pcb classification

pcb two classification methods do you know?

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Classification by number of floors

According to the number of layers of circuit classification: divided into single-sided, double-sided and multilayer boards. Common multilayer boards are generally 4-layer boards or 6-layer boards, complex multilayer boards can reach dozens of layers. PCB boards have the following three main types of division.

Single Panel

Single-Sided Boards In the most basic PCB, the parts are concentrated on one side, and the wires are concentrated on the other side (with SMD components and wires on the same side, and plug-in devices on the other side). Because the wires only appear on one side, so this PCB is called single-sided (Single-sided). Because the single-sided board in the design of the line has many strict limitations (because only one side, the wiring can not cross between and must be wrapped around a separate path), so only the early circuit use this type of board.

Double Panel

Double-Sided Boards This type of board has wiring on both sides, but in order to use the wires on both sides, there must be a proper circuit connection between the two sides. This circuit between the “bridge” is called a guide hole (via). Guide holes are in the PCB, filled or coated with metal holes, which can be connected to the two sides of the wire. Because the double-sided panel is twice as large as the single-sided panel, the double-sided panel solves the difficulty of interlacing the wiring in the single-sided panel (you can pass through the hole to the other side), it is more suitable for use in more complex circuits than the single-sided panel.


Multi-Layer Boards In order to increase the area that can be wired, multiple-layer boards use more single- or double-sided wiring boards. Using a double-sided as the inner layer, two single-sided as the outer layer or two double-sided as the inner layer, two single-sided as the outer layer of the printed circuit board, through the positioning system and insulation bonding material alternate together and conductive graphics according to the design requirements of the interconnection of the printed circuit board will become a four-layer, six-layer printed circuit boards, also known as multilayer printed circuit boards.

pcb classification

The number of layers of the board does not mean that there are several separate wiring layers, in special cases will add empty layers to control the thickness of the board, usually the number of layers are even, and includes the outermost two layers. Most mainframe boards are 4 to 8-layer structure, although technically it is possible to do nearly 100 layers of PCBs in theory. Large supercomputers mostly use quite a few layers of motherboards, although because such computers can already be replaced by many clusters of ordinary computers, ultra-layer boards have gradually fallen out of use. Because the layers in the PCB are tightly integrated, it is generally less easy to see the actual number, but if you look closely at the motherboard, you can still see.

Classification by soft and hard

Divided into rigid circuit boards and flexible circuit boards, rigid and flexible boards. The general PCB shown in the first picture below is called rigid (Rigid) PCB, the second picture in the yellow connection line called flexible (or perturbative Flexible) PCB. rigid PCB and flexible PCB is the intuitive difference is that the flexible PCB can be bent.

The common thickness of rigid PCBs are 0.2mm, 0.4mm, 0.6mm, 0.8mm, 1.0mm, 1.2mm, 1.6mm, 2.0mm, etc. The common thickness of flexible PCB is 0.2mm, and where the parts are to be soldered, a thickening layer is added behind it, and the thickness of the thickening layer varies from 0.2mm to 0.4mm. The purpose of understanding these is to provide structural engineers with a space reference when designing them.

The common materials of rigid PCB include: phenolic paper laminate, epoxy paper laminate, polyester glass mat laminate, epoxy glass cloth laminate; the common materials of flexible PCB include: polyester film, polyimide film, fluorinated ethylene propylene film.

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