Multilayer wiring board and method of making the same

A method of making a multilayer wiring board, comprising:

• forming a laminate plate composed of a first insulating layer, a second insulating layer comprising a softening temperature higher than the first insulating layer and a conductive layer arranged in this order,
• forming a core insulating layer that comprises an insulating material layer comprising a softening temperature higher than the first insulating layer and a conductive wiring formed on a surface of the insulating material layer,
• forming a composite substrate by contacting a surface of the laminate plate on a side of the first insulating layer with a surface of the core insulating layer, and bonding the laminate plate and the core insulating layer together while applying heat and pressure thereto,
• forming a through-hole for exposing the conductive wiring on the core insulating layer by penetrating the conductive layer through the first insulating layer of the composite substrate;
• and
• filling a conductive material in the through-hole for electrically connecting the conductive wiring and the conductive layer.