| Electronics Residues Testing Methods, Part 3 |
 |
 |
| Written by Terry Munson | |||
| Wednesday, 31 December 2008 19:00 | |||
This month’s analysis looks at x-ray fluorescence. Ed.: This continues a four-part series on typical analysis techniques and their pros and cons in regard to understanding electronics residues.The x-ray fluorescence (XRF) principle is depicted in Figure 1. An inner shell electron is excited by an incident photon in the x-ray region. During the de-excitation process, an electron moves from a higher energy level to fill the vacancy. The energy difference between the two shells appears as a z-ray, emitted by the atom. The z-ray spectrum acquired during the above process reveals a number of characteristic peaks. The energy of the peaks leads to the identification of the elements present in the sample (qualitative analysis), while the peak intensity provides the relevant or absolute elemental concentration (semi-quantitative or quantitative analysis). A typical XRF spectroscopy arrangement includes a source of primary radiation (usually a radioisotope or an x-ray tube) and equipment for detecting the secondary x-rays.1  Applications and limitations. XRF is a quick, nondestructive analysis technique to determine the elemental makeup of a material or mass. Because it uses x-ray to release the electron shell of the materials, it can see and measure the thicknesses of plated lead, but has difficulty with thin-film metals and organic and ionic materials on the surface. However, XRF will see ionic residues in thick concentrations, but is unable to quantify these surface films. Figure 2 shows a dendrite growth caused by partially heat-activated, no-clean flux (succinic, maliec and glutaric acids) and fabrication HASL flux (chloride), but the XRF is not able to determine the contaminants, just the metals and flame retardant (organo bromide).  References
Terry Munson is with Foresite Inc. (residues.com); This e-mail address is being protected from spambots. You need JavaScript enabled to view it . This column appears monthly.
|
Columns
| Semblant Warms to New Fluoropolymer Conformal Coating |
|
Months after hinting at a new conformal coating during a paper session at SMTA International, Semblant has officially launched PlasmaShield. CIRCUITS ASSEMBLY editor in chief Mike Buetow spoke with vice president of worldwide sales and marketing Steve McClure last week. |
| Read more... |
| ECTC in Las Vegas |
What happens in Las Vegas at ECTC, doesn’t stay in Las Vegas, it is shared here. This year’s ECTC, or electronics components technology conference, was held in Las Vegas’ Cosmopolitan, May 28-31. |
| Read more... |
Features
| The Impact of Reel Splicing Kits on Setup and Changeover |
Traditional feeder setup using tape-and-reel can drain time. There’s a quick and better way. |
| Read more... |
| Standard Solar Cells vs. Next-Gen Cells: Which is Winning? |
Overcapacity is stalling the rate of improvement, but only for so long. |
| Read more... |
Search
Search
Login
CB Login
Language
Language
Products
Viscom Announces SI 7.46 AOI Software Release
Software release SI 7.46 reduces AOI inspection times through improved optimization of travel paths. Integrates Library Manager to assign new inspection patterns more quickly and easily, easing use...
Software release SI 7.46 reduces AOI inspection times through improved optimization of travel paths. Integrates Library Manager to assign new inspection patterns more quickly and easily, easing use...
