Understanding the characteristics of various conformal coating types, and their interactions with the extreme range of products and materials to which they are applied, ensures optimal function, performance reliability and product-life. Designers and users of conformal coatings should be aware of the properties of various types of conformal coatings and their interactions with the parts/materials they cover, to protect the products in their respective end-use environments for the expected design-life of each component.Read More
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Printed circuit boards are extremely susceptible to a wide range of contaminants that can significantly damage or ruin them in a relatively short period of time. These contaminants include moisture, dust, and harmful chemicals. In addition, electronic circuits are also susceptible to extreme temperatures and environments.
Type AR (acrylic resin) conformal coatings are a popular choice for conformal coating projects because of their moisture protection, low cost, and ease of application. There are many different varieties of type AR conformal coatings such as:
Nexus3C, the Conformal Coating Centre, have arranged a program of workshops and conferences over the next twelve months across North America, Asia and Europe for users of conformal coating.
- HumiSeal 1A33
- HumiSeal 1A20
- Humiseal 1A27
- Humiseal 2A64
- HumiSeal 1A34
- Hysol PC18M
- CONATHANE CE-1155-35
- CONAP CE-1170
- CONATHANE CE-1164
- Techspray Fine-L-Kote
- MG Chemicals 4223
- Electrolube PUC
You should consider using type ur conformal coating whenever your application has any issues with chemical resistivity as type ur coatings are very resistant to chemical solvents. Type ur conformal coating is also smart to include in any tin whisker mitigation strategy, as NASA studies have shown that urethane conformal coatings are one of the few ways to successfully mitigate tin whisker growth. Finally, applications that can see any direct mechanical wear against the coating should consider urethane conformal coatings as well.
Tin whiskers are electrically conductive, crystalline structures of tin that sometimes grow from surfaces where tin (especially electroplated tin) is used as a final finish. They typically grow from lengths of 1-2 millimeters (mm) but have been observed to lengths in excess of 10 mm. They are a serious issue in the electronics world because they have been known to cause short circuits between circuit elements.
NASA-STD 8739.1 is the Workmanship Standard for Polymeric Application on Electronic Assemblies, which describes NASA’s technical requirements, procedures, and documenting requirements for staking, conformal coating, bonding, and encapsulation of printed wiring boards and electronic assemblies. Included are requirements which establish the responsibility for documenting, fabrication, and inspection procedures to be used for NASA work including supplier innovations, special processes, and changes in technology. NASA-STD 8739.1 was initially released in August of 1999, with improvements and minor changes to the standard in recent years. The current up-to-date revision is NASA-STD 8739.1A with Change 2.