In the world of electronics, durability and reliability of components are of paramount importance. This concept is especially true in harsh environments where dust, humidity, chemicals, and temperature changes can compromise the performance and longevity of devices. That is why conformal coating plays a decisive role in protecting printed circuit boards (PCBs) and other electronic components, providing a durable barrier against a wide range of environmental threats.
What is conformal coating?
A protective paint or conformal coating is a thin polymer film applied to a printed circuit board (PCB) for the purpose of protecting the board and its components from the environment and preventing corrosion. The film is generally applied in thicknesses of 25-250 µm and “conforms” to the shape of the board and its components. It is designed to cover and protect solder joints, electronic components, exposed traces, and other metallized areas from corrosion and external agents, ultimately extending the life of the PCB.
There are several types of materials used for conformal coating, including silicone, acrylic, polyurethane and epoxy materials. The choice of material depends on the specific protection requirements, the application process, and the operating environment of the device.
The application of conformal coating is particularly important in industries, such aselectronics, automotive or even aerospace, where devices are often exposed to critical and unpredictable environmental conditions. Conformal coating can be applied in various ways, through dipping, spraying or even brushing. Each method has its own advantages according to the specific application.
The advantages of conformal coating
A newly manufactured circuit board will work well, but performance can rapidly deteriorate due to external factors in its operating environment such as moisture, chemicals, saline environment, and extreme temperatures.
A protective paint can be used in such environments to protect circuit boards and their components and ultimately prevent corrosion and failure. The protection provided enables designers to meet miniaturization and reliability requirements.
Below are some of the main advantages of conformal coating in protecting printed circuit boards (PCBs) and electronic components:
- Protection against moisture and condensation: creates an impermeable barrier that protects components from corrosion and short circuits caused by moisture;
- Resistance to chemicals: provides protection against solvents, salts, acids and alkalis in the operating environment, which might otherwise corrode or degrade them;
- Dust and debris protection: prevents the accumulation of dust and debris on components, which can cause electrical or thermal failure;
- Electrical insulation: improves electrical performance by insulating components from accidental short circuits due to contamination or condensation;
- Increased operational life: by providing comprehensive protection against a range of environmental threats, conformal coating significantly extends the useful life of electronic devices;
- Reduced maintenance and warranty costs: by improving reliability and reducing the failure rate of devices, conformal coating can lead to reduced costs associated with maintenance, repairs, and warranty replacements.
These advantages make conformal coating an important choice for improving the protection and reliability of electronic components in many industries.
Conformal coating: all types
Conformal coatings can be classified according to their basic chemistry; each option has its own beneficial properties for the different environments in which the PCB will need to operate.
The types of conformal coating are:
- Conformal acrylic coating
- Conformal polyurethane coating
- Hybrid conformal coating
- Conformal silicone coating
- Water-based conformal coating
- UV-cured conformal coating
- Conformal coating 2K
The most widely used materials have historically been solvent-based materials, the advantages of which include:
- Ease of processing and application
- Simple viscosity adjustment
- Adaptability to a range of application methods
- Custom application and curing
Conformal acrylic coating
Acrylic paints combine reasonable price with good environmental protection; they maintain transparency and resist browning and hydrolysis under prolonged outdoor exposure. However, they have limited solvent resistance, making them suitable for rework but not for applications where chemical resistance is important.
- They offer excellent protection from moisture and salt spray
- They are easy to apply and remove and dry quickly at room temperature due to simple solvent evaporation
- They have a good range of operating temperatures
- They have excellent adhesion to a wide variety of substrates
Conformal polyurethane coating
Unlike acrylics, polyurethane Conformal coatings offer excellent chemical resistance and superior protection in harsh environments. They maintain flexibility even at very low temperatures. Like acrylics, they are also very versatile and cover a wide range of operating temperatures.
- Good flexibility, especially at low temperatures
- Excellent chemical resistance
- Polyurethane coatings can be removed with specific products
- Excellent resistance to abrasion
Hybrid conformal coating
Hybrid coatings are those in which a mixture of basic chemicals is used. These can result in a number of different coating options to meet the requirements of specific applications.
The range of conformal coatings usually consists of acrylic or polyurethane base resins modified with silicone to improve the resin’s properties at high temperatures. These coatings have a wide range of advantages over standard materials, and because they are solvent-based, they also offer all the advantages of ease of application.
- Extremely wide operating temperature range
- Easy to apply
- High chemical resistance
- Can be reworked with specific products
- Good protection in a wide range of environments
Conformal silicone coating
In general, silicones are the conformal coatings most resistant to high/low temperatures or thermal fluctuations due to their more flexible nature. These coatings offer a wide range of protection in harsh and rapidly changing temperature environments. However, they are less resistant to moisture and corrosive gases than other coating technologies.
- Good all-round protection
- Flexible
- Wide operating temperature ranges
- Normally approved by many industry standards (e.g., IEC 61086, IPC-CC-830, MIL, UL)
- Ease of processing and rework
Water-based conformal coating
Water-based conformal coatings cure by evaporation of water from the system. They are low-VOC options, as they replace most of the solvent in the system with water. This improves operator safety and dramatically reduces solvent emissions.
- Reduced solvent use; improved operator and environmental safety
- Safe products
- Can be applied with standard equipment; immersion and spray versions are available
- They can offer a good level of chemical resistance
UV-cured conformal coating
UV-cured conformal coatings are also another example of hybrid coatings. In this case, different types of chemistry are often used to produce a dual-cure system, thus avoiding problems of areas obscured by UV light during curing. UV-cured coatings offer the fastest cure times, with coatings curing in seconds under UV light. This is extremely beneficial for high-throughput applications, and shaded areas will cure with the secondary curing system over time.
- Due to their highly cross-linked structure, once cured, they can be difficult to remove but offer excellent chemical resistance.
- Extremely fast process times
- Secondary moisture curing system used to promote shadow curing
- Good protection in a range of environments
- Excellent chemical resistance
Two-component conformal coating (2K)
2K two-component conformal coatings are hybrid technologies that combine the best properties of encapsulating resins with those of a conformal coating. These materials offer some of the best protection available, while maintaining the workability and cost-effectiveness of a conformal coating (compared to a resin).
- High performance
- High levels of protection in a wide range of environments
- Thicker application than single-component coatings
- Excellent chemical and moisture protection
Mascherpa’s solutions
Mascherpa is the leading supplier of materials for the electronic component assembly and protection industry. Our advanced DOWSIL and ELECTROLUBE solutions. include a range of products such as encapsulation resins, conformal coatings for electronic board protection, electromagnetic interference (EMI) shielding coatings, thermal dissipation materials, and adhesives and sealants for component assembly and attachment, which facilitate electrical interconnection, provide structural integrity, offer protection from external agents, and transfer heat for increasingly reliable performance. We are proud to distribute products that improve today’s electronic technologies and enable tomorrow’s advances.
Mascherpa’s product range includes a wide variety of solutions such as.
acrylic, silicone, polyurethane, epoxy and hybrid. These include environmentally friendly options, with or without solvent, with curing at room temperature, by heat or by UV light.
