US Patent 7197820 Circuit board and its manufacturing method

A circuit board is provided in which peeling strength is prevented from decreasing and a connection resistance to a conductive material is prevented from increasing, though the contact area decreases when the circuit board has a copper foil. This circuit board has a metal film for covering a through hole on at least one surface of an insulating substrate having the through hole filled with the conductive material. An uneven layer with a thickness of 5 μm or more is formed on a surface of the metal film, and a metal layer is formed on the opposite surface to the uneven layer.