Conformal coating defends assemblies from moisture

Intertronics' sales partner Dymax Corp has trialled its Dual-Cure 9481 Conformal Coating, showing significant improvements over previously available products.

Dual-Cure 9481 is a new coating that represents what the company claims as an advance in light/moisture cure technology.

The product is specifically formulated to ensure complete cure in coating applications where shadowed areas on high-density circuit boards are a concern.

Previously, areas shadowed from light were managed by selective coating - eliminating the need to cure in shadowed areas - or a secondary heat cure process.

Users needed to balance the cost of selective dispensing equipment and time/energy costs of a secondary heat cure.

With Dual-Cure 9481 Conformal Coating, shadowed areas cure over time with moisture, eliminating the need for that second process step or concerns of component life degradation due to temperature exposure.

In addition, Dual-Cure 9481 fluoresces bright blue when exposed to UV light and is low viscosity, allowing it to be dispensed easily.

Dymax has conducted extensive laboratory, as well as field testing of Dual-Cure 9481, which is now available from Intertronics in the UK.

The results indicate substantial progress in addressing those challenges typically associated with conventional dual-cure materials.

Dual-Cure 9481 is formulated to address high-volume production and field trials have resulted in very favourable response from a variety of pcb assemblers.

Historically, light-cured conformal coatings have been most successful in applications with no or minimal shadowing.

Shadow areas, which can inhibit the access of light, have the potential to hold or trap the conformal coating and limit the full cure of the materials.

In recent years, several companies have made attempts to commercialise conformal coatings which address the need for shadow curing with conventional moisture curing as a secondary cure mechanism.

Most of these attempts have had limits related to the efficiency of the cure as well as the consistency of the final properties.

Other challenges have included special packaging and handling requirements, as well as objectionable odours - substantially now dealt with in Dual-Cure 9481.