Is the better the PCB board’s appearance, the better it is to use? What effect does the color of solder mask ink have on the board?

“The color of the surface of the PCB is actually the color of the solder resist. The solder resist can prevent the occurrence of wrong soldering of the components, and delay the service life of the device, and prevent the oxidation and corrosion of the device Circuit.

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Many people use the color of the PCB to distinguish the quality of the board. In fact, the color of the motherboard has nothing to do with the performance of the PCB.

PCB board is not that the higher the value, the easier it is to use.

The color of the surface of the PCB is actually the color of the solder resist. The solder resist can prevent the occurrence of wrong soldering of the components, and delay the service life of the device, and prevent the oxidation and corrosion of the device circuit.

If you understand the PCB boards of large companies such as Huawei and ZTE, you will find that the color is generally green. This is because the green technology is the most mature and simple.

In addition to green, the color of PCB can be described as “bells and whistles”: white, yellow, red, blue, matte colors, and even chrysanthemum, purple, black, bright green, etc. The existence of white, because it is necessary to make lighting products The colors used, and other colors are mostly used for labeling products. During the entire stage of the company from R&D to product landing, depending on the different uses of the PCB, the experiment board may be purple, the key board will be red, and the internal boards of the computer will be black, and they are marked by color.

The most common PCB board is the green green board, also called green oil. Its solder mask ink is the oldest, cheapest and most popular. In addition to mature technology, green oil has many advantages:

In PCB processing, the production of Electronic products includes board making and patching. During the process, there are several processes to go through the yellow light room, and the visual effect of the green PCB board in the yellow light room is the best; secondly, when the SMT is processed, the tin is applied The steps of, patching and AOI calibration all require optical positioning calibration, and the green bottom plate is more friendly when it is recognized by the instrument.

Part of the inspection process relies on workers to observe (but now most of them use flying probe testing instead of labor), staring at the board under strong light, green is friendly to the eyes. Green PCBs are also more environmentally friendly, and will not release toxic gases when they are recycled at high temperatures.

Other PCB colors, such as blue and black, are doped with cobalt and carbon, respectively, because of their weak electrical conductivity, and there is a risk of short circuit.

Taking the black board as an example, the black board is most likely to cause color difference due to process and raw material problems in the production, resulting in a high PCB defect rate. It is not easy to distinguish the traces of the black circuit board, which will increase the difficulty for later maintenance and debugging. Many PCB factories do not use black PCB very much. Even in the fields of military industry and industrial control, products with extremely high quality requirements use green PCB substrates.

Next, let’s talk about the effect of solder mask ink color on the board?

For the finished product, the influence of different inks on the board is mainly reflected in the appearance, that is, whether it is good or not. For example, green includes sun green, light green, dark green, matt green, etc., the color is too light, it is easy to see the plug The appearance of the board after the hole process is not good, and some manufacturers’ inks are not good, there is a problem with the ratio of resin and dye, there will be problems such as bubbles, and slight changes in color can also be detected; the impact on semi-finished products is mainly reflected In terms of the difficulty of production, this problem is a bit complicated to explain. Different color inks have different coloring processes, such as electrostatic spraying, spraying, and screen printing. The ink ratio is also different. A slight error will cause the color to appear. problem.

Although the color of the ink has no effect on the PCB board, the thickness of the ink has a great impact on the impedance, especially for the water-gold board, which has an extremely strict control on the thickness of the ink; the thickness and bubbles of the red ink are relatively easy to control, and the red ink is covered On the line, some defects can be covered, and the appearance is more beautiful, but the downside is that the price is more expensive. When imaging, red and yellow exposures are more stable, and white is the most difficult to control.
　
In summary, the color has no effect on the performance of the finished board, and has a relatively small impact on the PCB assembly and other links; in PCB design, every detail in each link is strictly controlled, and a PCB board becomes The key to a good board. PCB motherboards of different colors are mainly for product sales. It is not recommended that you use color as an important consideration in PCB processing.