Secondary Moisture Cure in Conformal Coating Applications

Dual-Cure Conformal Coatings

Conformal coatings enhance the long-term reliability of electronic parts. When applied to circuitry on printed circuit boards they act as protection against destructive environmental conditions, that if left uncoated, could result in a complete failure of electronic systems. High-density PCBs and high-profile components on boards can create shadow areas, and it can be difficult to fully cure a coating that has flowed into these hard-to-reach zones.

In the case of light-curable (acrylate urethane) conformal coatings, areas shadowed from light were traditionally managed by selective coating – eliminating the need to cure in shadow areas – or with a secondary heat-cure process. Dual-cure light/moisture-cure conformal coatings are formulated to cure upon exposure to light first and then with secondary moisture over time. This secondary curing method ensures the material is fully cured, eliminates the need for a second process step, and removes concerns of component life degradation due to temperature exposure if using a heat cure. 

UV Light-Curing of a Conformal Coated Printed Circuit Board


Conformal coatings range from light curable (acrylate urethane) and silicone to parylene and epoxy-based materials. Along with slower curing and processing times, many of these formulations are solvated so manufacturers need to consider the safe disposal of leftover material, and many are looking for a “green” alternative.

Dymax dual-cure light/moisture cure conformal coatings are RoHS compliant, have no solvents added, and cure in seconds upon exposure to broad-spectrum or LED light. Rapid “on-demand” tack-free cure allows coated parts to be instantly processed. Coated PCBs can proceed to the next manufacturing step immediately after light cure and not hold up production while the moisture cure progresses. These materials also meet important testing standards including UL 94 V-0 Flammability and MIL-I-46058C.

These features make Dymax dual-cure coatings ideal for users interested in utilizing more environmentally friendly products, increasing throughput, decreasing work in progress, and achieving greater manufacturing efficiency and cost savings.

Want to learn more? A technical bulletin illustrates the moisture-cure process of a Dymax conformal coating over 7 days. Select the Bulletin: Dual-Cure Light/Moisture-Cure Conformal Coatings in the Resources area to unlock the full details of the document.

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