PCB Tech - Circuit board conformal coating

Circuit board conformal coating is a thin polymer film applied to printed circuit boards (PCBs) to protect circuit boards and their components from the environment and corrosion. This thin film is typically applied to 25-250 µ m, conforming to the shape of circuit boards and their components, covering and protecting solder joints, electronic component leads, exposed marks, and other metalized areas from corrosion, ultimately extending the working life of PCBs.

Due to external factors in its working environment, performance may rapidly deteriorate. Circuit board conformal coating can be used in various environments to protect printed circuit boards from moisture, salt spray, chemicals, and extreme temperatures, to prevent corrosion, mold growth, and electrical failures. The protection provided by conformal coatings allows for higher voltage gradients and smaller rail spacing, enabling designers to meet the requirements of miniaturization and reliability.

What are the types of circuit board conformal coating?

Circuit board conformal coating, also known as PCB electronic circuit board protective oil, coating oil, moisture-proof paint, waterproof glue, insulation paint, anti-corrosion paint, salt spray paint, dust-proof paint, protective paint, coating paint, etc.

Its classification is as follows:

Conformal coating can be divided into acrylic ester, silicone, and polyurethane based on their chemical composition; In terms of curing methods, there are solvent curing, room temperature curing, thermal curing, and UV curing.

1. Solvent containing acrylic resin conformal coating (currently the most widely used and popular product in the market)

Features: It has the characteristics of a dry surface, fast curing time, good three-proofing, low price, transparent color, flexible texture, and easy repair.

2. Solvent-free acrylic resin conformal coating

Features: UV curing, can dry in a few seconds to tens of seconds, transparent color, hard texture, and excellent resistance to chemical corrosion and wear.

3. Polyurethane conformal coating

Features: The texture is relatively brittle and has excellent solvent resistance. In addition to superior moisture resistance, it also maintains stable performance in low-temperature environments.

4. Organic silicon conformal coating

The soft elastic coating material can effectively release pressure, withstand high temperatures of 200 degrees, and is easy to repair.

5. Fluorescent conformal coating

Features: After coating with fluorescent three-proof paint, the surface of the coating is illuminated by a purple light and shows blue, which is clear and easy to detect whether the three-proof paint is applied properly.

Reasons for using conformal coating on circuit boards

1. Protect the circuit board

Conformal coating can provide good insulation and moisture resistance, effectively protecting circuit boards from environmental factors such as humidity, pollutants, oxidation, etc., and extending the service life of circuit boards.

2. Flame retardant performance

Conformal coating usually has good flame retardant performance, which can reduce the risk of fire on circuit boards in unexpected situations and improve the safety performance of circuit boards.

3. Antioxidant performance

Circuit board conformal coating can block the contact between oxygen and the circuit board, reduce the performance degradation caused by oxidation of the circuit board, and improve the stability and reliability of the circuit board.

4. Enhance mechanical strength

The conformal coating has a certain hardness, which can enhance the mechanical strength of the circuit board and reduce the damage caused by external collision, vibration, etc.

5. Dust resistance: The surface of the circuit board is prone to accumulating dust and impurities, which can affect the normal operation of the circuit. Conformal coating can form a smooth protective film to prevent the accumulation of dust and impurities and maintain the cleanliness of the circuit board.

Conformal coating is a special formula coating used to protect circuit boards and related equipment from environmental erosion. Conformal coating has good resistance to high and low temperatures; After solidification, it forms a transparent protective film, which has superior insulation, moisture resistance, leakage resistance, shock resistance, dust prevention, corrosion resistance, aging resistance, and corona resistance.