Manufacturing electronics involves more than simply design and manufacture. Making sure the board as well as electronic components is safe is a crucial aspect of PCB as well as electronics production. Electronics are now subjected to a variety of environmental factors as a consequence of advances in technology. Also, during the course of their lives, electronic components become susceptible to chemical and mechanical damage.
The functioning and reliability of components might be harmed by hazardous environmental circumstance. Conformal coating thickness has therefore proved a durable remedy for the harm brought on by different environmental dangers. For the conformal coating to be used in the PCB business, it is essential to comprehend its fundamentals. In order to learn more about conformal coating, this article aims to expand its knowledge base.
What Does Conformal Coating Thickness Entail?
A circuit board, as well as its parts, is shielded from chemical deterioration by conformal coating. The polymeric thin layer is also included in the coating to shield a PCB board from outside impurities. The coating is often applied to a PCB’s surface.
Conformal coating also provides defense against contaminates including chemicals and moisture, as well as adverse environmental conditions. Moreover, this covering shields conductors from corrosion and short circuits. It provides insulation to reduce the mechanical and heat stress on electrical components. In the production of PCBs, conformal coatings remain essential, and they are utilized extensively in many different sectors.
Conformal Coating Types
There are several forms of conformal coating.
Urethane coating
High-solvent resistance is provided by this kind of coating. This is also a form of hard coating with high-strength. Urethane coatings offer superior chemical resistance as well as enhanced dielectric resistance. Moreover, polyurethane coating has a low-moisture permeability. Moreover, it resists abrasion.
Yet, this coat type has some disadvantages of its own. In high-temperature conditions, urethane resins do not really function very well.
Conformal coating of silicone
Silicone coatings remain clear and supple. They also offer excellent resistance to corrosion and dampness. Similar to urethane, silicone coatings are resistant to moisture. They are very resistant to heat stress. Silicone conformal coatings also function effectively in high temperatures. They have qualities that allow for light transmission. The dielectric resistance of silicone conformal coatings is not very great.
Acrylic coating
Solvent-based makes up this coating. Furthermore, acrylic resin covering has anti-fungal characteristics. Transparent, resilient, and hard describe this conformal coating type. Because acrylic is soluble inside a variety of different organic solvents, it is possible to restore acrylic coatings. Moreover, acrylic coatings have quick-drying qualities. Circuit boards, however, do not receive sufficient stress alleviation from it.
Conformal covering made of epoxy
Hard conformal coating describes this kind. Epoxy coatings are resistant to the damaging effects of solvents and moisture. They serve as 2 different thermoset combinations.
Due to its resilience against abrasion, chemicals, and moisture, epoxy resin coatings have been frequently employed. However, removing this covering without damaging the pcb board is challenging. This is due to a thermoset mixture shrinking during curing phase.
Paraxylene coating
Crystalline and linear polymer covering is present in proxylene. Materials for conformal coatings are these polymers. This particular conformal coating has high degree of transparency. Moreover, it may fit through small gaps.
What is the Significance of PCB Conformal Coating Thickness
Electronic items run at their highest efficiency thanks to the conformal coating thickness. Moreover, this coating provides the following advantages:
Decreased expenses for upkeep and replacement
The PCBs are protected with conformal coating. As a result, it lessens the harm done to circuit boards. As a result, pcbs require less replacement or maintenance. Also, more money and time may be saved by lowering the likelihood of damage. This happens because a little maintenance will be required.
Risk avoidance
When subjected to certain environmental factors, circuit boards can become damaged in a number of ways. Circuit boards are shielded from such harm by conformal coating, which is its major goal. As a result, conformal coating thickness shields boards from possible environmental risks such as heat and moisture. PCBs are also protected from dust, residues, and other pollutants by conformal coatings.
Improved inspection
UV coating as well as tracers are also part of conformal coating. Through the use of ultraviolet light sources, such UV tracers aid in coating evaluation. The light aids in detecting any flaking, cracks, or foreign objects inside the coatings.
Extreme thinness
Circuit boards and other gadgets have thickness and weight restrictions. There are several advantages to conformal coating thickness . This happens because it can fit properly on PCBs as well as devices that meet the most stringent requirements.
Process of Conformal Coating
The process of producing conformal coating entails a number of processes.
Cleaning
The conformal coating procedure begins with this stage. Cleaning aids in getting rid of various residues left behind from operator handling and soldering. Moreover, it eliminates contaminant-related residues. At this stage, cleaning methods include aqueous chemistry, solvent cleaning, and plasma cleaning.
Priming
A PCB is primed by having a preliminary coating called primer applied to it. This process aids in the creation of layers that will bond the coating and absorb it. The need for priming depends on the resin type.
Masking
In components as well as certain board locations, masking prevents conformal coating from being applied. The PCB needs to have some uncoated spots. So, choosing the appropriate materials is essential to preventing masking failures.
Application
Conformal coatings are applied at this process using a variety of application techniques. These techniques range from dipping to brushing.
Mask removal and completion
Masking must be removed after coating application. De-masking gets followed by finishing. Moreover, finishing aids in avoiding coating flaws and disguising leaks. Moreover, it validates standards and ensures coating quality.
Curing and drying
The circuit board’s coating is confirmed during drying, and it is then prepared for handling by operators. Moreover, this procedure might take a few seconds to many days.
Curing aids in ensuring that the coating acquires the required characteristics and protects the PCB while in use.
The most important phase in conformal coating is inspection. This process involves human examination, AOI, and UV light visibility.
Conformal Coating Certifications and Rules
Conformal coatings must adhere to certain laws and regulations.
UL746E
Consumer electronics safety is governed by the Underwriters Laboratories, a safety certification agency. This UL746E test examines the covered electronics for electrical and fire safety. This PCB is registered with UL under such a particular number when the conformal coating satisfies this test. Each PCB with an authorized coating must also be retested every year to keep its registration.
IPC-CC-83OB
Prior to becoming a civilian standard, IPC-CC-83OB is an IPC conformal coating thickness was a known military standard. This test primarily examines a coating’s appearance, flammability, and stability. Materials that satisfy the MIL-I-46058C standard would also satisfy the IPC-CC-830B criteria. The IPC-CC-830B is also updated often.
IEC 61086
Based upon supplier self-certification, this standard operates. IPC conformal coating thickness on circuit boards are governed by the IEC.
UL94V0
The conformal coating thickness on FR4 is examined for its flammability and self-extinguishing properties. The V-0 classification is the highest you can get. Nevertheless, there are more classifications, such as V-1 and V-2.
For environment protection, conformal coatings should adhere to strict legal requirements. Regulations for conformal coatings are established by the OSHA in the U.S.
Key Factors to Consider While Choosing the Most Appropriate Conformal Coating Thickness for PCBs
Operational Conditions
A PCB can benefit from conformal coating to prevent corrosion in whatsoever form. Thus, it is vital to take into account the coating’s capacity to shield the Circuit board from its surroundings. The temperature range as well as the PCB environment’s humidity must thus be taken into account.
The coating must also be suitable for usage in particular operational circumstances. Calculating the amount of daily exposure is crucial.
Electrical specifications
Typically, this insulating layer is produced using conformal coating. As a result, the most often examined electrical parameter remains surface insulation resistivity. Also, it’s crucial to take that measurement prior to as well as following coating. The coating should thus provide the necessary amount of insulation. The coating must also have a high dielectric strength.
Volume of production
The kind of coating used will depend on the manufacturing volume. Other elements, like as cure times as well as application technique, will be impacted by the manufacturing volume. For instance, any automated applications are better suited for mass manufacturing. Nonetheless, lower manufacturing volumes would be appropriate for hand spray painting.
Components which don’t require coating should be taken into account during PCB design. When preventing interaction with such locations, you can use a selective coating technique. The closeness of these components must also be taken into account.
Conclusion
In the production of PCBs and electronic components, conformal coating thickness is essential. It is among the greatest methods for creating robust and dependable PCBs. Moreover, this coating has superior electrical as well as mechanical qualities. As a result, the conformal coating thickness typically ranges from 1 – 5 mils. When selecting a conformal coating thickness, be sure to take key things into account.
