In-line Analysis in Electroplating

Electroplating is one of the most precise, yet also most sensitive, processes in surface technology. Whether for corrosion protection, decorative finishing, or functional coating – the quality of the deposited layer depends significantly on the exact composition and stability of the process baths. This is where in-line analytics comes into play: It allows for the continuous monitoring of parameters such as pH, temperature, conductivity, and ion concentrations – thus offering decisive advantages over manual measurements.

Why in-line instead of manual measurement?

Traditionally, process control in electroplating plants is carried out through random laboratory analyses. However, this method is time-delayed, labor-intensive, and prone to human error. In-line analytics, on the other hand, is based on real-time sensor monitoring, directly in the process bath or in bypass lines. Relevant measured values ​​are available at any time – without having to interrupt the process.

The key advantages

• Real-time data enables rapid response to disturbances (e.g., deviations in pH or metal ions).

• Reduction in scrap and rework, as fluctuations can be immediately identified and corrected.

• Longer bath service life thanks to optimal parameter control.

• Reduced personnel costs for routine analyses.

• Reliable documentation through continuous monitoring for quality assurance and traceability (e.g., according to ISO 9001 or IATF 16949).

One current disadvantage is the limited production speed and capacity. Furthermore, the choice of materials is limited compared to traditional thermoplastics, although significant progress is being made in this area – for example, with high-performance plastics such as PEEK or PA12.

Which parameters are typically monitored?

• pH-value: Crucial for deposition quality and speed. In-line pH sensors use glass-free ISFET technologies or traditional glass electrodes with automatic temperature compensation

• Temperature: Influences solubility, reaction kinetics, and layer structure. Modern sensors offer ±0.1°C accuracy with immediate feedback.

• Conductivity: Indirect measure of the salt concentration in the bath. Deviations indicate dilution, carryover, or dosing errors early on.

• Ion-selective electrodes (ISE): For the determination of specific metal ions such as Cu²⁺, Ni²⁺, or Zn²⁺ – particularly relevant for multi-component baths or automated dosing.

Integration into existing electroplating systems

A common misconception: In-line analysis is only economically viable in new, highly automated systems. However, modern systems can be easily retrofitted thanks to modular sensors and standardized interfaces (e.g., 4–20 mA, Modbus, Profinet). Many suppliers enable plug-and-play integration into existing process control systems (PLC, SCADA, MES).

In addition, in-line analysis can be coupled with dosing systems for fully automated replenishment of electrolytes or buffer solutions. This creates a closed control loop that ensures consistent process quality – a true game changer in terms of resource efficiency and reproducibility.

Conclusion

In-line analytics takes electroplating technology to a new level: away from reactive troubleshooting and toward proactive process control. Continuous monitoring of key parameters not only increases coating quality but also reduces operating costs, material usage, and downtime. Especially in times of growing demands for sustainability, documentation, and traceability, in-line analytics is a key component of future-proof manufacturing concepts.

Sources and Literature

1. Vetter, W., & Kanani, N. (2000). Galvanotechnik – Grundlagen und Praxis. Carl Hanser Verlag.
2. Bundschuh, M., et al. (2021). Process analytical technologies in electroplating – Current developments and future trends. Surface and Coatings Technology, 425, 127672. DOI: 10.1016/j.surfcoat.2021.127672
3. Meyer, M. (2019). Inline-Messtechnik in der Oberflächentechnik: Anwendungen und Herausforderungen. Galvanotechnik Journal, 110(7), 46–51.
4. IEC 62828-1:2020. Reference conditions and procedures for measuring the performance of online sensors in process industries.
5. Lutz, J., et al. (2017). Advanced sensor technologies for inline control in electrochemical surface treatments. Electrochimica Acta, 258, 846–855. DOI: 10.1016/j.electacta.2017.11.03