Green is the most common visual characteristic of Printed Circuit Boards (PCBs). Its selection is not arbitrary; rather, it results from a complex interaction of scientific, technical, and economic considerations. These boards form the fundamental structure of electronic systems, containing copper traces that connect various components within electronic circuits. The surface of PCBs is covered with a layer known as the Solder Mask, an insulating layer that protects copper traces from oxidation and damage, while preventing unwanted electrical short circuits. The green color used in this layer provides strong visual contrast between different elements, such as copper paths and printed labels, facilitating visual inspection and reducing errors during manufacturing and maintenance processes. From a visual perspective, green is comfortable for the human eye, as it falls within a spectrum to which the eye is highly sensitive, thereby reducing visual fatigue during prolonged inspection tasks. Physically, the materials used in green solder masks exhibit excellent electrical insulation properties, along with resistance to heat and humidity, which enhances the stability of the board’s electronic performance under varying operating conditions. Historically, green has been associated with the early development of PCBs, where it demonstrated high efficiency and reliability, leading to its widespread adoption as an industry standard. Its relatively low cost compared to other colors has also made it the preferred choice in mass production. Although alternative colors such as black and blue have emerged for aesthetic or marketing purposes, green continues to maintain its dominance due to its balance between technical performance, visual clarity, and economic efficiency. In conclusion, the green color in PCBs represents an integrated model that combines functionality and aesthetics, clearly reflecting the deep relationship between design and science in the field of electronics. Almustaqbal University, The First University in Iraq.