Suppressor «MultiBondTM 100 Part A20» in an acid copper bath (MacDermid)

Significance of Topic

The control of organic suppressors in acid copper electroplating baths is critical for achieving uniform deposit thickness, minimizing defects and ensuring high-quality surface finishes. MultiBondTM 100 Part A20 is a commonly used suppressor whose precise concentration must be monitored to maintain plating performance and bath stability.

Study Objective and Overview

This work presents a quantitative approach for determining MultiBondTM 100 Part A20 in an acid copper bath using dilution titration combined with cyclic voltammetric stripping. The method aims to provide rapid, accurate and reproducible measurements suitable for routine bath analysis and process control.

Methodology and Instrumentation

Sample Preparation

• An aliquot of the acid copper plating bath is diluted tenfold with a virgin make-up solution (VMS) containing CuSO4, H2SO4 and NaCl at supplier-specified concentrations.

Analytical Technique

• Dilution titration (DT) using cyclic voltammetric stripping (CVS) on a rotating disc electrode (RDE).
• Calibration is based on the change in stripping charge ratio Q/Q0 following incremental additions of suppressor standard.

Instrumental Setup

• Working Electrode: Platinum rotating disc electrode (Pt-RDE) with Pt tip.
• Auxiliary Electrode: Platinum wire.
• Reference Electrode: Ag/AgCl in 3 mol L-1 KCl with saturated KNO3 intermediate electrolyte.
• Hydrodynamic Conditions: 2000 rpm stirring.
• CVS Parameters: potential window from +1.575 V to –0.25 V and back, step 0.006 V, sweep rate 0.1 V s-1, evaluating peak at approx. 0.2 V ± 0.2 V.

Results and Discussion

Cyclic voltammograms recorded after each titrant addition show systematic changes in the copper stripping peak current corresponding to suppressor concentration. Plotting the ratio Q/Q0 against titrant volume yields a linear calibration curve, enabling determination of suppressor levels in the bath sample with high precision. The method demonstrates good reproducibility and a well-defined detection range appropriate for industrial plating baths.

Practical Benefits and Applications

• Minimal sample preparation with simple dilution step.
• Rapid analysis cycle compatible with routine QA/QC workflows.
• Hydrodynamic control ensures reproducible mass transport and signal stability.
• Applicable to on-site monitoring of bath additives in electroplating facilities.

Future Trends and Opportunities

Advances in miniaturized electrochemical sensors and automated titration systems are expected to further streamline suppressor monitoring. Integration with digital control platforms could enable real-time bath adjustment. The approach may be extended to other organic additives and metal plating systems by adapting electrode materials and potential programs.

Conclusion

The described method offers a robust and straightforward protocol for quantifying MultiBondTM 100 Part A20 in acid copper plating baths. Its combination of dilution titration and cyclic voltammetric stripping provides accurate results, supporting effective process control in electroplating operations.