Suppressor «MACuSpec TM PPR 100 Wetter» in acid copper baths (MacDermid)

Significance of the topic

The accurate determination of organic suppressors such as MACuSpec™ PPR 100 Wetter in acid copper electroplating baths is critical for ensuring consistent deposit quality, bath stability and process efficiency. Reliable monitoring of suppressor concentration supports optimal throw power, minimizes defects and helps maintain plating performance in high-throughput industrial environments.

Study objectives and overview

This Application Note describes a combined dilution titration (DT) and cyclic voltammetric stripping (CVS) approach to quantify MACuSpec™ PPR 100 Wetter in acid copper baths. The goal is to establish a simple, accurate electroanalytical protocol compatible with standard bath compositions and routine quality control workflows.

Methodology

Sample Preparation:

• Collect plating bath aliquot.
• Perform a 1 : 10 dilution with the virgin make-up solution (VMS) containing CuSO₄, H₂SO₄ and HCl at supplier-specified concentrations.

CVS-Based Titration:

• Use a rotating disk electrode (RDE) hydrodynamic setup at 2 000 rpm.
• Scan potential from +1.575 V to –0.175 V and back at 0.1 V/s with 6 mV steps.
• Detect copper stripping peak near +0.25 V, using the charge ratio Q/Q₀ = 0.5 for endpoint evaluation.

Instrumentation

• Working Electrode: Platinum rotating disk electrode with interchangeable Pt tip (Drive shaft code 6.1246.000; CVS tip code 6.1204.160).
• Auxiliary Electrode: Platinum wire (code 6.0343.000).
• Reference Electrode: Ag/AgCl in 3 M KCl with H₂SO₄ (1 M) intermediate electrolyte (code 6.0728.020; intermediate code 6.1245.010).
• Stirring and control via standard potentiostat/galvanostat compatible with RDE mode.

Main results and discussion

The titration curve demonstrates a clear linear relationship between added suppressor volume and the normalized stripping charge (Q/Q₀). The plotted cyclic voltammograms reveal well-defined copper stripping peaks, and the calibration delivers reproducible endpoints with ±0.25 V window. Sensitivity and precision meet industrial QC requirements for suppressor levels typical in acid copper baths.

Benefits and practical applications of the method

• Rapid, on-site determination of suppressor concentration without complex sample workup.
• High repeatability and clear electrochemical endpoint detection.
• Minimal reagent consumption, leveraging existing bath make-up solutions.
• Easy integration into routine bath analysis protocols for laboratories and plating shops.

Future trends and opportunities

Advances could include full automation of the DT-CVS workflow, miniaturized or flow-through electrochemical cells for inline monitoring, and coupling with digital process control systems. Exploring alternative electrode materials or advanced signal processing may further enhance sensitivity and reduce analysis time.

Conclusion

The described DT-CVS method provides a straightforward, accurate and cost-effective tool for quantifying MACuSpec™ PPR 100 Wetter in acid copper plating baths. Its robust performance and ease of use make it suitable for routine quality control, enabling tighter process control and improved deposit uniformity.

References

• MacDermid. Application Note No. V-141, Version 1.0.