyanide-free alkaline silver plating additive (II) is 1:0.25~3.

35.

5. The method for preparing the cyanide-free alkaline silver plating additive according to claim 3, characterized in that, In step one, the heating and stirring temperature range is 115~145℃, and the negative pressure dehydration conditions are 120~145℃ and negative pressure range of 20~500Pa for 3~5 hours until the moisture content is less than 0.01%.

6. The method for preparing the cyanide-free alkaline silver plating additive according to claim 3, characterized in that, In step one, the mass ratio of o-benzoylsulfonylimide and / or β-naphthoylsulfonylimide, propylene oxide, and ethylene oxide is 1:0~1.0:0.5~5.0, the addition polymerization reaction pressure is 0.2~0.6MPa, the reaction temperature is 125~225℃, and the stirring and heat preservation reaction time is 10~24 hours.

7. The method for preparing the cyanide-free alkaline silver plating additive according to claim 3, characterized in that, In step two, the alkaline catalyst includes any one or two of potassium hydroxide, sodium hydroxide, potassium methoxide, sodium methoxide, potassium tert-butoxide, and sodium tert-butoxide; the mass fraction of the alkaline catalyst is 0.01~0.04%, the reaction is carried out under negative pressure of 50~550Pa, at 65~85℃, for 2~6 hours.

8. The method for preparing the cyanide-free alkaline silver plating additive according to claim 3, characterized in that, In step two, the mass ratio of o-benzoylsulfonylimide polyoxypropylene / ethylene ether or β-naphthoylsulfonylimide polyoxypropylene / ethylene ether to 1,3-propanesulfonyl lactone is 1:0.1~0.

45. 1,3-propanesulfonyl lactone is added dropwise while maintaining a closed negative pressure state. The reaction is carried out at 90~135℃ under pressure for 5~25 hours, with the negative pressure range being 100~500Pa throughout.

9. The method for preparing the cyanide-free alkaline silver plating additive according to claim 3, characterized in that, In step three, the solvent used for solvent extraction is selected from any one of ethylene glycol ether, light aromatic hydrocarbon solvent oil, N,N-dimethylacetamide, etc.; the amount of solvent used is 2 to 4 times the volume of o-benzoylsulfonylimide polyoxypropylene / ethylene ether sulfonate or β-naphthoylsulfonylimide polyoxypropylene / ethylene ether sulfonate, and the extraction is performed 3 to 5 times.

10. A silver plating solution for advanced packaging, characterized in that, It includes the cyanide-free alkaline electroplating silver additive according to any one of claims 1-2, or the cyanide-free alkaline electroplating silver additive prepared by the method according to any one of claims 3-9.

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