Looking to better protect your electronic assemblies? Conformal coatings are here to help!
By Brian Chislea, Application Engineer, and Cody Schoener, North America Sr. Marketing Manager, Consumer & Electronics at Dow Electronics.
Protecting sensitive circuit assemblies from the deleterious effects of the environment is crucial to electronics performance and longevity across industries, from automotive and aerospace to consumer devices and home appliances. One of the emerging technologies that can help address these protection concerns is that of conformal coatings.
What are conformal coatings?
Conformal coatings are thin layers of polymeric material applied on top of circuit assemblies to protect the board from dust, dirt, moisture, and other environmental factors. These coatings “conform” to the circuit board, similar to the way in which paint adheres to a surface, offering close protection of the board’s components.
By applying conformal coatings, electronics manufacturers can enhance the durability and reliability of their devices, extending their lifespan and contributing to reduced landfill waste. Conformal coatings also provide excellent thermal and electrical insulation, shock and vibration absorption, and reduced component failure rates. Additionally, when compared to similar dielectric products like encapsulants, conformal coatings only require a thin layer, allowing for protection of electrical components without having to add significant excess weight to the end-product.
Industries where reliability is non-negotiable, such as automotive, aviation, and aerospace, require the use of conformal coatings to add an extra layer of protection to electronics that need to operate flawlessly under challenging conditions, e.g., a braking system on a car or a piloting system within an aircraft. While these industries have long recognized the value of conformal coatings, there is great potential for these materials to offer protection and reliability across a much broader range of electronics.
Types of conformal coatings
Conformal coatings are available in a variety of materials, including legacy acrylics and polyurethanes, silicones, styrene block copolymers and, to a lesser extent, epoxies. Each offers different performance attributes suitable for different applications, however, silicones tend to meet the broadest needs for electronics protection. Silicones can be applied as thin or as thick as needed and can accommodate much higher (and much lower) temperatures than some of their material counterparts. They are a durable material that can help extend the life of products and reduce the rate of failure when compared to other non-silicone based conformal coatings.
Many companies in the electronics industry are looking to reduce or eliminate the use of solvents, and solventless silicone conformal coatings offer the performance they need, along with additional sustainability and cost advantages. Solventless silicone conformal coatings eliminate the harmful emissions associated with solvents, supporting a better working environment for employees on the manufacturing floor.
They also reduce the complexities and added costs around storing and shipping potentially flammable materials, as well as solvent disposal or recapture. This shift toward solventless options supports a safer, more streamlined production process with the same level of protection expected of traditional conformal coatings.
Curing methods for conformal coatings
Just as there are various types of conformal coatings, there are also different methods for curing these coatings, each suited to specific manufacturing needs. Room temperature or moisture cure uses the moisture in the air to cure the coating onto the board—a process that requires a separate space in a manufacturing plant for drying and could take hours to complete. If space and time are not major concerns, moisture cure conformal coatings have the lowest cost of entry.
Many manufacturers today, however, are looking for ways to improve the efficiency of their production lines, which can include a quicker curing method. With heat curing, the conformal coating is applied to the assembly and then put into an oven and baked for a set period at a set temperature, thereby reducing the cure time from hours to minutes. While heat curing helps with efficiency from a timestandpoint, it does require investing in a large piece of equipment, which some manufacturers may not have the space or budget for. Being heat-based, this method of curing also requires considerable energy consumption.
UV curing, on the other hand, is a newer method of curing conformal coatings that is designed to alleviate some of the pain points from traditional methods. With a UV cure, manufacturers do not need to secure a large space to house their production line. Because it utilizes broad spectrum UV or LED light, boards can be cured in less than a minute, further reducing the cure time from that of a heat-based process and doing so with significant energy savings. A lightning quick cure time allows for increased output without the need for extra production lines, helping to improve cost-efficiency while maintaining product quality.
A bright future for conformal coatings Looking towards a future of continued innovation across the electronics landscape, conformal coatings can play a major role in supporting the reliability and durability of circuit assemblies.
Choosing the right conformal coating will be dependent on the specific needs of the manufacturer and the electronics
they are producing, but advancements in UV- cured, solventless silicone conformal coatings, like Dow’s DOWSIL CC-8000 Series UV and Dual Moisture Cure Conformal Coatings, represent a promising development for the industry.
As electronics manufacturers navigate the options available, this subset of conformal coatings provides a compelling solution that not only delivers strong protection and operational benefits, but also aligns with the growing focus on sustainable manufacturing practices.