Novel Approach Unveils Elemental Composition and Properties of Recycled Printed-Circuit Board (PCB) Powder

Recently, Shintaro Ichikawa of Fukuoka University and his team investigated the chemical states and elemental composition within a printed-circuit board (PCB) powder. Their findings were published in Spectrochimica Acta Part B: Atomic Spectroscopy, revealing new insights into metal recovery processes from electronic waste (1).

Circuit board | Image Credit: © jules - stock.adobe.com

Ichikawa and his research team obtained the powdered sample of the PCB through cryo-milling, which is the process of using liquid nitrogen to lower the temperature of the sample prior to grinding into aa fine powder (1). Then, they analyzed its elemental composition using advanced techniques such as X-ray fluorescence (XRF) and X-ray diffraction (XRD). Using XRF and XRD analysis, the research team examined the various particle fractions, uncovering various elements distributed in the powder, including aluminum (Al), silicon (Si), calcium (Ca), iron (Fe), nickel (Ni), copper (Cu), tin (Sn), barium (Ba), and lead (Pb) (1).

The particle-size distribution revealed distinct fractions, with sizes ranging from 27 to 500 μm. These fractions exhibited specific elemental concentrations, categorizing the components into coarse, moderately sized, and fine-particle fractions, each containing various elements based on their tendencies for accumulation (1).

The researchers discovered through analysis of the particles that the metallic components like aluminum and nickel showcased durability owing to their high ductility, whereas ceramic materials such as calcium carbonate (CaCO₃) and barium titanate (BaTiO₃) concentrated in the fine-particle fraction because of their fragile nature.

The research team also used multivariate statistical analyses to learn more about the amorphous components in the powder. They discovered that they were comprised of silicon, calcium, bromine, and tin (1). This distinction in components' chemical states unveiled varying durability properties among the PCB constituents.

The detailed diffraction patterns unveiled the chemical forms in which elements existed within the PCB powder, such as metallic aluminum and Al₂O₃, metallic silicon, Fe₃O₄, metallic nickel, metallic copper, BaTiO₃, and PbZrO₃ (1).

Understanding the elemental composition and durability properties of PCB components can lead to the creation and implementation of improved recycling techniques for electronic waste. By deciphering the distinct properties of these components based on their chemical states, this research provides a roadmap for targeted recovery processes, ultimately contributing to sustainable electronic waste management.

To conclude, the researchers characterized the ground PCB powder using XRF and XRD. Their study contributes to our understanding of the makeup of PCB powder. The findings in this study can help lead to improving current environmentally conscious practices in electronic waste recycling. As a result, Ichikawa and his team helped contribute to the pursuit of establishing more green, sustainable practices.

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Reference

(1) Ichikawa, S.; Hirokawa, Y.; Kurisaki, T.; Nakamura, T. Characterization of a printed-circuit board by X-ray fluorescence and X-ray diffraction analyses for metal recovery. Spectrochimica Acta Part B: At. Spectrosc. 2023, 210, 106819. DOI: 10.1016/j.sab.2023.106819