As the name suggests, a multilayer circuit board can be called a multilayer circuit board with more than two layers, such as four layers, six layers, eight layers and so on. Of course, some designs are three-layer or five-layer circuits, also called multilayer PCB circuit boards. For conductive traces larger than two-layer boards, there is an insulating base material between the layers. After each layer of wiring is printed, it is laminated to overlap each layer of wiring. Drill holes afterwards, and realize the conduction between the lines of each layer via holes.
Multilayer PCB boards are an inevitable product of the development of electronic technology in the direction of high speed, multi-function, large capacity and small volume. With the continuous development of electronic technology, especially the extensive and in-depth application of large-scale and very large-scale integrated circuits, multilayer printed circuits are rapidly developing in the direction of high density, high precision, and high-level digitalization. Technologies such as fine lines, small aperture penetration, and high plate thickness/aperture ratio for blind holes and buried holes have emerged to meet the needs of the market.
The advantage of the multilayer PCB board is that the circuit can be distributed in the multi-layer wiring, so that more precise products can be designed. Or smaller products can be realized by multi-layer boards, such as: mobile phone circuit boards, micro projectors, voice recorders and other products with relatively large volumes. In addition, multi layers can increase the flexibility of design, can better control the differential impedance and single-ended impedance, as well as the output of some signal frequencies.
Due to the needs of the computer and aerospace industries for high-speed circuits, further increases in packaging density are required, coupled with the reduction in the size of separate components and the rapid development of microelectronics, electronic equipment is developing in the direction of shrinking volume and reducing weight; Due to the limited space available for printed boards, it has been impossible for single and double sided PCB boards to achieve a further increase in assembly density. Therefore, it is necessary to consider using printed circuits with multilayers than double-sided boards. This creates conditions for the emergence of multilayer circuit boards.