PURPOSE: To enhance heat emission performance and facilitate component mounting by installing a component mount section which extends a metal sheet of a printed wiring board provided with said metal sheet in laminar shape, keeping the metal sheet exposed outwardly from a package section.

CONSTITUTION: A metal sheet 2, which constitutes a metal core type printed wiring board 1, comprises a package section 2a and a mount section 2b. The metal sheet 2 whose both sides are clamped by each insulation layer. A circuit pattern 4 is further formed outside the insulation layer 3 on the upper part. In the mount section 2b, the metal sheet is exposed as an extension of the package section 2a and folded at a right angle to the package section and set up as a front sheet. Radiation fins 6 and a connector 7 are installed to the mount section 2b. A display LED is also mountable. Heat emission problems and height limitation problems can be resolved by mounting the radiation fins 6 to the mount section 2b as the front sheet. Moreover, the package section 2a is also applicable to a net electronic component which constitutes a circuit, which enhances effective availability.