Solvent-less, dual-cure conformal coatings from Dow

The CC-8000 series, as it will be known, are dual-cure silicones where ultra-violet exposure gives a fast initial cure to ‘grab’ any loose parts, while exposure to moisture gradually cures areas from which the UV was obscured.

“The ability to cure in seconds with broad spectrum UV or LED light allows for high production throughput and reduced energy costs when compared with heat-cure materials, and time compared to room-temperature cure materials,” according to Dow.

A needle-deposited rectangular wall of CC-8036 acts as a dam for the sprayed CC-8033 infill. UV accompanying the spray head cures it all

Variants within the range offer a variety of viscosities and application methods:

CC-8030 is low viscosity, for manual spraying, automated spraying, flowing or jetting – for example when coatings need to flow through vias or under ICs.

CC-8033 is medium viscosity for needle dispensing for damming, keep out regions, or when thicker coating protection is required.

CC-8036 is high viscosity for needle dispensing and increased control over the speed and distance of flow. It also produces the thickest coating in one pass.

Preferred light-base curing is using an ‘H’ bulb or 365nm LED. 2J/cm² will cure over 3mm of thickness.

Secondary moisture curing takes between 48 and 72hr to make the coating tack-free.

Once cured, operation is over -40 to 150°C for long periods, although “at both the low and high temperature ends of the spectrum, behavior of the materials and performance in particular applications can become more complex and require additional considerations”, said Dow.

As an example, find the mid-viscosity CC-8033 on this product page