The present invention prepares a member having a conductor-circuit-forming
copper foil formed on a protrusion-forming copper layer via an
etching-barrier layer formed of a different metal. Etching is selectively
performed for the protrusion-forming copper foil by using etchant that
does not etch the etching-barrier layer, and protrusions are thereby
formed. Then, the etching-barrier layer is removed using etchant that does
not etch the copper foil and using the protrusions as masks. An
interlayer-insulating layer is formed on a surface of the copper foil, on
which the protrusions are formed, so that the protrusions are connected to
the conductor circuit. Thereby, heights of the protrusions are uniformed,
and the reliability of connections can be improved.
