SAN DIEGO, Calif. — A new silicone conformal coating from Dow is described by the company as an environmentally progressive coating for protecting rigid printed circuit boards (PCBs), sensitive electronic components, and fine-pitch designs from environments with airborne contaminants. The DOWSIL™ CC-8030 UV and Moisture Dual Cure Conformal Coating is formulated without benzene, toluene, ethylbenzene or xylene (BTEX) solvents. It is the electronics industry’s first solvent-less silicone conformal coating with an ultraviolet (UV) and moisture dual-cure system for high-volume electronics manufacturing, Dow said in a release.
The DOWSIL CC-8030 coating is said to promote sustainability, health, and safety while reducing processing costs through automated spraying and fast, energy-efficient UV curing. Although other silicones support UV curing, none are conformal coatings with a low enough viscosity for spray coating and with a secondary moisture cure for shadowed areas. DOWSIL CC-8030 also offers more reliable protection against stress and thermal cycling versus competitive materials, Dow said in its release.
Brian Chislea, senior electronics application engineer at Dow, discussed the new coating and cure system that protects printed circuit boards from contamination during two sessions at IPC APEX Expo 2020, an electronics conference held in San Diego in February.
“Dow has long been an innovative leader and developer of leading-edge conformal coating technologies that address our customers’ most pressing needs,” Chislea said in the release. “DOWSIL™ CC-8030 Coating is an excellent example of this. By listening closely to our customers, we responded with this first-of-its-kind material that can help electronics manufacturers meet their sustainability and productivity goals, and more.”
The new DOWSIL Conformal Coating has a low modulus for delicate components and high elongation for reliable protection against stress. To provide an even greater level of PCB protection, the coating can be applied in multiple layers. Compared to leading acrylated urethane UV cure coatings, the silicone-based technology provides superior protection against thermal cycling, Dow said.
DOWSIL CC-8030 is a soft, medium-viscosity silicone with a rheology designed for high-throughput spray coating. Its dual cure technology is said to combine speed with completeness of coverage for reduced work-in-process inventory. With UV curing from a standard mercury broad spectrum lamp at 300 mW/cm^2, the DOWSIL coating is tack-free after less than 10 seconds. Compared to thermal ovens that cure in minutes, UV ovens are also smaller and consume less energy, Dow said.
According to Dow, the new coating’s secondary alkoxy moisture curing reaches 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.