Abstract: A substrate strip includes a plurality of substrate units. A plurality of fingers is disposed in the substrate units. At least one of the corners of the fingers has a lead angle. A plurality of milling slots is formed on the peripheries of the substrate units and exposes out of the exposed sides of the fingers. The lead angles are adjacent to the exposed sides and can reduce the formation of burrs on the fingers during the formation of the milling slots. In another embodiment, a plurality of pads is provided if the fingers fail to be adjacent to the milling slots. Likewise, at least one of the corners of the pads also has a lead angle so as to reduce the formation of burrs on the pads during formation of the milling slots.