| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a wiring board with an excellent transmission characteristic of a high frequency signal in a through conductor. <P>SOLUTION: A wiring board 9a comprises: plural laminated insulation layers 1; a through conductor 3 penetrating through the plural insulation layers 1 in a thickness direction; and plural ground through conductors 4 penetrating through upper insulation layers 1b above lower insulation layers 1a including at least a lowermost insulation layer 1 among the plural insulation layers 1 in the thickness direction, and arranged to surround the through conductor 3 in a plane view. The wiring board 9a has an impedance at a lower end 3a at a portion of the through conductor 3 formed on the upper insulation layers 1b smaller than a portion above the bottom end 3a. The through conductor 3 has a portion 3a with a low impedance, and therefore, the impedance of the entire through conductor 3 becomes low, so as to improve a transmission characteristic of the through conductor 3 in a high frequency band. <P>COPYRIGHT: (C)2013,JPO&INPIT |
