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JULY 2018 I DESIGN007 MAGAZINE 63 to salt-spray then the likelihood of failure will increase significantly. Test, Test and Test Again Environmental testing methods are the key to ensuring that coatings are fit for purpose and will stand up to the most rigorous of conditions. But what exactly is environmental testing? In its basic form, environmental testing is conducted on a material to ascertain its performance characteris- tics under controlled environmental conditions as close as possible to those in which the product may reasonably be expected to perform. Examples include, but are not limited to, the following: extremely high and low temperatures; rapid excursions of temperature sufficient to impose thermal shock; salt spray and salt fog; very high humidity or condensing conditions; saturated environments; exposure to fungal growths, corro- sive gases and solar radiation, and high and low atmospheric pressures (especially for aeronautical and space equipment). In addition to understanding how well the mate- rial tolerates each individual condition, these spe- cific tests form the basis for sequential testing by a combination of methods to evaluate the cumula- tive effects of harsh environments. A coated board will be subjected to a variety of environmental impacts, not just one. The conditions and expo- sures should be chosen to be representative of what could reasonably be expected in a real life, end-use environment. So, there you have it. Environmentally friendly materials are available now and new developments are coming online. As their performance gradually improves, with time these materials will open new avenues for compliance across many disciplines. A cautionary note for the present, however: Test your water-based conformal coating thoroughly and ensure that it meets your immediate needs while delivering a guaranteed level of protection. DESIGN007 Phil Kinner is the global business/ technical director of the coatings division of Electrolube. He is also the author of The Printed Circuit Assembler's Guide to... Conformal Coatings for Harsh Environments. A Step Closer to Single-Atom Data Storage In a new study published in Physical Review Letters, physicists at EPFL's Institute of Physics have used Scanning Tunneling Microscopy to demonstrate the stability of a magnet consist- ing of a single atom of holmium, an element they have been working with for years. "Single-atom magnets offer an interesting per- spective because quantum mechanics may offer shortcuts across their stability barriers that we could exploit in the future," says EPFL's Fabian Natterer who is the paper's first author. "This would be the last piece of the puzzle to atomic data recording." Using a scanning tunneling microscope, which can "see" atoms on surfaces, the scientists found that the holmium atoms could retain their magnetization in a magnetic field exceeding 8 Tesla, which is around the strength of magnets used in the Large Hadron Collider. The authors describe this as "record-breaking coercivity," a term that describes the ability of a magnet to withstand an external magnetic field without becoming demagnetized. "Research in the miniaturization of magnetic bits has focused heavily on magnetic bistability," says Natterer. "We have demonstrated that the small - est bits can indeed be extremely stable, but next we need to learn how to write information to those bits more effectively to overcome the magnetic 'tri - lemma' of magnetic recording: stability, writability, and signal-to-noise ratio." Click here for more.

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