| 摘要 |
<p>PURPOSE:To reduce a crosstalk between signal wirings of a circuit board for placing a high speed IC chip and to satisfactorily match impedances of the wirings. CONSTITUTION:Through hole grooves 5 extended along GND wirings 3 are provided at a circuit board 1 in which signal wirings 2 and the wirings 3 are alternately formed on a main surface and a GND layer 4 is formed on a rear surface. The wirings 3 are electrically connected to the layer 4 through conductor layers 6 covering inner walls of the grooves 5.</p> |
