PURPOSE: To simplify a process and avoid copper residues in the etching process of a solder plating film by a method wherein residual photoresist is removed and simultaneously a protective film which is to be an etching resist film is formed on the solder plating film and, successively, the photoresist residues completely with a high speed.
CONSTITUTION: After photoresist 3a is removed, residual photoresist 3b remaining on a foundation copper layer 2 is ashed for a certain time with a plasma in 100% O2 gas. At that time, a Sn/Pb oxide film 6 is formed simultaneously on the surface of a solder plating film 5. After that, a plasma discharge is performed for a certain time in an atmosphere of O2 gas, CF4 gas and N2 gas with rations of, for instance, 70:20:10 to remove the residual photoresist 3b completely with a high speed. With this constitution, copper residues produced in an etching treatment process can be eliminated.
AKABOSHI HARUO
MIYAZAKI SATOYUKI
