What’s the effect of solder resist color to the PCB?

The PCB board is not the more colorful, the more useful.

Actually, the color of PCB board surface is the color of solder mask. First, the solder resist can prevent the wrong soldering of the components. Second, it can delay the service life of the devices, so as to prevent the oxidation and corrosion of the circuit.

If you know more about the PCB board of HUAWEI, Ericsson and other large companies, you will find that the color is generally green. Because the green color technology for PCB board is the most mature and simple.

Except green, there are many colors of PCB, such as: white, yellow, red, blue, sub light color, and even chrysanthemum, purple, black, bright green, etc. The white is the necessary pigment for the production of lamps and lanterns. The use of other colors is mostly for the purpose of labeling products. The PCB making company’s products from R&D to maturity of the whole stage, according to the different uses of PCB board, the experimental board may use purple, the key board will use red, the computer internal board will use black, all of which are to distinguish and mark by color.

The most common PCB is green board, also known as green oil, and its solder resist ink has the longest history, cheapest and most popular. Green oil has many advantages besides mature technology:

In PCB processing, the production of electronic products includes plate making and lamination. During this period, there are several processes to go through the yellow light room, and the green PCB board has the best visual effect in the yellow light room. Secondly, in the SMT PCB board, the steps of tinning, lamination and AOI verification all need optical positioning and calibration, and the green PCB is better in instrument identification.

Part of the inspection process depends on the observation of workers (now most of them use flying needle test instead of manual work). They keep staring at the board under strong light, and the damage of green to eyes is relatively low. The green PCB board is more environmentally friendly, and after high temperature recycling, it will not release toxic gases.

The other colors of PCB, such as blue and black are doped with cobalt and carbon respectively. Because of they are weak conductive, there is a risk of short circuit.

Such as the black board, it is most likely to cause color difference due to process and raw material problems in production, which leads to high PCB defect rate. The routing of black circuit board is not easy to identify, which will increase the difficulty of later maintenance and debugging. Therefore, many PCB assembly manufacturers did not use black PCB board. Even in the field of military industry and industrial control, products with high quality requirements also use green PCB board.

What is the effect of solder resist ink color on the PCB board?

For finished products, the impact of different inks on the board is mainly reflected in the appearance. For example, green includes sun green, light green, dark green, matte green and so on. If the color is too light, After the plug hole process, the appearance of the board will be obvious. Some manufacturers have poor inks, resin and dye ratio problems, and there will be bubbles and other problems Detect slight color changes. For semi-finished products, the impact is mainly reflected in the degree of difficulty in production. This questions is a bit complicated to explain. The different color inks have different coloring processes, including electrostatic spraying, spraying and screen printing, and the ink ratio is also different. If there is a slight error, the color will go wrong.

Although the ink color has no influence on PCB board, the ink thickness has a great influence on impedance. Especially for water gold board, it controls the thickness of ink very strictly. The red ink, thickness and bubbles are relatively easy to control, and red ink can cover some defects on the circuit, which is more better in appearance, but the disadvantage is that the price is more expensive. When imaging, the red and yellow exposures are more stable, and white is the worst to control.

In summary, color has no influence on the performance of the finished board, and has little influence on SMT PCB board and other links. In PCB design, strictly controlling every detail in each link is the key to a good PCB board. Different colors of PCB board, mainly for the better look of the product, we don’t recommend color as an important factor in PCB processing.