For those scratching their heads over how to screen electronic components for RoHS-compliance, Soldertec — part of the UK's Tin Technology — suggests X-rays as a useful alternative to costly and destructive chemical testing. For well-known component suppliers, an accreditation certificate will probably be sufficient, but for suppliers with a vague pedigree, screening may be necessary.
Soldertec suggests using XRF (X-ray florescence). The procedure is quick, easy and non-destructive. The electrons in the shell of the elements present in a sample are disrupted by a low-energy X-ray, and each element responds by producing X-rays at a unique set of energies, which allows each element to be measured. The test takes as little as two minutes. As for limitations, the test is only capable of detecting materials close to the surface, and while it easily detects lead, mercury and cadmium, it cannot distinguish the specific materials PBB, PBDE or hexavalent chromium.