| 摘要 |
PROBLEM TO BE SOLVED: To reduce electromagnetic noise produced from a wiring board for mounting a commercial frequency switching circuit, such as a power controller, etc., and, at the same time to reduce the size of the wiring board. SOLUTION: To a wiring board 100 mounted with a power controller including electronic components 1-7, such as a power switching element, etc., a power supple input terminal 8, an output terminal 9 for load, a capacitance generating means 400 composed of an insulating layer 200 and a conductive layer 300 is provided close to the wiring surface of the board 100 on the opposite side. Since parasitic capacitances can be formed at all circuit nodes on the wiring surface, the high-frequency currents of the circuit nodes which becomes noise are by-passed through the parasitic capacitances and brings about negative feedback actions to the noise producing nodes. Therefore, noise currents flowing out of the terminals 8 and 9 can be substantially reduced.
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