As consumers pay more and more attention to the quality and reliability of products, electronic products are more intelligent and lightweight, which puts forward higher requirements for PCBA technology. At the same time, with the deterioration of the ecological environment, some pollutants and dust in the environment begin to corrode PCBA. Therefore, in the past, conformal coatings that were only used for high-grade products such as military products have gradually expanded to ordinary household appliances, small household appliances, LED lamps and other products.
In addition, the rise of emerging industries, charging of electric vehicles, and widespread use of drones have further expanded the use of conformal coatings. At present, the application of conformal coatings in PCBA has become a mainstream trend.This article will introduce about PCB conformal coating.
What is conformal coating on PCBs
Conformal coatings are specially formulated synthetic paints that are mainly used to protect PCB and related equipment from environmental influences, extend their service life, and ensure that they work safely and stably.
Conformal coating ensures the integrity of components through electrical insulation, as well as protects printed circuits board from air pollutants and harsh environments.
These coatings applied on PCB board to form a film (25 – 50 μm) that protects circuits from chemicals (e.g. fuels, coolants, etc.), vibration, moisture, salt spray, moisture and high temperatures. These hazards can cause uncoated PCB boards to corrode, mold or leak electricity, which can lead to failure. The conformal coatings improves the reliability and safety of printed circuit boards and extends the life of printed circuit boards.
What are the types of conformal coating
● Acrylic paint
Acrylic paint has good flexibility. It can provide all-round protection and is easy to use and remove.
● Silicone
There are two types of silicone conformal coatings: solvent-resistant and solvent-removable. They are all high-temperature curing and have excellent resistance to chemicals and salt spray. Solvent-resistant products can be welded, but they are difficult to remove. Silicone conformal coatings have excellent insulation, making them ideal protective materials for high-power or high-density circuit boards.
● Polyurethane
These coatings are available in both one-component and two-component systems. The most common are one-component systems. It has good moisture resistance, chemical resistance, and at the same time has good electrical properties. But once cured, it is difficult to remove.
● UV-curable type
This is a coating that uses ultraviolet energy to cure and is insoluble in solvents. This means that they are non-flammable and do not contain VOCs in the paint, fully meeting current environmental laws. This coating has high chemical and heat resistance, good flexibility and gloss, and excellent adhesion and surface leveling.
● Water-based coatings
Waterborne coatings are harmless, but because water evaporates more slowly, it requires longer drying times and higher curing temperatures (900C). Because water is the only diluent in the system, it does not contain VOCs, but contains many different chemicals.
● Fluorine-modified acrylic
Acrylic paints resist any moisture. It forms an extremely thin coating that shields the part. This film can be easily removed mechanically.
What is the advantage of conformal coating
► Provide comprehensive protection: the conformal coating on the surface of the circuit board can prevent moisture, dust, high and low temperature resistance and pollutants,which would protect the circuit surface from a variety of solvents and chemicals erosion.
► Improve dielectric properties: the circuit board is corrosion-proof after coating with three-proof paint, and it is not easy to soften and deform, because the three-proof paint plays a mechanical support role on the components on the board, prolonging the fatigue life of the solder joint. The board spacing of the circuit board is reduced, which can achieve the purpose of component miniaturization. In addition, conformal coatings significantly reduce the risk of short circuits caused by whiskers of adjacent conductors.
► Simple operation process: circuit board three-proof paint can be sprayed, dipped or brushed on the surface of the circuit board to form a layer of film, providing reliable protection for various circuit board substrates such as rigid plates, flexible materials, metals, glass and plastics. The operation process of conformal paint is simple, if the thickness of the film layer is required, the ideal thickness can be obtained by increasing the number of coatings.
► Less time-consuming and low cost: the use of conformal paint can reduce the weight of the circuit board and reduce unnecessary covering objects and shells. In addition, for manufacturers, reducing board repair rates means shorter production times and less labor, directly reducing costs.
► Protect confidential information: Some conformal coatings are specially made black to cover and protect the marks, labels, identification marks and confidential information on the circuit board, so that the circuit board has a high degree of confidentiality.
How is conformal coating applied
1. Brushing. It use a brush to apply the covering to the circuit board. The advantage of using this method is that it may be more suitable for small areas. It can produce excellent coating effect on smooth surfaces.
2. Spraying. The use of spray can type products can be convenient and directly used, more suitable for straight plug-in more circuit boards, avoid brushing with brushes out of place, the operation process is simpler.
3. Dip coating. Dip coating can ensure complete coating, which is more suitable for use on circuit boards without terminal blocks.
Can conformal coating be removed
Yes. When a circuit board coated with conformal coating needs to be repaired, the original coating needs to be removed first. There are mainly the following 4 ways to remove:
● Thermal removal
The conformal coating is burned at high temperature using an electric soldering iron. However, this method can have a range of adverse effects, such as PCB discoloration, residues, damage to solder joints and components, or the production of toxic gases.
● Chemical removal
The coating is removed by dissolving the solvent and is easy, safe and does not damage the component.
● Mechanical removal
Use a tool such as a knife or sandpaper to sand to remove the coating. However, because the coating is strong, excessive force during this process can damage the board substrate.
● Micro sandblasting removal
Powered by compressed air, the abrasive is sprayed onto the surface of the part to be removed quickly and efficiently.
Top 15 PCB conformal coating manufacturers
1. CSL Silicones
Website: https://www.cslsilicones.com/en/
With 30 years of experience in the manufacture of Room Temperature Vulcanizing (RTV) silicone products, CSL Silicones Inc. has two product areas of focus with the following application industries:Protective Coatings: Anti-Graffiti, Anti-Corrosion, High Voltage Insulator Coatings,; Silicone Sealants:Building & Construction, Electronics & Electrical, Manufacturing & Industrial, Transporation, Energy, Assets & Infrastructure
2. Dymax Corporation
Website: https://dymax.com/about-dymax/our-company
Dymax Corporation was originally founded in 1980 as the American Chemical and Engineering Company. Forty years later Dymax is a leading developer of innovative rapid and light-curable materials, dispense equipment, and UV/LED light-curing systems.
3. DOW Corning
Website:https://www.dow.com/en-us
Dow Corning Corporation was an American multinational corporation headquartered in Midland, Michigan, United States. Originally established as a joint venture between After a brief existence as a DowDuPont-owned company, as Dow spun out from DowDuPont on April 1, 2019, it is now a new company, Dow Silicones Corporation, which is wholly owned by Dow and specializes in silicone and silicon-based technology, and is the largest silicone product producer in the world.
4. Europlasma NV
Website:https://www.europlasma.net/
Europlasma is a global technology leader in innovative nano-coating solutions based on low pressure plasma technology, for which it develops proprietary processes, designs and builds turnkey vacuum plasma treatment equipment and supplies process chemicals.
5. Chemtronics
Website:https://www.chemtronics.com/
Chemtronics is the industry leader in solutions for the electronics, telecommunications, and critical environments markets. The company aims to meet all cleaning, coating, and maintenance needs.
6. Cytec Solvay
Website:https://www.solvay.com/en/
As a global leader in Materials, Chemicals and Solutions, Solvay brings advancements in planes, cars, batteries, smart and medical devices, water and air treatment, to solve critical industrial, social and environmental challenges.
7. Kisco
Website:https://www.kisco.co/
The Kyung-In Synthetic Company (KISCO) develops and manufactures chemicals. For over 50 years the KISCO group of companies has been producing dyes, inks, fine chemicals and materials for textiles, food, agriculture and electronics.
8. MG Chemicals
Website:https://www.mgchemicals.com/
Founded in 1955, M.G. Chemicals is a manufacturer and wholesaler of chemical products for the electronics industry. Their chemical products include dusters and circuit coolers, cleaner / degreasers, flux removers, contact cleaners, protective coatings, solder, epoxies, adhesives, RTV silicones, lubricants, EMI/RFI shielding coatings, thermal management products, prototyping supplies, and more.
9. HB. Fuller
Website:https://www.hbfuller.com/en/north-america/
H.B. Fuller Company is a major American adhesives manufacturing company supplying industrial adhesives worldwide.
10. ELANTAS Electrical Insulation
Website:https://www.elantas.com/
ELANTAS is a leading manufacturer of insulating and protective materials with focus on the global electrical and electronics industry.
11. Hernon
Website:https://www.hernon.com/
Hernon Manufacturing Inc. is a company that specializes in the production of adhesives, sealants, coatings, and dispensing equipment. It is a leading provider of high-performance materials for a wide range of industries, including aerospace, electronics, automotive, and more.
12. ACC Silicones
Website:https://cht-silicones.com/
CHT further strengthened its position as a global producer of speciality silicone elastomers and rubber with the acquisition of the ICM silicones Group in 2017 which included Quantum Silicones, ACC Silicones, ICM Products, Amber Silicones and Treco SRL.
13. Electrolube
Website:https://electrolube.com/
Electrolube, a brand of MacDermid Alpha Electronics Solutions, have been developing solutions to advance engineering and enhance technological performance, since 1941.
14. Henkel
Website:https://www.henkel.com/
Henkel holds leading positions in both industrial and consumer businesses: portfolio includes well-known hair care products, laundry detergents, fabric softeners as well as adhesives, sealants, and functional coatings.
15.chase corporation
Website:https://chasecorp.com/
Founded in 1946 , chase corporation has grown to become a global specialty chemicals company that is a leading manufacturer of protective materials for high-reliability applications across diverse market sectors.
Conclusion
In recent years, PCB Conformal coatings often play an important role in protecting medical, electronics, protection, aerospace, LED and automotive applications. The circuit board conformal coating has three anti-effects such as moisture-proof, salt-proof, anti-static electricity, etc., and also has the properties of thermal shock resistance, anti-aging, radiation, ozone corrosion, vibration, flexibility, adhesion and so on.
Conformal coatings are specially formulated synthetic paints that are mainly used to protect PCB and related equipment from environmental influences, extend their service life, and ensure that they work safely and stably.
Acrylic paint
Silicone
Polyurethane
UV-curable type
Water-based coatings
Fluorine-modified acrylic
Yes. When a circuit board coated with conformal coating needs to be repaired, the original coating needs to be removed first.
