Grids / Traces
- Use English measurements (mils, not mm)
- Place all components on .050 grid to start, .025 if required
- Trace width spacing minimum .006 / .006 (wider for power)
- Route on .025 grid to start, .0125 if required
- For metric / off-grid pads, route nearby then short off-angle segment to pad
ALWAYS WORK WITH GRID SNAP ON and set to a sensible value. "Sensible"
means normally .025 for placement, no smaller than .0125 for routing.
Use smaller only for special requirements or silkscreen text placement.
Holes / Pads
- Hole sizes specified are finished which are typically .003-.004 smaller than the drill size.
- A good minimum via size is .015 pad with .005 hole.
- For thru-hole component leads, specify a hole size at least .005 largerthan the lead diameter.
Silkscreen
- Minimum text height .040 and minimum line width .006
- Silkscreen text cannot overlap other silkscreen graphics, pads or holes
- Start with all text right-side up, rotate 90 degrees in one direction if needed
Selected PCB capabilities from mid-range houses as of June 2016
Feature | Advanced | Sunstone | Sierra
|
Outer Layer Trace Width (1 oz) | .005 | .006 | .003
|
Outer Layer Trace Spacing | .005 | .006 | .003
|
Innner Layer Trace width (1 oz) | .004 | |
|
Inner Layer Trace Spacing | .005 | |
|
Pad size over drill (dia) | .010 | | .006
|
Pad size over finish hole | | .018 |
|
Via size over drill (dia) | .008 | |
|
Minimum drill (full spec) | .006 | |
|
Minimum drill (quick proto) | | .010 |
|
Soldermask minimum web | .004 | .005 | .004
|
Soldermask clearance (std) | .002 | | .002
|
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