Silicone Optical Encapsulants

DOW Silicones (formerly Dow Corning) delivers a wide variety of silicone-based polymers for diverse solutions in electric, electronic and energy applications. DOWSIL™ and SYLGARD™ silicone encapsulants (or pottants) are protective materials used to completely embed electronic circuitry. Typically, they are used to protect circuits from the harmful effects of moisture and other contaminants, provide electrical insulation for high voltages and also protect the circuit and interconnections from thermal and mechanical stresses. Encapsulants are typically applied in thick layers – exceeding 125 mµ.

DOWSIL™ and SYLGARD™ encapsulants are supplied as solventless, two-component liquid component kits. Many are designed for a 1:1 mixing ratio (parts A and B). When the two liquid components are thoroughly mixed, the mixture cures to a flexible elastomer. Some products will cure at room temperature while others are designed to be cured by heat.

DOWSIL™ and SYLGARD™ silicone optical encapsulants offer a wide range of hardness, cure profiles and viscosities. The class of optical encapsulants is highly transparent and shows, depending on the chemical structure, a refractive index as high as 1.42. The key benefit of DOWSIL™ and SYLGARD™ optical silicone materials is its moisture resistance, which provides long-term protection for LED chips, as one example.