Procedure and Tips for Board Layout

PCB Layout & Routing
PCB design or CAD programs offer powerful capabilities, but the best results come from applying a structured design process. PCB Design Includes:

PCB design basics
Schematic capture & drawing
PCB layout & routing
PCB design guidelines
PCB signal integrity

PCB design programs provide extensive capabilities for handling boards with thousands of components and tracks. To make the most of these tools, a robust process is essential to meet all requirements and ensure optimal PCB performance.

By combining software power with sound design practices and appropriate constraints, you can achieve outstanding results.

PCB Layout Steps

Follow these steps in any PCB design:

Set up initial editor settings
Configure snap and visible grids, units, and enable any additional tools or add-ons needed for the workflow (such as those for KiCad).
Define PCB stack-up and design rules
Determine the board stack-up, including the number of layers, copper thicknesses, board thickness, and dielectric materials based on electrical and mechanical requirements. Define design rules such as clearances, trace widths, via sizes, and routing constraints.
Import or define a board template
Load an existing layout template or create one from scratch based on your project specifications, in both scenarios incorporating your stack-up and established design rules.
Define mechanical elements
Use the template outline if applicable, or draw the PCB outline manually. Add reference marks, mounting holes, and keep-out zones required for pick-and-place machines, test fixtures, or final enclosure integration.
Place critical and mechanical components first
Begin placement with mechanically critical components such as connectors, switches, mounting hardware, and other fixed-position items. At this point it is wise to temporarily hide silkscreen and fabrication layers to reduce visual clutter during placement and routing.
Group components into functional blocks
Arrange related components in logical clusters to simplify routing. Position and orient component pads to form clean lines or clusters that minimize trace lengths and reduce or eliminate trace crossings.
Route critical tracks
Identify and route layout-critical nets first (e.g., high-speed signals, differential pairs, analog signals), ensuring optimal signal integrity. This sets constraints for subsequent routing.
Route power and ground planes
Allocate dedicated internal layers for power and ground as required to simplify high-current routing and minimize interference for sensitive or high-speed signals.
Auto-route remaining nets
Use an auto-router to efficiently complete routing of less critical nets. Do a visual review of the auto-routed traces to simplify or clean up any messy or poorly routed traces.
Manually complete unrouted nets
Manually route any remaining or complex nets that the auto-router did not fully complete. If routing proves too difficult, consider adjusting placement or reconsider layer count and stack-up.
Perform final cleanup
Refine silkscreen text and placement, ensure clearances from copper and pads, and tidy other minor layout details.
Run a design rule check (DRC)
Verify that the layout adheres strictly to all design rules prior to prototype fabrication.
Complete an internal review checklist
Work through a standardized internal checklist to verify key design elements and proactively identify common issues before external review.
Obtain an independent review
Have an independent reviewer check the layout to catch potential errors or oversights missed during internal review.
Release for prototype manufacturing
Formally prepare and release the finalized files for prototype PCB fabrication, validating the design before proceeding to mass production.

Other Tips

Use a coarser grid when doing your final pass / clean up to help align things