Nickel in electroless nickel solutions by thermometric EDTA titration

Importance of the Topic

Precise control of nickel concentration in electroless plating baths is essential for achieving uniform deposit thickness, optimal corrosion resistance and mechanical properties. Reliable analytical methods support quality assurance in industrial plating processes.

Objectives and Study Overview

The aim is to develop and validate a fully automated thermometric EDTA titration for nickel determination in electroless plating solutions. The approach combines a controlled excess of EDTA with back-titration using copper sulfate, enabling fast and reproducible measurements.

Methodology

An aliquot containing approximately 2.5 mmol of nickel is diluted to 30 mL with deionized water. A known excess of 1.0 M Na4EDTA and an ammonia/ammonium chloride buffer are pre-dosed. The residual EDTA is back-titrated with 1.0 M CuSO4 to a single thermometric endpoint. Key parameters include a titrant delivery rate of 4 mL/min, a delay before start of 5 seconds and data smoothing factor of 62.

Used Instrumentation

• Thermometric titrator equipped with a temperature sensor for endpoint detection
• 814 Sample Processor for automated sample dosing and reagent addition
• Magnetic stirring assembly ensuring consistent agitation

Main Results and Discussion

Electroless nickel plating solutions submitted by customers yielded nickel contents of 5.40 ± 0.024% w/v and 2.76 ± 0.025% w/v (n = 8). The method exhibited high precision and linear response across the working range. Standardization of the CuSO4 titrant via linear regression against EDTA standards confirmed accuracy.

Benefits and Practical Applications

The fully automated workflow minimizes operator intervention, reduces analysis time, and enhances reproducibility. It is ideal for routine quality control in plating facilities and research laboratories monitoring bath composition.

Future Trends and Potential Applications

Integration with laboratory information management systems (LIMS), real-time bath monitoring and extension to other metal systems are promising developments. Advances in sensor miniaturization and eco-friendly reagent formulations may further improve sustainability and enable on-line process control.

Conclusion

Thermometric EDTA back-titration provides a robust, precise and automated approach for nickel analysis in electroless plating baths, supporting consistent coating performance and streamlined QA/QC operations.

Reference

• Thermo Fisher Scientific. Thermometric Titration Application Note No. H-090. Nickel in electroless nickel solutions by thermometric EDTA titration.