General Principles of Component Routing

PCB component routing is a critical step in circuit design, directly impacting the performance, stability, and production cost of the circuit. A reasonable layout of components can reduce trace length, minimize signal delay, reduce electromagnetic interference, and improve the circuit's anti-interference capability. Additionally, it can optimize heat dissipation and reduce the heating issues on the circuit board. During the component routing process, not only electrical performance must be considered, but also mechanical structure and manufacturing processes. Below are some common routing principles:

1. The spacing constraints between different networks are determined by factors such as electrical insulation, manufacturing processes, and component size. In addition, spacing settings must take into account the manufacturer's production capabilities. Another important factor affecting components is electrical insulation. If there is a large potential difference between two components or networks, electrical insulation must be considered, especially when both high-voltage and low-voltage circuits exist on the same circuit board, where special attention must be given to ensure adequate safety clearance.
2. The choice of routing form for circuit turns: To make the circuit board easier to manufacture and aesthetically pleasing, the cornering mode of the routing should be set during design. Options include 45°, 90°, and arcs, with sharp corners generally avoided. The connection between the wire and the pad should also be as smooth as possible to prevent small sharp points from appearing. When a wire passes between two pads without connecting to them, it should maintain the maximum and equal distance from both pads. Similarly, the spacing between wires should be evenly equal and maximized.
3. The determination of trace width: Trace width is determined by factors such as the current level passing through the wire and interference resistance. The greater the current, the wider the trace should be. In general, power lines should be wider than signal lines. To ensure the stability of the ground potential (minimizing the impact of ground current variations), the ground line should also be wider. To ensure the peel strength and operational reliability of the wires, the widest possible traces should be used within the allowable board area and density to reduce circuit impedance and improve interference resistance.For the width of power and ground lines, to ensure waveform stability, they should be thickened as much as possible when routing space allows. Typically, a minimum width of 50 mil is required.
4. Interference and electromagnetic shielding of printed circuit traces: The interference on the traces mainly includes interference introduced between traces, interference from power lines, and crosstalk between signal lines. Proper arrangement and layout of the traces, as well as grounding methods, can effectively reduce interference sources and enhance the electromagnetic compatibility (EMC) performance of the designed circuit board. For high-frequency or other critical signal lines, such as clock signal lines, the trace should be as wide as possible. Additionally, shielding can be applied by enclosing the signal line with a ground line (essentially wrapping the signal line with a closed ground line), which acts as a grounding shield layer, isolating it from surrounding signal lines.
5. For high-frequency or other critical signal lines, such as clock signal lines, the trace should be as wide as possible. Additionally, shielding can be applied by enclosing the signal line with a ground line (essentially wrapping the signal line with a closed ground line), which acts as a grounding shield layer, isolating it from surrounding signal lines.
6. A single via on a circuit board introduces approximately 10pF of parasitic capacitance, which is especially harmful in high-speed circuits. Additionally, excessive vias can reduce the mechanical strength of the circuit board. Therefore, when routing, the number of vias should be minimized as much as possible. Moreover, when using through-hole vias, pads are typically used as a substitute. This is because, during the manufacturing process, certain through-hole vias may not be drilled completely due to processing errors, whereas pads are guaranteed to be drilled through, thus making the manufacturing process more reliable.

The above are general principles for PCB routing, but in practice, the routing of components is still a very flexible process. Therefore, the above routing principles serve only as design guidelines, with practice being the only true measure of their effectiveness.