Method of manufacturing metal-base substrate and method of manufacturing circuit board

A method of manufacturing a metal-base substrate having an insulative adhesive layer and a conductor foil laminated in that order on a metal-based material, comprising:

• a dispersing step of dispersing a disperse phase in an insulative adhesive-dispersing medium that contains a wetting dispersant and constitutes the insulative adhesive layer, wherein the insulative-adhesive dispersing medium comprises an epoxy resin, a curing catalyst, and a solvent, wherein the solvent is present at 10 parts by weight or less, based on the total amount of the insulative-adhesive dispersing medium;
• a laminating step of laminating the insulative adhesive on the conductor foil as feeding the roll-shaped conductor foil;
• a first curing step of curing the insulative adhesive on the conductor foil under heat into a B stage state and thus forming a composite of the conductor foil and the insulative adhesive layer in the B stage state;
• a metal-based material-laminating step of laminating the metal-based material on the insulative adhesive layer in the B stage state to give a laminate;
• and
• a second curing step of curing the insulative adhesive layer in the B stage state into the C stage state by heat pressurization of the laminate under the condition of 70 to 260° C. and 0.1 to 10 MPa.