PCB Design Rules

My Land Pattern Rules

• Through Hole Pins
  • Hole Size: Round lead size + 3 mil plating + 5 mil solder --> Round up see: Drill Bit Chart
  • Pad: Hole + 10-30 mil; provides 1/2 space from hole
  • Mask: Pad + 10 mil; provides 5 mil from pad
  • Clearance: 20 mil; provides 10 mil from pad

Design rules

Keep these in mind when making PCBs, especially through a "prototype" board house.

• Soldermask

Ben Jackson: "A crucial step I missed was to make a pass over all of the elements to set a unified copper clearance and soldermask aperture"
Experience w/ CustomPCB

• Mask must be "inside" the pads clearance when using flood fill, otherwise a small amount of fill will show out from under the mask. Plus you must cosider the board house alignment tolerance (e.g. +/- 3 mil). Make sure that your layout software is making the same shape mask clearance and flood clearance. Early versions of PCB had rounded corners for flood but square corners for mask.
• Mask less that 6 mil wide will not reliably stick to the board.

References

• PCB Design Guidelines - Has chart of PCB physical characteristics including voltage gaps