US Patent 7224583 Shielding box without any dedicated cooling duct

A shielding box includes a first wiring board and a second wiring board maintaining a distance relative to the first wiring board and facing thereto. A ventilating hole is formed in the second wiring board and having side surfaces facing each other. A pair of flat cables are extending through the insides of the side surfaces of the ventilating hole and are facing each other, the ends on one side thereof being connected to the first wiring board and the ends on the other side thereof being connected to the second wiring board. A cooling fan is disposed so as to blow the external air toward the first wiring board passing through the pair of flat cables.