PCB Tech - Why are circuit boards green

I don't know if you have found such a situation, most of the PCB circuit boards are green, while other color circuit boards are relatively rare. Why is this? Others say that the black circuit PCB represents high-end, is that really the case?

First, let's get to know this green circuit board.

Printed circuit board usually consists of pads, vias, solder mask, silk screen, copper wires, various components and other parts. Among them, the solder mask (solder mask) refers to the part of the printed circuit board to be painted with green oil. 

In fact, solder mask ink is not only green, but also red, yellow, blue, purple, black, etc., but green is the most common.

The role of solder mask:

1. Prevent physical disconnection of conductor circuits;

2. In the welding process, prevent short circuit caused by bridging;

3. Only solder the parts that must be soldered to avoid waste of solder;

4. Reduce copper pollution to the soldering trough;

5.  Prevent insulation deterioration and corrosion caused by external environmental factors such as dust and moisture;

6. With high insulation, it is possible to increase the density of the circuit.

Then why are most of the PCB boards green? The main reasons are as follows

1. Green is less irritating to the eyes. Since childhood, the teacher told us that green is good for the eyes, protects the eyes, and resists fatigue. The production and maintenance personnel are not prone to eye fatigue when staring at the PCB board for a long time, and it is less harmful to the eyes.

2. Lower cost. Since green is the mainstream in the production process, the purchase of natural green paint will be larger, and the purchase cost of green paint will be lower than other colors. At the same time, using the same color paint in mass production can also reduce the replacement cost.

3. When the board is soldered in SMT, it needs to go through tinning, post filming and final AOI verification. These processes all need to be optically positioned and calibrated. The green background color is better for the recognition of the instrument.

Black PCB board is more high-end?

From about 2007, everyone began to pay attention to the color of the PCB circuit board. This is mainly because the high-end versions of the first-tier manufacturers such as ASUS and MSI have adopted the black PCB color design, so people gradually think that the black PCB board must be It is high-end. But in fact, this perception is not correct.

The difference between black PCB and other color PCBs such as green PCB, blue PCB and yellow PCB lies in the color of the solder mask applied at the end. If the PCB design and manufacturing process are exactly the same, the color will not have any effect on performance, nor will it have any effect on heat dissipation.

Regarding the black PCB, since the traces on the surface are almost completely covered, it causes great difficulty in the later maintenance. Therefore, it is a color that is not convenient to manufacture and use, and the black PCB is the most difficult for holes, so the yield rate Relatively speaking, it is lower than other color PCB boards, so the price of black is relatively more expensive.

The reason why "color represents high-end or low-end" is because manufacturers prefer to use black PCBs to make high-end products, and use red, blue, green, and yellow to make low-end products. The summary is: the product gives the color meaning, not the color gives the product meaning.

Whether it is a black PCB board or a green PCB board, a good PCB circuit board is a good PCB board with good performance and good heat dissipation.