Method for spectrophotometric quantitative analysis of polyethylene glycol in acidic copper plating solution based on phosphotungstate-polyethylene glycol composite colloid

Abstract

This invention relates to the analysis and detection of additives in acid copper electrodeposition solutions, specifically to the analysis and detection of PEG, an additive used in the production of electrolytic copper foil and in the electroplating copper interconnect process for chips and printed circuit boards. The method involves: under acidic conditions, protonated, positively charged PEG electrostatically binds with phosphotungstenate ions to form a macromolecular colloidal complex, phosphotungstenate-PEG. This colloidal complex exhibits sensitive absorption at 300 nm. The absorbance of the phosphotungstenate-PEG colloid is measured spectrophotometrically, and the absorbance value shows a linear relationship with the PEG concentration in the acidic copper solution. This invention enables rapid and accurate quantitative analysis of the additive PEG in copper electrodeposition solutions, greatly aiding in the effective monitoring and management of acid copper electrodeposition solutions and stabilizing the quality of electrolytic copper foil and the copper plating layer.

Description

Technical Field

[0001] This invention relates to the field of additive analysis and detection technology in acid copper electrodeposition solutions, and in particular to a spectrophotometric quantitative analysis method for polyethylene glycol in acidic copper plating solutions based on phosphotungstate-polyethylene glycol composite colloids. Background Technology

[0002] Acidic copper electrodeposition solutions generally refer to copper sulfate plating solutions, which can be used in many fields, such as the manufacture of electrolytic copper foil and the electroplating of copper interconnects for chips and printed circuit boards. Different companies use vastly different additive compositions based on their equipment and process technology. However, polyethylene glycol (PEG) is commonly found in acidic copper electrodeposition solutions across various companies, highlighting the importance of PEG analysis in copper electrodeposition solutions. In actual acidic copper electrodeposition solutions, multiple additives are usually present simultaneously, such as sodium polydithiopropane sulfonate (SPS) and 2-mercaptothiazoline (MTZ). These coexisting substances severely interfere with the selective determination of PEG. Therefore, for highly selective and accurate quantitative analysis of PEG, the management of the electrodeposition solution is even more crucial.

[0003] Since PEG is a common surfactant, its analysis is commonly performed in aqueous phases, such as by liquid chromatography, gel permeation chromatography, spectrophotometry, and oscillometric polarography. With the increasing application of PEG in electroplating technology, PEG analysis in electrodeposition solutions has been frequently reported. A literature report (Yang Zhiye, Determination of PEG 6000 content in HEDP copper plating solution, Materials Protection, 2023(56), 181-183) discusses spectrophotometric analysis of PEG in copper plating solutions. However, this method is only applicable when only one PEG additive is used. Currently, acidic copper electrodeposition solutions typically contain two or more additives besides PEG. This presents a significant challenge to the selective determination of PEG.

[0004] Therefore, developing a method for highly selective, rapid, and accurate quantitative analysis of PEG from complex additive systems has become a pressing technical problem to be solved in the field of acidic copper electrodeposition process control. Summary of the Invention

[0005] The technical problem this invention aims to solve is to overcome the shortcomings of existing technologies and provide a spectrophotometric quantitative analysis method for polyethylene glycol (PEG) in acidic copper plating solutions based on phosphotungstic acid-polyethylene glycol (PEG) composite colloids. This invention focuses on the selective analysis and detection of PEG among numerous additives in acid copper electrodeposition solutions, enabling effective management of the acid copper electrodeposition process.

[0006] The technical solution adopted by this invention to solve its technical problem is: A spectrophotometric quantitative analysis method for polyethylene glycol (PEG) in acidic copper plating solutions based on phosphotungstic acid-PEG composite colloids is disclosed. Under acidic conditions of pH 1.5–2.5, PEG in the sample is contacted with phosphotungstic acid to form a phosphotungstic acid-PEG colloidal complex. The colloidal complex exhibits maximum absorption at a wavelength of 300 nm using spectrophotometry. The concentration of PEG in the sample is calculated based on a standard curve and linear regression equation established for the relationship between absorbance and PEG concentration.

[0007] In acidic copper electrodeposition solutions, PEG can be used as an electrodeposition additive primarily because, under acidic conditions, the ether oxygen bond (-O-) of PEG is protonated, forming a positively charged PEG. This PEG strongly adsorbs onto the negative electrode surface, smoothing and brightening the copper electrodeposition surface. Based on this characteristic, this invention proposes utilizing the electrostatic binding of negatively charged phosphotungsten ions with protonated PEG to form a stable phosphotungsten ion-PEG macromolecular colloidal complex. Since the phosphotungsten ion-PEG colloid exhibits characteristic absorption in the near-ultraviolet region, selective quantitative analysis of PEG can be achieved by measuring its absorbance spectrophotometrically.

[0008] It is generally believed that the protonation of the ether oxygen bond (-O-) in the PEG molecule occurs under extremely strong acidic conditions. For example, when the pH value is <0, PEG will be highly protonated, exhibiting the strongest binding ability with anions. However, under such strong acidic conditions, the stability of the phosphotungsten-PEG colloid formed by the reaction of phosphotungsten and protonated PEG will be disrupted, leading to rapid colloid aggregation. Conversely, if the pH value is too high (>3), insufficient protonation of PEG may result in a reduction of effective positive charge, weakening the electrostatic binding force with phosphotungsten, leading to incomplete reaction and a significant decrease in the stability of the phosphotungsten-PEG colloid. Therefore, the suitable pH range for the formation of stable colloids between phosphotungsten and PEG is between 1.5 and 2.5. If the pH value of the reaction system deviates from this range, it can be fine-tuned using dilute sulfuric acid or a corresponding alkaline solution. The alkaline solution is the hydroxide corresponding to the phosphotungsten group; for example, sodium phosphotungsten corresponds to sodium hydroxide.

[0009] Furthermore, the phosphotungsten is selected from at least one of sodium phosphotungsten, potassium phosphotungsten, and ammonium phosphotungsten.

[0010] Furthermore, the mass ratio of the phosphotungstate to PEG is (30-100):1.

[0011] For the anions that form stable colloids with protonated PEG, alkali metal and ammonium salts of phosphotungsten can be selected, such as sodium phosphotungsten, potassium phosphotungsten, and ammonium phosphotungsten. The mass ratio of phosphotungsten to PEG is (30–100):1. If the amount of phosphotungsten is too small, it will be insufficient to form phosphotungsten-PEG colloids; conversely, if too much phosphotungsten is added, the ionic strength in the solution will increase, and a large amount of electrolyte (phosphotungsten and its dissociation products) will compress the electric double layer on the particle surface, shortening the effective distance of the electrostatic repulsion force, leading to irreversible aggregation of the formed colloid. In addition, since phosphotungsten ions themselves have a certain absorption in the ultraviolet and visible light regions (usually the solution becomes slightly yellow with increasing concentration), the addition of excess phosphotungsten will significantly increase the background absorbance of the reaction system.

[0012] Furthermore, an alcohol stabilizer is added to the reaction system before the formation of the colloidal complex.

[0013] Furthermore, the alcohol stabilizer is selected from at least one of isopropanol or ethylene glycol, and its volume fraction in the reaction system is 2-5%.

[0014] To improve the dispersion stability of the colloidal complex in the aqueous phase, surfactants are added. In this invention, before forming the colloidal complex, an organic solvent such as isopropanol or ethylene glycol is added to the reaction system, which effectively improves the stability of the phosphotungstic acid-PEG colloid in the aqueous phase. The colloidal stabilization mechanism is due to the adsorption of the hydroxyl groups of isopropanol (-OH) and ethylene glycol (-OH / -OH) onto the surface of the colloidal particles via hydrogen bonds (bonding with the unsaturated PEG ether oxygen or phosphotungstic acid oxygen atoms on the particles). After adsorption, their organic carbon chains face the solution, forming a nanometer-thick physical barrier around the particles. When two particles approach each other, this adsorbed layer is compressed or overlapped, generating a strong repulsive force, thereby effectively preventing particle aggregation.

[0015] Furthermore, the spectrophotometric quantitative analysis method for polyethylene glycol in acidic copper plating solution based on phosphotungstic acid-polyethylene glycol composite colloid specifically includes the following steps: Step S1: Prepare the acid copper base solution: The components of the acid copper base solution are the same as those of the actual copper electrodeposition solution after removing the additives, and both have the same copper sulfate concentration, sulfuric acid concentration, and chloride ion concentration. Step S2: Prepare PEG standard stock solution; Step S3: Prepare phosphotungstenate solution; Step S4: Preparation of standard working solutions: Transfer equal volumes of the copper acid base solution prepared in step S1 into multiple volumetric flasks, then add different volumes of the PEG standard stock solution prepared in step S2 to each flask, followed by the addition of alcohol stabilizer and the phosphotungsten solution prepared in step S3. Dilute to volume with water to prepare a set of standard working solutions with gradient PEG concentrations; the pH value of the standard working solutions is 1.5–2.5. Step S5: Plotting the PEG standard curve: After a stable phosphotungstate-PEG colloidal complex is formed in the standard working solution, the absorbance of a set of standard working solutions prepared in step S4 is measured at a wavelength of 300 nm using a UV-Vis spectrophotometer. The standard curve and linear regression equation are established with PEG concentration as the abscissa and absorbance value as the ordinate. Step S6: Measure the actual sample: Take the copper electrodeposition solution to be tested, add alcohol stabilizer and phosphotungsten solution in the same order as in step S4, dilute with water, and measure its absorbance at 300 nm wavelength using a UV-Vis spectrophotometer. Step S7: Substitute the absorbance value measured in step S6 into the linear regression equation in step S5 to calculate the concentration of PEG in the sample to be tested.

[0016] Further, in step S2, the concentration of the PEG standard stock solution is 1000 μg / mL. The PEG standard stock solution is prepared as follows: weigh 0.1000 g of PEG and dissolve it in deionized water in a 100 mL volumetric flask to obtain a PEG concentration of 1000 μg / mL. The molecular weight of the PEG is the same as that of the PEG in the sample to be tested.

[0017] Further, in steps S4 and S6, the concentration of the phosphotungstenate solution is 2% (w / v), and the amount of phosphotungstenate added is 1-2.5 mL per 50 mL final volume. The phosphotungstenate solution is prepared by weighing 1.0 g of phosphotungstenate and diluting it with deionized water to a 50 mL volumetric flask.

[0018] Furthermore, in steps S4 and S6, the alcohol stabilizer is selected from at least one of isopropanol or ethylene glycol, and the amount of alcohol stabilizer added is 1 to 2.5 mL per 50 mL final volume.

[0019] Furthermore, in step S5, after the phosphotungstic acid-PEG colloidal complex is formed, the absorbance is measured within 1 hour to ensure the stability of the measurement results.

[0020] Furthermore, the spectrophotometric quantitative analysis method for polyethylene glycol in acidic copper plating solution based on phosphotungstate-polyethylene glycol composite colloid has a linear detection range of 1.0–10 μg / mL and a limit of detection of 0.71 μg / mL for PEG.

[0021] When interfering substances such as 2-mercaptothiazoline are present in the sample to be tested, other characteristic wavelengths in the wavelength range of 300-350nm can be selected for measurement, such as 325nm, to avoid interference.

[0022] The beneficial effects of this invention are that it is rationally designed and has the following advantages: 1. High selectivity: Based on the protonation characteristics of PEG under acidic conditions, this invention utilizes the specific electrostatic binding of phosphotungstate ions with protonated PEG to achieve selective detection of PEG. Experiments show that coexisting additives such as SPS and MTZ do not significantly interfere with the determination of PEG. Even if MTZ has some interference, it can be effectively avoided by adjusting the detection wavelength. 2. Simple and fast operation: The method of this invention does not require complicated sample pretreatment, separation or enrichment steps. The plating solution is directly diluted and reacted with phosphotungsten to determine the sample. The entire analysis process can be completed within 30 minutes, which is particularly suitable for real-time process monitoring in the production site. 3. High sensitivity and wide linear range: The detection linear range of the method of this invention is 1.0 to 10 μg / mL, and the lowest detection limit is 0.71 μg / mL, which fully meets the detection requirements of PEG concentration in actual plating solutions (usually 50 to 200 μg / mL, which falls into the linear range after dilution). 4. Good stability: By introducing an alcohol stabilizer, the dispersion stability of phosphotungstic acid-PEG colloid in the aqueous phase is significantly improved. The absorbance change rate within 30 minutes is less than 2%, ensuring the accuracy and reproducibility of the measurement results, with a relative standard deviation (RSD) of less than 3%. 5. High versatility: This invention is applicable to PEGs of different molecular weights (such as PEG400, PEG6000, PEG20000, etc.). Only PEGs with the same molecular weight as the plating solution to be tested need to be used to establish a standard curve, which has good universality. Attached Figure Description

[0023] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0024] Figure 1 The images show the UV absorption spectra (A) and standard curve (B) of the phosphotungstic acid-PEG colloidal complexes at different PEG concentrations in Example 1 of this invention. The standard curve equation is A = 0.03451C - 0.0065, R² = 0.9962.

[0025] Figure 2 The image shows the UV absorption spectrum of PEG and SPS coexisting in the copper electrodeposition solution in Example 1 of this invention, indicating that SPS does not significantly interfere with the determination of PEG.

[0026] Figure 3 The image shows the ultraviolet absorption spectrum of PEG and MTZ coexisting in the copper electrodeposition solution in Example 1 of this invention. It indicates that MTZ causes some interference at 300 nm, but this can be avoided by adjusting the detection wavelength. Detailed Implementation

[0027] The present invention will now be described in further detail with reference to the accompanying drawings. These drawings are simplified schematic diagrams, illustrating only the basic structure of the invention, and therefore only show the components relevant to the invention.

[0028] For ease of comparison and illustration, a copper electrodeposition solution similar to that used in actual production was prepared as the test sample (used in the following examples and comparative examples). Its composition was 150 g / L copper sulfate, 100 g / L sulfuric acid, and Cl... - 50 μg / mL and PEG6000 100 μg / mL. The analytical method of the present invention is described by quantitative analysis of PEG in the test sample.

[0029] In the stability test of the generated phosphotungstic acid-PEG colloid, the rate of change of absorbance value ΔA within 30 min was considered, and ΔA < 5%. When ΔA > 5%, the analytical conditions are unacceptable because the generated colloid is unstable.

[0030] In copper electrodeposition solutions, PEG is often used as an additive in addition to other additives such as sodium polydithiopropane sulfonate (SPS) and 2-mercaptothiazoline (MTZ). These additives are frequently used in combination with PEG. The amounts of SPS and MTZ added generally do not exceed 10 μg / mL. Therefore, the addition of SPS and MTZ is described in the embodiments of this invention. However, it should be noted that the scope of protection of this invention is not limited to the following embodiments.

[0031] Example 1: The spectrophotometric quantitative analysis method for polyethylene glycol in acidic copper plating solution based on phosphotungstic acid-polyethylene glycol composite colloid in this embodiment specifically includes the following steps: Step S1: Prepare copper sulfate base solution: Prepare a copper sulfate base solution with the same composition as the sample to be tested, excluding additives. Its composition is 150 g / L copper sulfate, 100 g / L sulfuric acid, and Cl... - 50 μg / mL; Step S2: Prepare PEG standard stock solution. Accurately weigh 0.1000 g of PEG6000 with the same molecular weight as the additive in the sample to be tested, and dilute to 100 mL with deionized water to prepare a PEG standard stock solution with a concentration of 1000 μg / mL. Step S3: Prepare sodium phosphotungsten solution. Prepare a 2% (w / v) sodium phosphotungsten solution: Weigh 1.0 g of sodium phosphotungsten and dilute to 50 mL in a volumetric flask with deionized water. Step S4: Preparation of standard working solutions: Transfer 1 mL of the copper acid base solution prepared in step S1 into five 50 mL volumetric flasks, add an appropriate amount of deionized water, and cool to room temperature. Then, add 1 mL of the PEG standard stock solution prepared in step S2 (1000 μg / mL) to each of the above 50 mL volumetric flasks, with volumes of 0, 0.1, 0.2, 0.3, 0.4, and 0.5 mL, respectively. Next, add 1 mL of isopropanol, an alcohol stabilizer, to each of the above volumetric flasks to bring the final concentration to 2% (v / v). Finally, add 1 mL of 2% (w / v) sodium phosphotungstenate solution and dilute to 50 mL with deionized water to obtain a set of standard working solutions with gradient PEG concentrations of 0, 2.0, 4.0, 6.0, 8.0, and 10 μg / mL. The pH value of the standard working solutions is 1.6. Step S5: Plotting the PEG standard curve: After a stable phosphotungstic acid-PEG colloidal complex has formed in the standard working solutions, the absorption spectra of the set of standard working solutions prepared in step S4 are measured using a UV-Vis spectrophotometer in the wavelength range of 250–600 nm. The results are as follows: Figure 1 As shown in A; Figure 1 It can be seen that the colloidal complex has sensitive absorption at 300 nm. The absorbance value at 300 nm was recorded, and then a standard curve was plotted with PEG concentration on the x-axis and absorbance value at 300 nm on the y-axis (e.g., ...). Figure 1 As shown in B), the linear regression equation obtained is: A = 0.03451C - 0.0065 (correlation coefficient R² = 0.9962), where A is the absorbance value and C is the PEG concentration (μg / mL). Step S6: Sample determination: Take 1 mL of the sample to be tested into a 50 mL volumetric flask, add an appropriate amount of deionized water and cool to room temperature, then add 1 mL of alcohol stabilizer, then add 1 mL of 2% sodium phosphotungsten solution, and dilute to 50 mL with deionized water. The pH value of the sample to be tested is 1.6. Use a UV-Vis spectrophotometer to measure its absorbance value at a wavelength of 300 nm. Step S7: Substitute the absorbance value measured in step S6 into the linear regression equation in step S5 to calculate the concentration of PEG in the sample to be tested. The results are listed in Table 1.

[0032] To investigate the effect of the presence of additives sodium polydithiopropane sulfonate (SPS) and 2-mercaptothiazoline (MTZ) on the determination of PEG, PEG was removed during sample preparation and replaced with 10 μg / mL SPS and 10 μg / mL MTZ, respectively, resulting in two samples. Their absorption spectra are shown below. Figure 2 and Figure 3 As shown. By Figure 2 The absorption spectrum shows that SPS concentrations close to twice the PEG concentration do not affect the analysis and determination of PEG. Figure 3 The absorption spectrum shows that MTZ has a slight effect on the analysis of PEG at 300 nm, but when the absorbance value is measured at 325 nm or later, MTZ will not affect the quantitative analysis of PEG.

[0033] To investigate the effect of the coexisting additive SPS on the determination of PEG, SPS at a concentration of 10 μg / mL was further added to the test sample containing PEG6000 100 μg / mL. Using the analytical method of this embodiment, the measured PEG result was 99.5 μg / mL, which is close to 100 μg / mL, further demonstrating the accuracy and efficiency of the determination method of the present invention. Furthermore, this result indicates that the addition of SPS does not affect the determination of PEG.

[0034] To investigate the stability of the generated phosphotungstic acid-PEG colloidal complex dispersed in aqueous solution, the rate of change of absorbance ΔA after 30 minutes was recorded, and the results are shown in Table 1.

[0035] Example 2: The rapid quantitative analysis method in this embodiment differs from that in Embodiment 1 in that steps S4 to S7 are as follows: After adding 1 mL of copper sulfate base solution and PEG standard stock solution, add 1.5 mL of ethylene glycol stabilizer, then add 2 mL of 2% potassium phosphotungstic acid solution, and finally dilute to 50 mL with deionized water. Measure the absorbance at 300 nm. The linear regression equation for absorbance value versus PEG concentration is A = 0.03518C - 0.0072 (correlation coefficient R0). 2 = 0.9976).

[0036] Take 1 mL of the sample to be tested, and perform the analysis in complete accordance with the standard curve analysis method for PEG described above. Measure the absorbance at 300 nm using a UV-Vis spectrophotometer. The concentration of PEG in the sample can be calculated using the linear regression equation for PEG obtained above, and the results are listed in Table 1.

[0037] To investigate the effect of the coexisting additive SPS on the determination of PEG, SPS at a concentration of 10 μg / mL was further added to the test sample containing PEG6000 100 μg / mL. Using the analytical method of this embodiment, the PEG concentration was measured to be 99.3 μg / mL. This result indicates that the addition of SPS does not affect the determination of PEG.

[0038] To investigate the stability of the generated phosphotungstic acid-PEG colloidal complex dispersed in aqueous solution, the rate of change of absorbance ΔA after 30 minutes was recorded, and the results are shown in Table 1.

[0039] Example 3: The rapid quantitative analysis method in this embodiment differs from that in Embodiment 1 in that steps S4 to S7 are as follows: After adding 1 mL of copper sulfate base solution and PEG standard stock solution, add 2 mL of isopropanol as a stabilizer, then add 2.5 mL of 2% ammonium phosphotungstic acid solution, and finally dilute to 50 mL with deionized water. Measure the absorbance at 300 nm. The linear regression equation for absorbance value versus PEG concentration is A = 0.03614C - 0.0081 (correlation coefficient R0). 2 = 0.9968).

[0040] Take 1 mL of the sample to be tested, and perform the analysis in complete accordance with the standard curve analysis method for PEG described above. Measure the absorbance at 300 nm using a UV-Vis spectrophotometer. The concentration of PEG in the sample can be calculated using the linear regression equation for PEG obtained above, and the results are listed in Table 1.

[0041] To investigate the effect of the coexisting additive MTZ on the determination of PEG, MTZ at a concentration of 10 μg / mL was further added to the test sample containing PEG6000 at 100 μg / mL. At this point, a wavelength of 325 nm was used for measurement, and the obtained PEG concentration was 99.5 μg / mL. This result indicates that the addition of MTZ does not affect the determination of PEG.

[0042] To investigate the stability of the generated phosphotungstic acid-PEG colloidal complex dispersed in aqueous solution, the rate of change of absorbance ΔA after 30 minutes was recorded, and the results are shown in Table 1.

[0043] Comparative Example 1: The standard curve analysis was performed as described in Example 1 above. Copper acid solution, PEG standard solution, 1 mL of isopropanol stabilizer, and sodium phosphotungstic acid solution were added. The pH of the analytical solution was adjusted to 3.0 with sodium hydroxide solution, and then diluted to 50 mL with deionized water. Absorbance analysis was performed at 300 nm using a UV-Vis spectrophotometer. The linear regression equation of absorbance values ​​on PEG concentration was obtained as A = 0.03281C - 0.0036 (correlation coefficient R0). 2 = 0.9912).

[0044] Take 1 mL of the prepared sample and perform the analysis in complete accordance with the standard curve analysis method for PEG described above. After measuring the absorbance, the concentration of PEG in the sample can be determined according to the linear regression equation of PEG obtained above. The results are listed in Table 1.

[0045] To investigate the stability of the generated phosphotungstic acid-PEG colloidal complex dispersed in aqueous solution, the rate of change of absorbance ΔA after 30 minutes was recorded, and the results are shown in Table 1.

[0046] Comparative Example 2: The analytical procedure was the same as in Example 1, except that no stabilizer was added after adding the PEG standard solution. Then, 1 mL of a 2% sodium phosphotungstenate solution was added to each PEG standard solution, and the volume was adjusted to 50 mL with deionized water. Absorbance analysis was performed at 300 nm using a UV-Vis spectrophotometer, and the linear regression equation of absorbance value on PEG concentration was obtained: A = 0.03291C - 0.0034 (correlation coefficient R). 2 = 0.9812).

[0047] Take 1 mL of the prepared sample and perform the analysis in complete accordance with the standard curve analysis method for PEG described above. After measuring the absorbance, the concentration of PEG in the sample can be determined according to the linear regression equation of PEG obtained above. The results are listed in Table 1.

[0048] To investigate the stability of the generated phosphotungstic acid-PEG colloidal complex dispersed in aqueous solution, the rate of change of absorbance ΔA after 30 minutes was recorded, and the results are shown in Table 1.

[0049] Comparative Example 3: The analytical procedure was the same as in Example 1, except that the amount of sodium phosphotungstenate solution added was increased. Specifically, after adding the copper sulfate solution and the PEG standard solution, 1 mL of isopropanol was added as a stabilizer, and then 3 mL of a 2% sodium phosphotungstenate solution was added to the aforementioned PEG standard solution. The volume was then adjusted to 50 mL with deionized water. Absorbance analysis was performed at 300 nm using a UV-Vis spectrophotometer, and the linear regression equation of absorbance value on PEG concentration was obtained: A = 0.03313C - 0.0028 (correlation coefficient R0). 2 = 0.9980).

[0050] Take 1 mL of the prepared sample and perform the analysis in complete accordance with the standard curve analysis method for PEG described above. After measuring the absorbance, the concentration of PEG in the sample can be determined according to the linear regression equation of PEG obtained above. The results are listed in Table 1.

[0051] To investigate the stability of the generated phosphotungstic acid-PEG colloidal complex dispersed in aqueous solution, the rate of change of absorbance ΔA after 30 minutes was recorded, and the results are shown in Table 1.

[0052] Table 1

[0053] Note: a. Average of three measurements taken for sample. The PEG analysis results listed in Table 1 are the average of three parallel determinations. As shown in Table 1, the standard mean deviation (RSD) of the PEG results measured in the examples is less than 3%, and the measured values ​​also have small errors compared with the actual added concentration of 100 μg / mL PEG. The examples also analyzed that the addition of SPS and MTZ does not affect the PEG analysis.

[0054] In summary, under acidic conditions, phosphotungsten ions and protonated PEG form a stable phosphotungsten-PEG colloid. This colloid exhibits sensitive absorption at 300 nm, and the measurement of this absorbance value is unaffected by other coexisting substances in the copper electrodeposition solution. This provides excellent precision and accuracy for the analysis of PEG additives in copper electrodeposition solutions. Since this invention eliminates the need for sample pretreatment for PEG determination, it significantly shortens the analysis time, making it highly suitable for process control in electrolytic copper foil production. Furthermore, the high sensitivity and selectivity of this PEG analysis and detection technology fully meet the requirements of current copper electrodeposition process control technologies.

[0055] Based on the above-described preferred embodiments of the present invention, and through the foregoing description, those skilled in the art can make various changes and modifications without departing from the inventive concept. The technical scope of this invention is not limited to the contents of the specification, but must be determined according to the scope of the claims.

Claims

1. A spectrophotometric quantitative analysis method for polyethylene glycol in acidic copper plating solution based on phosphotungstic acid-polyethylene glycol composite colloid, characterized in that: Under acidic conditions with a pH of 1.5–2.5, PEG in the test sample is brought into contact with phosphotungsten to form a phosphotungsten-PEG colloidal complex. The colloidal complex exhibits maximum absorption at a wavelength of 300 nm using spectrophotometry. The concentration of PEG in the test sample is calculated based on the established standard curve of absorbance versus PEG concentration and the linear regression equation.

2. The spectrophotometric quantitative analysis method for polyethylene glycol in acidic copper plating solution based on phosphotungstic acid-polyethylene glycol composite colloid according to claim 1, characterized in that: The phosphotungsten is selected from at least one of sodium phosphotungsten, potassium phosphotungsten, and ammonium phosphotungsten.

3. The spectrophotometric quantitative analysis method for polyethylene glycol in acidic copper plating solution based on phosphotungstic acid-polyethylene glycol composite colloid according to claim 1, characterized in that: The mass ratio of phosphotungstate to PEG is (30-100):

1.

4. The spectrophotometric quantitative analysis method for polyethylene glycol in acidic copper plating solution based on phosphotungstic acid-polyethylene glycol composite colloid according to claim 1, characterized in that: An alcohol stabilizer is added to the reaction system before the formation of the colloidal complex.

5. The spectrophotometric quantitative analysis method for polyethylene glycol in acidic copper plating solution based on phosphotungstic acid-polyethylene glycol composite colloid according to claim 4, characterized in that: The alcohol stabilizer is selected from at least one of isopropanol and ethylene glycol, and its volume fraction in the reaction system is 2-5%.

6. The spectrophotometric quantitative analysis method for polyethylene glycol in acidic copper plating solution based on phosphotungstic acid-polyethylene glycol composite colloid according to claim 1, characterized in that: Specifically, the steps include the following: Step S1: Prepare the acid copper base solution: The components of the acid copper base solution are the same as those of the actual copper electrodeposition solution after removing the additives, and both have the same copper sulfate concentration, sulfuric acid concentration, and chloride ion concentration. Step S2: Prepare PEG standard stock solution; Step S3: Prepare phosphotungstenate solution; Step S4: Preparation of standard working solutions: Transfer equal volumes of the copper acid base solution prepared in step S1 into multiple volumetric flasks, then add different volumes of the PEG standard stock solution prepared in step S2 to each flask, followed by the addition of alcohol stabilizer and the phosphotungsten solution prepared in step S3. Dilute to volume with water to prepare a set of standard working solutions with gradient PEG concentrations; the pH value of the standard working solutions is 1.5–2.

5. Step S5: Plotting the PEG standard curve: After a stable phosphotungstate-PEG colloidal complex is formed in the standard working solution, the absorbance of a set of standard working solutions prepared in step S4 is measured at a wavelength of 300 nm using a UV-Vis spectrophotometer. The standard curve and linear regression equation are established with PEG concentration as the abscissa and absorbance value as the ordinate. Step S6: Measure the actual sample: Take the copper electrodeposition solution to be tested, add alcohol stabilizer and phosphotungsten solution in the same order as in step S4, dilute with water, and measure its absorbance at 300 nm wavelength using a UV-Vis spectrophotometer. Step S7: Substitute the absorbance value measured in step S6 into the linear regression equation in step S5 to calculate the concentration of PEG in the sample to be tested.

7. The spectrophotometric quantitative analysis method for polyethylene glycol in acidic copper plating solution based on phosphotungstic acid-polyethylene glycol composite colloid according to claim 6, characterized in that: In step S2, the concentration of the PEG standard stock solution is 1000 μg / mL.

8. The spectrophotometric quantitative analysis method for polyethylene glycol in acidic copper plating solution based on phosphotungstic acid-polyethylene glycol composite colloid according to claim 6, characterized in that: In steps S4 and S6, the concentration of the phosphotungsten solution is 2% (w / v), and the amount of phosphotungsten added is 1 to 2.5 mL per 50 mL final volume.

9. The spectrophotometric quantitative analysis method for polyethylene glycol in acidic copper plating solution based on phosphotungstic acid-polyethylene glycol composite colloid according to claim 6, characterized in that: In steps S4 and S6, the alcohol stabilizer is selected from at least one of isopropanol and ethylene glycol, and the amount of alcohol stabilizer added is 1 to 2.5 mL per 50 mL final volume.

10. The spectrophotometric quantitative analysis method for polyethylene glycol in acidic copper plating solution based on phosphotungstic acid-polyethylene glycol composite colloid according to claim 1, characterized in that: The analytical method exhibits a linear detection range of 1.0–10 μg / mL for PEG, with a limit of detection of 0.71 μg / mL.

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