WIRING BOARD

摘要

PROBLEM TO BE SOLVED: To provide a wiring board which can stably activate a semiconductor element.SOLUTION: A wiring board A comprises: an insulation layer 3 having lower layer conductors 6 on an undersurface; a first mounting part 1a for mounting a first semiconductor element S1 having a first electrode pitch P1; a second mounting part 1b for mounting a second semiconductor element S2 which has a second electrode pitch P2 smaller than the first electrode pitch P1 and has a diagonal length smaller than a diagonal length of the first semiconductor element S1; first semiconductor element connection pads 11a of a pitch the same with the first electrode pitch P1; second semiconductor element connection pads 11b of a pitch the same with the second electrode pitch P2; first via holes 8a under the first semiconductor element connection pads 11a; second via holes 8b under the second semiconductor element connection pads 11b; first via conductors 10a in respective first via holes 8a; and second via conductors 10b in respective second via holes 8b. A diameter of the first via conductor 10a is larger than a diameter of the second via conductor 10b.