MANUFACTURE OF LEAD FRAME

PROBLEM TO BE SOLVED: To prevent a bottom part of a square half-etch part from being oblique or rough by providing a linear resist pattern along a part corresponding to an edge part of a lead for etching. SOLUTION: As a pattern of an etching resist before etching, a linear resist pattern 14 is allocated at an edge part of a lead contacting to a side of a square half-etch part. Thus, an etching amount for a unit area and the flow of an etching liquid at the part is corrected, so that a bottom part of the square half-etch part is prevented from being oblique or rough. Then, the etching liquid is allowed to contact both front and rear surfaces of a metal thin plate for etching. As the result, related to the metal thin plate of the linear resist pattern 14 part, about half on an edge part side of the lead, of width b' of the linear resist pattern part, is melted and removed by side-etching from both surfaces, front and rear, which constitutes a part of a square half-etch part 3.