Printed circuit boards are the most common component found in all electrical gadgets. Epoxy resins and reinforced glass fiber are used to create these little boards. A layer known as the solder mask is positioned on the outside of the printed circuit board (PCB). The distinctive green hue of circuit boards is due to the solder mask. Despite the fact that current PCBs may be red, white, blue, and many other colors, the great majority are still the typical green color. There are a few things to know about the green color seen on PCBs, and this article will help you in clarifying any doubts.
What Is Green PCB?
Although it is called a “green” printed circuit board, it is not completely green all the way through. The outer layer of resin, known as the solder mask or solder resist/oil, is the only component that is green. This is a solid resin containing color pigments that are silkscreened onto the boards. Solder mask serves to shield the electrical traces beneath from moisture and dust and to regulate the flow of molten solder. The actual core of a standard FR-4 circuit board is a simple, dull yellow hue, but the solder mask can be blue, red, yellow, black, or white, among other colors. There are even more exotic hues available for the extravagant, like orange, pink, and purple, as well as matte variants and mixed-color boards.
Why Most of the PCBs Are Green?
Green is the most common color for PCBs for a number of different reasons. The majority of motherboards and other important PCBs are green, while there are various colors available.
The simplest probable explanation for why circuit boards are green is as follows: Glass epoxy, which was formerly used to manufacture solder masks, is by nature green. Even with the availability of solder mask coatings in a variety of colors, many manufacturers continued to use green solder masks. As a result of their prevalence, green-colored solder mask materials are now often more affordable. As an aside, the fiberglass boards themselves are a greyish-brown tint. As a result of the safety provided by solder mask coating, however, it is rarely seen on current PCBs.
2. The Military’s Role in PCB Development
Some people conclude that the military was the reason why the color green was chosen and why it became the standard. The United States military researched the effectiveness of PCB colors and found that green performed the best, especially in low-light conditions.
The military determined, as a result of their experiments, that green-printed circuit boards would be the standard. The PCB makers who sold their circuit boards to the armed forces also served a wide range of civilian customers. The majority of PCBs are not viewed by anybody other than the producers; therefore, there was no need for businesses to produce them in other hues.
3. Green Is Relieving
Working on such small circuits might be tiring, but studies show that exposure to green light can have a calming effect on the body and reduce feelings of exhaustion. Moreover, the receptors or cones in human eyes are highly sensitive to green impulses. Thus, there is a greater difference between circuit tracks, electrodes, silkscreen etching, and vacant spaces. Simply by seeing the panels from the exterior, faults in the outer layers may be immediately observed.
4. Green PCBs are Environmental Healthy
Green solder mask oils are mostly composed of chlorine. Chloride and Bromine, which are included in green PCB materials, are halogens that pose substantial health and environmental risks if illegally disposed of. It is possible to solder using free halogen oils and boards. A halogen-free solder mask may be simply replaced with a different color.
The exposure rate of the green solder mask might potentially be a factor in the circuit board’s green color. Since darker color solder masks (blue, black, and white) contain more pigmentation, they require a greater exposure rate. The greatest exposure rate is needed for black and white solder masks. Additionally, selecting a green solder mask will enable the customer to attain tighter design tolerances.
In many cases, the rigid board’s component side will include a white silk-screened ident. To make this layer’s text accessible by humans, green provides the best contrast. According to Peter Skippings, one of the co-founders of Artetch Circuits in the late 1960s, this notion was the closest to the truth. Peter’s team produced standard PCBs by screen printing, etching, printing with green solder resist, and finally, roller tinning the exposed copper pads on the board. The solder resists shielded the copper tracks on the PCB from the heat generated during roller tinning. Peter stated that green was the only color available, and since it had the necessary heat resistance, it was utilized exclusively.
As a result, it appears that there is no one explanation for why PCBs are green; yet, as with other items, green is frequently the most cost-effective color for mass manufacture.
Is It Necessary To Have Green-Printed Circuit Boards?
The majority of PCBs are green; however, this is not a requirement. Choosing a different color for a PCB will not affect its functionality or the device it will power. However, the resolution to it is variable. This implies the solder mask is less visible on boards with varied colors. In addition to green, the most popular hues include red, blue, black, and white. However, all the hues of the rainbow are present on certain circuit boards.
Typically, various hues correspond to certain device components. In computers, motherboards are typically color-coded green. This allows computer technicians to rapidly locate the most vital PCB on their machines. Other boards for lesser activities are frequently colored differently to indicate their function.
Different colored circuit boards are more difficult to deal with than green ones. For instance, black circuit boards have difficulty with the heat necessary to press them together; they frequently become overheated. Whiteboards are challenging to read. Red is a versatile color since so many hues shine out against it. In addition, blue is eye-friendly and effective.
PCBs are typically produced from green materials for numerous reasons. There are a number of significant reasons why green is the standard for printed circuit boards. The color is easy on the eyes while providing adequate contrast for inspectors to clearly see the board’s components and traces.
PCBs are not required to be green; however, altering the color might somewhat slow down production because other colors are not as pleasing to the eye as green. In reality, aside from an LED lights board, the color choice of solder mask paint of other colors is determined by the developer’s or manufacturer’s preference, and white solder mask ink has a higher reflecting efficiency. It has no direct impact on the role of the board. Therefore, the green PCB is superior to other PCB colors.