XRF equipment and materials characterization for RoHS compliance: an evaluation of five systems showed broad performance differences.Ed: For the complete article, visit circuitsassembly.com/cms/content/view/5291. We selected two handheld and three desktop XRF XRF X-Ray Fluorescence XRF X-Ray Flash XRF Cross Reference XRF Extended Recovery Facility (IBM) XRF Extended Reliability Feature XRF Cross Reference File XRF External Reference spectrometers because of their main specifications, performance and cost. They are Vendor 1-D, Vendor 2-D, Vendor 3-D, Vendor 4-H and Vendor 5-H. We used this XRF equipment for Cpk, stability, Gage R & R, detection level versus acquisition time studies with 12 standard samples, and correlation studies with 11 production samples. We found: * Energy dispersive dispersive /dis·per·sive/ (-per´siv) 1. tending to become dispersed. 2. promoting dispersion. XRF is one of the more suitable analysis methods for parts screening because of its nondestructive non·de·struc·tive adj. Of, relating to, or being a process that does not result in damage to the material under investigation or testing. non , fast and efficient analysis. * Each XRF has different accuracy levels for measuring banned substances banned substance n (SPORT) → sustancia prohibida banned substance n → sostanza al bando (nello sport) . We suggest obtaining deviation (different) results for main elements of the XRF in order to learn which samples need to be sent to an outside laboratory for confirmation of RoHS compliance. * In general, desktop XRF performed better than handheld XRF. However, the handheld XRF from Vendor 4 performed better than some desktop XRF. Table 19 summarizes the performances. * Choose a reliable test laboratory for identifying samples that are inconclusive INCONCLUSIVE. What does not put an end to a thing. Inconclusive presumptions are those which may be overcome by opposing proof; for example, the law presumes that he who possesses personal property is the owner of it, but evidence is allowed to contradict this presumption, and show who is (in between the RoHS-compliant and noncompliant ranges). * The experiment results listed are primary studies with XRF for RoHS enforcement. The results obtained from this evaluation showed the equipments' capability to quantify banned substances by RoHS initiative and demonstrated that XRF technique is a feasible testing method for manufacturing to perform quick verifications. However, a safety margin must be chosen to prevent equipment uncertainty from affecting final decisions. * Despite the benefits of this technique, important limitations should be considered, such as the inability to quantify PBB PBB: see polybrominated biphenyl. , PBDE PBDE Polybrominated Diphenyl Ether PBDE Pentabromodiphenyl Ether (flame retardant additive in plastics) PBDE Parallel Block-Decodable Encoder and chromium chromium (krō`mēəm) [Gr.,=color], metallic chemical element; symbol Cr; at. no. 24; at. wt. 51.996; m.p. about 1,857°C;; b.p. 2,672°C;; sp. gr. about 7.2 at 20°C;; valence +2, +3, +6. VI; the inability to detect banned substances in the inner part of a thick component/part; the inability to differentiate the banned substance contents of a nonhomogeneous component/part (the XRF result is a sum of different homogeneous materials), etc. A trial run is highly recommended to study effectiveness before final approval. Also, a well-trained operator is required to judge the results. Ed.: This article was first published at Apex in February 2007 and is published with permission of the authors. Hector Rene Marin Hernandez, RefugioVicente Escobedo Alva, Zhen (Jane) Feng, Ph.D., Joao Ofenboeck, and Murad Kurwa are with Flextronics International (flextronics.com); jane.feng@flextronics.com. Hector Rene Marin Hernandez, RefugioVicente Escobedo Alva, Zhen (Jane) Feng, Ph.D., Joao Ofenboeck and Murad Kurwa |
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