Blocking members are provided for limiting mold spread over a desirable area while a semiconductor is molded. The blocking members are composed within a metallic layer together with metallic leads by photoetching techniques. The blocking members are positioned at four corners of an aperture in a predetermined pattern of generally radial fingers extending cantilever-wise inwardly beyond the periphery of the aperture. The semiconductor is adapted to engage bumps on the semiconductor to the metallic leads by wire bonding methods. Extended portions of the metallic leads may also function as the blocking members, with the metallic leads being positioned at the four corners of the aperture.