Abstract: Disclosed is a manufacturing method of a multilayer wiring board. The multilayer wiring board includes an outer resin insulation layer made of an insulating resin material, containing a filler of inorganic oxide and having an outer surface defining a chip mounting area to which an electronic chip is mounted with an underfill material filled in between the outer resin insulation layer and the electronic chip and holes through which conductor parts are exposed. The manufacturing method includes a hole forming step of forming the holes in the outer resin insulation layer by laser processing, a desmear treatment step of, after the hole forming step, removing smears from inside the holes of the outer resin insulation layer, and a filler reducing step of, after the desmear treatment step, reducing the amount of the filler exposed at the outer surface of the outer resin insulation layer.

Abstract: Disclosed is a manufacturing method of a multilayer wiring board. The multilayer wiring board includes an outer resin insulation layer made of an insulating resin material, containing a filler of inorganic filler and having an outer surface defining a chip mounting area to which an electronic chip is mounted with an underfill material filled in between the outer resin insulation layer and the electronic chip and holes through which conductor parts are exposed. The manufacturing method includes a hole forming step of forming the holes in the outer resin insulation layer by laser processing, a desmear treatment step of, after the hole forming step, removing smears from inside the holes of the outer resin insulation layer, and a filler reducing step of, after the desmear treatment step, reducing the amount of the filler exposed at the outer surface of the outer resin insulation layer.