How to protect PCB? Complete guide to protecting printed circuit boards
Printed circuit boards, i.e. PCB (Printed Circuit Board), are the foundation of virtually every modern electronic device. They are present in computers, automation systems, automotive electronics, industrial equipment, and IoT devices. Each PCB is responsible for connecting all electronic components and enables the proper operation of the entire system.
At the same time, a PCB is highly sensitive to environmental conditions. Moisture, dust, temperature, and chemicals can cause corrosion of printed circuit boards, deterioration of solderability, and device failures.
Therefore, PCB protection is an extremely important stage in the production and use of electronics. A properly selected PCB protective coating and correct electronic protection methods make it possible to significantly increase device durability.
PCB protection – why is it so important in electronics?
In practice, many electronic failures result from environmental impact. Moisture ingress in PCB boards, contamination, or high temperature can lead to degradation of traces and soldered components.
Therefore, PCB protection is a standard in many industries, such as:
industry,
energy,
automation,
automotive.
A properly selected PCB protective coating protects printed circuit boards against moisture, temperature, and chemicals.
Effective board cleaning and printed circuit board cleaning
Before PCB protection is applied, thorough printed circuit board cleaning is required.
During electronics assembly, the following remain on the PCB surface:
flux residues,
rosin,
production contaminants,
process oils and greases.
Therefore, effective board cleaning is the first step in the electronics protection process.
If you want to learn more about this process, we have described it in detail in a previous article:
Is PCB cleaning necessary? – TermoPasty
Thorough printed circuit board cleaning increases the effectiveness of protective coatings and improves PCB protection.
PCB protection after etching – LT4 flux lacquer
Let’s start from the beginning – what is PCB etching?
PCB etching is a chemical process used in the production of printed circuit boards, involving the removal of excess copper from the surface of the laminate. As a result, conductive traces are formed, which, according to the design, connect individual electronic components.
One of the first stages at which it is worth considering electronics protection is immediately after the etching process. Freshly exposed copper reacts very quickly with air, leading to its oxidation even within a short time.
To prevent this, LT4 flux lacquer is used, which effectively protects printed circuit boards during storage and additionally improves the soldering process. This preparation:
protects copper against oxidation,
increases solder wettability,
enables soldering even of oxidized surfaces.
This solution is particularly commonly used in the production of prototype printed circuit boards.
PCB varnishes and protective coatings – conformal coating
One of the most commonly used methods is PCB protection using varnish.
Specialized varnishes form a thin PCB protective coating that protects electronics against moisture, dust, and chemicals.
Such conformal coatings conform to the shape of components and provide effective protection of the entire assembly.
Are PVB 16 and PVB 60 varnishes effective PCB protective coatings?
Polyvinyl varnishes include PVB 16 and PVB 60. They form a transparent protective coating that effectively protects PCB boards against moisture and contamination.
PVB 16 forms a thin protective layer, ideal for standard applications, whereas PVB 60 provides a thicker and more durable coating, offering enhanced protection of PCB boards in more demanding operating conditions. An additional advantage of both varnishes is the ability to solder without the need to remove the varnish layer, which significantly facilitates service and assembly work.
How to remove protective coatings?
During electronics repair, it may be necessary to remove protective coatings.
In the case of PVB varnishes, a PVB solvent is used, which enables safe removal of the coatings.
Thanks to this, PCB protection does not hinder subsequent servicing of devices.
Silicones – properties of silicone coating
In more demanding applications, silicones are used.
Silicone coatings provide:
flexibility,
moisture resistance,
resistance to variable and high temperatures.
The most important properties of silicone coatings are very good electrical insulation and high resistance to extreme temperatures and environmental factors, which makes them indispensable in the protection of electronic assemblies.
PCB potting – electronics encapsulation
Potting is the highest level of protection.
In this process, the electronics are completely covered with a სპეციal protective compound.
This solution provides:
moisture protection,
vibration resistance,
high mechanical strength.
Encapsulation compounds are used in industrial electronics, electrical engineering, and wherever systems require effective protection against moisture, dust, and the influence of the external environment.
Depending on application requirements, different types of potting compounds are used, including silicone potting compounds, which combine very good insulating properties with resistance to weather conditions and durability across a wide temperature range.
Silicone potting compound 011 is an innovative material curing in a condensation system, applied as a two-component system. The transparent liquid, when mixed with a catalyst, transforms into a clear, solid rubber that precisely encapsulates the protected components. Its properties include:
high dielectric strength,
high volume resistivity,
ability to penetrate even very fine gaps,
formation of a durable, stable, and tight coating.
Thanks to its liquid form before curing, compound 011 reaches every space, ensuring complete encapsulation. After curing, it effectively protects electronic assemblies against moisture, dust, and temperature variations. It is particularly suitable for the encapsulation of components and the protection of power conductors.
Silicone potting compound 019, in turn, is also a two-component material curing in a condensation system, but with a different application profile. Before curing, it is characterized by high viscosity, which limits its penetration through fine openings and allows for effective filling of larger spaces. After curing, it forms:
a hard, milky rubber,
high mechanical resistance,
very good dielectric strength,
an effective barrier against moisture and external factors.
Thanks to these properties, compound 019 is used where mechanical stability and durable protection of components are critical. It is ideally suited for protecting electronic and electrical assemblies operating in demanding environmental conditions.
The selection of an appropriate potting compound therefore depends on the nature of the application – in cases where precise penetration and complete encapsulation are required, 011 will be the better choice, whereas in situations where filling larger spaces and higher mechanical resistance are important, 019 will be more suitable.
PCB storage and PCB warehousing – how to do it correctly?
Proper PCB storage is also very important.
During PCB warehousing, it is necessary to ensure:
humidity control,
protection against dust,
antistatic packaging.
Appropriate PCB storage prevents trace oxidation and increases the durability of electronics.
Selection of PCB protection – how to choose the appropriate method?
A good selection protects printed circuit boards against several factors:
operating environment,
temperature,
humidity,
serviceability.
The most commonly used methods include:
printed circuit board cleaning (alcohol-based PCB cleaner, water-based PCB cleaner, Kontakt PCB Plus, Thermosonik PCB),
LT4 flux lacquer,
PVB 16 and PVB 60 varnishes,
encapsulation compounds (silicone potting compound 011, silicone potting compound 019).
Properly selected PCB protective coatings ensure effective PCB protection in most applications.
Other protective coatings:
Parylene – advanced PCB protective coatings
One of the most advanced technologies for electronics protection is parylene (a thin, transparent polymer coating applied using chemical vapor deposition (CVD)).
This coating is applied in a vacuum process and forms a very thin protective layer with high chemical resistance.
Urethanes – applications of polyurethane coatings
The second group of materials comprises urethanes, i.e., polyurethane coatings, which are modern protective coatings based on polyurethane resins, used to protect surfaces against mechanical, chemical, and atmospheric factors.
Their main advantage is very high chemical resistance.
Therefore, the applications of polyurethane coatings include industrial electronics.
PCB protection – research and practical applications
Research on electronics durability shows that appropriate PCB protection can significantly increase device reliability.
In many industrial applications, electronics protection makes it possible to extend device lifespan even several times over.
Therefore, the use of appropriate PCB protective coatings is now a standard in modern electronics manufacturing.