Wiring board and method for manufacturing the same

A method for manufacturing a wiring board, comprising:

• forming a first penetrating hole in a substrate such that the first penetrating hole penetrates through the substrate between a first surface of the substrate and a second surface of the substrate on an opposite side of the first surface;
• forming a first through-hole conductor on an inner wall of the first penetrating hole of the substrate;
• filling a filler inside the first through-hole conductor;
• forming a second penetrating hole in the filler;
• forming a second through-hole conductor by filling a conductive material in the second penetrating hole;
• forming a first conductive circuit on the first surface of the substrate;
• forming a second conductive circuit on the second surface of the substrate such that the second conductive circuit is connected to the first conductive circuit by the first through-hole conductor;
• forming a first conductive portion on one end of the second penetrating hole;
• and
• forming a second conductive portion on an opposite end of the second penetrating hole such that the second conductive portion is connected to the first conductive portion by the second through-hole conductor.