Manufacturing method of printed wiring board as well as copper-clad laminate and treatment solutions used therefor

摘要

There is provided a method for removing molten and scattered Cu and overhang that are generated around a via opening during laser machining in a direct laser via forming method of directly machining an outer-layer copper foil. In a manufacturing method of a printed wiring board of machining the via by laser directly through the copper foil of a copper-clad laminate in which the copper foil is clad on a base material resin, a process for machining the via is carried out in a sequence of (a) a copper foil surface treatment step of forming an oxide film on the surface of said copper foil, (b) a laser via machining step, (c) an alkali treatment step and (d) a molten and scattered Cu etching step. It is desirable to carry out (e) a de-smearing treatment after the molten and scattered Cu etching.