Method for producing package substrate for mounting semiconductor device

A method for producing a package substrate for mounting a semiconductor device comprising an insulating layer and a wiring conductor provided on the insulating layer, wherein the method comprises:

• forming a first substrate with a single pressurizing by forming a laminate in which a first metal layer that has a thickness of 1 μm to 70 μm and that is peelable from a core resin layer, a first insulating resin layer, and a second metal layer in this order on both sides of the core resin layer having a thickness of 1 μm to 80 μm, then heating and pressurizing the laminate, wherein the heating is during the pressurizing, and no other pressing is performed before after the heating and pressurizing during the forming of the first substrate;
• forming a pattern on the second metal layer of the first substrate;
• forming a second substrate by heating and pressurizing a laminate formed by arranging a second insulating resin layer and a third metal layer in this order on a surface of the second metal layer of the first substrate;
• and
• peeling, from the core resin layer, a third substrate comprising, in order, the first metal layer, the first insulating resin layer, the second metal layer, the second insulating resin layer, and the third metal layer.