Lead in lead-free solder – EDX-720

Importance of the Topic

The restriction of hazardous substances such as lead and cadmium in electrical and electronic equipment has been mandated by regulations including RoHS, WEEE and the German ElektroG. Accurate, fast and non-destructive analytical methods for monitoring these elements are essential to ensure compliance in production, recycling and quality control of electronic components.

Objectives and Study Overview

This study evaluates two complementary techniques for determination of lead and cadmium in electronic materials and polymers. The first part focuses on quantifying lead in solder standards using energy-dispersive X-ray fluorescence (EDX) with the Shimadzu EDX-720. The second part examines cadmium measurement in polymer samples via atomic absorption spectrometry (AAS) using the Shimadzu AA-6300 system.

Methodology and Instrumentation

EDX-720 measurements were carried out on six certified lead-containing solder standards spanning 250–1 830 ppm Pb. A 300 s live time was used for each spectrum, targeting the Pb Lβ1 line. Detection limits were calculated from the calibration curve according to standard criteria (3σ/k·√Iback·T).

AAS determinations of cadmium were performed on polymer digests. Flame atomization covered 0.1–0.4 mg/L Cd, while electrothermal measurements targeted 0.1–0.4 µg/L. Both deuterium and high-speed self-reversal background compensation methods were evaluated to avoid spectral interferences at 228.8 nm.

Used Instrumentation

• Shimadzu EDX-720 energy-dispersive X-ray fluorescence spectrometer
• Shimadzu AA-6300 atomic absorption spectrometer
• GFA-EX7i graphite furnace accessory for electrothermal atomization

Main Results and Discussion

EDX-720 delivered a lead detection limit of 24.8 ppm (300 s analysis) well below the 1 000 ppm regulatory threshold. Reproducibility tests on the 262 ppm standard yielded 259.3 ± 7.4 ppm (CV 2.9 %), demonstrating high precision without sample preparation. The large sample chamber accommodates both solids and liquids, enabling rapid screening across Na–U elements.

AAS calibration for cadmium showed linear response in both flame and furnace modes. Deuterium background correction proved inadequate due to overlap from arsenic and iron, whereas the self-reversal technique ensured accurate baseline subtraction. Routine polymer analyses yielded reliable Cd quantification in compliance with ElektroG requirements.

Benefits and Practical Applications

• Non-destructive, rapid screening of solder and electronic components for lead content
• High sensitivity and reproducibility suitable for regulatory compliance
• Wide elemental coverage (Na to U) in solid and liquid matrices without extensive sample preparation
• Robust AAS workflows enabling routine monitoring of cadmium and other hazardous metals in polymers and consumer goods

Future Trends and Applications

Advances in detector technology, miniaturized XRF modules and integrated fundamental-parameter methods will further reduce calibration needs. Automation of sample handling and data processing will increase throughput for large-scale compliance labs. Emerging regulations on additional elements and nanomaterials will drive adaptation of both EDX and AAS platforms to meet stricter detection limits and broadened analyte scope.

Conclusion

The combined use of EDX-720 and AA-6300/AAS provides a comprehensive analytical solution for monitoring lead and cadmium in electronic and polymeric materials. The methods achieve regulatory detection limits, high precision and minimal preparation, supporting quality control and environmental compliance across the electronics industry.

Reference

No external literature references were provided within the original application note.