PCB Conformal Coating Features Fast Tack Free Cure

1st September 2009

ES Admin

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Moisture-curing silicone conformal coatings are ideally suited as protective coatings for sensitive board components in demanding environments. However, electronic manufacturers avoided the use of silicone coatings in electronic packaging due to their long cure schedule that did not allow rapid assembly. Master Bond has developed a rapid tack free, ready-to-use silicone conformal coating called Master Sil 773, formulated to provide excellent protection to electronic circuitry in high humidity environments as well as upon exposure to shock and vibration. It cures quickly at ambient temperatures to a highly flexible, transparent, low hardness silicone coating. Adhesion to critical board components is outstanding.

A most useful characteristic of this product is that it maintains its low modulus over the remarkably wide temperature range of -65°C to in excess of +200°C. This one part, ultra low viscosity silicone adhesive is ideal for application as a low stress coating affording optimal protection to sensitive board components in demanding environments. Master Sil 773 is 100% reactive and cures by the moisture mechanism. If needed, a UV tracer dye is also available with this system.
The Master Sil 773 silicone conformal coating can be applied by dipping, spraying, brushing. It is suitable for either manual or highly automatic coating techniques as its tack free time is less than 5 minutes. These cured silicone conformal coatings are very easy to repair. No solvents are required for either application or repair procedures. Its electrical performance is exceptional with volume resistivity of 1x1014 ohm-cm, dielectric strength of 25 KV /mm, a dielectric constant of 3.3, 60Hz and a dissipation factor of 1x10-4.