Patent ID: 8028402

Claim:
A manufacturing method of a multi-layer wiring board, comprising steps (a) to (c): (a) preparing at least two connection boards by a method including the steps of (a1) to (a6), said connection boards having respectively an insulating resin composition layer, a connection conductor formed so as to pass through the insulating resin composition layer and a conductor circuit formed on the insulating resin composition layer and connected to the connection conductor; (a1) preparing a composite metallic layer having three layers, the composite metallic layer being formed of a first metallic layer including copper, a second metallic layer including copper, and a third metallic layer including nickel or its alloy which is disposed between the first metallic layer and the second metallic layer; (a2) selectively removing the first metallic layer and the third metallic layer from the composite metallic layer respectively to form the connection conductor on the second metallic layer; (a3) performing a roughening treatment for a surface of the connection conductor and the second metallic layer having the connection conductor thereon, and then covering the surface with the insulating resin composition layer, the insulating resin composition layer having at least one layer and being formed of an insulating resin composition; (a4) polishing a surface of the insulating resin composition layer to form a surface of the connection conductor exposed from the insulating resin composition layer; (a5) selectively removing the second metallic layer to form the conductor circuit; and then (a6) covering the surface of the connection conductor and the surface of the conductor circuit with a metal film respectively; (b) aligning the at least two of the connection boards obtained from the step (a) so as to provide aligned connection boards, and so as to join the connection conductors, or the connection conductor and the conductor circuit, via the metal film; and (c) laminating the aligned connection boards at a time by heating and pressing, so that the connection conductors, or the connection conductor and the conductor circuit are made into an alloy by solid phase metallic diffusion or melt bonding and conductively connected with each other, and the connection boards are mechanically connected with each other by the insulating resin composition layer.