Method of producing a multilayer wiring board

A method of producing a multilayer wiring board having a core substrate and wiring line patterns formed on both faces of the core substrate, the core substrate having conducting members piercing through the core substrate, and members of the wiring line patterns on both faces of the core substrate being connected with each other through the conducting members piercing through the core substrate, wherein the core substrate comprises via columns and conductive structural members, which are formed by plating, and an insulating structural member, which electrically insulates the individual via columns and conductive structural members from each other, the via column piercing through the core substrate and serving as the conducting member for connecting the members of the wiring line patterns on both faces of the core substrate with each other, the method comprising the steps:

• forming a patterned resist film on a surface of a conductor substrate,
• plating the surface of the conductor substrate provided with the patterned resist film using the resist film as a mask and the conductor substrate as an electrical power supply layer, to thereby form via columns and conductive structural members,
• removing the resist film,
• making a core substrate by forming a layer of insulating material on the surface of the conductor substrate so as to expose the top faces of the via columns and conductive structural members, the core substrate comprising the via columns, the conductive structural members, and an insulating structural member resulted from the layer of insulating material,
• forming, on the core substrate, a plurality of layers of wiring line patterns, each of which is separated from the underlying core substrate or layer of wiring line pattern by an insulating layer, and
• removing the conductor substrate.