印加点と同一基板面上にある伝送線路に伝播する基板接触放電ノィズの伝播挙動

摘要

基板に直接接触放電で印加した静電気ノイズが,印加点と同一基板面上にあるマイヶロストリップラインに伝播する挙動を,実験及び数値シミュレーションにて解析した.その結果,基板のグランド面を伝播する静電気ノイズの立ち上がりが高周波のため,その表皮効果により基板グランドの裏面には,直接伝播せず,基板端部を回り込んで伝達をする.そのため,印加点の裏面に配置した伝送線路へ伝播する静電気ノイズは,大きく減衰する.一方で,裏面に回りこんだ静電気ノイズは,基板グランドと対地グランド間で平行平板共振を発生するため,振動的になり,配線の位置関係なくほぼ一定となる.%The behavior of ESD noise was analyzed by experiments and numerical simulation. ESD was directly applied to the GND trace, which is assigned on the top layer of the PCB, and the induced fields propagated to a microstripline located on the same layer. Because the transient of the ESD is very rapid, the induced fields have high frequency components. The skin effect prevents the fields from getting to the opposite side of the GND layer directly, so the fields shall bypass the edge of the PCB. Thus the induced voltage on the trace on the opposite side is decried. On the other hand, the induced fields bypass the edge of the PCB and stay in the cavity between the PCB and the chassis, then cause a resonance. The noise induced on the trace which located on the opposite side is periodic and magnitude of the noise is uniform in the every point on the trace.