A dissipator for electronic components, the electronic components being intended for the functioning of a rotary electrical machine, the machine comprising a rear bearing, the dissipator comprising a top face and a bottom face including fins. The present invention applies to any type of polyphase rotary electrical machine, synchronous or asynchronous, such as alternators or alternator starters, and also whether it is a case of electrical machines for motor vehicles and driven for example by belt, with cooling by air, liquid or any other solution that can be envisaged.