Brightener «Copper GleamTM 2001 Additive» in acid copper baths (Rohm and Haas Electronic Materials)

Importance of the Topic

Organic brighteners such as Copper GleamTM 2001 play a critical role in acid copper electroplating by controlling deposit brightness, leveling, and overall surface quality. Reliable quantification of these additives is essential for process optimization, quality control, and product consistency.

Objectives and Study Overview

This application note describes the development and validation of a rapid, sensitive method for determining Copper GleamTM 2001 additive in acid copper plating baths. The approach combines cyclic voltammetric stripping (CVS) with a modified linear approximation technique (MLAT) for calibration, enabling direct analysis without extensive sample preparation.

Methodology

The analytical procedure involves direct mixing of plating bath samples with a carrier suppressor, followed by voltammetric measurement under hydrodynamic conditions. Key steps:

• Intercept solution: 30 mL virgin make-up bath spiked with 1.2 mL carrier.
• Sample measurement: 10 mL plating bath mixed with 0.2 mL carrier.
• No additional sample preparation needed.
• Calibration via MLAT to correct baseline and enhance linearity.

Instrumentation Used

The analysis employs a rotating disk electrode (RDE) system with the following components:

• Working electrode: platinum RDE with Pt tip for CVS.
• Auxiliary electrode: platinum wire.
• Reference electrode: Ag/AgCl in 3 M KCl, with KNO3 intermediate electrolyte.
• Rotation speed: 2000 rpm.
• CVS parameters: start potential 1.575 V, vertex potentials –0.3 V and 1.575 V, step 0.006 V, sweep rate 0.15 V/s.

Main Results and Discussion

The voltammograms exhibit a distinct copper stripping peak around 0.2 V (±0.2 V). Plotting the charge difference (Q–Q') against brightener concentration yields a linear response from 0 to 0.8 mL/L. The method demonstrates good reproducibility, sensitivity and a detection limit suitable for routine bath monitoring.

Benefits and Practical Applications

This CVS–MLAT approach offers:

• Rapid, direct analysis without sample pretreatment.
• High sensitivity for low concentrations of brightener.
• Simple calibration and data evaluation.
• Compatibility with industrial process control and QA/QC routines.

Future Trends and Opportunities

Advances may include miniaturized in-line sensors, integration with automated process monitoring, and adaptation to other electroplating additives. Emerging data analytics and process control software could further enhance real-time bath management.

Conclusion

The cyclic voltammetric stripping method combined with MLAT calibration provides a robust, efficient means to quantify Copper GleamTM 2001 brightener in acid copper baths, supporting precise control of electroplating processes.