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Why are most PCBs mostly green?

PCB green oil, also known as solder mask oil, is a special oil applied on the surface of PCB. So why do most circuit boards use green oil?

The Key Functions of PCB green oil：

1.Protecting Circuits and Extending Lifespan
PCBs are covered with intricate copper traces and solder points, which are highly susceptible to oxidation and corrosion when exposed to air. The solder mask acts as a protective shield, isolating the circuits from external environment, thereby greatly extending the service life of the PCB. Especially in a humid environment, this protection is especially critical to prevent copper traces from rusting and ensure circuit stability.

2. Insulation to Prevent Short Circuits
With minimal spacing between traces, without the insulation protection of green oil, are prone to short circuits caused by accidental contact between conductive paths. The solder mask provides an insulating layer that ensures electrical safety and supports reliable device operation.

3. Reflecting Quality and Enhancing Appearance
The color and uniformity of the solder mask can also indicate the quality of the PCB production process. A vibrant and even green finish often signifies high manufacturing standards, whereas uneven colors or defects may hint at process issues. In high-end electronic products, solder mask quality is held to even stricter standards, as it impacts both performance and aesthetic appeal.

Conclusion

Though it might seem like a simple layer of paint, the solder mask on a PCB is vital for protection, insulation, and aesthetics. The choice of green combines technical, economic, and functional advantages, making it the industry standard.