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中文In the PCBA (Printed Circuit Board Assembly ) process, Conformal Coating is a common protective material, mainly used to protect the circuit board from the influence of the external environment.So what exactly is the role of Conformal Coating?Why is it so important in PCBA processing?
I. What is conformal coating?
Conformal coating is a specially formulated coating that is mainly applied to the surface of PCBA to form a protective film. Its “three protections” usually refer to moisture-proof, dust-proof, and corrosion-proof. Some high-performance conformal coatings can also provide additional protection such as salt spray protection, anti-static protection, and UV protection.
Common types of conformal coatings include:
- Acrylic resin: fast drying, good weather resistance, suitable for general environment.
- Polyurethane: wear-resistant, solvent-resistant, suitable for industrial equipment.
- Epoxy resin: high hardness, chemical resistance, suitable for harsh environments.
- Silicone: high temperature resistance, good flexibility, suitable for high temperature environment.
II. The main function of using conformal coating in PCBA processing
1. Moisture and water resistant to prevent short circuits
PCBA easily absorbs moisture in a humid environment, causing circuit short circuit, corrosion or reduced insulation performance. Conformal coating can form a dense waterproof film on the surface of PCBA, effectively blocking moisture penetration and avoiding malfunctions caused by moisture.
Applicable scenarios:
- Outdoor equipment (e.g. security cameras, communication base stations)
- Humid environments (e.g. bathroom appliances, marine electronics)
2.Anti-dust and anti-particle to improve circuitstability
Dust, fibres and other tiny particles may adhere to the PCBA, affecting heat dissipation or causing short circuits.Three-proof paint fills the tiny gaps on the circuit board, prevents dust from accumulating and improves the long-term stability of the circuit.
Applicable Scenario:
- Industrial control equipment (such as PLC, inverter)
- Dusty environments (e.g. factories, mining equipment)
3. Anti-corrosion, extend circuit board life
Sulfides and acidic gases (such as SO₂ and HCl) in the air may corrode the metal parts (such as solder joints and copper foil) on the PCBA, causing circuit failure. Conformal coating can isolate these corrosive substances and protect the circuit board from chemical corrosion.
Applicable scenes:
- Chemical industry, metallurgy and other industrial environments
- Automotive electronics (long-term exposure to exhaust fumes)
4.Salt spray proof, suitable for marine environment
In coastal areas or offshore equipment, salt spray can accelerate metal corrosion and cause PCBA failure. Conformal coatings (especially polyurethane or epoxy types) can effectively resist salt spray erosion and extend the life of the equipment.
Applicable Scenarios:
- Marine electronic equipment
- Marine Monitoring Equipment
5. Anti-static, protect sensitive components
Some conformal coatings (such as polyurethane or silicone) have anti-static properties, which can reduce the damage of electrostatic discharge (ESD) to sensitive components (such as chips and sensors).
Applicable Scenarios:
- Precision electronic equipment (e.g. medical instruments, aerospace equipment)
III. Precautions for using conformal coating
- Selective coating: Not all PCBAs require full coverage with conformal coating. Some areas that require heat dissipation or repair (such as heat sinks and test points) may need to be partially exposed.
- Curing conditions: Different types of conformal coatings require different curing methods (natural drying, heating curing, etc.), which must be strictly followed according to the manufacturer’s requirements.
- Compatibility test: Some conformal coatings may not be compatible with components on the PCBA (such as LEDs, capacitors), and testing is required before use.
IV. Conclusion
In PCBA processing, the main role of three-proof paint includes moisture-proof, dust-proof, corrosion-proof, salt spray-proof and anti-static, which can effectively improve the reliability and service life of the circuit board.Choosing the right type of three-proof paint and correct construction can significantly improve the stability of electronic equipment, especially for industrial, outdoor, automotive and other harsh environments.
