| 摘要 |
PROBLEM TO BE SOLVED: To suppress unnecessary radiating noise by shielding a power supply layer with a first ground layer and a second ground layer, and connecting the first and second ground layers via through holes. SOLUTION: A power supply layer 2 is sandwiched between a first ground layer 1a and a second ground layer 1b having a large area, adjacently positioned above and below the power supply layer 2 with a gap in-between, and the first ground layer 1a and the second ground layer 1b are electrically connected with each other via through holes 4 positioned outside the power supply layer 2, that is, positioned on the peripheral side so that the power supply layer 2 is encircled with the through holes. As a result, the power supply layer 2 is shielded at its upper, lower and peripheral portions, and thus unnecessary radiation from the power supply layer 2 is suppressed. Therefore, unnecessary radiation from the power supply layer 2 in the direction of the sides of the substrate is suppressed, and installation of members for unnecessary radiation control is not required, and accordingly the manufacturing cost can be reduced. |
