Wiring substrate and method for manufacturing wiring substrate

A method for manufacturing a wiring substrate, comprising:

• preparing a laminate comprising a conductor layer and a resin insulating layer laminated on the conductor layer;
• forming a hole in the resin insulating layer such that the hole is connected to the conductor layer and is increased in diameter from a lower side at the conductor layer toward an upper side of the hole;
• forming a plating resist on the resin insulating layer such that the plating resist has a pad opening connected to the hole;
• filling the hole and the pad opening with a conductor such that a via conductor is formed in the hole and that a conductor pad is formed in the pad opening;
• forming a resist layer on the conductor pad such that the resist layer has a post opening connected to the conductor pad and that the post opening is increased in diameter from an upper side toward a lower side of the post opening at the conductor pad;
• and
• filling the post opening with a conductor such that a metal post is formed in the post opening.