Number of layers: 4-32 layers
Board thickness: 0.38-5.5mm
Aspect ratio: 20:1
Minimum line width/line spacing:0.075mm/0.075mm,Surface treatment: Immersion gold, lead-free tin spray, OSP, Immersion tin, Immersion silver.
Main applications: automotive, medical, industrial control, communication IoT, photovoltaic, and other higher-end products.
Multi-Layer PCB is made by using multiple etched double-sided boards, laminated with an insulation layer (Prepreg) between the boards, and the outermost two sides are laminated with copper foil and pressed together. Since multiple double-sided panels are pressed together, the number of layers is usually an even number. The copper foil layer being pressed inside can be a conduction layer, a signal layer, a power layer, or a ground layer. Multilayer boards can have more than 40 layers, but the maximum practical application is currently about 30 layers. Multilayer boards can make the most number of copper conductors, used in more complex circuits, the current computer motherboard used due to too many components, most use eight-layer board, general small electronic products, such as cell phones, tablet PCs, etc. due to the requirements of the small size, at least eight layers of the board, the more electronic components, the smaller the size of the product, usually requires more layers of PCB.
FR-4 (Fiberglass Epoxy Substrate) is the most widely used material in the global electronics industry. FR is a code for a flame-resistant material grade, which means that the resin material must be able to extinguish itself after burning. However, most of the FR-4 grade materials are made of four-function epoxy resin, filler and glass fiber. In recent years, due to the development of electronic installation technology and PCB technology, there are FR-4 products with high Tg degree (Glass Transition Temperature).
Example: S1141, IT180, Rogers 4350B, etc.