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What is a 2-layer PCB?


Published by: KEYOU PCB November 20,2023

The 2 layer PCB refers to copper foil on both sides and has metallized holes. There are wiring on both sides of the 2 layer PCB, but to use the wires on both sides, it is necessary to have proper circuit connections between the two sides. The "bridge" between such circuits is called a via. The via hole is a small hole filled or coated with metal on the pcb, which can be connected to the wires on both sides. Because the area of ​​the 2 layer PCB is twice as large as that of the single-panel, the double-panel solves the difficulty of wiring interleaving in a single panel (it can be conducted through the hole to the other side), which is more suitable for circuits that are more complicated than single-panel.


                 What is a 2-layer PCB?


2 layer PCB advantages
Advantages (compared to single-layer boards): Convenient wiring, simple wiring, less labor intensity and shorter line length.


2 layer PCB board routing skills
Automated routing does not have problems with purely digital circuits (especially low frequency signals and low density circuits). However, when attempting to use the automatic routing tool provided by the cabling software for wiring analog, mixed signal or high-speed circuits, some problems may occur and may cause extremely serious circuit performance problems. There are many things to consider about wiring, but the more troublesome issue is the grounding method. If the ground path begins with the upper layer, the ground of each device is connected to the ground via a pull wire on the layer. For each device of the lower layer, it is connected to the upper layer by a through hole on the right side of the circuit board to form a ground loop. The immediate red flag that the user sees when checking the wiring pattern indicates that there are multiple ground loops. In addition, the ground loop of the lower layer is at a level. It can reduce the effect of digital switching δi/δt on analog circuits. However, it should be noted that the two double-layer boards have a ground plane on the lower layer of the board. This is designed so that engineers can quickly see the wiring when troubleshooting, which is often seen on the device manufacturer's demonstration and evaluation board. But a more typical approach is to lay a ground plane on the upper layer of the board to reduce the electromagnetic dry (emi).

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