Heat Cure Coating / Evaporation Cure Coating
Solvent based coatings cure by evaporation of solvents, this process can be accelerated in most cases by using heat, however this can affect the properties of the coating and cause coating defects if not performed correctly. In the case of Electrolube’s DCA for example, if you heat cure you get additional chemical resistance and greatly improved properties. Without heat cure, it offers good humidity protection. AFA, a non cross-linking solvent-based acrylic on the other hand, will reach the same protective capability regardless of the curing conditions, the use of heat just accelerates the process.
UV Cure Conformal Coating
UV curing uses intense ultraviolet light to set off a chemical reaction within the coating in order to cure almost immediately in areas exposed to the UV radiation. Due to the 3-D nature of most assemblies there will nearly always be areas that remain unexposed to the UV radiation (e.g. beneath components) and therefore a secondary cure mechanism is required. Moisture is the most common secondary initiation process since it does not require an additional process step, however formulations are available that use heat, although the cure times are relatively long (30 mins or more), and the temperatures are quite high (>120°C) which places additional thermal fatigue on the assembly.
Electrolube also offer UV cure coatings such as UVCLP and UVCLX which have a reliable chemical cure mechanism as the secondary process. This is considerably faster than the industry standard, with a full cure guaranteed in just 6-12 hours compared to up to two weeks or more with some products.
UV curing materials are popular in high throughput environments, since in most cases the parts can continue through the process within seconds of the curing process, thus speeding up manufacturing velocity and reducing Work In Progress (WIP).
Moisture Cure Coatings
Moisture cure coatings require moisture from the atmosphere to cure. The humidity in the atmosphere can affect the speed of cure; increasing the humidity will often speed up the process. Humidifiers can be added to conventional and IR ovens to provide greater humidity and accelerate this process. It is important that these products are handled with care. If containers are left open for long periods of time then moisture will be absorbed and the coating will begin to cure.
In the case of dip coating a dry argon blanket can be passed over the surface of the tank to ensure that the coating is kept dry whilst processing
