Why Are Circuit Board Green?

The most important component that man has developed is the circuit board. Every electrical device that exists till date, includes a circuit board in its hardware. We should be thankful to Mr. Paul Eisler because he developed the first circuit board in 1936. Without this useful component, we would not have been able to use any electrical device. People have many doubts why are circuit board in green color since the invention of the circuit board. The explanation to this question is given below in the article.

Why are circuit boards green?

There are various reasons why are PCBs green. These reasons are mentioned below in this article.

  • One of the main reasons why are PCBS green is because of the solder mask. The solder mask is used on the circuit board to secure the copper components on a circuit from short circuits and other errors. The green colour appears on the PCBs because of the color of the solder machine.
  • Another reason why are circuit boards green in colour is because of the efforts of the Army. Army played a major role in the development of PCB during the 19th century. The developers paid tribute to the Army by printing these boards in green colour.
  • Circuit boards tend to be green in colour because this helps in the investigations of errors in a circuit board. In the initial’s days of industrialization, there were many restrictions on technology. Due to this reason workers had to check each circuit board manually. It was a difficult task. The reason is that the eyes of these people used to get tired, by checking immense number of circuits. So, neurologists and psychologist decided to use green color for the circuit boards. The reason for choosing a green colour is it has a moderate wavelength. This colour provides relaxing effects to the eyes of humans. These experts have discovered that sensors within a human eye are most sensitive to green light. The contrast of green colour provides aid to the people, who inspect problems in circuit boards. Today PCB developers take advantage of flying probe techniques and automatic optical inspection (AOI) for solving all errors in a circuit board.
  • The reason why are PCBS green is because it reduces the production costs. There is the usage of Solder masks in silkscreen methods. Oil moves across a screen mesh and, the circuit board is placed under it. After this, the board is removed for curing and, the next circuit takes the position in the mesh. But if you want a new colour for the circuit board, you would need to waste the oil and use a new silkscreen. The reason is one silkscreen station contains one colour. By changing the colour of a board, a new silkscreen is to be purchased. Another reason why are PCBs green is because green has the least shades. The manufacturer would not need to place a new silkscreen every time and would save lots of money.
  • The green colour is used in the manufacturing of circuit boards because of its reliability. The green colour produces solders mask dams of 0.1mm. Other colours like red, yellow and blue produce mask dams of 0.12mm. Black and white colours produce the least dams, which are of 0.15mm.
  • Initially, circuit boards were of a brownish yellow colour. It was the base model. A harder model was made that was of a deep muddy brown colour. The mixture of both of these models produced a circuit board, which had a honey brown colour. It did not seem to be very appealing to humans. Manufacturers made amendments to the circuit boards by adding red and blue pigments to them. This turned the colour of the circuit boards into dark brown. Still, this did not seem to be attractive. Now what manufacturers did was that they added yellow and some blue colour to the circuit boards. The outcome was circuit boards with green colour. The green colour was accepted by the majority of the people. Due to this reason, green colour is made the standard for circuit boards
  • A reason why are circuit boards green in colour is because of its price. The production cost of green colour is the least among all the colours. Due to this reason, many people prefer this colour for the circuit boards.
  • The reason why are circuit boards green in color is because of the exposure it gets. During the fabrication process, a PCB needs to go through an exposure room, which is lightened with Yellow light. The green colour is used for Circuit boards because it gives the best visuals as compared with the rest of the colours. During the SMT soldering process, a tin coating is done on the PCB. This process requires optical alignment and, green is the colour that gives the best clarity and resolution.
  • Many manufacturers don’t use other colours than green, as it is set as the standard. They do not want to try out new colours and designs. The feel that this move could drive their companies into an immense loss. These companies also believe that by using new colours they would waste their time and money. They want things to operate in a way, as they have been operating for previous years.

Can You Use Any Other Colors Than Green for The Circuit Boards?

Yes, you can use any colour that you want.

Initially, the core of a circuit board is in dull yellow. The solder mask, which helps in the manufacturing of the circuit boards, is available in a wide range of colours. Exotic colours like orange, pink and others are also are used for circuit boards.

White colour circuit boards are used by companies only for giving the models a good appearance. The text on these models is black in colour, because white text is difficult to read.

Red colour is used for circuit boards because it has similar contrast like the green colour. The red colour provides the circuit board a clean and modern look.

Majority of people use green colour in the manufacturing of circuit boards. The reason is that they do not want to take the risk by choosing new designs and colours. Also green colour helps the experts in finding errors in the circuit boards.

How Are PCBs Developed?

The process of PCB manufacturing a circuit board is intense and consists of several steps.

1. Design:

First of all, you would need to create a blueprint for your circuit board. By using several computer soft wares, you can develop your design.

2. Print the design:

Not all printers can print the design of a PCB. A printer called plotter is used for this process. The print of this printer will show a detailed version of your circuit board. It would consist of 2 inks inside its layers.

The first ink is used for displaying the non-conductive area. The second ink will display the copper parts of the circuit.

3. Development of a Substrate:

The substrate is an item that is insulated. Due to this, it provides grip to the elements of the circuit. Copper wiring is attached to both sides of the circuit.

4. The inner layers:

The printing of the inner layers is done to laminate the circuit board. The inner layers are printed on a photosensitive film. It would get hard when UV falls on the circuit board. The inners layers provide aid in stabilizing the design and print of the PCB. PCB Manufacturing make holes in the circuit as it provides alignment to it.

5. Passing through UV light:

When the circuit is aligned, it is exposed to UV light. It makes the inner layer of the circuit board hard. This light even shows the paths of copper in the circuit. Now the circuit board is cleaned by an alkaline chemical. It helps to reduce the waste on the circuit board.

6. Removal of waste copper:

To remove excess copper from a circuit board, a specific chemical is used. This solution does not damage the circuit in any way.

7. Investigation of errors in a circuit:

Once the layers are developed, experts analyze the alignment of the circuit board. These experts use an optical punch tool. This device makes a pin in the holes that enhances the alignment of the circuit board. After this is done, another tool is used, which detects any other errors in the circuit board. After these investigations are done, the circuit is declared error-free.

8. The lamination procedure:

As all the layers of the circuit board are aligned, a shape of it develops. In the start of the lamination procedure, metals clamps grab the circuit board. First, an epoxy resin layer is applied on the circuit board, as it moves through the basin. After this, substrate layers is applied the board, then a copper layer and another epoxy layer. In the end, the last copper layer is applied to the board.

9. The pressing procedure:

The components of the circuit board are pressed using a mechanical press. If this process is done in the right way, the circuit board is forwarded to the lamination sector. Here, heat and pressure are provided to the circuit board. The epoxy layer melts, due to which all the other layers combine.

10. The Platting point:

After all the previous processes are successful, the plating process starts for the circuit board. A special solution is used for plating each layer of the circuit. After this, specific solutions are used for removing debris from the circuit board.

11. Development of outer layer:

Just like the inner layer, the outer layer is designed before manufacturing it. UV light is used for making the outer layer hard. This light removed the excess photoresist from this layer. After these processes, this outer layer is plated in the same way as the inner layer. A chemical is used to remove the debris from the outer layer, once it is plated. A tin guard is added to the circuit board. This guards the copper and develops links on the Circuit board.

12. Solder procedure:

Epoxy is used on the solder film. This film develops a green colour on the circuit board. The excess film of solder is removed with a UV light.

13. Usage of Silk-screening:

This an important PCB manufacturing step. Special information is noted down on the circuit board with a silkscreen. When this is done, a layer of coating is done on the circuit board. After this process is done, the board is sent towards the curing sector.

14. Finishing touches:

The finishing on a circuit board is done with a solder. The better the finishing, the longer the circuit board will last.

15. Trails of the circuit board:

Once thePCB manufacturing and assembly process of a circuit board is done, it is sent to an expert. These expert tests the circuit board in every way. If the circuit board passes all tests, it is labelled error-free.

These are all the steps for the manufacturing and development of a circuit board.

Can You Customize The Printing and Development of A Circuit Board?

Custom PCB printing can be done. Many Manufacturers do custom PCB printing. They note down all the needs that are required by their customers. Customers can provide designs of their choices and choose the colour of the circuit board that they want.

These customers send these details to the manufacturers for the development of a custom circuit board. Manufacture delivers a custom circuit board to its customers within a span of a few days.

If the needs of the customers are not fulfilled, they can ask the manufacturers to makes amendments to the circuit boards.


All in all, circuit boards are an important device. These are used in the running of the majority of the electrical devices in the world. You have now found answer to your question about “Why are circuit boards green”. But you are not bound on choosing the green colour. You can choose any colour for the circuit board that you prefer.

Leave a Reply

Your email address will not be published. Required fields are marked *