PCB layout decisions affect whether a design can be fabricated, assembled, inspected, and repaired. A layout that passes electrical design rules can still create manufacturing problems if DFM checks are left until the end.
Start with stackup and rules
The stackup should match the routing density, impedance needs, copper thickness, and board thickness. Design rules should be based on the manufacturer's capability instead of copied from a previous unrelated project.
For general design context, see PCB layout knowledge.
Via and routing decisions
Via type, trace spacing, return path, drill-to-copper clearance, and escape routing should be reviewed before the layout becomes crowded. Late via changes can affect impedance, layer count, and cost.
The page on PCB via types supports this part of the review.
Manufacturing and assembly checks
Copper balance, solder mask clearance, component spacing, fiducials, panel rails, and test access can influence yield and inspection. These details should be reviewed with the manufacturer before fabrication release.
For process context, review PCB circuit board production process.
What to send for review
Send Gerbers, drill files, stackup notes, impedance requirements, BOM, placement data if assembly is included, and drawings for any mechanical constraints. Clear input gives the manufacturer a better chance to find issues early.