Selection of Circuit Board

The primary task of PCB design is to properly select the size of the circuit board. Because the connection between components is too long, the impedance of the line increases and the anti-interference ability decreases. Is not conducive to heat dissipation, and the line is too thin and dense, easy to cause crosstalk. Therefore, the appropriate size of the circuit board should be selected according to the need of the system components.

The circuit board is divided into a single panel, double panel and multilayer board. The selection of circuit board layer number depends on the function, noise index, signal and network number of the circuit. Reasonable layer number setting can reduce the EMC problem of the circuit itself. The usual selection principle is:

(1) When the signal frequency is medium and low frequency, the components are less, and the wiring density is low or medium, one side board or two panel is chosen;

(2) The multilayer board is used when the wiring density is high, the integration is high and the components are more;

(3)For high signal frequency, high speed integrated circuits, components of the dense selection of 4 layers or more layers of circuit boards. The multilayer board can be used as a power layer, a signal layer and a grounding layer when it is designed. The area of the signal loop is reduced, and the differential mode radiation is reduced. For this reason, the multilayer board can reduce the radiation of the circuit board and improve the anti-interference ability.