Patent ID: 8393078

Claim:
A method of manufacturing a circuit board, comprising: a sticking step of sticking a protective film to a surface of a prepreg containing a fiber and a resin in a semi-curing state; a holing step of forming a hole on the prepreg through the protective film; an applying step of applying a conductive paste onto the protective film; a filling step of filling the hole with a part of the conductive paste; a peeling step of peeling the protective film to constitute, on the surface of the prepreg, a protruded portion formed of the conductive paste; a pressurizing step of providing a copper foil on both sides of the prepreg and carrying out pressurization by using a press device; a curing step of curing the prepreg and the conductive paste in a heating step subsequent to the pressurizing step; a patterning step of processing the copper foil into a wiring pattern; a first sticking step of sticking a first protective film to a surface of a first prepreg; a first holing step of forming a first hole on the first prepreg through a first protective film; a first applying step of applying the conductive paste onto the first protective film; a filling step of filling the first hole with a part of the conductive paste; a recovering step of collecting a plurality of conductive pastes which is not filled in the first hole and recovering the conductive pastes as a recovery paste; a filtering step of filtering the recovery paste to obtain a filtered recovery paste; an adjusting step of adding and mixing at least one of a solvent, a resin and a paste having a different composition from the filtered recovery paste into the filtered recovery paste to adjust at least a viscosity or a solid content, for obtaining a reuse paste; a second sticking step of sticking a second protective film to a surface of a second prepreg; a second holing step of forming a second hole on the second prepreg through the second protective film; a second applying step of applying the reuse paste onto the second protective film; and a filling step of filling the second hole with a part of the reuse paste, wherein the recovery paste in a paste state is filtered and a foreign substance containing a fiber piece taken away from the prepreg is removed to obtain the filtered recovery paste.