Understanding of XRF Technology and Clarification of its Application for RoHS Directives

摘要

RoHS directives require screening and quantification of certain elements and compounds used in electronics components and parts. X-ray Fluorescence (XRF) technology has emerged as an effective tool in the screening process of electronic components. XRF analyzers, bench top and portable, can determine the presence of concerned elements, but not compounds, in a relatively short period of time. XRF technology is an established analytical method for elemental analyses. However, there are certain technical aspects that directly impact the RoHS application that may require further understanding of XRF principles. The quantitative determination of elements for compliance with RoHS directives could be compromised under certain conditions if the fundamental principles of XRF technology are not well understood and adhered to for this application. The most influencing factor in XRF application for RoHS compliance is the ability of an XRF system to excite and induce characteristic x-rays of concerned elements without any interference that may result in either false negative or a false positive indication. Any false indication causes operational difficulties and has financial consequences. This factor is more pronounced in electronic components which are often composed of complex matrices and contain elements that could interfere directly with the characteristic x-rays of RoHS-concerned elements.This paper provides an overview of XRF technology as it is applied to electronic components, the effectiveness and limitations of XRF methods as a screening, and the contributing factors in obtaining accurate measurements.