CIRCUIT BOARD AND ELECTRONIC CONTROL UNIT

PROBLEM TO BE SOLVED: To make it difficult for an electromagnetic wave in a vehicle interior to resonate with noise emitted from an electronic control unit.SOLUTION: A circuit board 8 of an electronic control unit includes a plurality of layers A-F, a part of the layers being a plurality of ground layers B, E having different thicknesses from each other. When the thicknesses of the ground layers are different, the ground layers have different impedances from each other, thereby having different resonant frequencies from each other. By utilizing this, the resonant frequency of noise emitted from the electronic control unit is varied to make it difficult for an electromagnetic wave in a vehicle interior to resonate with the noise.SELECTED DRAWING: Figure 1 【課題】車室内の電磁波と、当該電子制御ユニットから放出されるノイズとが共振し難くする。【解決手段】電子制御ユニットの回路基板８は、複数の層Ａ〜Ｆを含むものであるが、複数の層のうちの一部が互いに厚みが異なる複数のグランド層Ｂ、Ｅとされる。グランド層の厚みが異なると、複数のグランド層の各々のインピーダンスが異なり、共振周波数が異なる。このことを利用し、当該電子制御ユニットから放出されるノイズの共振周波数を変えて、車室内の電磁波と共振し難くする。【選択図】図１