The difference between 2-layer PCB and 4-layer PCB processed by SMT

Different PCB layer

Abstract: In daily smt processing, our basis is PCB, that is, printed circuit board (PCB). Their specific differences are distinguished by the number of layers, such as the 2-layer PCB board and the 4-layer pcb board. At present, it can achieve up to 48 layers. From a technical point of view, the number of layers has unlimited possibilities in the future. Some supercomputer structures have nearly a hundred layers, but the most common layered PCBs in medical electronics PCBA or automotive electronics usually have only 2 or 4 layers. If you want to choose your board layers reasonably, please understand the difference between 2-layer and 4-layer boards before making a decision!

2-layer PCB

Compared to a 4-layer PCB, a 2-layer PCB is easier to work with due to its simple design. While not as simple as a 1-layer PCB, they are as simple as possible without sacrificing double-sided input capability. Reduced complexity results in an equally reduced price tag, but that means fewer possibilities than with a 4-layer PCB. However, as the industry’s most common board, it has the distinct advantage of having no propagation delay in the signal.

4-layer PCB

A 4-layer PCB has a larger surface area than a 2-layer PCB, increasing the possibility of more wiring. As such, they are ideal for more complex devices. Due to their complexity, they will be more expensive to produce and slower to develop. They are also more likely to exhibit propagation delays or mutual influence, so a reasonable design is very important.

So what are PCB layers for?

The most important layer in the PCB is the copper foil signal layer, which is the name of the PCB. While a 2-layer PCB has two signal layers, a 4-layer PCB has four. These signal layers are used to connect to other electronic components in the device. Between these layers is an insulating layer or core, which is added between the signal layers to give it structure. In a 4-layer PCB, there is also a solder mask here, which is applied on top of the signal layer. This prevents the copper traces from interfering with other metal components on the PCB. They also have a silkscreen layer for adding numbers to the different components to make them easier to lay out.

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