PCB Design Considerations: Placement and Routing Techniques

Introduction

Printed Circuit Boards (PCBs) are a crucial component of modern electronics, and their design plays a significant role in determining the overall performance and reliability of a system. In this lecture, we will explore the key considerations for PCB design, focusing on placement and routing techniques.

“DIY Printed Circuit Board” by kjackman is licensed under CC BY-SA 2.0.

Placement Techniques

Component placement is a critical aspect of PCB design, as it directly affects the performance, reliability, and manufacturability of the board. Here are some key placement techniques to consider:

1. Component Placement Guidelines: Components should be placed in a way that minimizes signal interference, thermal issues, and difficulties in assembly and testing.
2. Floor Planning: The floor plan of the PCB should be carefully designed to ensure that components are placed in a logical and efficient manner.
3. Component Placement Order: Components should be placed in a specific order, starting with the most critical components, such as connectors and main functional chips.

Routing Techniques

Routing is another critical aspect of PCB design, as it directly affects the performance and reliability of the board. Here are some key routing techniques to consider:

1. Autorouting: Autorouters can be used to save time and effort in routing, but they should not be relied upon entirely.
2. Manual Routing: Manual routing is often necessary to ensure that the routing is done correctly and efficiently.
3. Trace Width and Spacing: Trace width and spacing are critical factors in determining the performance and reliability of the board.
4. Ground and Power Traces: Ground and power traces should be carefully designed to ensure that they are properly connected and do not interfere with other signals.
5. Thermal Vias and Pads: Thermal vias and pads should be used to dissipate heat and ensure that the board operates within a safe temperature range.

Best Practices

Here are some best practices to keep in mind when designing a PCB:

1. Avoid 90° Angles: 90° angles should be avoided in routing, as they can cause signal reflections and other issues.
2. Use Ground and Power Planes: Ground and power planes should be used to provide a solid reference point for measuring voltages and to reduce noise immunity.
3. Keep Enough Space between Traces: Enough space should be kept between traces and pads to avoid short circuits and other issues.
4. Alternate Trace Direction: Trace direction should be alternated to reduce crosstalk and other signal integrity issues.

References

1. MCL. (n.d.). Top 10 Best Practices for PCB Routing. Retrieved from https://www.mclpcb.com/blog/pcb-routing-best-practices/
2. Proto-Electronics. (n.d.). Our Top 10 PCB Routing Tips. Retrieved from https://www.proto-electronics.com/blog/top-10-pcb-routing-tips
3. Candor Industries. (n.d.). PCB Design Considerations: Placement and Routing Techniques. Retrieved from https://www.candorind.com/pcb-design-considerations-placement-routing-techniques/
4. Sierra Circuits. (n.d.). Component Placement in PCB Design & Assembly. Retrieved from https://www.protoexpress.com/blog/component-placement-guidelines-pcb-design-assembly/
5. Cadence. (n.d.). Basic PCB Component Placement Guidelines. Retrieved from https://resources.pcb.cadence.com/blog/2022-basic-pcb-component-placement-guidelines