6-Trace Width and Routing: Adjusting trace sizes appropriately is crucial especially for traces carrying large currents. Figure 2 below illustrates the recommended trace width by IPC (Printed Circuit Research Institute) for different rated currents. To avoid noise interference, analog signal traces should not run parallel to digital or rapidly changing signal traces.

7-Ground and Ground: For moderately complex PCBs, it is recommended to use at least a four-layer board, with two inner layers dedicated to power and ground. In designs with both analog and digital components, the ground plane should be separated and connected only at a common point, typically the negative terminal of the power supply. This prevents large ground current spikes from affecting the analog portion negatively. If only two layers are used, it is vital to separate the ground return traces of each sub-circuit and connect them all to the negative terminal of the power supply. Connecting the ground loop of any sub-part or IC to a common ground loop path and then returning it to the power supply’s negative terminal, as shown in Figure 3 below, is considered poor design practice. This arrangement causes voltage drops across the PCB traces due to their resistance, resulting in deviations in ground reference voltage and undesirable ground bouncing.

In conclusion, whether you are learning to design your own PCB or considering outsourcing it to an electrical engineer, it is essential to assess the quality of the PCB design. If you lack design experience and choose to outsource, be sure to evaluate the design based on the seven highlighted aspects in this article to determine if your engineer meets the standards. If any of these criteria are not met, it may be best to search for a new designer. Conversely, if you plan on designing your own PCB, be vigilant in avoiding these common mistakes. Additionally, it is always wise to have a thorough design review conducted by an independent engineer before proceeding with PCB fabrication and development.