Wiring substrate

A wiring substrate, comprising:

• a core substrate including a through-hole conductor;
• a resin insulating layer formed on the core substrate;
• a conductor layer formed on a surface of the resin insulating layer and comprising a seed layer and an electrolytic plating layer formed on the seed layer;
• and
• a via conductor formed in the resin insulating layer such that the via conductor is connected to the through-hole conductor in the core substrate and includes the seed layer and electrolytic plating layer extending from the conductor layer,
• wherein the core substrate includes a glass substrate such that the through-hole conductor is formed in a through hole penetrating through the glass substrate, the resin insulating layer is formed on a surface of the glass substrate, and the core substrate has no conductor circuit formed on the surface of the glass substrate, and the conductor layer and via conductor are formed such that the seed layer is formed by sputtering and includes an alloy comprising copper, aluminum, and at least one metal selected from the group consisting of nickel, zinc, gallium, silicon, and magnesium.