X-ray instruments help to comply with WEEE, RoHS

X-ray instruments automate analysis procedures, are fully enclosed, and can be operated with basic skill levels in the factory with minimal safety requirements.

EU politicians have decreed a ban or a limit on certain materials that pollute or harm the environment, generating the new EU regulations, RoHS and WEEE.

It affects lead (Pb), mercury (Hg), hexavalent chromium (Cr VI) and cadmium (Cd) as well as polybrominated biphenyls (PBB) and polybrominated diphenyl ethers (PBE).

After the EU regulations become effective in the UK on July 1, 2006, only 1000 ppm (parts per million) of all these materials, and only 100 ppm for cadmium will be allowed in virtually all products manufactured or sold in the EU.

Manufacturers of electrical and electronic equipment will find themselves particularly challenged as they will only be able to market those products and components that conform to the required minimum levels of harmful substances.

In particular, printed circuit boards, electronic components and solder connections as well as enclosures and single components made of synthetics, must be measured and tested.

To demonstrate conformity with the EU guideline, manufactures must continually analyse the materials of these components.

Conducting this analysis using the X-ray fluorescence method has many advantages.

* The advantage of screening first - the X-ray fluorescence method is especially economical for screening the components as a first step of the inspection process.

Personnel without special knowledge of analysis methods can easily identify specimens that are clear of harmful substances.

Components that are at the critical borderline or above can then be analysed quantitatively or rejected.

The supplier can then be required to provide a detailed analysis or replacement parts.

* Automated Analysis - the Fischerscope X-ray XAN and XDAL, from Fischer Instrumentation (GB), automates the analysis procedure.

The instruments are fully enclosed and can be operated with basic skill levels in factory, laboratory or even office environments with minimal safety requirements.

No prior preparation of the sample is required before measurement, so no damage is done to the component, the measurement chamber is large enough to take sub-assemblies and complete PCBs.

The XDAL has a programmable XY stage so many components can be analysed unattended.

PCBs can be automatically scanned to identify any non-conforming component.

The results are displayed in tabular form with the material concentrations that exceed the permitted limits emphasized in colour (red) on the screen or in the printout.

* Speed and economy of analysis - the accurate analysis of chromium and bromine in the components significantly simplifies the otherwise difficult detection of Cr (VI), PBB and PBE concentrations.

If the amounts of chromium and bromine are below the permitted quotas, then the same holds true for Cr (VI) or PBB and PBE.

Therefore, other time and cost-intensive analysis methods can be avoided by the use of X-ray fluorescence instruments.

Analysis with the Fischer instruments takes between 50 to 200s, depending on the dimensions of the components to be measured.

The detection limit of lead, mercury and bromine is below 10 ppm, for cadmium and chromium below 20 ppm.

As the instruments use a range of collimators, very small specimens, or areas on specimens, can be measured and analysed, using a video camera for precise positioning.

This allows, for example, the analysis of lead and cadmium in narrow PCB tracks and the smallest soldering pads.

* Coating analysis of several layers of differing alloys - a particular strength of these instruments is their capability for analysis of complex coatings.

In practical applications, it is often necessary to examine electronic components comprising several layers of differing alloys.

The extremely difficult challenges of 'reading' the correct concentrations and individual coating thicknesses from the fluorescence spectra of such coating systems are achieved by the complex WinFTM V.6 measurement and control software, together with the high precision measurement electronics.

Thus banned material under a benign top layer can be identified.

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