Viscosity control for conformal coating

Paul Boughton

Conformal coating applications present challenges to manufacturers. They must be applied with accuracy, repeatability and selectivity to increasingly smaller packages.

Numerous types of conformal coatings are used to protect sensitive electronic circuitry from harsh environments in automotive, commercial, avionics, military and medical markets.

A key to better process control for conformal coating is a Viscosity Control System (VCS). Certain factors like ambient temperature changes and different material lots can cause viscosity fluctuations which affect the performance and consistency of coatings applied to printed circuit board assemblies.

A VCS combines a heated, recirculating fluid circuit with close-range temperature monitoring to keep the coating process consistent and stable. When a user loads a new batch of fluid in a coating system, the VCS brings the fluid up to optimal coating temperature. Fluid is continuously recirculated past strategically located temperature probes that control the temperature to within 1¢ªC. With consistent conformal coating delivery, solvent usage may be reduced, resulting in less volatile organic compound (VOC) emissions. Conformal coating equipment using components that meet the most stringent standards for use around volatile materials, will ensure safety of the system.

A Viscosity Control System can be found as an option on some conformal coating platforms.

Asymtek is based in Carlsbad, CA, USA. www.asymtek.com

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