How Green Became the Standard Color for Circuit Boards

Simple Things - Surprising Historieslooked at the history of circuit boards to find out why almost all of them are a particular shade of green (like the Laughing Squid logo). It turns out that circuit boards start out dull but turn green when a liquid solder mask is applied and hardens to protect the pathways.

We explain why almost all circuit boards are green, exploring the process step by step using real science and verified historical methods.

They also explain how the military chose this particular shade of green as the industry standard.

Early protective resins naturally had a muddy greenish brown tint to them, but the military rigorously tested differentpigments and combinations. They found that a specific shade of green performed exceptionally well in adverse environments. Because the military bought these boards by the millions, factories standardized their assembly lines for green resin.

There was also a human element that led to the decision of this particular shade of green.

Scientists realized the human eye is highly sensitive to green light, making it the most relaxing color for our brains to process. ...Green also provided perfect visual contrast. The shiny silver solder popped and the tiny white instructional text printed on the boards was incredibly easy to read. Switching to green massively reduced manufacturing errors.

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