Have you ever wondered why PCBs are green? This text will explore this phenomenon by introducing what the green part is, why are circuit boards green and how important it is.
What Is the Green Part of A Circuit Board
In fact, circuit board is originally brown, but what we see is the green solder mask covering on its surface.
Pcb Green Color Code
|
PCB Color |
Color Code | Contrast |
| Green | #008C4A |
Good |
Advantages and Disadvantages of Green Color for Circuit Boards
Green is less irritating for human eyes. It reduces the eyestrain of production and maintenance workers when staring at PCB boards for a long time.
It is at a lower cost. Since green is the mainstream color in the PCB production process, the purchase amount of natural green paint will be larger. Thus, the purchase cost of green paint will be lower than that of other colors. Moreover, the use of the same color paint in mass production can also reduce the cost of line change.
Green board as background improves the inspection preciseness of manufacturing machine. Each board in the SMT welding has to go through pick-and-pack and the final AOI verification. Both these processes contain optical positioning calibration, which needs a green background color for easy instrument identification.
Why Are Printed Circuit Boards Green?
First, let’s take cost and time into considerations. In the PCB manufacturing process, green ink can dry quickly, speeding up the manufacturing cycle. Therefore, green ink has been widely used in PCB manufacturing. More and more, due to the wide use of green ink, manufacturers can obtain better procurement prices, thereby reducing costs.
It provides easy identification for human’s eye and manufacturer calibration. Green background allows engineers and technicians to easily identify the type and function of the PCB board for better maintenance and repair.
Easy development. In the PCB manufacturing process, chemicals are used to remove those unnecessary parts. in chemical development process, green is more easily soaked by the developer, making the unwanted part easy to remove.
Last, Historical reason is also an important factor. In the early stages of PCB manufacturing, green ink is the only available paint color due to manufacturing technology limitations. With the development of technology, other colors of ink have gradually been introduced into the PCB manufacturing process, but green ink is still one of the most popular colors.
Do Printed Circuit Boards Have to Be Green?
The solder mask is not necessarily green. The color of board depends on what the PCB designer wants to make it. In addition to green, there are red, yellow, blue, purple, black board, but green board is still the most common one.
Other Available Circuit Board Colors
| Other Color | Description | Application |
| Blue PCB | Adopt blue photosensitive dye to form a solder resistance layer, which has a good appearance and recognition. | Apply in the brand product whose style is in blue. |
| Black PCB | Good heat dissipation performance | High-power device, such as high-performance computers, audio equipment |
| Red PCB | Red photosensitive dye with high resistance has good thermal stability. | Devices used in high temperature and bad environment, such as high-end communication equipment and military electronics. |
| White PCB | PCB looks particularly contrasting in black screen printing | LED |
Why Are Some Circuit Boards Blue?
In addition to green, blue is also a color frequently used on PCB board. It usually aims at fit the board into the same style as the color of product brands. Blue PCB board uses blue photosensitive dye to form a solder resistance layer, which has a good appearance and recognition. It is also adopted to thick board with labels, because it provides significant screen printing contrast. Generally, people apply blue PCB on the LCD, since it does not produce sharp contrast edge and bright background color.
What Is the Difference Between Blue and Green Circuit Board?
Compared to blue board, the material of the green board is stiffer and more suitable for complex circuit. Also, the suitable materials of blue and green board are different, leading to different electronic performance and application. For example, blue board is usually made of glass fiber plate, coating with a layer of copper on its surface. In contrast, green board is commonly made of FR-4 glass fiber plate or CIM-3 fiber plate, coating with a layer of green photosensitive film on its surface.
What’s more, the surface treatment towards blue board and green board are various. For instance, blue board should be treated with gold, while green board need no treatment before welding and printing. The reason of difference is that green board has been coated with a photosensitive film, which can protect the copper layer on the surface of the board from corrosion. Therefore, it is necessary for blue PCB to receive gold settling treatment to prevent oxidation or corrosion.
Furthermore, due to their difference board material and surface treatment, their application is, accordingly, different. In on hand, blue board is suitable for high-precision, high-reliability circuit, such as aerospace and medical equipment. In the other hand, the green board is suitable for ordinary electronic products, such as personal computers, mobile phones, MP3s and so on.
Does the Color of A Circuit Board Matter?
To be honest, color has slight impact on the performance of the motherboard. And it does not play a very important decisive role in PCB design. We believe that different colors of PCB motherboards mainly serves the good look of the product. And take it easy to consider which color you should use on the board when designing PCB.
But what should not be ignored is that strict control of every detail in each round of production is the premise of a high-quality PCB board. And board color can be a concession towards the factors like good quality and good electrical performance.
