1. Circuit and Pattern: the circuit serves as a tool for conducting between the original components, and a large copper surface will be designed as the grounding and power layer in the design. The line and the drawing are made at the same time.

Dielectric layer (Dielectric) : used to maintain the line and the insulation between the layers, commonly known as the substrate.

3. Through hole/via: the through-hole can make two or more layers of circuit conduct each other, the larger through-hole is used as part plug-in, in addition, there is a non-through-hole (nPTH) is usually used as a surface mount positioning, assembly screws used.

4. Solder resistant /Solder Mask: not all copper surfaces are resistant to tin parts; therefore, in areas that are not resistant to tin, a layer of material (usually epoxy resin) that is resistant to tin will be printed to prevent short-circuit between non-resistant lines. According to different processes, it can be divided into green oil, red oil and blue oil.

5. Legend /Marking/Silk screen: this is not necessary. The main function is to mark the name and location frame of each part on the circuit board, which is convenient for maintenance and identification after assembly.

6. Surface Finish: as the copper Surface is easy to oxidize in the general environment, it cannot be tinned (poor solderability), so it will be protected on the copper Surface that needs tin. Protection methods have spray TIn (HASL), ENIG (ENIG), Immersion Silver (Immersion TIn), organic Immersion TIn (OSP), each method has advantages and disadvantages, collectively known as surface treatment.

Characteristics of PCB

1. High density: over the decades, the high density of printed board can be developed with the improvement of integrated circuit integration and installation technology progress.

2. High reliability: through a series of inspection, test and aging test, PCB can be guaranteed to work reliably in the long term (the service life is generally 20 years).

3. Designability: for PCB’s various performance requirements (electrical, physical, chemical, mechanical, etc.), it can realize PCB design through design standardization, standardization, etc. with short time and high efficiency.

4. Productivity: modern management can be adopted to standardize, scale (quantity) and automate production to ensure product quality consistency.

5. Testability: relatively complete test methods, test standards, various test equipment and instruments are established to detect and identify the PCB product qualification and service life.

Assemblability: PCB products are not only convenient for standardized assembly of various components, but also can be automated and mass-produced on a large scale. At the same time, PCB and various component assembly parts can be assembled to form larger parts, systems, and even the whole machine.

6. Maintainability: PCB products and various component assembly parts are standardized in design and large-scale production, so they are also standardized. Therefore, in case of system failure, it can be replaced quickly, conveniently and flexibly to restore the system to work quickly. Of course, there are more examples. Such as the system miniaturization, lightweight, high-speed signal transmission and so on.