The green part is called solder resist. These components are resins and pigments, and the green part is green pigments, but with the development of modern technology, many other colors have been extended. It is no different from decorative paint. Solder mask is pasted and flowed before soldering is printed on the board. After printing on a circuit board, the resin hardens due to heat and eventually "cures". The purpose of resistance welding is to protect the circuit board from moisture, oxidation and dust. The only place not covered by solder mask is usually called the pad and is used for solder paste.
Generally speaking, we choose green because it does not irritate the eyes, and it is not easy for production and maintenance personnel to stare at the PCB for a long time. In terms of design, commonly used colors are yellow, black and red. All kinds of colors are paints sprayed on the surface after manufacture.
Another reason is that the commonly used color is green, so the factory has the most spare green paint, so the cost of oil is relatively low. This is also because when repairing the PCB board, different wiring is easier to distinguish from white, while black and white are relatively difficult to see. In order to distinguish its product grades, each factory uses two colors to distinguish high-end series from low-end series. For example, Asustek, a computer motherboard company, has a yellow board for the low end and a black board for the high end. Yingtai's rebounds are high-end, while green boards are low-end.
1. There are signs on the circuit board: the beginning of R is resistance, the beginning of L is inductance coil (usually the coil is wound on the iron core ring, some shells are closed), the beginning of C is capacitor (tall cylindrical, made of plastic Leather package, electrolytic capacitors with cross indentations on it, flat chip capacitors), the other two legs are diodes, three legs are triodes, and many legs are integrated circuits.
2. Silicon controlled rectifier UR; rectifier VC with power supply for control circuit; frequency converter UF; converter UC; inverter UI; motor M; asynchronous motor MA; synchronous motor MS; DC motor MD; wound rotor induction motor MW; squirrel cage motor MC; electric valve YM; solenoid valve YV, etc.
3. Extended reading Attached is part of the component name marking information on the motherboard circuit board with diagrams.
This is the reason why the board is green, I hope it can provide you with some reference!
