Suppressor «Thru-Cup EVF-B» in acid copper baths (Uyemura)

Importance of the Topic

Additives in acid copper baths such as suppressors are critical for controlling deposit morphology and quality in electroplating processes. Accurate determination of these organic polymers ensures bath stability, consistent deposition and reduced defects in copper coatings.

Objectives and Study Overview

This application note describes a method for the quantitative determination of the suppressor Thru Cup EVF-B directly in acid copper electroplating baths. The approach combines dilution titration with cyclic voltammetric stripping to establish a calibration curve and enables rapid analysis without extensive sample preparation.

Methodology and Instrumentation

• Sample: acid copper electroplating bath with CuSO4, H2SO4 and NaCl at supplier specified concentrations
• Measuring solution: 50 mL of virgin make up solution
• Cell configuration:
  • Working electrode: platinum rotating disk electrode at 2000 rpm
  • Auxiliary electrode: platinum wire
  • Reference electrode: Ag/AgCl in 3 mol/L KCl with saturated KNO3 intermediate electrolyte
• Analysis mode: cyclic voltammetric stripping
• Calibration technique: dilution titration
• Measurement parameters: start potential 1.575 V, vertex potentials -0.25 V and 1.575 V, step 0.006 V, scan rate 0.1 V/s
• Evaluation: copper stripping peak potential at 0.2 V and charge ratio Q over Q0 of 0.6

Used Instrumentation

• Drive shaft for RDE, part number 6.1246.000
• Platinum tip for voltammetric stripping, part number 6.1204.160
• Auxiliary platinum electrode, part number 6.0343.000
• Ag/AgCl reference electrode system, part number 6.0728.020
• Intermediate electrolyte container, part number 6.1245.010

Key Results and Discussion

The addition of Thru Cup EVF-B to the plating bath resulted in a proportional decrease in the copper stripping charge, reflected by the Q/Q0 ratio. The calibration curve obtained via dilution titration exhibited a linear relationship between suppressor concentration and the evaluated charge ratio. Graphical data illustrated a clear suppression effect corresponding to incremental inhibitor volumes, enabling precise quantification.

Benefits and Practical Applications of the Method

• Direct analysis in plating baths without complex pretreatment
• High reproducibility and a linear calibration range
• Rapid turnaround suitable for routine quality control
• Enhanced control over coating properties in industrial electroplating

Future Trends and Potential Applications

Advancements in electrode materials and automation are expected to further improve sensitivity and throughput. Integration with inline monitoring and data analytics may enable real time process control and predictive maintenance in manufacturing environments.

Conclusion

The described cyclic voltammetric stripping method combined with dilution titration offers a reliable and efficient tool for monitoring Thru Cup EVF-B in acid copper baths. Its simplicity and accuracy support rigorous quality assurance in electroplating applications.

References

Application Note V-155 Version 1.0 Uyemura