HEAT DISSIPATION SUBSTRATE FOR MOUNTING ELECTRIC COMPONENT

[Problem] An object of the present invention is to provide an electronic part mounting heat-dissipating substrate which enables a circuit for which a power semiconductor in which a large current flows is used to reduce the wiring resistances of a large power operation and improve the heat dissipation. [Means for Solving] The present invention is an electronic part mounting heat-dissipating substrate which comprises lead frames of wiring pattern shapes formed by conductor plate and an insulating member 130 which is provided between the lead frames 110, wherein a plate surface of a part arrangement surface of said conductor plate and a top surface of said insulating member at a side of said part arrangement surface form one continuous surface, the lead frames have different thicknesses, the thick lead frame 110H is used for a large current signal and the thin lead frame 110L is used for a small current signal, a plate surface of a back surface of the part arrangement surface and a top surface of the insulating member at a side of the back surface at the part arrangement surface-side are formed in an identical plane.