PURPOSE: To improve the capacity of an allowable current by burying a refrigerant passing cooling conduit together with a conductor formed with a circuit in a resin board.

CONSTITUTION: A cooling conduit 13 made, for example, of a copper tube is buried near a buried conductor 11 formed with a predetermined circuit pattern. The end of the conduit 13 protrudes from a resin board 12, and when it is connected to a connector or other wiring component, a cooling conduit network is formed to the component. Fluid refrigerant is fed to the network to absorb Joule heat generated from the conductor 12 and to efficiently dissipate it externally. Thus, an increase in the conductor resistance due to temperature rise can be prevented to reduce the generation of Joule heat itself and the capacity of an allowable current can be improved as a circuit component.