OSH Park Docs
Diptrace: Ensuring plated holes
Our fabs use the presence of copper to determine whether or not a drill will be plated. Copper under a drill means via/plated hole, no copper means unplated hole.
Diptrace has an
Pad/Via Holes option which determines whether Diptrace will
remove the copper underneath drill hits. It’s very important that this box is
not checked, as it will remove the copper and thus prevent the fab prom
plating your vias.
Since this option renders a board unusable, you should take care to uncheck the Pad/Via Holes option before submitting your gerbers for manufacturing. By default, this box should be unchecked.