When routing a PCB it is recommended to:

  • First place mounting holes allowing room for hardware - measure nuts, washers, etc.
  • Next, place footprints for components with fixed locations: connectors, switches, buttons, displays etc.
  • Use a standard snap grid (e.g. .050", .025" etc.)
  • Specify electrical nets, according to the schematic, using the logical connections, the edit nets dialog, or import netlists from a file.
  • Placed close to each other components with many connections between them.
  • Leave enough space between components to allow routing.
  • Place filtering capacitors as close to power supply pins as possible.
  • If a component footprint is not found in the library, create it by grouping objects or creating a custom footprint.
  • Avoid placing components at angles other than 0 and 90 degrees.
  • Consider factors which determine the proper trace width including operating current, operating temperature and board density.
  • Use wide trace-to-trace and pad-to-pad spacing for high impedance and high frequency, when "no-clean" fluxes or pastes are used and when board will be used in difficult climatic conditions.
  • Use a conformal coating (an insulating layer over the populated board) if the board will be exposed to humidity, moisture, dust etc.
  • Route power and other thicker traces first.
  • Route short traces before long ones.
  • For complex boards route traces horizontally on one side and vertically on the other side.
  • Avoid placing vias under fine-pitch components (especially BGA) as they might maintain flux even after cleaning which can cause problems.
  • Minimize the number of vias.
  • Avoid angles less than 90 degrees which can trap acid.
  • When placing text on copper layers, unmask the text so it is clearly visible.
  • Consider trace width for high current traces. I = 0.04 * (DeltaT ^ 0.44) * (A ^ 0.68) where:
    • I is the current in amps
    • DeltaT is the trace rise in temperature above ambient in degrees C
    • A is the trace cross sectional area in square mils (.001" ^ 2). One oz copper is 1.4 mil thick.