Have you ever wondered why the PCB boards are green? Because of the solder mask layer. This is the top layer, above the copper foil that is giving the printed boards their green color. The main purpose of this layer is to insulate the copper traces from accidentally contacting any of the solders or metal. The common color is green, but keep in mind that the solder mask could be manufactured in nearly all possible colors.
Green is the signature color of the circuit board, and there is a huge science and logic behind this color. Many experts have given their logical explanation about why giving PCBs the green color. These reasons are discussed below.
Background History of Deciding the Green Color:
There is a little background history as well that why green color is the standard color of the Circuit boards. This is because the green color seemed considerable and acceptable for the eyes of the assemblers. It looked effective to the assemblers when they saw the tracks of the circuit board. Before the green color, the original color was in shades of brownish-yellow and the hardener was a darker shade of brown. When the shade was mixed it gave a shade of honey brown that did not seem acceptable to the assemblers. Then they tried to add a little bit of red color but it made the shade look more dark brown. Then they tried adding more yellow which turned into this shade of dark green. It seems acceptable to everyone and successfully became the standard color.
Reasons why Circuit Boards are Green in Color:
There are multiple reasons told by different experts why the circuit boards are usually green in color. These different reasons are discussed below:
The Glass Epoxy Material:
Glass Epoxy is a material that was used in manufacturing the solder mask of the circuit boards. This material used to come in a green color that became the standard color for all the assemblers in the industries to use the same Glass Epoxy. By that time, there were also some colors introduced for Glass Epoxy but the assemblers always considered using the green color one. This trend of green color, due to it being so common, became cost-effective too. That is why some experts say that the Glass Epoxy is one of the reasons why the circuit boards are always green in color.
The Contrast of the Green Color with the White printed text:
Assemblers often find it easy and less time-consuming to scan the green circuit boards because they are already habitual and pretty familiar with this color. They say that takes a lot of time to scan circuit boards of some different color. Another reason is that the green color creates less strain on the eyes while scanning as compared to other colors. The green color is used because it also contrasts the text printed in white on the routing of the circuit board. That is why the line workers prefer using green color while scanning the circuit board
The Color Green used for Military Purposes:
Some research was based on how military standards were a great influence on the green color of the circuit boards. This all started in the USA and the military of the USA considered this green color to be highly effective in the circuit boards that were also used for military purposes. The military demanded the green circuit boards from the suppliers who also supplied them to other customers. Green military PCB assembly boards became surplus for the suppliers from the military. So not only do the assemblers, line workers, or other clients consider the green color, but the military forces also accept the green color of the circuit boards.
The Rate of Exposure with the Solder Mask:
A higher solder rate is required for the circuit boards. There are other colors too but they do not provide a higher solder mask for the circuit board. Those colors that have dark shades like blue, white, or brown have high pigmentation and therefore they have dark-colored solder masks. Mostly the white and black solder masks are high in exposure rate. However, the green color provides a dark shade for the exposure rate to the workers and high tolerance in the design.
Some Other Colors of the Circuit Boards:
Circuit boards come in different colors and have different colors of solder masks as well. The colors mostly differentiate between multiple popular brands and companies that produce and manufacture them. The colors are decided during the production process, once it is observed that the colors meet all the criteria, and are acceptable by the assemblers. Many manufacturers and assemblers also use other dark colors as an alternative to green-colored solder masks. Some alternative colors that are considered are as follows:
The white-colored solder masks are also created by some companies due to their shade and appearance. They are used especially for models to be shown. Now the question arises of how can the print of the white text be visible. Well, for this to be visible the black color is used for the silkscreen as it stands out boldly and perfectly.
The black printed circuit boards are also used as they make it easy to see the labeling. The black color also absorbs heat big time.
Some assemblers also go for the red colored circuit boards because of the appealing color. The color gives a fresh vibe and due to this, they consider red color as an alternative to green color.
The high rate of exposure to contrast is found in the blue-colored circuit boards. These circuit boards handle the applications well and that is why they are considered as an alternative label.
The above-mentioned reasons were given by different experts and even the PCB assemblers who manufacture the circuit boards. There is therefore not one main reason as to why the circuit boards are usually green in color. These reasons, however, are logical and scientific reasons why most customers and manufacturers consider green color.
Where You Can Buy Printed Circuit Boards with Custom Solder Mask Colors
PCBONLINE is a one-stop PCB manufacturer, which is especially good in advanced circuits. You can buy printed circuit boards in any color from this PCB company. You can take a look at its capability below:
- Layer: 1 ~ 42
- Laminate: Normal Tg/Hight/Lead-free/Halogen Free
- Surface finishing: OSP/HASL/LF HASL/Immersion ENIG/Immersion Tin/Immersion Silver
- Board thickness: 0.15 ~ 3.2 mm
- Max board size: 500 x 580 mm
- Copper thickness: Inner Finish Copper: 1-4OZ
- Outer finish copper: 1-7OZ
- Min. Line width/spacing: 0.0635 mm/0.0635 MM
- Min. CNC drilling size: 0.15 MM
- Min. Laser drilling size: 0.075 MM
- HDI stack up 1+N+1，2+N+2，3+N+3
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