PCB News - Why are PCB boards mostly green? Black circuit board is more high-end?

What is a PCB? PCB is the printed circuit board, which is the provider of electrical connection of electronic components. The wiring density is high, the volume is small, and the weight is light, which is conducive to the miniaturization of electronic equipment. Our common PCB boards have many colors, including green PCB boards, blue PCB boards, red PCB boards, black PCB boards, and gold plated PCB boards.

The green part is called solder resist. These ingredients are resins and pigments. The green part is green pigment. However, with the development of modern technology, many other colors have been extended. It is no different from decorative paint. The solder mask is stuck and flowing before soldering and printing on the circuit board. After printing on the circuit board, the resin will harden due to heating and finally solidify. The purpose of resistance welding is to prevent the circuit board from moisture, oxidation and dust. The only place not covered by solder mask is usually called solder pad, which is used for solder paste.

Solder resistance oil is coated on the surface of PCB board 1 to protect the circuit on the board from being short circuited by foreign matters as much as possible, 2 to cover the copper wire on the board, so that the copper wire is not easy to fall off (some exposed pads are easy to fall off, and with a solder resistance layer, it is not easy to fall off).

Of course, the most common color of PCB in the current market is green PCB. Because green PCB is less irritating to the eyes, it is not easy for production and maintenance personnel to get tired of their eyes when staring at PCB for a long time and doing business, which is less harmful to the eyes.

In addition, the whole PCB product has to go through the process of board making and SMT in the manufacturing process. During the process of board making, several processes go through the yellow light room, because the effect of green PCB in the yellow light room is better than other colors. In addition, when SMT is welding components, PCB needs to go through processes such as solder paste, patch and final AOI verification. These processes need optical positioning calibration. The background color of green PCB board has better recognition effect on the instrument.

To sum up, green circuit PCB boards are by far the most commonly used and relatively cheap in the market, so green is used by a large number of manufacturers as the main color of their products.

It is rare in the market, but also high-end is the gold circuit board. This gold is real gold, although it has only a thin layer on the board. There are two main reasons for using real gold to gild, one is to facilitate welding, the other is to prevent corrosion. Generally, such gold-plated circuit boards are mainly used for mobile phone motherboards, but not for computer motherboards, audio and small digital circuit boards.

There is also a silver PCB, also known as tin sprayed PCB. It sprays a layer of tin on the surface of the board, which is also convenient for welding. However, its corrosion resistance is not strong. If it is exposed to the air for a long time, its pad will be easily oxidized and rusted. General small digital circuit boards are basically tin coated PCB boards, because they are cheap and low cost.

Why are PCB boards mostly green? Black circuit board is more high-end?

Of course, each factory will use two colors to distinguish high-end series and low-end series in order to distinguish its own product grade. For example, Asus, the company that makes computer motherboards, has a low-end yellow board and a high-end blackboard. Yingtai's blue board is high-end, while the green board is low-end.

At present, the cost of black PCB is higher than that of PCB with other colors, but this does not mean that black PCB has better electrical performance. In production, black PCB is the most difficult for holes, so the yield rate is relatively lower than that of PCB with other colors.

With the rapid development of electronic technology, the process requirements of PCB circuit boards in each industry are different, for example, there are gold and copper in the circuit boards of mobile phones and computers. From the color, it can be seen whether the manufacturer has cut corners. In addition, the circuit inside the circuit board is mainly pure copper. If exposed to air, it is easy to be oxidized, and the outer layer must have the above protective layer.