PURPOSE: To remove oxide films and contaminated substances and the like and improve the reliability of a semiconductor by purifying the surface of lead frames with deoxidizing and chemical polishing in the final process of die bonding or wire bonding when partially and wholly plated or uncovered semiconductor lead frames are manufactured.

CONSTITUTION: Lead frames are manufactured by plating an Fe-42 Ni Alloy or a Cu-2 Sn-0.2 Ni alloy with Cu and by stamping or etching after using only a Cu-0.1 Sn alloy. Subsequently, locations of die bonding or wire bonding ate dioxidized or polished chemically with mixed liquid of H2SO4, N2O2, and the like and further, oxides of metals as well as contaminants left on fine irregularities which are developed on the surfaces are removed wholly.