Called Dowsil CC-8030, it is a one-part product that also includes moisture-cure for the nooks and crannies that UV cannot reach so well.
“Other silicones support UV curing, but none are conformal coatings with a low enough viscosity for spray coating,” claimed Dow. CC-8030 is “industry’s first solvent-less silicone conformal coating with a UV and moisture dual cure system, with rheology that is designed for high-throughput spray coating”.
It is formulated without benzene, toluene, ethylbenzene or xylene (BTEX) solvents, and achieves a viscosity, according to the data sheet, of typically 520cP measured by cone and plate (50rpm).
UV cure is preferably mercury vapour lamp (H-type), and can be across a broad spectrum – UV A, UV B and UV C. With a standard mercury broad spectrum lamp at 300mW/cm2, the coatign will be tack-free after <10s, according to the firm, and it can be applied in multiple layers.
Modulus is low to avoid stressing delicate components, and elongation is said to be high for reliability against stress.
“The new coating’s secondary alkoxy moisture curing reaches any shadowed areas where UV light can’t penetrate, or UV curing is otherwise incomplete. Moisture curing also supports thicker coating and won’t add stress from thermal cycling,” said Dow.
Photo: scanning UV curing probe