Measurement of TOC in Electroplating Solution Using TOC-V WS

Importance of the Topic

Organic additives are essential in copper and nickel electroplating solutions to achieve uniform deposit thickness and high surface quality in printed circuit board production. Precise monitoring of these low‐level additives prevents defects and supports consistent manufacturing output. Total organic carbon analysis offers a direct and sensitive approach to quantify organic species in plating baths.

Study Objectives and Overview

This study evaluates the use of a wet oxidation TOC analyzer for direct measurement of total organic carbon in copper plating solutions. Key goals include establishing calibration procedures for total carbon and inorganic carbon fractions, assessing the need for sample pretreatment, and validating method accuracy through spike recovery experiments.

Methodology

The procedure involved:

• Preparation of calibration standards for total carbon (TC) using potassium hydrogen phthalate at 0 and 2 mgC/L
• Preparation of inorganic carbon (IC) standards using sodium carbonate and sodium hydrogen carbonate at 0 and 1 mgC/L
• Measurement of undiluted copper plating solutions containing approximately 13% copper sulfate without additional pretreatment
• Calculation of TOC by subtracting IC from TC

Instrumentation

The analysis was conducted using a Shimadzu Wet Oxidation TOC Analyzer TOC‐VWS configured for sequential measurement of TC and IC.

Key Results and Discussion

Two commercially relevant copper plating solutions (A and B) were analyzed. Calibration curves demonstrated good linearity through the origin for both TC and IC. Measured values were:

• Solution A: TC 0.443 mgC/L, IC 0.152 mgC/L, resulting TOC 0.291 mgC/L
• Solution B: TC 0.375 mgC/L, IC 0.123 mgC/L, resulting TOC 0.252 mgC/L

Spike recovery tests were performed by adding 1 mgC/L of potassium hydrogen phthalate. Recovery rates approached 100% (98.8% for A and 101% for B), confirming negligible matrix interference from copper sulfate.

Benefits and Practical Applications

Direct TOC measurement without dilution simplifies sample handling and reduces error potentials. The method reliably detects low‐level organic additives, enabling tighter process control and rapid quality assurance in PCB plating operations.

Future Trends and Potential Applications

Advances may include integration of inline TOC monitoring for real‐time process feedback, expansion to other metal plating systems, coupling with chemometric data analysis for predictive maintenance, and development of compact analyzers for on‐site quality checks.

Conclusion

Wet oxidation TOC analysis using the Shimadzu TOC‐VWS provides an effective, accurate, and straightforward approach to quantify organic additives in copper plating baths. High recovery rates and elimination of dilution steps support its adoption for routine quality control in electroplating processes.

Reference

• Shimadzu Application News No O31 Measurement of TOC in Electroplating Solution Using TOC‐VWS