PCB circuit board consists of what？

1. Pattern: the line is used as a tool for conduction between the original, in the design of the design will additionally design a large copper surface as the ground and power layer. Lines and patterns are made at the same time

2.Throughhole/via: Through hole can make more than two levels of line conduction with each other, the larger through holes are made for parts plug-in, in addition there are non-conductive holes (nPTH) is usually used as a surface mount positioning, fixed screws used in the assembly.

3. Solderresistant/SolderMask: not all copper surface to eat tin on the parts, so non-tin-eating areas, will be printed a layer of copper surface insulation to eat tin substances (usually epoxy resin), to avoid non-tin-eating short circuit between the lines. According to different processes, divided into green oil, red oil, blue oil.

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

5.Legend/Marking/Silkscreen: This is a non-essential component, the main function is to mark the name of each part on the circuit board, the location of the frame, to facilitate maintenance and identification after assembly.

6. SurfaceFinish: Due to the copper surface in the general environment, it is easy to oxidize, resulting in the inability to tin (solderability bad), so it will eat tin to protect the copper surface. The way of protection has HASL, ENIG, ImmersionSilver, Immersion TIn, OSP, the method has its own advantages and disadvantages, collectively known as surface treatment.