The assembly (22) involved in the fabrication of electronic cards comprises a plate (14) exhibiting a plurality of apertures (16) in which are respectively housed a plurality of electronic modules (2). These electronic modules are assembled to the plate 14 by fixing means, in particular by fixing bridges leaving a slot (26) over the major part of the surround of the electronic module. For example the fixing means are formed by projecting parts (18) at the periphery of the apertures (16), these projecting parts exhibiting a smaller thickness than the thickness of the plate (14) and serving as supports for the electronic modules, in particular for a substrate (12) of these modules. Fixing is performed for example by welding or adhesive bonding. The invention also relates to an intermediate product formed by such an assembly and a filing material that fills at least the major part of the remaining space in the apertures (16). The invention also relates to a method of fabricating cards in which the assembly according to the invention is finally coated in a resin to form substantially plane cards.