The invention relates to a substrate (2) for one or more light sources for a lighting and/or luminous signalling module for a motor vehicle, comprising a substrate (4) made of a heat-conducting material, preferably made of metallic material; at least one light source (12) such as a light-emitting diode, with a surface for mounting on the substrate (4), in thermal contact with the latter; and a circuit for controlling the power supply (10) of the one or more light sources (12). The circuit for controlling the power supply is electrically connected to the one or more light sources by means of metal wires welded on the surface (16) by the technology commonly referred to as "wire/ribbon bonding". The invention also relates to a method for assembling such a substrate.