PRODUCTS & PROCESSES
XRF Analysis : What Labs - and Lines - Really Want – and New Features That Get Them There
Everyone ’ s ultimate goal : minimal variation , maximum speed
by : Paul Vanden Branden , SciMed
Innovations in the electronics and other technologyrelated industries have birthed several trends that impact both product designers , and those charged with assuring that what was designed . . . is what was manufactured . One of the most important trends is the requirement for precision in the composition and deposition of the metal plating - or plating layers - that enables functionality .
The Bowman G Series XRF from SciMed uses a motorized Z-axis with laser auto focus .
The polycapillary optics of Bowman XRF systems from SciMed accelerate photon counting .
These optics also deliver a clean excitation beam . The most advanced XRF systems have a spot size of 7.5 microns , allowing them to measure the smallest features . As a bonus , polycapillary optics enables very short test times .
Z Protection with Laser Scanner
Measuring plating thickness , and identifying individual plating layers , is typically tasked to XRF systems . For every manufacturer , the objectives are threefold : to do and document as much testing as practical , to minimize errors from operators or equipment , and to maximize efficiency through tools such as “ travelers ,” which track a sample ’ s ID throughout manufacturing and testing .
Analysis is often done both in-line ( following various production stages ) and in the lab . The wants and needs of those diverse camps have resulted in a series of innovations that benefit both . Here are the 6 most notable :
Polycapillary X-ray Optics
Polycapillary optics is comprised of hundreds of thousands of stand-alone glass channels that collect a large solid angle of X-rays emitted from a diverging source . The X-rays pass through the optics by total internal reflection and are focused to a selected spot with ultra-high intensity . Typical intensity gain compared with the mechanical pin hole aperture ( collimator ) is more than 1000 times .
As samples are positioned on the X-Y-Z stage , the scanner ’ s laser powers up and scans for intrusions ; it stops when the laser detects the sample . The process then repeats to cover the remaining sections of the stage . The table retreats to the highest point at which it stopped , and executes a slow scan , establishing the Z travel range . The x-ray head approaches this position , and the “ No Part Loaded ” message switches to “ ready ,” signaling the process is complete . Subsequently , the head will be unable to move below the position where the sample was located , preventing contact by restricting Z axis travel .
Laser Auto Focus
When measurement tasks were simpler , optical focusing was sufficient for positioning samples . Today , with the definition of “ precision ” continuing to evolve , the roughness of a sample surface often creates an issue , since it easily confounds the auto-focus of an optical device . Technology ’ s answer is the laser focus . When activated , all of the lights in the unit turn off , and the software seeks the center of the laser , which is calibrated at a fixed angle to define the working distance . When located , the software moves the Z-axis to the center of the laser for precise and consistent measurement distance . This feature ensures that samples are within a few microns of the in-focus position for greatest accuracy . Bonus : it does so in two seconds or less .
76 SEPTEMBER 2021 read online : www . surfaceworld . com