Ngk Spark Plug Company, Limited

Sotaro Tsukamoto

Masao Kuroda

Ryuji Imai

Susumu Wakamatsu

In a multi-layer wiring board having a strip line structure in which a grounding conductor wiring and a signal circuit wiring are disposed by interposing therebetween an insulation layer, the grounding conductor wiring is in the form of a grid and an open area ratio Rx [%]of the grid and a line width ratio Ry=Wg/Ws have a relationship expressed by Ry, .ltoreq.25.98.times.Rx.sup.-0.3871 -4.370 where Wg is the line width of the grounding conductor wiring, Sg is the width of an opening of the grid, Ws is the line width of the signal circuit wiring, and Rx={Sg/(Wg+Sg)}.sup.2 .times.100.

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Nagoya, Japan

Sotaro Tsukamoto