Printed Circuit Boards (PCBs) are the backbone of nearly all electronic devices, and while their function is universally understood, the significance of their varied colors often goes unnoticed.
The color of a PCB is determined by its solder mask—a hardened resin layer applied via screen printing—and ranges from the ubiquitous green to black, blue, yellow, red, purple, and even more creative hues like white and pink.
Far from being merely cosmetic, PCB colors carry practical implications for manufacturing, inspection, maintenance, and even environmental impact.
This article explores what different PCB colors mean, how they compare in terms of visibility and functionality, which manufacturing process determines their color, and why green has remained the industry standard despite the availability of many alternatives.
What Do PCB Colors Mean?
PCB color generally refers to the color of the solder mask that is most immediately visible when you look at a PCB board.
The color on the surface of the PCB is the color of the solder mask.
The pigment used to color PCBs is a hardened resin; the base resin is colorless and nearly transparent, and green—like other colors—is achieved by mixing color pigments.
We apply the color to the PCB using screen printing. PCB colors include green, black, blue, yellow, purple, red, and brown.
Some manufacturers have also creatively developed PCBs in a variety of colors, such as white and pink.
Are There Differences Between PCB Colors?
Green PCBs
Green is the most popular color for PCBs. As a result, many people mistakenly believe that all PCBs are green—or at least that most of them are.
Green enhances the clarity of a PCB because it provides a sharp contrast with white text, thereby improving readability.
In addition, the surface finish of green PCBs reflects less light, which helps reduce glare.
White PCBs
White PCBs look clean and crisp in a variety of environments and are becoming increasingly popular.
However, because white PCBs tend to hide trace patterns, they are still not the first choice.
That said, white PCBs provide particularly high contrast when used with black screen printing.
Yellow PCBs
I used to use yellow PCBs quite often, but they aren’t as practical anymore.
Yellow PCBs can quickly meet various needs, such as style, cleanliness, and visibility.
However, they have one obvious drawback: poor contrast with the trace patterns and screen-printed text.
Blue PCBs
Blue PCBs are considered thick boards used for labeling because they offer excellent screen-printing contrast.
While this PCB color is not as eye-catching as green, black, or white PCBs, blue PCBs are the preferred choice because they provide an excellent aesthetic option.
Blue PCBs are well-suited for use in LCDs because they do not produce sharp contrast edges or a bright background color.
Red PCBs
Due to the advantages of red PCBs, many PCB manufacturers are eager to adopt them.
Red PCBs offer excellent visibility and clearly define the contrast between traces, planes, and blank areas.
Silk screening looks particularly attractive against the red background of these PCBs.
Black PCBs
Black PCBs are just as popular as white PCBs. Both colors offer low contrast, making it easy to mark important components.
However, the main drawback of both black and white PCBs is that certain details may cast small shadows.
These shadows make tracing difficult. Therefore, black PCBs are not recommended for various high-temperature applications, as they may cause the screen-printed markings to discolor.
Furthermore, black PCBs are a mixture of cobalt and carbon, which may result in poorer electrical conductivity.
Which Process Determines the Color of a PCB?
Different colors do not affect how a PCB is manufactured.
Copper is still deposited on one or both sides, and the PCB becomes smooth as copper is added or removed.
The copper layer on a PCB is very thin, which is why the green color stands out so much.
The thin copper layer is eventually covered during the soldering process to prevent oxidation; this is achieved by the solder mask.
In many cases, the solder mask is also green by default.
With other colors, the copper does not show through clearly, making it difficult to see where the traces are.
After the traces are etched, components are placed in position.
These must be soldered in place according to the circuit board diagram.
Finally, once the components are in place, the circuit board is tested. If it passes testing, it goes into production.
Most printed circuit boards require design by an engineer, and prototypes must be created before production begins.
Are most PCBs green?
This is mainly because the green solder mask process is the most mature and straightforward, and green PCBs are also more environmentally friendly.
In addition to green, circuit boards come in white, yellow, red, blue, matte, and even chrysanthemum, purple, black, and bright green.
White is used because it is essential for manufacturing lighting fixtures.
Other PCB colors are primarily used to distinguish between different product prototypes.
Throughout the entire company lifecycle—from R&D to product launch—PCB colors vary depending on their specific applications.
Experimental PCBs might be purple, button PCBs might be red, and internal computer PCBs might be black.
Below are a few reasons to choose eco-friendly PCBs:
Glass Epoxy Material
Glass epoxy is a material used to create the solder mask layer on printed circuit boards.
In the past, this material was green, which became the standard color used by all assembly workers in the industry.
Although other colors were later introduced for glass epoxy, assembly workers still tend to prefer green.
Contrast Between Green and White Printed Text
Assembly workers often find that inspecting green circuit boards is both simple and time-saving, as they are accustomed to and very familiar with this color.
They report that inspecting circuit boards of different colors takes significantly more time.
Another reason is that, compared to other colors, green causes less eye strain during inspection.
Green is used because it also contrasts with the white text printed on the circuit board’s layout.
Widespread Use in Military Applications
Military standards have had a significant influence on the use of green for circuit boards.
Many believe that green is highly effective for circuit boards used in military applications.
The military requires suppliers to provide green circuit boards, and these suppliers also supply other customers.
These circuit boards eventually become surplus products from military suppliers.
Therefore, it is not only assembly workers, production line workers, or other customers who favor green; the military also accepts green circuit boards.
Solder Mask Exposure Rate
PCBs require a higher solder mask exposure rate; while other colors are available, they do not provide a higher solder mask exposure rate.
Darker colors, such as blue, white, or brown, have high pigment concentration, resulting in a dark solder mask.
White and black solder masks generally have the highest exposure rates.
However, green offers a dark shade that provides both a high exposure rate for workers and greater design flexibility.
Green PCBs Offer Better Machine Readability
Generally, electronic products undergo PCB fabrication and surface-mount component soldering.
There are several steps involved in manufacturing circuit boards in a yellow-light room.
When the PCB is green, it offers better visual clarity in a yellow-light room. However, this is not the primary consideration.
During surface-mount soldering, inspection must be performed by applying solder to the solder paste, surface-mount components, and the back side via AOI.
These processes all require optical alignment and calibration, and a green PCB background enhances the instruments’ recognition performance.
Green PCBs Are More Comfortable
Some inspection processes rely on workers’ visual inspection (though automated flying-probe testing has largely replaced manual inspection today).
When staring at boards under bright lights, green PCBs are easier on the eyes.
Green PCBs Can Reduce Production Costs
Because green PCBs have a wide range of applications, they can be used in both production and procurement.
Additionally, during mass production, using a single color of resist reduces production line costs, so the procurement cost of green resist is lower than that of other colors.
Consequently, green is the most common resist, offering advantages in terms of manufacturing costs and lead times.
Green PCBs are relatively environmentally friendly.
When recycled at high temperatures, used PCBs do not release toxic gases.
Other PCB colors, such as blue and black, are doped with cobalt and carbon, respectively;
Because they have weaker conductivity, there is a risk of short circuits.
Furthermore, with PCBs in dark colors—such as black, purple, and blue—the circuit board’s color is so dark that it increases the difficulty of inspecting and repairing the mainboard, and the manufacturing process is also harder to control.
Take black PCBs as an example: they are most prone to issues in the production process and raw material ratios.
Even the slightest error can cause noticeable color discrepancies, leading to a high PCB defect rate.
The traces on black PCBs are difficult to distinguish, which increases the difficulty of maintenance and debugging later on.
Many PCB manufacturers rarely use black PCBs.
Conclusion
In summary, the color of a PCB is far more than a design choice—it is a decision shaped by manufacturing practicality, functional performance, and historical precedent.
While each color offers unique advantages—from red’s excellent trace visibility to blue’s suitability for LCD applications, and white’s clean aesthetic—green continues to dominate the industry for good reason.
Its superior contrast with white text, lower glare, better machine readability in yellow-light rooms, reduced eye strain for inspectors, lower production costs, and relative environmental friendliness all contribute to its enduring status as the default.
As electronics manufacturing evolves, specialty colors will continue to serve niche applications, but green PCBs remain the gold standard, balancing performance, cost, and sustainability in a way no other color has yet matched.