METHOD FOR FORMING RELIABLE VIA HOLE

摘要

PROBLEM TO BE SOLVED: To eliminate the need for desmearing treatment, by performing oxidation metal treatment onto the outer-layer copper foil of a copper-clad plate or by arranging the paint film or the like of an organic matter containing a specific capacity of specific metal compound powder, carbon powder, or the like, by applying a carbon dioxide gas laser beam with specific output, by eliminating the copper foil layer of a via hole, and by machining and eliminating one part of the outer layer of the copper foil being used as the bottom part of the via hole with the specific output. SOLUTION: In a method for forming a via hole, when a micro via hole for conducting electricity between first copper foil on the outer surface of a printed-wiring board and copper foil at a via part is made by a carbon dioxide gas laser beam, oxidation metal treatment is performed on the outer-surface copper foil of a copper-clad plate with at least two copper layers or the paint film or the like of an organic matter containing 3-97 vol.% metal compound powder with a melt point of 900 deg.C or more and at the same time a connection energy of 300 KJ/mol or larger and carbon powder is arranged, the carbon dioxide gas laser beam is applied with an output of 20-60 mJ/pulse, and the copper foil layer of the via hole is eliminated. After that, one part of the outer layer of the copper foil being used as the bottom pail of the via hole is machined and eliminated by the output of 20-35 mJ/pdlse, and the via hole is formed without passing through the copper foil.