It is observed that PCB designers are concentrating their attention on electronic parameters. Keeping eye on a large number of components available in the market, selecting the correct component and updating the component library they forgot to pay attention on production capacity of their supplier.
From our experience we can list out some basic guidelines here.
A mechanical layer should minimally contain:
Additional information that should be included in the mechanical plan when needed:
Minimum carbon line width: 0.30 mm
Minimum carbon – carbon spacing: 0.25 mm
Carbon pad should be 0.15 mm bigger than circuit pad.
Mask pad should be 0.15 mm bigger than circuit pads.
Means Mask pad = Carbon pad.