RoHS test technique comes under scrutiny

“The reason behind this is lack of confidence when using this technique for RoHS,” project head Dr Chris Hunt told EW.

XRF testing determines which elements are present in a sample and involves firing a beam of X-rays at a sample and examining the returning electromagnetic spectrum. Handheld and more sophisticated benchtop testers are available.

What motivated the project was concern among a group of organisations that not enough experience exists in the industry to know if consistent and accurate results are being achieved.

“0.1 per cent is quite demanding for these machines,” said Hunt. “They can do it under certain circumstances. Some things can be difficult to see.”

The project, funded jointly by the DTI and the ten industrial partners, comes in two parts.

“We will get a range of samples, and the partners will measure them with the different XRF instruments they own,” said Hunt. “Then we will use chemical analysis to see accurately what is in the samples.”

Correlating the results should indicate when XRF can be used reliably and how the machines compare with each other. It will also allow the partners to remove errors in their systems.

In the second part of the project, said Hunt, NPL will make up standard samples with known quantities of contaminants to allow firms to calibrate their own XRF test set-ups.

The project starts now and will continue for six months, after which a detailed report will be produced for the project partners, including all data collected.

The work will be presented to the SSTC (NPL Soldering Science and Technology Club) and disseminated in an NPL Report.