PCB is the basis of various electronic products and realizes multiple functions. So what parts does PCB consist of?
1.PCB layer
A standard PCB consists of multiple layers, each with a specific function. They are substrate, copper foil, solder mask, and screen printing.
Substrate:The substrate is the basic material that constitutes the PCB and is the support of the structure. Commonly used materials are FR-4, CEM-1, and polyimide. Among them, FR4 is the most common material, CEM-1 is a very cheap low-performance material, and polyimide is what everyone often calls a flexible PCB, which can be bent and folded.
Copper foil:The copper foil is laminated on the substrate to form the conductive layer of the entire circuit.
Solder mask:The solder mask is a protective layer applied to the copper traces to prevent short circuits and oxidation. It also provides insulation protection. The common material is liquid photosensitive epoxy (LPI), and the most common color is green, which is why most of the PCBs we see are green, and it also plays a role in determining the color of the PCB. The thickness is usually 20-30 µm.
Silkscreen:The silkscreen layer is used to print text and symbols on the PCB for component identification, test points and special markings.
2.Other components and parameters
Via: Vias are holes that pass through the PCB and are used to establish electrical connections between different layers. Common types are through-hole vias, blind vias, and buried vias.
Surface treatment: Surface treatment protects exposed copper and provides a solderable surface. Common surface treatments are HASL (hot air solder leveling), ENIG (electroless nickel immersion gold), OSP (organic solderability preservative)
Conclusion
The main components of PCBs are composed of multiple layers, which are mainly divided into four categories, namely substrate, copper foil, solder mask, and silkscreen.
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