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OCTOBER 2022 I DESIGN007 MAGAZINE 73 surfaces can accelerate corrosion under the right environment. e challenge for a confor- mal coating is to achieve good coverage and adhesion to the complex, three-dimensional topography of a PCB. Poorly performing coat- ings also risk loss of insulation at the PCB sur- faces when water condenses in combination with ionic impurities to form conductive path- ways between PCB tracks. Without doubt, condensation can severely test the insulation resistance of a coating. Avoiding coating pitfalls is a fine balance of material selection, understanding the engi- neering requirements for coverage, and thick- ness, as well as choosing a suitable applica- tion method. Understanding the intricacies of conformal coatings will pay off in determining a successful coating outcome. ere's a great deal more to discuss and over the following months I hope to provide more useful tips and advice that will help you accomplish reliable circuit protection. DESIGN007 Saskia Hogan is global product manager, conformal coatings, at Electrolube. To read past columns from Electrolube, click here. Download your free copy of Electrolube's book, The Printed Circuit Assembler's Guide to… Conformal Coatings for Harsh Environments, and watch the micro webinar series "Coatings Uncoated!" influence the methods that are suitable for application of the coating. Certain materials, such as moisture-curing or UV-curable mate- rials, are difficult to use in a dip process due to the material curing prematurely, so it could be said that the choice of coating is indirectly related to the board design. Factors such as operating temperature range, temperature excursions (such as thermal shock and thermal cycling), corrosion, condensation, and resis- tance to chemicals, solvents, and water are all key in determining the successful outcome f or a coating. Working with an experienced provider can help you navigate which coat- ing is best for your application and advice on methods. Consider the Two Primary Failure Mechanisms Aside from insufficient planning at the design stage, a poorly applied coating, or ignoring pre-coat cleaning, two of the most common reasons for coating failure include corrosion and loss of insulation, which leads to short cir- cuits. Corrosion is a complex process that takes place on an exposed metal surface, usually in the presence of water and ionic contaminants. Cleaning prior to conformal coating will go a long way toward removing these two pre-req- uisite conditions for corrosion as coatings help prevent the formation of electrolytic solutions by acting as moisture barriers. However, small voids in the coating that expose a PCB's metal