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Design007-Mar2019

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MARCH 2019 I DESIGN007 MAGAZINE 83 both the material itself and the application process. Fortunately, a new class of conformal coat- ing materials dubbed "2K" (two component) enable a much greater thickness and perfect application coverage to be achieved, resulting in a higher level of protection. Indeed, the per - formance advantages of 2K materials have been positively demonstrated in three of the harsh- est tests that these materials can be subjected to, including powered condensation testing and powered immersion testing in salt-water. If you have any questions or would like more information about choosing and/or applying conformal coatings, there's a wealth of experi- ence to call upon from our technical support team members who will be more than happy to answer your queries and offer expert guid- ance. DESIGN007 Phil Kinner is the global business and technical director of conformal coat- ings at Electrolube. To read past col- umns or contact Kinner, click here. Kinner is also the author of The Printed Circuit Assembler's Guide to… Conformal Coatings for Harsh Environments. Visit www.i007ebooks.com to download this and other free educational titles. Conformal coatings help prevent the forma- tion of electrolytic solutions by acting as mois- ture barriers. However, small voids in the coating that expose the PCB's metal surfaces can acceler- ate corrosion under the right environment. The challenge for a conformal coating is to achieve good coverage and adhesion to the complex, three-dimensional topography of a PCB. Poorly performing coatings also risk insula- tion loss as the PCB surfaces when water con- denses in combination with ionic impurities to form conductive pathways between PCB tracks. Without a doubt, condensation can severely test the insulation resistance of a coating! Protecting Against Condensation, Immersion, and Salt Spray The greatest test of conformal coating per- formance is posed during power up under wet conditions, whether this is due to con- densation, immersion, or salt spray. Liquid water with soluble impurities is electrically conductive, and finding any weak spots in a coating will eventually lead to short circuits at the PCB surface. To provide protection in these circumstances, it is essential to achieve 100% defect-free coverage of the PCB's metal surfaces, which poses a real challenge for Graphene is a promising material for use in nanoelec- tronics. However, its electronic properties depend greatly on how the edges of the carbon layer are formed. Zigzag patterns are particularly interesting in this respect, but until now, it has been virtually impossible to create edges with a pattern. A team of researchers from the Friedrich-Alexander- Universität Erlangen-Nürnberg (FAU) led by Dr. Konstantin Amsharov from the Chair of Organic Chemistry II succeed- ed in developing a straightforward method for synthesiz- ing zigzag nanographene. Their procedure delivers a yield of close to 100% and is suitable for large scale produc- tion. They have already produced a technically relevant quantity in the laboratory. First, the FAU researchers produced preliminary mole- cules, which they then fit together in a honeycomb forma- tion over several cycles—a process known as cyclisation. In the end, graphene fragments are produced from stag- gered rows of honeycombs or four-limbed stars surround- ing a central point of four graphene honeycombs with the sought-after zigzag pattern to their edges. This approach allows scientists to produce large piec- es of graphene while maintaining control over their shape and periphery. This breakthrough in graphene research means that scientists should soon be able to produce and research a variety of interesting nanographene structures. (Source: Friedrich-Alexander-Universität Erlangen-Nürnberg) Large, Stable Pieces of Graphene Produced With a Unique Edge Pattern

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