General Principles of Component Routing

PCB component routing is a crucial phase in circuit design, significantly influencing the performance, stability, and production cost of the final product. A well-planned layout not only reduces trace length and minimizes signal delay but also helps lower electromagnetic interference (EMI) and improves the board's overall anti-interference capability. Additionally, it plays a key role in optimizing heat dissipation, preventing overheating issues that could damage components or reduce reliability.

During the routing process, designers must consider more than just electrical performance. Mechanical constraints, manufacturing limitations, and assembly requirements should also be taken into account. Below are some essential routing principles to follow:

1. Spacing Between Networks: The distance between different network traces depends on factors like electrical insulation, manufacturing capabilities, and component size. It’s important to ensure sufficient clearance, especially when high-voltage and low-voltage circuits coexist on the same board. Proper spacing prevents short circuits and ensures long-term reliability.
2. Routing Corner Design: To improve manufacturability and aesthetics, routing corners should be designed with 45°, 90°, or arc-shaped turns rather than sharp angles. This avoids stress points on the copper traces and reduces the risk of cracking during production. Also, the connection between a wire and a pad should be smooth, avoiding any sharp edges that might cause problems during soldering or inspection.
3. Trace Width Selection: Trace width is determined by current capacity and noise immunity. Higher current lines require wider traces to prevent overheating and voltage drop. Power and ground lines, in particular, should be wider to maintain stable voltage levels and reduce resistance. When space allows, increasing the width of these lines can enhance signal integrity and reduce EMI.
4. Interference and Shielding: Interference from adjacent traces, power lines, and crosstalk between signals can degrade performance, especially in high-speed designs. Proper layout, such as keeping sensitive signals away from noisy ones, and using grounding techniques can help minimize this. For critical signals like clock lines, shielding with a ground loop around them is highly effective in reducing external noise and improving EMC performance.
5. Via Usage: Each via introduces parasitic capacitance, which can be problematic in high-speed circuits. Excessive vias may also weaken the mechanical structure of the board. Therefore, it's best to use as few vias as possible. If through-hole vias are necessary, it's common practice to use pads instead, as they are more reliable during the drilling process and less likely to result in manufacturing defects.

These guidelines provide a solid foundation for PCB routing, but real-world applications often require flexibility and judgment based on specific project needs. While following these rules can lead to better performance and reliability, practical experience remains the ultimate test of a designer’s skill.