Plastic layer for a smart card

Method of fabricating a plastic sheet involved in the formation of a plurality of smart cards which respectively include a plurality of electronic units, said plastic sheet being intended to at least partially receive the plurality of electronic units by penetration of this plurality of electronic units into the material forming said sheet, wherein the method includes the following steps:

• A) Taking a first sheet formed of a first material having a first hardness or a first Vicat softening temperature, said first sheet having a plurality of apertures and/or cavities;
• B) Respectively placing in said plurality of apertures and/or cavities a plurality of discs formed of a second material having a second hardness lower than the first hardness, respectively a second Vicat softening temperature lower than the first Vicat softening temperature, said plurality of discs having, in the geometric plane thereof parallel to the general plane of the first sheet, smaller dimensions than those of the corresponding apertures and/or cavities and a greater height, along an axis perpendicular to said general plane, to that of the corresponding apertures and/or cavities, so that the discs rise above a face of the first sheet;
• C) Exerting a pressure on each disc of the plurality of discs so as to reduce the respective heights thereof so that the discs are substantially flush with said face of the first sheet and at least partially in contact with the respective lateral walls of said plurality of apertures, respectively with the respective lateral walls and/or respective bottoms of said plurality of cavities;
• the plurality of discs thus being connected to the first sheet.