7 Ways to Quickly Judge the Quality of Circuit Board Design (Part 5)

5-Component placement

In addition to placing decoupling capacitors, there are other precautions for placing components on the circuit board. Here are some notes: If the circuit contains inductors, they should not be placed too close. The inductance generates a magnetic field. Placing them closely together, especially end-to-end connection may cause unnecessary coupling between them. In addition, inductors should not be placed close to large metal objects.

The magnetic field induces current in these objects, which changes the value of the inductor. Ring or toroidal inductors are usually not prone to generate stray magnetic fields, so their influence is small. If it is unavoidable to place the inductors close together, they should be placed perpendicular to each other to reduce unnecessary mutual coupling. If the board contains power resistors or any components that generate a lot of heat, you need to consider the effect of heat on other nearby components.

For example, if the thermistor is included in the circuit to compensate for ambient temperature effects, it should not be placed close to any power resistors. The same is true for temperature compensation capacitors. If the circuit contains an on-board switching regulator, all components related to it should be physically located on a part of the PCB and as far away as possible from the part that handles small signals.

These tend to generate a lot of switching noise, which may have a negative impact on sensitive circuit parts. If the PCB usually directly applies AC power to it in the power section, the AC side should be located on a part of the circuit board. In addition, the PCB itself should have a physical barrier to separate the AC from the rest of the board. Usually, this is achieved by having a slot in the PCB that separates the two parts.