Multilayer wiring substrate, and method of producing same

摘要

A method of producing a multilayer wiring substrate is disclosed. The multilayer wiring substrate is free from a core substrate and includes a build up layer which includes an insulator layer and a wiring layer. One of a first main surface and a second main surface of the build up layer is formed with a metal supporting frame body. The method includes the steps of: forming a first insulator layer on a first main surface of a metal supporting plate, where the first insulator layer is included in the insulator layer and becomes a first resist layer which is positioned on the first main surface's side of the build up layer, and forming a first metal pad layer in a given position on a first main surface of the first insulator layer, where the first metal pad layer is included in the wiring layer and becomes a metal pad layer.