One-part fluorosilicone gel materials for automotive sensor applications

Silicone gels are widely utilized in automotive electronic applications as encapsulants and potting materials. Silicones offer stress relief and protection for electronics, and fluorosilicones offer the added benefits of high-temperature stability and low swell in solvents like automotive fuels and other fluids. This protection is critical for sensors immersed in automotive fuel environments. Two new technologies using fluorosilicone backbones have been developed for the automotive electronics market. The first material is a single-component Fluorogel(TM) heat cured product. A soft gel is obtained after a 10-15 minute/125 degrees C cure for small samples, with larger samples requiring longer times and/or higher temperatures. This material has excellent electrical properties, suitable for direct contact with sensors. The solvent resistance was designed to maintain gel integrity during immersion in gasolines. High temperature resistance has been demonstrated by the minimal hardening observed after thermal aging at 150 degrees C for 1000 hours. The viscosity of the current material is in the range of 500-1000 cat. The second one-part Fluorogel(TM) material utilizes a UV cure mechanism. A 1 cm deep sample of this material cures to a soft gel (under 2800 ml/cm(2) of ultraviolet radiation) in approximately 30 seconds. This material has all the features of other fluorosilicone gels, with the additional advantage of fast cure under UV exposure, reducing the stress that would be placed on the sensor and leads during cure of a heat-activated product.