SEMICONDUCTOR DEVICE

PURPOSE:To secure sufficient heat dissipation by contacting the part except the electrode pad of an LCC package through a good thermal conductive part with a substrate, thereby escaping the heat through a thermal conduction to the substrate. CONSTITUTION:A good thermal conductive part 9 made of a material such as gold is formed by electrically insulating from the pad 7 at the center where the pad 7 is not formed on the lower surface of the base 3 of an LCC package 2. A good thermal conductive part 13 is formed at the center of the region which is surrounded by the pad 12 on the surface of a substrate 11. When a semiconductor device 1 is operated, a pellet 5 generates heat, the package 2 is heated, and the heat is dissipated by convection and radiation from the outer surface of the base 3 and the cap 4 but insufficient. The heat is effectively transmitted to the substrate 11 by the thermal conduction through good conductive parts 9, 12, thereby obtaining sufficient heat dissipation.