The green standard is still a common PCB solder mask option because it allows everything to be seen clearly. White text on the green background has a high amount of contrast, and the finish isn’t bright enough to reflect too much light, so there’s a reduction in glare. Green is a common choice for boards that must be inspected, plus some may find it to be an effective method to highlighting high-quality craftsmanship because the color does not get in the way of showing off the routing.
White printed circuit board solder mask applications are becoming slightly more common because they can make a PCB look especially pretty in a clean environment. They make stunning show models in many situations. However, real-world applications can be more difficult because the white solder mask hides traces very well. Inspection can become almost impossible in some situations, especially if you’re in a room with only direct overhead light. One area where it does shine, however, is in the use of black silkscreens because of their stark contrast with white.
Black solder masks produce slightly less of a visibility concern compared to white options. Contrast is minimal but labeling and large components are easy to see. The downside is that light may catch the component and cast a small shadow, making traces that much more difficult to see. Black PCB solder mask options are also typically not recommended because of the increase in heat, which may discolor silkscreen and make the board more difficult to clean. Like white, it’s a very pretty board to observe and can create a distinct visual if you’re trying to highlight a capability of yours.
Red boards are becoming a popular option because they provide good visibility and contrast for planes, traces and even your empty space. It’s less contrast than green boards but will give a PCB a feeling of freshness when compared to stale industry standards. Silkscreens stand out well against the red.
Label-heavy boards should consider a blue liquid photo-imageable solder mask because of the significant contrast it creates with silkscreen. Traces can become much more difficult to see without proper lighting and magnification, so that’s the balance point for this blue option. Blue is often chosen for how it can look. It isn’t as striking as white or black, but it does provide a compelling aesthetic choice that implies complexity and craftsmanship, especially if you’re mounting it against an LCD. It is a little more likely to show dirt compared to some other colors.
Many new colors are emerging, but they can be difficult to manage. Yellow is a pleasing color, but it contrasts poorly with both silkscreens and traces, making it difficult to use in any real-world application. Different colors will balance different needs, such as cleanliness, visibility and style. Always try a sample before running with your new color choice.