The present invention provides a structure and a method for prevention leakage of a substrate strip. The substrate strip includes an edge portion and a plurality of units. A patterned
metal layer on a surface of the substrate strip includes at least one plating
bus extended to the edge portion, a plurality of plating lines at the units, a plurality of contact pads at the units and a plurality of fiducial marks at the edge portion. The plating
bus has an extended trail having one end exposed out of the sidewall of the substrate strip. The fiducial marks and the contact pads are exposed out of a plurality of first openings of a
solder mask. The
solder mask also has a second opening at the edge portion exposing a portion of the plating
bus to define a breaking hole. After forming a
surface layer on the fiducial marks and the contact pads, the exposed portion of the plating bus is void of the
surface layer. By removing the exposed portion of the plating bus, the breaking hole is formed to electrically isolate the extended trail from the contact pads in order to prevent a
chip on the substrate strip from being damaged by ESD (
Electrostatic Discharge) during packaging processes.