The color of the PCB board’s surface actually reflects the color of the solder mask. One function of the solder mask is to prevent incorrect soldering of components.

Second, it helps extend the service life of components and prevents oxidation and corrosion of component leads. If you’re familiar with electronic products, you’ll notice that PCBs are typically green in color. This is mainly because the green solder mask process is the most mature and simplest, and green boards are also more environmentally friendly. Besides green, PCBs can also come in white, yellow, red, blue, matte colors, and even shades like chrysanthemum, purple, black, and bright green. The presence of white is due to its essential role in manufacturing lighting products, while the use of other colors often serves to distinguish different product samples. Throughout the entire process—from R&D to product launch—companies tailor their PCBs to specific applications: experimental boards might use purple, keyboards may feature red, and internal computer components often employ black—all distinguished by color for easy identification. As for the green solder mask, it’s the oldest, cheapest, and most widely used solder mask ink. It offers numerous advantages:

1. In PCB manufacturing, electronic product production involves both board fabrication and surface-mount technology. Several processing steps require passing through the yellow-light room, and green PCB boards exhibit the best visual appearance when viewed in the yellow-light room.

2. Secondly, during SMT assembly processing, steps such as soldering, component placement, and AOI inspection all require optical alignment calibration; the green-colored baseplate is more user-friendly when being recognized by the instrument.

3. Some inspection processes still rely on workers’ visual observation (though nowadays, flying probe testing has largely replaced manual inspection). Under bright lighting, workers continuously focus on the circuit boards; the green light is gentle on the eyes.

4. Green PCBs are relatively environmentally friendly; when waste boards are subjected to high-temperature recycling, they do not release toxic gases.

Other PCB colors, such as blue and black, contain trace amounts of cobalt and carbon, respectively. Because these materials have slight conductivity, there’s a risk of short circuits. Moreover, PCB substrates with dark colors—such as black, purple, and blue—can significantly complicate the inspection and repair processes for motherboards and are also harder to control during manufacturing. Take black PCBs as an example: in production, they’re particularly prone to noticeable color variations due to issues with process parameters or raw material ratios. Even a minor oversight can lead to significant color inconsistencies, resulting in a high defect rate. Additionally, the traces on black PCBs are not easy to distinguish, further increasing the difficulty of subsequent repairs and debugging. As a result, many PCB manufacturers rarely use black PCBs. Even in industries like military and industrial control—where product quality is extremely critical—green PCB substrates remain the preferred choice. In fact, the color of a PCB substrate has absolutely no impact on its functional performance. All of the above considerations make it clear why green is the dominant color for PCB substrates.