Process for producing a substrate

摘要

A substrate for a semiconductor device (14) comprises a resinous board (44) having a cavity (16) for mounting a semiconductor element (14), conductor patterns (40) formed on an upper surface of the resinous board (44), second conductor patterns (42) formed on an inner layer or a second, opposite surface of the resinous board (44) and a conductor section (26) formed on an inner wall of the cavity (16) for electrically connecting the first conductor patterns (40) to the second conductor patterns (42). First, a metallic layer (48) is formed on the inner wall of the cavity (16) of the resinous board (44). Then, a masking layer (52) is formed. The masking layer (52) is composed of a metal insoluble in an etching liquid for etching the metallic layer (48), so as to cover the metallic layer (48). The masking layer (52) is partially removed by a mechanical means so that the masking layer (52) remains at positions where the conductor section (26) are to be formed. The metallic layer (48) is etched by applying the etching liquid so that the metallic layer (48) is removed at positions not covered by the masking layer (52). The masking layer (52) is etched by applying another etching liquid, which can dissolve the metal of the masking layer (52), but cannot dissolve the metallic layer (48), so that the masking layer (52) is removed and thus the conductor section (26) is formed on the inner wall of the cavity (16).