Online analysis of organic additives in copper plating process

Significance of the Topic

High‐precision copper deposition is essential for meeting the miniaturization and reliability demands in modern PCB production. Organic additives such as suppressors, brighteners, and levelers regulate deposit morphology and feature filling, directly impacting board performance and yield. Continuous monitoring of these additives within tight concentration windows ensures consistent plating quality and reduces defect rates.

Objectives and Study Overview

This application note describes an online analysis strategy for real‐time monitoring of organic additives in copper electroplating baths. By integrating a Metrohm 2060 CVS Process Analyzer into the plating line, the study aims to maintain optimal additive levels, improve process stability, and demonstrate reduced manual sampling compared with traditional laboratory‐based cyclic voltammetric stripping (CVS) methods.

Methodology

The core technique employs cyclic voltammetric stripping directly in the process stream. A three‐electrode electrochemical cell with a rotating platinum disk electrode replicates copper deposition and stripping under actual plating conditions. The analyzer applies a defined voltage waveform to the working electrode and records the resulting current. Variations in the stripping peak correlate with suppressor, brightener, and leveler concentrations, allowing calculation of their effective levels. Automated sample conditioning and measurement cycles run continuously, enabling detection of rapid fluctuations and reducing human error.

Used Instrumentation

• 2060 CVS Process Analyzer: inline voltammetric analyzer for organic additive quantification in copper baths
• 2060 TI Process Analyzer: complementary titration and photometric system for copper, sulfate, and chloride determination

Main Results and Discussion

Implementation of online CVS enabled uninterrupted tracking of additive concentrations, revealing transient deviations that manual sampling would miss. Automation improved repeatability and eliminated safety risks associated with manual handling of corrosive samples. Integration with process control systems allowed real‐time alarms and corrective dosing, stabilizing bath composition and enhancing plating consistency.

Benefits and Practical Applications

• Cost savings: optimized additive consumption and reduced waste
• Improved quality: proactive detection of concentration drifts prevents defects
• Labor efficiency: minimizes reliance on manual laboratory analyses
• Safety: contained automation reduces operator exposure to hazardous chemicals

Future Trends and Applications

Advances may include integration with Industry 4.0 platforms for data analytics and predictive maintenance, development of compact sensor modules for distributed monitoring, and machine learning algorithms to optimize dosing strategies. Broader adoption across semiconductor and specialty plating processes is expected as inline electrochemical analysis matures.

Conclusion

Online cyclic voltammetric stripping with the 2060 CVS Process Analyzer delivers continuous, accurate monitoring of organic additives in copper plating baths. This approach enhances process control, improves product quality, reduces labor requirements, and supports proactive maintenance in high‐volume PCB manufacturing.

References

1. Eurocircuits (2022). The influence of copper distribution on PCB quality.
2. Yen M‐Y, Chiang M‐H, Tai H‐H et al. Next generation electroplating technology for high planarity, minimum surface deposition microvia filling. In: 7th International Microsystems, Packaging, Assembly and Circuits Technology Conference (IMPACT); 2012. pp 259–262.