PCB Fabrication

Precautions for PCB wiring

by:A-TECH      2021-03-15
•While designing the printed circuit board of the logic circuit, the ground wire should form a closed-loop form, which can effectively improve the anti-interference ability of the circuit. • The ground wire should be as thick as possible. We all know that a thin wire has a large resistance, and a large resistance will cause the ground potential to change with the current. This will cause the signal level to be unstable, and then the circuit's anti-interference ability will decrease. • Pay attention to the choice of grounding point. When the signal frequency on the circuit board is lower than 1MHz, because the electromagnetic induction between the wiring and the components has little effect, and the circulation formed by the grounding circuit has a greater influence on the interference, it is necessary to use a point grounding so that it does not form a loop. When the signal frequency on the circuit board is higher than 10MHz, due to the obvious inductance effect of the wiring, the ground impedance becomes very large. At this time, the circulating current formed by the ground circuit is no longer a major problem. Therefore, multi-point grounding should be used to minimize the ground impedance. • In addition to the layout of the power line, the width of the trace should be as thick as possible according to the size of the current. When wiring, the routing direction of the power line and the ground line should be consistent with that of the data line. At the end of the wiring work, use the ground Lines cover the bottom of the circuit board where there are no traces. These methods all help to enhance the anti-interference ability of the circuit. • The width of the data line should be as wide as possible to reduce impedance. •The number of vias should be reduced as much as possible. It is important to know that a via on the circuit board will bring about a capacitance effect of about 10pF. This interference is very large in high-frequency circuits, so the number of vias should be reduced as much as possible. Furthermore, too many vias are still Will cause the mechanical strength of the circuit board to be greatly reduced.
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