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

Importance of the Topic

The brightening additive in copper electroplating baths controls deposit quality, surface smoothness and appearance. Accurate monitoring of brightener concentration is critical for consistent coating performance, reduced defects and optimized operating costs in electronics, automotive and decorative industries.

Study Objectives and Overview

This application note describes a modified linear approximation technique (MLAT) combined with cyclic voltammetric stripping (CVS) to quantify MACuSpec PPR 100 brightener in acid copper baths. The aim is to establish a rapid, reagent-free protocol suited for routine quality control of plating solutions.

Methodology and Instrumentation

The method uses an intercept measurement approach. A fresh make-up solution containing CuSO4, H2SO4 and HCl serves as the supporting electrolyte. Samples from an operating bath are directly analyzed without pretreatment. A standard addition series with PPR 100 brightener diluted tenfold provides calibration.

Electrochemical parameters include:

• Working electrode: platinum rotating disk electrode (2000 rpm)
• Auxiliary electrode: platinum wire
• Reference electrode: Ag/AgCl in 3 mol/L KCl with 1 mol/L H2SO4 intermediate solution
• Scan mode: cyclic voltammetric stripping
• Calibration: modified linear approximation
• Potential window: from 1.575 V down to -0.275 V and back
• Step size: 6 mV
• Sweep rate: 0.1 V/s

Main Results and Discussion

Typical voltammograms show a copper stripping peak around 0.25 V. Plotting the charge difference (Q minus Q Intercept) against brightener concentration yields a linear relationship. The MLAT approach reduces baseline drift and improves reproducibility compared to standard CVS curves. Detection limits fall within the low microliter per liter range, adequate for industrial bath concentrations.

Benefits and Practical Applications

Using MLAT-CVS for brightener analysis offers:

• Minimal sample preparation, accelerating turnaround time
• High sensitivity and selectivity for organic brighteners in complex copper matrices
• Simple calibration via standard additions, adaptable to varying bath compositions
• Cost savings through reduced reagent consumption and faster analysis

Future Trends and Applications

Advances may include automation of the rotating disk system, integration with bath management software and expansion to multi-component additive cocktails. Coupling with in situ sensors and AI-driven calibration models could further enhance real-time monitoring and process control.

Conclusion

The MLAT method combined with cyclic voltammetric stripping provides a robust, efficient tool for determination of MACuSpec PPR 100 brightener in acid copper plating baths. Its simplicity and precision make it well suited for routine quality assurance in industrial electroplating operations.

Instrumentation Used

• Platinum rotating disk electrode assembly
• Platinum auxiliary electrode
• Ag/AgCl reference electrode with KCl saturated solution
• Electrochemical workstation capable of CVS measurements