A structure to improve the cooling of electronic modules of the type including a printed circuit board contained between two covers. The structure extracts, by at least one of the covers, heat produced by at least one component borne by the printed circuit board. According to one feature, the cover responsible for extracting the heat bears at least one device having a high thermal conductivity, making it possible to even out the temperatures of the surface of the cover with which it is in contact. Such a structure may be particularly applied to the electronic modules on board aircraft.