Why are most of the circuit board PCB green?
2024-02-22
The color of the surface of the PCB board is actually the color of the solder mask. The solder mask can prevent the occurrence of component misalignment, and the second is to delay the service life of the device and prevent oxidation and corrosion of the device line. If you know more about electronics, you will find that the PCB color is generally green. This is mainly because the green solder mask process is the most mature and simple, and the green board is also more environmentally friendly.
In addition to green, PCB boards are also available in white, yellow, red, blue, matte colors, and even chrysanthemum, purple, black, bright green, etc. The existence of white is because it is a pigment that must be used in the production of lamps and lanterns, and the use of other colors is mostly to distinguish different product samples. In the whole stage from R&D to product landing, according to the different uses of the PCB board, the experimental board may be purple, the key board will be red, and the board inside the computer will be black, which will be distinguished and marked by color.
As for green oil, its solder mask ink is the oldest, cheapest and most popular. There are many advantages:
1. In PCB processing, the production of electronic products includes board making and patching, during which several processes have to go through the yellow light room, and the green PCB board has the best visual effect in the yellow light room;
2. Secondly, in the SMT chip processing, the steps of tinning, placement and AOI calibration all require optical positioning calibration, and the green bottom plate instrument is more friendly when identifying;
3. Some of the testing processes rely on workers' observation (but now most of them use flying probe tests instead of manual ones), keep staring at the board under strong light, and the green color is friendly to the eyes;
4. Green PCB is also more environmentally friendly, and no toxic gas will be released when the waste board is recycled at high temperature.
Other PCB colors, like blue and black, are doped with cobalt and carbon, respectively, and there is a risk of short circuit due to their weak conductivity. In addition, like black, purple, and blue lights, the color of the PCB substrate is too dark, which will increase the difficulty of inspection and maintenance of the motherboard, and the process is not easy to control. Taking the black plate as an example, the black plate is most likely to be due to the process and raw material ratio problems in production, and a slight carelessness will cause obvious color difference, resulting in a high PCB defect rate. The traces of the black circuit board are also not easy to identify, which can make it more difficult for later repairs and debugging, and many PCB factories do not use black PCBs very much. Even in the field of military industry and industrial control, products with extremely high quality requirements mainly use green PCB substrates. The color of the PCB board does not affect its performance in the slightest.
To sum up, it is not difficult to understand why the color of the PCB substrate of the circuit board is mainly green.
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