| 摘要 |
<p>PURPOSE:To lessen an electromagnetic interference countermeasure component in mounting region on a printed board by a method wherein an LC filter is built in wiring layers in the printed board composed of, at least, four wiring layers. CONSTITUTION:A printed board 1 is composed of four wiring layers consisting of a surface wing layer 10, inner wiring layers 20 and 30 provided to a power supply surface and an ground supply surface respectively, and a wiring layer 40, and insulating layers 15, 25, and 35 of epoxy resin or the like. An LC filter 5 of pi type as an EMI countermeasure component composed of two capacitors 2 formed of ceramic dielectric in the layer 25 and an inductor 3 in the layer 15 is built in the printed in the printed board 1. By this constitution, an EMI countermeasure component can be lessened in mounting region, and a printed board can be enhanced in mounting density. The same result can be obtained even if an LC filter of T type is employed.</p> |
