Conformal Coating

Silicone Conformal Coatings

Silicones are often used for very high- to low-temperature environments.  They provide high humidity and corrosion resistance along with good thermal endurance but require thermal curing and have short pot lives.  Silicone coatings are also prone to abrasion (low cohesive strength) and have high coefficients of thermal expansion.

Strengths

• Stable Over Wide Temperature Range (in General, -40°C to 200°C) [104°F to 392°F]
• Flexible, Provides Dampening and Impact Protection
• UV/Sunlight Resistance
• Good Moisture and Humidity Resistance
• High Dielectric Strength
• Low Surface Energy (Enables Effective Penetration Under Components)

Weaknesses of Cure Type

Room Temperature Vulcanization (RTV)

• Requires humidity (minimum 20%RH) to cure and only intermittent solvent resistance
• Low abrasion resistance
• Short pot life
• TCE is ~300-350ppm/°C
• If proper house keeping is not followed, there is  a potential for cross contamination

UV Cure

• One-component coatings require accurate application materials to avoid shadowed areas
• Potential for cure inhibition
• Low abrasion resistance
• UV intensity and wavelength affects cure
• Some secondary-cure mechanisms react with moisture, this can cause spray valves to become clogged

Catalyzed (Addition)

• Low abrasion resistance
• Potential for cure inhibition
• Adhesion may be difficult
• Only intermittent solvent resistance
• If proper house keeping is not followed, there is a potential for cross contamination