A circuit board (1) has a top face (2) for positioning an electronic component and a bottom face (4) used as a support on a heat-dissipating base. A plurality of heat transfer holes (12) provide heat transfer from the top face (2) to the bottom face (4). The heat transfer holes (12) are unevenly or non-uniformly distributed on the top face (2) in such a way that the top face (2) is provided with several free sectors (14) which are free of heat transfer holes (12) in order to connect the electronic component to the circuit board (1). The free sectors (14) are configured as columns or lines. A plurality of heat transfer holes (12) are placed at least along the long sides of the free sectors (14). The circuit board has a low thermal resistance between the electronic component and the heat-dissipating base.