Many of you probably wonder why circuit boards are usually green anyway. What is it that makes people generally come in other colors less frequently, and what is the thing about green boards? This article intends to clear up any false ideas the readers may have about the reason behind the green color of a PCB by providing just a little background information.
What Is the Green Part of a Circuit Board?
The green color on a printed circuit board is the solder mask, which protects the copper circuits printed on the fiber glass core.
Green Solder Mask
The solder mask resin itself contains green pigments. Green is the most frequently used solder resist color because of historical reasons and the convenience of its production. However, solder masks also come in other colors, such as red, blue, black, white, and even transparent.
Why are printed circuit boards green?
Most of the Printed circuit boards (PCBs) are green in the first place due to the solder mask, which is one of the outer layers, applied on top of the copper traces of the PCB to avoid oxidation of these traces and prevent shorts.The solder mask is typically green, and this has become the standard for several reasons:
A. History
The green color of PCBs was caused by processes and byproducts of early electronic manufacturing. In the mid-1900s, FR-4 laminate material and glass epoxy and resin were the norm, and this color became the default color for circuit boards; As such, it became the standard color.
B. Materials
The green color in PCBs is a result of the solder mask, which is a lacquer layer that is used to protect copper circuits from oxidation and also to prevent solder bridges from happening during the soldering process.
C. Military Standards
As many people know, green electronics were popularized by the military, especially during times of World War II and the Cold War. This was done since such devices had tactical advantages as well as camouflaging ability under bright lights. As an example, such a standard was used and aided the increasing number of military electronics and some PCB manufacturers.
D. Aesthetic and Psychological Factors
From the standpoint of aesthetics and psychology, green provides viewing ease, peacefulness, and clarity, thus turning out to be very affluent for engineers and technicians working on the circuit boards.
E. Practical Reasons
Contrast and Inspection: Green light gives out high contrast against white silkscreen printing and copper traces/lines to ease inspection and troubleshooting.
Heat Resistance and Durability: Solder masks with green coloration have been appreciated for their ability to resist heat and for maintaining their stability during soldering.
Cost Efficiency: Green solder masks can be manufactured at a lower cost due to their high commonality and optimization of the manufacturing process, which gives them a cheap production process.
Standardization: Technically standardized electronics component production ensures compatibility and uniformity of green PCBs supplied circuit boards, which is a top choice for manufacturers to maintain consistency and reliability over different products and projects.
Advantages of Green Circuit Boards
Solder mask, a green polymer layer, is the green color of green circuit boards. It is meant to serve as an anti-oxidant and bridge-prevention, covering the soldered and exposed copper traces.
Relieve Visual Fatigue
1. Optimal Contrast for Inspection: Green presents holes for inkjet printing with white silkscreen and metallic objects; as a result, green light is relaxing because it provides good contrast and is better than other colors, helping to remove visual fatigue and spot defects and issues, ensuring the survival of PCBs.
2. Comfort for Extended Viewing: Eyestrain is averted with an eye-friendly green solder mask during a long viewing period as the eyes get fatigued with visual outside/clear spots that lead to mistakes and only increase the inspection time period.
Aiding in Inspections
1. Enhancing Visual Inspections: The green PCB color allows for easier inspections of the PCB, making the assembly process much faster and more effective, which enhances the potential of detecting problems.
2. Improving Automated Optical Inspection (AOI): An AOI system utilized in PCB manufacturing uses green, to make enhancements in the visibility of components and solder joints, thus ensuring instinctive detection of deviations in the PCB images.
3. Assisting with Solder Mask Alignment: Alignment of the solder mask is therefore essential in production where traces and pads are made from copper material. The significance of the green color optimization is that it contains better alignment, fewer defects, and higher-quality PCBs.
Conclusion
Green is a typical color for PCBs because of it has historical association with classic PCBs. However, regardless of how colors define people’s color preferences, PCBs can still have different colors according to the materials they use.
In a scenario where a company needs a different color solder mask, the excess solder mask oil initially used must be removed and the silkscreen must be washed before applying a new solder mask oil.
In addition, the circuit board underneath can be assembled in different colors, such as red and blue, black and white, and so forth, even being designed to be transparent or semi-transparent is possible.
