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Coating Spotlight: SCS Polyurethane Conformal Coatings
Polyurethane conformal coatings provide excellent moisture and chemical protection and are commonly used in the electronics, defense and aerospace industries. Polyurethanes are available in single-part or two-part coatings. Two-part polyurethanes require Part A and Part B to be mixed at a predetermined ratio for proper application and curing. While there are numerous formulations available, a few well known polyurethane coatings include HumiSeal® 1A33, HumiSeal 1A20, ARATHANE® 5750 and CONATHANE® CE-1155.
Similar to other conformal coatings (e.g. acrylics, epoxies, silicones, etc.), polyurethanes are applied via manual or automated spray, brush or dip methods. Two-part polyurethane coatings can be challenging to apply using automated spray due to their additional mixing requirements; as a result, many two-part polyurethanes are manually sprayed or brushed onto applications.
Polyurethane coatings offer many beneficial properties, including robust protection against chemical exposure and solvents, moisture protection and abrasion resistance. Additionally, there are low outgassing polyurethane coatings available that can be used in space applications.
While polyurethanes have many advantages, the coatings also have a few drawbacks to take into consideration. For example, polyurethanes can be difficult to remove or rework due to their strong solvent resistance properties. If rework of components is a concern, acrylic conformal coatings might be a better fit. Additionally, polyurethanes have relatively long cure times with many common formulations requiring 20-30 hours for curing. After the coating cures, it normally turns an amber color, making it unsuitable for LEDs.
Polyurethane conformal coatings offer tough, reliable protection against moisture and chemical solvents for electronics and printed circuit boards. To learn more about polyurethane conformal coatings and how they can protect your applications, contact Sean Horn at 814.535.3505, ext. 1802, or shorn@scscoatings.com.
Global Coverage Issue 93, Fall 2022
