PURPOSE: To improve the effect of earth connection of the titled module with a package, and to inhibit the increase in heat resistance due to the change with time and the like by a method wherein projections are formed over the fixing surface of a heat-dissipating substrate, the tips of which projections are made to intrude to the opposited surface.

CONSTITUTION: The projections 9 saw-toothed in cross-section are formed in stripe form over the fixing surface 2A of the heat-dissipating substrate 2 loaded with the heat generator module 1. The grooves made by the projections 9 are coated with a jellied thermal conductive agent 8 having a good conductivity, and the substrate is placed on a package bottom plate 5 so that the fixing surface 2A may be opposite to the module mounting surface 5A, and is then fixed to the package 4 with a fixing screw 3. Thereby, the tip of the projection 9 intrudes to the mounting surface 5A, and the substrate 2, i.e., the heat generator module 1 is earth-connected to the package bottom plate 5, i.e. the package 4. Even when the thermal conductive agent 8 solidifies and exfoliates by change with time, the heat dissipating efficiency hardly varies because of the intrusion of the projections 9 to the package bottom plate 5.