Abstract: Disclosed is a method for the direct bonding of a copper sheet to a substrate made of an electrically insulating material, with the heating of the copper/substrate set in order to obtain a eutectic mixture. The method according to the invention consists in cleaning the copper to eliminate traces of oxidation on its surface before placing said copper on the substrate, in heating the copper/substrate set under a neutral atmosphere until a temperature greater than the temperature for the formation of the eutectic mixture is reached, and in applying the oxidating reactive gas only after the temperature greater than the temperature for the formation of the eutectic mixture is reached, in such a way that this temperature is reached before any oxidation of the surface of the copper.