Lead frame for mounting a semiconductor chip and improving the packing density of devices such as a plastic chip carrier type IC is disclosed. A portion of inner leads, located parallel to the chip stage and the edge of a molded case is made as thin as possible and held by inner lead supporting bars to tie bars until the molding process is finished. After molding process is finished, these bars supporting the leads and stage are cut away. Packing density is improved an amount ranging from 20% to 30%.