Why use serpentine routing in PCB layout?
Why use serpentine routing in PCB layout?
The main reasons for using serpentine routing in PCB layout are as follows:
Signal integrity protection:
1.Reduce signal reflection: By adjusting the wire width and copper foil thickness, more accurate impedance matching can be achieved, thereby reducing signal reflection and distortion.
2.Reduce signal crosstalk: Serpentine routing can also reduce crosstalk between adjacent signal paths and improve the quality of signal transmission.
3.Delay matching and synchronization control: In complex high-speed digital circuits, the signal transmission speed of different paths may vary due to factors such as line length, line width, and copper foil thickness. Serpentine routing can ensure that key signals such as clock signals and synchronization signals have the same delay by precisely controlling the line length, meeting the timing design requirements of the system.
Improvement of electromagnetic compatibility:
1.Reduce electromagnetic interference: Serpentine routing reduces the chance of direct coupling by increasing the distance between routings, thereby reducing electromagnetic interference.
2.Disperse radiated energy: Serpentine routing can also disperse radiated energy, further reducing the impact of electromagnetic interference.
Thermal management and space utilization:
1.Conducive to heat dispersion: Due to its large surface area, serpentine traces help to disperse heat, thereby reducing the possibility of hot spots to a certain extent and improving the thermal stability of the circuit board.
2.Effective use of space: There are often some irregular blank areas in the PCB layout. Serpentine traces can better fill these blanks, effectively utilize the PCB surface, and improve space utilization.
Unique advantages in special applications:
1.As a filter inductor: In some designs, serpentine traces can be used as filter inductors to help filter out high-frequency noise and improve the anti-interference ability of the circuit.
2.For on-board antennas: In on-board antenna design, serpentine traces are often used as part of the antenna to achieve cost-effective antenna integration.
3.Similar to the role of a fuse: Serpentine traces can also limit the current passing through it through a specific design, thereby playing a protective role similar to a fuse.
Although the advantages of serpentine routing are obvious, there are also some disadvantages:
Signal integrity issues:
1.Increase signal crosstalk: Coupling will occur between the parallel segments in the serpentine routing, in the form of differential mode. The degree of coupling is related to the parallel coupling length and coupling distance. The smaller and larger the coupling, the greater the degree of coupling, which may greatly reduce the quality of the signal.
2.Cause signal transmission delay: The curved routing will increase the transmission distance of the signal, especially at high frequencies, the signal attenuation is more obvious, which may cause signal quality to deteriorate and affect system performance.
3.Electromagnetic compatibility issues: Due to its curved shape, the serpentine line is prone to form an antenna effect, increase electromagnetic radiation, and may interfere with surrounding signals or be interfered with by other signals, causing signal integrity problems.
Increased design and manufacturing difficulty:
1.Increased design complexity: A well-designed serpentine line requires careful calculation to ensure the equal length effect, which increases the design complexity. More factors need to be considered in the design process, such as the length of the line, the degree of curvature, the spacing, etc., which requires designers to have higher expertise and experience.
2.Increased manufacturing costs: Complex routing layouts may lead to higher PCB manufacturing costs because it may require more layers, more sophisticated manufacturing processes, and higher quality control requirements. In addition, serpentine wiring may increase the difficulty of wiring, resulting in longer wiring time, thereby increasing production costs.
3.Difficult maintenance and upgrade: The complex layout of the serpentine line makes subsequent maintenance and system upgrades more difficult, especially when the signal line needs to be modified or added, the entire layout may need to be readjusted, which will take a lot of time and effort.
4.Inefficient space utilization: Although serpentine wiring can increase the length of the wiring to a certain extent, in some cases it may take up more space, resulting in an increase in the area of the PCB. This may be a disadvantage for product designs with limited space.
