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Conformal Coating is the process by which material is applied to electronic circuitry to provide protection against such elements as heat, moisture, mis-handling, and dust.  Conformal coating technology has become a vital part of many manufacturing operations to assure reliable, long-life performance of the finished assembly under adverse conditions, particularly high atmospheric humidity.  Closer conductor spacings, tighter packaging densities, and increasing performance requirements demand the protection provided by conformal coatings.

Application
Spraying is the most popular and fastest method for applying conformal coatings.  With the proper combination of solvent dilution, nozzle pressure, and pattern, reliable and consistent results are obtainable.  The majority of our coating application process at CMA is spraying, utilizing compressed air and quality spray equipment to achieve the most consistent, uniform finish.

Brush coat is the least effective application method because of difficulty in achieving uniform coverage and thickness, and controlling bubbling. The Brush coat method is used at CMA primarily for touch-up, considerably small PCB’s and/or components and customer instructed application to specified areas of a PCB.

Dip method is the process in which a masked assembly is immersed in a tank of liquid coating and withdrawn.  The Dip method is the least used application at CMA.

Coating Material
The common types of coatings-

AR  –  Acrylic
UR  –  Urethane
SR   –  Silicone
ER   –  Epoxy

XY  –   Parylene

Coating selection is influenced by engineering or performance characteristics of the cured coating as well as by application or processing characteristics, which affect the physical and chemical properties of the coating as a liquid.

Selection of the proper conformal coating is a major task because of the great number of materials on the market.  That is why CMA works closely with its coating supplier to help potential customers determine the most effective coating based on the specific environmental exposure of the customer’s product.

The Process
CMA is a full service conformal coating provider from moisture pre-baking (if required by customer), to masking, coating application, de-masking, touch-up and 100% inspection under UV lighting.  CMA inspects all work to IPC-A-610 Class 3 standards.