| 摘要 |
PROBLEM TO BE SOLVED: To prevent leakage of electromagnetic wave to the outside in concentrated flow by providing a through hole connected to a ground layer coaxially to the outside of a signal through hole, and making radiation noise generated in signal current flow to a ground through hole by converting it to a return current. SOLUTION: A multilayer printed wiring board 1 has a four-layer structure with signal wirings 3, 4 arranged in front and rear surfaces of an insulation body 2 of resin, etc., and a ground layer 5 and a power supply layer 6 laminated in the insulation body 2. A signal through hole 7 is plated and made to pass through the insulation body 2 and connect the signal wirings 3, 4 and is formed tubular. Furthermore, a ground through hole 8 is plated to be connected to the ground layer 5 through the insulation body 2 outside the signal through hole 7 and is formed tubular. The ground through hole 8 has a clearance to the power supply layer 6 in the insulation body 2 and is not connected to the power supply layer 6. Electromagnetic wave generated in signal current flows concentrating to the through hole 8. |
