XRF analysis for coating thickness and composition is fast, efficient, non-destructive, and very accurate. However, some analysers may not include features that will make your life easier and some may be overly complex with features you won’t use. To make sure you buy an analyser that’s right for your application and budget, here’s a list of the top five things you need to know.
The chamber you choose will depend on the size and shape of your parts, as well as how you intend to position them for analysis. It must be large enough to fit the part and hold it in the right position to get a good measurement. If your part is curved or complex in design, you’ll need to rotate it so that the X-rays hit the surface at a right angle; if not, you’ll get the wrong result. It’s common for complex shapes to be held in place with a purpose-built fixture that must also fit inside the chamber. If your parts are thin, it can sometimes be faster to load them through a slot in the chamber rather than opening the chamber door. Your chamber choice needs to take this all into consideration.
The collimator is the part of the analyser that directs X-rays towards the sample. The collimator size dictates the size of the part or feature that you can measure, as well as precision and measurement time needed to get the desired results. If the collimator is too large, the target beam will be larger than your part or feature area and the results will include what’s around the sample – this adds errors to your measurements. If the collimator is too small, you will need to increase the measurement time to keep your plating line under control. Ideally, you’ll need a collimator that’s as large as possible, while remaining within the boundaries of the parts. If the size of your parts varies, it may be beneficial to select an XRF with multiple collimator shapes and sizes that can selected easily from within the software.
XRF analysers are made with two main types of detector: proportional counter and silicon drift detector (SDD). A proportional counter is more traditional, whereas the SDD offers advantages for more complex coatings. Both of them are perfectly adequate for many coatings applications, but the SDD has better resolution, which becomes important if you have a lot of elements in your sample that are close to each other in energy level (how they are measured by the instrument). If your plating lines change frequently, the higher resolution SDD detector may be worth the additional cost to help future-proof your purchase.
Your XRF analyser will be setup and calibrated for measuring coating thickness and composition. However, because it’s easy to run a calibration for other elements, you can use the same piece of kit to test for other things, such as:
Plating bath chemistry
Instead of wet chemistry or techniques that involve additional preparation, simply pour a small amount of the bath into the prepared cup, pop it into the unit and take the measurement. In less than a minute, you have a read out of the bath solution composition. This allows you to test more frequently and better control bath chemistry.
Incoming materials check
You can use XRF to check incoming base metal composition and grade before adding them to your warehouse or lining them up for plating. Testing before you’ve applied the coatings is the best way to avoid costly mistakes and customer issues.
RoHS and Pb-free analysis
Some XRF analysers can be used for screening restricted materials. Now, there’s no single technique that can check for every substance, but as XRF has such a broad elemental range, it allows you to screen for a lot of the main hazardous elements, such as lead, cadmium and mercury.
Once you have set the hardware and analytical requirements, it is time to think about how you and your operators will interact with the instrument. And this is where the software makes the difference. Look for software that makes the instrument easy to operate and adds value. For example, you can use your XRF analyser for root cause analysis in production by using the qualitative mode to look for contaminants or mistakes. Software modules are also available that allow you to build up a map of the sample surface to check for uniformity. Setting up calibrations and reporting formats are important for taking on new jobs and customers, make sure you will be comfortable handling these tasks.
Hitachi’s range of XRF analysers are available with many different configurations. You can select software modules, detector type, chamber design and collimator configuration. We supply traceable calibration standards and reference samples to get the instrument set up quickly and easily. And as always, Hitachi’s team of product specialists are ready to help you with any questions you may have.
For more information on the analyser that’s right for your coatings facility, please get in touch.