Process for producing multilayer printed circuit board

A process for producing a multilayer printed circuit board, which comprises the steps of:

• a) drilling holes on positions of a film material selected from the group consisting of a film material obtained from a single sided copper-clad laminate having an insulating adhesive layer with a semi-cured state on an insulating surface and a film material obtained by forming an insulating adhesive layer with a semi-cured state on one side of a copper foil,
• b) laminating the hole-drilled film material on an innerlayer circuit substrate so as to contact the insulating adhesive layer with the innerlayer circuit substrate and pressing with heating to give an integral laminate,
• c) roughening surfaces of the insulating adhesive layer flowed into the holes at the time of lamination under pressure and heating,
• d) conducting electrical connection between a circuit on the inner layer circuit substrate and the copper cladding or foil of the film material by plating inner walls of the holes or by filling the holes with an electroconductive paste, and
• e) forming a circuit by processing the copper of the film material.