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Design007-Sep2021

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20 DESIGN007 MAGAZINE I SEPTEMBER 2021 For this month's column, I'm going to exam- ine the main methods for achieving the best outcome for your conformal coating process, ultimately increasing the protection afforded by your coating and lifetime of your product. Let's start at the very beginning, at the design stage, factoring in careful consideration for coatings and highlighting the potential for problems during production. is will have a positive impact in the long term and avoid excessive time and expense, resolving prob- lems at a later stage. Another important fac- tor for successful coating is selecting the right coating for the job. is could be an acrylic, a polyurethane, a silicone, a UV cure, a two- part (2K) system, or even a water-based coat- ing. Whilst the design of the board doesn't directly affect the choice of coating material, it will determine which methods can be used to apply the coating. Certain materials, such as moisture curing, 2K or UV curable materials, 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. Similarly, board design will affect the production yield. Consider maximising the distance between components that must be coated and those that must not. e greater the distance between them, the more the production staff will thank you. As a rule, 2 mm is the absolute minimum clearance between coat/no-coat areas, but 5 mm will make an enormous difference in the coating cycle time and success. 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 for a coating. How Important is Coating Application? Do not underestimate this element. Probably the single biggest influ- ence on coating success is as a direct result of how well the coating is applied. e application method of How to Increase the Reliability of Conformal Coatings Sensible Design by Phil Kinner, ELECTROLUBE

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