A characteristic that often goes unnoticed in printed circuit boards is their color. Achieving a good design is critical for detecting errors and improving their repairability when a component fails, but some manufacturers tend to favor green. Why? Is there a specific advantage over other colors, or did it simply become established over time? Today we try to find out…
Just a simple Google Images search for 'PCB' is enough to see that the dominant color is green. In fact, that color is the first thing that comes to mind when we think of printed circuit boards, but we don't give it much more attention. After all, color isn't relevant; all we care about is good functioning, followed by flexibility in repairing it. So... where does green come from? Who made it a massive option, so to speak?
The Green Color of Printed Circuit Boards
In recent generations of products, manufacturers decided to adopt alternative colors (black became very popular among motherboards and graphics cards, for example), so there is no technical restriction in current production lines, but first we must answer a more essential question: What is 'green'?
Green PCBs no longer appear much in the computer market, but there are still examples like this Supermicro motherboard.
Green is nothing more than the solder mask, a lacquer whose main purpose is to protect the circuit from corrosion, rust, foreign substances, and accidental bridging. Going back to the roots of electronics, we find that the first circuits were not green. In fact, there wasn't even a substrate, and connections 'floated' in a vacuum.
As for the origin of green itself, all we have are hypotheses. The first suggests that the original resins used in mass production of circuits gave a green color at the end of processing. Another suggests that green was added in response to the tendency of those resins toward brown, which was hard to differentiate from rust. Then we have green with a military source, as it would have been a requirement of the US Army.
Then there's a combination of minimizing eye fatigue, greater contrast with white text, lower costs, and a reduction of errors thanks to the precision of green in the most compact areas of a circuit.
Finally, the folks at Ustek describe colors as part of a standard: green circuits use tin with lead, blue circuits follow the RoHS directive, and red is for prototypes. Different interpretations, but at the end of the day, green in circuits has a touch of mystery.
