What is the solder mask in PCB manufacturing

We all know that the solder pad refers to the part of the board that needs to be coated with solder mask ink, but in fact this solder mask layer uses a negative output, so after the shape of the solder mask layer is mapped onto the board, it is not the green ink solder mask Instead, the copper skin was exposed. Generally, in order to increase the thickness of the copper skin, the solder resist layer is scribed to remove green oil. The role of solder mask in controlling soldering defects during the reflow soldering process is important, and PCB designers should minimize the spacing or air gaps around the pad features. Why should we do solder mask? For the purpose of solder mask, I have listed the following points for you:

1. Leave the through holes and pads to be soldered on the board to cover all circuits and copper surfaces to prevent short circuit caused by wave soldering and save the amount of solder.

2. Prevent the invasion of moisture and various electrolytes to oxidize the circuit and harm the electrical performance, and prevent external mechanical damage to maintain good insulation of the board surface.

3. As the board becomes thinner and thinner and the line width becomes thinner and thinner, the insulation problem between the conductors becomes more prominent, and the importance of the insulation performance of the solder mask is also increased.

For the solder mask process, I don't think there will be too many changes, but the process innovation is everywhere, and the future development will encounter various challenges, challenges are everywhere. Manufacturers of materials, equipment, and PCBs will face tremendous pressure to challenge or even survive. Domestic PCB manufacturers are at a relatively disadvantaged position in HDI PCB, automotive boards, and IC carrier boards, and require more investment. Material suppliers, equipment manufacturers, and manufacturers are required to cooperate more closely than simply to buy and sell. Of course, different companies need different positioning of their products. They should not all develop towards HDI, automotive electronics PCB boards, and IC packaging substrates. For companies, the harder the better, the more sophisticated the better.