The current circuit board is mainly composed of the following:
1. Line and Pattern: The line is used as a tool for conducting between the originals. The design will additionally design a large copper surface as the grounding and power plane. The line and the drawing are made at the same time.
2. Dielectric: Used to maintain the insulation between the circuit and the layers, commonly known as the substrate.
3. Through hole / via: The via hole can make the two levels above the line conduct each other, the larger via hole is used as the part plug, and the non-via (nPTH) is usually used as the Surface mount positioning, fixing screws for assembly.
4. Solder resistant /Solder Mask: Not all copper surfaces should be eaten on tin. Therefore, in areas where tin is not eaten, a layer of tin-plated tin (usually epoxy) is printed. To avoid short circuits between lines that are not tinned. According to different processes, it is divided into green oil, red oil and blue oil.
5. Legend / Marking / Silk screen: This is a non-essential structure. The main function is to mark the name and position frame of each part on the circuit board to facilitate post-assembly maintenance and identification.
6. Surface Finish: Since the copper surface is easily oxidized in the general environment, it is impossible to apply tin (poor solderability), so it will be protected on the copper surface to be tinned. The protection methods include spray coating (HASL), gold (ENIG), silver (Immersion Silver), tin (Immersion TIn), and organic solder resist (OSP). The methods have their own advantages and disadvantages, collectively referred to as surface treatment.