Silicones and Electronics
Long-term, reliable protection of sensitive circuits and components has become increasingly more important in many delicate and demanding electronic applications. Silicones function over a wide temperature and humidity range as durable dielectric insulation, as barriers against environmental contaminants and as stress-relieving shock and vibration absorbers. In addition to sustaining their physical and electrical properties over a broad range of operating conditions, silicones are resistant to ozone and ultraviolet degradation and have good chemical stability. Most Dow silicones contain significantly less solvent than organic coatings and are available in a wide variety of cure systems.
Conformal coatings are materials applied in thin layers (typically a few mils or microns) onto printed circuits or other electronic substrates. They provide environmental and mechanical protection to significantly extend the life of the components and circuitry. Conformal coatings are traditionally applied by dipping, spraying or simple flow coating, and increasingly by select coating or robotic dispensing. Conformal coatings protect electronic printed circuit boards from moisture and contaminants, preventing short circuits and corrosion of conductors and solder joints. They also minimize dendritic growth and the electromigration of metal between conductors. In addition, the use of conformal coatings protects circuits and components from abrasion and solvents. Stress relief is also provided, as is protection of the insulation resistance of the circuit board. Dow coatings are particularly useful for protecting circuitry in severe-service environments, while maintaining a low-stress environment for components and connections. These severe environments range from everyday temperature and humidity extremes seen in consumer electronics to the more harsh automotive under-hood environment, up to the extreme conditions demanded in military or industrial applications. The coatings are supplied in a variety of forms that can be cured at room temperature or accelerated by heat, adaptable to your processing needs. Most conformal coatings contain a UV indicator enabling blacklight visualization of the coating.
Dow Conformal Coatings are supplied in three product families:
- Solventless RTV elastomeric conformal coatings require atmospheric moisture to cure. This family of coatings is rapidly gaining popularity due to its environmentally friendly and solventless formulations, its rapid cure rates that can be dramatically accelerated by mildheat, and its cost effectiveness. These elastomers, when cured, offer the optimum stress relief for components and interconnections in a variety of service environments.
- Solventless heat cure conformal coatings are designed for rapid processing at moderate temps (above 100 °C). They require some heating to cure, offering long bath life at room temperature. Like the room-temperature-curing elastomers, these products offer optimum stress relief for components and interconnections in a variety of service environments. This product line also features coatings that are manufactured for controlled volatility.
- RTV elastoplastic conformal coatings have firm, dry surfaces for better handling and abrasion resistance after cure. They require atmospheric moisture to cure and their cure rates can be accelerated by mild heat. They are supplied in solvent, with low-VOC versions available.
Conformal coatings provide a "thin section" solution for circuit boards requiring protection from moisture, chemicals, vibration and other contaminates.
UV7993 is a UV acrylated urethane system that offers tough, chemical resistance while maintaining a low stress resiliency for sensitive components. This fast curing system is widely used for white goods, appliances and commercial/industrial applications.
SC3613 is an industry standard for applications demanding microelectronic grade purity as circuits are protected within a soft, silicone medium from dust, contaminates and vibration environments. This silicone coating offers high temperature performance often required from automotive and industrial circuit manufacturers.