Quantitative Analysis of Amount of Deposition and Plating Thickness: Multilayer and Irregular Shaped Sample

Importance of the Topic

In manufacturing and materials research, precise measurement of deposition and plating thickness is essential for quality assurance and performance reliability. X-ray fluorescence (XRF) spectrometry offers rapid, non-destructive quantification of elemental layers and is widely adopted in industries from electronics to corrosion protection.

Study Goals and Overview

This study demonstrates the capabilities of the Shimadzu EDX-7200 energy dispersive XRF spectrometer to:

• Quantitatively analyze a three-layer Au/Ni/Cu plating standard
• Convert deposition mass to layer thickness
• Apply a novel background fundamental parameter (BG-FP) method to irregularly shaped samples such as zinc-plated iron screws

Methodology and Instrumentation

Instrument: Shimadzu EDX-7200 equipped with a silicon drift detector (SDD) and Rh target X-ray tube.
Analytical approaches:

• Thin film FP method for flat multilayer standards
• BG-FP method using scattered X-ray intensity to correct for geometry effects in non-flat samples

Standard sample: NMIJ CRM 5208-a (20×20 mm) with 184 μg/cm² Au, 869 μg/cm² Ni, 880 μg/cm² Cu.
Irregular sample: Zinc-plated iron screw with distinct smooth head and threaded shaft.
Measurement parameters: 50 kV tube voltage, integration time 100 s, air atmosphere, no primary filter for Zn and Fe.

Main Results and Discussion

Multilayer Standard:

• Measured deposition mass: Au 176 μg/cm², Ni 861 μg/cm², Cu 861 μg/cm²; deviations <5 % from certified values
• Converted thickness: Au ~91 nm, Ni ~1041 nm, Cu ~937 nm
• Repeatability (10 cycles): coefficient of variation <1 % for all layers, demonstrating high measurement precision

Irregular Sample:

• Smooth head measured by thin film FP: 4.08 μm Zn layer
• Threaded shaft: thin film FP underestimated thickness, while BG-FP method corrected geometry effects to yield 4.29 μm, matching the smooth head result
• Qualitative spectra confirmed clear Zn peaks and consistent scattered X-ray signals used for BG-FP correction

Benefits and Practical Applications

The EDX-7200 offers:

• Enhanced sensitivity and faster counting rates compared to previous models
• Non-destructive analysis of multilayer coatings without sample preparation
• Accurate quantification on complex geometries using BG-FP, applicable to screws, springs, and curved surfaces
• Quantitative range from nanometers to micrometers, supporting diverse industrial needs

Future Trends and Possibilities

Emerging directions include:

• Integration of automated in-line XRF monitoring for real-time process control
• Expanded material libraries and advanced FP algorithms for broader coating systems
• AI-driven data analysis to accelerate interpretation and anomaly detection
• Miniaturization of XRF spectrometers for field and on-site applications

Conclusion

The Shimadzu EDX-7200 demonstrates robust performance for both flat and irregular samples, delivering high accuracy, precision, and operational ease. The combination of thin film FP and BG-FP methods enables comprehensive, non-destructive characterization of plating thickness across diverse applications.

Reference

H. Moriya and A. Urushizaki, “Quantitative Analysis of Amount of Deposition and Plating Thickness: Multilayer and Irregular Shaped Samples,” Shimadzu Application News, First Edition Dec. 2021.