Implementation of lead-free soldering materials into electronic manufacturing requires inspection of components, manufacturing processes and finished goods, to validate compliance with respect to current global mandates.

X-ray fluorescence (XRF) analyzers are widely accepted by the electronics manufacturing industry as an accurate, repeatable non-destructive process to test for the presence of lead without delaying production schedules. Many analyzers provide qualitative simultaneous identification of elements and replacement materials.

By combining portability and ease of use, hand-held analyzers provide a unique technology resource to support incoming inspection in the stockroom, monitor production floor operations during product assembly and when required, support offsite inspection to validate compliance. The EMPF currently employs the Niton XLt 800 handheld XRF Analyzer (Figure 5-1) to inspect, identify and validate materials used in electronic manufacturing for lead-free compliance.

How does XRF work?
XRF analyzers determine the chemistry of a sample by measuring the spectrum of the characteristic x-rays emitted by the different elements in the sample when it is illuminated by high-energy photons (x-rays or gamma rays). A fluorescent x-ray is created when a photon of sufficient energy strikes an atom in the sample, dislodging an electron from one of the atom's inner orbital shells (lower quantum energy states). The atom regains stability, filling the vacancy left in the inner orbital shell with an electron from one of the atom's higher quantum energy orbital shells. The electron drops to the lower energy state by releasing a fluorescent x-ray, and the energy of this fluorescent x-ray (typically measured in electron volts, eV) is equal to the specific difference in energy between two quantum states of the dropping electron.

Because the quantum states of each electron orbital shell in each different type of atom (each of the atomic elements) are different, the energies of the fluorescent x-rays produced by different elements are also different. When a sample is measured via XRF, each element present in the sample emits its own unique fluorescent x-ray energy spectrum. By inducing and measuring a wide spectrum of the range of different characteristic fluorescent x-rays emitted by the different elements in the sample, Niton's hand-held XRF analyzers can rapidly determine the elements present in the sample and their relative concentrations, in other words, the elemental chemistry of the sample. For samples with known ranges of chemical composition, such as common grades of metal alloys, Niton analyzers can also identify many sample types by name.

Niton XRF analyzers quantify elements ranging from sulfur (element number 16 in the periodic table) through uranium (element number 92) to the heaviest transuranic elements, measuring fluorescent x-ray energies from two thousand electron volts (2 keV) up to 100 keV. Up to 30 or more elements may be quantified simultaneously by measuring the characteristic fluorescence x-rays emitted by a sample.

Features
The XLt 800 has a range of functions that make it a valuable tool in either the factory, the warehouse, or the analytical lab. The 800 series, like other models from Niton, has PC connectivity via a bluetooth interface for quick off loading of data collected from samples. There is also a built in barcode reader to catagorize samples. Additionally, the 800 series comes with 2 rechargable 6-8 hour Li-ion batteries, and an internal storage capacity of up to 3,000 samples, which allows for near continuous operation.

Verification of materials to be used in a manufacturing process will not only help one to achieve compliance with new environmental standards, but will also help to prevent problems that might stem from mixing materials that lead to possible maintenance and reliability issues.

For more information on the Niton XRF Analyzer, or to arrange for a demonstration, Please contact Robert Berta at (610)362-1200 x253, or via email at rberta@aciusa.org.