Mitsubishi Gas Chemical Company, Inc.

Hiroki Aoto

Morio Gaku

Yoshihiro Kato

Nobuyuki Ikeguchi

A method of making a high-density copper-clad multi-layered printed wiring board having a reliable through hole including providing a stacked assembly including three copper foil layers and at least two resin layers; providing an auxiliary material on a top surface of the stacked assembly and providing a backup sheet on a bottom surface of the stacked assembly to form an assembly; subjecting the top surface of the assembly to pulsed oscillation from a carbon dioxide laser to form at least one through-hole to produce a pulsed assembly; reducing the thickness of the front and reverse copper foil layers and simultaneously with reducing, removing copper foil burrs, to produce a cleaned assembly; and plating the cleaned assembly with copper to produce the high-density copper-clad multi-layered printed wiring board.

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Tokyo, Japan

Hiroki Aoto